Category Archives: Between the Wars

Curtiss XF6C-6 Page Navy Racer 18-08-1930

Curtiss XF6C-6 Page Navy Racer

By William Pearce

After World War I, it was clear that aircraft were vehicles with great potential, and not just playthings for the rich or eccentric. A rivalry built up between the United States Marine Corps, Navy, Army, and civilians as they each explored aviation in the 1920s. The military branches competed with each other in various races, with floatplanes switching to wheels for land-based races and wheeled aircraft switching to floats for sea-based races.

Curtiss XF6C-6 Page Navy Racer

The Curtiss XF6C-6 Page Navy Racer created for the 1930 Thompson Trophy Race.

US Marine Corps Captain Arthur H. Page flew his float-equipped Curtiss F6C-3 racer to victory in the Curtiss Marine Trophy Race on 31 May 1930, besting the rest of the field, which consisted entirely of Navy pilots. The F6C-3 was a member of the Curtiss Hawk family of biplane fighter aircraft, which had been steadily developed since the first Hawk was built for the Army in 1923. The F6C-3 had a fuselage and tail made of welded steel tubing and covered with fabric. The wings had a spruce structure and were fabric covered. Page’s F6C-3 (serial A-7147) had been cleaned up aerodynamically to achieve every bit of speed possible, and it averaged a race-record 164.08 mph (264.06 km/h).

Page knew he would need more speed from the F6C-3 if he were to have any chance in the inaugural Thompson Trophy Race, which would be held on 1 September 1930 during the National Air Races. In the 1929 National Air Races, civilian Doug Davis in the privately-built Travel Air “Mystery Ship” beat both the Army and Navy Hawk entries when he averaged 194.9 mph (313.7 km/h) over the course of the race. Page wanted to avenge this humiliating defeat and set a new standard of speed in the process. Page won the support of the Navy Bureau of Aeronautics, and Curtiss went to work in June 1930 to turn the F6C-3 (serial A-7147) into a pure air racer. This was the same aircraft in which Page won the Curtiss Marine Trophy Race.

Curtiss F6C-3 Marine Race Page

The Curtiss F6C-3 Hawk that Arthur Page flew to victory in the 1930 Curtiss Marine Trophy Race. For that race, the radiator intake was modified, and the radiator housing was faired back to the tail. The fuel filler cap and pilot’s headrest were also faired to improve the aircraft’s aerodynamics. This aircraft was extensively modified into the XF6C-6 racer.

The modifications made to the F6C-3 were so extensive that the aircraft was redesignated XF6C-6. With the exception of the tail, the XF6C-6 bore no resemblance to the F6C-3. The 450 hp (336 kW) Curtiss D-12 engine was removed and replaced by a supercharged 750 hp (559 kW) Curtiss Conqueror engine. The Conqueror had a 5-1/8 in. (130 mm) bore and a 6-11/32 in (161 mm) stroke. The engine’s total displacement was 1,570 cu in (25.7 L), and it turned an 8 ft (2.4 m), two-blade, steel, ground-adjustable propeller.

The aircraft’s lower wing was removed, and the upper wing was moved back several inches. The now-parasol wing was mounted to the fuselage on streamlined struts. The wing had a duralumin leading edge, and brass surface radiators made up most of its upper and lower surfaces. Coolant was taken from the engine and flowed through pipes installed in the front wing struts. The coolant then flowed into header tanks along the wing’s leading edge and through the surface radiators. At the rear of the wing, the coolant was collected and flowed back to the engine via pipes that ran through the rear struts.

Curtiss XF6C-6 Page Navy Racer 18-08-1930

The completed Curtiss XF6C-6 on 18 August 1930. Even though it is the same aircraft, the modifications have made it unrecognizable from its F6C-3 origins.

The wing radiators enabled the chin radiator to be discarded, and a very streamlined aluminum engine cowling was fitted over the Conqueror engine. The landing gear was housed in aerodynamic wheel pants and attached to the fuselage by a single streamlined strut. The XF6C-6’s cockpit had metal panels on each side and was partially enclosed by a cushioned cover positioned over the pilot’s head. The panels hinged down, and the cover hinged to the rear for pilot entry and exit. The aircraft’s fuselage was aerodynamically cleaned up and recovered.

The XF6C-6 racer is often referred to as the “Page Racer” or “Navy Page Racer.” The aircraft had a polished navy blue fuselage and lower wing surface, and the upper wing surface was yellow. The exposed brass of the surface radiators was polished. The aircraft had a wingspan of 31 ft 6 in (9.6 m), a length of 23 ft 0 in (7.0 m), and a height of 8 ft 11 in (2.7 m). The XF6C-6 had an empty weight of 2,600 lb (1,179 kg) and a loaded weight of 3,130 lb (1,420 kg). Its range was 270 mi (435 km). The XF6C-6 had a cruising speed of 200 mph (322 km/h) and an estimated top speed of 250 mph (402 km/h).

Curtiss XF6C-6 Page Navy Racer cockpit

This image of the XF6C-6 racer shows the hinged cockpit sides and cover. The aircraft has its Thompson Trophy Race number (27) applied, and no carburetor scoop is visible. Note the exposed wheels.

Construction for the XF6C-6 was rapid, and the aircraft was completed by mid-August. The initial flight testing went well, but some signs of flutter were encountered at high speeds. Originally, a louvered panel on top of the engine cowling supplied air to the engine’s carburetor. A raised scoop replaced the louvers before the Thompson Race. However, some sources indicate the scoop was discarded and the louvered panel was reinstalled for the actual race.

The aircraft made its public debut for the Thompson Trophy Races held at the Curtiss-Reynolds airport (later Naval Air Station Glenview and now a shopping center) south of Chicago, Illinois. Captain Page in the XF6C-6 was the only military entrant in the field of seven. The XF6C-6 was larger than the other Thompson Trophy racers, but it was also more powerful.

Page was the first airborne, followed by the other racers at 10 second intervals. By the time the last racer took off, Page had almost completed his first lap of the five mile (8 km) circuit. The XF6C-6 was obviously much faster than the other racers; the only question was whether or not it would last the 20 laps. By the third lap, Page began lapping the slower aircraft. Page turned lap after lap at well over 200 mph (322 km/h), and the XF6C-6 went on to lap the entire field.

Curtiss XF6C-6 Page Navy Racer rear scoop

This image shows the Curtiss XF6C-6 racer again with its race number, but the carburetor scoop is in place. Also visible is the hand crank (and its shadow) used to start the engine. Note how the aircraft’s seams have been taped over to reduce drag.

On the 17th lap, Page went high and turned inside the course as he neared the home pylon. The XF6C-6 never straightened from the turn; it smashed into the ground as the 75,000 spectators looked on. Page survived the crash and was taken to a hospital where he died from his injuries later that night. Fellow race pilot Jimmy Haizlip, who had just been lapped by Page, noted the XF6C-6’s propeller was barely turning before the ground impact. In addition, the ignition switch was found in the “Off” position. It is believed that Page had been slowly overcome by carbon monoxide fumes from the exhaust that built up in the tight cockpit. Although too late, he realized the situation and shut off the engine in an attempt to get fresh air. He then turned inside the course to seek a safe landing but became incapacitated and crashed. Unfortunately, carbon monoxide poisoning was a fairly common occurrence in early aviation, and Page was one of many aviators who succumbed to exhaust fumes in the cockpit.

The XF6C-6 had turned each lap between 207 and 219 mph (333 and 352 km/h) before the crash (some sources state the average speed was 219 mph / 352 km/h). Speed Holman in the Laid Solution went on to win the race at 201.91 mph (324.94 km/h). With the death of Captain Page, American military aircraft were no longer entered in air races until after World War II. Even then, civilian and military racers participated separately (primarily because of the military’s switch to jet aircraft).

Curtiss XF6C-6 Page Navy Racer front scoop

The XF6C-6 during an engine run-up. This image provides a good view of the carburetor scoop and taped seams. The bulges on top of the wing are expansion tanks for the surface radiators.

Sources:
Curtiss Aircraft 1907-1947 by Peter M. Bowers (1979/1987)
Racing Planes & Air Races 1909-1967 by Reed Kinert (1967)
– “Captain Page and the 1930 Thompson Trophy Race” by Jimmy Halzip The Golden Age of Air Racing (1963/1991)
Thompson Trophy Racers by Rodger Huntington (1989)
http://1000aircraftphotos.com/Contributions/Shumaker/9130.htm
https://www.mca-marines.org/leatherneck/1930/07/marine-wins-curtiss-trophy

Short Sarafand flight

Short S.14 Sarafand Flying Boat

By William Pearce

In 1928, H. Oswald Short of Short Brothers envisioned a larger follow-on to his Singapore II flying boat. He believed that Short Brothers could design and construct a streamlined flying boat that would be just as large as the 12-engine Dornier Do X (the largest aircraft at the time) but with better performance. This new aircraft was designated S.14, and Short Brothers prepared preliminary drawings to seek funding. After prolonged discussions, Short was able to gain the support of the British Air Ministry to fund the S.14 under specification R.6/28.

Short Sarafand flight

The Short Sarafand on its fourth flight, which took place on 10 July 1932, near Kingsnorth.

The Short S.14’s chief designer was Arthur Gouge. The aircraft was a large biplane flying boat capable of transatlantic service. The S.14’s six engines were placed between the wings in three tandem pairs, each pair sharing a streamlined nacelle. A 1/14th scale model was tested in the Royal Aircraft Establishment’s wind tunnel with satisfactory results, and construction of the aircraft began in mid-1931.

