North American Harvard
From the same stable as the P-51D Mustang, the North American Harvard and the New Zealand Warbirds association seem to go hand and hand with most people in this country. Perhaps this is due to the type's high-profile aerobatic display team, the "Roaring Forties", or the number of Harvard's registered with the association but whatever the reason, the comment so often heard when they fly over is "look, it's the Warbirds". To cover, in any detail, every individual variant of the aircraft produced would (and indeed has, in many cases) fill an entire book. It was one of the most widely produced and used training aircraft ever.
The origins of the Harvard can be traced back almost 70 years to 1934 when the US Army Air Corps announced that they were looking for a new training aircraft. In response, North American Aviation developed the NA-16 as a private venture in the hope of securing a contract. This was a cantilever low wing monoplane with a mixture of metal and fabric covering an all-metal construction. It had fixed landing gear, a tandem, two seat open cockpit and power was provided by an un-cowled, nine cylinder 400 hp Wright R-975 Whirlwind radial engine driving a two-blade propeller. On April 1, 1935, test pilot Eddie Allen took the prototype up for its first flight and 21 days later, it was flown at Wright Field, Dayton, Ohio for evaluation by the USAAC. A production order, incorporating a number of changes requested by the USAAC (including an enclosed cockpit) was issued shortly after as the BT-9 (Basic Trainer 9). North American began work on a pre-production model of the BT-9, the NA-18, which incorporated the requested changes. The most noticeable differences between this aircraft and the NA-16 were the enclosed cockpit and the addition of streamlined fairings on the main gear. The original Wright engine was replaced by a 550 hp Pratt and Whitney R-1340-41 Wasp, but this was changed to a 400 hp Wright R-975-5 Whirlwind engine on the production version of the BT-9 (NA-19), the first of which flew on April 15, 1936.
The BT-9 entered USAAC service in 1936 and export orders soon followed. This led to a seemingly confusing system by North American of giving the aircraft a model number and a charge number such as the 550 hp Pratt and Whitney R-1340 powered NA-16-1A (NA-32 - charge number) that was supplied as a pattern aircraft to the Commonwealth Aircraft Corporation or the NA-16-2A (NA-42) and NA-16-2H (NA-20) supplied to Honduras. Apart from some minor alterations (and the more powerful engine for the NA-32), these aircraft were the same as the BT-9. The US Navy also operated the BT-9 as the 500 hp Pratt and Whitney R-1340-6 powered NJ-1 (NA-28).
A year after the BT-9 entered service, the USAAC issued Circular Proposal 37-220 calling for a combat training aircraft that could carry armament and equipment similar to that found in operational aircraft and also duplicate their handling characteristics. This led North American to develop the NA-26 prototype, essentially a BT-9 with retractable landing gear and a 550 hp Pratt and Whitney R-1340-47 Wasp engine driving a Hamilton Standard variable pitch propeller. The wing centre section was widened by 12 inches to allow for the inward folding landing gear without losing any ground clearance and faired housings were installed at the wing roots so the gear could be retracted to lie flush with the underside of the wing. A hydraulic system operated by an engine pump was introduced to operate the landing gear as well as replacing the manual system used to operate the flaps on the BT-9. This was controlled in a rather interesting (for want of a better word) manner by a series of selector valves and a control button. It worked by selecting the required action, landing gear up for example, and then pressing the control button. The hydraulic fluid (which normally flowed freely around the system) was then forced into the selected valve, completing the action. In recognition of the aircraft's intended role as a combat trainer, provision was made for 0.3 in Colt-Browning machine guns to be mounted in the nose cowling and wings as well as on a flexible mount in the rear cockpit.
