Sikorsky S-67 Blackhawk airbrakes

Sikorsky S-67 Blackhawk Attack Helicopter

By William Pearce

In the late 1960s, Sikorsky Aircraft had many helicopter models in production, but they had lost contracts to develop new helicopters. In 1966, the United States Army’s Advanced Aerial Fire Support System (AAFSS) contract was awarded to Lockheed, but their AH-56 Cheyenne attack helicopter ran into serious design issues. On 20 November 1969, Sikorsky initiated development of a new helicopter to be used primarily as a gunship, but it could also be used in other roles. This helicopter was designated S-67 Blackhawk, and its design and construction was self-funded by Sikorsky.

Sikorsky S-67 Blackhawk airbrakes

The Sikorsky S-67 Blackhawk was a very versatile helicopter that exhibited great performance, but it also had various shortcomings that the US Army could not overlook. The helicopter’s narrow fuselage and air brakes are illustrated in this image.

The Sikorsky S-67 Blackhawk was designed as a high-speed attack helicopter with a small wing to generate lift. The pilot and copilot/gunner sat in tandem in the helicopter’s cockpit, with the copilot in the front seat and the pilot in the rear seat. The pilot accessed the cockpit from the left side of the helicopter and the copilot from the right. The narrow, streamlined fuselage was only 3 ft 10 in (1.2 m) wide, which decreased the helicopter’s drag and increased its survivability by presenting a smaller target to enemy gunners. Behind the cockpit was a compartment that could be used for additional equipment or to transport personnel.

Sikorsky S-67 Blackhawk tail

This image shows the S-67’s original tail that did not have any rudders. Note the tail’s camber. Air brakes can be seen on the upper wing surfaces. The main gear had a 7 ft (2.1 m) track.

To cut expense and development time, the S-67 was designed to use the dynamic drive power system from a Sikorsky S-61/SH-3 Sea King. This included two 1,500 hp (1,119 kW) General Electric T58-GE-5 turboshaft engines and their drive, rotor, hydraulic, and electrical systems. The S-67’s five-blade rotors had 22 in (559 mm) of their tips swept back 20 degrees to delay compressibility effects, lower vibration, and reduce noise. The net effect was that the blades allowed the helicopter to achieve higher speeds. The main rotors also had a hub fairing, and their collective pitch control was modified to increase sensitivity and range.

The S-67’s main gear retracted into sponsons mounted on the fuselage sides. The helicopter’s thin wings extended from the sponsons. Each wing featured two hardpoints for weapons, auxiliary fuel tanks, or equipment. Each wing also had three air brakes: two that deployed along its upper surface and one that deployed along the lower surface. With the air brakes deployed, the helicopter slowed twice as fast as without the air brakes. In addition, the air brakes could be deployed during combat to offer unrivaled maneuverability. The S-67 was the first helicopter with air brakes.

A five-blade, 10 ft 7 in (3.2 m) diameter tail rotor was mounted to the left side of the S-67’s vertical fin. A lower fin with a non-retractable tailwheel extended below the helicopter’s tail. The large upper and lower fins were cambered to counteract the torque of the main rotor at speeds above 46 mph (74 km/h). This enabled controlled flight without the tail rotor as long as the S-67’s forward speed was in excess of 46 mph (74 km/h). If the tail rotor was lost, the helicopter could be flown back to base and landed like a conventional aircraft. The S-67 used an all-moving horizontal stabilizer that increased the helicopter’s maneuverability and decreased rotor stress.

Sikorsky S-67 Blackhawk landing

Note the angle of the all-moving horizontal stabilizer as the S-67 comes in for a landing. The landing gear was found to be insufficient for operating from unimproved locations. The helicopter’s double main wheels sunk into soft ground, and the gear doors only had 9.75 in (248 mm) of clearance.

With a 7,000 lb (3,175 kg) payload, the S-67 could accommodate a variety of armaments. A removable Emerson Electric Company TAT-140 turret mounted under the cockpit could carry a 7.62 mm minigun (M134), a 20 mm three-barrel rotary cannon (M197), a 30 mm single-barrel cannon (XM140), a 30 mm three-barrel rotary cannon (XM188), or a 40 mm grenade launcher (M129). The four underwing hardpoints could carry two drop tanks, up to 16 TOW missiles, or up to eight rocket pods. Each 2.75 in (70 mm) rocket pod contained 19 rockets, for a total of 152 rockets.

Sikorsky S-67 Blackhawk side

The S-67’s rudders can be seen in this image. One is on the upper fin below the tail rotor, and the other is on the lower fin. Pylons have been installed on the wings’ hardpoints, with drop tanks mounted to the inner stations. The turret is installed with a M197 three-barrel 20 mm cannon.

The S-67 had a wingspan of 27 ft 4 in (8.3 m) and a rotor diameter of 62 ft (18.9 m). The fuselage was 64 ft 2 in (19.6 m) long, and the helicopter’s total length including the rotor was 74 ft 1 in (22.6 m). The S-67’s mast height was 15 ft (4.6 m), and the top of the tail rotor was 16 ft 4 in (5.0 m). The helicopter’s top speed was 213 mph (343 km/h); maximum cruise speed was 201 mph (324 km/h), and normal cruise speed was 167 mph (269 km/h). The S-67 could climb at 2,000 fpm (10.2 m/s) and had a service ceiling of 20,000 ft (6,096 m). The helicopter could hover in ground effect up to 9,700 ft (2,957 m) and could hover without ground effect up to 6,500 ft (1,981 m). Maximum range on internal fuel was 325 miles (523 km), but its normal combat range was 220 miles (354 km). With external fuel tanks, range was extended to over 600 miles (966 km). The S-67 had an empty weight of 12,525 lb (5,681 kg), a normal weight of 18,500 lb (8,391 kg), and a maximum takeoff weight of 22,050 lb (10,002 kg).

Sikorsky S-67 Colonge Germany 1972

The S-67 seen in the same configuration as the previous image. The helicopter is over Cologne, Germany on its European and Middle Eastern tour in 1972.

Construction on the S-67 started on 15 February 1970 and proceeded rapidly. The helicopter made its first flight on 20 August 1970. Flight testing proved the S-67 to be very responsive, maneuverable, smooth, and quiet. The helicopter was able to perform rolls, loops, and split-S turns—although, only rolls to the right were made. On 14 December 1970, Sikorsky test pilots Kurt Cannon and Byron Graham in the S-67 established a new absolute speed record by averaging 216.841 mph (348.971 km/h) over a 3 km (1.86 mile) course. They then set a new record on 19 December 1970 by averaging 220.888 mph (355.485 km/h) on a 15–25 km (9.3–15.5 mile) course.

In 1971, the S-67 covered 3,500 miles (5,633 km) touring 12 US military bases. In addition to Sikorsky demonstration flights, the helicopter was flown on 147 demo flights with military personnel. The S-67 completed 155 rolls and 140 split-S turns during these flights.

Sikorsky S-67 Blackhawk fan-in-tail

A fan-in-fin anti-torque system was tested in the S-67. Note the rudders above and below the fan. No issues were encountered with the fan-in-fin, but the helicopter was converted back to a conventional tail rotor.

Between 25 May and 13 June 1972, the S-67 was flown 26 hours for a series of flight evaluations by the US Army. The helicopter was competing against the Bell 309/AH-1 KingCobra to replace the AH-56 Cheyenne, which had been cancelled. For the AAFSS role, the S-67 was designated AH-3, and Sikorsky’s proposal included adding an additional hardpoint to each wing, bringing the total number to six. This would enable the S-67 to carry up to 24 TOW missiles. While the S-67 was praised for its performance and most of its flight characteristics, the evaluation recorded a number of shortcomings. The Army did not award either Sikorsky or Bell a contract and decided to initiate a new Armed Attack Helicopter program, which eventually was won by the Hughes AH-64 Apache.

The S-67 underwent a number of modifications in late 1972. Rudders were added to the ventral and dorsal fins to increase yaw control. The compartment behind the cockpit was altered to enable the transport of six troops. Hardpoints were added to the wingtips for each to carry a Sidewinder missile. A hoist was added under the helicopter that allowed the S-67 to transport a 7,000 lb (3,175 kg) external load.

Sikorsky S-67 Blackhawk cockpit

After the fan-in-tail rotor tests, a small door was added on the left side of the fuselage to access the compartment behind the cockpit. Initially, access was gained (with some difficulty) via the door under the fuselage (seen above). The S-67 was then painted a light desert camouflage, and this was the helicopter’s final configuration.

With no interest from the US Armed Forces, Sikorsky offered the S-67 for export. In late 1972, the S-67 was taken on a two-month tour of Europe and the Middle East. More than 7,500 miles (12,070 km) were covered, and the helicopter was flown for 136 hours. Despite interest from Israel, no orders were placed. Sikorsky then modified the S-67 to test a fan-in-fin tail rotor installation. A 4 ft 8 in (2.6 m), seven-blade rotor was installed in the modified tail. The helicopter underwent flight tests, including a dive at 230 mph (370 km/h). After the tests in 1974, the S-67’s tail was converted back to its previous configuration (with rudders), and a door to access the rear compartment was installed in the helicopter’s left side. The S-67 was then painted a light desert camouflage. The data from the fan-in-fin test was used for the Sikorsky H-76 fantail demonstrator, which tested the tail configuration later used in the Boeing-Sikorsky RAH-66 Comanche.

Sikorsky S-67 Blackhawk inverted

The S-67 made hundreds of rolls in its lifetime, but they were always to the right. The square in the fuselage above the wing is the window in the new rear compartment access door. What appear to be two rectangular windows can be seen father aft. Note the helicopter’s rudders and deployed air brakes.

On 26 August 1974, the S-67 arrived in the United Kingdom to start another European tour. On 1 September 1974, the S-67 was destroyed after failing to recover from a second roll during a practice session for the upcoming Farnborough Air Show. The copilot, Stu Craig, was killed in the crash, and the pilot, Kurt Cannon, died from his injuries nine days later. The accident was caused by the second roll being initiated in a less than ideal configuration combined with low altitude. However, the accident investigators believed that the crash was survivable had the helicopter been fitted with five-point harnesses rather than four-point harnesses. The S-67 had accumulated 598.7 hours at the time of the crash.

With the prototype destroyed and no interest from the US military, Sikorsky decided to end the S-67 Blackhawk program. Its swept-tip rotor blades were developed into those used on the Sikorsky S-70/UH-60 Black Hawk (the name similarity is a coincidence) and other helicopters. The S-67’s speed record stood for eight years until it was broken on 21 September 1978 by the Soviet Mil A-10 (modified Mi-24B) at 228.9 mph (368.4 km/h).