The equal-span, fabric covered wings were slightly swept. Because of the loads imposed on the large wings, their spars were made of stainless steel rather than duralumin (an aluminum alloy that incorporates copper, manganese, and magnesium for increased hardness). Toward the end of each lower wing was a wing tip float. The bottoms of the floats were made of stainless steel, but they also had provisions to mount a replaceable zinc plate. The zinc plate acted as an anode to prevent corrosion from occurring on the rest of the aircraft.

Short Sarafand mooring

The Sarafand moored on the River Medway by the Short Brothers shops in 1932. Note the streamlined engine nacelles for the Rolls-Royce Buzzard engines.

The upper and lower wings were joined by a series of struts, and the center struts also supported integral engine nacelles. Two Rolls-Royce Buzzard III engines were positioned back-to-back in each engine nacelle, and the radiators for the engines were housed below the engine nacelle. The Buzzard III engine had a 6.0 in (152 mm) bore, a 6.6 in (168 mm) stroke, and a total displacement of 2,239 cu in (36.7 L). Each of the six engines produced 825 hp (615 kW) at 2,000 rpm and 930 hp (699 kW) at 2,300 rpm. Each engine turned a wooden, fixed-pitch, two-blade propeller. Each front engine used a 15 ft (4.57 m) diameter propeller, and each rear engine used a 14 ft (4.27 m) diameter propeller.

The aircraft’s two-step hull was made of duralumin and had a planing bottom made of stainless steel. A large Flettner servo tab trailed behind and controlled the S.14’s rudder. The elevators had balancing airfoils on their upper and lower surfaces. An auxiliary fin was positioned on each side of the horizontal stabilizer, and their incidence could be altered by the pilot to trim out any yaw experienced from a dead engine.

Short Sarafand rear

The tail of the Sarafand showing the Flettner servo tab behind the rudder, the balancing fins on the elevator, and the auxiliary fins on the horizontal stabilizer. Note the rear gunner position behind the rudder and the extensive braces supporting the horizontal stabilizer. This photo was taken after the Sarafand’s planing bottom was reskinned with Alclad.

The S.14 was given the serial number S1589 and was eventually named the Sarafand. The aircraft had a wingspan of 120 ft (36.6 m), a length of 89.5 ft (27.3 m), and a height of 30.3 ft (9.2 m). The upper wing held 2,110 gallons (7,987 L) of fuel, and the lower wing held 1,272 gallons (4,825 L). Each of the Sarafand’s six engines had individual tanks for their 28.5 gallons (45.9 L) of water (for the cooling system) and 16 gallons (25.7 L) of oil. The Sarafand had an empty weight of 44,740 lb (20,293 kg) and a fully loaded weight of 70,000 lb (31,752 kg). The aircraft had a 1,450 mi (2,334 km) range and a 13,000 ft (3,962 m) ceiling. The Sarafand’s max speed was 153 mph (246 km/h).

The Sarafand was the world’s second largest aircraft at the time—the Do X retained its title as the largest. However, the aircraft was never intended as a commercial transport. The Sarafand was strictly for military use as a possible long ranger bomber or reconnaissance aircraft. While it is unlikely that guns were ever installed, the Sarafand did have a number of gun positions: one in the nose, two behind the wings in the upper fuselage, and one behind the tail. The aircraft’s crew of ten had ample accommodations in the Sarafand’s interior, including a ward-room, six folding bunks in various crew rooms, a galley, a maintenance area, and a lavatory. The crew stations were linked by a telephone intercom. A section of the upper rear fuselage could be removed to allow a spare engine to be loaded in the aircraft for transport, and a portable jib was carried to allow engine changes while the Sarafand was afloat. The pilot and copilot sat in tandem in a fully enclosed cockpit.

Short Sarafand taxi

The Short Sarafand maneuvers on the water before a test flight.

The aircraft was built in Rochester in the Short Brothers’ No. 3 riverside shop, but the shop was not tall enough to accommodate the Sarafand with its upper wings in place. As a result, the partially completed aircraft was launched on 15 June 1932 and taken down the River Medway to a shipyard where the upper wings were attached.

The completed Sarafand was relaunched on 30 June and flown for the first time later that day with John Parker as pilot and Oswald Short as copilot. Controls were found to be light and well balanced, and only minor adjustments were needed. A few other flights were made before the aircraft was demonstrated to the press on 11 July. For this flight, the Sarafand became airborne in 19 seconds, reached a top speed of around 150 mph (241 km/h), and flew for about 40 minutes.

Short Sarafand fly past

The Short Sarafand flies past the press assembled on the paddle steamer Essex Queen on 11 July 1932. Flying behind the Sarafand is a photo plane, and another flying boat can be seen on the water to the right.

The aircraft made several additional test flights and was delivered to the Marine Aircraft Experimental Establishment (MAEE) in Felixstowe on 2 August 1932. The MAEE found the Sarafand to have an excessive takeoff run when heavily loaded, vibration issues from the tractor and pusher propellers, and a tendency to porpoise on landing in certain conditions. The MAEE also believed the aircraft would have cooling issues if it were operated in warmer climates.

In late 1933, the stainless steel planing bottom was found to be corroded and was replaced with Alclad (corrosion-resistant aluminum sheeting). Further changes were made to the wing braces and hull to address the vibration and porpoising issues. The Sarafand was relaunched on 29 April 1934 and continued to be used for various experimental flights by the MAEE, although it spent much more time at its mooring than in the air. By 1936, the Sarafand and its biplane configuration were outdated, and the aircraft was scrapped. The Short S.14 Sarafand was really nothing more than an experimental aircraft that pushed the limits of aircraft design. It proved to be reliable and easy to fly, and it helped to pave the way for future large aircraft.

Short Sarafand shore

The Short Sarafand drawn up on shore and probably late in its life. Gone are the blue, red, and white stripes on the rudder, and the Buzzard engines have been fitted with updated exhaust manifolds.

Sources:
Shorts Aircraft since 1900 by C. H. Barnes (1967/1989)
British Flying Boats by Peter London (2003)
The Seaplane Years by Tim Mason (2010)
Jane’s All the World’s Aircraft 1934 by C. G. Grey (1934)
Jane’s All the World’s Aircraft 1935 by C. G. Grey and Leonard Bridgman (1935)
British Piston Aero-Engines and Their Aircraft by Alec Lumsden (1994)
– “The Short Sarafand” Flight (13 June 1935)

FIAT AS8 V-16 side

FIAT AS.8 Engine and CMASA CS.15 Racer

By William Pearce

Since 10 April 1933, Italy had enjoyed ownership of the 3 km absolute world speed record for aircraft. Warrant Officer Francesco Agello set the record at 423.824 mph (682.078 km/h) in the Macchi-Castodi MC.72 seaplane built for the Schneider Trophy Contest. The MC.72 was powered by a 24-cyllinder FIAT AS.6 engine. Agello went on to raise the record to 440.682 mph (709.209 km/h) on 23 October 1934 in another MC.72.

FIAT AS8 V-16 side

Side view of the FIAT AS.8 V-16 engine specifically designed for the CMASA CS.15 racer.

However, Germany captured the world speed record on 30 March 1939, when Hans Dieterle flew 463.919 mph (746.606 km/h) in the Heinkel He 100 (V8). Germany raised the record a month later on 26 April 1939, when Fritz Wendel traveled 469.221 mph (755.138 km/h) in the Messerschmitt Me 209 (V1).

Even before Dieterle’s record flight, the Italians had considered building an aircraft specifically for a new record attempt. FIAT, with the support of the Italian government, wanted to win the record back and had initiated an aircraft and engine design that was somewhat finalized before Wendel’s record flight. The new record aircraft was designed and built by Costruzioni Meccaniche Aeronautiche SA (CMASA), a FIAT subsidiary in Pisa. The engine would be designed and built at FIAT’s headquarters in Turin.

FIAT AS8 rear

A rear view of the FIAT AS.8 showing the valley between the engine’s banks. The small manifolds on each bank are to take the cooling water from the cylinders. They are installed backward in this photo; the outlet should be at the engine’s rear. The long intake manifold is reminiscent of the even-longer manifold used on the AS.6. The large port in the manifold elbow, seen just above the carburetor, is a relief valve to prevent over pressurization of the manifold (perhaps in the event of a backfire—a major issue in the early development of the AS.6).

The aircraft was designed by Manlio Stiavelli and was known as the Corsa (meaning Race) Stiavelli 15, or just CS.15. Lucio Lazzarino, an engineer at CMASA, analyzed and tested various aspects of the CS.15 design. The CS.15 was a small, mid-wing, all-metal aircraft with a very low frontal area. Its 29.5 ft (9.0 m) monospar wing had conventional flaps and ailerons. The cockpit was situated far aft on the 29.2 ft (8.91 m) fuselage and was faired into the long tail.

To keep the wing thin and the fuselage narrow, the main wheels of the CS.15 folded toward each other before retracting aft into the fuselage. The CS.15’s fuel tank was situated behind the engine, in front of the cockpit, and above the main landing gear well. Fuel capacity was very limited, and the CS.15 was only meant to have enough endurance to capture the speed record—about 30 minutes of flight time. The estimated empty weight of the CS.15 was 4,213 lb (1,910) kg, and its total weight was 5,000 lb (2,270 kg).

