ag351

1. Introduction:

...........Brief performance trials, including take-off tests and position error tests, have been completed on this aeroplane. Owing to abnormally high oil temperatures due to coring of the cooler in the winter months, tests had to be made with various types of blanks over the oil cooler and radiator; details of these blanks will be given in the report on cooling trials which will follow later. The tests were made during the period January to April, 1942.

2. Condition of aircraft relevant to tests.

...........The aircraft was fitted with an aerial mast behind the cockpit hood with aerials stretching from the fin tip to the mast and from both tail plane tips to the sides of the fuselage aft of the wing fairing. The armament consisted of 2 x 0.5" guns projecting out of the cowling beneath the engine and 4 x .300" and 2 x 0.5" guns mounted in the wings. The wing gun ports remained sealed throughout the tests. A small bead sight was fitted in front of the pilots windscreen.

...........Individual stub ejector exhausts were fitted on this aircraft. No snowguards or air cleaners were fitted to the air intake.

...........The radiator is an annular honeycomb type situated in the bottom of the fuelage aft of the trailing edge wing fairing. The oil cooler is also of the honeycomb type and forms the core to the radiator annulus. The large intake scoop and exit duct flaps fitted to the radiator cowling ar adjustable in flight, as is the spoiler flap, which is fitted in front of radiator inlet duct for use in dives.

...........This aeroplane was fitted with a fully retractable tail wheel.

...........The total fuel capacity of the aircraft is 140 gallons of petrol and 10 gallons of oil.

...........The all-up weight during the tests was 8,625 lb. with the centre of gravity 0.8 inches aft of the datum. The A& A.E.E. C.G. limits are 2.3 inches forward and 2.7 inches aft of the datum, (including 1% S.M.C. extension).

...........The centre of gravity was measured with the undercarriage down.

3. Tests made:

...........Several climbs were made with and without blanks fitted on the radiator unit. The performance on the climb was the same in both cases. The best initial climbing speed of 170 m.p.h. A.S.I. was taken from American reports but three climbs were also done at 160 m.p.h. A.S.I. and the time to height was aprroximately the same in both cases.

...........Level speed measurements were made both with and without the radiator blanks fitted.

...........Take-off tests at three different flap settings and also landing tests were made. Preliminary crosswind take-offs and landings were also made in winds up to 25 m.p.h.

...........The position error was measured by the aneroid method throughout the speed range with flaps and undercarriage up.

4. Results of tests:

....4.1 Climb: The best rate of climb was 1,980 feet/minute at 11,300 feet. The estimated absolute ceiling is 31,000 feet and the Service ceiling is 30,000 feet with the radiator intake scoop and exit duct in the minimum drag position. The best climbing speed is 170 m.p.h. A.S.I. up to 11,000 feet and then reducing speed by 2 m.p.h. A.S.I. per thousand feet.

....4.2 Level speeds: The maximum all-out level speed was 370 m.p.h. true air speed at 15,000 feet with the radiator blanks removed. With the various blanks fitted this speed was lowered by 13 m.p.h. and the full throttle height fell to 14,700 feet due to the decreased effect of ram brought about by the decrease in speed.

....4.3 Take-off tests: Take-off tests were done at three different indicated flap settings, zero flap, 15 deg. flap and 30 deg. flap. At 30 deg. flap full aileron was necessary to keep the left wing up; it was therefore considered undesirable to take off with 45 deg. flap. The results show that the optimum conditions are obtained with 15 deg. flap. The measured distances are tabulated below.

Corrected to standard conditions and zero wind.
Flap setting 15 deg. indicated (20 deg. true)
Take-off run335 yards
Distance from rest to clear 50 ft. screen640 yards
Time for take-off16.5 seconds
A.S.I. on take-off80 m.p.h.
A.S.I. of climb away100 m.p.h.

Under conditions of test
Mean wind1.6 m.p.h.
Ground pressure29.32" Hg.
Ground temperature+15 deg. C.
Take-off run346 yards
Distance from rest to clear 50 ft. screen645 yards
R.P.M. at take-off2950
Boost at take-off44.7" of Hg.

....4.4 Take-off technique: Take-off is satisfactory and straightforward although the tail has to be lifted early and the control column eased back to bring the tail down just before take-off. There is no appreciable tendency to swing and the take-off was smooth and steady. There is little change of trim when the under-carriage is raised. The flaps can be safely raised at a speed of 120 m.p.h. A.S.I. at a height of 500 feet. The aircraft then becomes slightly tail heavy but the actual change of trim is very small.

...........The best elevator trimmer setting for take-off varies between 0 and +5 divisons on the trimmer control indicator, depending on the flap setting, that is, for zero flap setting 0 to +3 is recommended and for 15 deg. flap +5 is recommended.

...........Crosswind take-offs present no difficulty with this aircraft in winds up to 25 m.p.h. The tendency th swing down wind is easily corrected by use of rudder. The locking of the tail wheel is recommended before take-off.

