1941: the best airframe for a single engined fighter

[jim]

Mr Tomo Pauk Mr Dave bender
My point is that P 51 airframe was too heavy for the Alison and the merlin and at the same time could not recieve a bigger engine. Only superior fuels and extreme overboost ( amazing in my opinion but that s another discussion) kept it competitive at mid/low altitute and at high altitude the lack og 2 stage supercharges in german aircrafts. But these things had nothing to do with the excellence of its airframe.
Imagine that RAF in early 42 had the P51 with the Merlin 45 in place of Spit V . What results woulde get against Bf 109F4 and Fw190 A3/4?
I repeat P51 was excellent, top escort fighter (along late p38s) but during all its carrer i could see better dogfight/air superiority airframes,
Many german pilots had this opinion too

 

[zoomar]

Why no love for the Spit? Was great initially, and accepted increasingly powerful engines and redesigns until the end of the war while maintaining flying qualities, something that you really can't say for the Bf-109.

And, if we are talking only about airframe, how about the P-39? There was probably not a sleeker design in 1939, plus the tricycle gear made it a great ground handler.

 

[tomo pauk]

I can readily agree that P-51 was not a lightest airframe, and that was somewhat restricting the rate of climb. The weight was a trade off - it was offering some 50-100% more internal fuel than other fighters with V-12 engines. The 'superior fuel' was also used in Fw-190 (the C3), so no point to draw that as an argument IMO.
Merlins have had the supercharger sets on their side, DBs, Jumos and radials have had the swept volume (mostly) water or excess fuel injection on their. Anybody had something, making the best mix was the key for success. The basic P-51 airframe entered the fray in 1942, and as such was competitive even in 1945 - I'd say it was a great airframe.

If any Spitfire gets bad press, that would be the Mk. V, and the year is the 1942. The P-51 of 1942 (Mustang I in RAF service) was able to fly 20-25 mph faster on the (for plenty of people) lousy Allison. The P-51A (Mustang II) was about as fast, but useful up to maybe 25000 ft (max speed achieved at 17500 ft). The Merlin 45 adds another 4000 ft to the full throttle height vs. the P-51A's engine, so the P-51 is competitive even higher up, with maybe 410 mph this time. Or we can install the Merlin XX, or 24, or 28, to add altitude flexibility.
So we have a plane that makes at least 30 mph more than Spit V, and has no problems carrying 4 cannons (as historically in Mustang Ia). I'd say it would make a good asset for any air force of 1942.
Would it be a good dogfighter? I don't know, but I know that low level Mustang Is racked up many kills vs. LW opposition, while flying for Army cooperation units.
As an air superiority fighter? P-51s managed to fight survive in German-held airspace, even more actually.

BTW, the DB-605AS has had the the same power high up as the Merlins from 1943-44. The Bf-109 with AS engine was some 20 km/h slower than P-51 of the same era (mid 1944); P-51 was able to fly 500 miles, make it's presence felt, and return home. Unlike the 109G-6/AS (or any other).

As for different engines: after single stage V-1710, it received Packard Merlin, and a prototype was flown with two stage V-1710 (substantially longer than P. Merlin, let alone the single stage V-1710), so I see no issues there. As for Griffon as a perceived next-gen engine, the British production was small (only Spitfires were fling it war time), and there was no US production of those to make re-engining effort plausible.
The post war racers have had the Griffon installed; it was shorter than 2-stage Merlin IIRC, so no I see no problems there.

 

[davebender]

That's because the P-51 airframe was relatively large. IMO that aircraft was begging to be powered by a RR Griffon engine.

 

[Siegfried]

. The 'superior fuel' was also used in Fw-190 (the C3), so no point to draw that as an argument IMO. .

Late war C3 was somewhere between 96/130 to 100/130 while the allied 100/130 fuel was closer to 104/130. As the Germans started ramping up C3 production, only to see it interrupted by the oil campaigns of early 1944 the allies started moving to 100/150 fuel. Early in the war C3 was closer to 94/115.

The allies maintained a substantial fuel advantage worth about 15%-20% in power.

Very few FW 190D-9, if any ever opperated of C3 fuel. The DB605ASM engine I think was still inferior to the Merlin at altitude. The DB605ASC and ASB with their higher compression ratios however were more potent.

 

[davebender]

DB605ASM engine I think was still inferior to the Merlin at altitude. The DB605ASC and ASB with their higher compression ratios however were more potent.

