Marshall_Stack
Senior Airman
In Dean's book "Americas hundred thousand", he mentions that the RAF requested some light weight versions of the Mustang and one of them had a two stage Allison engine. Does anyone have more info on these engines?
Experimental Mustangs
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Colin1
Senior Master Sergeant
Hi Marshall
by lightweight, do you mean the versions after the P-51D?
I can find reference to the XP-51J
Two were built, 44-76027 and 44-76028 employing the Allison V-1710-119 rated at 1500hp driving a 3-bladed Aeroproducts screw. It had a maximum speed of 491mph at 27,400ft and a service ceiling of 43,700ft.
It doesn't mention anything about being requested by or shown to the British though.
by lightweight, do you mean the versions after the P-51D?
I can find reference to the XP-51J
Two were built, 44-76027 and 44-76028 employing the Allison V-1710-119 rated at 1500hp driving a 3-bladed Aeroproducts screw. It had a maximum speed of 491mph at 27,400ft and a service ceiling of 43,700ft.
It doesn't mention anything about being requested by or shown to the British though.
drgondog
Major
The XP-51F was one of five NA-105 airframes - collaboratively designed with Supermarine for weight reduction (and ultimate load factor reduction). The F, with the 1650-3 engine attained 466 mph at 28,000 feet with a takeoff weight of 7265 pounds with 180 gallons of fuel and ballast for guns/ammo.
Climb to 20,000 feet was 5 minutes. First flown Feb 1944, third one shipped to RAF in May 1944.
The XP-51G was FLOWN at a top speed of 495mph at 22,800 feet, ceiling was 46,000 feet and limited by fact it was not pressurized. It was a derivative of the same airframe as the XP-51F
It was powered by the Rolls Merlin 14 S.M - a development of the Mark 100.
The ultimate load factor for this lightweight prototype was 11.0 down from 12 on the B/D. Take off weight with 4 x .50s and 180 gallons of fuel was 7630 pounds. Time to 20,000 feet was 3.4 minutes... difference in weight primarily the more powerful Mk100 w/structure mods.
The P-51J was essentially the same as F/G except for Allison 1710-119 engine.
The result was combined with a 13 inch fuselage increase, an taller vertical fin, the 1650-9 to become the P-51H-1 production model ordered in April 1944.
This ship did in fact achieve 487mph w/o wing racks in interceptor mode during NAA Flight tests but was 20mph slower at Wright Pat in 1946. I haven't found the NAA flight tests to be able to compare differences between March 1945 NAA test and USAAF testing in 1946.
Source - Gruenhagen's "Mustang- the story of the P-51"
Colin1
Senior Master Sergeant
There were initially problems with the Allison V-1710-119s admittedly
but once they resolved them and got the -119 cleared for full power trials they did very well in the P-82E, yielding 465mph at 21,000ft and a ceiling of 40,000ft, which is still very respectable.
Marshall
they did supply the RAF with 3 P-51Fs but they were Packard Merlin-powered.
Colin1
Senior Master Sergeant
Sorry fella
I should have looked before I posted
drgondog
Major
Colin - My research shows that except for the basic rudder and other design changes )lower radiator cowl, etc) within the seven NA-105 (incl. NA-105A and NA-105B) airframes, there were three engines tested. The 1650-3, the Mk 100/SM 14 and the 1710-119.
NAA had agreed to provide two NA-105's (F's) and two NA-105A (G's) in return for five SM Mk100 derivatives plus the Rotol Props.
All five of the original NA -105 (incl 105A) airframes had been designed for the agreed SM 14's but delays on shipment forced the 1650-3 in the first three XP-51F's. The shipment arrived in time to install in XP-51F numbers three and four and became the P-51G prior to delivery to RAF
The flight tests achieveing the exceptional performance (speed, climb, ceiling) were all with the superb SM 14.
What I am not clear on is whether the original two XP-51F which had the 1650-3 was delivered to Boscombe Downs as FR409 (which I believe to be true, followed by two XP-51G with SM 14 as FR410). The first two were delivered to RAF in July 1944, the second two in Feb 1945 after NAA flew for six months.
I do know ships 6 and 7 (NAA-105B) was built with Allison 1710-119 as XP-51J's
Colin1
Senior Master Sergeant
I'll buy that dr
your source seems to cover that in far more detail than mine
your source seems to cover that in far more detail than mine
Air Enthusiast No 95 Sept/Oct 2001 - P-51 Variants.
