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.20266316Rotol240420
"6750"280465
L.154763632-pitch metal.280480
"6040Wooden fixed pitch370580

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.

AeroplaneWeight
lb.
AirscrewTime to Height (mins).
10,00015,00020,00025,00030,000
L.20266316Rotol Best
climbing speed
3.75.68.111.416.5
""Rotol Recommended
climbing speed
3.85.98.412.018.3
"6750Rotol       "4.66.99.814.022.1
L.15476040Wooden Fixed pitch4.36.59.313.522.0

Best climbing )-148 mph A.S.I. to 12,000ft. thereafter decreasing
speed 6,316 lbs) by 1½ m.p.h. per 1,000 ft.
 
Best climbing )-150 mph A.S.I. to 12,000ft. thereafter decreasing
Speed 6,750 lbs)by 1½ mph per 1,000ft.
 
Recommended)
Climbing Speed)-170 mph A.S.I to 12,000ft. thereafter decreasing
6,316lb and )by 1½ m.p.h. per 1000 ft.
6,750 lb. )

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

AEROPLANEHurricaneNo.    L.2026
 
SPEC. No.15/36
CONTRACT. 992405/39
CONTRACTOR.Messrs Hawker Aircraft Ltd..

TYPELandplaneDUTY    Single Seater Fighter.
 
ENGINES.Merlin IIINormal B.H.P    950/990 at Rated Altitude 12,250 ft
 
At     2,600     R.P.M.     at rated boost pressure +6 ¼ lb/sq.in. boost

 lb.
Tare weight4982
Weight light4566
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.

At Full Throttle
Height FeetSpeed M.P.HTime to Climb MinsRate of Climb ft/min
   S.L    0     0
   2000 0.752610
   5000276    1.9  2625
   10000291    3.8  2640
   15000307    5.852250
   20000316    8.351675
   25000307    12.0   1100
   30000292    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 secsDistance from rest to clear 50 ft. screen 420 yds.
                    Flaps & u/c down 63
Stalling speed (A.S.I.) 57 M.P.HGliding 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

TYPELandplaneDUTY    Single Seater Fighter.
 
ENGINES.Merlin IIINormal B.H.P    950/990 at Rated Altitude 12,250 ft
 
At     2,600     R.P.M.     at rated boost pressure +6 ¼ lb/sq.in. boost

 lb.
Tare weight4982
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.

At Full Throttle
Height FeetSpeed M.P.HTime to Climb MinsRate of Climb ft/min
   S.L    0  0
   2000 1.02080
   5000      2.35 2175
   10000    4.62330
   15000302     6.852010
   20000309     9.351465
   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. - secsDistance from rest to clear 50 ft. screen 465 yds.
                   
Stalling speed - M.P.HGliding 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


AircraftHurricane L.2026
EngineMerlin III

AIRSCREW. (from Log Book)

PositionCentre.   
Constant airscrew.Rotol   
Type.-   
Serial No.R.R.M.S.7.   
Makers No.- 
Diameter.10'9"   
No. of Blades3
Direction of rotation.R.H.   
A.M. Serial Nos.- Hub.R.R.M.S.7.   
    "       "         "   Blade No.1C.18505   
    "       "         "       "     No.2C.18506   
    "       "         "       "     No.3C.18507   
Basic pitch setting.-
Pitch range.35°
High pitch setting.56°   -   40'
Low pitch setting.21°   -   40'


CLIMBING TRIALS
Weight:- 6316 lb.

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 Level0         Controlling
at
2600
R.P.M.
  
  1,0000.42610167   169.5-4.8-0.1+6.25
  2,000  0.752615169.5169.5-4.8-0.1+6.25
  3,000  1.152620172   169.5-4.8-0.1+6.25
  5,0001.92625177.5169.5-4.8-0.2+6.25
  6,5002.52630181.5169.5-4.8-0.3+6.25
10,0003.82640191.5169.5-4.8-0.5+6.25
13,0005.02485197.5167   -4.6-0.7+5.25
15,000  5.852250200.5164   -4.3-0.7+3.9  
16,5006.52080202.5161.5-4.1-0.8+2.95
18,0007.31910205   159.5-3.8-0.9+2.0  
20,000  8.351675209   157   -3.8-1.0+0.8  
23,00010.3   1330214   152.5-3.2-1.1-0.95
26,00012.95  990219   148   -2.7-1.2-2.55
28,00015.25  755223   145   -2.4-1.3-3.6  
30,00018.3     530227   142   -2.0-1.4-4.6  
  11,600* 4.42645195   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 6¼Boost 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
Weight:- 6750 lb.

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.
  
  1,0000.52080167   169.5-4.8-0.1+6.25
  2,0001.02080169.5169.5-4.8-0.1+6.25
  3,000  1.452110172   169.5-4.8-0.1+6.25
  5,000  2.352175177.5169.5-4.8-0.2+6.25
  6,500  3.052220181.5169.5-4.8-0.3+6.25
10,0004.62330191.5169.5-4.8-0.5+6.25
13,0005.92230195.5165   -4.4-0.6+5.3  
15,000  6.852010197   161   -4.0-0.7+3.95
16,5007.51845199.5159   -3.8-0.8+3.05
18,0008.51680202   156.5-3.5-0.9+2.1  
20,000  9.751465204   153   -3.2-0.9+1.0  
23,00012.051140219   148.5-2.7-1.0-0.65
26,00015.1    810213   143.5-2.2-1.1-2.2  
28,00017.95  580217   140.5-1.8-1.2-3.2  
30,00022.1    375220   137.0-1.5-1.3-4.15
  11,600* 5.32380193   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 6¼Boost 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
Weight:- 6316 lb.

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         
  5,000276   267   -10.0-0.8 
  6,500280.5265.5-10.0-1.0 
10,000291.5262   -10.0-1.7+6.25
13,000301   258.5-10.0-2.2+6.25
15,000307   256   -10.0 -2.6+6.25
16,500312   254.5-10.0-2.9+6.25
18,000316   252   -9.9  -3.2+6.05
20,000314.5243   -9.8  -3.4+4.85
23,000310.5228   -9.2  -3.4+2.5  
26,000305   212.5-8.3  -3.4+0.75
28,000299.5200.5-7.4  -3.3-0.35
30,000292.5188.5-6.6  -3.2-1.4  
  17,750*316   252.5-9.9  -3.1+6.25
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.
 
* Full Throttle Height
Note 1:- For position error correction curve and position of pressure head see Fig.13 and 13A.
 


SPEED TRIALS
Weight:- 6750 lb.

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           
15,000302   251.5-9.9  -2.5+6.25
16,500308   251   -9.9  -2.8+6.25
18,000310.5247   -9.8  -3.0+5.5  
20,000309.5239   -9.7  -3.2+3.75
23,000302   221   -8.8  -3.2+1.4  
26,000           
28,000         
30,000         
  17,200*310.5250   -9.9  -2.9+6.25
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
 
    Take-off and Landing Runs 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 yards.
 
    Landing run 325 yards.
 
* Full Throttle Height
Note 1:- For position error correction curve and position of pressure head see Fig.13 and 13A.
 
RATE OF CLIMB & TIME TO HEIGHT
LEVEL SPEEDS & BOOST AT HEIGHTS

WWII Aircraft Performance