To get a detailed grasp on how it all started for the RAF and the birth of the Mustang, please read our biography on the NA-73X prototype.
The RAF was the first contractor and operator for the aircraft which they dubbed the Mustang in December 1940 (side note: As the Mustangs were initially developed for the RAF, these aircraft used factory numbers and were not called P-51s).
The British Aircraft Purchasing Commission signed its first contract for 320 North American NA-73s on April 24th, 1940. This purchase was placed under the so-called "Cash and Carry" program, as required by the US Neutrality Acts of the 1930s.
Orders placed after March 11th, 1941, were subject to President Roosevelt's proposed Lend-Lease Act.
After the quick development of the prototype NA-73X, NAA started producing the first batch of 320 Mustangs in April of 1941, albeit at a slower rate.
The first Mustang to roll of the production line was NAA construction number 73-3098 and was given the RAF serial number AG345. It rolled of the production line on April 16th and was test flown by Louis Wait on April 23rd at Mines Field.
The first production batch of Mustangs were basically the same aircraft as NA-73, using the same original power plant, the Allison V-1710-39. The only differences with the prototype were:
AG345 was delivered unpainted, but later received RAF style camouflage (dark earth and dark green, with sky gray undersides). Chilton began his work on AG345 with a radiator and scoop test on May 1st and made 17 various test flights with the aircraft by May 23rd.
AG345 was retained for long term testing and squawk fixing at NAA and was struck off charge on December 3rd, 1946.
As stated in the article on NA-73X, the contract NAA closed with the British contained a clause to deliver the fourth and tenth production Mustang to the USAAC for testing and evaluation purposes.
Construction number 73-3101 was the fourth production Mustang (often incorrectly cited in various books, articles and website as AG348, which is not the case, AG348 was production number 73-3102).
However, since the commitment to provide the Army Air Corps with an example was now two months behind schedule, an Allison engine belonging to the Air Corps had been rushed to the plant and installed on airframe 3101 so it could be rushed out in advance of the rest.
Because of that, 73-3101 became the second NA-73 to fly when Bob Chilton made the first test on May 20th, a power calibration and aileron trial flight. As an official Air Corps type, the plane bore the designation XP-51 and was given US serial number 41-038. Some of the parts were still handmade, not yet standard production pieces, and even some AT-6 components were still used.
Chilton flew 21 more tests in the XP-51 from May 24th to July 2nd.
For an in-depth review of both XP-51 airframes and the struggle to get accepted by the USAAC Materiel Command, please read our XP-51 article.
Fourth production NA-73 Mustang Mk. I, the first to be delivered to the USAAC for testing. As such it was designated XP-51 by the USAAC and serialized 41-038
The second production airplane, AG346 (c/n 73-3099), was the first airframe with full armament installed. It made its first functional check flight on July 3rd at the hands of Chilton.
The third production Mustang, AG347, had its first check flight on July 30th. This particular airframe also remained with NAA for developmental testing through March of 1942.
By August 1stt, Chilton had completed company tests on AG346 and it was now ready for British acceptance. Squadron Leader (later, Wing Commander) Michael N. Crossley, an RAF ace who had downed nine German planes while flying Hurricanes during the Battle of Britain, arrived from England to perform the acceptance test flights.
Wing Commander Christopher Clarkson, who was responsible for producing the pilot’s handbooks on all the American aircraft built for the RAF, also flew the Mustang.
AG346 was finally accepted in August.
“At the last minute, Michael Crossley hit the left brake, spun the plane around so the nose was facing the wind, put the mixture control in idle cutoff at 1,200 rpm, and moved the throttle fully open. In a couple seconds, the engine ceased firing and the pilot turned the ignition switch to off along with both fuel selector valves. To ensure against accidentally starting, Crossley left the mixture control lever at idle cutoff, reached up with his left hand, and unfastened the canopy. As the men gathered around, Crossley said “Wrap it up, chaps!” and began to unfold himself from the cockpit.”
Jimmy Beaton, who had worked for NAA servicing the new fighters for just a couple months, recalled decades later that, “I never could quite figure out how Mike got in and out of the Mustang’s cockpit. He was 6-ft 2-in tall and the Mustang’s cockpit was designed for a much smaller man. Watching him get in and out was a bit like viewing a circus contortionist.”
Michael “Red Knight” Crossley was mild-mannered and his quiet sense of British humor was greatly appreciated by NAA workers. However, his mild manner was a façade. Crossley had joined the Royal Air Force in 1936 at age 24 and trained as a fighter pilot. He was quite well educated, having attended Eton College and The College of Aeronautical Engineering. Rising rapidly in the RAF, Crossley became a flight commander on the eve of World War II. Flying with No. 32 Squadron, Crossley entered aerial combat during the Battle of France.
By the start of June 1940, he had destroyed six Luftwaffe aircraft, including four Bf 109Es while flying Hawker Hurricanes.
With the defeat of the British Expeditionary Force in France, Crossley escaped back to Britain and took command of the squadron and helped whip the unit back into fighting shape. During the Battle of Britain, he shot down a further 10 Luftwaffe aircraft between 12 and 18 August. During that same month, he was also shot down twice, but survived with minimum injury. By late August, the squadron was stood down for rest.
During April 1941, Crossley was assigned as a test pilot for the British Air Commission and sent to the United States where he flew Mustangs and a variety of other aircraft scheduled for shipment to Britain. At NAA, Crossley became one of a small and tight-knit group responsible for making sure that the Mustang was ready for combat in the skies over Europe.
Edgar Schmued described Crossley: “He was a very pleasant Britisher, 6 feet 2 inches tall, but the cockpit was designed for a 5-foot 10-inch pilot. When he sat in the Mustang cockpit, his knees were just about under his chin, but he didn’t complain. After he made his routine flights, which were most satisfactory, he had one more test to do: firing the guns out over the Pacific
Ocean. “Such gun firing had to have Coast Guard permission, which was a few weeks coming. The impatient officer complained to me: ‘I don’t understand you Americans; we in England just fire into the countryside, and you would be surprised how few people get killed,’ and out he went, complaining about the delays.” Fortunately, the Navy later made their firing range at North Island available for ground firing tests.
Pictured above is Michael Crossley with an unidentified NAA employee, standing in front of NA-73 Mustang Mk. I AG347.
As early testing continued meanwhile, some problems came to surface which needed correction. One of the problems was with the radiator ducting. Lee Atwood commented, “The upper edge of the intake duct had been made to be flush with the bottom surface of the wing, and we soon found that the air flowing along the surface in front of the duct became a turbulent, irregular pattern as it entered the duct and caused an audible rumble and vibration, which was unacceptable. Also, it was thought that the opening should be larger for cooling on the ground at low airspeed, so a fold-down front panel was provided to admit more air for ground operation. This leaked pressurized air and caused considerable drag."
Both these problems required that some redesign and refinement be made. Capable aerodynamics people like Ed Horkey and Irving Ashkenas, worked very diligently on the problems, using round-the-clock wind tunnel duct models and flight test measurements to arrive at the optimum configuration of a fixed intake with rounded lip edges. Also, the intake was moved down some 2 inches to provide a gutter or scupper for the thin layer of turbulent air to bypass the intake.
During some test flights and under certain condition an odd banging was heard by Chilton and other pilots. This was traced to the air intake atop the cowling. The intake was too short and this caused the airflow to resonate somewhat like a pipe organ. The intake was moved further forward, as much as possible, right up to the spinner. After this modification, the banging went away.
NA-73X testing also proved earlier that, at high angles of attack, the ram air delivery to the carburetor was cut-off, thus potentially starving the engine of air. This was also remediated by moving the air-inlet-scoop further forward, as far forward as possible, right up to the spinner.
Trouble with the ventral radiator opening and ducting was more difficult to eliminate. Turbulent air flowing along the bottom of the fuselage would go in at the top of the scoop and upset the internal flow. Originally, top line of the radiator duct was in line with the bottom of the fuselage and this was generating turbulence (Schmued had originally designed the aircraft without the gutter and with a variable area entry and exit on the cooling duct). Irving Ashkenas, who later went to Northrop and helped design that company’s Flying Wing, suggested that if the duct opening were dropped a few inches from the bottom line of the fuselage, the turbulent layer of air would then boil past the entrance, while the smoother flow would enter the duct. Horkey and Ashkenas tested the theory in the wind tunnel and it worked. Once this entry design was perfected, the variable area inlet feature was eliminated and an adjustable chute at the aft end of the duct controlled the volume of air flowing through it.
On August 24th, 1941, the first XP-51, 41-038, was also accepted by the USAAC and an Army pilot flew it to Wright Field.
Six more Mustangs were accepted in September, beginning with the fifth production Mustang, AG348 (c/n 73-3102), in which Chilton began production functional tests on September 19th, 1941.
AG348 was the final production Mustang sporting the short carburetor nose intake (41-038 was originally delivered to the USAAC with the short intake, but was later also modified with the longer scoop). This airframe was also the end of any hand-tooled parts, NAA’s production line was now in business. It later also had the distinction of being the first Mustang later shipped to the U.S.S.R. by Britain.
The tenth production Mustang, which was also to be delivered to the USAAC, was construction number 73-3107 and was given US serial number 41-039.
