Introduction.
In accordance with a request from the Resident Technical Officer at Messers. Hawkers Limited, Kingston-on-Thames, dated 5th October 1939, brief trials have been carried out on this aeroplane to compare its performance with that of other Hurricanes fitted with two-pitch airscrews. These trials were extended to include the effect of increasing the all up weight by 434 lb. to 6750 lb. in accordance with Air Ministry letter, reference B.999903/39/R.D.L.1 dated 15th February 1940.
1.0 Comments of Trials.
The aeroplane was delivered with the early production pattern of windscreen which is practically flush fitting on the outside, and armour plating over the fuel tank in the fuselage. The latter modification was not incorporated in L.1547 when that Hurricane was tested in turn with the wooden fixed pitch and metal two-pitch airscrews. (See Part of Report No.M/689/a dated 9th October 1939 and 21st January 1939 respectively). It is unlikely that the performance of L.2026 has been affecrted by the armour plating.
All the tests at 6316 lb. had been completed with the exception of a full throttle climb when the engine was damaged and had to be replaced. This climb and the trials at 6750 lb. were therefore carried out with a new engine.
2.0 Take-off (pages 10,10(a). Fig.17)..
The take-off run in zero wind and under standard atmospheric conditions is better than that of the 2-pitch airscrew Hurricane. The accompanying table gives the take-off for 3 types of airscrew and for the overload Rotol case. The use of 20 ° flap for 6,750 lb. on the Rotol Hurricane shortened the run and distance to screen by 15 yards.
| Aeroplane. | Weight lb. | Airscrew. | Take-off run 'yds' zero flap. | Distance to clear 50 ft. screen (yds) |
|---|---|---|---|---|
| L.2026 | 6316 | Rotol | 240 | 420 |
| " | 6750 | " | 280 | 465 |
| L.1547 | 6363 | 2-pitch metal. | 280 | 480 |
| " | 6040 | Wooden fixed pitch | 370 | 580 |
3.0 Climb (Pages 9,9a).
It was found that at normal load the best climbing speed as determined from partial climbs was not suitable owing to the instability and uncomfortably steep attitude obtaining at this speed when at high altitudes. The climbing speed was increased by 20 mph to 170 mph A.S.I., a more suitable speed which improved the handling qualities of the aeroplane on the climb. The same procedure had to be adopted in the overload case.
The following table gives comparative times in minutes to reach various heights for the best climbing speed and recommended climbing speed at normal load. Also included are the times to height for the overload case and for a Hurricane with a fixed pitch airscrew. No figures are available for a climb with a two-pitch airscrew.
| Aeroplane | Weight lb. | Airscrew | Time to Height (mins). | ||||
|---|---|---|---|---|---|---|---|
| 10,000 | 15,000 | 20,000 | 25,000 | 30,000 | |||
| L.2026 | 6316 | Rotol Best climbing speed | 3.7 | 5.6 | 8.1 | 11.4 | 16.5 |
| " | " | Rotol Recommended climbing speed | 3.8 | 5.9 | 8.4 | 12.0 | 18.3 |
| " | 6750 | Rotol " | 4.6 | 6.9 | 9.8 | 14.0 | 22.1 |
| L.1547 | 6040 | Wooden Fixed pitch | 4.3 | 6.5 | 9.3 | 13.5 | 22.0 |
| Best climbing speed 6,316 lbs | 148 mph A.S.I. to 12,000ft. thereafter decreasing by 1½ m.p.h. per 1,000 ft. | |
| Best climbing speed 6,750 lbs | 150 mph A.S.I. to 12,000ft. thereafter decreasing by 1½ m.p.h. per 1,000 ft. | |
| Recommended climbing speed 6,316lb and 6.750 lb. | 170 mph A.S.I. to 12,000ft. thereafter decreasing by 1½ m.p.h. per 1,000 ft. |
4.0 Level Speeds (Page 10).
In addition to the routine speed tests on this aeroplane as delivered, subsidiary tests were made to determine the effect of engine r.p.m. on the top speed. Further tests were made at overload.
