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SUPERMARINE SPITFIRE Mk.VIII PERFORMANCE


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#1 CORSNING

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Posted 23 October 2013 - 05:05 PM

Spitfire Mk.VIII Merlin 66 / +18 lbs. & +25 lbs.Boost.

Report: Vickers-Armstrong, Worthy Down, Spitfire Mk.VIII JF 275. Engines (all) Merlin 66. No date given. I could not find a full report on JF. 275. The following performance is estimated from several points given on a chart and comparing them to the graphs of the full test of A/C No. JF.934. The Mk.VIII's performance was similar to the Mk.IX's under the same conditions. The first set of figures are at an engine boost of +18 psi. The second set are at a boosting of (+25 psi)

 

Performance (Most Estimated):

 

Altitude.Speed/Climb 

Meters..mph/fpm

S.L.......338/4610-(362/5580)

.1,000..351/4610-(371/5085)

.2,000..364/4585-(380/5080)

.3,000..374/4125-(391/5095)

.4,000..376/3980-(405/4745)

.5,000..386/4005-(408/3835)

.6,000..403/3620-(405/3620)

Feet--------------------------------

.5,000..358/4610-(376/4825)

10,000.373/4100-(391/5095)

15,000.384/3995-(408/4425)

20,000.404/3565-(405/3565)

 

Speed +18 psi boost:

FTH in low s/c blower: 374 mph./2,743.9 m.

Switch low to high: 371 mph./3,658.5 m.

FTH in high s/c blower: 405 mph./6,158.5 m.

 

Speed +25 psi boost:

FTH in low s/c blower: 374 mph./853.7 m.

Switch low to high: 387 mph./2,743.9 m.

FTH in high s/c blower: 409 mph./4,268.3 m.

 

Climb +18 psi boost:

FTH in low s/c blower: 4,610 fpm./1,951.2 m.

Switch low to high: 3,960 fpm./3,353.7 m.

FTH in high s/c blower: 4,010 fpm./5,304.9 m.

 

Climb +25 psi boost:

FTH in low s/c blower: 5,580 fpm./S.L.

Switch low to high: 5,080 fpm./1,951.2 m.

FTH in high s/c blower: 5,100 fpm./3,353.7 m. 

 

Combat Weight: 7,770 lbs.

 

Maximum Engine Power: 1,720 hp.@ +18 psi and 1,940 hp.@ +25 psi

 

Wing Loading (with clipped wings): 33.64-lbs./sq.ft.

 

Power Loading: 4.517+(4.005+)lbs./hp.

 

Armament: Not given but my sources say it would have been 2 x 20mm + 4 x 0.303 or 4 x 20 mm.

 

 

 

 

Report: R.A.A.F. Headquarters, Directorate of Technical Services, Special Duties and Performance Flight, Spitfire Mk.VIII No. JF.934 with a Merlin 66 operating at +18 psi.

 

Altitude.Speed/Climb

Meters..mph/fpm/minutes to altitude

S.L.......330/4600/-----

.1,000..342/4600/--.8

.2,000..355/4470/-1.4

.3,000..363/3870/-2.25

.4,000..369/3270/-3.2

.5,000..382/4120/-4.0

.6,000..392/3645/-4.9

.7,000..393/3175/-5.9

.8,000..392/2700/-7.0

.9.000..389/2230/-8.35

10,000.381/1755/10.0

Feet------------------------------------------

.5,000..349/4600/-1.1

10,000.363/3840/-2.3

15,000.376/4145/-3.7

20,000.392/3600/-5.0

25,000.393/2880/-6.6 Maximum Speed.

30,000.389/2160/-8.6

35,000.368/1440/11.4

 

Speed:

FTH in low blower: 360.5 mph./2,301.8 m.

Switch from low to high: 363.5 mph./3,597.6 m.

FTH in high blower: 391 mph./5,640.2 m.

Climb:

Critical altitude in low blower: 4,600 fpm./1,768.3 m.

Switch low/high: 3,200/4,145 fpm./4,115.9 m. 

Critical altitude in high blower: 4,145 fpm./5,122 m.

 

Maximums: 393 mph.@ 25,000 ft. and 4,600 fpm.@ S.L.

 

NOTE: The report states that the speed of this aircraft was lower than those tested at Boscombe Down and that it was unusual for the maximum speed to be above the critical full throttle height.

 

Service Ceiling is listed as 41,000 ft.

 

Combat Weight: 7,690 lbs.

 

Wing Area: 231 sq.ft.? (clipped)

 

Wing Loading: 33.29 lbs./sq.ft.

 

Power Loading: 4.471-lbs./hp.

 

 

The following information on range is taken from the H.F.Mk.VIII (Merlin 70) Data Card dated 10/28/43. All performance figures except Maximum range with drop tank are at 7,340 lbs. The drop tank raised weight to 7,800 lbs.

 

Maximum (internal fuel): 660 mls./ 220 mph./ 20,000 ft./ 120 gallons of fuel.

 

Maximum (170 gal. drop tank): 1,530 mls./ 220 mph./ 20,000 ft./ 290 gallons of fuel.

 

Speed information from the same Data Card states: 396 mph./15,000 ft. and 416 mph./27,500 ft.

 

Service Ceiling (clean): 44,000 ft.

 

That is what I have been able to find on the Mk.VIII, Jeff


Edited by CORSNING, 26 July 2017 - 11:35 AM.


#2 CORSNING

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Posted 27 July 2017 - 06:55 PM

     The Supermarine Spitfire Mk.VIII was produced in basically three modes.

The Spitfire F.Mk.VIII fighter using the Merlin 61 or 63.

http://www.wwiiaircr..._VIII_F_ADS.jpg

 

     The Spitfire LF.Mk.VIII with a Merlin 66 thatthe supercharger was geared for

low level operations.

http://www.wwiiaircr...VIII_LF_ADS.jpg

 

The Spitfire HF. Mk.VIII where the supercharger was geared for high altitude

operations.

http://www.wwiiaircr...VIII_HF_ADS.jpg






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