Sikorsky S-67 Blackhawk crash

The S-67 tries to recover from a roll a split second before it impacts the ground. The helicopter’s low altitude left no room to recover from the roll, which was rushed and initiated in a flawed manner. The crash would ultimately kill the pilot and copilot and end the S-67 program.

Sources:
http://www.sikorskyarchives.com/S-67%20BLACKHAWK.php
https://en.wikipedia.org/wiki/Sikorsky_S-67_Blackhawk
http://www.aviastar.org/helicopters_eng/sik_s-67.php
http://1000aircraftphotos.com/Contributions/Visschedijk/6269.htm
“Blackhawk’s Last Flight” Aeroplane Monthly (June 1976)
Attack Helicopter Evaluation, Blackhawk S-67 Helicopter by George M. Yamakawa, et al (July 1972)

Douglas XB-42 no1 in flight

Douglas XB-42 Mixmaster Attack Bomber

By William Pearce

In the early 1940s, Edward F. Burton began to investigate ways to simplify bomber aircraft. Burton was the Chief of Engineering at the Douglas Aircraft Company (Douglas), and he had noted that each subsequent generation of bomber aircraft was substantially larger, more complex, and more expensive than the preceding generation. Burton and his team started with a clean sheet of paper and designed what would become the XB-42.

Douglas XB-42 no1 in flight

The Douglas XB-42 Mixmaster had a unique design that provided very good performance. However, it was too late for World War II and too slow compared to jet aircraft. The first prototype (43-50224) is seen with its short tail on an early test flight.

Acting on their own, with no official United States Army Air Force (AAF) requirement, Burton and his team worked to design a two-engine tactical bomber with a top speed of over 400 mph (644 km/h) and that was capable of carrying 2,000 lb (907 kg) of bombs to a target 2,500 miles (4,023 km) away. The aircraft’s high speed would eliminate the need for extensive defensive armament, which would minimize the bomber’s crew and save weight. Burton’s team placed the wings, tail, and propellers in their optimal positions; the designers then filled in the rest of the aircraft with the needed equipment. What emerged from the drafting table was the Douglas Model 459: a mid-wing aircraft operated by a crew of three. At the rear of the aircraft were a set of coaxial contra-rotating pusher propellers driven by engines buried in the fuselage. In May 1943, Douglas proposed the aircraft to the AAF, and they were sufficiently impressed to order two prototypes and a static test airframe on 25 June 1943.

The AAF originally gave the aircraft the Attack designation XA-42. Douglas had presented the aircraft in a variety of roles that suited the Attack aircraft profile. However, the aircraft was reclassified as a bomber and redesignated XB-42 on 25 November 1943. Unofficially, the XB-42 was given the name Mixmaster, on account of its eight contra-rotating propeller blades loosely resembling a popular kitchen mixer.

The Douglas XB-42 Mixmaster was a very unique aircraft. It was an all-metal aircraft with a tricycle landing gear arrangement, which was novel at the time. A plexiglass nose covered the bombardier’s position. Atop the fuselage were two separate bubble canopies for the pilot and copilot. At the rear of the aircraft was a cruciform tail; its ventral fin contained an oleo-pneumatic bumper to protect the propellers from potential ground strikes during takeoff and landing.

Douglas XB-42 no1 nose

Nose view of the first prototype shows the twin bubble canopies to advantage. Both XB-42 aircraft were originally built with the canopies, but they were disliked. The second aircraft was later modified with a more conventional canopy.

The aircraft’s long wing used a laminar flow airfoil and was fitted with double-slotted flaps. An inlet in the wing’s leading edge led to the engine oil cooler and radiator, both fitted with electric fans for ground operation. After air flowed through the coolers, it was expelled out the top of the wing. The main landing gear retracted back into the sides of the fuselage, below and behind the wings. The complex retraction required the gear legs and wheels to rotate 180 degrees. Fuel tanks in each wing carried 330 gallons (1,249 L) of fuel. Four additional 275 gallon (1,041 L) fuel tanks could be installed in the bomb bay to extend the aircraft’s range. In addition, a 300 gallon (1,136 L) drop tank could be installed under each wing.

Housed in the fuselage behind the cockpit were two Allison V-1710 engines. Each engine was installed with its vertical axis tilted 20 degrees out from center, and the engines were angled toward the tail. Ducts flush with the aircraft’s skin and positioned below the cockpit on both sides of the aircraft brought induction air to the engines. A row of exhaust stacks was located above the leading edge of each wing, and two rows of exhaust stacks were positioned along the aircraft’s spine. The engines of the first XB-42 prototype produced 1,325 hp (988 kW) at takeoff and 1,820 hp (1,357 kW) at war emergency power. The second prototype had engines that produced 1,675 hp (1,249 kW) for takeoff and 1,900 hp (1,417 kW) for war emergency power.

Douglas XB-42 no2 gear retract

A unique view of the second prototype (43-50225) that displays the aircraft’s slotted flaps and uncommon main gear retraction that required the legs and wheels to rotate 180 degrees into the fuselage sides. Also visible are the wing guns and revised leading edge inlets, both features exclusive to the second prototype.

Extending from each engine was an extension shaft made up of six sections. The shaft sections were like those used in the Bell P-39 Airacobra (which used two sections). The shafts extended around 29 ft (8.8 m) and connected the engines to a remote, contra-rotating gear reduction box from an Allison V-3420-B engine. The gearbox had been slightly modified for the XB-42 and used a .361 gear ratio that was unique to the aircraft. Each engine turned a three-blade Curtiss Electric propeller. The left engine drove the forward propeller, which was 13 ft 2 in (4.01 m) in diameter. The right engine drove the rear propeller, which was 13 ft (3.96 m) in diameter. The engines and propellers were operated independently—if needed, one engine could be shut down and its propeller feathered while in flight.

To eliminate the danger the propellers presented to the crew during a bail out, a cord of explosives (cordite) was threaded through holes carefully drilled around the gearbox mount. Before bailing out, the crew could detonate the explosives, which would separate the gearbox and propellers from the aircraft.

Douglas XB-42 Allison engine test

Two Allison V-1710 engines connected to the V-3420 remote gear reduction for the contra-rotating propellers as used on the XB-42. The power system accumulated over 600 hours on the test stand and never caused serious issues during the XB-42 program.

The XB-42’s bomb bay was covered by two-piece, snap-action doors. The bay accommodated 8,000 lb (3,629 kg) of bombs, or a single 10,000 lb (4,536 kg) bomb could be carried if the doors were kept open six inches. The bay was long enough to carry two 13 ft 9 in (4.2 m) Mk 13 torpedoes. Two fixed .50-cal machine guns with 500 rpg were installed in the aircraft’s nose. Housed in the trailing edge of each wing, between the aileron and flap, were a pair of rearward-firing .50-cal machine guns, each with 350 rpg. The guns were concealed behind snap-action doors. Once exposed, the guns could be angled through a range of 30 degrees up, 15 degrees down, and 25 degrees to the left or right. Their minimum convergence was 75 ft behind the aircraft. The rear-firing guns were operated by the copilot, who rotated his seat 180 degrees to use the gun’s sighting system.

Douglas designers envisioned that the B-42 aircraft could be fitted with a solid nose containing different weapons for different roles. This is the same concept that was applied to the Douglas A-20 Havoc and A-26 Invader. Three of the possible B-42 nose configurations were as follows: eight .50-cal machine guns; two 37 mm cannons and two .50-cal machine guns; or a 75 mm cannon and two .50-cal machine guns. Douglas also thought the aircraft’s speed and range would make it very useful in a reconnaissance role. None of these plans made it off the drawing board.

The XB-42 had a 70 ft 6 in (21.49 m) wingspan and was 53 ft 8 in (16.4 m) long. Originally, the aircraft was 18 ft 10 in (5.7m) tall, but the tail and rudder were extended to cure some instability. The extension increased the XB-42’s height to 20 ft 7 in (6.3 m). A brochure published by Douglas in April 1944 predicted the B-42 would be able to carry 2,000 lb (907 kg) of bombs over 5,333 miles (8,583 km) and have a top speed of 470 mph (756 km/h). These numbers proved very optimistic. Perhaps the speed was a misprint, because some sources indicate the anticipated top speed was 440 mph (708 km/h). Regardless, the aircraft only achieved 410 mph (660 km/h) at 23,440 ft (7,145 m), and its cruising speed was 312 mph (502 km/h). The XB-42 had an empty weight of 20,888 lb (9,475 kg) and a maximum weight of 35,702 lb (16,194 kg). The aircraft’s service ceiling was 29,400 ft (8,961 m). Its combat range was 1,800 miles (2,897 km), but additional fuel tanks in the bomb bay could extend the XB-42’s range to a maximum of 5,400 miles (8,690 km).

Douglas XB-42 no2 rear

Rear view of the second prototype shows the ventral tail and rudder. Note the oleo-pneumatic bumper on the tail and its minimal ground clearance. The wing guns and new canopy are just barely visible.

Construction of the XB-42 proceeded rapidly. The AAF inspected and approved an aircraft mockup in September 1943, and the first prototype (43-50224) was completed in May 1944—one year after the aircraft was proposed and 10 months after the contract was awarded. The XB-42 flew for the first time on 6 May 1944, flown by Bob Brush and taking off from the Palm Springs Army Airfield in California. The second prototype (43-50225) flew for the first time on 1 August 1944, taking off from Santa Monica Airport in California.

Both XB-42s were originally fitted with separate bubble canopies. This cockpit layout was not very popular with the pilots. Although they could communicate via intercom, the pilots often found themselves leaning forward to speak with one another face to face under the canopies. The second aircraft was modified with a more conventional single canopy that encompassed both pilot and copilot. While the bubble canopies reduced drag, the single canopy was preferred. Another issue facing the aircraft was that cracks formed in the plexiglass nose. After the plexiglass was replaced several times, the nose was eventually covered with plywood.

Both prototypes were heavier than expected, which reduced performance. Some work went into lightening the second aircraft, like the use of hollow propeller blades. However, issues with vibrations occurred when disturbed air encountered the propellers, and this phenomenon was exacerbated by the hollow blades. No issues were encountered when the aircraft was clean, but when the bomb bay doors were open or when the gear or flaps were deployed, the vibration issue occurred. Some pilots lived with the vibrations and dismissed the issue, but other pilots found it very disconcerting. An improved propeller was designed that featured reversible blades to decrease landing roll and to slow the aircraft in flight. However, it was cancelled in March 1945 and was never built.

Douglas XB-42 no2 with canopy

Front view of the second prototype illustrates the aircraft’s revised canopy. The canopy on production aircraft would have been similar but more refined. Again, note the tail clearance and wing guns.