In March 1937, the NA-26 was test flown by the USAAC at Wright Field and three months later, an initial order was placed for the aircraft as the BC-1 (Basic Combat Trainer 1). Given the company designation NA-36, around 170 BC-1s were eventually built with 30 being converted to BC-1I instrument trainers. The Royal Air Force, who were desperately seeking large numbers of training aircraft, also showed an interest in the BC-1. Unable to source locally produced aircraft in sufficient numbers, they placed an order in June 1938 for 400 unarmed BC-1s, fitted with British instrumentation and radios as well as bucket seats to accommodate seat pack type parachutes. These were given the model number NA-16-1E and the charge number NA-49 but were better known by their British name, the Harvard Mk.I (named after the famous American university). The first Harvard (serial no. N7000) was delivered to the Aeroplane and Armament Experimental Establishment at Martlesham Heath on December 3, 1938 so that a series of tests could be carried out and pilot's notes prepared. The type entered RAF service in January 1939 with No.12 FTS (Flying Training School) at Spittlegate (later renamed RAF Spitalgate due to a typing error) at Grantham, Lincolnshire. The Royal Canadian Air Force, also lacking any modern training aircraft, placed an order for the Harvard Mk.I but on the much more modest scale of two batches of 15. The RCAF Harvards, also designated NA-16-1Es by North American, received the charge number NA-61 and were the same as those delivered to the RAF, apart from the chosen paint scheme and the addition of a long "winter" exhaust following their introduction into service. Canada's cold winters would sometimes make the Harvard difficult to start and it was not uncommon for pilots to over prime the engine when it didn't kick over on the first attempt. This would result in a spectacular burst of flame from the standard, short exhaust when the engine did finally start and in some instances, the fuselage would catch fire as a result. The long exhaust, which ran down the side of the nose to the front of the cockpit safely channelled any wayward flames away from the fuselage and had the added bonus of adding warmth to what was normally a very cold cockpit. The modification was subsequently applied to RAF Harvards as well.
The first RCAF Harvard was accepted on July 20, 1939. By this stage, however, the Harvard Mk.I / BC-1 was already obsolete. Previously, in 1938, North American had designed a prototype light attack version of the BC-1, the NA-44. It was armed with four fixed 0.3 in machine guns and one on a flexible mount in the rear cockpit and bomb racks under the wings and fuselage. In order to provide adequate performance, an 775 hp Wright R-1820-FS2 Cyclone engine driving a three-blade propeller was fitted while structural changes included replacing the steel tube and fabric rear fuselage with a semi-monocoque, all aluminium stressed skin structure and widening the wing centre section by a further 12 inches to accommodate integral fuel tanks. This model was later exported to several countries as the NA-69 and NA-72 as well as being used by the USAAC as the A-27. In addition, the last three BC-1s were built to standard similar to the NA-44. They were powered by a 550 hp Pratt and Whitney R-1340-45 engine and incorporated further improvements such as all metal stressed skin construction used throughout, a more angular vertical stabiliser and redesigned, "squared off" wings. These three aircraft, known as NA-54s by North American, received the USAAC designation BC-2. Following some further airframe modifications and the replacement of the three-blade propeller with a two-blade one, the NA-54 became the NA-55 and was ordered by the USAAC as the BC-1A.
In 1940, the USAAC resurrected the advanced trainer category (which hadn't been used since 1927) and consequently, the last nine BC-1As ordered became AT-6s. Further orders for the AT-6 (now known as the NA-59 by North American) were placed as well as an anglicised version, the Harvard Mk.II (NA-66). A further variant, the NA-64, was also produced for France with 200 being ordered for the Armée de l'Air and 30 for the Aéronavale. Powered by a 450 hp Wright R-975-E3 Whirlwind engine, this model was a mixture of old and new incorporating features from the AT-6 (fuselage construction etc) while retaining the wing plan-form of the BC-1 and the fixed gear of the BT-9. This order was to supplement a previous order for 230 NA-57s, basically a French version of the BT-9, but after only 111 had been delivered, France fell to the Germans. Many of the surviving NA-57s and NA-64s were put to use by the Luftwaffe in either the training role or for type conversion for pilots prior to testing captured American aircraft. The remaining 119 NA-64s were diverted to the RCAF where they became known as the Yale.
By 1940, North American had received large contracts for the Mustang I and B-25 Mitchell. Despite increasing the size of their factory at Mines Field, Inglewood, California (now part of Los Angeles International airport) they were unable to keep up with demand for all three aircraft. Consequently, towards the end of 1940 they began building a new 1,000,000 square foot factory at Hensley Field, a USAAC reserve base 11 miles southwest of Dallas, Texas. Construction of the AT-6 and Harvard series began at the new factory with the aircraft produced there (with the exception of the Harvard) being given the name Texan, a name that was later applied to the aircraft built in Inglewood as well. In addition to the aircraft built in the United States and Australia's CAC Wirraway trainer and (later) Boomerang fighter (developed from the NA-32), production was carried out under licence in a number of other countries.
