p51 vs p47

[drgondog]

The flaps worked quite well to increase CLmax (CL= lift coeficient) on the P-51's otherwise low-lift wing.

There was a definite airspeed limitation on deployment of flaps on a 51. The P-38 manuevering flaps on the other hand were designed (for late J and L) for combat speeds.

I don't know where the comes from (probably due to the spifire) but the only thing the eliptical shape does is increase lift to drag ratio, in a full eliptical wing (like the Spit) this also makes for violent stalls, but the straight leading edge of the P-47 mitigates this iirc. (fairly gentle stalls, moreso than the P-51 as well)

The 47 had a gentler stall in a high G turn as it is easy to spin a 51 at stall. Having said that both power on and power off stalls in level flight are very gentle in a 51.

Power doesn't mean much on is own. I's when you put weight into the equation that you can get a comparable figure. Hell the P-38L had over 3500 hp in WEP! Plus the P-47M/N had the R-2800-57C capable of 2,800 hp in WEP up to 32,000 ft. The R-2800-59/63 of the P-47D was cleared for 2,600 hp with 100/150 avgas at 70" HG. (but 70" was only good up to ~23,500 ft) with this a late model P-47D could manage 444 mph at critical altitude. Some may have been tuned up to 2,700+ hp as well.

Drag is an even bigger factor KK. That is why a 51 which didn't have as good a power to weight ratio as a P-38 was nevertheless faster and flew much farther on same fuel load.

But bact to power-loading (weight/power) or (what I prefer) power/weight: the late P-47D weighed 14,600 lbs (clean, full internal fuel), the P-51D in the same configuration was 10,100 lbs. The P-47D had 2,600 hp, the P-51 had ~1,700 hp. So: P-47D: .178 hp/lb P-51D: .168 hp/lb. P-47 is ~6% better. But this is just one simplified comparison.

Back to drag. The 47 compared speed wise above 30,000 feet because the R-2800 blower was more efficient than the Merlin above 25,000 feet (for the -7)

 

[kool kitty89]

THat post is 7 months old Bill. I've learned a few more things from you guys since then. (and my reading on the subject)
Thanks for adding it in though.


On the stall issue, I think a distinction should be made between a gentle stall and a well warned stall. In the case of the P-47 (or P-38 ) I believe the stall its self was quite gentle and easy to recover from. (with spins very unlikely, or nearly impossible in the P-38's case, unless the pilot intended to spin) With the P-51, there was a lot of warning but the stall was rather violent. (I believe the Spitfire was somewhat similar -both being pretty snappy-)


Also, in the case of power, at the full 70" WEP had a critical altitude (for the R-2800-63 or -59) was only ~24,000 ft. (though I'm not sure how the V-1650-7's power curves compare with 100/150 grade)


I also am not sure how the airfoil properties wouls compare, as I have no information for the P-47's wing other than it used the Seversky S-3 airfoil.


I agree that P-51 was a much cleaner plane. (even with size taken into account) The XP-47J's cowling arrangement would have substantially improved this for the P-47, but that's another issue.

 

[drgondog]

THat post is 7 months old Bill. I've learned a few more things from you guys since then. (and my reading on the subject)
Thanks for adding it in though.


On the stall issue, I think a distinction should be made between a gentle stall and a well warned stall. In the case of the P-47 (or P-38 ) I believe the stall its self was quite gentle and easy to recover from. (with spins very unlikely, or nearly impossible in the P-38's case, unless the pilot intended to spin) With the P-51, there was a lot of warning but the stall was rather violent. (I believe the Spitfire was somewhat similar -both being pretty snappy-)

All you say about 51 and Spit for High G turn is true. Good warning (time to release a little pressure on stick and rudder).. In level flight in steep climb, same good warning but the stall wasn't violent.. sometimes it would stall with wings level, sometimes fall off on one wing but pretty gentle.


Also, in the case of power, at the full 70" WEP had a critical altitude (for the R-2800-63 or -59) was only ~24,000 ft. (though I'm not sure how the V-1650-7's power curves compare with 100/150 grade)


I also am not sure how the airfoil properties wouls compare, as I have no information for the P-47's wing other than it used the Seversky S-3 airfoil.

Simply - more drag for both the 38 and 47 wing as well as fuselage parasite drag


I agree that P-51 was a much cleaner plane. (even with size taken into account) The XP-47J's cowling arrangement would have substantially improved this for the P-47, but that's another issue.

True.

 

[Timppa]

As, this poll is still alive, P-51. Considered the best by most German and Japanese opponents.
P-47 is close second, lower total loss rate AFAIK.

 

[Burmese Bandit]

Well, if i was meeting my twin brother in a battle at equal attitude, I would choose a P-51, climb my ass off till I was 2000 feet above him, then dive down on him!

 

[HoHun]

Hi Timppa,

>As, this poll is still alive, P-51. Considered the best by most German and Japanese opponents.

Since I just posted an analysis of the P-47D here ...

http://www.ww2aircraft.net/forum/technical/performance-analysis-p-47-a-17937.html

... I have the data now to prepare a comparison of two late-war examples of the two fighters "competing" here.

