1944: Tempest with 2-stage Griffon - the ideal fighter for RAF?
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davebender
1st Lieutenant
How did the Tempest perform at medium and high altitudes?
The Napier Sabre II-powered Tempest V was specialized for altitudes under 20,000 feet where it performed exceptionally (432 mph quoted here at 18.4K) and trailed off at altitudes higher than that, where Spits of both Merlin and Griffon type were expected to fill in but it still performed better than the Typhoon (which had the same engine) at all altitudes.
I think it would've probably performed better at high altitude with a Griffon 61/65 (not to mention be slightly more reliable) but I doubt it would've done anything better than the Spit Mk XIV in terms of maneuverability, top speed or time to climb to 30K.
wuzak
Captain
I was wondering if a C-series turbocharger would have fitted below the Sabre, behind the chin radiator.
Extend the radiator cowling to encompass the turbo and exhaust outlet.
Change the supercharger gearing so that low gear is for FTH at sea level, and high gear is as low gear as it was. That should give 50-100hp more in low gear just from reducing the power required to drive the supercharger.
C-series turbo should be able to provide sea level pressure to the Sabre until about 30,000ft. After turbo's critical altitude has been reached, switch to high gear and keep performance up at even higher altitudes.
You won't have the room for an air:air intercooler, so a liquid:air intercooler would need to be used. The radiator could, perhaps, be sited in teh wing leading edge, like the oil radiator on the Tempest II.
Not sure that the Tempest with Griffon 65 could mathc teh performance of the Spitfire XIV. Maybe in one or two areas, but not overall. The Tempest is a fair bit heavier (3000lbs?) than the XIV, and you wouldn't gain the benefit of the smaller forntal area of the Griffon.
Extend the radiator cowling to encompass the turbo and exhaust outlet.
Change the supercharger gearing so that low gear is for FTH at sea level, and high gear is as low gear as it was. That should give 50-100hp more in low gear just from reducing the power required to drive the supercharger.
C-series turbo should be able to provide sea level pressure to the Sabre until about 30,000ft. After turbo's critical altitude has been reached, switch to high gear and keep performance up at even higher altitudes.
You won't have the room for an air:air intercooler, so a liquid:air intercooler would need to be used. The radiator could, perhaps, be sited in teh wing leading edge, like the oil radiator on the Tempest II.
Not sure that the Tempest with Griffon 65 could mathc teh performance of the Spitfire XIV. Maybe in one or two areas, but not overall. The Tempest is a fair bit heavier (3000lbs?) than the XIV, and you wouldn't gain the benefit of the smaller forntal area of the Griffon.
davebender
1st Lieutenant
Per Wikipedia the Tempest carried 736 liters of internal fuel. Considerably better then a Spitfire.
Nothing beats a Spitfire for aerial performance (during WWII) but that doesn't matter if the Spitfire lacks adequate range / endurance.
Nothing beats a Spitfire for aerial performance (during WWII) but that doesn't matter if the Spitfire lacks adequate range / endurance.
vinnye
Senior Airman
Interesting idea - but with the other RAF options available, proven and reliable, maybe not worth the risk?
- Thread starter
- #7
Sure enough, a reliable Griffon vs. sometimes problematic Sabre could be a good idea?
Looking at the charts provided at Mike's site,the 2 stage Griffon has a notable edge in power vs. the Sabre IIA at higher altitudes (and at lower ones, if it's pushed up to 25 lbs/sq in using the 150 grade fuel), eg. 1600 hp achieved at cca 27300 ft vs. 22300 for the Sabre.
How fast it should be? Well, with +9 lbs/sq in boost (some 1850 HP), Tempest II was capable for 430-435 mph @ cca 18000 ft. At 26000 ft, it's some 1400 HP vs. 1700 HP for the Griffon; maybe another 10-15 mph for the Griffon Tempest? The low level performance should be lower vs. the Tempest V, unless the boost is upped to 21-25 lbs/sq in.
What does it have vs. the Spit XIV? All cannon armament, IIRC more rounds per cannon (140 vs 120?), 162 gals of internal fuel (with nose tank) vs. 112 gals, all around canopy. I'm not sure about drop tank carrying ability (2 x 90 gals vs 1 x 90?), so please chip in. Shortcoming is weight.
What does it have vs. LW, a question of a greater importance?
Looking at the charts provided at Mike's site,the 2 stage Griffon has a notable edge in power vs. the Sabre IIA at higher altitudes (and at lower ones, if it's pushed up to 25 lbs/sq in using the 150 grade fuel), eg. 1600 hp achieved at cca 27300 ft vs. 22300 for the Sabre.
How fast it should be? Well, with +9 lbs/sq in boost (some 1850 HP), Tempest II was capable for 430-435 mph @ cca 18000 ft. At 26000 ft, it's some 1400 HP vs. 1700 HP for the Griffon; maybe another 10-15 mph for the Griffon Tempest? The low level performance should be lower vs. the Tempest V, unless the boost is upped to 21-25 lbs/sq in.