Some cooling issues were encountered, and modifications to the air intakes were made to improve airflow. The main gear was also modified a few times to improve its retraction and performance. Overall, the aircraft flew well, but the controls were not well harmonized. In addition, the XB-42 aircraft would encounter a slow dutch roll oscillation if not counteracted by the pilot. As previously mentioned, the tail of the aircraft was enlarged to resolve the issue, but it was never entirely solved. The XB-42 required a very long takeoff run of some 6,415 ft (1,955 m). Because there was only about 9 in (.23 m) of clearance between the ventral tail and the ground, the aircraft needed to build up a substantial amount of speed before it was carefully rotated for liftoff.

The second XB-42 prototype was the only aircraft to have revised wing inlets and to be fitted with its machine gun armament, although the guns were never tested. The second aircraft was flown around 70 hours before it was turned over to the AAF. On 8 December 1945, Lieutenant Colonel Henry E. Warden and Captain Glen W. Edwards flew the second XB-42 from Long Beach, California to Bolling Field in Washington, D.C. The record-setting, point-to-point flight covered 2,295 miles (3,693 km) in a time of 5:17:34—an average of 433.6 mph (697.8 km/h). The XB-42 had benefited from a favorable tailwind, and the aircraft’s average true airspeed was around 375 mph (604 km/h).

Douglas XB-42 wing guns

The guns in the left wing are seen aimed 30 degrees up and 25 degrees inboard. Only the second aircraft was fitted with the guns, and they were never tested. Note the snap-action doors that covered the guns. When open, the doors increased the XB-42’s directional stability, resulting in additional rudder force to give the desired yaw.

On 16 December 1945, the second XB-42 was lost during a test flight near Bolling Field. The aircraft was in a landing configuration when there was an issue with extending the landing gear. While the crew was troubleshooting the problem, the left engine began to overheat and then died. The right engine was taken to full power and began to overheat. The decision was made to bail out, and two of the crew safely jumped free before the pilot remembered to jettison the propellers. The propellers and their gearbox were successfully severed from the XB-42, and the pilot bailed out. All three crew members survived the ordeal without any injuries, but the aircraft was completely destroyed.

An exact cause of the crash was never determined, but it was speculated that the coolant doors were inadvertently left in their nearly-closed landing configuration while the crew investigated the gear issue. This resulted in the engines overheating. At the same time, a fuel tank switch was made a bit late and probably led to fuel starvation of the left engine. The second XB-42 had accumulated a little over 118 hours of flight time when it crashed.

The first XB-42 prototype had made 42 flights and accumulated over 34 flight hours by 30 September 1944. A year later, that number rose to around 150 flights, with the aircraft accumulating around 125 flight hours. Before the XB-42 had even flown, Douglas contemplated adding jet engines to the aircraft. An official proposal for the modification was submitted on 23 February 1945. The proposal was approved on 8 March 1946, and modifications to the aircraft began on 26 June 1946. At the time, the first XB-42 had made 168 flights and had flown around 144.5 hours. The two Westinghouse 19XB-2A (J30) jet engines were finally delivered in October 1946 and were installed on the aircraft.

Douglas XB-42A rear

Rear view of the XB-42A illustrates the notches in the new flaps to avoid the jet exhaust. The rest of the aircraft remained relatively unchanged from the XB-42 configuration. The cooling air exit can be seen on the right wing. Note the various Douglas aircraft in the background.

With the jet engines added to the first prototype, the aircraft was redesignated as the Douglas XB-42A. The 1,600 lbf (7.12 kN) thrust jet engines were mounted under the aircraft’s wings. New flaps were installed that were notched behind the jet engines. The notches allowed the flaps to avoid the jet exhaust when they were deployed. The fuel tanks in the wings were modified because of the jet engine mounts. Total wing tankage was decreased by 154 gallons (583 L), but two additional 74 gallon (280 L) tanks were installed in the fuselage. The jets themselves burned the same fuel as the piston engines. The aircraft’s instrumentation was also modified to accommodate the jet engines.

The XB-42A is listed as having a 70 ft 7 in (21.51 m) wingspan and a length of 53 ft 10 in (16.4 m). In reality, the wingspan was probably the same as the XB-42, and the length was slightly longer due to a different spinner. The aircraft’s height was 20 ft 7 in (6.3 m). The XB-42A had a predicted maximum speed of 488 mph (785 km/h) but only achieved 473 mph (761 km/h) at 14,000 ft (4,267 m); cruising speed was 442 mph (711 km/h). The XB-42A had an empty weight of 24,775 lb (11,238 kg) and a maximum weight of 44,900 lb (20,366 kg). The aircraft’s service ceiling was 34,500 ft (10,516 m). The XB-42A had a normal range of around 1,200 miles (1,931 km), but a maximum range of 4,750 miles (7,644 km) could be achieved with additional fuel tanks in the bomb bay.

Douglas XB-42A

The XB-42A makes a low pass over Muroc Air Base during an early test flight. Note the exhaust stains above the wing and the oil stains below the wing. The aircraft was outclassed by other jet aircraft, including its XB-43 cousin.

The first flight of the XB-42A (still 43-50224) occurred on 27 May 1947 at Muroc (now Edwards) Air Base in California. The aircraft required a lot of maintenance and did not prove remarkable in any category to justify further development. Despite the increased performance, the XB-42A was perched on the awkward dividing line between piston-powered aircraft of the past and jet-powered aircraft of the future. There is no better indicator of this than the fact that Douglas had already moved forward with an all-jet XB-42 aircraft, designated XB-43. The Douglas XB-43 Jetmaster had its jet engines buried in the fuselage, near were the Allison engines were installed on the XB-42. The first XB-43 was built using the XB-42 static test airframe. The jet-powered XB-43 made its first flight on 17 May 1946—little more than a year before the jet/piston-powered XB-42A first flew. The XB-42A made only 23 flights, accounting for a little under 18.5 hours of flight time.

With technological progress outpacing the XB-42A, the aircraft was donated to the Air Force Museum on 30 June 1949. It was later moved to the National Air and Space Museum’s Paul Gerber Facility in Silver Hill, Maryland, where it was stored for a number of years. In 2010, the XB-42A was transferred to the National Museum of the United States Air Force in Dayton, Ohio. The aircraft, along with second XB-43 prototype, will eventually be restored for static display.

Douglas persisted with the pusher configuration and designed a number of other military and commercial aircraft. The most developed design was that of the Model 1004, which was actually designated DC-8. Known as the Skybus, the aircraft was similar to an XB-42, but with an extended fuselage for airline service. The aircraft could seat a maximum of 48 passengers, and the extension shafts from the Allison engines travelled under the passenger compartment. First proposed in October 1945, the Skybus was never built, and the DC-8 designation was reapplied to Douglas’s first jet airliner.

Douglas DC-8 Skybus

Although visually similar to the XB-42, the Douglas DC-8 Skybus was an entirely new design. The aircraft’s excellent performance and great single-engine handling was not enough to justify its expense over more conventional designs.

Sources:
American Bomber Development in World War 2 by Bill Norton (2012)
Vee’s for Victory! The Story of the Allison V-1710 Aircraft Engine 1929-1948 by Daniel D. Whitney (1998)
McDonnell Douglas Aircraft since 1920: Volume I by René J Francillon (1979/1988)
The Allison Engine Catalog 1915–2007 by John M. Leonard (2008)
“The First, The Last, and the Only” by Walt Boyne, Airpower Vol. 3 No. 5 (September 1973)
“The Douglas DC-8 Skybus” by R. E. Williams, Douglas Service Vol. 41 (second quarter 1984)
http://www.enginehistory.org/Propellers/Curtiss/XB-42Prop.shtml

Dutheil Chalmers Eole props rear

Dutheil-Chalmers Éole Opposed-Piston Aircraft Engine

By William Pearce

In 1906, the French company Société L. Dutheil, R. Chalmers et Cie (Dutheil-Chalmers) began developing aircraft engines for early aviation pioneers. The company was headquartered in Seine, France and was founded by Louis Dutheil and Robert-Arthur Chalmers. Although most of their engines were water cooled, the Dutheil-Chalmers’ horizontal aviation engines may have been the first successful versions of the horizontal type that is now used ubiquitously in light aircraft. Continuing to innovate for the new field of aviation, Dutheil-Chalmers soon developed a line of horizontal, opposed-piston engines.

Dutheil Chalmers Eole patent

Taken from the Dutheil-Chalmers British patent of 1909, this drawing shows the layout of the horizontal, opposed-piston engine. The dashed lines represent the bevel-gear cross shaft that synchronized the two crankshafts.

On 23 November 1908, Dutheil-Chalmers applied for a French patent (number not found) that outlined their concept of an opposed-piston engine. The French patent is referenced in British patent 26,549, which was applied for on 16 November 1909 and granted on 21 July 1910. In the British patent, Dutheil-Chalmers stated that the engine would have two crankshafts. The output shaft would not be a power shaft that connected the two crankshafts. Rather, the crankshafts would rotate in opposite directions (counter-rotating), and a propeller would mount directly to each crankshaft. This is the same power transfer method used in the SPA-Faccioli opposed-piston aircraft engines. While the Dutheil-Chalmers and SPA-Faccioli engines shared a similar concept and were built and developed at the same time, there is no indication that either company copied the other.

The Dutheil-Chalmers opposed-piston engines are sometimes referred to as Éole engines. It is not clear if Dutheil-Chalmers marketed the engines for a time under a different name or if Éole was just the name they gave to their line of opposed-piston engines. Éole is the French name for Aeolus, the ruler of the winds in Greek mythology. The engines were primarily intended to power airships. The two counter-rotating propellers would cancel out the torque associated with a single propeller on a standard engine. In addition, the opposed-piston engine’s two-propeller design did not require the heavy and cumbersome shafting and gears necessary for a conventional single-crankshaft engine to power two propellers.

Dutheil Chalmers Eole 2 view

Top and side view drawings of the four-cylinder, opposed-piston engine. The drawings show no valve train and differ slightly from photos of the actual engine, but they give an idea of the engine’s general layout.

Four different horizontal, opposed-piston engine sizes were announced, all of which were water-cooled. Three of the engines had the same bore and stroke but differed in the number of cylinders used. These engines had two, three, and four cylinders. Each had a 4.33 in (110 mm) bore and a 5.91 in (150 mm) stroke, which was an 11.81 in (300 mm) stroke equivalent with the two pistons per cylinder. The two-cylinder engine displaced 348 cu in (5.7 L) and produced 38 hp (28 kW) at 1,000 rpm. The engine weighed 220 lb (100 kg). The three-cylinder engine displaced 522 cu in (8.6 L) and produced 56 hp (42 kW) at 1,000 rpm. The engine weighed 397 lb (180 kg). The four-cylinder engine displaced 696 cu in (11.4 L) and produced 75 hp (56 kW) at 1,000 rpm. The engine weighed 529 lb (240 kg). It is not clear if any of these engines were built.