In their efforts to produce a lightweight Mustang North American carried out extensive re-design of the basic P-51 airframe but installed the same V-1650-7. This came about after NAA had submitted proposals in January 1943 to the USAAF for a fighter akin to the P-51s then being built, but designed to British load factors, which would result in a lightweight high performance aircraft. The revised design provided a lower ultimate load factor than standard, designated NA105. Two prototypes were ordered as XP-51Fs, but this contract was updated in June 1943 to cover five XP-51Fs powered by V-1650-3s. In the event the last two would subsequently be converted to XP-51Gs with Rolls-Royce Merlin 145Ms, which would be acquired from Britain under a reverse Lend-Lease agreement.
A Technical Command request to procure 25 P-5 1Fs for service testing was turned down, it being decided that prototype trials should be undertaken before any quantity production was started. Britain requested two of the lightweight fighters be allocated for RAF evaluation and received one XP-51F and one XP-51G. The P-51E designation was not allotted to any Mustang variant therefore first of the experimental lightweight Mustangs was the XP-51F. This featured a simplified structure and deletion of some equipment, as well as the use of plastic and other light materials. A thinner wing of more advanced low-drag section was fitted in which the familiar' crank' of previous Mustangs was missing, smaller wheels were attached to a simplified landing gear, an elongated 'bubble' canopy fitted to further reduce drag and the bulky oil cooler replaced by a shallow heat exchanger. The fuel system was designed around two 105 US gallon (397 litre) wing tanks, a three-blade hollow-steel propeller by Aeroproducts was fitted and four instead of six machine-guns installed. About one ton (1.016 tonne) in weight was saved, which reduced the XP-51F down to a loaded weight of 9,060lb (4,109kg). A maximum speed of 466mph (750km/h) was recorded, but only three were built (43-43332 to -43334). The first XP-51F flew on February 14, 1944, the second and third on May 20 and 22 respectively. The latter machine was shipped to Britain on June 30, 1944 and allotted the serial FR409.
Designation XP-51G was given to the remaining two lightweight Mustangs (43-43335 and -43336) the first of which made its initial flight on August 9,1944, the second on November 14. This second machine was shipped to Britain in February 1945 and serialled FR410. The XP-51G possessed a similar airframe to the previous 'F variant, but had the 1,9lOhp (1,424kW) Merlin 145M driving a five bladed Rotol propeller, With a gross weight of 8,8791b (4,027.5kg) the XP-51G achieved a top speed of 472mph (759.5kmjh). One other pair of lightweight Mustangs was ordered as XP-51Js (44-76027-76028) to be powered by the 1,720hp (1,283kW) at 20, 700ft (6,310m) V-1710119 producing 1,5OOhp (1,119kW) for take-off and 1,720hp (1,283kW) with water injection at 20,700ft (6,309m). Air intake for the carburettor on the XP-51J was in incorporated in the ventral radiator.
The first machine (44-76027) flew on April 23, 1945, but full power operation was not possible due to the engine not being sufficiently developed. This aircraft was loaned to Allison for engine development purposes, while the second machine (44-76028) was not flown and went to provide spares for the first aircraft. Weighing only 6,030lb (2,735kg) empty and 7,550lb (3,424kg) normally loaded the XP-51J was estimated to have a top speed of 491mph (790kmjh) at 27,40Oft (8,351m), but this figure was never attained under test conditions.
Neither the XP-51G or XP-5J reached production status, but they provided a wealth of data and experience for use in North American's next production variant, the Mustang P-51H. This was powered by a V-1650-9, which had a war emergency rating (with water injection) of 2,218hp (1,654kW) at 10,200ft (3,109m). With a top speed of 487mph (784kmjh) at 25,000ft (7,620m) the P-51H was thus the fastest Mustang variant to enter USAAF service. Generally similar to the XP-51F the P-51H differed in having a shorter 'bubble' cockpit canopy, a four-bladed Aeroproducts propeller, a dorsal extension to the tail fin, a taller fin and rudder (from the 13th production machine onwards), an overall length increase to 33ft 4in (10.1m) and wing tanks supplemented by a 50 US gallon (189 litre) fuselage tank resulting in a total internal fuel capacity of 255 US gallons (965 litres). With the addition of two 75 US gallon (284 litre) external drop tanks, range of the P-51H could be extended from 1,000 miles (1,609km) to 1,530 miles (2,462km).