With four dummy 20-mm cannon installed on AG347, two on either wing, Chilton conducted a series flying tests on October 30th to determine the amount of drag they produced on this Mustang Mark I airplane.
The RAF received its first Mustangs Is in October of 1941, considerably behind schedule. The second production Mustang, AG346 (c/n 73-3099) was the first. It was disassembled and fitted in a stout wooden crate in preparation for the hazardous ocean voyage. The merchandman carrying AG346 had been bombed by enemy aircraft enroute to the UK, but the airplane was luckily undamaged.
It arrived safely in Liverpool on October 24th, 1941. The Mustang was taken to Speke Aerodrome where it was uncrated, assembled by No.1 Aircraft Assembly Unit and flown to the Aeroplane and Armament Experimental Establishment (A&AEE) at Boscombe Down, Wiltshire, to begin Service Trials. It was fitted with British TR 1133 VHF radio, a Mk. II reflector gunsight and British specification oxygen connectors.
AG346 could not be flown over British soil however, until British anti-aircraft batteries and RAF fighter squadrons could be briefed, as it was found that the Mustang looked too much like an Me-109 and might be shot down.
AG346 is crated and readied for its cross-Channel journey
The first test flights in the UK confirmed the results recorded with the NA-73X and AG345.
On the P-51’s first demonstration flight, an American test pilot put it through a 500-mph dive and several low-level speed runs. RAF officials at first refused to believe the performance data, and the flight had to be rerun.
Many British pilots were assigned to fly the first Mk. Is, and they all found the new fighter very satisfactory in its designed role.
Early test results produced healthy performance figures of 375mph at 15,000ft compared to the Spitfire Mk. V, which could only reach 340mph at the same height. Extensive testing of AG346 revealed that up to 20,000ft the Mustang was faster than any other fighter in service with the RAF at the time.
Speed was measured at 382mph at 13,000ft, and between 7,000 and 20,000ft the Mustang was averaging up to 30mph quicker than the Spitfire. Climb rate, acceleration, dive speed, stability, general handling, rate of roll and radius of turn were recorded from being satisfactory through to outstanding. It was the range and endurance that made the Mustang stand out from other fighters of the day. The Spitfire had an average range of 400 miles and an endurance of just 2 hours, while the Mustang, even in unfamiliar hands, could stay airborne for 4 to 5 hours and cover over 1,000 miles without drop tanks!
Of the next six Mustangs that arrived, three more (AG351, AG357, and AG359) were sent to the Air Fighting Development Unit (AFDU), and three went to the A&AEE for the accelerated testing required to evaluate the new American fighter.
NAA ramped up its production capabilities and deliveries for the RAF accelerated rapidly, with 135 Mustangs accepted by year’s end (AG346 and AG348-AG351 (5) in September, AG352-AG377 (26) in October, AG378- AG414 (37) in November and AG415-AG481 (67) in December.
During December 1941, NAA was building 3.5 Mustangs per day to fulfill the British order, but Kindelberger stated he could raise production to a whopping ten fighters per day within three weeks of a substantial Army order.
During the month of December, more Mustangs were allocated both to Operational Training Units (OTUs), beginning with No. 41 OTU, and Army Co-operation Command squadrons, including Nos. 4, 26, and 241. Most of the first 20 Mustangs to arrive in England were used for test and evaluation.
At Liverpool’s Spekes Airport, the British press and VIPs were shown the Mustang, along with the Curtiss Kittyhawk, on December 5th, 1941. Most of the Kittyhawks went on to serve with squadrons in the Middle and Far East.
The most serious concern with the Mustang however was the engine. The Allison V-1710-39 (also known as -F3R) engine provided 1,150 horsepower. The problem was the rapid fall-off in performance at altitudes above 15,000ft.
Although the Allison did incorporate a gear-driven supercharger, it was optimized for low-altitude operation. This was more than just a minor deficiency, since most aerial combat over Europe at that time was taking place at medium to high altitudes.
Another criticism was the position of the fighter’s low-slung radiator, which received a substantial blast from the propeller on the ground. While this obviously aided cooling, there was also the high chance, on a loose surface, of the propeller throwing up small stones or any other loose matter. Airfields with concrete runways and dispersals were not seen as an issue, but grass airfields, such as Boscombe Down at the time, could present an operating hazard.
Consequently, the Mustang was rejected by RAF Fighter Command and it was decided that it could be best used for low-level tactical reconnaissance and ground attack, where full advantage could be taken of its exceptional low-altitude performance and long range. All of the Mustang thus went to the Army Co-operation Command.
For these types of missions, the Mustang Is had two K-24 camera’s installed: one just aft of the pilot’s armor on the left side, pointing left and rear and the second just aft of the radiator, shooting straight down.
A single gun camera was also added near the left wing tip.
British Mustang Is were painted in a camouflage scheme with yellow stripes being added across the wings to keep them from being confused with the Luftwaffe’s Bf-109’s. In the heat of the fight one could easily confuse the Mustang with a Bf-109 (In fact there were occasions where a Messerschmitt pilot joined formation with a group of Mustangs before realizing they were actually not the friendly aircraft they thought they would be and vice versa).
The RAF later found that reconnaissance missions could also be combined with more aggressive actions. The Mustang proved to be an accurate bomber, was able to provide ground support, fight its way out of a jam and could take on a Messerschmitt Bf 109 or Focke-Wulf FW-190 on fair terms at low altitude.
Deliveries of airframes AG482 – AG565 (84) in January and AG566 – AG664 (99) in February concluded the first batch of 320 aircraft.
Kindelberger sent a letter to Wright Field on February 2nd, 1942, its subject line read: “Production of P-51 Mustang Fighter Airplanes. In part, this programme update letter stated, ‘...a total of 620 airplanes had been ordered by the RAF at this time. Under the Defense Aid program, 150 additional were ordered by the Army, making a total of 770 aircraft ... approximately 220 airplanes had been delivered and that the production rate is now 78 airplanes per month. Starting about March 1, the production rate will be 104 per month. At this rate the fighters will all be delivered by August 1942 and no additional orders have been indicated.”
Not all Mustangs arrived in the UK without incident however. On February 8th, a convoy transporting Mustangs was attacked by German U-boats. U-108 sank British freighter Ocean Venture off Cape Hatteras, Virginia and most of its crew and 12 Mustangs it was transporting were lost. Fourteen survivors were rescued the next day. In another U-boat attack just a few days later, a further eight 8 Mustangs were lost at sea.
February 13th saw the initial production functional flight of AL958 with Chilton at the controls.
AL958 was the first Mustang Mk. I of the second batch of 300 Mustangs for the RAF. Seen here on a test flight in the US and sporting US markings.
This was the first of 300 aircraft of the second order. Because they were part of a different contract, they were produced under NAA contract number NA-83, but these were practically identical to the NA-73 block.
Within RAF service, they also carried the Mustang I name.
In a request for installing Continental engines in the Mustang, Rice wrote to Atwood on February 23rd: “Cooling requirements for Continental engine require far larger radiator/intercooler, significant redesign of the airframe, and unsuitable for incorporation in the Mustang.”
On February 26th, Atwood sent a letter to O.K. Hunt, the Allison Chairman, to seek prioritization of the two-speed/single-stage supercharger over Allison’s proposed two-speed/two-stage supercharged V-1710-45. This was mainly done because of the extra length that came with the auxiliary second-stage supercharger. With that extra lentgh needed from the firewall to the propeller, the engine could not be housed in the NA-73 airframe without moving the wing further forward.
Rice sent a report which contained the main differences between NA-73 and NA-83 to R.C. Costello:
On April 16th, NAA would finally get a contract order (AC-27396) from the USAAC. It was in dire need for a dive bomber and NAA got the go-ahead. To learn more on how NAA procured that contract, please visit our A-36A Mustang history page. The A-36 would be give NAA charge number NA-97.
From May to August 1942, AG351 was used for fuel consumption trials at Boscombe Down. The aircraft was flown at an AUW (all up weight) of 8,300lb. At this weight, the still-air range of the Mustang at 15,000ft was 8.75 mpg at 180mph IAS (indicated airspeed). The results of the test were slightly marred by the fact that AG351 only had a fuel capacity of 130 imperial gallons, when all later aircraft carried 140 gallons. AG351 still managed to fly for a maximum range of 990 statute miles, and had an endurance of 4.1 hours.
Test results of AG351 can be found here.
AG351 was also used for elaborate gunnery trials (December '41 through late January '42), along with AG359 (February '42 through May '42). These tests included gun mounts, feed mechanisms, expended case and link arrangements, gunsights, armament servicing, and nose gun synchronizing gear.
Those trials revealed several issues with the armament. A significant list of proposed modifications was made in order to make the armament fitted to the Mustang I more suitable for RAF operational usage. An important issue were the inadequate strength of the wing gun mounts. There was even an occastion where, whilst firing a long burst in ground fire trials, a wing-mounted .50 cal broke free from its mount and caused subsequent damage to the wing.
Modification to the wing mounts and to the locking mechanisms were made to resolve the issues.