The fourth engine was built, and it was the largest opposed-piston engine in the Dutheil-Chalmers line. The bore was enlarged to 4.92 in (125 mm), and the stroke remained the same at 5.91 in (150 mm)—an 11.81 in (300 mm) equivalent with the two pistons per cylinder. The four-cylinder engine displaced 899 cu in (14.7 L) and produced 97 hp (72 kW) at 1,000 rpm. Often, the engine is listed as producing 100 hp (75 kW). The four-cylinder engine weighed 794 lb (360 kg).

Dutheil Chalmers Eole front

This Drawing illustrates the front of the Dutheil-Chalmers opposed-piston engine. Note the cross shaft that synchronized the two crankshafts. The gear on the cross shaft drove the engine’s camshaft. The pushrods, rockers, and valves are visible.

Only the 97 hp (72 kW) engine was exhibited, but it was not seen until 1910. The engine was displayed at the Paris Flight Salon, which occurred in October 1910. The engine consisted of four individual cylinders made from cast iron. The horizontal cylinders were attached to crankcases on the left and right. Threaded rods secured the crankcases together and squeezed the cylinders between the crankcases. Each crankcase housed a crankshaft, and the two crankshafts were synchronized by a bevel-gear cross shaft positioned at the front of the engine. A two-blade propeller was attached to each crankshaft. The propellers were phased so that when one was in the horizontal position, the other was in the vertical position.

Near the center of the cross shaft was a gear that drove the camshaft, which was positioned under the engine. The camshaft actuated pushrods for the intake valves on the lower side of the engine and the exhaust valves on the upper side of the engine. The pushrods of the intake valves travel between the cylinders. All of the pushrods acted on rocker arms that actuated the valves positioned in the middle of the cylinder. Each cylinder had one intake and one exhaust valve.

No information has been found that indicates any Dutheil-Chalmers Éole opposed-piston engines were used in any airship or aircraft. Still, it is a unique engine conceived and built at a time of great innovation, not just in aviation, but in all technical fields.

Dutheil Chalmers Eole props rear

The 97 hp (72 kW), four-cylinder, eight-piston engine on display at the Paris Flight Salon in 1910. The engine has appeared in various publications as both a Dutheil-Chalmers and an Éole. Note the rods that secured the crankcases together. What appears to be the camshaft can be seen under the engine.

Sources:
Les Moteurs a Pistons Aeronautiques Francais Tome II by Alfred Bodemer and Robert Laugier (1987)
“Improvements in or connected with Motors especially applicable to Aviation and Aerostation Purposes” GB patent 26,549 by L. Dutheil, R. Chalmers and Company (granted 21 July 1910)
“Motors for Aerial Navigation—V” by J. S. Critchley, The Horseless Age (26 October 1910)
“Aerial Motors at the Salon” by Oiseau, Flight (5 November 1910)

SPA-Faccioli N3 rear

SPA-Faccioli Opposed-Piston Aircraft Engines

By William Pearce

Aristide Faccioli was an Italian engineer. In the late 1800s, he became fascinated with aviation and worked to unravel the mysteries of powered flight. With little progress in aviation, Aristide had turned to automobile development by 1898. He worked for Ceirano GB & C and designed Italy’s first automobile, the Welleyes. Ceirano GB & C did not have the finances to produce the automobile, so a new company was established for automobile production. This company was called Fabbrica Italiana Automobili Torino or FIAT, and it bought the rights, plans, and patents for the Welleyes. The Welleyes became FIAT’s first production automobile, the 3 ½ CV.

SPA-Faccioli N1

The SPA-Faccioli N.1 engine with its four cylinders, each housing two opposed pistons. At the rear of the engine (bottom of image) is the cross shaft linking the two crankshafts. Note the gear on the cross shaft that drove the camshaft.

Aristide became FIAT’s first technical director, but he left in 1901 to start his own automobile company. In 1905, Aristide moved from automobile production to engine design. However, Aristide’s focus returned to aviation once he learned of the successful flights of the Wright Brothers and other early pioneers. In 1907, Aristide shut down his companies and worked on aircraft and aircraft engine designs. In 1908, Aristide visited a close friend, Matteo Ceirano, seeking financial support. Matteo was one of Ceirano GB & C’s founders and was a co-founder of SPA (Società Ligure Piemontese Automobili). Matteo and SPA backed Aristide and encouraged him to continue his aeronautical work.

Aristide’s first engine was the SPA-Faccioli N.1. The N.1 was a water-cooled, horizontal, opposed-piston engine. Each side of the engine had a crankshaft that drove pistons in the engine’s four, individual cylinders. Attached to each crankshaft was a propeller. The crankshafts and their propellers turned in opposite directions (counter-rotating). When viewed from the rear of the engine, the right propeller turned clockwise, and the left propeller turned counterclockwise. The two-blade, wooden propellers were phased so that when one was horizontal the other was vertical. The dual, counter-rotating propeller design was an effort to eliminate engine vibrations and cancel out propeller torque.

SPA-Faccioli N2

This rear view of the SPA-Faccioli N.2 illustrates that the engine was much more refined than the N.1. Note the magneto driven above the cross shaft and the gear train driven below.

The two crankshafts were synchronized by a bevel-gear cross shaft that ran along the rear of the engine. Geared to the cross shaft was a camshaft that ran under the engine. The camshaft actuated the intake and exhaust valves that were located in the middle of each cylinder. As the two pistons in each cylinder came together, the air/fuel mixture was compressed. Once the mixture was ignited by the spark plug in the middle of the cylinder, the expanding gasses pushed the pistons back, operating like any other four-stroke engine. The N.1 had a 4.41 in (112 mm) bore and a 5.91 in (150 mm) stroke. The two pistons per cylinder effectively gave the N.1 an 11.81 in (300 mm) stroke. The engine displaced 721 cu in (11.82 L) and produced 80 hp (60 kW) at 1,200 rpm. The N.1 weighed 529 lb (240 kg).

The N.1 engine was installed in the Faccioli N.1 aircraft, which was a triplane pusher design. Flown by Mario Faccioli, Aristide’s son, the engine, aircraft, and pilot all made their first flight on 13 January 1909. The aircraft quickly got away from Mario, and the subsequent crash injured Mario and destroyed the aircraft. Although brief, the flight marked the first time an Italian-designed and built aircraft was flown with an Italian-designed and built engine. With all parties undeterred, the N.1 engine was installed in the Faccioli N.2 aircraft (a biplane pusher with a front-mounted elevator) and flown by Mario in June 1909. After a few flights, Mario and the N.2 aircraft were involved in an accident that again injured Mario and destroyed the aircraft.

Faccioli N3 aircraft

Mario Faccioli sits on the Faccioli N.3 aircraft in 1910. Note the covers over the N.2 engine’s cross shaft bevel gears. Since the propellers rotated in opposite directions, when one was vertical, the other was horizontal.

After these setbacks, Aristide designed a new engine, the SPA-Faccioli N.2. The N.2 had many features in common with the N.1: water-cooling, opposed-pistons, dual crankshafts, a bevel-gear cross shaft, and counter-rotating propellers. However, the N.2 was a single cylinder engine. The engine’s magneto was driven from the cross shaft. The N.2’s intake was positioned on the bottom side of the engine, and exhaust was expelled from the top side. The N.2 had a 3.94 in (100 mm) bore and a 5.12 in (130 mm) stroke—a 10.24 in (260 mm) equivalent for the two pistons per cylinder. The engine displaced 249 cu in (4.08 L) and produced 20 hp (15 kW) at 1,200 rpm and 25 hp (19 kW) at 1,500 rpm. The N.2 weighed 106 lb (48 kg).

The N.2 engine was installed in the Faccioli N.3 aircraft. With a very similar layout to the N.2 aircraft, the N.3 pusher biplane was smaller and did not have the front-mounted elevator. Mario was again the test pilot, and he first flew the aircraft on 12 February 1910. Many flights were made throughout February and March. On 26 March 1910, one propeller came off the engine and damaged the aircraft while it was in flight. Mario was injured in the subsequent crash, and the N.3 aircraft was damaged. Aircraft and pilot flew again in the summer, but Aristide was already working on a new aircraft design.

SPA-Faccioli N3 rear

This rear view of the SPA-Faccioli N.3 shows many features common with the N.2 engine. However, note the 20 degree cylinder angle extending from the crankshafts. The camshaft was driven from the cross shaft and extended through the engine. Two pushrods extend from both the top and bottom of the camshaft. The black plugs in the center of the cylinders cover ports for spark plugs. (W. R. Pearce image)

The N.2 engine was installed in the Faccioli N.4 aircraft, a further refinement of the Faccioli line. The aircraft was first flown by Mario in July 1910. On 15 October 1910, Mario used the N.4 aircraft to get his Italian pilot’s license (No. 21). This was the first time an Italian-designed and built aircraft was used to obtain a pilot’s license.

For his next aircraft, the Faccioli N.5, Aristide needed more power. The new SPA-Faccioli N.3 engine was built upon knowledge gained from the previous engines. Again, the engine was water-cooled with opposed-pistons and had dual crankshafts (synched by a bevel-gear cross shaft) that drove counter-rotating propellers. However, the cylinder arrangement of the N.3 was unique. In essence, the N.3 was made up of two V-4 engines mounted horizontally and attached together via their combustion chambers. The cylinders of the complete engine formed a diamond shape, with the cylinders angled at 20 degrees relative to the crankshaft. This gave the cylinders a 160 degree bend at their middle. Technically, the pistons no longer shared a common cylinder, but the cylinders did still share a combustion chamber. Some sources define the N.3 as a four-cylinder opposed-piston engine, and other sources define it as an eight-cylinder engine in which opposed pairs of cylinders shared a common combustion chamber.

SPA-Faccioli N3 front

The N.3 engine’s intake manifold can be seen on the left side of the image; the exhaust ports are also visible to the right of the valves. Note the camshaft extending through the engine, and the pushrods that actuated the valves. The front side of the engine still has its two spark plugs.

Two magnetos were driven from the cross shaft at the rear of the N.3 engine. The magnetos fired one spark plug per cylinder pair. The spark plugs were positioned either on the front of the engine or on the back, depending on the cylinder. The cross shaft also drove a short camshaft that extended through the diamond between the cylinders. Via pushrods and rocker arms, the camshaft actuated the one intake and one exhaust valve for each cylinder pair. An intake manifold mounted to the front of the engine brought air and fuel into the right side of the engine, and the exhaust was expelled from the left side of the engine. The N.3 had a 2.95 in (75 mm) bore and a 5.91 in (150 mm) stroke. The engine displaced 324 cu in (5.30 L) and produced 40 hp (30 kW) at 1,200 rpm and 50 hp (37 kW) at 1,600 rpm. The N.3 weighed 198 lb (90 kg).