To power the CS.15, Antonio Fessia and Carlo Bona laid out the AS.8 (Aviazione Spinto 8) engine design at FIAT. The AS.8 was a completely new design but had many common elements with the AS.6 engine used in the MC.72. The AS.6 was designed by Tranquillo Zerbi, and Fessia had taken over Zerbi’s position at FIAT when he passed away on 10 March 1939. The AS.8 was a liquid-cooled engine with cylinders very similar to the AS.6’s, utilizing two intake and two exhaust valves actuated by dual overhead camshafts. The AS.6 and AS.8 shared the same 5.51 in (140 mm) stroke, but the AS.8’s bore was increased .08 in (2 mm) to 5.51 in (140 mm). Reportedly, the AS.6 and AS.8 used the same connecting rods and both engines were started with compressed air.

FIAT AS8 front

This view displays the four magnetos of the FIAT AS.8 just above the propeller gear reduction. Note the the air distribution valves driven by the exhaust camshafts for starting the engine. The outlet of the water pumps can be seen in the forward position, which differs from the first image on this page.

The AS.8 was unusual in many ways. Its two banks of eight individual cylinders were set at 45 degrees. The 16 cylinders gave a total displacement of 2,104 cu in (34.5 L). The cylinders had a 6.5 to 1 compression ratio. The single-stage supercharger was geared to the rear of the engine and provided pressurized air to the cylinders via a long intake manifold between the cylinder banks. The carburetors were mounted above the supercharger. Unlike the AS.6, which used independent coaxial propellers, the AS.8 featured contra-rotating propellers geared to the front of the engine at a 0.60:1 reduction. Two sets of two-blade propellers 7.2 ft (2.2 m) in diameter could convert the AS.8’s power into thrust for the CS.15. The engine weighed 1,742 lb (790 kg).

Nine main bearings were used to support the long crankshaft and to alleviate torsional vibrations. In addition, drives for the camshafts, magnetos, and water pumps were mounted at the front of the engine. Each cylinder bank had two magnetos to fire the two spark plugs per cylinder. The distributor valve for the air starter was driven from the front of the exhaust camshaft for each cylinder bank. The exhaust gases of the AS.8 were utilized to add propulsive thrust through specially designed exhaust stacks on each cylinder.

FIAT AS8 bank

A detailed view of the AS.8’s right cylinder bank. Each cylinder had one spark plug on the outside of the engine and one in the Vee. The pipe next to the spark plug is for the air starter. The manifold at the bottom fed cool water into the cylinder jacket. (Emanuele image via Flickr)

For cooling, pressurized water was drawn into a pump on each side of the engine, near its front. A manifold delivered the water to each cylinder on the outside of the bank. The water then flowed through the cylinders and exited their top into another manifold situated in the Vee of the engine. The heated water, still under pressure, was taken back to the CS.15’s tail, where it was depressurized and allowed to boil. The steam then flowed through the CS.15’s wings, where 80% of their surface area was used to cool the steam and allow it to condense back into water. The water was then re-pressurized and fed back to the engine. Engine oil was also cooled by surface cooling in the rear and tail of the aircraft.

CMASA CS15

A three-view drawing of the CMASA CS.15 racer. Note the thin wings, minimal frontal area, and main gear retraction.

By early 1940, full-scale mockups of various CS.15 components were built and the construction of the CS.15 was underway. Wind tunnel tests indicated the CS.15 would reach a speed of 528 mph (850 km/h). The AS.8 engine was running on the test stand at this time. During these tests, the AS.8 achieved an output of 2,500 hp (1,864 kW), but the engine was rated at 2,250 hp (1,678 kW) at 3,200 rpm. The engine accumulated tens of hours running on the test stand and encountered few, if any, major failures. It is not known how many AS.8 engines were built, but the number is thought to be very small. The AS.8 was also the starting point of another V-16 engine, the FIAT A.38.

After Italy entered World War II in June 1940, progress on the CS.15 and AS.8 continued but at a much reduced pace. The CS.15 was damaged in various air raids, and it was further wrecked by the Germans as they exited Italy in late 1943. Some believe that whatever remained of the CS.15 was taken to Germany, as the aircraft essentially disappeared. As for the AS.8 engine, one example survived the war and is on display (or in storage) at the Centro Storico Fiat (Fiat Historic Center) in Turin, Italy.

The AS.8 achieved a power output greater than 1 hp/cu in and 1 hp/lb—accomplishments that were sought after by engine designers around the world.

Sources:
MC 72 & Coppa Schneider Vol. 2 by Igino Coggi (1984)
Aeronuatica Militare Museo Storico Catalogo Motori by Oscar Marchi (1980)
World Speed Record Aircraft by Ferdinand Kasmann (1990)
Italian Civil and Military Aircraft 1930-1945 by Jonathan W. Thompson (1963)

Short Silver Streak

Short Swallow / Silver Streak

By William Pearce

H. Oswald Short and his brother Eustace founded Short Brothers in London, England in 1908. In 1916, they became acquainted with duralumin when their firm took over construction of two airships that used duralumin components. Duralumin is an aluminum alloy that incorporates copper, manganese, and magnesium for increased hardness. Fabric and wood were used to build aircraft at the time, but from his experience, Oswald believed that duralumin was a far superior building material for aircraft construction. A duralumin aircraft would be stronger than a wooden aircraft, and it would also be resistant to warping, fire, and rot.

Short Silver Streak

Factory photo of the Short Swallow / Silver Streak shortly after its completion in 1920. The aircraft’s riveted construction is evident in this image. Note the cargo compartment in front of the cockpit (between the upper wing’s cabane struts) is covered over.

Oswald extensively tested various duralumin-built components with the intent of using duralumin for aircraft construction. Many wondered whether or not duralumin would resist corrosion. To prove the metal was up to the task, Oswald affixed duralumin and mild-steel plates to a jetty so that they were exposed at low tide and submerged in the sea at high tide. After nine months, the duralumin had only light surface corrosion, while the steel plates had nearly rusted away.

Reassured of duralumin’s corrosion resistance, Oswald designed an all-metal aircraft in 1919. He sought funding from the British Air Ministry to build a prototype but was turned down because of the unproven duralumin construction. Short Brothers was so confident in duralumin’s merits that in 1920, at their own expense, they began constructing the aircraft Oswald designed. The aircraft was quickly completed and made its debut at the Olympia Air Show in London on 9 July 1920. Originally, the aircraft was named Swallow, but its name was changed to Silver Streak after the show.

Short Silver Streak Olympia

The Short Swallow (later renamed Silver Streak) on display at the Olympia Air Show in 1920, where the polished all-metal aircraft attracted a lot of attention.

The Short Swallow / Silver Streak was the first all-metal aircraft built in Great Britain; no wood or fabric was used. The structure of each wing was made up of two steel spars with duralumin ribs sweated on. The wings and tail were skinned with sheet aluminum riveted to their respective frames. The fuselage’s frame had an oval cross section and was made of duralumin. Duralumin sheets were riveted to the duralumin airframe to make up the aircraft’s skin. Thicker duralumin sheets were used around the cockpit, and the front of the fuselage was enclosed by a single duralumin sheet, making a fireproof bulkhead.

The Silver Streak was powered by a water-cooled, 240 hp (179 kW), straight, six-cylinder Siddeley Puma engine. The aircraft was designed for a pilot and 400 lb (181 kg) of cargo in front of the cockpit. However, modifications would easily allow the aircraft to carry a passenger in place of the cargo. The Silver Streak had a wingspan of 37 ft 6 in (11.4 m) and a length of 26 ft 5 in (8.1 m). It had an empty weight of 1,865 lb (846 kg) and a loaded weight of 2,870 lb (1,302 kg). The Silver Streak’s max speed was 125 mph (201 km/h), and it had a 450 mile (724 km) range.

The Silver Streak made quite an impression at the Olympia show. However, many remained skeptical of its duralumin construction. This skepticism led to the Silver Streak being refused its Certificate of Airworthiness. However, the British Air Ministry agreed to purchase the Silver Streak to evaluate its all-metal aircraft construction. The Silver Streak was first flown on 20 August 1920 by John Parker at the Isle of Grain in Britain. The thin aluminum wing and tail skins were found to lack the needed strength and were replaced with duralumin sheeting. The Sliver Streak took to the air again on 27 January 1921 and was delivered to the Royal Aircraft Establishment at Farnborough in February. During the flight to Farnborough, it was noted that the aircraft cruised at over 120 mph (193 km/h).

Short Silver Streak side

The Short Silver Streak after its delivery to Farnborough in February 1921. The cargo compartment has been converted to carry a passenger.

At Farnborough, the Silver Streak received the Air Ministry serial number J6854 and was flown on a few test flights through June 1921. Testing revealed the aircraft could climb to 10,000 ft (3,048 m) in just 11 minutes and had a top speed in excess of 125 mph (201 km/h). Pilots noted the Silver Streak’s quick acceleration, steadiness in the air, and ease of control. However, the test flying was very limited, and after June the aircraft was relegated to static testing.

Nothing was heard of the Silver Streak for over a year, and then the Air Ministry reported that it had tested the aircraft to destruction. During that time, no corrosion issues were encounter with the duralumin. In wing-loading tests, the wing failed just above its calculated ultimate stress level when a spar buckled. However, even with the buckled spar, the wing still possessed enough structural integrity for normal flight. The tail and rudder were separately tested and failed under a load far in excess of what a wooden tail and rudder could withstand. The fuselage survived a 2,000 lb-ft (2,712 N•m) torsion test with no visible distortion. The fuselage was then subjected to 100 hours of vibration tests which revealed no signs of cracks or loose rivets.