The rubber ejection chutes (for ejecting empty shell cases) also caused several stoppages as they flexed when the guns were fired. On other occasions, the ejected shells would become stuck in the chutes, blocking the entire gun feed mechanism. Chemical and oil residue from cleaning and maintaining the gun mechanism and shells also caused a deterioration on the rubber chutes, as did the fluctuation in temperatures.
New thin sheet metal empty case and ejection chutes were designed and tested by the A&AEE, which took care of those worries.
In total, over 20 modifications were proposed. These were passed on to NAA engineers, who took those issues into consideration for later production batches of the Mustang.
Another "problem" for the RAF were the US supplied and installed .30cal Browning guns, which required the standard US .30cal 30-06 round. The US rounds were of different design with regard to the standard RAF 0.303in. rounds used in the RAF version of the Browning machine gun. The RAF examined making the change to the British-built .303in guns, but is was concluded that that would take up too much effort, so the US Brownings were maintained.
Mustang Mk. I AM106/G was tested with underwing gondolas for 40mm Vickers “S” guns, whilst another airframe, AG357, received eight rails for air-to-ground rocket projectiles.
AM118 was also retained at NAA and would go on to serve as a testbed for the A-36.
The not so bright outlook of the Mustang would come around when Rolls-Royce chief test pilot, Ronald T. ‘Ronnie’ Harker, flight tested an Allison-powered Mustang Mark I (RAF serial number AG422) at RAF Duxford in Great Britain on April 30th, 1942. He noted that “with a powerful and good engine like the Merlin 61, its performance could be outstanding”.
The very next day, he sent a letter to Rolls-Royce suggesting the installation of a Merlin 61 engine in the Mustang to see if it would improve its performance above 15,000 feet which he found to be dismal with the Allison engine.
He also suggested that a variant of the Merlin built in the US by Packard, such as the V-1650-3, be fitted and tested in a P-51A in America.
This conversion would greatly affect the course of the war in the years to come...
You can read all about it in our XP-51 chapter.
Four British airframes were sent to the Soviet Union in May: AG348, 352, 353 and 354.
By July of 1942, the last of 620 Mustang Is had been accepted by the RAF.
The Mustang I entered operational service on January 5th, 1942, when Wing Commander W.D. Butler’s No. 26 Sqn based at Gatwick, Surrey, received AG367 (coded RM-Z) for operational tests. The Mustang would replace the mix of obsolescent Lysanders and Tomahawks.
The squadron received two more examples (AG364 and AG387) on January 29th.
The new Mustang was fast at low level, well-armed and, to fit its new reconnaissance role, was fitted with a port-facing oblique F24 camera just aft of the pilot seat in the cockpit. Months later, a second, vertically positioned camera for higher-level survey photography, would be added.
In April, two more squadrons received Mustangs, and eight more followed in June (Nos 2, 4, 16, 255, 239, 241, 268 and 613 (City of Manchester) squadrons).
After working up and training, 26 Squadron began operations early on May 10th, when Flying Officer Graham Newstead Dawson from flew AG348 for the Mustang’s first operational combat sortie over the European mainland. The mission was a low level photo reconnaissance in Northern France. After gaining the necessary intelligence, Dawson headed back hugging the terrain when he came across the airfield at Berck-sur-Mer in France, where he spotted several vehicles and packing cases. The temptation was too much and Dawson swept back across the airfield, strafing as he went at two hangars in the southeastern corner, before making off at high speed with a large amount of flak and machine-gun rounds in tow. A goods train also received a burst of fire before Dawson made his way back to Gatwick after being in the air for just 1 hour and 40 minutes.
The unit flew its second operation on the 14th when it photographed a radar site in the Pas de Calais area, near Le Touquet. They attacked targets of opportunity near Boulogne where one Mustang sustained slight damage from ground fire. This may seem an unglamorous task at first, but those reconnaissance missions were nevertheless vital in the planning for the invasion of France in 1944.
A few days later the Squadron moved the short distance to West Mailing from where on the afternoon of May 21st, three more Mustangs flew a recce to Le Touquet where they shot up the radar site and where the Mustang's first, albeit brief and inconclusive, brush with a German fighter took place.
Then seven days later a trio flew a 'Rhubarb' (fighter or fighter-bomber sections crossing the English Channel and then dropping below cloud level to search for opportunity targets such as railway locomotives and rolling stock, aircraft on the ground, enemy troops, and vehicles on roads) over the French coast, strafing troops near Merlimont south of Boulogne then coasting out further south at Cayeux. These flights were flown at low level, usually at around 240 knots.
After a slow start due to unsuitable weather (a ceiling of 1,500 feet and 7/10 cloud cover being required) during June, pace of operations grew with 26's Mustangs increasingly involved in operations such as Rhubarbs over France and a few Lagoons (shipping reconnaissance) off the Dutch coast. A typical sortie for the Squadron was on July 14th when three Mustangs operated in the Boulogne-Abbeville area, crossing the coast near Berck. Near Randerfleur they attacked railway rolling stock in the sidings as well as barges in the Somme estuary near Le Touquet - all in the face of heavy flak.
Whilst attacking one barge, AG415 was shot down - the first Mustang to be lost to enemy action. The pilot, 32-year old Pilot Officer Harold Taylor was killed.
Two days later three more flew to the same area, strafing a group of troops seen on a beach but in the low cloud they became separated and two of the Mustangs failed to return.
Gradually, the pace of these fighter-reconnaissance operations over occupied Europe increased, with No. 239 Sqn becoming the next unit to declare itself operational with the Mustang I in June.
WARNING: This section contains some explicit images!
Reconnaissance flights flown in early August gathered information for the raid on Dieppe (Operation Jubilee) planned for the 19th.
Operation Jubilee was conceived by Lord Louis Mountbatten. The intention was to land a large force of Allied troops at Dieppe and hold the port for a short period, to prove it was possible and also to gain any intelligence from the local German forces. The operation was never fully approved by senior military staff, but nonetheless began at 0500hrs on August 19th, with over 6,000 (mainly Canadian) troops involved. Allied aerial support involved a colossal 70 squadrons of aircraft including virtually all of the operational Mustang units available at the time.
This operation led to some of the heaviest air fighting of the war. The four Mustang squadrons of No 35 Wing - Nos 26, 239, 400 and 414 Sqns flew in support of Jubilee throughout the day.
No. 26 Squadron was tasked to provide the raiding force with tactical reconnaissance support to warn of the approach of enemy ground reinforcements from Le Havre, Rouen and Amiens. From the early hours of that fateful day the squadron sent out pairs of Mustangs, flying 16 sorties during the morning, first off being Flt. Lt. Dawson in AG418 with Plt. Off. Kelly in AG462 to cover the roads between Le Tréport and Evernay, landing back at 0610hrs.
Flt. Lt. Don Kennedy (AG536) and Sgt. Geoff Cliff (AG584) then went out, but both failed to return and were killed. Then from 0620hrs until shortly before 0800hrs Flt. Lt. Aubrey Baring in AG574 with Sgt. A. P. Bannerman (AM110) were on patrol then followed by Plt. Offs J. E.A. Hartill flying AG462 and R.J.Giles in AG535 who were succeeded by Plt. Off. J. A. Manson in AM215. Soon after this two more Mustangs set off on another tactical reconnaissance flight, but both Plt. Offs O'Farrell and Christenson were shot down in AG463 and AL977 respectively. Both became PoWs but Arnold Christenson was later shot by the Gestapo following the Great Escape from Stalag Luft III in March 1944.
At 0830hrs Sqn. Ldr. Mike Goodale in AM148 (RM-G) led AG531 flown by Plt Off. C. B. McGhee to the carnage over Dieppe where his aircraft was hit and on landing it suffered a brake failure and hit an obstruction. Shortly afterwards Flt. Lt. Graham Dawson took off in AG418 but the 21 year old did not return and was killed.
Wing Commander Fazan later recalled: "'At 50 feet or less we were inviting targets for any German soldier with a rifle. The element of surprise saved us a lot, but Dieppe was our most costly day."
The badly-planned invasion came at a great cost. By 0900hrs, the Allies on the ground were in full retreat and those in the air fared no better. By day’s end, 119 RAF aircraft failed to return compared to 46 lost by the Luftwaffe. Eleven of these losses were Mustangs, five from 26 Squadron, three from 239, one from 400 (City of Toronto) Squadron and a pair from 414 (Sarnia Imperials) Squadron.
No 26 Squadron flew 11 sorties that day, mainly around Le Havre, Rouen, Abbeville and the River Somme areas. No 239 Squadron flew 14 sorties, mainly low-level reconnaissance missions of the roads from Envernay and Blacy to Le Tréport.
The Dieppe raid did produce the Mustang’s first kill of WWII…
That day, Flying Officer Hollis “Holly” Hills, an American volunteer flying with No 414 RCAF Squadron, flying AG470, claimed a FW 190.
First Operational Mustang kill and loss
F/O. Hollis “Holly” Hills and Fl/Lt.. Fred Clarke had flown their first sortie at 0445 AM on the morning of the Dieppe Raid and were on their second sortie at 1025, a tactical reconnaissance south of the town of Dieppe. Holly was flying as “weaver” or cover for Freddie as he was to do a low level visual check of the road from Abbeville to Dieppe.