Between 1938 and 1939, ASJA, the aircraft department of AB Svenska Järnvägsverkstäderna (Swedish Railway Workshops Ltd) produced a version of the NA-16 that was operated by the Svenska Flygvapnet (Swedish Air Force) as the Sk.14. In 1940, ASJA became part of Svenska Aeroplan A.B. (SAAB) and production of the Sk.14 continued followed by the Sk.14A powered by the Italian made 500 hp Piaggio P.VIIRC.35. Japan also produced their own version of the NA-16 after the Imperial Japanese Navy received two aircraft, the NA-37 and NA-47, for evaluation purposes in 1937. Watanabe Tekkosho Kabushiki Kaisha (the Watanabe Iron Works Ltd) began building an armed version of the aircraft in 1941 as the 600 hp Nakajima Kotobuki 2 KAI powered Watanabe K10W1 "Oak". After 26 had been constructed, production was taken over by Nippon Hikoki Kabushiki Kaisha (Japanese Aeroplane Co. Ltd) with a further 150 being built.
Meanwhile, back in the United States, development of the AT-6 line continued with the AT-6A (NA-77). This model was fitted with a 550 hp Pratt and Whitney R-1340-49 engine and the integral fuel tanks were replaced by removable aluminium ones. The US Navy also operated the AT-6A as the SNJ-3 and the tail hook equipped SNJ-3C (the previous NJ-1 had become the SNJ-1 then SNJ-2 in conjunction with developments of the USAAC aircraft). Power for the naval aircraft was provided by either the R-1340-49 or a 600 hp Pratt and Whitney R-1340-AN-1 Wasp. The latter engine also powered the AT-6B (NA-84), a gunnery-training version of the AT-6A armed with up to four 0.3 in Colt-Browning machine guns.
With wartime aircraft production accelerating in 1940 and 1941, concern over shortages of strategic materials, particularly aluminium, led the US government to ask manufacturers to use as much non-strategic material in aircraft not destined for combat roles. As early as 1940, North American had fitted stainless steel wings and tail surfaces to a BC-1A. However, the addition of chromium and nickel (used in the manufacture of stainless steel) to the strategic materials list meant that North American had to abandon this approach. Eventually, they settled on a combination of wood and spot welded, low-alloy steel sheet. This led to the NA-88 with the low-alloy steel being used for parts of the fuselage, the wings, centre section, vertical stabiliser and control surfaces. Mahogany plywood was used for the floorboards, side panels of the forward fuselage and entire rear fuselage. The first NA-88 rolled out of North American's Dallas plant in April 1941 and in June (the same month that the USAAC became the US Army Air Force) an order was placed for 5,370 NA-88s as the AT-6C, 2,400 of which were to go to the US Navy as the SNJ-4. Commonwealth countries also received the NA-88 as the Harvard Mk.IIA. Thankfully, the threatened shortages never eventuated so after 2,970 AT-6Cs had been delivered, construction reverted back to the all-metal and aluminium of the AT-6A. Still given the model number NA-88, by North American, this variant introduced a 24 volt electrical system (with the exception of the Yale, previous models had a 12 volt system) and could be fitted with three 0.3 in Colt-Browning machine guns for gunnery training. It entered service as the AT-6D, SNJ-5 and Harvard Mk.III. The last 800 AT-6Ds were fitted with a clear-view rear canopy and had a strengthened, redesigned rear fuselage and wings permitting sustained aerobatic manoeuvres of up to 6g. They were given the model number NA-121 and subsequent orders were placed for this variant as the AT-6F and SNJ-6.
Outside of the United States, the largest manufacturer of the aircraft was Canada. In August 1938, Noorduyn Aviation Ltd of Montreal, Quebec, had signed a deal with North American to build the NA-16 under licence. At the time, there was no real official interest being shown in producing the aircraft in Canada. However, with that country being chosen as the location of the Empire Air Training Scheme (EATS) the following year, large numbers of Harvards were needed for student pilots who had progressed from basic trainers such as the de Havilland DH82A Tiger Moth. North American was unable to supply the number of aircraft required and the US Government's Neutrality Act, which prohibited the aerial delivery of aircraft to any belligerent nation, made delivery to Canada difficult. Aircraft that had been ordered by Canada had to be flown to Sweetgrass, Montana and then literally pushed across the border by civilians into Coutts, Alberta. This method was far from ideal when it was realised that thousands of aircraft would be needed, so in January 1940, the RCAF placed an initial order with Noorduyn for locally built Harvards. The first Canadian Harvard (RCAF 3034), designated the Harvard Mk.IIB, was completed exactly a year after the contract had been placed and by January 31, 1941, it was ready for delivery. The Canadian aircraft differed little from the AT-6A and, unlike those in RAF service, it had American instruments and radios.
