Handling trials were done at a total weight of 5332 lb., the centre of gravity was 9.7 inches aft of the datum point.
Limits 8.25" - 9.9" aft - extended by .01 chord to 10.8 inches aft.
On the ground the aileron control works freely and without play. Full movement of the control column can be obtained when the pilot is in the cockpit.
In the air the ailerons are light to handle when climbing and on the glide they become heavier with increase in speed, but by no more than is required to impart good "feel".
The ailerons are effective down to the stall and give adequate control when landing and taking off. The response is quick under all conditions of flight, and during all manoeuvres required from a fightling aeroplane.
There was no snatch or aileron vibration at any speed, and in general the aileron control is excellent for a high speed fighting aeroplane.
On the ground the rudder control operates freely and without play. There is an excellent adjustment for the position of the rudder bar. In the air it is moderately light and extremely effective. The rudder becomes heavier with increase of speed, but by no more than is necessary in a high speed aeroplane, and at the highest speeds it is still effective.
The aeroplane responds easily and quickly to the rudder under all conditions of flight.
Although the rudder is heavier than the ailerons, yet it should not be made lighter as with a very light rudder the pilot might overload the aeroplane at high speeds.
Rudder Bias Gear.
The rudder bias control is quick and easy to operate, it is effective and gives adequate range.
On the ground full movement of the elevators can be obtained. Operation is light and there is no play.
In the air the elevator control is light and very effective down to the stall.
Heaviness increases with speed, but by no more than is necessary. In the dive the aeroplane is steady. The elevators give rapid response with a small movement of the control column. When landing the control column need not be fully back.
The control is satisfactory as regards "feel" and response, but would be improved if the movement of the control column for a given movement of the elevators was slightly greater. A small movement of the control column produces so large an effect that an unskilled pilot might pull the nose of the aeroplane up too much when landing; however, a change to alter the gearing between control column and elevator is not considered advisable until spinning trials show it to be safe.
Tail Trimming Gear.
The tail trimming gear, which is of the trimmer tab type, is easy to operate and very effective. A very small movement of the lever has a powerful effect, and a lower gearing would be an advantage. There is adequate range for trim for all conditions of flight, in fact, only half the available movement of the lever is required.
Engine controls are well placed in the cockpit. They work easily and without play and do not slip.
The flaps are operated pneumatically and move down through an angle of 60°. Control is by a switch moved one way for "down" and the other way for "up". The system worked well and gave no trouble in maintenance.
When the flaps are down they reduce the stalling speed by about 12 m.p.h. A.S.I. (Uncorrected) and the aileron control is better at the stall with the flaps down than with them up. Putting the flaps down caused a noticeable change in trim, which can be easily taken up on the trimming gear or on the elevators.
Although these flaps appreciably reduce the flatness of glide, yet this aeroplane would be easier to bring in if the flaps were made more effective by putting the angle up to 90° or increasing their area.
Since this aeroplane was first flown at this Establishment the pilots have had the experience of very high drag flaps on several aeroplanes, and they are unanimous in their opinion that higher drag flaps on the Spitfire would improve its characteristics in the approach, and make it easier for an unskilled pilot to get into a small aerodrome.
If the flaps are modified to give higher drag, two "down" positions should be provided (say 60° and 90°) because a very high drag flap, although suitable for use in day time, involves too sudden a change of attitude when flattening out during at night.
The ideal system of operation is a small lever by which the flaps can be set to any position as required, but failing this, a system of operation to allow of two setting for the flaps at 60° and 90° is essential.
The brakes are hand operated with differential control on the rudder. They are smooth, progressive, easy to operate and effective. They do not tend to tip the aeroplane up at the end of the landing run.
Laterally the aeroplane is stable. If one wing is depressed and the control column released the aeroplane will return to a level keel in a reasonable time. Directionally the aeroplane is stable under all conditions of flight, engine on or off. Longitudinally the aeroplane is neutrally stable with engine on and stable in the glide. The aeroplane is unstable in the glide with flaps and undercarriage down.
In general the stability characteristics are satisfactory for a fighting aeroplane and give a reasonable compromise between controllability and steadiness as a gun platform.
Characteristics at the stall.
As the elevator control is very powerful the aeroplane will stall long before the control column is moved right back. The stall is normal. There is no vice nor snatch on the controls. In tight turns, giving approximately 3g. as registered on the accelerometer, at speeds from 140 m.p.h. A.S.I. downwards There was a distinct juddering on the whole aeroplane. Under these conditions the aeroplane is probably in a semi-stalled condition and this juddering effect may be due to slight buffeting on the tail. This can be stopped at once if the control column is eased forward.