The squadron pilots had all been briefed about landing near the Dieppe race track if they were damaged or disabled but able to land. A Canadian corps was supposed to have secured this site during the morning for just such an eventuality but by the mid-day it had become all too clear that the raid was going badly.
As they neared the French coast, west of Dieppe, Hills spotted a flight of three FW 190s to the right at 1,500ft.
This is the encounter through his eyes: “A couple of miles short of landfall I spotted four FW 190s off to our right at about 1500 ft. Their course and speed was going to put them directly overhead when we crossed the beach.
I called Freddie twice with a “Tally ho!", but there was no response. He did not hear the warnings and apparently did not see the Fw 190s. When Freddie turned right to intercept our recce road at Abbeville, we were put in an ideal position for the FWs to attack. I swung very wide to Freddie’s left during the turn, dusting the Abbeville chimney tops. That kept me beneath the FWs, and I believe they lost sight of me.
My plan was to cut off the lead FW 190 before he could open fire on Freddie, but my timing went to pot when a crashing Spitfire forced me to turn to avoid a collision. That gave the lead FW pilot time to get into a firing position, and he hit Freddie’s Mustang with the first burst. I got a long-range shot at the FW leader but had to break right when his No 2 man had a go at me. The No 2 missed and made the big mistake of sliding to my left side ahead of me. It was an easy shot and I hit him hard. His engine caught fire, and soon after it started smoking and the canopy came off. I hit him again and he was a goner, falling off to the right into the trees.
The second pair of Fw 190s had vanished so I raced Towards Dieppe looking for Freddie’s Mustang. I saw him heading for the harbour at 1000 ft, streaming glycol, with the lead FW trailing behind. The FW started to slide dead astern Freddie, so I gave him a short high-deflection burst to get his attention. He broke hard left into
my attack, and the ensuing fight seemed to go on forever. I could out-turn him, very slowly gaining an advantage, but just as I got into firing position he would break off and streak inland, using the superior power of his BMW engine. He would come back at me as soon as I turned to head for the coast, and we’d start our turning competition all over again. During one turn I had to dodge a crashing aeroplane - an Me 109 - and the FW pilot got his only shot at me. His deflection was too great and he missed. My opponent was a highly competent pilot, and I was ready to call a draw as soon as I could.”
Fl/Lt. Clarke was oblivious to the action that was unfolding above his head until the first shells slammed into the oil cooler of his aircraft's Allison engine: "The next thing I know is 'all Hell and corruption ’s going by.... I'd been hit.... The radiator was shot up; my instruments on either side of me were gone. The armor plating saved me. So I jettisoned the hood hoping that it hadn't been jammed with the shots, and it wasn't. And I thought, 'They're right, it's nice, not windy in here at all. '... "
Clarke Instinctively he twisted his aircraft into a hard climbing right hand turn: "I got about 800 feet. That's all she'd get. "
Without his radiator he knew that it was only a matter of time before the engine seized completely. Although the pilots had been offered the inland race track as a potential crash landing site, he had no intentions of risking capture, and preferred instead to take his chances in the channel. He would never have made it had it not been for the timely return of Hills to the scene of his leader's obvious distress.
Clarke continued in his struggle to reach the water. It was a perilous moment, considering that no one had been known to "ditch" a Mustang and survive, principally because of the large air scoop under the belly that acted as a rather unfortunate rudder, directing the nose of the aircraft immediately toward the bottom. This did not happen in Clarke's case. Unfortunately it is still unknown as to exactly what did happen in the last seconds of the crash landing. Fl/Lt. Clarke's memory has survived only to include the moment above the water at 10 feet, an airspeed indicator reading 90 knots, and the moment when he woke up in the bottom of a landing craft:
After being treated for the wound to his head Clarke finally returned to Purley where he and Holly were billeted in a requisitioned house.
On his return to the squadron the morning of August 20th, Fl/Lt. Clarke confirmed seeing a FW190 crashing in a steep dive into the ground. This was deemed to be the one that F/O. Hills had first fired on.
Freddie Clarke was the last surviving member of the original 414 pilots who formed the squadron on August 7th, 1941. He passed away in Calgary, Alberta, Canada in May of 2005.
Hollis Hills later became an ace flying Grumman Hellcats of VF-32 for the United States Navy. He passed away on October 31st, 2009 in Melbourne, Florida and was buried in Arlington National Cemetery in Arlington, Virginia with full military honors.
Back home, newspapers reported the successes but didn’t mention the losses.
Hill’s success was not the only one on August 19th, as a pair of No 268 Sqn Mustangs also claimed a Ju 188 destroyed.
Crating a Mustang
Developing and producing Mustangs was one thing, getting them all over to the frontlines in the UK and the Mediterranean Theater was another. At NAA, a dedicated bunch of people was tasked with figuring out how to do just that.
At the beginning, the Mustangs were disassembled into smaller pieces and engineers had to figure out the easiest, most compact way to box them for shipping. Once done, a template was made for a rig and crate and a guideline was written down on how to proceed.
The following are fragments out of the Maintenance and Erection manual to give you all an idea how this was done. This is not complete and is not meant as a guideline on how to disassemble and crate a Mustang for private Mustang owners!
The first production models were disassembled into smaller pieces, as described below, crated and put on transport ships across the treatorous and U-boat filled Atlantic.
Instructions on how to dismantle the Mustangs to prepare them for shipping in custom built crates, as noted in the Maintenance & Erection manual:
A. Protective measures during general dismantling
B. Dismantling plane for crating
The crates were built from North American Aviation drawings and were lined on top and sides with tar paper so lapped that any water entering seams will drain out the side seams at the bottom of the crate.
For crating itself, the following procedure would have been followed:
At a later stage of the war, Mustang would also sometimes be transported on the deck of an aircraft carrier. In that case they were also disassembled, albeit to a lesser extent (wings were not taken off) ...
From time to time, Mustangs were used as fighter escorts on medium or low level bombing missions. The first long range bomber escort mission, outside of the range of Spitfires & Hurricanes based in the UK, was by Mustangs of No.268 Squadron. They escorted Bostons of No.88 Squadron RAF for a raid on Den Helder in the Netherlands, on September 16th, 1942.
As well as reconnaissance missions, the expanding force of Mustang I squadrons also regularly mounted more offensive sorties in the form of ‘Rhubarbs’, ‘Rangers’ and ‘Populars (photo reconnaissance missions)’. These led to occasional brushes with the Luftwaffe, and a steady stream of losses mainly to light flak.
Another controversy: first operational German border crossing by a fighter in WW2
Now for some other controversy: many books and websites state that on July 27th, 1942, 16 RAF Mustangs undertook their first long-range reconnaissance mission over Germany, making this the premiere crossing of an allied fighter over the German border. I have yet to find any evidence of such a mission.
Documented in the journals of No 234 Squadron is a mission on July 27th, 1942. On that day, 12 Mustangs from No 234 Sqn, one of which was flown by Danish Pilot Officer Jørgen Thalbitzer took off on a mass rhubarb over northern France accompanied by eleven other aircraft. They carried out low-level attacks on a number of targets between Plouescat and Guissény in Brittany. They were intercepted by German fighters and also hit by flak and machine-gun fire from Landerneau. Thalbitzer’s aircraft was hit and his engine stopped. He managed to make an emergency landing near Plouescat. He was unhurt, but was soon taken prisoner by the Germans. He was one of four pilots shot down on the mission.
Furthermore, why Army Co-operation Command Mustang would venture alone on photo-reconnaissance missions over the German border so early in the war, seems very unlikely. There were a lot of more important reconnaissance missions to be done near the French coast to seek out opportunities for an Allied invasion.
The actual first documented mission of Mustang Mk. Is over Germany would be on October 21st, when four Mustangs of No. 268 Squadron flew from RAF Bury St. Edmunds on a mission to the Dortmund-Ems Canal and other objectives in Holland.
The Mustangs made a refueling stop at Cottishall and from there made their way to a point near Texel, Netherlands, then on to a point near Heede in Germany. They then commenced attacking targets such as hutted camps, canal traffic on the Dortmund-Ems Canal, a gasometer and factory at Lathen, then attacking a number of small ships and tugs on the way out over the Zuider Zee and the Netherlands back to the UK.
That day, Mustangs became the first single-engined fighter based in the UK to penetrate the German border. The mission was led by Wing Commander A. F. Anderson, with Flt. Lt. B. P. W. Clapin, Plt. Off. O. R. Chapman RNZAF, and Flg. Off. W. T. Hawkins RNZAF. This mission caused a great deal of consternation to the German High Command, as the presence of single engined RAF fighters operating from the UK over Germany meant that a new level of threat had to be considered.
Please also note that those Mustangs did not escort Wellington bombers on a raid to the Dortmund-Elms Canal on October 22nd. The Mustangs conducted their sortie some 12 hours before the Wellingtons made theirs that night over the same area (The confusion comes from multiple editing of the original RAF Official Communique for that day which lists the two sorties separately. The communique was edited afterwards for transmission from the UK to the USA, reducing the word count, followed by further editing by the press agency which released the details to the various news services in the USA and those merged the two distinct operations into one. That was then printed in multiple US newspapers at the time). Again, this makes sense. Mustangs were still not considered as escort fighters at that time, they were still being used for tactical reconnaissance missions. Furthermore, RAF bomber command was devoted to night time bombing raids over Germany, which obviously would not have Mustang fighter escorts.