Satisfied with the results and believing that all-metal construction was sound, the Air Ministry ordered two prototypes of a Short two-seat fighter sea plane in January 1922. Financial concerns caused this order to be cancelled in June 1922. However, the Silver Streak was used as the basis for the Short Springbok, and its construction techniques were employed in future aircraft.

Short Silver Streak front

A good view of the Silver Streak illustrating how the Siddeley Puma engine was exposed to the airstream to aid cooling.

Sources:
Shorts Aircraft since 1900 by C. H. Barns (1967/1998)
British Prototype Aircraft by Ray Sturtivant (1995)
– “The Olympia 1920 Aero ShowFlight (22 July 1920)
– “Air Ministry Acquire Short ‘Silver Streak’Flight (24 February 1921)
– “Short Bros. and Metal ConstructionFlight (11 December 1924)

savoia-marchetti s64 take off

Savoia-Marchetti S.64 and S.64 bis

By William Pearce

Inspired by Charles Lindbergh’s New York to Paris transatlantic flight of 3,600 miles (5,800 km) in May 1927, Italian pilot Arturo Ferrarin discussed with Alessandro Marchetti the possibility of building an aircraft to set non-stop distance records. Ferrarin was an experienced long distance flyer, having flown from Rome to Tokyo in 1920. Marchetti was the chief designer for Savoia-Marchetti and had complete control of the aircraft’s design and configuration. What emerged from Marchetti’s drafting table was the S.64. The Italian Air Ministry supported the project as a way to demonstrate the capabilities of Italian aviation to the world; two S.64 aircraft were ordered in late 1927.

savoia-marchetti s64 take off

The Savoia-Marchetti S.64 taking off from Montecelio. The retractable radiator can be seen under the wing and just behind the fuselage nacelle.

The Savoia-Marchetti S.64 was an aircraft of a rather unorthodox configuration yet similar to Marchetti’s earlier flying boat design, the S.55. Unlike the twin-hulled S.55 flying boat, the S.64 was a landplane. The S.64 consisted of a large, thick cantilever wing. A fuselage nacelle was blended into the center of the wing. The nacelle protruded below the wing and extended beyond its leading edge, but it was part of the wing’s structure. The pilot and copilot sat side-by-side and were provided with a rest area for long-distance flights. The wing and fuselage nacelle were made of wood and skinned with plywood. The wing housed 27 fuel tanks that combined to accommodate 1,717 gallons (6,500 L) of fuel.

Two frame booms made of duralumin extended behind the wing and supported the S.64’s slab horizontal stabilizer. Attached to the center of the horizontal stabilizer was the vertical stabilizer and rudder. Large control surfaces were attached to the trailing edge of both the horizontal and vertical stabilizers. Reportedly, the incidence of the horizontal and vertical stabilizers could be adjusted to trim the aircraft. The fixed main gear was faired and was suspended via struts under the wing. A tail skid was attached to the end of each boom.

savoia-marchetti s64 ferrarin del prete

Arturo Ferrarin, Carlo Del Prete, and the S.64.

A single FIAT A.22T V-12 engine was supported on struts above the wing. The FIAT A.22T was liquid-cooled and had a 5.3 in (135 mm) bore and 6.3 in (160 mm) stroke. The engine displaced 1,677 cu in (27.5 L) and produced 550 hp (410 kW). With the exception of its valve covers, the engine was encased in a streamlined cowl. At the very front of the cowl was a large oil tank for the engine. The pusher engine turned a two-blade wooden propeller with a streamlined, pointed spinner. Coolant from the engine traveled down the supporting struts into a radiator under the rear of the wing. The semi-retractable radiator could be extended below the wing for increased airflow.

The S.64 had a 70.5 ft (21.5 m) wingspan and was 34.1 ft (10.4 m) long. The aircraft had an empty weight of 5,291 lb (2,400 kg). Its useful load was 10,141 lb (4,600 kg), resulting in a maximum weight of 15,432 lb (7,000 kg)—nearly three times its empty weight. Its top speed was 146 mph (235 km/h), and cruise speed was around 100 mph (160 km/h). Takeoff speed with a heavy load was 93 mph (150 km/h). The S.64’s maximum range was estimated as 7,146 miles (11,500 km).

savoia-marchetti s64 Brazil

Brazilians assist the S.64 after it landed on the beach near Touros.

The first S.64, registered as I-SAAV, was first flown on 3 April 1928 at Cameri airfield in northern Italy by Alessandro Passeleva. The aircraft was then flown by Arturo Ferrarin and Carlo Del Prete, two men who would become very experienced in the S.64. Initial flight tests revealed the aircraft had a high takeoff speed that necessitated a smooth runway. On 18 April, Ferrarin flew the S.64 to Aeroporto Alfredo Barbieri in Montecelio, near Rome, where a special 4,265 ft (1,300 m) runway had been prepared. The beginning of the runway was paved and had a 6.5 percent grade to aid the aircraft’s initial acceleration. The rest of the runway had a 0.56 percent grade and was unpaved. Flight testing continued with progressively larger fuel loads, and a larger 9.8 ft (3.0 m) diameter propeller was fitted

On 31 May, Ferrarin and Del Prete took off with 921 gallons (3,486 L) of fuel in an attempt to set a new closed circuit distance record. The circuit was from Casale dei Prati in Montecelio to the tower at Torre Flavia (west to the coast) then south to the lighthouse at Anzio (by the coast) and back to Montecelio. After 58 hours and 34 minutes, Ferrarin and Del Prete landed at Montecelio on 2 June after traveling 4,763.82 miles (7,666.62 km) at an average speed of 86.48 mph (139.18 km/h). The S.64, with Ferrarin and Del Prete, had set new records for endurance, distance, and speed over a 5,000 km course. The S.64 beat the endurance record set by Americans Edward Stinson and George Haldeman, who flew for 53 hours and 35 minutes in a Stinson Detroiter aircraft in late March 1928.

savoia-marchetti s64 bis

A side view of the S.64 bis illustrating the duralumin booms that attached the tail to the rest of the aircraft.

The S.64 was then prepared for its next record flight—a straight-line flight of over 5,800 miles (9,300 km) from Montecelio to Rio de Janerio, Brazil. However, that plan was changed on account of high temperatures in Montecelio that would have necessitated a longer takeoff run. The runway at Montecelio had already been extended by 1,312 ft (400 m); its length was now 5,577 ft (1,700 m), but that would not be enough. The new destination was Bahia (now Salvador), Brazil, some 5,280 miles (8,500 km) away. The shorter flight allowed the fuel load to be reduced by 370 lb (168 kg), from 8,377 lb (3,800 kg) to 8,007 lb (3,632 kg).

On the evening of 3 July, Ferrarin and Del Prete departed Montecelio and headed southwest. The S.64 traveled toward Gibraltar and then headed down the coast of Africa and out across the Atlantic. On the afternoon of 5 July, Ferrarin and Del Prete crossed the Brazilian coastline, only to discover thick fog below. After searching in vain for a landing strip, they went back to the coast and set the S.64 down on the beach near Touros, Brazil. Landing in the sand damaged the S.64’s landing gear and fuselage. Not accounting for the distance flown looking for a landing strip, the S.64 set a new straight-line distance record of 4,466.58 miles (7,188.26 km). The flight was 49 hours and 15 minutes. Later, the S.64 was taken by ship to Rio de Janerio and donated to Brazil. (Unfortunately, Del Prete died in Brazil on 16 August 1928 from injuries suffered in the crash of another aircraft. A monument honoring Del Prete and the S.64’s flight was built in the Praça Carlo Del Prete in Laranjeiras, Rio – Rio de Janeiro, Brazil.)

savoia-marchetti s64 bis flight

The S.64 bis in flight showing the similar engine, wing, and boom configuration to the S.55.

Later in July after the S.64’s flight to Brazil, the Germans took the S.64’s endurance record with Johann Risztics and Wilhelm Zimmermann flying for 65 hours and 25 minutes in a Junkers W 33. Italy wanted the record back, and so the second S.64 was built. Finished in early 1929, the aircraft was designated S.64 bis to indicate changes made from the first S.64. The S.64 bis had a longer windscreen and a variable-pitch metal propeller.

Umberto Maddalena and Fausto Cecconi were selected to fly the S.64 bis, registered as I-SAAT. While flight testing was delayed in late 1929 because of bad weather, the French pilots Dieudonné Costes and Paul Codos took the S.64’s distance record. Flying in a Breguet 19 in mid-December, Costes and Codos traveled 4,989.26 miles (8029.44 km). Now the challenge was to set new endurance and distance records, and the S.64 bis would not disappoint.

savoia-marchetti s64 bis landing

The Savoia-Marchetti S.64 bis coming in for a landing.

On 30 May 1930, Maddalena and Cecconi took off from Montecelio in the S.64 bis and followed the same closed circuit course that the S.64 had traveled. Landing on 2 June (the second anniversary of Ferrarin and Del Prete’s flight), Maddalena and Cecconi and the S.64 bis were the new endurance and distance record holders. Their 67 hour, 13 minute, and 55 second flight had covered 5,088.28 miles (8,188.80 km).

Unfortunately the S.64 bis would set no additional records. On 19 March 1931, Maddalena and Cecconi and radio operator Giuseppe Da Monte embarked on a flight from Cinisello (near Milan) to Montecelio. About halfway into their flight, near Pisa, a failure occurred and the S.64 bis crashed into the sea off Calambrone. It is believed that the FIAT’s crankshaft broke, allowing the propeller to cut into the wing and fuselage nacelle of the S.64 bis. However, a definitive cause was never found. Tragically, Maddalena, Cecconi, and Da Monte were killed in the crash.

