# biggest speed spread over development



## billswagger (Nov 2, 2010)

This topic came up in another thread so i thought i would expand on it. 

The 109 was a sleek design from the beginning and didn't need much modification to get a bigger engine in it, however, there were parts better developed for those new high speeds and at higher altitudes. 

Presumably the first 109s started out at about 280mph, and later models topped out at about 450mph. 
The 109H-1 came up in another thread with a marked top speed up to 466mph. 
This gives spread of performance over speed, in the range of 186mph. 

I doubt you'd find other aircraft that come close to those figures seeing as most of them were faster out of the gate. The war was on, and benchmarks were set when developing an aircraft. In most respects if an aircraft wasn't up to par it never saw production anyway. 

i've thought of a similar comparison of the P-35 into the P-47:
The P-35 started with a speed just over 300mph. 
The P-43 achieved a top speed of 356mph
The early P-47s exceeded 400mph, while Bs and Cs managed over 420mph. 
The P-47D managed to see gains over 430mph, and topping out above 440mph. 
The introduction of the M engine enabled many aircraft in service to exceed those speeds. The actual M prototype tested at 488mph. 
I think they sought to lower the drag profile with the J which achieved 507mph, but was later out shined by the P-72 which achieved 480 with out a turbocharger. Projections placed its top speed closer to 550mph. 
A little incite reveals the R-4360 was also installed on a half dozen P-47s at a time when R-2800 was topping out around 3200hp. 

Anyway, you take 300 from 550 and that gives about a 250 mph spread.
If you dont include the prototypes, then it ends up being closer to 200 mph. 

the spread you gave the 109 was only 186mph and i dont even know that the 109H flew beyond prototypes. 

I don't know if its a fair comparison, but you could also take the P-36 and measure its development into the P-40, in which the P-51 was born out of. I think you'd see similar speed spreads from those examples. 
P-36 early prototypes flew at 281mph. 
The fastest P-40s saw about 380mph. 
while the development of the P-51 exceeded 400mph using the same power plant. 
The P-51H saw speeds of 490mph. 
Thats a speed spread of 209mph between the three war planes. Probably not as remarkable as the spreads achieved by Messerschmidt or Seversky aircraft, but none the less, the efforts of Curtiss also contributed a lot to the late Mustang. 

There is also more that goes into performance than just speed. Many aircraft saw increases in climb and loading to allow for other functions during the war. You would also notice that most of the speed gains correlate with an altitude increase. 

I also have to question the instrumentation during the mid 1940s, particularly where the top speeds are above 450mph, and at higher altitudes. Its likely the measurements are a good 10-20mph uber, but if we are just looking at spreads, they probably all had the same level of error. 





Can you think of other aircraft companies that were able to make similar strides, particularly those developments that saw many similarities?

Bill


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## zoomar (Nov 4, 2010)

billswagger said:


> This topic came up in another thread so i thought i would expand on it.
> 
> I don't know if its a fair comparison, but you could also take the P-36 and measure its development into the P-40, in which the P-51 was born out of. I think you'd see similar speed spreads from those examples.
> P-36 early prototypes flew at 281mph.
> ...




You had me until the P-36-P40-P-51 thing. I think this has been discussed before but Curtiss's designs had no direct relationship to North American's Mustang. Actually, I just don't see any possible progression (even over multiple types)that comes close to matching the Bf-109, with the possible exception of the Seversky/Republic continuum. It think it's just too much of a stretch to consider the Hurricane/Typhoon/Tempest/Fury as a progession of one basic design concept. Anyway you look at it, the Luftwaffe was extremely fortunate it selected the Bf-109 in 1937 rather than the He-112. That's surely the best production decision Nazi Germany ever made.


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## Shortround6 (Nov 4, 2010)

Something I have aways wondered about when the topic of the P-51 being derived from work that Curtiss did on the P-40/P-46.

Why didn't Curtiss ever use this "Knowledge" in it's several attemtps to redesign the P-40s cooling system/ radiator?

Why didn't Curtiss use this "Knowledge" on any of the liquid cooled P-53/P-60 designs?


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## Colin1 (Nov 4, 2010)

Shortround6 said:


> Something I have aways wondered about when the topic of the P-51 being derived from work that Curtiss did on the P-40/P-46.
> 
> Why didn't Curtiss ever use this "Knowledge" in it's several attemtps to redesign the P-40s cooling system/ radiator?
> 
> Why didn't Curtiss use this "Knowledge" on any of the liquid cooled P-53/P-60 designs?