Below, we discuss the design of the Mustang Mk. I and the design changes with regards to NA-73X.
The elements listed below are all taken from official Mustang Mk. I manuals and documentation. This list is in no means final or complete.
The Mustang I is a high speed fighter-pursuit monoplace airplane armed with four .50-caliber machine guns and four .30-caliber machine guns.
Handling and General Maintenance Instructions
Steps, handholds and walkways
Surface Control Lock
Radiator Air Scoop
Footsteps and Handholds
Cockpit Sealing Bulkheads
Landing Gear, Wheels & Brakes
Main Landing Gear
Controls and Warning Lights
Engine, Propeller & Cowling
Engine Primer System
Radiator Air Scoop
Pitot Static System
Power Plant Electrical Equipment
Landing Gear Position Indicator
Pitot Tube Heater
Armament - Gunnery Equipment
Guns & Ammunition Bays
Cockpit Weapon Controls
Miscellaneous & Emergency Equipment
Cold Weather Provisions
Propeller Anti-Icer System
Propane Primer System
Oil Dilution System
Miscellaneous Cold Weather Provisions
First Aid Kit
Cockpit Comfort Equipment
Cockpit Heating System
Aircraft Destruction Mechanism
Pilot Relief Tube
Map and Data Cases
Handling and General Maintenance Instructions
Steps, handholds and walkways
A flush-type handhold and a step are located on the left side of the airplane. The wing-to-fuselage fillets constitute the walkways, which are located on each side adjacent to the fuselage.
a. Hoisting Points—Provisions have been made on the upper surface of each wing section to install hoisting shackles (NA 36-55009) which are located directly above the wing jacking points The hoisting points utilize the same structural member as the jacking points. A screw flush with the upper surface of the wing must be removed to install the hoisting shackles. When using the wing hoisting points to hoist the complete airplane, the hoisting sling (NA 73-55015) must be equipped with a spreader bar so that the pull will be perpendicular to the horizontal axis of the airplane. Under no circumstances should the cable arrangement be allowed to exceed a 30° departure from the vertical. Since the center of gravity location of the airplane is near the wing jacking points, a weight of 200 lbs. should be suspended from the lift tube when hoisting the complete airplane with the power plant installed.
b. HOISTING Lugs—Hoisting lugs are provided at the upper end of each engine mount arm. These lugs can be utilized to hoist the complete power plant and also to hoist the complete airplane.
Two wing jacking pads (NA 97-55008) are provided for the wing jacking points located on the lower surface of the left and right wing section just outboard of the gun mounts. The tail wheel jacking point is situated on the lower surface of the ftiselage aft of the tail wheel. A jacking point inboard of each main landing gear at the bottom of the fork can be used when the airplane is in the three-point attitude The jacking point on the wing center rib just aft of the firewall is to be used only when the fuel tank doors are to be removed.
The leveling lugs are located aft of the pilot's seat on both upper longerons.
a. PARKING BRAKE - A parking brake control handle is centrally located below the front instrument panel. To apply the parking brakes, pull out on the control handle and press both brake pedals to their full extent: release the brake pedals and then release the control handle. To release the parking brakes, depress both brake pedals.
b. MOORING—Mooring rings are fitted on the lower surface of each wing, slightly aft and outboard of the gun mounts. The rings are held flush within the wing surface when not in use. Pry at the forward part of the rings to disengage them from the stowed position. Prior to mooring the airplane, head the airplane into the wind. Then set the parking brakes, lock the surface controls, and lock the tail wheel. Lash the tail of the airplane only by means of the lift tube. If no fixed mooring anchorage is provided, standard airplane mooring kit. Type D-l, will be used.
A mooring kit was attached to the left side of the fuselage in the rear compartment.
A towing ring is installed at the inboard side of each wheel axle. If tow ropes are used, the length of the tow ropes should be at least 12 feet. When a tow bar, TJ 4113. is available, the airplane may be towed by inserting the angle hooks of the tow bar through the towing rings. When towing, the tail wheel must be unlocked and a man should be stationed in the cockpit to operate the brakes, and a man assigned to each wing tip when moving on the ground near other airplanes or obstacles. Never tow the airplane by means of the tail wheel.
One set of dust-excluder covers is furnished with the airplane for the cockpit enclosure, engine, propeller spinner, front air scoop, the landing gear torque link, and the landing gear wheel wells. The engine cover extends aft to protect the pilot's cockpit enclosure.
Each Mustang comes with a custome tool kit, which exists of the following:
The Curtiss propeller came with the following tools:
The wing has a span of 37ft 5/16in and is a full-cantilever, nonadjustable structure consisting essentially of a right and a left wing section, removable tips, ailerons and flaps.
The airfoils are of the laminar-flow type (see NA-73X for details) developed at North American Aviation, Inc.
The empennage consists of a horizontal stabilizer and vertical stabilizer, semimonocoque in design, which are full-cantilever, nonadjustable structures.
The wing is semimonocoque in design, containing a main spar, an aft spar, and an auxiliary spar, the latter situated at the landing gear wheel well. The spars are made out of aluminium alloy.
The wingtips are of aluminium alloy and can be detached by means of screws.
The wings provide for the installation of the machine guns and ammunition, external racks, self-sealing fuel tanks, navigation and landing lights and the main landing gear.
The horizontal stabilizer is constructed as one unit with detachable tips.
It consists of a forward and aft spar of 24ST alclad material and is attached to the rear section of the fuselage by means of bolts.
The vertical stabilizer consists of a foward and aft spar of 24ST alclad material.
The ailerons are metal-covered and of the sealed-type, installed just inboard of each wing tip.
They are controlled by lateral movement of the control stick in the cockpit, connected by tinned-steel control cables and pulleys.
The trim tabs are made of plywood. The aileron trim tab control is mounted on the port side of the cockpit. Rotating the aileron trim knob clockwise results in the right wing going down.
The elevators consist of 18 flanged aluminium ribs, one main front spar, a V-section trailing edge and a short intercostal beam.
They are fabric covered (grade A mercerized cotton) and attached to the trailing edge of the horizontal stabilizer.
The right- and left-hand elevators complete with the plywood trim tabs installed are interchangeable.
The ailerons are controlled by lateral movement of the control stick in the cockpit, also connected by cables.
The elevator trim tab control is mounted on the port side of the cockpit. Rotating the elevator trim knob clockwise results in the nose going down.
The rudder structure consist of 20 flanged aluminium ribs, one main spar, a V-section trailing edge and a short intercostal beam. It is also fabric-covered and is attached to the trailing edge of the vertical stabilizer. The trim tab is also made of plywood.
The rudder is controlled by the rudder pedals in the cockpit and is connected via cables.
Conventional rudder pedals are provided and are adjusted for length by means of a release on the inboard side of each pedal. When the release is pushed inboard, the pedal is free to move forward of aft without moving the control cables. The spring-loaded mechanism automatically locks the pedal when the foot is removed.
The rudder trim tab is mounted on the port side of the cockpit. Rotating the rudder trim tab clockwise results in the nose veering right.
The wing flaps are metal-covered sealed aileron-type wing flaps, and are installed on the trailing edge of each wing between the fuselage and the ailerons.
The main section consists of 2 spars, 12 nose ribs, 11 main ribs and a series of rolled section stringers.
They are operated by hydraulically actuated struts located in the fuselage just above the front radiator scoop. The movement is selectively controlled by means of the flap control handle on the aft end of the port control pedestal in the cockpit. The lever clicks into each of the three positions: UP, NEUTRAL, DOWN.
-To partially lower or raise the flaps, put flap selector to DOWN or UP, and return selector to neutral when the desired position is shown on the flaps position indicator.
On AG664 and earlier aeroplanes, the hydraulic control knob must be pushed in before the flaps can be operated.
The sector is slotted in the positions which indicate each 10° of flap movement from 0 to 50°.
controlled by a lever on the left hand side of the cockpit.
Surface control lock
The ailerons and rudder can be locked in the neutral position, and the elevator in the neutral position of down position, by means of the surface control lock in the cockpit.
It is located at the bottom and just forward of the control stick.
To lock the controls:
(1) Push the control stick to its forward position.
(2) Press the latch on the forward side of the control lock and pull the lock assembly aft of the control stick.
(3) Pull the knob on the left side of the control lock assembly, center the stick so that the control lock plunger is in line with the desired hole in the control stick collar and then release the knob.
To unlock the controls: pull the knob on the left side of the control lock assembly, move the control stick aft, and then release the control lock assembly.
The fuselage is semimonocoque in design and. with the exception of the armor plate firewall and the armor plate aft of the pilot's seat, is fabricated entirely of aluminum alloy.
The fuselage is divided into 3 sections: the engine mount, main section and tail section. All sections are separable, being attached with bolts.
The main fuselage section is of the four-longeron type. The upper longerons are H sections extruded from 24ST bar stock. The longerons extend from the firewall and terminate in a tapered form slightly forward of the aft end of the section.
