1. Introduction.

...........Handling trials have been carried out on Mustang A.G.351 at the normal load and at a load giving the extended aft c.g. Short handling flights were also made at the forward c.g. limit on A.G.383 fitted with a heavier duralumin propeller as opposed to the hollow steel bladed Curtis propeller fitted on A.G.351. Some dive tests were also made for convenience on another aircraft A.L.973. This report is based on the experience gained by flying the above aircraft between January and July 1942.

2. Description of aeroplane (A.G.351)

...........The aeroplane is a low wing high performance single seat fighter type, with a low drag section straight taper wing and squared wing and tail plane tips. The bottom of the fuselage aft of the trailing edge fairing bulges to form the fairing for the radiator and oil cooler unit. Hydraulically operated intake scoop and exit duct flap are fitted to the radiator housing. A spoiler flap is incorporated under the fuselage in front of the radiator intake to cut off the air flow through the radiator and oil cooler in dives.

...........The aircraft is fitted with fully retracting undercarriage including the tail wheel. Doors completely enclose the wheels and legs, when they are retracted.

...........The armament consisted of 2 x 0.5" guns protruding from the lower engine cowling, firing through the propeller disc, and 4 x 0.3" and 2 x 0.5" guns in the wings, firing clear of the propeller disc. The wing gun ports were sealed with fabric during the tests. A bead sight was fitted in front of the windscreen which has a bullet-proof laminated transparent plate fitted on the inside.

...........The aircraft is powered with an Allison V1710 F-3-R engine, driving a 10'-6" diameter 3 blade Curtiss electric propeller. The fuel capacity is 140 Imperial gallons which is contained in the wings in self sealing tanks.

...........The pressed aluminum oil tank is situated between the engine and fireproof bulkhead. It is provided with a hopper for accelerated oil warming. Flapper valves in the cross baffles and a swivelling sump feeder are designed to provide the engine with a sufficient supply of oil no matter what attitude the aircraft adopts. The normal capacity of the tank is 6 1/4 Imperial gallons.

...........The wing flaps on this aircraft are the type where the whole trailing edge of the wings inboard of the aileron moves down.

...........All control surfaces are fabric covered with the exception of the ailerons which are all metal. They are all provided with trimming tabs which are adjustable in flight.

...........An aerial mast was fitted behind the cockpit hood. The W/T aerial stretched from the mast to the fin tip and the I.F.F. aerials from the tail plane tips to either side of the fuselage.

...........A Kollsman type pressure head was fitted on the underside of the starboard wing.

...........Landing lights are situated in the leading edge of each wing and the usual navigation lights are fitted on both top and under surfaces of the wings and the trailing edge of the rudder.

3. Cockpit Layout.

....3.1 Ease of entry and comfort. Entry to the cockpit is effected by hauling oneself up on to the port wing root fairing with the help of the hand hold recessed in the fuselage. No intermediate step is fitted and no non-slip walkway is provided on the wing fairing. In wet weather climbing onto the wing is rather awkward especially when wearing a parachute. Once on the wing however, entry is effected easily as the hood and port side panel fold up and down respectively, leaving a fairly large area for entry and a low ledge to step over.

...........Cockpit heat is available from a hot air entry duct behind the radiator unit, and can be controlled by a butterfly throttle where the warm air enters the cockpit on the bottom right of the seat. Cold air is available from a duct in front of the radiator whence it enters the cockpit at the base of the control column via a "butterfly" control on the left of the seat. Two louvers situated on either side of the cockpit behind the pilot's head provide exits for the ventilating air.

...........At low altitudes, even with the hot air shut off completely, the cockpit is uncomfortably warm. This is due to hot air coming from the radiator unit, as the top of the radiator shell is exposed to the interior of the fuselage. Air leaking through the fairing duct and various holes for the coolant pipes, combined with the convection currents from the radiator, sweep upwards striking the pilot in the back of the neck before passing out through the ventilation louvers. It is suggested that the leaks be sealed and a false fuselage floor be fitted over the portion of the radiator shell exposed to the interior of the fuselage. This would also provide protection from coolant fumes should the radiator be damaged in combat.