On March 11, 1941, the US government brought in the Lend-Lease act as a way of supplying equipment to allied nations while still remaining neutral. Basically, this worked by having the US Government purchase the goods from the manufacturer and then lend (or lease, at an affordable price) them to the allies. At the end of the war, the US government would repossess the goods; any equipment not returned was either scrapped or paid for. This led to the USAAF placing several orders with Noorduyn totalling 1,800 aircraft on behalf of the RAF. As these aircraft were technically owned by the USAAF, they were given the designation AT-16 to differentiate them from those built in the United States but were known as Harvard Mk.IIBs in the RAF. Six hundred and thirty nine Noorduyn built, RAF Harvards ended up staying in Canada and by the time production of the series ended, 2,810 had been built.
The US Army Air Force became the US Air Force in 1948 and (among other changes) promptly dropped all the AT, BT and PT designations on their training aircraft, replacing them with a T designation. As a result, all the AT-6 series of aircraft still in service became T-6. The following year, work began on upgrading USAF T-6s and US Navy SNJs. They received an improved canopy, a revised cockpit layout, square-tipped propeller blades, F-51 (the USAF designation for the P-51 Mustang) style landing gear and flap-actuating levers, larger fuel capacity and relocated aerial masts. The naval aircraft were also fitted with a steerable tail wheel. This model, the NA-168, entered USAF service as the T-6D and the SNJ-7 and SNJ-7B (armed version) with the navy. Further rebuilds in 1950 added a 600 hp Pratt and Whitney R-1340-AN-1 engine, even more fuel, further cockpit refinements and a steerable tail wheel as standard on all aircraft as well as several other improvements. Still known as the NA-168 by North American, they entered service as the T-6G and, in the case of 59 aircraft used for Forward Air Control and Army Observer roles in the Korean war, the LT-6G. The Canadian Car and Foundry Ltd, who had taken over Noorduyn Aviation in 1946, also produced a variant of the T-6G as the Harvard Mk.4 (the use of Roman numerals having been discontinued by this stage) for the RCAF and T-6J for USAF Mutual Aid Program.
From the NA-16 through to the T-6J, over 21,000 aircraft were built, although exact numbers vary depending on who you speak to or what you read. They saw service with the air forces of over 40 nations, training hundreds of thousands of pilots, navigators and gunners. The South African Air Force was the last user of the Harvard with the SAAF Central Flying School, Langebaanweg, finally retiring them in November 1995. In recognition of their service to that country, a notice was recently published in the South African Government Gazette stating "The National Monuments Commission hereby declares ten Harvard aircraft .... to be cultural treasures on account of the historical and technical importance thereof....." The Royal New Zealand Air Force was also a long time Harvard user operating 202 Mk.II, Mk.IIA, Mk.IIB and Mk.IIIs from 1941 until 1977 when they were finally replaced by the AESL CT/4B Airtrainer.
Following their retirement from various air forces, many surplus T-6s and Harvards were quickly snapped up by private buyers worldwide. Not only did they form the nucleus of many Warbird movements, but they were also put to many other uses ranging from crop spraying to air racing. The famous National Championship Air Races held at Reno, Nevada, even has a special T-6 class race each year. One of the more interesting civilian roles the aircraft undertook was when Twentieth Century fox converted 31 to Japanese "Kate" torpedo bombers, "Val" dive bombers and "Zero" fighters for the movie "Tora, Tora, Tora". The attention to detail was such that a number of Japanese naval personnel who saw the aircraft on location believed them to be the real thing. At present, there are several thousand Texans and Harvards still in existence around the world including around 37 in New Zealand, including at least 16 airworthy examples. Their popularity and availability means that the distinctive howl of Hamilton Standard propeller tips in fine pitch breaking the sound barrier will be heard for some time to come.
Text © 2002 Stuart Russell.
Power plant: One 410kW (550hp) Pratt & Whitney R-1340-AN-1 radial
Wingspan: 12.8m (42ft)
Length: 8.99m (29ft 6in)
Max T-O weight: 2,548kg (5,617lb)
Max speed: 341km/h (212mph)
Range: 1,400km (870miles)