The N.3 engine was finished in early 1911, but the Faccioli N.5 aircraft was not. The N.3 engine was installed in the N.4 aircraft, and Mario continued his role as chief pilot. The N.3-powered N.4 aircraft was entered in various competitions during the Settimana Aerea Torinese (Turinese Air Week) held in June 1911. On 25 June 1911, the last day of the competition, a mechanical failure on the aircraft caused Mario and the N.4 to crash. As with previous crashes, Mario was injured, and the aircraft was destroyed.

Faccioli N4 aircraft

The Faccioli N.4 aircraft was originally powered by the SPA-Faccioli N.2 engine. In 1911, the eight-cylinder SPA-Faccioli N.3 engine was installed. This image was taken in June 1911, with the N.3 engine installed and Mario in the aircraft.

It is not clear if the Faccioli N.5 aircraft was ever completed. Aristide’s involvement in aviation seemed to wane after the crash of the N.4 aircraft. In fact, the last SPA-Faccioli engine may have been a development of the N.3 undertaken exclusively by SPA without much involvement from Faccioli.

Built in late 1911 or early 1912, the SPA-Faccioli N.4 engine was an enlarged and refined N.3. With the N.4, eight cylinders were again positioned in a diamond configuration, angled at 20 degrees at the crankshafts and 160 degrees at the combustion chambers. Each opposed cylinder pair shared a common combustion chamber. Each cylinder pair now had two spark plugs, and they were fired by two magnetos, one driven directly from the rear of each crankshaft. The cross shaft synchronizing the crankshafts also served as the camshaft. At the rear of the engine, the cross shaft drove pushrods that acted on rocker arms mounted to the top and bottom of the engine. The rocker arms actuated the one intake and one exhaust valve per cylinder pair, positioned at the center of the cylinders. The intake manifold was positioned behind the engine, to the left of center. The manifold fed the air/fuel mixture to a passageway in the cylinder casting that ran on the left side of the valves. The exhaust was expelled to the right of the valves.

SPA-Faccioli N4 front

The SPA-Faccioli N.4 was the final refinement of the Faccioli engine line. The magnetos can be seen behind the engine; each was driven from the rear of a crankshaft. Note the two spark plugs per cylinder pair. (W. R. Pearce image)

The N.4 engine had a 3.74 in (95 mm) bore and a 5.91 (150 mm) stroke. The engine displaced 519 cu in (8.51 L) and produced 80 hp (60 kW) at 1,200 rpm and 90 hp (67 kW) at 1,600 rpm. The N.4 was 54 in (1.38 m) wide, 32 in (.82 m) long, 22 in (.57 m) tall, and weighed 441 lb (200 kg). No information has been found to indicate that the engine was installed in any aircraft.

After surviving so many close calls, Mario Faccioli was sadly killed in a plane crash in March 1915. The type of aircraft involved in the crash is not known. Aristide Faccioli never achieved the success he strived for and never recovered from his son’s death. He took his own life on 28 January 1920.

SPA-Faccioli N.3 and N.4 engines are preserved and on display in the Museo Storico dell’Aeronautica Militare in Vigna di Valle, Italy. An N.4 engine is displayed in the Museum of Applied Arts & Sciences, Museums Discovery Centre in Castle Hill, Australia. The museum lists the engine as a “300 hp, model 2-A,” undoubtedly confusing the eight-cylinder SPA-Faccioli engine with a SPA Type 2-A straight-eight engine. Also, the N.4 is positioned upside-down in its display stand.

SPA-Faccioli N4 rear

This rear view of the N.4 engine shows how the cross shaft also acted as the camshaft and directly drove the pushrods. The valves in the foreground are for the intake. The port for the intake manifold can just be seen at the center of the engine. Note the mounts for the magnetos and that the engine is upside-down in its display stand. (Museum of Applied Arts & Sciences image)

Sources:
Origin of Aviation in Italy by Piero Vergnano (1964)
Aeronuatica Militare Museo Storico Catalogo Motori by Oscar Marchi (1980)
Jane’s All the World’s Aircraft 1912 by Fred T. Jane (1912/1968)
http://collection.maas.museum/object/206770
http://www.treccani.it/enciclopedia/aristide-faccioli_(Dizionario-Biografico)/
http://it.wikipedia.org/wiki/Aristide_Faccioli

Martin-Baker MB5 dH front

Martin-Baker MB5 Fighter

By William Pearce

On 12 September 1942, the Martin-Baker MB3 fighter crashed after its Napier Sabre engine seized. Company co-founder Captain Valentine H. Baker was killed during the attempted forced landing. James Martin, the aircraft’s designer, had already designed the MB3A, which was the production version of the MB3 that incorporated several changes to enhance the fighter’s performance. The second MB3 prototype was to be completed as a MB3A. After the MB3 was destroyed and Baker was killed, Martin wanted to further alter the aircraft’s design to improve its safety and performance. Perhaps the paramount change was to replace the Sabre engine with a Rolls-Royce Griffon.

Martin-Baker MB5 Rotol front

The Martin-Baker MB5 was one a few aircraft that sat at the pinnacle of piston-engine fighter development. Here, the aircraft is pictured at Harwell around the time of its first flight. The Rotol propeller is installed but the 20 mm cannons are not.

The British Air Ministry doubted the quick delivery of the two MB3 prototypes still on order and was agreeable to a contract change. They authorized the construction of a single prototype of the new aircraft design designated MB5. The MB5 was given serial number R2496, which was originally allocated to the second and never-built MB3 aircraft. The third MB3 prototype was cancelled.

The Martin-Baker MB5 was officially designed to the same Air Ministry Specification (F.18/39) as the MB3. Also, the aircraft’s construction closely followed the methods used on the MB3. The aircraft’s fuselage was made of a tubular steel frame with bolted joints. Attached to the frame were formers that gave the fuselage its shape. Aluminum skin panels were attached to the formers, and detachable panels were used wherever possible. A rubber seal attached to the formers ensured the tight fit of the detachable skin panels, which were secured by Dzus fasteners. The large and easily removed panels helped simplify the aircraft’s service and maintenance.

Martin-Baker MB5 Rotol org tail rear

Again, the MB5 is shown at Harwell. The original vertical stabilizer and rudder were very similar to those used on the MB3. The inner gear doors are not installed on the aircraft.

The MB5’s wings were very similar to those used on the MB3, except that each housed only two 20 mm cannons with 200 rpg. All control surfaces used spring servo tabs; the rudder was fabric-covered, but all other control surfaces were metal-covered. The aircraft’s brakes, split flaps, and fully retractable landing gear were pneumatically controlled, and the air system operated at 350 psi (24.13 bar). The main wheels had a wide track of 15 ft 2 in (4.62 m). Two fuel tanks were housed in the aircraft’s fuselage: an 84 gallon (318 L) tank was positioned in front of the cockpit, and a 156 gallon (591 L) tank was positioned behind the cockpit. The cockpit was positioned directly above the wings and was enclosed with a bubble canopy. The cockpit had very good visibility, and its design was praised for the excellent layout of gauges and controls. The three main gauge clusters hinged downward for access and maintenance.

The MB5 was powered by a Rolls-Royce Griffon 83 engine capable of 2,340 hp (1,745 kW) with 25 psi (1.72 bar) of boost and 130 PN fuel. The engine originally turned a six-blade Rotol contra-rotating propeller, but by late 1945, a 12 ft 6 in (3.81 m) de Havilland contra-rotating unit was installed. A small scoop under the spinner brought in air to the Griffon’s two-speed, two-stage supercharger. The intercooler, radiator, and oil cooler were arranged, in that order, in a scoop under the fuselage. This arrangement provided some heat to the oil cooler when the engine was first started and prevented the oil from congealing and restricting the flow through the cooler.

Martin-Baker MB5 2nd tail

An intermediate modification to the MB5’s tail involved a more vertical leading edge that increased the fin’s area. This version of the tail did not last long before the completely redesigned unit was installed. The aircraft still has the Rotol propeller.

The aircraft had a 35 ft (10.7 m) wingspan, was 37 ft 9 in (11.5 m) long, and was 14 ft 4 in (4.4 m) tall. The MB5 had a maximum speed of 395 mph (636 km/h) at sea level, 425 mph (684 km/h) at 6,000 ft (1,829 m), and 460 mph (740 km/h) at 20,000 ft (6,096 m). Normal cruising speed was 360 mph (578 km/h) at 20,000 ft (6,096 m). The aircraft stalled at 95 mph (153 km/h) clean and at 78 mph (126 km/h) with flaps and gear extended. The MB5 had an initial rate of climb of 3,800 fpm (19.3 m/s) and could reach 20,000 ft (6,096 m) in 6.5 minutes and 34,000 ft (10,363 m) in 15 minutes. The MB5’s service ceiling was 40,000 ft (12,192 m), and it had a range of around 1,100 miles (1,770 km). The aircraft had an empty weight of 9,233 lb (4,188 kg), a normal weight of 11,500 lb (5,216 kg), and an overload weight of 12,090 lb (5,484 kg).

Construction of the MB5 started in 1943, and some components (possibly the wings and tail) of the second MB3 prototype were used in the MB5. The work on the aircraft was delayed because of other war work with which Martin-Baker was involved. In addition, Martin continued to refine and tinker with the MB5’s design, much to the frustration of the Air Ministry. However, the Air Ministry decided that Martin was going to do whatever he thought was right and that the best course of action was to leave him alone; the MB5 would be done when Martin decided it was done.

Martin-Baker MB5 dH front

The MB5 pictured close to its final form. The de Havilland propeller, inner gear doors, and taller vertical stabilizer and rudder have been installed. Note the smooth lines of the cowling. The position of the cockpit gave a good view over the aircraft’s nose and wings.

Captain Baker was Martin-Baker’s only test pilot and was never replaced. As the MB5 neared completion in the spring of 1944, Rotol test pilot (Leslie) Bryan Greensted was loaned to fly the aircraft. On 23 May 1944, the MB5 was disassembled and trucked from Martin-Baker’s works in Denham to the Royal Air Force (RAF) station in Harwell. The aircraft was reassembled and underwent some ground runs. Later that same day, Greensted took the MB5 aloft for its first test flight. To disassemble, transport, reassemble, and flight test an aircraft all in one day speaks to the MB5’s impressive design.

Greensted was not overly impressed with the aircraft’s first flight, because the MB5 exhibited directional instability; in fact, he said the aircraft “was an absolute swine to fly.” Martin listened intently to Greensted’s comments and immediately went to work on a solution. The increased blade area of the contra-rotating propellers had a destabilizing effect when coupled with the MB3 tail that was originally used on the MB5. To resolve the issue, Martin designed a taller vertical stabilizer and rudder, which were fitted to the MB5. The change took six months for Martin to implement, but when Greensted flew the aircraft, he was impressed by its performance and handling. In addition, a new horizontal stabilizer was fitted, but it is not known exactly when this was done. From its first flight until October 1945, the MB5 accumulated only about 40 flight hours. Martin-Baker had been informed around October 1944 that no MB5 production orders would be forthcoming, given that the war was winding down, and any production aircraft would most likely enter service after the war was over.