...........The head room provided is inadequate. Even with the seat fully down, and average sized pilot feels very cramped. No undue noise or vibration was experienced under any conditions of flight.

....3.2 View. The view for a single engine fighter is good, especially to the front over either side of the fuselage. This is due to the narrowness of the nose compared with other fighters such as the Spitfire. No forward clear view panels are fitted but each side panel is fitted with a sliding window.

...........A rear view mirror is mounted on the inside of the hood but the resulting view to the rear is very poor.

....3.3 Controls.

.....(a) Flying. The control column is of the plain stick type with a straight rubber grip. It is considered rather too long for comfort in prolonged flying, and should be shortened by 3 to 4 inches.

...........The control column and rudder pedals can be locked by inserting a spring loaded plunger through two fixed locating brackets at the base of the control column. No "nuisance bar" is fitted but the control column is locked right forward in such a position as to render any attempt at take-off highly improbable.

...........The rudder pedals are of the individual pendulum type with toe operated brake pedals. The control operates satisfactorily and fore and aft adjustment can be made to five different positions giving adequate range for normal sized pilots.

...........The elevator trimming tab control consist of a 6 inch diameter plain rimmed wheel with a large notch cut in the rim, which indicates the neutral position when at the top. An indicator needle is fitted giving divisions up and down. The control falls quite readily to hand being situated by the pilot's left knee on the side of the cockpit.

...........The rudder and aileron trimmer controls consist of a large black moulded knob fitted with indicator pointers giving divisons right and left. They are conveniently mounted on a ledge on the left hand side. All trimmer controls are mounted in the plane in which they respectively affect the aircraft.

.....(b) Undercarriage, flaps and radiator. A hydraulic pressure control knob is situated on the left of the dashboard. When the undercarriage, flaps or radiator shutters are required to operate, the hydraulic pressure control knob is pushed in and when the appropriate selector lever is moved to the required position, the operation commences. The undercarriage selector lever is on the left well forward near the floor of the cockpit and is very awkward to reach and operate in comfort. The lever grip is spring loaded and has to be pulled up before it can be moved from the locked positions. Three positons "UP", "DOWN" and "EMERGENCY" are provided. The emergency position is only used when the underdarriage has not locked correctly in the "down" position. When the lever is placed in this position the locking pins are mechanically forced into place. If the engine driven hydraulic pump fails the system may be operated by the hand pump situated to the rear on the right hand side of the seat. If the complete hydraulic system fails, the undercarriage may be lowered by pulling the emergency knob on the left side of the dashboard, casuing the hydraulic fluid to by-pass and allowing the undercarriage to come down under its own weight.

...........The wing flap control is the yellow handled control lever situated on the left near the bottom of the cockpit panelling. The up and down positions of the lever select the respective flap positions. A centre lock position is provided for locking the flaps in an intermediate position.

...........The radiator scoop and exit duct flaps are controlled simultaneously by movement of the selected lever mounted just forward of the wing flap control. The deflector for the radiator is operated by the extreme forward movement of the scoop control. A safety catch on the side of the quadrant has to be pulled out before this forward movement is possible.

...........The flap and radiator controls fall quite readily to hand and their operation is considered satisfactory.

...........Undercarriage, wing flap and radiator shutter positions are shown by mechanical indicators sliding in calibrated grooves on the left side of the cockpit. The wing flap and radiator shutter indicators are positioned well forward and are mounted flush with the cockpit panelling making it necessary for the pilot to lean forward to the right the read them accurately, but it is considered that their positions are adequate.

...........The usual red and green indicator lights and warning horn are fitted for the undercarriage system. The lights can be dimmed for night flying by a rheostat control in the centre of the instrument. See para 3.8.

...........The tail wheel is steerable to the extent of the rudder pedal movement and can be locked for take-off and landing by twisting the red handled control lever on the left of the seat and allowing it to telescope in.

.....(c) Engine. Throttle and mixture controls are positioned satisfactorily on the top left-hand side of the cockpit panelling. The propeller pitch control lever is just below. All three controls are fitted with adjustable friction devices which prevent creeping.