The lower longerons extend the full length of the section.
The skin along the sides of the cockpit is of .081 -inch 24ST material: aft and at the sides of the radio compartment 064-inch 24ST material:
above the radio compartment and to the end of the section 040-inch 24ST material.
The skin is butt-fitted and flush-riveted.
An A-shaped structure, integral with the fuselage section and situated aft of the pilot's seat, serves as a nose-over structure. A semielliptical cutout at both sides of the fuselage, directly aft of the nose-over structure, is provided for rearview windows. A shelf aft of the pilot's scat and another forward of the tail section serve as shear shelves.
A 24ST aluminum alloy tube is installed in the aft lower end of the section for lifting and tying down the airplane.
The firewall is a combination armor plate and firewall attached to the fuselage by means of bolts.
The outer portion of the firewall is a .354-inch steel plate with the center consisting of a 019-inch stainless steel sheet. The steel plate is constructed in 3 sections which arc spliced together The stainless steel sheet is indented to provide for the installation of the oil tank.
Stainless steel angles are attached to the outer forward edge of the firewall for attachment of engine cowling Dzus fasteners and aluminum alloy angles are utilized at the aft edge of firewall for attaching the windshield cowling and fuselage covering.
The firewall provides for installation of the oil tank, power connecting panels, fuel booster pump, and fuel strainer.
The side panels of ihe windshield are of laminated glass and the upper panel is of plastic sheet material.
The forward flat section of the windshield is armor plate glass made of crystalline high-test multiplatc, and consists of 5 plies made out of different thicknesses.
The windshield cowling extends from the lower forward end of the forward panel to the firewall and to the sides of the fuselage upper longerons. A shroud integral with the windshield extends aft and to the sides of the windshield. The edge of the shroud is covered with a circular rubber extrusion The shroud contains the windshield defrosting unit optical gun sight, dummy receptacle for stowage of the optical gun sight plug, 2 handholds, and stowage for the ring and bead sight.
On AG664 and earlier aeroplanes, an armour plate glass is mounted directly behind the forward windscreen panel. The armoured glass can be hinged down to enable the inner side of the windshield to be cleaned; the gun sight must first be hinged back.
The cockpit is covered with a flush-type transparant hood with sliding windows on both sides. The enclosure consists of 3 panels: an upper and 2 side panels.
The sections of the panels arc of plastic sheet material. Both side panels have 2 sections, the forward section utilized as a sliding window. The sliding windows are guided by an upper and lower stainless steel track and controlled by a window- locking handle The windows arc controllable from within the cockpit only. To open, pull back the handle at the base of the window and slide back.
The upper and right panels are hinged together, the upper panel hinging upward.
A linkage attached to both panels is used as a stop for the upper panel when opened.
The left panel lunges downward against the side of the fuselage.
The upper and left panels are provided with locking facilities controllable from inside and outside the cockpit. The inner control handle is situated forward and the outer control handle is situated aft and flush with the upper left panel frame.
To open the hood from Inside the cockpit, pull back the red lever, gently fold back the top panel and let the port panel down.
An emergency exit lever releases the hood for emergency egress.
Two windows, which may be easily removed for access to the radio equipment or camera installation, are provided aft of the cockpit The transparent panels are of plastic sheet material molded to fit the contour or the fuselage.
The windows are held in place by a spring at the aft end and two latches at the forward end. These latches may be released from the inside only.
Two sections of armor plate are provided behind the pilot's seat. The upper section is 7/16-inch armor plate and the lower section is 5/16-inch. The sections are bolted directly to the nose-over structure.
Radiator air scoop
Air inlet and outlet scoop sections are of alclad aluminum alloy and are mounted fore and aft of the oil-coolant radiator, respectively.
Footsteps and handholds
The extreme trailing edge of the left fuselage to the wing fairing has a reinforced rib, thus providing a footstep.
At the left side of the fuselage below the trailing edge of the rearview window, a flush-type spring-loaded door, which opens inward, is provided as a handhold.
Cockpit sealing bulkheads
Two wooden bulkheads are installed in the fuselage.
These prevent any objects dropped within the cockpit from rolling all of the cockpit or radio compartment and fouling any of the surface control cables or sectors, and help prevent drafts from entering the cockpit.
The bulkhead is provided with openings for the warm and cold air ducts, and a cutaway at the center for clearance for the forward elevator cable bellcrank.
The tail section of the fuselage consists of 2 longerons at the bottom and a flat shelf.
A solid bulkhead is located at the detaching point of the forward and the aft section and serves to transfer the side shear from the upper flat shelf to the shelf in the forward section.
The tail section provides for installation of the tail wheel and the horizontal and vertical stabilizers.
The landing gear consists of 2 retractable main gear assemblies with disc-type brakes and 27-inch smooth-contour wheels, installed in the main wings, and a retractable auxiliary tail gear assembly with a 12.5-inch smooth-contour wheel, installed in the tail of the fuselage.
Main Landing Gear
The main landing gear assemblies are supported by the landing gear support castings, which are installed on the forward side of the front spar in each wing at the outboard end of the wheel well.
The support castings are bolted to the front spar of the wing and to the lower and upper skin of the wing in order to dissipate the landing gear thrust into the entire wing structure.
Each gear retracts inboard and into the wing by means of a hydraulically actuated retracting strut mounted on the front spar of each wing inboard of the landing gear support casting. When the landing gear is retracted, the main gear is completely enclosed in the wings
The air-oil system of shock absorption is used in all of the landing gear struts Baffles and a metering pin in the shock strut cushion the shock of a landing.
Hydraulically operated main gear fairing doors are hinged to the castings installed on the center rib of the wing.
The doors (ofter referred to as clamshells) are controlled by hydraulically actuated struts which are mounted on the top skin of the wing. Fairing door locks, incorporated in the landing gear lock rod system, engage the locking lugs on the aft sides of the fairing doors.
When the main gear is retracted, the fairing doors close flush with the lower skin of the wing when the main landing gear is fully extended and when the gear is in the retracted position. The hydraulic system is timed so that the fairing doors open to permit the landing gear to pass as they go up or down.
Controls and warning lights
The mechanical and hydraulic operation of the landing gear is controlled by means of the landing gear control handle on the lower left side of the cockpit.
The undercarriage is raised or lowered by the undercarriage selector lever, located on the port side of the cockpit near the floor. When the full weight of the aeroplane is on the wheels, the undercarriage selector cannot be moved to the UP position and the undercarriage cannot be raised.
To lower the landing gear, pull out the spring- loaded control handle at the lower center side of the control pedestal marked LAND GEAR and push down until it locks. To raise the gear, pull the control handle all the way up until it locks.
On AG664 and aerlier aeroplanes:
On AL958 and subsequent aeroplanes:
The tail wheel is a 12.50 x 4.5 inch high pressure wheel with a split hub and a 12.50 x 4.5 inch channel tread tire and tube are installed on the auxiliary tail gear axle. This static conducting type of tire forms the static ground for the entire plane.
The tail wheel is fully retractable. The tail wheel moves forward and up as it retracts. It is retracted by means of a hydraulic actuated strut controlled by the landing gear control handle in the cockpit.
In the retracted position, the tail gear fairing doors enclose it completely within the fuselage.
When in the down position, it is can be made steerable over a range of 6° either side, with the rudder, or be full-swiveling. The locking lever is on the port side of the seat. With the lever down, the tailwheel is locked in the steerable position. To unlock and render fully castoring, pull out the handle on the end of the lever and twist to secure it, then pull back the lever until it clicks into position. To lock the tailwheel, twist the handle and allow handle and lever to spring back to the locked position.
When taxying, always use the fully castoring position to avoid ruining the tail wheel tyre.
The brakes are Goodyear hydraulic multiple-disc and are installed on each main landing gear.
The brake system consists of two master cylinders, one connected to each brake by means of brake lines. The brake hydraulic system is entirely separate from the general hydraulic system, except that the brake system receives its supply of hydraulic oil from the general hydraulic system reservoir.
Brake Pedals—The brakes are selectively controlled by means of toe pedals incorporated in the rudder control pedal assembly. They are conected by means of a mechanical linkage through the brake master cylinders. The left pedal operates the left brake, and the right pedal operates the right brake. When a toe pedal is depressed, braking pressure is generated in the respective brake cylinder: and when the pedal is released, the braking pressure is released by means of a spring arrangement in the brake cylinder.
Parking brake - A parking brake, controlled by means of the parking brake control handle just below the center of the instrument panel, is incorporated in the brake system. The parking brake is designed to hold the wheels in a locked condition over long periods of time without pressure being maintained on the foot pedals. To park, depress both rudder pedals, pull PARK BRAKE and hold, release pedals, then release PARK BRAKE.
To release the parking brakes, depress both rudder pedals.
The hydraulic system is utilized for the operation of the landing gear, radiator air scoop and wing flaps.
A single high-pressure hydraulic system provides for the simultaneous operation of the main gear and tail wheel, and the selective operation of the wing flaps and radiator air scoop.
As mentioned above, an entirely separate brake system is supplied with oil from a standpipe arrangement in the hydraulic system reservoir. This reserve oil is available for operation of the brakes even though oil for the operation of the remainder of the hydraulic system is lost.