Martin-Baker MB5 dHf

The MB5 undergoing maintenance. A large panel has been removed from under the aircraft, and one of the inner gear doors has also been removed. Note the Dzus fasteners on the cowling and that the spinner is now painted black. The small scoop under the spinner delivered air to the engine’s supercharger.

Some sources state the MB5 was prepared for a speed run in the fall of 1945. The Griffon engine was boosted to produce 2,480 hp (1,849 kW), and the aircraft reached 484 mph (779 km/h) on a measured course near Gloucester. However, the speed record claim seems highly doubtful. On 29 October 1945, the MB5 was one of the aircraft exhibited at the Royal Aircraft Establishment (RAE) Farnborough. It was the only aircraft present that had contra-rotating propellers. While Greensted was demonstrating the aircraft before Winston Churchill and RAF officials, the Griffon engine failed. With his vision obscured by oil and some smoke in the cockpit, Greensted jettisoned the canopy. The canopy flew back and struck the tail, but Greensted was able to land the MB5 without further damage.

The MB5 had accumulated around 80 flight hours by the time it was handed over to the Aeroplane and Armament Experimental Establishment (A&AEE) at Boscombe Down. In March, April, and May 1946, the MB5 was flown by various pilots, and the aircraft’s performance and handling characteristics were well praised, but it was noted that the MB5’s acceleration and its roll rate were not quite on par with contemporary fighters. Overall, the tests showed that the MB5 was an excellent aircraft and that it was greatly superior from an engineering and maintenance standpoint to any other similar type. The MB5 was back at RAE Farnborough for an exhibition in June 1946. During the show, Polish Squadron Leader Jan Zurakowski flew the aircraft in a most impressive display and later stated that the MB5 was the best airplane he had ever flown.

Martin-Baker MB5 show

The MB5 was present at RAE Farnborough in October 1945. The display featured the latest British aircraft and several captured German aircraft. In the foreground is a Supermarine Spiteful and the MB5, with its 20 mm cannons installed. Other visible British aircraft include a Blackburn Firebrand, Bristol Brigand, Fairey Firefly, and Fairey Spearfish. Visible German aircraft include a Dornier Do 335, Fieseler Fi 103, Junker Ju 188, a pair of Focke-Wulf Fw 190s, and a Messerschmitt Bf 109. Many other British and German aircraft were present at the display.

The MB5 was flown sparingly until a number of flights were made toward the end of 1947. Wing Commander Maurice A. Smith flew the aircraft during this time and highly regarded the MB5’s layout and performance. From mid-November to the end of 1947, the MB5 was loaned to de Havilland at Hatfield for propeller testing. In 1948, the aircraft returned to RAE Farnborough, where it was flown by legendary pilot Captain Eric ‘Winkle’ Brown. Although Brown was slightly critical of the aircraft’s lateral handling qualities, he said the MB5 was an outstanding aircraft and that he had never felt more comfortable in a new aircraft.

On 5 May 1948, the MB5 was sent to the Air Ministry Servicing Development Unit at RAF Wattisham. There, it served as a training airframe until it was moved to RAF Bircham Newton around 1950. Reportedly, the MB5 was used as a ground target until its battered remains were burned in 1963—an inglorious end for such a fine aircraft.

Martin-Baker MB5 takeoff

The MB5 taking off from Chalgrove in 1948 with Wing Commander Maurice A. Smith at the controls. The MB5’s flaps did not have any intermediate positions—they were either up or down. The 20 mm cannons have been removed. Note the belly scoop’s outward similarity to the scoop used on the P-51 Mustang.

The Martin-Baker MB5 is one of a handful of aircraft that demonstrated superlative performance and flight qualities yet never entered production due to the end of World War II and the emergence of jet aircraft. It is quite impressive that the MB5 was created by a small firm that produced a total of four outstanding aircraft—each being a completely different model. Despite the quality of Martin-Baker’s aircraft and their best efforts to enter the aircraft manufacturing business, the MB5 was the company’s last aircraft. Martin-Baker turned their attention to other aircraft systems and became a pioneer and world leader in ejection seat technology.

An MB5 replica has been under construction by John Marlin of Reno, Nevada for a number of years. Although not an exact copy, Marlin’s reproduction is a labor of love intended to commemorate one of the most impressive aircraft of all time and to honor all who created the original MB5.

Martin-Baker MB5 Martin

James Martin is pictured in front of his masterpiece, the MB5. Martin-Baker’s aircraft never found success; however, the company’s ejection seats have saved thousands of lives and are still in production.

Sources:
RAF Fighters Part 2 by William Green and Gordon Swanborough (1979)
British Experimental Combat Aircraft of World War II by Tony Buttler (2012)
Wings of the Weird & Wonderful by Captain Eric ‘Winkle’ Brown (1983/2012)
Sir James Martin by Sarah Sharman (1996)
“The Martin-Baker M-B V” Flight (29 November 1945)
“M-B V in the Air” by Wing Commander Maurice A. Smith, Flight (18 December 1947)
“Martin-Baker Fighters,” by Bill Gunston, Wings of Fame Volume 9 (1997)
The British Fighter since 1912 by Francis K. Mason (1992)
http://johnmarlinsmb5replica.mysite.com/index_1.html

Isotta Fraschini Zeta rear

Isotta Fraschini Zeta X-24 Aircraft Engine

By William Pearce

In 1900, Cesare Isotta and Vincenzo Fraschini formed Isotta Fraschini (IF) in Milan, Italy. The firm originally imported automobiles, but began manufacturing its own vehicles by 1904. In 1908, IF started experimenting with aircraft engines and began producing them by 1911. The company went on to build successful lines of air-cooled and water-cooled engines. In the early 1930s, IF experienced financial issues caused in part by the great depression. In 1932, the Italian aircraft manufacturer Caproni purchased IF and continued production of automobiles and engines (both aircraft and marine).

Isotta Fraschini Zeta front

The Isotta Fraschini Zeta used many components from the Gamma V-12 engine. The air-cooled, X-24 Zeta had its cylinder banks at 90 degrees, and cooling the rear cylinders proved to be a problem. (Kevin Kemmerer image)

In the late 1930s, IF developed a pair of inverted, 60 degree, V-12, air-cooled engines. The first of the engines was the Gamma. The Gamma had a 4.92 in (125 mm) bore and a 5.12 in (130 mm) stroke. The engine displaced 1,168 cu in (19.1 L) and produced 542 hp (404 kW) at 2,600 rpm. The second engine was the Delta; it had the same architecture as the Gamma but had a larger bore and stroke of 5.20 in (132 mm) and 6.30 in (160 mm) respectively. The Delta displaced 1,603 cu in (26.3 L) and produced 790 hp (589 kW) at 2,500 rpm.

In 1939, the Ministero dell’Aeronautica (Italian Air Ministry) worked to import Daimler-Benz aircraft engines from Germany and obtain licenses for their production. IF decided to design an engine powerful enough to compete with the Daimler-Benz engines or replace them if sufficient quantities could not be imported.

To speed engine development, IF created the new engine using as much existing technology as possible. Essentially, two Gamma engines were mounted on a common crankcase in an X configuration to create the new engine, which was called the Zeta. The use of air-cooling and a single crankshaft simplified the design of the 24-cylinder Zeta engine.

Isotta Fraschini Zeta rear

All of the Zeta’s accessories were driven at the rear of the engine. A camshaft housing spanned all of the cylinders for one cylinder bank. Note the two spark plug leads for each cylinder extending from the top of the camshaft housing. The pipes for the air starter can been seen on the upper cylinder bank. (Kevin Kemmerer image)

The Isotta Fraschini Zeta was made up of an aluminum crankcase with four cylinder banks, each with six individual cylinders. All cylinder banks were positioned 90 degrees from one another. Each air-cooled cylinder was secured to the crankcase by ten bolts, and the cylinder’s steel liner extended into the crankcase. Each cylinder had two spark plugs that were fired by magnetos positioned at the rear of the cylinder bank.

Each cylinder had one intake and one exhaust valve. Mounted to the top of each bank of cylinders was a camshaft housing that contained dual overhead camshafts. A vertical shaft at the rear of the cylinder bank directly drove the exhaust camshaft. A short cross shaft drove the intake camshaft from the exhaust camshaft. The crankshaft was supported by seven plain bearings, and each connecting rod served four cylinders via a master rod and three articulating rods.

An accessory section at the rear of the engine drove the magnetos, vertical drives for the camshafts, and a single-stage supercharger. The supercharger forced air through intake manifolds between the upper and lower cylinder Vees. The exhaust gases were expelled from the cylinders via individual stacks between the left and right cylinder Vees. A pressurized air starting system was used, and the engine had a compression ratio of 6.5 to 1. The Zeta maintained the 4.92 in (125 mm) bore and 5.12 in (130 mm) stroke of the Gamma. The Zeta displaced 2,336 cu in (38.3 L) and produced 1,233 hp (919 kW) at 2,700 rpm. The engine was around 68 in (1.73 m) long, and 39 in (1.00 m) wide and tall. The Zeta weighed approximately 1,675 lb (760 kg).

Caproni F6Z IF Zeta

The Caproni Vizzola F.6MZ was the only aircraft to fly with a Zeta engine. The close-fitting cowl can be seen bulging around the engine’s cylinder banks, and the removed panels show just how tight of a fit the cowling was. Note the gap around the propeller for cooling air.

The Zeta RC45 was first run on 28 February 1941, and development was slowed due to various design issues. The engine was also having trouble making the forecasted output, with only around 1,085 hp (809 kW) being achieved. As development progressed, many of the issues were resolved, but the engine still lacked power. In May 1943, the Zeta RC24/60 with a two-speed supercharger was run, but the engine was not able to pass its type test. A number of aircraft were considered for conversion from their initial engines to the Zeta, but serious progress was made on only two aircraft.

The Caproni Vizzola F.6M was an all-metal aircraft based on the Caproni Vizzola F.5 but powered by a 1,475 hp (1,100 kW), liquid-cooled, Daimler-Benz DB 605 engine. While the F.6M was being developed, the design of a second version of the aircraft powered by a Zeta RC45 engine was initiated on 7 October 1941. The new design was called F.6MZ (or just F.6Z). The Zeta-powered aircraft was ordered on 16 June 1942, and it was assigned serial number (Matricola Militare) MM.498. The engine change came about because reliable deliveries of the DB 605 and its license-built contemporary, the FIAT RA 1050, could not be assured.