...........The propeller pitch may be changed by putting the selector switch into AUTOMATIC and operating the control lever, or manually by using the selector switch in the MANUAL INCREASE R.P.M. or MANUAL DECREASE R.P.M. positions. The propeller pitch control selector, ignition, electric starter and oil dilution switches are conveniently situated on the lower switch panel below the instrument panel. The engine primer pump is fitted on the right of the instrument board.

.....(d) Miscellaneous. The fuel cock is mounted within easy reach on a pedestal on the cockpit floor just forward to the left of the control column. The cock has four distincly marked positions OFF, RESERVE (26 Imperial gallons), STARBOARD (70 Imperial gallons) and PORT (44 Imperial gallons). Port and Starboard fuel gauges are positioned on the cockpit floor either side of the pilot's legs.

...........A windscreen defroster control is situated on the upper left of the instrument panel which permits hot air to pass between the two layers comprising the windscreen when the knob is pulled out.

....3.4 Seat. The seat is of welded aluminum alloy constuction and is designed to take the normal seat type parachute. The seat is adjustable for height by releasing the handle on the right hand side of the seat. A Sutton Harness is fitted with a release catch control lever on the left of the seat permitting the pilot to lean well forward when necessary. The back of the seat is provided with a leather cushion.

....3.5 Brakes. Toe cap type brake controls are fitted to the rudder pedals. These were found to operate smoothly and satisfactorily under all conditions. A parking brake control is fitted centrally below the instrument panel. The brakes will hold the aeroplane while the engine is being run at full throttle on the ground.

....3.6 Instruments. The lay-out of flying and engine instruments on the large central panel is good and all instuments acan be clearly seen. The usual type of blind flying instuments and engine instruments are fitted. No undue instrument vibration is experienced in any condition of flight. The navigation compass is mounted on a small pedestal to the right of the control column.

....3.7 Illumination. Brief night flying trials have been made on this aeroplane. The instrument and cockpit illumination was found to be very satisfactory except for bad reflection in the transparent side panels. The instruments are illuminated separately by indirect lighting, and two swivel lamps mounted on either side of fuselage panelling provide light for the cockpit. All the lighting equipment is provided with adjustable rheostats to control the intensity, but not to such an extent as to prevent glare from the reflection in the side panels.

...........The landing light was not used, so no comments can be made.

....3.8 Emergency exits. An emergency exit handle to jettison the hood assembly consists of a plainly marked red lever mounted on the cockpit coaming to the right of the instrument panel. An upward pressure must be applied to the hood before it becomes free. A strong point is fitted in the form of a robust pylon at the rear of the seat to prevent the canopy collapsing if the aircraft should over-turn on the ground. When inverted on the ground, it should be possible to push out the hinged port window and effect an exit.

4. Handling and flying qualities.

....4.1 Loading of aircraft.

...........The above centre of gravity positions are with the undercarriage down. Retracting the undercarriage moves the centre of gravity forward 0.3" at the normal load.

...........A.& A.E.E. limits for Mustang A.G.351 fitted with hollow steel propeller are 2.3" forward and 2.7" aft of the datum including the 1% S.M.C. aft extension. The limits for the aircraft fitted with the duralumin bladed propeller are 2.8" forward and 2.2" aft of the datum, including aft extension. These limits are those obtainable by dissipation of load.

....4.2 Ground handling. Due to the comparitively good view forward to either side, taxying is particularly easy with the steerable tail wheel. The brakes operate smoothly and even at the forward limit there is no tendency for the tail to raise inadvertently.

....4.3 Take-off. The take-off is easy and straightforward. Any tendency to swing can be readily checked by use of rudder alone. To obtain the shortest run the tail should be raised early by use of elevator and the aircraft pulled off the ground. The best flap setting for take-off was found to be 15 degrees indicated. At flap settings greater than this, there is a strong tendency to drop the left wing; full aileron is needed to check this at 30 deg. flap. The best elevator trimmer setting is between 0 and +5 divisions according to the amount of flap used i.e. with increase of flap the aircraft tends to become more nose heavy. These trimmer settings can be used at all loadings. Take-off speed with 15 deg. flap is 80 m.p.h. A.S.I.