Carlo Del Prete memorial

The Carlo Del Prete memorial in Rio de Janeiro, Brazil. A sculpture of the S.64 flies above a stature of Carlo Del Prete as he stands before a plaque detailing the record flight. (Silvio Cezar Scremin image)

Sources:
Aeroplani S.I.A.I. 1915-1930 by Giorgio Bignozzi and Roberto Gentilli (1982)
SIAI Pagine Di Storia (1976)
Italian Civil and Military Aircraft 1930-45 by Jonathan W. Thompson (1963)
Jane’s All the World’s Aircraft 1931 by C. G. Grey (1931)
“The Rome—Brazil Non-Stop Flight” Flight (12 July 1929)
“Well-known Italian Pilots Killed” Flight (27 March 1931)
“The Accident to the S.64” Flight (3 April 1931)
http://archive.is/cNtFo
http://en.wikipedia.org/wiki/Savoia-Marchetti_S.64

Alcor Duo-6 Lockheed

Alcor Duo-4, Duo-6, and C-6-1 Transports

By William Pearce

In 1929, the Lockheed Aircraft Corporation was bought by the Detroit Aircraft Corporation. Lockheed’s founder, Allan H. Loughead (phonetically pronounced Lockheed) was unhappy with the acquisition and had voted against it. Allan left and formed a new company in 1930 with his brother Malcolm. The pair had worked together in aviation before pursuing separate interests in the 1920s. The new company was known as the Lockheed Brothers Aircraft Corporation.

Alcor Duo-4 front

The Duo-4 with “Olympic” written on the nose. Note the cooling slits for the Menasco Pirate engines.

Their first aircraft was the Olympic Duo-4, and its fuselage was similar to the Lockheed Vega 5. In place of the Vega’s single radial engine were two Menasco C4 Pirate engines. These in-line, four-cylinder engines were air-cooled and produced 125 hp (92 kW). The engines were positioned in the nose of the Duo-4 so that the tips of the propellers cleared each other by about 3 in (76 mm). The engines were laid on their sides so that their heads were close together and the crankshafts were farthest apart and canted out at a slight angle. The Duo-4’s engine arrangement had less air resistance than a normal twin-engine plane. In addition, when one engine was shut down, the Duo-4 behaved much like a single-engine aircraft.

The four to six passenger Duo-4 was a high-wing cantilever monoplane. The monocoque fuselage had a wooden structure and was covered with a plywood skin that was molded under pressure. The wings also had a wooden structure and were covered with plywood. The aircraft (registered as NX962Y) was first flown by Frank Clarke in 1930. In March 1931, the Duo-4 was damaged when a sudden gust of wind caused it to nose-over and then collide with a vehicle during a landing at Muroc (now Edwards Air Force Base), California. Unfortunately, this incident caused investors to back away from the Lockheed Brothers Aircraft Corporation, and funds were not available to quickly repair the Duo-4.

Alcor Duo-4 Pancho Barnes

The Olympic Duo-4 at Muroc Dry Lake with Florence “Pancho” Barnes. Note that “Olympic” no longer appears on the nose and the propeller tip clearance.

Over the next few years, the Duo-4 was slowly repaired and modified. The four-cylinder Pirate engines were replaced by six-cylinder Menasco B6S Buccaneer engines. The supercharged, 230 hp (171 kW) Buccaneers were in-line, air-cooled engines and turned 7 ft 6 in metal propellers. After the modifications, the aircraft was renamed the Duo-6 (some sources refer to it as the Loughead Alcor). It flew again in early 1934.

Allan Loughead officially changed his name to Allan Lockheed in February 1934. Also in 1934, the Lockheed Brothers Aircraft Corporation went out of business, but Allan continued with the Duo-6. In May 1934, one propeller was removed to demonstrate the Duo-6’s single engine performance. At Mines Field (now Los Angeles International Airport), the Duo-6 took off in 1,200 ft (366 m) and attained 130 mph (209 km/h) on just one engine. Reportedly, with one engine shut down, the aircraft handled with little yaw, much like a single-engine plane. In May, Allan flew the Duo-6 back east to demonstrate it to the Navy and Army. However, nothing came from this exposure.

Alcor Duo-6 Lockheed

The Duo-6 on its trip back east with Allan Lockheed in front. Note that “Alcor” is written on the tail and the changes to the engine cowling from the Duo-4 image above.

In October 1934, the United States placed operating restrictions on single-engine transports carrying passengers. This regulation marked a permanent shift to multi-engine transports for passenger service. Presumably, the twin-engine Duo would have done well under the new regulations with its ability to perform like a conventional single-engine aircraft in the event of one engine being shut down. Unfortunately, the Duo-6 crashed in late 1935 and was not repaired.

The Duo-4 and Duo-6 had a 42 ft (12.80 m) wingspan and were 28 ft 6 in (8.69 m) in length. The Duo-4 had an empty weight of 2,265 lb (1,027 kg). The aircraft had a max speed of 140 mph (225 km/h) and a landing speed of 47 mph (76 km/h). The Duo-6 had an empty weight of 2,885 lb (1,309 kg) and a gross weight of 5,090 lb (2,309 kg). The aircraft had a max speed of 183 mph (295 km/h), a cruise speed of 157 mph (253 km/h), and a landing speed of 57 mph (92 km/h). The service ceiling was 18,500 ft (5,639 m) and its range was 660 mi (1,062 km). The single engine performance of the Duo-6 was a max speed of 125 mph (201 km/h), a cruise speed of 100 mph (161 km/h), and a ceiling of 6,400 ft (1,951 m).

Alcor C-6-1 top

This unique top view of the C-6-1 doing an engine run shows how the engine nacelles were blended into the nose and wings.

In February 1937, Allan started a new aviation company: the Alcor Aircraft Corporation. The “Alcor” came from Allan Lockheed Corporation. Alcor’s first official aircraft (the Duo-6 had been built before the company was formed) was the C-6-1 Junior Transport. It was designed to carry six to eight passengers. The C-6-1 used the engine installation of the Duo but with improved C6S-4 Super Buccaneer engines that produced 275 hp (205 kW) at 2,400 rpm for takeoff. Each engine was canted out 4 degrees and the propellers cleared each other by 12 in (0.3 m).

The aircraft had a low-wing, and the main gear retracted back into the wing with the wheels turning 90 degrees to lay flat. The wings and fuselage had a structure made mostly of wood. However, there were some components in high-stress areas that were made of metal. The fuselage had a circular section and was made up of laminated spruce framework with a two-piece plywood skin that was molded under pressure. The engines were closely cowled and faired into the nose and wing. The C-6-1 was a streamlined aircraft that was very efficient and had excellent flight characteristics.

Alcor C-6-1 side

Side view of the Alcor C-6-1 Junior Transport complete with spinners.

The Junior Transport had a wingspan of 49 ft (14.94 m) and a length of 31 ft 8 in (9.65 m). The aircraft had an empty weight of 4,141 lb (1,878 kg) and a gross weight of 6,200 lb (2,812 kg). The aircraft had a max speed of 211 mph (340 km/h) at 5,500 ft (1,676 m) and a cruise speed of 190 mph (306 km/h) at 5,500 ft (1,676 m) and 200 mph (322 km/h) at 10,000 ft (3,048 m). The service ceiling was 24,000 ft (7,315 m) and its range was 835 mi (1,344 km). On one engine, the C-6-1 had a top speed of 147 mph (237 km/h), could cruise at 129 mph (208 km/h), and had a ceiling of 12,600 ft (3,840 m).

The C-6-1 (registered as NX15544) was first flown on 6 March 1938. On a test flight over San Francisco Bay on 27 June 1938, the C-6-1 went out of control during a high-speed dive. The dive test was instigated by the pilot and not part of the flight schedule. Unable to regain control, the pilot and observer bailed out, leaving the sleek C-6-1 to crash into the bay. The aircraft was insured, but the funds were only sufficient to pay off Alcor’s debts. With no capitol, Allan closed out Alcor. Allan continued to be involved in aviation for the rest of his life, but he did not build any further aircraft of his own design.

Even though the Duo-4 and Duo-6 were built under Lockheed Brothers Aircraft Corporation name, they are often referred to as the Alcor Duo-4 and Alcor Duo-6. In addition, the Alcor C-6-1 is often incorrectly referred to as the Lockheed Alcor.

Alcor C-6-1 flight

Alcor C-6-1 on a fight over San Francisco Bay. The San Francisco Bay Toll-Bridge (now San Mateo–Hayward Bridge) can be seen in the background. Note the absence of spinners on the otherwise sleek aircraft.