What does it have vs. the Spit XIV? All cannon armament, IIRC more rounds per cannon (140 vs 120?), 162 gals of internal fuel (with nose tank) vs. 112 gals, all around canopy. I'm not sure about drop tank carrying ability (2 x 90 gals vs 1 x 90?), so please chip in. Shortcoming is weight.
What does it have vs. LW, a question of a greater importance?
bluezanzibar
Recruit
- 8
- Feb 26, 2012
There were plans to prototype the Griffon in the Tempest but the prototypes were never built.
From "British Secret Projects: Fighters Bombers 1935 to 1950 by Tony Buttler"
A formal contract was placed on June 17 (1942) for two prototypes fitted with Sabres, two with the Bristol Centaurus (down from six) and the last pair with Rolls-Royce Griffons. The Sabre IV prototype with wing leading edge radiators became the Tempest I while HM595 with the Sabre II was called the Tempest V prototype.
The Centaurus version became the Tempest II and the Griffon-powered aircraft the III and IV....
....The Tempest III and IV were never built. The Griffon version was begun as the P.I 016 and a drawing showing a Tempest V with the nose altered was attached to a letter from Camm to Rowe dated 10th April 1942. Camm explained that Hawker had for some time been considering an alternative engine for the Tempest and he felt this combination was a good one, particularly since they could use a Griffon 61 when it arrived without structural changes. The Griffon was lighter than the Sabre but slightly longer which left the balance of the aircraft practically unchanged.
Camm felt this project had great possibilities....
....The Tempest III with the Griffon lIB and Tempest IV with the Griffon 61 carried 140gal (637Iit) and 145gal (659Iit) of fuel respectively and offered times to 20,000ft (6,096m) of 9.0 and 8.3 minutes while their ceilings were 31,500ft and 40,000ft (9,60Im and 12, 192m).
It seems they were going to use the Griffon Tempest as a Hurricane replacement but it was thought the Tempest was too heavy for the Griffon, and in any case the Typhoon fitted that role perfectly.
From "British Secret Projects: Fighters Bombers 1935 to 1950 by Tony Buttler"
A formal contract was placed on June 17 (1942) for two prototypes fitted with Sabres, two with the Bristol Centaurus (down from six) and the last pair with Rolls-Royce Griffons. The Sabre IV prototype with wing leading edge radiators became the Tempest I while HM595 with the Sabre II was called the Tempest V prototype.
The Centaurus version became the Tempest II and the Griffon-powered aircraft the III and IV....
....The Tempest III and IV were never built. The Griffon version was begun as the P.I 016 and a drawing showing a Tempest V with the nose altered was attached to a letter from Camm to Rowe dated 10th April 1942. Camm explained that Hawker had for some time been considering an alternative engine for the Tempest and he felt this combination was a good one, particularly since they could use a Griffon 61 when it arrived without structural changes. The Griffon was lighter than the Sabre but slightly longer which left the balance of the aircraft practically unchanged.
Camm felt this project had great possibilities....
....The Tempest III with the Griffon lIB and Tempest IV with the Griffon 61 carried 140gal (637Iit) and 145gal (659Iit) of fuel respectively and offered times to 20,000ft (6,096m) of 9.0 and 8.3 minutes while their ceilings were 31,500ft and 40,000ft (9,60Im and 12, 192m).
It seems they were going to use the Griffon Tempest as a Hurricane replacement but it was thought the Tempest was too heavy for the Griffon, and in any case the Typhoon fitted that role perfectly.
Last edited:
- Thread starter
- #9
Thanks for the excerpts 
Judging by the time the Griffons were compared with Sabres, those engines were able to run at +18 lbs/sq in and +9 lbs/sq in, respectively. On those settings, Sabre was really a better performer; weight reliability being the downsides, together with performance at higher altitude. Once the Griffon was approved to run at +21 lbs/sq in boost (late 1943? - corrections welcomed), Sabre holds no cards.
With 150 grade fuel, the boosts were raised up to +25 and +11 lbs/sq in, respectively for Griffon Sabre; both engines receiving some stronger parts in order to withstand greater stress.
I do not agree that Typhoon was a perfect Hurricane's replacement. Hurri was a go-anywhere plane, from dusty sandy airstrips of African desert Russian steppes, throug snowy plains and humid SE Asia. Unlike the Typhoon.
Judging by the time the Griffons were compared with Sabres, those engines were able to run at +18 lbs/sq in and +9 lbs/sq in, respectively. On those settings, Sabre was really a better performer; weight reliability being the downsides, together with performance at higher altitude. Once the Griffon was approved to run at +21 lbs/sq in boost (late 1943? - corrections welcomed), Sabre holds no cards.
With 150 grade fuel, the boosts were raised up to +25 and +11 lbs/sq in, respectively for Griffon Sabre; both engines receiving some stronger parts in order to withstand greater stress.
I do not agree that Typhoon was a perfect Hurricane's replacement. Hurri was a go-anywhere plane, from dusty sandy airstrips of African desert Russian steppes, throug snowy plains and humid SE Asia. Unlike the Typhoon.
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