A hand-pump, located to the right of the pilot's seat, makes it possible to operate the hydraulic system when the airplane is on the ground with the engine inoperative, or should the engine pump fail during flight
The following tabulation shows the average normal operating speeds, in seconds, of the various systems during normal flight. In ground operation of the systems, the charted speeds should be adjusted wherever applicable to compensate for air loads imposed upon the units during flight, and the free air temperature should also be taken into consideration, as extremely cold weather will slow down the operations and extreme heat somewhat increase their speeds.
Landing Gear Down 15 to 18 Seconds
Landing Gear Up 12 to 15 Seconds
Wing Flaps Down 11 to 15 Seconds
Wing Flaps Up 11 to 15 Seconds
Radialor Air Scoop Open 11 to 15 Seconds
Radiator Air Scoop Close 11 to 15 Seconds
The total hydraulic system capacity is 3.75 U S. gallons (3.12 Imperial gallons).
All plumbing is of 52SO aluminum alloy tubing except where flexible hoses have been used of necessity. All hydraulic lines have their corresponding
North American part numbers clearly stamped on them and are provided with the color identification band: blue—yellow—blue.
Engine, Propeller & Cowling
As mentioned in point 3, the fuselage is divided into three major sections: the engine mount, the main section and the tail section.
Here we will discuss the engine mount, comprising of the engine, the engine housing, the cowling, the exhaust, carburator and propeller.
The Mustang is powered with an Allison Model V-1710-39, V-type, 12-cilinder, liquid-cooled engine sporting 1,150 bhp. It is to be operated with gasoline of 100 octane number.
The engine is equipped with an integral oil and coolant pump, a Bendix Stromberg PD12K2 carburetor fitted with an idle cut-off device, and the following units:
Automatic boost control
The engine mount consists of two individual Y-shaped, aluminum-alloy box- beam structures, each mounted at two points of attachment to the fire wail and extending forward on its respective side of the engine. The upper points of attachment are at the forward extremities of the upper fuselage longerons, and the lower points are at fittings on the bottom of the fuselage frame structure.
The engine mount has been designed to afford ready access to the engine and accessories for servicing. The engine is cradled between the mount beams, and attached by means of studs to four shock absorbing units encased in the mount.
For engine installation the mounting may be attached to a fixed structure and the engine and accessories installed before the complete power plant is installed at the fire wall.
The engine cowling consists of a nose ring and five completely removable panels. The engine nose ring is rigidly bolted to the forward end of the engine mount and contains fittings to which the forward end of the engine cowl formers are bolted.
The coolant tank and the coolant tank armor plate are mounted on the inside of the nose ring, and access to the coolant tank filler plug is gained through a hinged door containing two Dzus fasteners, located on the upper left side of the nose ring. A Dzus-fastened door is also contained in the right side of the nose ring to provide access to the propeller constant speed control brushes and the propeller spinner attaching bolts.
The windshield defroster tubes pass along the exhaust stacks and are connected to two small openings, in the bottom of the nose ring, which supply the inlet air for the defrosting system. The upper half of the engine cowling is a single panel with the carburator air scoop, containing three sections riveted together.
The large center section is of 24ST Alclad aluminum alloy, so designed and constructed that the carburetor air scoop is an integral part of it. The two other sections which are placed in the area just above the exhaust stacks, are narrow strips of stainless steel for resisting heat.
The power plant accessory compartment cowling consists of four separate panels of 24ST Alclad aluminum alloy. The upper panel contains a Dzus-fastened door for access to the oil tank filler neck, and also three levers located in the aft right corner for ventilation of the accessory compartment. The lower panel is fitted with an opening containing a bushing reinforced on the inside for insertion and support of the engine starting crank.
The engine exhaust is discharged from the 2 exhaust ports in each cylinder through an individual exhaust stack for each cylinder. The design of the exhaust stacks incorporates a combination of flame dampening and jet propulsion features. The stacks are constructed of corrosion- and heat-resisting stainless steel.
The carburator mixes the air with fuel for the engine.
The Mustang is equipped with a type PD-12K2 Bendix Stromberg injection carburetor, which differs from previous types in that it does not have a vented float chamber, but instead it has a closed fuel system from fuel pump to discharge nozzle. The fuel is delivered by the engine fuel pump at about 14 pounds per square inch pressure to the regulator and control units. There it is metered according to the mass air flow rate, as registered by the venturi tube and automatic mixture control unit. The fuel is then forced to the spray nozzles, which spray the charge evenly across the face of the supercharger. Fuel is prevented from leaking into the engine by the spring-controlled discharge nozzle, which is closed when the nozzle fuel pressure is less than 4 pounds per square inch. The fuel is metered through fixed orifices according to venturi suction.
(a) AUTOMATIC MANIFOLD PRESSURE REGULATOR - This engine is equipped with a Delco Remy automatic manifold pressure regulator, type AAFA-2. This regulator is a mechanical device mounted on the left side of the accessory case next to the carburetor and interconnected to the carburetor throttle for the purpose of maintaining, within desirable limits, a selected manifold pressure, independent of altitude, up to the service ceiling of the engine. After the pilot moves the throttle control to obtain the desired manifold pressure, the pressure regulator will automatically compensate for the differences in air density at various altitudes by gradually opening the throttle as the altitude is increased and smoothly closing the carburetor throttle during descent, thus maintaining the required manifold pressure during climbing and diving. This device, therefore, relieves the pilot from the necessity of making carburetor throttle corrections to maintain required manifold pressure during ascent or descent.
(b) CARBURATOR AIR SCOOP AND HEATING DUCT - The carburetor air scoop consists of an air intake duct built integral with the top engine cowling and an elbow duct mounted by means of a flexible joint to the carburetor intake There are two types of air intake ducts, either of which may be installed on the airplane. One, a lightweight duct, supplies only rammed unfiltered air, the other is equipped with a retractable filter which can be operated in flight by the pilot. In case of the second type, the filter control is located on the right side of the instrument panel. To obtain filtered unrammed air, the control handle must be pulled. To obtain unfiltered rammed air it must be pushed.
A manually controlled alternative warm air intake is provided. There two carburator air control handles located on the left side of the instrument panel. Normally the control will be kept in the locked cold position, i.e. control in and handle twisted so thath the arrow on the handle points to the left. The hot air intake should only be used under icing conditions. To obtain hot air the push-pull handle needs to be twisted to that the arrow points to the right.
The engine is equipped with a Curtiss three-bladed, 10-foot 9-inch diameter hydro electric, constant-speed propeller. A reversible eletric motor mounted in the propeller hub serves to control the propeller blade angles.
The propeller governor control lever is located on the control quadrant, and the propeller SELECTOR SWITCH is on the left side of pilot's switch panel. By moving the selector switch, the propeller may be controlled for optional automatic constant speed operation, fixed pitch, or manual selection. The manual control positions of the switch lever are marked DEC RPM and INC RPM. Contact is maintained only while the switch is held in these respective positions: when released, the switch returns to FIXED PITCH. Thus the manual control is a means by which propeller pitch may be adjusted to obtain any desired RPM with precision. A spring-loaded guard moves the switch to AUTO CONSTANT SPEED when swung upward A circuit breaker at the right of the selector switch is used to cut ofl the power in case of overload.
Engine start procedure:
The units: the fuel system, including the main system and the auxiliary system, consists essentially of the following units:
Main fuel tanks (2)
One in each wing
Selective Sump Valves (2)
Between the main tanks in the centersection of the wing
Right side of the firewall, bottom
Left Side of the firewall, bottom
Selector Valves (2)
Inside of right and left wheel recesses
Aft end of the engine
Lower aft end of the engine
Ferrying tanks (2)
Bottom of the wings, outboard
Combat tanks (2)
Bottom of the wings, outboard
There are two 90-gallon, pressure molded, fuel tanks of self-sealing type installed in the wings of the airplane. They are made by the Firestone Tire and Rubber Company.
The reserve fuel supply is a portion of the contents of the left tank.
Capacities are as follows:
Right main tank
90 US gallons (75 imperial gallons)
Left main tank
59 US gallons (49.2 imperial gallons)
31 US gallons (25.8 imperial gallons)
180 US gallons (150 imperial gallons)
Note: one set of two auxiliary fuel cells, 29 US gallon (24.1 imperial gallon) capacity each, is supplied as loose equipment with each airplane and may be installed in lieu of the guns and ammunition in the wings, thereby adding 58 US gallons (48.3 imperial gallons) capacity to the airplane.
Additional tanks can comprise of:
Ferrying tanks (2) - 90 US gallons (75 imperial gallons)
Combat tanks (2) - 75 US gallons (62.5 imperial gallons)
The droppable ferrying tanks are constructed of wood and have a fuel capacity of 150 US gallons (125 Imperial gallons) each. When carried, they are installed on the bomb racks by means of two shackle fittings. Four sway brace fittings secure the tank. The tank fuel line is connected to the wing outlet by a rubber hose and a straight nipple which is installed in the underside of the wing forward of the bomb rack. Access to the fuel line within the tank is gained by the removal of the access door, which also contains the filler cap. A vent line extends along the top of the tank from the front to the rear. The filler cap is at the front and top of the tank, and the drain plug is on the bottom of the tank.