4.1 Controlling R.P.M.
Speed tests were made at 13,000 and 9,000 ft with the boost pressure maintained constant at 6¼ lb. per sq.in whilst the R.P.M. was varied over a range from 2,600 to 3,000. These tests were made to determine whether the maximum speed was attained with the airscrew controlling at 2,800 r.p.m. as found to be on Rotol Spitfire N.3171 (See first part of report A.&.A.E.E.692,d March 1940). The maximum speed of the Hurricane was attained with the airscrew controlling at 3,000 r.p.m.
4.2 Overload.
Increasing the weight from 6,316 lb. to 6,750 lb. had the effect of reducing the maximum level speed by 6 m.p.h. from 316 to 310 m.p.h. though it should be noted that the engine was changed between the two sets of results.
5.0 Interconnection between throttle and airscrew control. (Drg.No.1811)
A device has been incorporated to prevent the engine being opened up with the airscrew controlling at low engine speeds. It consists of a length of Bowden cable attached at one end to the lower arm of the throttle lever and at the other end to the constant speed control lever. When the engine control is moved forward the C.S. control, if inadvertently left in the low r.p.m. position, is pulled forward into a high r.p.m. setting. These are the only circumstances under which the interconnection system functions, normal independent operation of the two controls being possible otherwise.
This device has proved satisfactory in all conditions of flight and should eliminate risk of damage to an engine due to the above cause.
SUMMARY OF TRIALS
at Normal Load
at Normal Load
| AEROPLANE | Hurricane | No. | L.2026 |
| SPEC. No. | 15/36 | ||
| CONTRACT. | 992405/39 | ||
| CONTRACTOR. | Messrs Hawker Aircraft Ltd. | ||
| TYPE | Landplane | DUTY | Single Seater Fighter. |
| ENGINES. | Merlin III | Normal B.H.P | 950/990 at Rated Altitude 12,250 ft |
| At 2,600 R.P.M. and at rated boost pressure +6 ¼ lb/sq.in. boost | |||
| lb. | |||
| Tare weight | 4982 | ||
| Weight light | 4566 | ||
| Fixed military load | 316 | ||
| Service Load | 677 | ||
| Fuel 78.5 gallons* | 589 | ||
| Oil 7.5 | 68 | ||
| Flying weight on trials. | 6316 | ||
| * Based on 7.5 lb. per gallon. | |||
| Height Feet | Speed M.P.H | Time to Climb Mins | Rate of Climb ft/min |
|---|---|---|---|
| S.L | 0 | 0 | |
| 2000 | 0.75 | 2610 | |
| 5000 | 276 | 1.9 | 2625 |
| 10000 | 291 | 3.8 | 2640 |
| 15000 | 307 | 5.85 | 2250 |
| 20000 | 316 | 8.35 | 1675 |
| 25000 | 307 | 12.0 | 1100 |
| 30000 | 292 | 18.3 | 530 |
| Height Feet | Speed M.P.H | Time to Climb Mins | Rate of Climb ft/min |
|---|---|---|---|
| S.L | 0 | 0 | |
| 2000 | 0.75 | 2610 | |
| 5000 | 276 | 1.9 | 2625 |
| 10000 | 291 | 3.8 | 2640 |
| 15000 | 307 | 5.85 | 2250 |
| 20000 | 316 | 8.35 | 1675 |
| 25000 | 307 | 12.0 | 1100 |
| 30000 | 292 | 18.3 | 530 |
| Service ceiling | 33,750 (estimated) ft. | Landing speed | -- M.P.H |
| Take off run | Flaps & u/c up: 77 | Time. | 11.5 secs |
| Flaps & u/c down: 63 | |||
