|1. According to Air Ministry instructions, and A.D.G.B. letter reference ADGB/S.32179/Air Trg. Dated 28th December 1943, Tactical trials have been completed on the Mustang III. Aircraft No. FZ.107 was delivered on 26.12.43, and was checked and weighted as for operational load (total 10,100lbs). For descriptive purposes chief comparisons have been made with Spitfire IX No. BS.552 (clipped wings and a fairly old aircraft), Spitfire IX No. JL.359, normal wings, fitted with S.U. pump carburetor. Brief comparative trials were carried out against Tempest V. No. JN.737 Spitfire XIV No. RB.141, Focke Wulf 190 No. PM.679 and Me.109G No. RN.228.
2. The Mustang III is a high altitude long-range single seater fighter, armed with four .5” Browning’s in the wings. It is fitted with a V-1650-3 engine (i.e. Packard built Rolls Royce Merlin 61 type), of approximately 1550h.p. It can carry two long-range tanks or two 500lbs. bombs under the wings. In appearance it differs from the Mustang 1 in that it has a different type of engine, four blade airscrew, air intake immediately under the airscrew hub, a deeper fuselage behind the wings housing all the radiators and oil coolers, and a slightly larger fin and rudder. It is a very clean looking aeroplane.
|(i)||The only undercarriage-warning device is a red light by the gun site, which lights when the wheels are unlocked. (There is no light when the wheels are locked up or down.)|
|(ii)||The cockpit, and in particular the instruments, are of American design and consequently seem oddly placed to a British pilot.|
|(iii)||When the engine is started and the mixture lever placed in “Normal”, the locking unit must be tightened, otherwise the pitch control may creep back on take off.|
|(iv)||The tail wheel only becomes castoring when the stick is pushed right forward.|
|(v)||It should be impossible to retract the undercarriage when the weight of the aircraft is on the wheels.|
|(vi)||There are three trimming wheels for all control surfaces.|
|(vii)||The flap angle is pre-selected by the control lever in the cockpit. There is a safety stop, which need only be used when carrying the 120-gallon long-range tanks (i.e. does not apply when carrying normal 62.5 gallon long-range tanks). This is to prevent lowering the flaps more than 30 deg.|
|4. The control column is well placed and of the stick variety. It is pivoted in both directions at its base.
5. No “misting up” was encountered during the trials, including flying at and diving from heights up to 35,000 feet.
6. The Mustang III is very similar to fly and land as the Mustang 1. It is therefore delightfully easy to handle. It is as easy to fly as a Spitfire IX with the exception that the rudder is needed whenever changing bank (in order to prevent skid, and to prevent the sight from swinging off). This soon becomes automatic. The engine feels very smooth.
|(a)||The rudder is heavier. It is far more effective as only a small amount of re-trimming is necessary at high speeds (over 400mph I.A.S.) to keep the aircraft straight. There is no lateral wander.|
|(b)||The ailerons feel lighter, especially over small movements and in general flying. There appears, however, to be a cushioning effect when full aileron is applied. This is because considerably more stick force is necessary when a quick change of bank is desired.|
|(c)||The elevators are considerably heavier. They are not tiring, partly because the change of trim with speed is less.|
8. Because the aircraft is clean, one would expect station keeping to be difficult, but engine response is so steady that formation flying is very easy.
11. Apart from certain cockpit lighting troubles listed below, the take off and landing is also quite straightforward. Use of the floodlight is recommended rather than an airfield floodlight, as considerable cockpit dazzle results when using the latter. To prevent exhaust glare on landing, an engine-assisted approach right to the ground is recommended. With a small modification, blinkers could be fitted to the aircraft where a dusk or night landing is anticipated. It is considered that the disadvantage that would be suffered in day combat, would outweigh this luxury.
|(a)||Undercarriage warning light is lethal. Unless the British type instrument is fitted, this light must be covered over.|
|(b)||The cockpit lighting when suitably manipulated is adequate|
12. Because the Mustang III increases speed so rapidly in the dive, it is not difficult to enter compressibility range at high altitudes (approaching the speed of sound). This can only be done in a dive. The maximum permissible airspeeds at various heights are: -
|13. The following is a summary of the R.A.E’s instructions (Report No. Aero.1906). Should the speeds at height be exceeded by any type of aircraft. In the dive, the nose may suddenly tend to drop. On no account must the trimming wheel be used to prevent it doing so, but only backward pressure on the stick. When the aircraft has reached a lower altitude where the speed of sound is greater, the aircraft will come out of the compressibility range and behave normally, being pulled out of the dive. Had the trimming wheel been used to prevent the nose dropping when in the compressibility range, there would have been a very sudden nose up tendency on coming out of the compressibility range. The result of such a sudden change of trim is liable to cause structural failure.
14. A very close comparison can be made because the engines are of very similar design and capacity. The tactical differences are caused chiefly by the fact that the Mustang III is a much cleaner aircraft, is slightly heavier, and has a higher wing loading than the Spitfire IX (43.8lbs. per sq.ft of the Mustang III. against 31 lbs. Per sq.ft)
16. The fuel consumption at similar boost and rev settings is approximately the same for the two aircraft, but the Mustang is approximately 20 mph faster in level flight. Therefore if the ranges are compared directly according to the fuel capacities of the two aircraft when the long-range tanks are fitted, the Mustang will still have something in hand.
Rate of Roll
Sighting View and Firepower
Rate of Roll
Rate of Roll
Rate of Roll
Rate of Roll
Rate of Roll
|First re-arm -||7½ mins.|
|Second re-arm -||7½ mins.|
|The capacity of the tanks is :-|
|Inboard guns -||350 rounds each.|
|Outboard guns -||280 rounds each.|
|Cine-gun Installation and Harmonization
62. The G.S.A.P. Cine Camera with 3 inch lens is fitted and was harmonized ¼" from the top. No difficulties were encountered.
69. The rammed and unrammed air control lever in the cockpit of the Mustang III No.FZ.107 was inclined to creep back half way between settings during flight. This caused the pilot to be unable to produce the required amount of maximum boost and increased petrol consumption. Much useless flying was carried out before the effects were noticed. For use "at home" it is therefore suggested that for squadron aircraft the lever should be wired in the "Ram-air" position with copper wire.
70. The Mustang III is a delightful and easy aircraft to fly.
71. Its advantages over the Spitfire IX lie in a considerably greater range and greater all round speed. It can outstrip the FW.190 in a dive, followed if desired by a shallow climb. Its only serious drawback is a slightly less rate of climb than the Spitfire IX, particularly at height.
72. A pilot needs to understand the effect of compressibility speeds. Practices should not be attempted.
1. Pasting –lbs of boost readings on to the face of the boost gauge for ease of reading for British pilots, as below.
|BOOST PRESSURE CONVERSION TABLE|
|2. Wire-up the air control lever in the cockpit. (Para.69)
3. For night flying, cover over the Undercarriage Warning Light. (Para 11a)
|8th March 1944.||Commanding, A.F.D.U.|