The droppable combat tanks may be installed on the bomb racks when neither ferrying tanks nor bombs are being carried. They are constructed of thin metal template interlined with a pressed rubber covering, and contain a series of baffles inside. The fuel flows through a strainer, which also acts as a drain plug, located at the bottom of the tank. A vent line extends from the top of the tank to the aft end.
The engine is supplied with fuel from the two main self-sealing tanks in the wings and from the auxiliary tanks when they are installed.
The regular fuel flow is from the main tanks, through the selective sump valves to the selector valve, through the fuel strainer and booster pump, and on to the engine fuel pump and carburetor. When auxiliary tanks are used, the fuel from them passes through the auxiliary system selector valve and on to the main fuel lines.
The auxiliary tanks consist of either droppable combat or ferrying tanks, one mounted beneath each bomb rack. The main fuel lines are of the self-sealing type, and aluminum tube lining is used at critical bends. The tanks are not interconnected, and it is necessary to switch from one tank to the other to provide smooth operation of the engine.
Sufficient feed to the engine during steep climbs or dives is ensured by 2 outlet lines, 1 at the forward end and 1 at the aft end of each tank, interconnected by a selective sump ball- and-socket valve to a single line. Additional facilities for furnishing the engine with sufficient fuel when the fuel level becomes low are the bulkheads with Happer valves, located at the inboard end of each tank, which form a sump chamber over the fuel outlet, and the booster pump installation.
The carburetor is of the fuel injection type containing an idle cutoff device, and is equipped with a vapor line that extends to the left main fuel tank.
To operate the fuel system, proceed as follows:
a. Set the main fuel tank selector valve in the RIGHT or LEFT position.
b. Set the booster pump switch in the ON position and then start the engine.
c. Switch the selector valves of the main and auxiliary systems to all positions to determine that the systems are functioning properly.
The fuel cock on the cockpit floor had three positions: RIGHT (forward), LEFT (aft) and OFF (starboard).
Note: if Mod. No.375 is NOT incorporated, the fuel cock has four positions: RIGHT (forward), LEFT (port), RESERVE (aft) and OFF (starboard). LEFT draws fuel from a stackpipe in the port tanks, and leaves 26 gallons in resere. RESERVE draws fuel from the bottom of the port tank. RIGHT draws fuel from the bottom of the right tank.
The electric booster pump for the fuel system is a Type G 10, Model TFD-10,100 manufactured by the Thompson Products Company of Ohio.
The control switch for the booster pump is on the right side of the switch panel below the instrument panel. The pump assembly consists of two units, a No. A-7025 motor and a Type TFD-2100 fuel pump. The relief valve, which is housed in a separate body, may be mounted in reverse position on the pump to permit change of rotation where this may be necessary. The booster pump may be used for either the main fuel system or the auxiliary fuel system by adjustment of the selector valve controls.
If mod.No.344 has been carried out, the fuel booster pump is brought into action when the propeller is in the FINE PITCH position. There is also a manual switch beside the propeller speed control lever wired in parallel with the propeller switch, so that the booster pump may be switched ON if it is required when the engine pump is not running or at high altitude. Normally this switch is kept OFF and the booster pump is automatically controlled by the propeller speed control.
An engine-driven fuel pump Type G9. is mounted directly on the engine at the aft end. When the engine is being started, this pump is assisted by the booster pump
Two fuel selector valves, one located in each wheel recess, provide for control of the main fuel system and the auxiliary fuel system. The valves are manually operated by control handles located side by side on the cockpit floor, directly underneath the switch panel.
Engine Primer System
An engine primer pump and operating handle are installed on the subpanel at the lower right side of the instrument panel. When priming operations are completed, the handle must be pushed in and turned clockwise to the OFF position.
The distributor valve is located forward of the carburetor on top of the engine. From the distributor, four 1/16-inch lines run to the forward and aft ends of the intake manifolds.
To operate the engine primer, proceed as follows:
a. Push in on the operating handle and rotate counterclockwise to unlock.
b. Pull out and then push in on the handle. Prime the engine in this way: 3 strokes when cold, and 1 stroke when warm.
WARNING: Caution must be used when priming the engine, as overpriming constitutes a fire hazard.
c. When priming is complete, push the handle fully forward and rotate clockwise to lock.
A propane primer system is provided for priming the engine in extremely low temperatures. The plug for outside attachment is accessible through the ground heating door of the engine accessory compartment cowling.
The carburetor is a Stromberg Type PD-12K6 and is mounted on the aft end of the engine; refer to Section 6.6 for more detailed information.
The oil system consists of the following:
Forward side of firewall at the top
Within coolant radiator at bottom of fuselage, aft of cockpit
Lower aft end of engine accessory case
Cuno oil filter
On right-hand side of engine accessory case
Temperature & Pressure Indicators
Lower right-hand side of instrument panel
The oil flows from the bottom of the tank to the oil pump, and is then delivered to the Cuno oil filter through a spring-loaded check valve, which prevents oil flow from the tank when the engine is stopped.
From the filter outlet, oil is distributed to the moving parts of the engine. When the airplane is in normal position, all oil drains to the oil pan and is scavenged by the main scavenger pump from the accessory end of the oil pan. From the scavenger pump outlet, the oil flows back to the oil tank either directly through a by-pass valve, or on through the oil radiator and then back to the tank, depending on the oil temperature. The oil dilution system is controlled by an electrically operated solenoid on the firewall. The fuel intake for the oil dilution system is at the carburetor, and fuel is introduced into the oil system at the Y drain.
It is designed to permit the airplane to assume any attitude when the tank is full, and to feed adequatly in a vertical climb or dive when the tank is only one-fourth full.
The oil tank is a hopper-type tank constructed of aluminum alloy. With this type of tank, it is necessary to drain the engine lubricating oil at engine change only, unless failure of an engine part makes it necessary to change oil before that time.
It has a capacity of 10.1 gallons, plus an air space of 1.2 gallons.
A honeycomb-type cylindrical oil radiator is located in the top center of the coolant radiator, and the complete oil radiator assembly, including the bypass, surge, and thermostatic control valves mounted on it, can be removed from the outer coolant section as an individual unit.
The cooling system consists of the following:
Bottom left side accessory section
Inside engine nose ring at the top
Bottom of the fuselage, aft of cockpit between air scoop inlet and outlet
Instrument panel, lower right-hand side
A solution of ethylene glycol with a corrosion inhibitor is the coolant medium. The system requires 19 U.S. gallons (16 Imperial gallons) to fill it. The liquid in the coolant system flows in this pattern: from the coolant pump into the engine at the bottom: through the engine and out the top: aft to the coolant radiator at the top, and through the radiator to the outlet at the bottom: then back again to the coolant pump. The coolant tank is interconnected with the pump to replenish the coolant supply in the system. The radiator is mounted in the center of an air scoop assembly designed to concentrate a flow of air through the radiator, and also to control the engine oil and coolant temperatures.
The centrifugal-type coolant pump is located on the bottom of the accessory’ case. It is manufactured by the Allison Engine Company and is furnished with the engine.
The tank is tubular and is curved to conform to the contour of the engine cowling. The interior of the tank is completely void of structures, baffles, etc. The filler flange is so positioned in the tank that, when the tank is filled to overflowing, one gallon of coolant liquid is in the tank and the remaining space serves for expansion.
The coolant radiator is of the honeycomb type with a brass outer shell. The opening in the top provides for the insertion of the oil radiator. The core consists of a number of copper tubes grouped together in a form somewhat like the letter U when viewed from either end. A drain plug is provided on the bottom of the radiator. The coolant liquid seeps down between the round cooling copper tubes, the hexagonal ends of the tube being sealed with solder.
Radiator Air Scoop
The forward and rear end of the scoop are movable and are adjusted by hydraulic action controlled from the cockpit.
The radiator air scoop selector is on the aft end of the control pedestal to the left of the pilot's seat. It clicks into the OPEN, LOCK or SHUT positions. To partially open the radiator scoop, put selector to OPEN, then return it to LOCK when the desired position is indicated on the mechanical radiator indicator (beside the flaps position indicator).
On AG664 and earlier aircraft, the hydraulic control knob must be pushed in before the scoop can be operated.
The opening or closing of the scoop regulates the amount of air flowing through the radiator, which in turn regulates the temperature of the engine oil and coolant in the radiator.
Air scoop deflector: Fitted only on AG664 and earlier aircraft). To lower the air scoop deflector, pull the latch beside the radiator scoop seleotor sideways and move the radiator scoop seleotor fully forward. The hydraulic control knob mist be IN. The air scoop deflector should be lowered when starting the engine, diving, or during long glides, or if oil coring occurs.
The instruments may be divided into these four general categories: the vacuum instruments, the pitot static instruments, the engine instruments, and the miscellaneous instruments.
All instruments, with the exception of the carburetor temperature indicator, the hydraulic pressure gage, and the fuel level gages, are mounted on the instrument panel, which is illuminated by fluorescent lights mounted on each side of the cockpit and controlled from nearby switch panels.
For the various instruments, the location of those instruments on the instrument panel photo, are indicated between brackets.