If there's anyone left who has not yet voted, that might be of interest for him

Regards,

Henning (HoHun)

 

[cuccos19]

The P-38 Lightning was better aircraft than these two in many aspects. Far versatile could use in all kind of task nearly. P-38 was available from the 1st day of the USA's war or far before that. It had two engines what gave him a second chance to go home if one had shot. It's firepower was concentrated into "one point" nearly much easier to aim. Its 4x .50MG had 500rpg, like P-51(D for example, as the most famous and widespread) only had 4x 270rpg and 2x400rpg in same caliber. P-38 total was 2000rounds, P-51D was 1880rounds, and less firing time. Oh yes, and Lightning had an extra 20mm cannon with 150rounds.

Lightnings major problem were less roll rate until it got the hydraulic aileron boosters, difficult to recover from diving what had solved with the diving-flaps, insufficient cockpit heat(!), and the fact that USAAF used bad fuel to operate those Allison engines with the GE turbosuperchargers in the ETO (8th AF I think what based in the UK, GB or whatever). The engines simple went wrong or "blown-up" after 80-100hours of work. But there were no problem with P-38s in the MTO (North Africa where the conditions were much worse) and in the PTO or China-Burma-India theater. They serviced the plane there with right fuel simply.

An other choice instead off the P-47 would be the F4U Corsair. Simply superior in my oppinion, but it was for the Navy and Marines. Navy and Marines simply could not use the Thunderbolts, so the Army could not get the Corsairs, there were too few of them. P-47 and F4U used quite the same P&W R-2800 engine, but the Corsair's one had a big disadvantage. It had mechanical supercharger but Thunderbolt's had turbosupercharger which didn't required and pilot management.

 

[HoHun]

Hi Cuccos,

>The P-38 Lightning was better aircraft than these two in many aspects.

Hm, here is a thread with a comparison to the P-51:

http://www.ww2aircraft.net/forum/polls/p-38-lightning-vs-p-51-mustang-better-fighter-3867.html

Post #329 has a similar performance comparison as the one above.

Regards,

Henning (HoHun)

 

[aads]

The p-47 served for longer
It was faster
it was the first to down a 262
the top ace in the ETO flew one exclusively
It had better firepower and survivability
the p-51 came in as the luftwaffe was waining and pilots were in short supply , luftwaffe numbers were lower
could out dive anything else
the most produced allied fighter

anything i missed?

oh and the 56th who flew it exclusively had the best record in the ETO - 1000 + destroyed ????
ohh and the mustang was a failure untill it got an english engine

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[renrich]

Nothing like jumping in fearlessly!

 

[Glider]

anything i missed?


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Yep. the P47 lacked the range to do the job that needed to be done, when it needed to be done.

 

[aads]

P-47 n

By the way hello every one.

and the 47s were the best plane at the time before the p-51d came along , then in turn the p-47n beat it on range .

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[Glider]

P-47 n

By the way hello every one.

and the 47s were the best plane at the time before the p-51d came along , then in turn the p-47n beat it on range .

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I think you missed the When it needed to be done. The P47N was way too late

 

[aads]

Ok then, just say ithe n was too late - what of these other points are the mustang better at?

Any?

 

[Glider]

It doesn't matter. If you are too late into the fray, then you may as well not be there. As an example, many people believe that the TA152 was the best piston engine fighter of the war, but it doesn't really matter, as again it was too late.

The P47N and the P51H were both too late as the piston engine era was almost over. After all, the P47 was taken out of service if I remember correctly by 1949 whereas the P51 served in Korea. On that basis the P51 had the edge.

 

[aads]

It served in Korea as there were not as many N model p-47s , plain and simple , it was the preferred ground attack weapon , which was mainly what the 51 was used for in korea , but for comminality problems the 51 was used as there were several more in theatre at the time.

Range is the only place really it had the 47 beat the numbers speak for themselves. It cant speak dont lie as they say

 

[Coors9]

As long as it has a birdcage, I'll take either one.......Boy their pretty

 

[drgondog]

Ok then, just say ithe n was too late - what of these other points are the mustang better at?

Any?

How about climb, acceleration, manuever, take off roll, landing roll? The P-47N and P-51H came into the USAAF inventory at nearly the same time but the USAAF kept them stateside.

The 47 had twice as many combat sorties and a little over half the air to air record and far less in groaud awards of enarmy aircraft as the P-51. It had a much lower air to air ratio and in the 8th AF did not have a significant advantage in strafing losses.

Until the P-47D-27 and beyond, the Jug was playing Penetration and Withdrawal support up to the German/French border while the Mustangs were taking on the Luftwaffe over Berlin

As to Korea -

PRE-Korea the USAF did not have an unlimited budget and the choice was jet for air superiority (P-80 then F-86), jet for gound support (F-84), P-51 for strategic escort, P-82 for long range escort and all weather night fighter as the P-61s were being retired.

The USAF, had it had long range crystal ball, in 1946 relative to Korean War, would have been better served to get an air force version of the A1-D rather than the P-47 or P-38. They weren't stupid, the P-47N and P-38L were both more expensive, not perceived as good for strategic escort, and nowhere close to P-80 or F-84 or F-86 in air superiority role.

So 38 and 47 were cut.

 

[renrich]

There ain't no free lunch when it comes to airplanes. An extreme example is the F4F. One of it's shortcomings was lack of range(compared to the Zeke) Grumman solved that problem with the F4F7 which carried 685 gallons of fuel, 555 in a "wet wing". They only built 21 of them because the performance suffered so much among other problems. The P47 N suffered a little like the F4F7

 

[pinehilljoe]

I can't help thinking one reason (and perhaps dominating reason) the P-51 was chosen for post war service over the 47N was North American management was better at politics and lobbying than the Republic Management.