P-36 Hawk, Model 75, Mohawk, P-37, P-40 Warhawk, Tomahawk, and Kittyhawk, & P-42

[Arc3371]

Sorry, I meant the P-36 cowl

[jcf]

But then there's engine diameter. The Ash-82's diameter is 126 cm (49.6") compared with the Twin Wasp's 112 cm (44.15"). Yet when the sideviews are "in scale", the entire Shvetsov cowling would almost slip inside the opening for the R-1830.

Anyone have a idea of what has gone awry?

The Ash-82 installation of the LA-5, based on MiG work BTW, was extremely compact with a tight circular cowling.
Some consider it an even cleaner installation than the BMW 801 of the Fw 190.

The P-36 was from an earlier era and is not as closely cowled, the cowling is actually oval.

These Hawk 75 walk around photos show the difference in design.







http://www.aircraftwalkarounds.be/Images/CurtisHawk75Part1/index.html

http://www.aircraftwalkarounds.be/Images/CurtisHawk75AssemblyFirstF/index.html

http://www.aircraftwalkarounds.be/Images/CurtisHawk75Part3Engine/index.html
Jon

[jcf]

Thanks Jon. So ... despite the engine itself being more than 5 inches bigger in diameter, the cowled Ash-82 could still have been much smaller than the Twin Wasp top-to-bottom (to allow for the Hawk's oval)?

Yep, also bear in mind that five inches greater in diameter is only 2.5 inches larger radially, easily absorbed by good cowling design.

[redstar72]

I made a comparison cutaways of P-36 and La-5 - so you can see that La-5 cowling is actually much "closer" and more narrow. Actually, Lavochkin needed to make the cowling as narrow as possible - to fit the radial with streamlined LaGG fuselage.

[redstar72]

Yes, I forget: http://en.wikipedia.org/wiki/Pratt_&_Whitney_R-1830 says that R-1830 diameter was 48.03'' (122 cm).

[jcf]

P & W and Wright engine reference PDFs on the AEHS website:
http://www.enginehistory.org/reference.htm

Twin-Wasp Jr./R-1535 (the original Curtiss 75 prototype engine, 44.13 in diameter))
http://www.enginehistory.org/P&W/R-1535/Twin%20Wasp%20Jr.pdf

Twin-Wasp/R-1830 (48.00 to 48.19 in diameter depending on dash number)
http://www.enginehistory.org/P&W/R-1830/R-1830Index.pdf

C-W (R-1820 starts on page 5, @ 53.75 to 55.75 in diameter depending on model & dash number)
http://www.enginehistory.org/Wright/CWafter1930_2.pdf


Original Model 75 with R-1535

Jon

[Arc3371]

Something is amiss. The P-40E-1 was 9.68 m long. The La-5FN about 8.5 m (8.6 m, and 8.67 m are also listed). A Hawk 75A was 8.69 m long. All well and good.

But then there's engine diameter. The Ash-82's diameter is 126 cm (49.6") compared with the Twin Wasp's 112 cm (44.15"). Yet when the sideviews are "in scale", the entire Shvetsov cowling would almost slip inside the opening for the R-1830.

Anyone have a idea of what has gone awry?

Would you mind if I used the linedrawings for some profiles?

[redstar72]

Good work! Elongated tail is a right decision - the M-82/ASh-82 was notably heavier than R-1830.

[Arc3371]

Arc: based on redstar72's excellent sideview sections, this might a bit more accurate.

Thanks!

[Arc3371]

Going OT but... How difficult would it be to mount a Allison V-1710 on the MS.406?

[redstar72]

How difficult would it be to mount a Allison V-1710 on the MS.406?

I think it would be not so difficult. The Morane has Hispano-Suiza HS-12Y engine; the same engine was license-built in the USSR as the M-100, and its derivatives were all the family of Klimov engines - M-103, famous M-105/VK-105, and VK-107. So, if it's possible to put the Allison into Yak-3 instead of the VK-105, why not to put it into Morane instead of HS-12Y?.. But the question is: how could it look? Maybe very similar to original HS-12Y cowling (the modern-built Allison-powered Yaks have cowlings very close to originals); maybe something completely different...

[Arc3371]

Thanks, wonder if the P-51A nose would fit...

[Weaver]

The Ms.406's nose was notably flat-topped, morso than even the Spitfire.

Great work on the ASh-82 version folks 

[Arc3371]

Thanks again for the insights which brings us back to the P-36, how about a P-36 with a D.520 nose (and engine)?

[Arc3371]

Ah, could you post a bigger version?