Progress on the Caproni Vizzola F.6MZ was delayed because of the engine. While the F.6M first flew in September 1941, it was not until 14 August 1943 that the F.6MZ took flight. The F.6MZ had a tight-fitting cowling that bulged around the engine’s four valve covers, and four rows of short exhaust stacks protruded from the cowling. Cooling air was taken in from around the spinner, and the air was expelled via an annular slot at the rear of the cowling. An oil cooler was housed in a chin radiator below the cowling.

Caproni Vizzola F6Z

The F.6MZ was first flown on 14 August 1943. The two rows of exhaust stacks can be seen near the cylinder bank bulges. The cooling air exit flaps can just be seen at the rear of the cowling.

First flown by Antonio Moda, the F.6MZ had an estimated top speed of 391 mph (630 km/h), some 37 mph (60 km/h) faster than the F.6M. This speed seems optimistic, considering the Zeta had an output of at least 225 hp (168 kW) less than the DB 605 and that the F.6MZ could not have produced significantly less drag or have been much lighter than the F.6M. The Zeta engine experienced overheating issues throughout the flight test program—the rear cylinders did not have sufficient airflow for proper cooling. Some modifications were made, but further flight tests were halted with Italy’s surrender on 8 September 1943. Two F.6MZ aircraft were ordered, but only the first prototype was built.

In October 1941, Regia Aeronautica (Italian Royal Air Force) requested that Reggiane (Officine Meccaniche Reggiane) replace the DB 605 / FIAT RA 1050 in its RE 2005 Sagittario fighter with the IF Zeta RC24/60. Reggiane was another company owned by Caproni. The Zeta-powered aircraft, developed after the RE 2005, was the Reggiane RE 2004, and seven examples were ordered. Although Reggiane was less enthusiastic about the Zeta than Caproni Vizzola, they did work on designing a firewall-forward engine package.

Isotta Fraschini Zeta SM79

These four images show the Zeta RC24/60 engine installed in the nose of a SM.79. Once tested, this installation would be applied to the Reggiane RE 2004. Note how the exhaust stack arrangement was completely different from that used on the F.6MZ.

A Zeta engine was not delivered to Reggiane until 1943. At the time, Reggiane was building Savoia-Marchetti SM.79 Sparviero three-engined bombers. One SM.79 was modified to have the Zeta engine installed in the nose position. This would enable the engine to be flight tested, and the cooling characteristics of the cowling configuration could be evaluated before the engine was used in the RE 2004. Compared to the F.6Z cowling, the Reggiane cowling had a larger diameter but was a cleaner design. Again, cooling air was brought in from around the spinner and exited through an annular slot at the rear of the cowling, and an oil cooler was positioned below the cowling. The Reggiane installation used exhaust stacks that ended with two close rows along the sides of the cowling. It appears that the Italian surrender occurred before the Zeta engine was ever flown in the SM.79. In fact, the Zeta RC24/60 was never cleared for flight, and the engine used in the SM.79 was most likely a mockup without all of its internal components. Although never built, the RE 2004 had an estimated top speed of 385 mph (620 km/h), 36 mph (58 km/h) slower than the RE 2005. At 7,117 lb (3,228 kg), the RE 2004 was 842 lb (382 kg) lighter than the RE 2005.

IF also designed the Sigma, a larger X-24 engine using cylinders and other components from the inverted, V-12, air-cooled Delta. The Sigma had a 5.20 in (132 mm) bore and 6.30 in (160 mm) stroke. The engine displaced 3,207 cu in (52.5 L) and had an estimated output of 1,578 hp (1,178 kW) at 2,400 rpm. The Sigma was never built, but its approximate dimensions were 82 in (2.08 m) long, and 45 in (1.15 m) wide and tall. The engine weighed around 2,160 lb (980 kg).

Isotta Fraschini Zeta SM79 cowling

The Zeta installation for the RE 2004 (as seen on the SM.79) was fairly clean but somewhat spoiled by the large oil cooler under the cowling. Note the cooling air exit gap at the rear of the cowling.

Sources:
https://it.wikipedia.org/wiki/Isotta_Fraschini_Zeta
Tutti gli aerie del Re by Max Vinerba (2011)
Italian Civil and Military Aircraft 1930-1945 by Jonathan W. Thompson (1963)
I Reggiane dall’ A alla Z by Sergio Govi (1985)
The Caproni-Reggiane Fighters 1938-1945 by Piero Prato (1969)
Ali E Motori D’Italia by Emilio Bestetti (1939)
Isotta Fraschini: The Noble Pride of Italy by Tim Nichols (1971)

Schwerer Gustav firing test

Krupp 80 cm Kanone Schwerer Gustav (Dora) Railway Gun

By William Pearce

In the 1930s, France constructed the Maginot Line, which was a series of fortifications and obstacles intended to protect the country against invasion from the east (Germany). The Maginot Line was to serve as an impenetrable wall of defense. Naturally, when one country develops a new defensive technology, other countries rush to develop a way to defeat that technology.

Schwerer Gustav firing test

The Krupp 80 cm Kanone (E) Schwerer Gustav / Dora being readied for a test firing on 19 March 1943 at Rügenwalde, Germany. Albert Speer (right), Adolf Hitler (second from right), and a number of other officials observed the firing. Hitler referred to the impractical gun as “meine stählerne faust (my steel fist).”

After studying details of Maginot Line fortifications that were published in French newspapers, it became apparent to German Wehrmacht (combined armed forces) planners that they did not possess any weapon capable of penetrating the fortifications. In 1935, the Wehrmacht requested Friedrich Krupp AG (Krupp), a heavy industry conglomerate in Essen, Germany, to prepare ballistics reports for guns firing 27.6, 31.5, 33.5, and 39.4 in (70, 80, 85, and 100 cm) shells. The goal was to fire the gun outside of the enemy’s artillery range and be able to penetrate 23 ft (7 m) of reinforced concrete or 3 ft (1 m) of steel armor. The Krupp factory dutifully ran the calculations and supplied the requested information but took no further action.

In March 1936, Adolf Hitler visited the Krupp factory and asked Gustav Krupp (von Bohlen und Halbach), head of the Krupp organization, what type of weapon was needed to smash through the Maginot Line. Krupp, recalling the recent report, was able to answer Hitler’s question in some detail. Krupp explained that a 33.5 in (80 cm) railway gun could be constructed and would be able to defeat the Maginot Line. After Hitler’s visit, Krupp directed his design staff to begin the layout of such a weapon. Erich Müller was the head of the artillery development department at Krupp and began working on the gun’s design.

Schwerer Gustav cradle assymbly

Nicknamed Dora by its crew, the massive gun was broken down into 25 pieces and transported by rail to its firing location. Two gantry cranes were used to reassemble the gun. Here, the cradle is being positioned into the carrier. Note the three normal railroad tracks and the special track for the cranes.

In early 1937, Krupp met with Hitler and presented him with the design for the 33.5 in (80 cm) railway gun. Hitler approved of what he saw, and the German Army High Command (Oberkommando des Heeres) commissioned Krupp to build three guns under the designation 80 cm Kanone (E). However, the guns quickly became known as Schwerer Gustav (Heavy Gustav), named after Gustav Krupp. Hitler wanted the first gun to be ready by March 1940.

The Schwerer Gustav was an absolutely huge weapon. The rifled barrel consisted of two halves, with the rear half covered by a jacket. The complete barrel was 106 ft 7 in (32.48 m) long, and its rifling was .39 in (10 mm) deep. Attached to the rear of the barrel was the cradle and breechblock. Mounted to the cradle were four hydraulic recoil absorbers. Trunnions held the gun’s cradle in two huge carriers and enabled the barrel to be elevated from 0 to 65 degrees. Each carrier was supported by four railroad trucks: two in the front and two in the rear. Each of the eight trucks was made up of five axles, giving the Schwerer Gustav a total of 80 wheels that were carried on two parallel sets of railroad tracks. The gun used a diesel-powered generator to provide power to run its systems. The Schwerer Gustav was 155 ft 2 in (47.30 m) long, 23 ft 4 in (7.10 m) wide, and 38 ft 1 in (11.60 m) tall. The barrel, cradle, and breech weighed 881,848 lb (400,000 kg), and the complete gun weighed 2,976,237 lb (1,350,000 kg).

Schwerer Gustav assymbly tracks

This image gives a good view of the tracks needed to assemble the Schwerer Gustav. One pair of D 311 locomotives is positioned in front of the gun.

In addition to needing parallel tracks, the Schwerer Gustav required its track to be curved up to 15 degrees. The gun had no built-in ability to traverse, so horizontal aiming (azimuth) was accomplished by moving the entire gun along the curved track. Extra bracing was added to the inside rail of both tracks along the shooting curve. This bracing helped prevent the tracks from being damaged due to the gun’s recoil. A massive effort was needed to transport and set up the Schwerer Gustav for firing.

The gun was broken down and transported on 25 freight cars, which did not include crew or supplies. Near where the gun was to be deployed, a spur line was laid from the main rail line. Three parallel tracks were then laid where the Schwerer Gustav was to be assembled. Two of the tracks supported the gun, and the third track allowed for parts and equipment to be brought in. A single rail was laid on both sides of the three parallel tracks. These widespread rails were for two gantry cranes to take parts from the third track and move them in position to assemble the Schwerer Gustav. Two parallel tracks extended from the assembly point to the firing position of the Schwerer Gustav. Dirt was piled up high on both sides of the double track to protect the gun from attack and allow it to be covered by camouflage netting. It took around 250 men 54 hours to assemble the Schwerer Gustav, and it took weeks for 2,000 to 4,500 men to lay the needed tracks and prepare the gun’s firing position. In addition, two Flak (Flugabwehrkanone or air defense cannon) battalions were needed to protect the gun from an aerial assault.

Schwerer Gustav captured shell

Allied soldiers pose in front of a captured projectile (left) and an obturation case (right). The projectile had a ballistic nose cone made of aluminum.

Krupp built special diesel-electric locomotives to move the Schwerer Gustav into firing position and to transport supplies. These locomotives were designated D 311, and two were paired together to act as a single unit, for a total of four engines to move the gun. Each locomotive was powered by a 940 hp (700 kW) six-cylinder MAN diesel engine. The engine ran a generator that provided power to traction motors mounted on the locomotive’s bogies. Ammunition was delivered via the twin rails behind the Schwerer Gustav. Hoists on the back of the gun would lift the ammunition to the firing deck. The shell was hoisted up one side of the gun, and the powder bags and a brass obturation case were hoisted up the other side. A hydraulic ram loaded the shell into the breach, followed by the powder bags and the case. Once loaded, the gun was raised into firing position. It took 20 to 45 minutes to load the gun and prepare it for firing. Only 14 to 16 shots could be fired each day.