Sources:
Jane’s All the World’s Aircraft 1932 by C.G. Grey
Jane’s All the World’s Aircraft 1934 by C.G. Grey
Jane’s All the World’s Aircraft 1938 by C.G. Grey and Leonard Bridgman
Lockheed Aircraft since 1913 by Rene J. Francillon (1982/1987)
– “Commercial Aviation: An American Feeder-Line Machine,” Flight 6 July 1934
– “A ‘Flat’ Engined Transport,” Flight 12 May 1938
http://1000aircraftphotos.com/Contributions/HornDavid/9336.htm
http://www.aerofiles.com/_al.html
Brief Allan Lockheed 1910-1942 Autobiography
http://en.wikipedia.org/wiki/Allan_Loughead

Navy-Wright NW-1 Pulitzer

Navy-Wright NW-1 and NW-2 Racers

By William Pearce

Wright Aeronautical designed the T-2 engine in 1921 as a possible replacement for the Liberty V-12 engine and with the interest of the United States Navy. Like the Liberty, the Wight T-2 was a liquid-cooled V-12 engine. It also shared the same engine mount locations as the Liberty so that a T-2 could be installed in place of a Liberty. In the summer of 1922, the Navy saw an opportunity to test the 600 hp (447 kW), 1,948 cu in (31.9 L) T-2 engine and also create an air racer to compete in the upcoming Pulitzer Air Race.

Navy-Wright NW-1 Pulitzer

The Navy-Wright NW-1 (A-6543) with race number 9 at Selfridge Field, Michigan for the 1923 Pulitzer Race. Note that the engine cowling covers the engine cylinder banks. The image illustrates the limited ground clearance of the wheel fairings.

Commander Jerome C. Hunsaker, head of the Navy Bureau of Aeronautics Design Section, designed the T-2-powered racer known as the Navy-Wright NW-1. Two examples were ordered (A-6543 and A-6544), and Wright built the aircraft at Long Island City, New York in a plant rented from the Chance Vought Company. The aircraft was constructed under a fair degree of secrecy, with few details being leaked to the press. Because of the lack of information, the press dubbed the aircraft the Mystery Racer.

The NW-1 was a sesquiplane with the large upper wing situated about mid-height on the fuselage and the much smaller, lower wing in line with the main gear. The main gear was covered with close fitting fairings with little ground clearance. Two Lamblin radiators for engine cooling were located under the streamlined fuselage and above the main gear. The fuselage had a steel tube frame and was metal-covered in front of the cockpit, the rest of the fuselage was fabric-covered. The upper wing was plywood-covered back to the rear spar. The rest of the wing, including the ailerons, was fabric-covered. The lower wing was entirely plywood-covered. The NW-1 was a large racer with a wingspan of 30 ft 6 in (9.3 m), a length of 24 ft (7.3 m), and a height of 11 ft (3.4 m). The aircraft weighed 2,480 lb (1,125 kg) empty and 3,000 lb (1,361 kg) gross. The Wright T-2 engine turned a 9 ft (2.74 m), two-blade, wooden propeller.

Navy-Wright NW-1 Pulitzer rear

This rear view of the NW-1 clearly shows the difference in span of the sesquiplane’s wings. Note the Lamblin radiator supported by the gear struts.

The NW-1 was designed and built in three months. This tight schedule combined with engine delays meant only the first aircraft (A-6543) would be completed in time for the Pulitzer Race. Even so, there was no time to test fly the aircraft. Once the Wright T-2 engine (second production engine made) was installed, the NW-1 was crated and shipped to Selfridge Field, Michigan for the Pulitzer Race. Upon arrival, the NW-1 was prepared for its first flight. On 11 October 1922, three days before the Pulitzer Race, Lt. Lawson H. Sanderson took the NW-1 for its first flight. Sanderson was also the pilot selected to fly the NW-1 in the Pulitzer Race. During the 30 minute flight, the aircraft was clocked at 209 mph (336 km/h). Back on the ground, Sanderson reported that the aircraft had good flying characteristics and that there were no issues.

On the day of the Pulitzer Race, 14 October 1922, the crew had to clear a path on the grass field to make sure no irregularities in the ground would interfere with the NW-1’s very low wheel fairings. Sanderson got the aircraft aloft and entered the course. After 150 km (93 mi) of the 250 km (155 mi) race, the NW-1 was in fifth place and averaging 186 mph (299 km/h). However, the oil temperature had risen to the upper limit of the gauge. The short test flight had not revealed that the aircraft’s oil cooler was insufficient. Sanderson found the gauge disconcerting and temporally “fixed” the issue by covering it with his handkerchief. Of course, this did nothing to alter fate.

Navy-Wright A-6544

The second Navy-Wright NW-1 (A-6544). Note that the engine cowling no longer covered the engine cylinder banks and that the wheels are no longer covered by fairings.

A few minutes later, while over Lake St. Clair, Sanderson could smell the burning oil of the overheating engine and saw smoke trailing behind his racer. He pulled off the course and headed for the closest landfall. As he approached Gaulker Point, he saw the shore crowded with spectators. About then, the T-2 engine finally seized, giving Sanderson very few options. He headed for shallow water, and when he made contact with the water’s surface, the NW-1 quickly flipped over. Sanderson was now underwater, in the cockpit, and stuck in mud; he literally had to dig his way out. Remarkably, Sanderson emerged unharmed, but the NW-1 was destroyed.

Back in Long Island City, the second NW-1 (A-6544) was completed on 22 December 1922. This aircraft differed slightly from the earlier version. It had a modified engine cowling to aid cooling, and the wheel fairings were omitted. Because of the modifications, some sources say that the aircraft’s designation was changed to NW-2 at this time, but most others continued to refer to the aircraft as the NW-1. Obviously confident in the aircraft, Sanderson made the first flight, followed by a number of others, at Mitchel Field, New York. He reported that the oil cooling issue had improved but would still be a problem with warmer weather. He recorded a speed of 186 mph (299 km/h) with the engine at only 1,700 rpm.

Navy-Wright NW-2 rear

NW-2 (A-6544) after conversion to a seaplane with two full-span wings. Note the two-blade propeller, the wing radiators, and ventral fin.

Sometime after January 1923, A-6544 was taken to Wright’s factory in Paterson, New Jersey. Here, the aircraft underwent a major conversion to a seaplane and unquestionably became NW-2. The plan was to use the NW-2 in the Schneider Trophy Race held at Cowes, Isle of Wight, United Kingdom in September.

Both of the original wings were removed and two full-span wings were installed, converting the aircraft into a proper biplane. Two floats replaced the landing gear, and surface wing radiators replaced the Lamblins. The aircraft’s tail and rudder were enlarged and a ventral extension was added. When the NW-2 emerged in July 1923, it was the most powerful seaplane in the world. The NW-2 had a wingspan of 28 ft (8.5 m), a length of 28 ft 4 in (8.6 m), and a height of 11 ft 7 in (3.5 m). The aircraft weighed 3,565 lb (1,617 kg) empty and 4,447 lb (2,017 kg) gross.

Lt. Adolphus W. Gorton chose to fly the NW-2 for the Schneider Race and was also the only one to fly the aircraft during testing. The NW-2 was shipped to the Naval Aircraft Factory on the Delaware River near Philadelphia, Pennsylvania for testing. The first flight following the conversion occurred on 23 July 1923. Gorton reported that the aircraft was tail-heavy and created excessive spray while on the water. At the time, the NW-2 had a large, 8 ft 6 in (2.59 m) diameter wooden propeller. Adjustments to the NW-2 were made, including replacing the two-blade propeller with a metal, three-blade, 7 ft 6 in (2.29 m) diameter unit.

Navy-Wright NW-2

The NW-2 with race number 5 at the Isle of Wight and ready for the Schneider race. Note the three-blade propeller.

Test flights continued, and on 9 August 1923, Gorton was clocked at over 180.8 mph (291 km/h). On 18 August, Gorton, the NW-2, and the rest of the US Schneider team left for England on the SS Leviathan. After talking to the pilots of the Curtiss CR-3 racers also competing in the Schneider Trophy Race, Gorton realized that the NW-2 did not have the speed needed to win. As a result, the team decided to run the Wright T-2 engine at 2,250 rpm.

Gorton took the NW-2 up for a test flight and was clocked at an unofficial 204 mph (328 km/h). Everything had gone well on the flight. On 24 September 1923, Gorton took the NW-2 up again to get more familiar with the Schneider course. After 20 minutes of flight, while at a high-speed and a low-level, the Wright T-2 engine exploded, with parts flying in all directions. The NW-2 crashed into the waters of the Solent, flipped over and tossed Gorton out in the process. Unharmed, Gorton clung to pieces of wreckage until a boat rescued him. Like the NW-1, the NW-2 was completely destroyed after crashing into water. The Curtiss CR-3 racers went on to finish first and second in the Schneider Trophy Race.

Navy-Wright NW-2 tow

The Navy-Wright NW-2 being towed before a test flight. Lt. Adolphus W. Gorton can be seen in the middle of the boat.

Sources:
The Speed Seekers by Thomas G. Foxworth (1975/1989)
The Pulitzer Air Races by Michael Gough (2013)
Schneider Trophy Seaplanes and Flying Boats by Ralph Pegram (2012)
The Air Racers by Charles A. Mendenhall (1971/1994)
http://woodenpropeller.com/forumvB/showthread.php?t=3235&highlight=hartzell

Martin-Baker MB2 final tail

Martin-Baker MB2 Fighter

By William Pearce

In 1934, James Martin and Captain Valentine Baker formed the Martin-Baker Aircraft Company in Denham, United Kingdom. Designed by Martin, their first aircraft was the MB1—a low-wing touring aircraft with a two-place enclosed cockpit. First flown by Capt. Baker in April 1935, the MB1’s airframe was comprised of a steel tube structure, and the wings could be folded back for transport or storage. However, with the political situation in Europe deteriorating, and with Britain in search of new fighter aircraft, Martin-Baker turned its attention to designing a new fighter: the MB2.

Martin-Baker MB2 final tail

The Martin-Baker MB2 eight-gun fighter with its final tail configuration.