| Distance from rest to clear 50ft. screen: | 420yds. | ||
| Stalling speed (A.S.I.) | 57 M.P.H | Gliding in A.S.I. | 88 M.P.H. |
| Best landing A.S.I. | -- M.P.H | ||
| Distance to rest (with brakes) After clearing 50 ft. screen | -- | ||
| Landing and take off tests corrected to zero wind and standard atmosphere | |||
SUMMARY OF TRIALS
On overload
On overload
| TYPE | Landplane | DUTY | Single Seater Fighter. |
| ENGINES. | Merlin III | Normal B.H.P | 950/990 at Rated Altitude 12,250 ft |
| At 2,600 R.P.M. and at rated boost pressure +6 ¼ lb/sq.in. boost | |||
| lb. | |||
| Tare weight | 4982 | ||
| Weight light | -- | ||
| Fixed military load | -- | ||
| Service Load | 1111 | ||
| Fuel 78.5 gallons* | 589 | ||
| Oil 7.5 | 68 | ||
| Flying weight on trials. | 6750 | ||
| * Based on 7.5 lb. per gallon. | |||
| Height Feet | Speed M.P.H | Time to Climb Mins | Rate of Climb ft/min |
|---|---|---|---|
| S.L | 0 | 0 | |
| 2000 | 1.0 | 2080 | |
| 5000 | 2.35 | 2175 | |
| 10000 | 4.6 | 2330 | |
| 15000 | 302 | 6.85 | 2010 |
| 20000 | 309 | 9.35 | 1465 |
| 25000 | 13.95 | 920 | |
| 30000 | 22.1 | 375 |
| Service ceiling | 32.500(estimated) ft. | Landing speed | -- M.P.H |
| Take off run | 280 yds. | Time. | --- |
| Distance from rest to clear 50ft. screen: | 465yds. | ||
| Stalling speed (A.S.I.) | -- | Gliding in A.S.I. | 98 M.P.H. |
| Best landing A.S.I. | 69 M.P.H | ||
| Distance to rest (with brakes) After clearing 50 ft. screen | -- | ||
| Landing and take off tests corrected to zero wind and standard atmosphere | |||
| Aircraft | Hurricane L.2026 |
| Engine | Merlin III |
| AIRSCREW. (from Log Book) | |
|---|---|
| Position | Centre. |
| Constant airscrew. | Rotol |
| Type. | -- |
| Serial No. | R.R.M.S.7. |
| Makers No. | -- |
| No. of Blades | 3 |
| Diameter. | 10'9" |
| Direction of rotation. | R.H. |
| A.M. serial Nos.- Hub. | R.R.M.S.7. |
| A.M. serial Nos.- Blades No.1 | C.18505 |
| A.M. serial Nos.- Blades No.2 | C.18506 |
| A.M. serial Nos.- Blades No.3 | C.18507 |
| Basic pitch setting. | -- |
| Pitch range. | 35° |
| High pitch setting. | 56° - 40' |
| Low pitch setting. | 21° - 40' |
CLIMBING TRIALS
| Height in Standard Atmosphere Feet |
Time From Start Min. |
Rate of Climb Ft./Min. |
True Air Speed M.P.H. |
A.S.I. M.P.H. |
Position Error Correction & Compressibility P.E.C. | Comp. |
R.P.M. | Boost lb./sq. in. |
Radiator | |
|---|---|---|---|---|---|---|---|---|---|
| Sea Level | 0 | Controlling at 2600 R.P.M. | |||||||
| 1,000 | 0.4 | 2610 | 167 | 169.5 | -4.8 | -0.1 | +6.25 | ||
| 2,000 | 0.75 | 2615 | 169.5 | 169.5 | -4.8 | -0.1 | +6.25 | ||
| 3,000 | 1.15 | 2620 | 172 | 169.5 | -4.8 | -0.1 | +6.25 | ||
| 5,000 | 1.9 | 2625 | 177.5 | 169.5 | -4.8 | -0.2 | +6.25 | ||
| 6,500 | 2.5 | 2630 | 181.5 | 169.5 | -4.8 | -0.3 | +6.25 | ||
| 10,000 | 3.8 | 2640 | 191.5 | 169.5 | -4.8 | -0.5 | +6.25 | ||
| 13,000 | 5.0 | 2485 | 197.5 | 167 | -4.6 | -0.7 | +5.25 | ||
| 15,000 | 5.85 | 2250 | 200.5 | 164 | -4.3 | -0.7 | +3.9 | ||