How did the late war DB605D perform at high altitude?

 

[Shortround6]

Why no love for the Spit? Was great initially, and accepted increasingly powerful engines and redesigns until the end of the war while maintaining flying qualities, something that you really can't say for the Bf-109.

And, if we are talking only about airframe, how about the P-39? There was probably not a sleeker design in 1939, plus the tricycle gear made it a great ground handler.

The problem with being a sleek as the P-39 was that there wasn't enough room inside for a decent amount of fuel. It is all well and good to be the toughest guy on a small, short block but if you can't cross the street to get into the fight ( or climb above the lower floors) the title of "best" all around is out of of reach.

Now if somebody wants to start a thread on best Fighter with under 120 gallons of fuel

 

[davebender]

It is all well and good to be the toughest guy on a small, short block but if you can't cross the street to get into the fight ( or climb above the lower floors) the title of "best" all around is out of of reach.

I agree.

To some extent the Spitfire and Me-109 had a similiar problem. Outstanding aerial performance but low endurance.

 

[tomo pauk]

Late war C3 was somewhere between 96/130 to 100/130 while the allied 100/130 fuel was closer to 104/130. As the Germans started ramping up C3 production, only to see it interrupted by the oil campaigns of early 1944 the allies started moving to 100/150 fuel. Early in the war C3 was closer to 94/115.

The allies maintained a substantial fuel advantage worth about 15%-20% in power.

Very few FW 190D-9, if any ever opperated of C3 fuel. The DB605ASM engine I think was still inferior to the Merlin at altitude. The DB605ASC and ASB with their higher compression ratios however were more potent.

How did the late war DB605D perform at high altitude?

DB-605AS was making about the same power as Merlin 66 high up. The ASM, via usage of ADI (MW 50 here) was managing to compete at all altitudes (at SL 1800 PS, at 6400m 1500 PS). The D series have slightly more PS (maybe 50 above 5000m). Note the two values for the 2-stage DB-605L, really a great engine, but another example of 'too little, too late'.
I did not draw the 'knick' under the full throttle height (for 2nd gear) of the Merlin 66, where the 605s have advantage due to construction of it's supercharger (infinite 'number' of gears, vs. two gears of Merlin); the 'low point' of the Merlin is at some 3200m, 1450 HP. The ASM, DB and DC are far better there (only if they use the MW 50 there about, delivering some 1650-1700 HP at 3200m), but not the AS.

 

[tomo pauk]

The problem with being a sleek as the P-39 was that there wasn't enough room inside for a decent amount of fuel. It is all well and good to be the toughest guy on a small, short block but if you can't cross the street to get into the fight ( or climb above the lower floors) the title of "best" all around is out of of reach.

Now if somebody wants to start a thread on best Fighter with under 120 gallons of fuel

Well put. Bolded part is pure gold

 

[drgondog]

Mr Tomo Pauk Mr Dave bender
My point is that P 51 airframe was too heavy for the Alison and the merlin and at the same time could not recieve a bigger engine. Only superior fuels and extreme overboost ( amazing in my opinion but that s another discussion) kept it competitive at mid/low altitute and at high altitude the lack og 2 stage supercharges in german aircrafts. But these things had nothing to do with the excellence of its airframe.

It is an interesting argument to start by assigning 'too heavy' to the P-51 Airframe. We might consider the relative weights of the F-22 versus MiG 29, F-15 and ask the same question. Or compare the heavy P-51 to the F4U or P-47 or P-38?

I can't speak for your frame of reference but to me an 'excellent' airframe is one that grows over time with respect to performance and mission roles with essentially great aerodynamics, fuel capacity, engine power, armament, etc - and a bonus is remain competitive with newer versions of the opponents best products. A further bonus is the economics of the design with respect to manufacturing.

Imagine that RAF in early 42 had the P51 with the Merlin 45 in place of Spit V . What results woulde get against Bf 109F4 and Fw190 A3/4?
I repeat P51 was excellent, top escort fighter (along late p38s) but during all its carrer i could see better dogfight/air superiority airframes,
Many german pilots had this opinion too

I wonder which airframes the German pilots had in mind as better air superiority airframes? The ultimate questions dwindle down to 'point superiority-short leash' airframes for interception and 'long distance air superiority-long leash' for dominance over the enemy's airspace. For the latter your choices kind of narrow down to A6M, F6F, F4U, P-47 and P-38 for initial selection - and pass over Bf 110 and all LW/VVS/GB fighter derivatives?