...........Direct cross wind take-offs were made at the normal load in winds up to 30 m.p.h. They can be easily effected from either side. The aircraft behaves very well, there being no need to use aileron during the run. The tendency to swing down wind can be easily checked with rudder and the aircraft always feels under perfect control. With the wind on the starboard side the left wing drops slightly as the aircraft leaves the ground, but this can easily be checked by aileron and is not considered dangerous. No trouble is experienced with the tail wheel free, but it is recommended that the tail wheel be locked off for take-off, since any swing that should occur is therby reduced.

...........At the extended aft c.g. limit the tail is a little heavier and takes slightly longer to raise, but the same trimmer settings can be used and the take-off is striaghtforward.

...........Take-off at night down a flare path is normal and straightforward.

....4.4 Initial Climb. The aircraft climbs away steadily. There is no violent change of trim at any loading when the undercarriage and flaps are raised. The flaps can be safely raised when a height of 500 feet is reached with an indicated airspeed in excess of 120 m.p.h. A,S,I. The aircraft becomes slightly tail heavy on raising the flaps but there is no tendency to sink. The best initial climbing speed is 160-170 m.p.h. A.S.I. with undercarriage and flaps raised.

....4.5 Controls. All controls operate satisfactorily in all conditions of flight. There is adequate trimmer range at all loadings. The controls have been used in the dive up to speeds of 500 m.p.h. A.S.I. and although the forces on the control column and rudder pedals are large for small movement, all controls are usable. At the stall, the controls are effective for large movements.

...........Special attention was paid to the effectiveness of the ailerons and rate of roll tests were carried out at 200, 300 and 400 m.p.h. A.S.I. No stick force indicator was fitted but the force on the control column is light enough for full aileron to be applied without undue effort. At 200 m.p.h. A.S.I., the aileron control was very light but the time to roll through 90 degrees did not appear unduly fast, due to the aircraft lagging considerably behind after applying full aileron as rapidly as possible. Times for a 90 deg. roll were consistently between 1.8 and 2 seconds. At 300 m.p.h. A.S.I. the force on the control column still remained very light and the times to roll through 90 deg. were indentical. At 400 m.p.h. A.S.I. the force on the control column increased appreciably, though it was still possible to apply full aileron fairly rapidly without excessive force. Times for a 90 degree bank averaged 2.3 seconds.

...........All rate of roll tests were done at the normal load and were timed from 45 deg. to port to 45 deg. to starboard, using the left hand to push the control column. It is estimated that full aileron can be applied at 400 m.p.h. with a force of the order of 20 lb.

...........The ailerons increase in heaviness as the speed increases, but they are still lightat speeds up to 400 m.p.h. A.S.I. The rate of roll for full aileron is definately much faster than on any other present day day fighter so far tested at this establishment.

....4.6 Stability. For all positions of the centre of gravity the aircraft is stable laterally and directionally throughout the speed range, flaps and undercarriage up and down. At the aft limit, it is stable longitudinally at normal flying speeds engine on, decreasing to neutrally stable at climbing speeds. On the glide, flaps and undercarriage up, it is neutrally stable and with flaps aand undercarriage down, it is stable. Generally speaking, the stability is very satisfactory at this limit, being sufficiently unstable to allow pleasant manoeuvring qualities.

...........Forward movement of the centre of gravity has little effect; the aircraft naturally becomes more positively stable and feels rather heavier longitudinally.

....4.7 Aerobatics. All aerobatics have been carried out at the different loadings on this aircraft and were found to be normal and satisfactory. General manoeuvrability is improved by movement of the centre of gravity aft. At the aft limit, the force on the control column in a tight turn is reduced to almost zero, but there is no tendency to tighten up in the turn.

....4.8 Characteristics at the stall. Tests 1,2,3 and 4 of A.D.M.293 were done at the extended aft limit as this is the worst condition in which the aircraft can be flown in this respect. At this loading (8600 lb. C.G. 2.7" aft of the datum), the stalling speeds are 92 and 80 m.p.h A.S.I. with flaps and undercarriage up and down respectively.