This variant retained the XP-51F's shallow carburettor air intake, modified cowling and integral engine mounting, low-drag wing, revised landing gear with smaller wheels and disc brakes, the latter modification allowing a straight instead of 'cranked' wing leading edge, which had been a feature on all previous production models of the Mustang. The armament was unchanged, alternative gun installations being four or six 0.5in (12.7mm) with 1,600 rounds or 1,880 rounds respectively, while external ordnance could comprise two 500lb (227kg), or two 1,000lb (4S4kg) bombs, or six Sin (127mm) High-Velocity rockets on underwing launchers. Compared to the P-51D there was a 40% saving in weight for the P-51H, a factor which greatly helped to enhance the latter's performance. One P-S1H (KN987) arrived in the UK for RAF evaluation, but this variant was not adopted for service.
Initial flight of the first P-51H-1-NA (44-64160) was on February 3, 1945, and it was followed by a further 19 before 280 P-51H-S-NA and 2SS-10-NA were produced, these batches featuring only minor equipment updates and other changes. In fact these 555 machines were part of an order for 2,000 P-51Hs, but VJ-Day resulted in cancellation of the remainder. An order for 1,700 P-51Ls, which would have been similar except for an up rated V16S0-11, was also cancelled.
The Dallas-built version of the P-51H was designated P-51M, but of 1,628 ordered only one (45-11743) was completed before the war with Japan ended. Too late to participate in the European theatre of operations, the P-51H re-equipped a number of USAAF fighter groups in the Pacific area and took part in the final stages of the war against Japan.
After World War Two many war surplus Mustangs became available to air arms worldwide, but although the P-51H was the lightest and fastest as we have seen, it was the plentiful P-51Ds and P-51Ks that were mostly snapped up by the world's smaller air forces, those not having at least a squadron of Mustangs on charge being few and far between. A number of machines were converted by different companies as tandem two-seaters for use in the special liaison or training role. From the 'second level' use came the large quantity of machines today flown as 'warbirds' or air racers.
In their efforts to produce a lightweight Mustang North American carried out extensive re-design of the basic P-51 airframe but installed the same V-1650-7. This came about after NAA had submitted proposals in January 1943 to the USAAF for a fighter akin to the P-51s then being built, but designed to British load factors, which would result in a lightweight high performance aircraft. The revised design provided a lower ultimate load factor than standard, designated NA105. Two prototypes were ordered as XP-51Fs, but this contract was updated in June 1943 to cover five XP-51Fs powered by V-1650-3s. In the event the last two would subsequently be converted to XP-51Gs with Rolls-Royce Merlin 145Ms, which would be acquired from Britain under a reverse Lend-Lease agreement.
A Technical Command request to procure 25 P-5 1Fs for service testing was turned down, it being decided that prototype trials should be undertaken before any quantity production was started. Britain requested two of the lightweight fighters be allocated for RAF evaluation and received one XP-51F and one XP-51G. The P-51E designation was not allotted to any Mustang variant therefore first of the experimental lightweight Mustangs was the XP-51F. This featured a simplified structure and deletion of some equipment, as well as the use of plastic and other light materials. A thinner wing of more advanced low-drag section was fitted in which the familiar' crank' of previous Mustangs was missing, smaller wheels were attached to a simplified landing gear, an elongated 'bubble' canopy fitted to further reduce drag and the bulky oil cooler replaced by a shallow heat exchanger. The fuel system was designed around two 105 US gallon (397 litre) wing tanks, a three-blade hollow-steel propeller by Aeroproducts was fitted and four instead of six machine-guns installed. About one ton (1.016 tonne) in weight was saved, which reduced the XP-51F down to a loaded weight of 9,060lb (4,109kg). A maximum speed of 466mph (750km/h) was recorded, but only three were built (43-43332 to -43334). The first XP-51F flew on February 14, 1944, the second and third on May 20 and 22 respectively. The latter machine was shipped to Britain on June 30, 1944 and allotted the serial FR409.