| 16,500 | 6.5 | 2080 | 202.5 | 161.5 | -4.1 | -0.8 | +2.95 | ||
| 18,000 | 7.3 | 1910 | 205 | 159.5 | -3.8 | -0.9 | +2.0 | ||
| 20,000 | 8.35 | 1675 | 209 | 157 | -3.8 | -1.0 | +0.8 | ||
| 23,000 | 10.3 | 1330 | 214 | 152.5 | -3.2 | -1.1 | -0.95 | ||
| 26,000 | 12.95 | 990 | 219 | 148 | -2.7 | -1.2 | -2.55 | ||
| 28,000 | 15.25 | 755 | 223 | 145 | -2.4 | -1.3 | -3.6 | ||
| 30,000 | 18.3 | 530 | 227 | 142 | -2.0 | -1.4 | -4.6 | ||
| 11,600* | 4.4 | 2645 | 195 | 169.5 | -4.8 | -0.6 | +6.25 | ||
| Estimated absolute ceiling | 33,750' | Greatest height reached. | 32,800 | ||||||
| R.P.M. stationary on ground. | 2900 at 6¼ Boost pressure lb./sq.in | ||||||||
| * Full throttle height. | |||||||||
| ** Service ceiling. 33,750' (Estimated) | |||||||||
| Note1:- For position error correction curve and position of pressure head see Fig. 13 & 13A. | |||||||||
CLIMBING TRIALS
| Height in Standard Atmosphere Feet |
Time From Start Min. |
Rate of Climb Ft./Min. |
True Air Speed M.P.H. |
A.S.I. M.P.H. |
Position Error Correction & Compressibility P.E.C. | Comp. |
R.P.M. | Boost lb./sq. in. |
Radiator | |
|---|---|---|---|---|---|---|---|---|---|
| Sea Level | 0 | Controlling at 2600 R.P.M. | |||||||
| 1,000 | 0.5 | 2080 | 167 | 169.5 | -4.8 | -0.1 | +6.25 | ||
| 2,000 | 1.0 | 2080 | 169.5 | 169.5 | -4.8 | -0.1 | +6.25 | ||
| 3,000 | 1.45 | 2110 | 172 | 169.5 | -4.8 | -0.1 | +6.25 | ||
| 5,000 | 2.35 | 2175 | 177.5 | 169.5 | -4.8 | -0.2 | +6.25 | ||
| 6,500 | 3.05 | 2220 | 181.5 | 169.5 | -4.8 | -0.3 | +6.25 | ||
| 10,000 | 4.6 | 2330 | 191.5 | 169.5 | -4.8 | -0.5 | +6.25 | ||
| 13,000 | 5.9 | 2230 | 195.5 | 165 | -4.4 | -0.6 | +5.3 | ||
| 15,000 | 6.85 | 2010 | 197 | 161 | -4.0 | -0.7 | +3.95 | ||
| 16,500 | 7.5 | 1845 | 199.5 | 159 | -3.8 | -0.8 | +3.05 | ||
| 18,000 | 8.5 | 1680 | 202 | 156.5 | -3.5 | -0.9 | +2.1 | ||
| 20,000 | 9.75 | 1465 | 204 | 153 | -3.2 | -0.9 | +1.0 | ||
| 23,000 | 12.05 | 1140 | 219 | 148.5 | -2.7 | -1.0 | -0.65 | ||
| 26,000 | 15.1 | 810 | 213 | 143.5 | -2.2 | -1.1 | -2.2 | ||
| 28,000 | 17.95 | 580 | 217 | 140.5 | -1.8 | -1.2 | -3.2 | ||
| 30,000 | 22.1 | 375 | 220 | 137.0 | -1.5 | -1.3 | -4.15 | ||
| 11,600* | 5.3 | 2380 | 193 | 167 | -4.6 | -0.6 | +6.25 | ||
| Estimated absolute ceiling | 32,500' | Greatest height reached. | 31,000 | ||||||
| R.P.M. stationary on ground. | 2900 at 6¼ Boost pressure lb./sq.in | ||||||||
| * Full throttle height. | |||||||||
| ** Service ceiling. 32,250' (Estimated) | |||||||||
| Note1:- For position error correction curve and position of pressure head see Fig. 13 & 13A. | |||||||||
SPEED TRIALS
| Height in Standard Atmosphere Feet |
True Air Speed M.P.H. |
A.S.I. M.P.H. |
Position Error Correction & Compressibility P.E.C. | Comp. |
R.P.M. | Boost lb./sq. in. |
Speed at Normal Revs. |
|
|---|---|---|---|---|---|---|---|
| Sea Level | Controlling at 3000 R.P.M. | ||||||
| 1,000 | |||||||
| 2,000 | |||||||
| 3,000 | |||||||
| 5,000 | 276 | 267 | -10.0 | -0.8 | |||
| 6,500 | 280.5 | 265.5 | -10.0 | -1.0 | |||