Test according to A.D.M. 293 were done with the following results:-
On No. 1 test with the undercarriage and flaps up it is difficult to keep the aeroplane steady when the control column is right back. It wallows from side to side and there is a snatch on the control column from the elevators. With the unercarriage and flaps down the aeroplane is steadier in the stalled glide and there is no snatch.
In Test No. 2 with the undercarriage and flaps down it was possible to pull the wing up when ailerons were applied to unbank, but in turns both to the left and to the right, the aeroplane tends to take charge at the stall and cannot be said to comply with these tests when the control column is pulled right back.
In the third test with the undercarriage and flaps up, the wing can be pulled up, but in this test again the aeroplane takes charge to such an extent that the pilot found it almost impossible to make sure of centralising the rudder. With the unercarriage and flaps down the aeroplane's behaviour was much the same.
In tests Nos. 2 and 3 the movements of the aeroplane are more violent to the right than to the left after applying the controls. No spin resulted in either of these two tests.
This aeroplane, in common with other fighters tested at this Establishment, cannot be said to comply fully with tests Nos. 2 and 3, as its behaviour depends so much on the way the pilot uses his controls. Its behaviour in test No. 1 indicates that there is sufficient lateral control at the stall for a heavily loaded high speed aeroplane of this type.
Loops, half rolls off loops, slow rolls and stall turns have been done. The aeroplane is very easy and pleasant to handle in all acrobatics.
Landing and take-off.
The aeroplane is easy and normal to take-off. There is a slight tendency to swing, but this is not so pronounced as on a Fury and is automatically and easily corrected by the pilot. The aeroplane is simple and easy to land, but requires very little movement of the control as the elevator control is so powerful, and it is not necessary to have the control column fully back.
If the engine is opned up with the flaps and undercarriage down, the aeroplane can be easily held by the control column. The aeroplane does not swing when landing.
The aeroplane does not sideslip readily.
The ground handling is exceptionally good. The aeroplane is easy to turn and taxi in fairly strong winds. It is a more satisfactory aeroplane for operating in high winds than the normal biplane fighter.
The undercarriage has excellent shock absorbing qulaities, and good rebound damping.
The controls for the hydraulically retracting mechanism are simple and well arranged. The undercarriage can be raised in about 10 seconds and lowered in about 15 seconds, without undue effort. The indicators were satisfactory. The wheels cannot be seen, but when the undercarriage is lowered two small rods project through the wings to show its position.
When the undercarriage is fully up of down, the hand lever of the oil pump can no longer be moved, and this is a useful additional indication that the undercarriage is in the required position.
A Klaxon to warn the pilot that the undercarriage is up works when the throttle is pulled back beyond two thirds, but is not loud enough to be heard by him with the cockpit open and the engine on.
View forwards is fair and upwards is good. View to the rear is fair for a covered cockpit.
The present windscreen gives great distortion. If a curved windscreen of this shape cannot be made in either moulded glass or in a suitable material to give no distortion, it is considered that it should be replaced by a flat sided type, even though this might involve a slight reduction in performance.
With the cover open, the cockpit is remarkably free from draught, and it is possible to land and take-off with the cockpit cover open without using goggles.
The cockpit is comfortable and there is plenty of room, even for a big pilot. The head room is somewhat cramped for a tall pilot. It is not unduly noisy and the instruments and controls are well arranged. The cockpit is easy to enter and leave when the aeroplane is on the ground and foot steps on the wing are not considered necessary.
At speeds over 300 m.p.h. A.S.I. the cockpit cover is very difficult to open, although it has been opened at 320 m.p.h. A.S.I. and will stay open. Attention should be given to this question, as it is most important that the pilot should be able to get out of the aeroplane at the very highest speeds without difficulty. A small air flap operated by the handles on the sliding cover might make it easier to open at high speeds.
Although not heating is provided the cockpit was kept warm by heat from the engine and exhaust at 25,000 ft. Gloves were not necessary.
All instruments are well arranged and are clearly visible to the pilot. The compass is steady at all speeds.
The aeroplane is simple and easy to fly and has no vices. All controls are entirely satisfactory for this type and no modification to them is required, except that the elevator control might be improved by reducing the gear ratio between the control column and elevator. The controls are well harmonised and appear to give an excellent compromise between manoeuvrability and steadiness for shooting. Take-off and landing are straightforward and easy.
The aeroplane has rather a flat glide, even when the undercarriage and flaps are down and has a considerable float if the approach is made a little too fast. This defect could be remedied by fitting higher drag flaps.
In general the handling of this aeroplane is such that it can be flown by the average fully trained service fighter pilot, but there can be no doubt that it would be improved by having flaps giving a higher drag.