Designation XP-51G was given to the remaining two lightweight Mustangs (43-43335 and -43336) the first of which made its initial flight on August 9,1944, the second on November 14. This second machine was shipped to Britain in February 1945 and serialled FR410. The XP-51G possessed a similar airframe to the previous 'F variant, but had the 1,9lOhp (1,424kW) Merlin 145M driving a five bladed Rotol propeller, With a gross weight of 8,8791b (4,027.5kg) the XP-51G achieved a top speed of 472mph (759.5kmjh). One other pair of lightweight Mustangs was ordered as XP-51Js (44-76027-76028) to be powered by the 1,720hp (1,283kW) at 20, 700ft (6,310m) V-1710119 producing 1,5OOhp (1,119kW) for take-off and 1,720hp (1,283kW) with water injection at 20,700ft (6,309m). Air intake for the carburettor on the XP-51J was in incorporated in the ventral radiator.
The first machine (44-76027) flew on April 23, 1945, but full power operation was not possible due to the engine not being sufficiently developed. This aircraft was loaned to Allison for engine development purposes, while the second machine (44-76028) was not flown and went to provide spares for the first aircraft. Weighing only 6,030lb (2,735kg) empty and 7,550lb (3,424kg) normally loaded the XP-51J was estimated to have a top speed of 491mph (790kmjh) at 27,40Oft (8,351m), but this figure was never attained under test conditions.
Neither the XP-51G or XP-5J reached production status, but they provided a wealth of data and experience for use in North American's next production variant, the Mustang P-51H. This was powered by a V-1650-9, which had a war emergency rating (with water injection) of 2,218hp (1,654kW) at 10,200ft (3,109m). With a top speed of 487mph (784kmjh) at 25,000ft (7,620m) the P-51H was thus the fastest Mustang variant to enter USAAF service. Generally similar to the XP-51F the P-51H differed in having a shorter 'bubble' cockpit canopy, a four-bladed Aeroproducts propeller, a dorsal extension to the tail fin, a taller fin and rudder (from the 13th production machine onwards), an overall length increase to 33ft 4in (10.1m) and wing tanks supplemented by a 50 US gallon (189 litre) fuselage tank resulting in a total internal fuel capacity of 255 US gallons (965 litres). With the addition of two 75 US gallon (284 litre) external drop tanks, range of the P-51H could be extended from 1,000 miles (1,609km) to 1,530 miles (2,462km).
This variant retained the XP-51F's shallow carburettor air intake, modified cowling and integral engine mounting, low-drag wing, revised landing gear with smaller wheels and disc brakes, the latter modification allowing a straight instead of 'cranked' wing leading edge, which had been a feature on all previous production models of the Mustang. The armament was unchanged, alternative gun installations being four or six 0.5in (12.7mm) with 1,600 rounds or 1,880 rounds respectively, while external ordnance could comprise two 500lb (227kg), or two 1,000lb (4S4kg) bombs, or six Sin (127mm) High-Velocity rockets on underwing launchers. Compared to the P-51D there was a 40% saving in weight for the P-51H, a factor which greatly helped to enhance the latter's performance. One P-S1H (KN987) arrived in the UK for RAF evaluation, but this variant was not adopted for service.
Initial flight of the first P-51H-1-NA (44-64160) was on February 3, 1945, and it was followed by a further 19 before 280 P-51H-S-NA and 2SS-10-NA were produced, these batches featuring only minor equipment updates and other changes. In fact these 555 machines were part of an order for 2,000 P-51Hs, but VJ-Day resulted in cancellation of the remainder. An order for 1,700 P-51Ls, which would have been similar except for an up rated V16S0-11, was also cancelled.
The Dallas-built version of the P-51H was designated P-51M, but of 1,628 ordered only one (45-11743) was completed before the war with Japan ended. Too late to participate in the European theatre of operations, the P-51H re-equipped a number of USAAF fighter groups in the Pacific area and took part in the final stages of the war against Japan.
After World War Two many war surplus Mustangs became available to air arms worldwide, but although the P-51H was the lightest and fastest as we have seen, it was the plentiful P-51Ds and P-51Ks that were mostly snapped up by the world's smaller air forces, those not having at least a squadron of Mustangs on charge being few and far between. A number of machines were converted by different companies as tandem two-seaters for use in the special liaison or training role. From the 'second level' use came the large quantity of machines today flown as 'warbirds' or air racers.
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