Curtiss were still turning out Hawks in 1944
They had their eye on Wall St, milking the P-40 cow was their priority

The XP-40Q was just barely a Curtiss venture; it was more accurately a small team of dedicated Curtiss engineers who gave up a bit of their free time to try and get it saleable.


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## tail end charlie (Nov 4, 2010)

zoomar said:


> You had me until the P-36-P40-P-51 thing. I think this has been discussed before but Curtiss's designs had no direct relationship to North American's Mustang. Actually, I just don't see any possible progression (even over multiple types)that comes close to matching the Bf-109, with the possible exception of the Seversky/Republic continuum. It think it's just too much of a stretch to consider the Hurricane/Typhoon/Tempest/Fury as a progession of one basic design concept. Anyway you look at it, the Luftwaffe was extremely fortunate it selected the Bf-109 in 1937 rather than the He-112. That's surely the best production decision Nazi Germany ever made.



The hurricane typhoon tempest sea fury were a progression in that basically one man was involved, making progress sometimes meant a step backward for Camm. I am sure given a free hand Willy Mesersschmidt would have designed a much better plane to be in service in 1944/45. The sea fury was developed from the tempest which was developed from the typhoon which was supposed to replace the Hurricane in about 1941 it didnt really surpass the spitfire until 1944/45. the continual evolution of the 109 (like the spitfire) kept it in the game if not always ahead of it.


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## Shortround6 (Nov 4, 2010)

Colin1 said:


> Curtiss were still turning out Hawks in 1944
> They had their eye on Wall St, milking the P-40 cow was their priority
> 
> The XP-40Q was just barely a Curtiss venture; it was more accurately a small team of dedicated Curtiss engineers who gave up a bit of their free time to try and get it saleable.



Doesn't answer the question about if Curtiss knew about/originated the radiator duct on the P-51 design why didn't they use it instead of that bury the radiators in the wing thing they did on the on the Q does it?

And I think that was the second or possibly third try at the radiators on the "Q" .


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## Colin1 (Nov 4, 2010)

Shortround6 said:


> Doesn't answer the question about if Curtiss knew about/originated the radiator duct on the P-51 design why didn't they use it instead of that bury the radiators in the thing they did on the Pn the Q does it?
> 
> And I think that was the second or possibly third try at the radiators on the "Q" .


I think it does answer it
if Curtiss's board are living off the fat of Wall St share prices and the orders are still coming in for the P-40, why bother with the hassle and expense of

a. hiring engineers, who will need paying, to go through the expensive design phase of a new fighter
b. tooling and jigging for the new fighter if and when their team come up with something

If Curtiss cared, NAA wouldn't have gotten a sniff of their cooling duct research material.


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## Shortround6 (Nov 4, 2010)

Colin1 said:


> I think it does answer it
> if Curtiss's board are living off the fat of Wall St share prices and the orders are still coming in for the P-40, why bother with the hassle and expense of
> 
> a. hiring engineers, who will need paying, to go through the expensive design phase of a new fighter
> ...



Curtiss had engineers, who were being paid, who came up with the P-46, the P-53, the P-55, and five variations of the P-60, the P-62 and the P-71. Navy fighter projects include the XF-14 and XF-15. Navy attack planes include the XBTC-1 and the XBTC-2 and there was the navy float plane Seahawk and of course the SBC2 Helldiver. I don't think Curtiss management was sitting back fat, dumb and happy expecting the P-40 to go on forever. 

having a few guys rework the radiator and duct on the P-40 doesn't seem like that big a deal consider that they did it several times.

http://img340.imageshack.us/img340/5160/xp4011.jpg

http://www.palba.cz/forumfoto/albums/userpics/11965/normal_xp40q1.jpg

The first P-60 used at least part of a P-40 fuselage with a new wing but a P-51 style radiator seems to be absent.

http://www.airwar.ru/image/idop/fww2/xp60/xp60-2.jpg

and it still seems to be missing on the XP-60A

http://www.aviastar.org/pictures/usa/curtiss_p-60_1.jpg

Strange that they would sell this knowledge to NA and then go on to build so many different radiator set ups themselves that show no sign of using that knowledge. If they could have gotten even another 10-15MPH from a different radiator design don't you think they would have done it?
After all, they could keep the same wing, same tail, same basic fuselage structure, same landing gear, just change the cowl and outer skin of the lower fuselage. keep the majority of the tooling the same and get more performance without resorting to the stunts/tricks that they used on the "N" model.


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## Shortround6 (Nov 4, 2010)

duplicate post.


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