If the Bf 109 and FW 190 are point superiority, defined as over your own airspace and say 200 miles into enemy airspace, the next question is did they achieve air superiority against the heavier, longer range aircraft cited above? Were they able to achieve 'break even results' when the odds were reasonably equal over their home airspace?

How did lower gross weight affect the outcome?

 

[davparlr]

What was the accelaration of early P-51s? Their power loading?

Remember it is not horsepower to weight that determines acceleration but rather available horsepower to weight. Take for instance a P-51 (Allison) and a Bf-109F flying at SL at 325 mph. The power loading is in favor of the Bf-109F because it is lighter and both engines are capable of about 1150 hp. However, the max speed of the Bf-109F at SL is 325 mph while the P-51 max speed is 344 mph. At 325 the lighter Bf-109F is expending all of its power just to maintain airspeed and has zero available to accelerate. The heavier P-51, however is not expending all of it power to maintain airspeed and has hp available to accelerate to 344 mph. So at every airspeed, the Bf-109F is expending more engine power just to maintain airspeed than the P-51 which will have more available hp. Will this always mean the P-51 will out accelerate the Bf-109F at every airspeed, I don't think so, but you need to know the using hp at the desired airspeed to determine acceleration issues. The P-51 will certainly out accelerate the Bf-109F at 325 mph!

Some stats
Bf-109F 1150 hp 324 mph at SL
Fw-190A-3 1730 hp 335 mph at SL
Spit II 1090 hp 290 mph at SL
P-51 (Allison) 1150 hp 344 mph at SL

An excellent example of airframe efficiency.

their rate of climb? Their manouverability?

In 1944, the P-51B with 300 less hp is equivalent to the vaunted Fw-190D-9 in airspeed and climb up to 20k where it then just out performs the D-9. The slightly heavier P-51D is close behind.

What would be P51D without superior fuels given the inability to accept bigger engine?

This seems to be a strange comment. Where would the Bf-109 be without MW-50. The P-51 did not use water injection until the P-51H came along. By the way, the dash 9 engine in the P-51H with water generated over 2200 hp, which is quite favorably compared to the Spit XIV, Tempest, and any Fw-190, even the D-9. The Merlin engine was three hundred pounds lighter than the Griffon, seven hundred pounds lighter than the Napier, and four hundred pound less than the Jumo 213.

I accept the brilliance of the design as superb escort fighter

Typically not debatable

but i see shortcomings as far as air superiority fighter. I honestly cannot see how P51 airfame defeats Bf109F-4

The F-4 was significantly outclassed in airspeed (50 mph at SL) and matched in climb by the P-51B pulling 67" Hg. And, apparently debatably it would out turn the Bf.

, or P51D defeats bf109K-4 on 1v1 combat given same quality of fuels and same building quality and same quality of pilots.

This is a different story. The K was a high performance point intercepter and was a formidable opponent to the B or D, but it had limited endurance.

Or against Ki 84, Fiat G56, Spitfire XIV, Tempest,Fw190A-3/4,etc

None of these planes could fly the distance the P-51 did except for the Ki-84 which was not as fast. The G56 was way too slow. Speed is energy, energy is life not maneuverability.

My point is that P 51 airframe was too heavy for the Alison and the merlin and at the same time could not recieve a bigger engine.

Did anyone try?

Only superior fuels and extreme overboost ( amazing in my opinion but that s another discussion) kept it competitive at mid/low altitute and at high altitude the lack og 2 stage supercharges in german aircrafts. But these things had nothing to do with the excellence of its airframe.

The P-51 was a superbly designed airframe.

Imagine that RAF in early 42 had the P51 with the Merlin 45 in place of Spit V . What results woulde get against Bf 109F4 and Fw190 A3/4?

For one thing it would have been 30 mph faster than any of them and control when and where to fight and could loiter much longer and chase the enemy all the way home.

I repeat P51 was excellent, top escort fighter (along late p38s) but during all its carrer i could see better dogfight/air superiority airframes,

Yes but they weren't needed do to range and the P-51 was and could out fly the enemy over its own territory.

Many german pilots had this opinion too

P-51 pilot experts testify just to the opposite.


View: https://www.youtube.com/watch?v=aB6ka32iTbU

Surprise, surprise.