....4.5 Landing tests: Landing tests were made with engine-assisted approach at the full flap setting of 45 deg. indicated. The landing run appears rather excessive, but this was due to the pilot not being able to use full brake owing to the bumpy state of the aerodrome. It is considered that the landing run could be shortened considerably if the tests had been made on a runway or smoother aerodrome. The measured values obtained are tabulated below:-

Corrected to standard conditions and zero wind.
Flap setting 42 deg. indicated (true 52 deg.)
Landing run700 yards
Time from touch-down to come to rest24 seconds
A.S.I. on touch-down80 m.p.h.
Engine-assisted approach A.S.I. flap and undercarriage down95 m.p.h.

Under conditions of test
Mean wind5.5 m.p.h.
Ground pressure29.32" Hg.
Ground temperature+13 deg. C.
Landing run660 yards

....4.6 Landing technique: Landing with full flap is straightforward and comparitively easy. Engine assisted approach is recommended as it gives more control and a lower speed to touch down. The aircraft becomes slightly nose heavy when the flaps and undercarriage are lowered, but the change in trim is small. There is adequate elevator control at touch down. The brakes could not be used to the full as the aerodrome was too bumpy.

...........The climb away from a baulked landing is good and the flaps and undercarriage can be raised at 120 m.p.h. A.S.I. without any appreciable sinking away. The change in trim is small when the engine is opened up, the aircraft becoming slightly tail heavy.

...........Approach and landing in cross winds of up to 25 m.p.h. were not difficult but there is barely sufficient aileron control to effect the required amount of sideslip, such as would be necessary to land cross wind on a runway. With the tail wheel fixed, which our pilots recommend, rudder alone was necessary to check the tendency to swing into wind after touch-down.

TABLE I
Performance on the climb

Standard
Height
feet
Time
from
start
mins
Rate of
climb
ft/min.
T.A.S.
m.p.h.
A.S.I.
m.p.h.
P.E.C.E.R.P.M.Boost
ins. of
Hg.
Radiator
shutter
Sea level0--------
  2,0001.11855175170-.2-.1257036.91/3 open
  4,0002.151880180170-.2-.1"""
  6,0003.21910185.5170-.2-.2"""
10,0005.31960197170-.2-.5"""
  11,300*5.951980201170-.2-.6"""
12,0006.31910201.51680-.6"35.8"
14,0007.41710203164+.4-.7"33.2"
16,0008.651510205.5160+.8-.7"30.9"
18,00010.11305207156+1.2-.7"28.7"
20,00011.751105209152+1.6-.8"26.6Shut
22,00013.75910211148+2.0-.9"24.7"
24,00016.25705212143+2.4-.9"22.9"
26,00019.55505214139+2.8-.9"21.1"
28,00024.6305211131+3.5-.8"19.5"
29,75033.1130212127+3.9-.8"18.0"

................* Full throttle height: 11,300 feet.
...................Estimated absolute ceiling = 31,000 feet
...................Service ceiling (100 feet/minute) = 30,000 feet

Propeller details

Type:Curtis Electric (constant speed) C.5315 S.D.8.No. of blades:3
Diameter:10' 6"Rotation:R.H.Serial No.:8102
Hub Serial No.:L3160PPitch range:30 deg.Blade material:Hollow steel
Blade No. 1:19668Coarse pitch setting:58 deg.
Blade No. 2:19821Fine pitch setting:23 deg.
Blade No. 3:20002Fully feathered setting:57.6 deg.

TABLE II
LEVEL SPEEDS AND BOOST
AT HEIGHT
Radiator shutter closed. Radiator and oil cooler blanks removed.

Standard
Height
feet
True air
speed
m.p.h.
A.S.I.
m.p.h.
Position
error
correction
m.p.h.
Compressibility
correction
m.p.h.
R.P.M.Boost
Ins. of Hg.
  9,000350321-13.3-2.1296041.7
10,000353318.5-13.1-2.3"41.7
12,000360314.5-12.7-2.7"41.7
14,000366.5311-12.4-3.2"41.7
  15,000*370308.5-12.2-3.5"41.7
16,000369303.5-11.8-3.6"40.0
18,000365.5290.5-10.6-3.9"37.0
20,000360.5276.5-9.5-4.0"34.2
21,000357.5269.5-8.9-4.0"32.9

................* Full throttle height = 15,000 feet.

Radiator shutter closed. Radiator and oil cooler blanks fitted.

  9,000336307.5-12.2-1.9294041.7
10,000340306-12.0-2.0"41.7
12,000347302.5-11.6-2.5"41.7
14,000354.5300.5-11.5-3.0"41.7
  14,700*357298.5-11.3-3.1"41.7
16,000355291-10.7-3.3"39.5
18,000351.5278.5-9.7-3.5"36.5
20,000348266-8.6-3.6"33.7
22,000344254-7.5-3.7"31.2

................* Full throttle height = 14,700 feet.

Fig 1 TIME TO HEIGHT RATE OF CLIMB AND BOOST
Fig 2 LEVEL SPEEDS & BOOST AT HEIGHT

[Weights and Loading data] [Handling trials]