| 10,000 | 291.5 | 262 | -10.0 | -1.7 | +6.25 | ||
| 13,000 | 301 | 258.5 | -10.0 | -2.2 | +6.25 | ||
| 15,000 | 307 | 256 | -10.0 | -2.6 | +6.25 | ||
| 16,500 | 312 | 254.5 | -10.0 | -2.9 | +6.25 | ||
| 18,000 | 316 | 252 | -9.9 | -3.2 | +6.05 | ||
| 20,000 | 314.5 | 243 | -9.8 | -3.4 | +4.85 | ||
| 23,000 | 310.5 | 228 | -9.2 | -3.4 | +2.5 | ||
| 26,000 | 305 | 212.5 | -8.3 | -3.4 | +0.75 | ||
| 28,000 | 299.5 | 200.5 | -7.4 | -3.3 | -0.35 | ||
| 30,000 | 292.5 | 188.5 | -6.6 | -3.2 | -1.4 | ||
| 17,750* | 316 | 252.5 | -9.9 | -3.1 | +6.25 | ||
| * Full Throttle Height | |||||||
| Landing and take off tests corrected to zero wind and standard atmosphere. | |||||||
| Take off run | 240 yds | Time | - secs. | ||||
| Distance from rest to clear 50 foot screen | 420 yds. | ||||||
| Gliding in A.S.I. | 88 M.P.H. | Stalling speed | -- | ||||
| Best landing A.S.I. | 67 M.P.H. | ||||||
| Distance to rest (with brakes) after passing over 50 ft. screen | -- yds. | ||||||
| Landing run with brakes | 280 yds. | Landing run without brakes | - yds | ||||
| Under Conditions of Test: | i.e. Wind 13.0 m.p.h. pressure 29.20 "Hg. Temp. +9°C. | ||||||
| Take off run | 190 yards. | Distance from rest to clear 50 ft screen | 330 yards. | ||||
| Landing run | 205 yards. | ||||||
| Note 1:- For position error correction curve and position of pressure head see Fig.13 and 13A | |||||||
SPEED TRIALS
| Height in Standard Atmosphere Feet |
True Air Speed M.P.H. |
A.S.I. M.P.H. |
Position Error Correction & Compressibility P.E.C. | Comp. |
R.P.M. | Boost lb./sq. in. |
Speed at Normal Revs. |
|
|---|---|---|---|---|---|---|---|
| Sea Level | Controlling at 3000 R.P.M. | ||||||
| 1,000 | |||||||
| 2,000 | |||||||
| 3,000 | |||||||
| 5,000 | |||||||
| 6,500 | |||||||
| 10,000 | |||||||
| 13,000 | |||||||
| 15,000 | 302 | 251.5 | -9.9 | -2.5 | +6.25 | ||
| 16,500 | 308 | 251 | -9.9 | -2.8 | +6.25 | ||
| 18,000 | 310.5 | 247 | -9.8 | -3.0 | +5.5 | ||
| 20,000 | 309.5 | 239 | -9.7 | -3.2 | +3.75 | ||
| 23,000 | 302 | 221 | -8.8 | -3.2 | +1.4 | ||
| 26,000 | |||||||
| 28,000 | |||||||
| 30,000 | |||||||
| 17,200* | 310.5 | 250 | -9.9 | -2.9 | +6.25 | ||
| * Full Throttle Height | |||||||
| Landing and take off tests corrected to zero wind and standard atmosphere. | |||||||
| Take off run | 280 yds | Time | - secs. | ||||
| Distance from rest to clear 50 foot screen | 420 yds. | ||||||
| Gliding in A.S.I. | 98 M.P.H. | Stalling speed | -- | ||||
| Best landing A.S.I. | 69 M.P.H. | ||||||
| Distance to rest (with brakes) after passing over 50 ft. screen | -- yds | ||||||
| Landing run with brakes | 330 yds. | Landing run without brakes | -- yds | ||||
| Under conditions of test i.e.: | Wind 0.5 m.p.h. pressure 29.59 "Hg. Temp. +3°C. | ||||||
| Take off run | 265 yards | Distance from rest to clear 50 ft screen | 450 yds | ||||
| Landing run | 325 yds | ||||||
| Note 1:- For position error correction curve and position of pressure head see Fig.13 and 13A. | |||||||