The MB2 started as a private venture around 1935 and closely followed Air Ministry Specification F.5/34 issued in 1934 for an eight-gun, 275 mph fighter aircraft. The MB2 was to be an easily produced and low cost fighter. Construction on the MB2 began in March 1936 and utilized the same steel tube construction techniques employed on the MB1. The wings and forward fuselage were covered by duralumin, and the rear fuselage and control surfaces were fabric covered. For simplicity and lightness, the MB2 had fixed undercarriage housed in streamlined fairings; the left fairing also incorporated an engine oil cooler. A pneumatic crash pylon would extend above the canopy to protect the pilot in the event of a nose-over during takeoff or landing.

Martin-Baker MB2 pylon

The MB2 with the crash pylon extended above the cockpit canopy. Note that the canopy provided a 360 degree view.

From the start, Martin had wanted a Rolls-Royce Merlin engine for the MB2, but none were available to the Martin-Baker Company. Napier was willing to loan Martin-Baker a Dagger IIIM engine, and the MB2 was designed around that engine. The Napier Dagger was an air-cooled, 24-cylinder, vertical H engine. With a 3.8125 in (96.8 mm) bore and a 3.75 in (95.25 mm) stroke, the Dagger displaced 1,027 cu in (16.8 L). The moderately supercharged Dagger IIIM produced around 805 hp (600 kW) at 4,000 rpm for takeoff and drove a 10.5 ft (3.2 m), fixed-pitch, two-blade, wooden propeller.

Martin-Baker MB2 marked as M-B-1

An early photo of the Martin-Baker MB2 when marked as M-B-1, with Capt. Baker at the controls. Note the exhaust manifold and how it differs from the other images.

The MB2 was designed with ease of maintenance in mind. All major components were easily accessible. The Dagger engine could be changed out faster than any other engine on any fighter then in service. Two men could remove the MB2’s armament, eight Browning .303 (7.7 mm) machine guns, in under five minutes (compared to 60 minutes for the Hurricane and 70 minutes for the Spitfire). Two men could reload the MB2, 300 rounds per gun, in 15 minutes (compared to 16 minutes for the Hurricane and 60 minutes for the Spitfire). The wings just outside of the gear could be removed in minutes to allow the aircraft to be easily transported or stored. The MB2 had a span of 34 ft (10.4 m), a length of 34 ft 9 in (10.6 m), and weighed 5,537 lb (2,512 kg). At 9,250 ft (2,820 m), the aircraft had a top speed of 305 mph (491 km/h), although some sources say 320 mph (515 km/h). The MB2’s ceiling was 29,000 ft (8,840 m).

Baker made the first flight in the MB2 on 3 August 1938. As first flown, the MB2 did not have any vertical tail. It was thought that the large main gear fairings and flat-sided fuselage would provide directional stability. The rear of the MB2’s fuselage tapered back to a vertical wedge that incorporated the aircraft’s rudder. Directional stability proved insufficient, and a small vertical tail stub was provided above the horizontal stabilizer. A conventional tail was later added to the MB2 after flight trials at Martlesham Heath in late 1938 indicated further improvement in directional stability were needed.

Martin-Baker MB2 with short tail

The MB2 with the revised small stub tail to provided better directional control over the original design having no tail. However, this tail configuration was still insufficient.

Early on, the MB2 carried “M-B-1” on the side of its fuselage for reasons that have not been made clear. While at Martlesham Heath, the MB2 was loved by ground crews for its ease of maintenance and serviceability. However, pilots found it lacking directional control, with insufficient rudder authority and heavy aileron control. Because of the control difficulties, it would not have made a good gun platform.

After the tail was modified to address the directional instability, the aircraft was re-evaluated at Martlesham Heath in late 1939. The new rudder was found to be satisfactory and effective, but the other flight controls still needed improvement. Designs were also made to fit the MB2 with fully retractable gear and change out the machine guns for cannons. But these changes were not pursued.

Martin-Baker MB2 flight

The Martin-Baker MB2 in flight with the final tail configuration. Note the opening for the oil cooler on the left main gear fairing and the exhaust ports on the cowling.

The Air Ministry purchased the MB2 in July 1939, but it was clear that there would be no further modifications or any chance of a production contract. While the MB2’s shortcomings could have been addressed, it would not have changed the fact that the aircraft was developed for a fighter specification over five years old. However, Martin-Baker was tasked to take what they had learned from the MB2 and develop a new Napier Sabre-powered fighter, which would become the MB3. The sole MB2 was scrapped in 1944. Designed and built by a small company with fewer than 40 employees, the MB2 exemplified simple and inexpensive construction techniques employed on an aircraft that was designed for ease of serviceability and whose performance could match fighter aircraft then in service.

Martin-Baker MB2

From left to right, Captain Valentine Baker, James Martin, and Francis Francis, who provided funding for the Martin-Baker Aircraft Company, stand next to the MB2.

Sources:
– “Martin-Baker Fighters,” by Bill Gunston, Wings of Fame Volume 9 (1997)
The British Fighter Since 1912 by Francis K. Mason (1992)
Interceptor Fighters for the Royal Air Force by Michael J.F. Bowyer (1984)
British Piston Aero-Engines and Their Aircraft by Alec Lumsden (1994/2003)
http://www.martin-baker.com/about/mb1-mb5

Piaggio P.23M front

Piaggio P.23M Transport Prototype

By William Pearce

The Piaggio P.23M was a prototype commercial transport aircraft intended for northern transatlantic flights. If flight testing was successful, the possibility existed to develop the unique aircraft for regular passenger service. Designed in 1934 by Giovanni Pegna, the P.23M was partly inspired by the Piaggio P.16 bomber prototype (also designed by Pegna). Two examples of the P.23M were ordered on 31 May 1934 and given the serial numbers MM 263 and MM 264.

Piaggio P.23M front

The elegant Piaggio P.23M transport prototype.Note the intakes above and below the spinner for funneling cooling air into the radiators for the tandem engines .

The P.23M was a four-engine, all-metal aircraft with twin tail fins and rudders. The underside of the aerodynamically clean fuselage had a keel, much like a flying boat, and was watertight. While the aircraft could not operate from the water, the keel fuselage design was incorporated to facilitate emergency water landings. This feature was reflected in the P.23M’s name, the “M” representing Marino (Marine) .

The P.23M’s wing was a semi-cantilever, inverted-gull design (similar to the P.16’s) and was supported by three struts on each side. Each wing carried a long nacelle that housed two Isotta-Fraschini Asso XI R engines mounted in tandem. The foreword engine drove a tractor propeller, and the rear engine drove a pusher propeller. Each nacelle also housed the radiators for the engine pair and the retractable main landing gear.

Piaggio P.23M side

The boat-like keel at the front of the P.23M’s fuselage can be seen fading toward the rear of the aircraft in this side view.

The Asso XI R engine was a 12-cylinder Vee with a 5.75 in (146 mm) bore and a 6.30 in (160 mm) stroke. Total displacement was 1,962 cu in (32.1 L), and the engine produced 900 hp (671 kW). The Piaggio P.23M had a wingspan of 88 ft 7 in (27.0 m) and was 54 ft 6 in (16.61 m) long. The aircraft’s empty weight was 16,290 lb (7,387 kg), and maximum weight was 40,651 lb (18,439 kg), resulting in an impressive useful load of 24,365 lb (11,052 kg). Calculated speeds were 249 mph (400 km/h) maximum and 186 mph (300 km/h) cruise. Cruising range was estimated at 3,167 miles (5,100 km). Climbing calculations indicated the P.23M could reach 13,125 ft (4,000 m) in 14 minutes.

The Piaggio P.23M first took to the air on 25 October 1935 at Villanova d’Albenga, Italy. Tragically, something during the flight went horribly wrong. The aircraft crashed, and both test pilots, Ciacci and Risso, were killed.

Piaggio P.23M rear

The P.23M’s inverted gull wing and twin tails can be seen in this rear view, along with the aerodynamically clean fuselage.

While the exact cause of the crash is not known, it could have had something to do with the aerodynamic effect of the tandem engines and propeller pulses on the twin tails. The design for the second P.23M (MM 264), which had not been built, was converted to a trimotor configuration and redesignated P.23T. As a further development of the P.23M, the Piaggio P.50 I heavy bomber retained the tandem engines in each nacelle, but the twin tails were replaced with a single tail. Subsequently, the P.50 II had a conventional layout for its four engines—each in a separate nacelle.

Ultimately, the P.23T trimotor transport proposal was abandoned, and an entirely new aircraft was designed and constructed as the P.23R. Despite the similar designation, the P.23R had nearly nothing in common with the P.23M. Neither the P.23 nor P.50 series of aircraft proved successful. However, they did provide much experience to facilitate development of the Piaggio P.108 heavy bomber of World War II.

Piaggio P.23M front 2

Another front view of the Piaggio P.23M. Note the right wing’s support struts and the missing cover on the left main gear.

Sources:
Italian Civil and Military Aircraft 1930-1945 by Jonathan W. Thompson (1963)
http://www.giemmesesto.org/Documentazione/Aerei/PIAGGIO_P-23.html
http://www.secretprojects.co.uk/forum/index.php?topic=15099.0
http://en.wikipedia.org/wiki/Piaggio_P.23

Heinkel He 119 V4 front

Heinkel He 119

By William Pearce

In the 1930s, brothers Siegfried and Walter Günter were pushing the limits of aerodynamics as they designed aircraft for Heinkel Flugzeugwerke in Germany. Perhaps the ultimate expression of their aerodynamic beliefs was the Heinkel He 119. The Günter brothers and Ernest Heinkel envisioned the He 119 as an unarmed, high-speed reconnaissance aircraft or light bomber.