 

[davebender]

The P-51B and P-51D had extreme range to meet a requirement unique to the U.S. Army Air Force. Other nations aren't going to build such a flying fuel tank if it isn't needed. Just as the U.S.A.A.F. wasn't going to arm and armor the P-51 for shooting down hordes of enemy bombers without a need to do so.

 

[tomo pauk]

Japanese planes have had the extreme range cašabilities, from beginning of the ww2. RAF was trying to increase ranges of their Spitfires, 1st by installing 29 imp gal fuel rear tank, later going to the circa 70 gals. Spitfire from 1942 was able to fly with a dropable 175 imp gals fuel tank - about as much as Merlin Mustangs had under wings with 2 x 108 us gals. Soviets were trying to boost the range of their Yaks, 1st with Yak-9D ('distantsnoy' - literary 'for distances'), later with Yak-9DD ('dalyno distantsnoy' - for great distances), so they saw need for great combat ranges, too. Ta-152 was to feature wing root tanks, Bf-109H too.

IMO the Japanese were 1st to foresaw the need for fighters with legs, no wonder since the vast areas of Asia/Pacific were to be the hunting area for those.

 

[Shortround6]

The initial P-51 wasn't really a flying fuel tank. Especially compared to other US fighters. 180 US gallons in protected wing tanks is actually fairly normal for a US fighter if looked at historically. Given the size of the US we needed longer ranged fighters just to move around the country on deployment let alone combat missions.

The P-36 carried 155-160 gallons in unprotected tanks in 1938. The P-40 carried about the same and went for as much as 200 in unprotected tanks before the self-sealing tanks were adopted. The early P-38s carried 400 gallons.
The P-51 just allowed the carriage of the "normal" desired fuel capacity in protected tanks.
The other part of the greater range came from the low drag airframe, much like a 109F has a longer range than a 109E using the same amount of fuel or the much ballyhooed He 100 had such a long range on the same amount of fuel as the 109E.

Since this thread is about the BEST AIRFRAME, the adaptability of the airframe needs to be considered. The P-51 not only had the range thing going for it, it had the ability to be armed as a bomber destroyer if that was what was wanted. It also had the ability to be used as a fair fighter bomber with a much higher payload ( especially considering the radius it carry the bombs over) than many of the other planes.

 

[parsifal]

Yes, the RAF would have loved to have a P-51 or equivalent in 1942, to extend the air superiority they had already gained (at such hig price) over Britain, the Channel and the channel coast in 1941-2. The Luftwaffe either refused battle except under the most favourable circumstances, or withdrew out of the range of FC. If FC had had a long range fighter like the P-51 in 1942, they could have finished the LW off in the west.

In 1943 when the P-51 began to be supplied as LL, the RAF could not get enough of them. There were no serious complaints about the type from any in the CW that used them.

What we are seeing here is the classic formula these guys always use....mix a little truth with a load of codswallop to jazz up the brew, and thereby increase its potency. that way more people will believe the basic lie

 

[drgondog]

Parsifal - have you thought about the effect you have on tender ears when you 'tippy toe' around the point?

 

[davebender]

That was a naval requirement. The IJN needed a long range escort for long range Nell and Betty maritime attack aircraft.

 

[pbfoot]

IMHO you have to be on drugs if you think that Fighter Command won the Channel War 42 -43. I do believe who ever believes that the Channel War was a done thing or allied victory is few pages short of a book.

 

[drgondog]

The P-51B and P-51D had extreme range to meet a requirement unique to the U.S. Army Air Force. Other nations aren't going to build such a flying fuel tank if it isn't needed. Just as the U.S.A.A.F. wasn't going to arm and armor the P-51 for shooting down hordes of enemy bombers without a need to do so.

Dave - it would be better to stipulate "US" because the USN certainly had long range requirements to extend escorted bomber footprint from carriers.

The USAAF contemplated the P-38 with 1x20 and 4x50 as more than enough for interceptor work and certainly had 4x20 to fall back on for bomber interceptor role - ditto P-47 8x50s as well as F6F and F4U standard and optional armament. The P-51B w/4x50 was a little light for He 177 and Do 217 but didn't have too much trouble taking them down one on one. Other than the 'horde' issue the US was well prepared to take on LW/Japanese/Italian bombers throughout the war until the Ar234.

The P-51B was just as formidable to the Do 217 as the 109 was to the B-17. I wouldn't make that claim versus the FW 190!