Two types of shells were fired from the Schwerer Gustav: armor piercing (AP) and high explosive (HE). The AP rounds were 11 ft 10 in (3.6 m) long and were fired with 4,630 lb (2,100 kg) of propellant. The AP round was made of chrome-nickel steel. It weighed 15,653 lb (7,100 kg) and carried 551 lb (250 kg) of explosives. The AP shell had a muzzle velocity of 2,362 fps (720 m/s) and a maximum range of 23.6 miles (38 km). At maximum range, the AP projectile reached an altitude of around 39,370 ft (12 km) and was in the air for two minutes. The HE ammunition was around 13 ft 9 in (4.2 m) long and was fired with 4,938 lb (2,240 kg) of propellant. The HE rounds weighed 10,582 lb (4,800 kg) and carried 1,543 lb (700 kg) of explosives. The HE shell had a muzzle velocity of 2,690 fps (820 m/s) and a maximum range of 29.2 miles (47 km). Upon impact, the HE projectile created a crater some 33 ft (10 m) wide and deep. The muzzle velocity for both the AP and HE shells was over twice the speed of sound, and both were fitted with an aluminum alloy ballistic nose cone. Spotter aircraft were used to direct the gun’s fire and assess the results.

Construction of the Schwerer Gustav started in the spring of 1937, but forging the huge and complex barrel resulted in serious delays. By 1939, Alfried Krupp (von Bohlen und Halbach) began to take over company leadership from his father, whose health had begun to fail. In late 1939, testing started on sample components, and the gun’s AP projectile was able to successfully penetrate 23 ft (7 m) of concrete or 3 ft (1 m) of steel. It was obvious that the Schwerer Gustav would not be ready by the March 1940 deadline Hitler had requested.

Schwerer Gustav hoists

Shells and propellant for the gun were delivered by rail and hoisted up to the firing deck. The shell is on the far side, and the case with powder bags is in front of it (to the right). It took 20 to 45 minutes to reload the gun and prepare it for firing.

In May 1940, Germany invaded Belgium and France. Since the Maginot Line ended at Belgium, rather than extending to the English Channel, Germany was able to simply go around the static fortifications and enter France. On 25 June 1940, France surrendered to Germany.

With the fall of France, the Schwerer Gustav was no longer needed, but discussions ensued regarding other fortifications that the gun could be used against. Many in the Wehrmacht felt the gun was impractical and not worth the resources its construction consumed, let alone the manpower needed to deploy the gun. However, the Schwerer Gustav had become one of Hitler’s personal projects, so its development continued. Alfried Krupp hosted Hitler for a test firing during the gun’s acceptance trials in early 1941 at Rügenwalde, Germany (now Darłowo, Poland). Further tests and development continued through 1941. Some sources indicate that 250 rounds were fired from the gun during its testing.

Schwerer Gustav firing position

The gun was positioned on a shooting curve to allow for horizontal aiming. Rectangular braces were positioned on both sides of the inner rails to protect the tracks from the forces of firing the gun.

On 8 January 1942, Schwere Artillerie-Abteilung (E) 672 (Heavy Artillery Division E 672) was established with 1,420 men and with Oberst (Colonel) Robert Böhm as its commander. The unit was formed to deploy the Schwerer Gustav. As the artillerymen worked on the gun, they called it “Dora,” and the nickname stuck. From that time on, the gun was typically referred to as Dora, rather than Schwerer Gustav. The different names led to some confusion regarding how many guns were built and when they were used. German sources typically indicate that Dora was a nickname from the artillerymen and that only one gun was ever deployed. However, many English sources state that Gustav and Dora were the first and second guns built and that the Dora gun was named in honor of Erich Müller’s wife.

In February 1942, the division was sent to Bakhchisaray in the Crimean Peninsula, then part of the Soviet Union. The gun was to be used on the port city of Sevastopol, 18.6 miles (30 km) southwest of Bakhchisaray. Sevastopol had been under siege by German forces since November 1941. Five separate trains were used to transport the gun, the division, ammunition, supplies, and workshops to the deployment site. The Schwerer Gustav arrived in early March. In May, German troops and civilian workers laid a 1.2 mile (2 km) long access track to the firing site, followed by parallel tracks .75 miles (1.2 km) long for gun assembly and deployment. Once the track was ready, assembly of the gun commenced.

On 5 June 1942, the Schwerer Gustav fired its first round at Sevastopol, and 13 additional shots followed that day. On 6 June, the Schwerer Gustav achieved the highpoint of its career. An ammunition magazine at White Cliff suffered a direct hit from the Schwerer Gustav. The magazine was buried 98 ft (30 m) under Severnaya Bay and had 33 ft (10 m) of concrete protection. The AP round passed though the water, ground, and concrete before detonating the magazine. At least one ship was also sunk after being damaged by blast waves from the impact of nearby shells.

Schwerer Gustav firing

The Schwerer Gustav could fire a 15,653 lb (7,100 kg) AP shell 23.6 miles (38 km) or a 10,582 lb (4,800 kg) HE shell 29.2 miles (47 km). A spotter aircraft directed fire and assessed the results.

The gun was used on three additional days before its ammunition was exhausted. The Schwerer Gustav fired a total of 48 shells at the city, and its barrel had become worn. Some sources claim that the barrel had a 300-round life and was the same one that had fired the 250 test rounds. Other sources state the barrel was new and should have been able to fire 100 shots before it became worn, but signs of wear were seen after as few as 15 shots. Regardless, the Schwerer Gustav’s barrel was replaced with a spare, and the original barrel was transported back to Germany for repairs. Of the 48 rounds fired, only 10 fell within 197 ft (60 m) of their target, with the most off-target shot landing 2,428 ft (740 m) from its intended point of impact. However, each huge shell caused massive damage all around its impact site.

A few weeks after Sevastopol fell on 4 July 1942, Gustav Krupp gave the first Schwerer Gustav to Hitler as a personal gift and a sign of his support and allegiance to the Third Reich. The Krupp company would only accept payment for subsequent guns. The Schwerer Gustav was moved and redeployed for a planned offensive against Leningrad, which was also under siege. The gun had been assembled and placed in firing position, but its planned use was cancelled. The Schwerer Gustav was disassembled and taken back to Rügenwalde.

The gun was overhauled, and an improved, lined barrel was fitted. A test firing on 19 March 1943 at Rügenwalde was attended by Hitler, Albert Speer, Alfried Krupp, and a number of other officials. Two shots were fired, with the second shell impacting 29.2 miles (47 km) away. The Schwerer Gustav was then disassembled and placed in storage near Chemnitz, Germany in September 1943. The gun remained there until 14 April 1945, when it was destroyed by German troops one day before US soldiers captured the area. Parts of the Schwerer Gustav were recovered by the Soviets and supposedly transported to Russia. The second Schwerer Gustav was reportedly completed but never deployed. In March 1945, it was moved from Rügenwalde to Grafenwöhr, Germany, where it was destroyed on 19 April 1945.

Schwerer Gustav shooting curve

While it was a powerful weapon, the Schwerer Gustav required a tremendous amount of resources for its construct and deployment. Its size and complexity severely limited where and when the gun could be deployed and also made it very susceptible to aerial attack.

Around November 1943, plans were initiated to use a cannon to shell Britain from across the English Channel. It was decided that the third Krupp 80 cm Kanone (E) would be built as the gun for this purpose. In order to send a shell 99 to 124 miles (160 to 200 km), a projectile 20.5 in (52 cm) in diameter and weighing 1,499 lb (680 kg) would be shot out of a barrel 157 ft (48 m) long. This gun was named Länger Gustav (Longer Gustav). The gun was damaged during a bombing raid while it was still under construction. Some components for the Länger Gustav were discovered at the Krupp factory in Essen by Allied troops in 1945.

In December 1942, Krupp proposed a self-propelled 80 cm Kanone (E) known as the Landkreuzer P. 1500 Monster. The P. 1500 used the same 31.5 in (80 cm) main gun as the Schwerer Gustav, but it also had two 5.9 in (15 cm) sFH 18.1 L/30 field guns and a number of 15 mm MG151/15 cannons. Powering the P. 1500 were four 2,170 hp (1,618 kW) nine-cylinder MAN M9V 40/46 diesel engines. The P. 1500 was 137 ft 10 in (42 m) long, 59 ft 1 in (18 m) wide, and 23 ft (7 m) tall. True to its name, the Monster weighed 3,306,930 lb (1,500,000 kg). Requiring a crew of over 100, the machine had an estimated top speed of 9.3 mph (15 km/h) and a range of 31 miles (50 km). The P. 1500 project was cancelled in 1943 by Albert Speer, the Minister for Armaments, before any serious work had been done.

After the war, Alfried Krupp and Erich Müller, the gun’s designer, were sentenced to 12 years in prison for crimes against humanity by participating in the plundering, devastation, and exploitation of occupied countries and by participating in the murder, extermination, enslavement, deportation, imprisonment, torture, and use for slave labor of German nationals, prisoners of war, and civilians who came under German control. Krupp was pardoned after three years, and Müller was released after four years.

Schwerer Gustav 1 destruction

The first Schwerer Gustav gun was destroyed by German troops on 14 April 1945 to prevent its capture by US forces. Some sources state that the gun was recovered by the Soviets. A US soldier poses in front of the gun’s cradle. The girders attached to the cradle were used for transporting and mounting the cradle to the rest of the gun. The circular pad behind the soldier is a trunnion mount.

While the Schwerer Gustav was mechanically a well-engineered weapon, its requirements for use made it very impractical and nearly useless. The Maginot Line was easily bypassed, rather than penetrated, calling into question why the Schwerer Gustav was needed in the first place. However, Hitler liked the gun and called it his “steel fist.” It was the type of grandiose weapon that Hitler felt displayed the technological superiority of the Third Reich.

No large pieces of the Schwerer Gustav guns remain. However, a number of inert projectiles and cases are preserved in various museums. After the war, the D 331 locomotives were redesignated V 188 and used to haul freight for the West German Railway (Deutsche Bundesbahn).

Schwerer Gustav 2 destruction

Germans destroyed part of the second Schwerer Gustav on 19 April 1945 to prevent its capture. A US soldier gives scale to the gun’s barrel. The second gun’s cradle, which was blown up, can be seen on the left.

Sources:
http://de.wikipedia.org/wiki/80-cm-Kanone_(E)
http://en.wikipedia.org/wiki/Schwerer_Gustav
http://ww2db.com/weapon.php?q=89
http://samilitaryhistory.org/vol124lw.html
http://html2.free.fr/canons/dora.htm
http://de.wikipedia.org/wiki/Wehrmachtslokomotive_D_311
http://www.modellbahn.com/37283.V188.html
http://www.e94114.de/V188.htm
http://www.militaryfactory.com/armor/detail.asp?armor_id=480
http://en.wikipedia.org/wiki/Landkreuzer_P._1500_Monster