Heinkel He119 V1 side

Heinkel He 119 V1 prototype with the hastily installed radiator to augment the evaporate cooling system.

Work on the He 119 began in the summer of 1936 as a private venture funded by Heinkel Flugzeugwerke. The aircraft appeared to have a fairly standard layout as an all metal, low-wing monoplane with retractable gear. However, the very streamlined fuselage hid the He 119’s unorthodox power arrangement. To achieve the low-drag necessary for high-speed operations, the engine was buried in the fuselage, just behind the cockpit and above the wings. An enclosed drive shaft extended forward from the engine, through the cockpit, between the pilot and co-pilot, and to the front of the aircraft where it drove a 14 ft 1 in (4.30 m), metal, variable-pitch, four-blade propeller.

No engine produced the power needed for the He 119, so two Daimler-Benz DB 601 engines were placed side-by-side and coupled together through a common gear reduction. The DB 601 was a liquid-cooled, 12-cylinder, 60 degree, inverted Vee engine with a 5.91 in (150 mm) bore and 6.30 in (160 mm) stroke. When coupled, the 24-cylinder engine was known as the DB 606; it displaced 4,141 cu in (67.8 L) and produced 2,350 hp (1,752 kW). The inner banks of the DB 606 were pointed nearly straight down and exhausted under the aircraft. The side banks’ exhaust was expelled just above the He 119’s wings.

Daimler-Benz DB 606

The Daimler-Benz DB 606 engine was comprised of two DB 601 engines joined to a common gear reduction.

The DB 606 engine in the He 119 was to be cooled exclusively by surface evaporative cooling, where steam from the heated coolant was pumped under the skin of the wing’s center section. Here, the steam would cool and condense back into liquid. The liquid was then pumped back to the engine. However, during testing the system proved to be inadequate, and a radiator was added below the fuselage, just before the wings. The first prototype had a fixed radiator that was rather hastily installed. The subsequent prototypes included an improved radiator that was extended during low-speed operations but was semi-retracted into the fuselage as the aircraft’s speed increased.

The He 119’s cockpit formed the nose of the aircraft. The cockpit was entirely flush with the 48 ft 7 in (14.8 m) fuselage and was extensively glazed with heavily framed windows. The pilot and co-pilot accessed the cockpit by separate sliding roof panels. In the aft fuselage were provisions for a radio operator and a ventral bay for cameras. Another bay for either large cameras or a maximum of 1,200 lb (1,000 kg) of bombs was located in fuselage, just aft of the wing spar.

Heinkel He 119 nose radiator

A good view of the He 119’s glazed cockpit is provided in this image. Most sources state this aircraft is V4, but it possesses the exhaust ports of V1. Note the extended radiator.

The He 119 had a wingspan of 52 ft 6 in (16 m). To provide for proper ground clearance, conventional main landing gear would have been too long to fit in the inverted-gull, semi-elliptical wing. A telescoping strut was devised that would collapse as the gear retracted. This allowed the gear to fit within the wing and also extend to provide the needed ground clearance.

Heinkel kept the He 119 a secret during construction, and the first prototype (V1) flew in June 1937 with Gerhard Nitschke at the controls. Even with the bulk of the added radiator, the aircraft achieved 351 mph (565 km/h), which was faster than fighter aircraft of the day. This speed validated Heinkel and the Günter brothers’ position that the fast bomber did not need to be armed. However, when the aircraft was revealed to German officials, they insisted the aircraft be armed with upper and lower guns operated by separate gunners. German officials did allow the continued experimentation of the aircraft; at this point, the aircraft was officially designated He 119. The addition of the guns lowered the aircraft’s speed, and it appears that only the upper gun was included in other prototypes, housed under a sliding panel.

Heinkel He 119 V2 with windows in the rear fuselage for the radio operator.

Heinkel He 119 V2 with windows in the rear fuselage for the radio operator. Reportedly, this is the last He 119 built with the semi-elliptical wing.

It is at this point that sources disagree on the He 119’s history. One theory is that the second prototype (V2) first flew in September 1937, followed by the fourth prototype (V4) in October 1937. The He 119 V4 set a speed record on 22 November 1937 and was destroyed in a follow-up attempt on 16 December. A total of eight aircraft were built; the seventh (V7) and eighth (V8) were purchased by and subsequently shipped to Japan.

The other theory, supported by German Heinkel expert Dr. Volker Koos, is that the V1 was prepared (which included the installation of a new radiator as used on the subsequent prototypes) for the record flight. The V1 flew the record flight and crashed during the follow-up attempt. The first flight of V2 was in 1938, and V4 first flew in May 1940. Most likely, only four aircraft were built, and V2 and V4 were shipped to Japan.

Side view of the He 119 V3. The updated wing used on the V3 and all further He 119 aircraft can be seen as well as tail modifications to increase the seaplanes stability.

Side view of the He 119 V3. The updated wing used on the V3 and all further He 119 aircraft can be seen as well as tail modifications to increase the seaplane’s stability.

All sources agree that the He 119 carrying the registration D-AUTE made the record flights. The third prototype (V3) was first flown after V4 because V3 was built as a seaplane. All prototypes from V3 on were built with a new wing that had a straight leading edge and a slightly reduced span of 52 ft 2 in (15.9 m).

After careful examination of various photos, it appears that the He 119 registered at D-AUTE had the semi-elliptical wing as used on the first two prototypes. It also appears that the exhaust ports above the wing on V1 were unique and at an angle, with each port slightly higher (relative to the fuselage) than the port preceding it. All other He 119s had exhaust ports in a straight line relative to the fuselage. D-AUTE appears to have the ports as seen on V1. Based on the information available, it seems more likely that V1 did indeed make the record flights. Sadly, given the secrecy under which the He 119 was built, the propaganda subterfuge surrounding the record flights, and the destruction of German documents during World War II, the exact aircraft identities as well as the number built may never be definitively known.

Heinkel He 119 V3 b

The Heinkel He 119 V3 seaplane taxiing under its own power. This aircraft was to be used on an attempt to set a new 1000 km (621 mi) seaplane record, but such plans were cancelled after the other He 119’s crash.

Regardless of the specific airframe, on 22 November 1937, the He 119 set a world record for flying a payload of 1,000 kg (2,205 lb) over a distance of 1,000 km (621 mi). For propaganda purposes, the He 119 was labeled He 111U and also He 606. Due to weather, the He 119 was forced to fly lower than anticipated which reduced its airspeed. Even though the He 119 set the record at 313.785 mph (504.988 km/h), the speed was seen as a disappointment that did not represent the He 119’s true capabilities. Indeed, the record was broken about two weeks later by an Italian Breda Ba 88.

A follow-up flight to reclaim the record occurred on 16 December 1937.  With over half the distance flown and the He 119 averaging just under 370 mph (595 km/h), the DB 606 engine quit. The pilots, Nitschke and Hans Dieterle, attempted an emergency landing at Travemünde but hit a drainage ditch. The He 119 was destroyed; Nitschke and Dieterle were injured, but they survived. The engine failure was a result of a faulty fuel transfer switch. After the crash, Heinkel was ordered not to attempt any further record flights with the He 119.

Heinkel He 119 V4 front

Many sources identify this aircraft (D-ASKR) as the He 119 V2. Interestingly, the wing root intake for the supercharger and lower lip of the radiator do not match those found on other images of V2. The features do match those found on V3.

Other He 119 prototypes took over the test flights. He 119s with the new wing demonstrated a top speed of around 370 mph (595 km/h) and a range of 1,865 mi (3,000 km). Despite the floats, the He 119 V3 seaplane had a top speed of 354 mph (570 km/h) and a range of 1,510 mi (2,430 km). The V3 aircraft also had a ventral fin added to counteract the destabilizing effects of the floats. Unfortunately, the German authorities did not have any interest in producing the He 119 in any form because of its unorthodox features. Reportedly, some of the remaining aircraft served as test-beds for the DB 606 and DB 610 engines. The remaining He 119s in Germany were scrapped during World War II.

Late in 1938, the He 119 was shown to a Japanese Naval delegation that expressed much interest in the aircraft. In 1940 the Japanese purchased a manufacturing license for the He 119 along with two of the prototype aircraft. These aircraft were delivered via ship to Japan in 1941 (some say 1940). The aircraft were reassembled at Kasumigaura Air Field, and flight tests occurred at Yokosuka Naval Base. During an early test flight, one of the He 119s was badly damaged in a landing accident, and it is believed the other He 119 suffered a similar fate. While it was not put into production, the He 119 did provide the Japanese with inspiration for the Yokosuka (Kugisho) R2Y1 Keiun high-speed reconnaissance aircraft.

Heinkel He 119 V2 with the Japanese Naval delegation.

The Heinkel He 119 with the Japanese Naval delegation. The sliding roof panel for the pilot’s cockpit access can clearly be seen. Note the differences with the wing root intake and lower lip of the radiator compared to the D-ASKR aircraft.

Sources:
– “An Industry of Prototypes – Heinkel He 119”, Wings of Fame, Volume 12 by David Donald (1998)
Warplanes of the Third Reich by William Green (1970/1972)
http://www.whatifmodelers.com/index.php/topic,21627.0/
http://forum.12oclockhigh.net/showthread.php?t=14198