Hawk 75 Design Study

I

Ivan

Charter Member
As folks may already know, I recently finished up and released a fairly long running project: the Hawk 81 or P-40C. When choosing to modify my old P-40E into a C model, there was always the consideration that there might be a quick follow-on project to convert the Hawk 81 into its ancestor the P-36 or Hawk 75. The direct conversion from P-40E would not work well because too much of the aircraft would need to change. There are major differences in shape between the P-40E and the P-36 besides the engine.

In a quick check on length and reference points, I found that the distance between the wing leading edge projected to the aircraft centerline at +3.12 feet Forward to the trailing edge of the Rudder was a perfect match. (Difference is around 0.005 feet)

I considered that to be a pretty good sign that the project was worth doing. It would be MUCH simpler than the conversion from P-40E to P-40C. When I drew up a few template parts, I found that things just didn't look right.

Attached is an image showing some fairly great differences. Note that the P-40E was done with a drawing that claimed to have factory dimensions. The P-40C lined up pretty well with the E model.

I wonder what happened here? Hate it whennat happens!
- Ivan.
 
After a bit more research, it appears that although the P-36 and (Long Nose) early P-40 appear the same superficially, there isn't very much shared between the two aircraft structurally. There apparently was quite a lot shared between the P-36 and the P-40 prototype but that did not continue with production aircraft. The hump backed fuselage LOOKS the same between the P-36 and early P-40 and that feature fooled me.

The next decision is whether the P-36 is worth building if it is not going to be a quick and easy project. Just about everything needs to be changed a little bit though that is still a whole lot easier than an entirely new project. From what I can tell, there has never been a really good P-36 / Hawk 75 built for CFS. One other consideration is that all this is based on my very old P-40E and that project was done with a center of gravity that is around two feet too far back. To change that means that all the texturing gets thrown off to a much greater extent than just small shape changes.

- Ivan.
 
I'm a bit surprised as I was under the impression that the P-40 was basically a P-36 with an Allison in-line engine, which permitted the swift transition from one to the other on the production lines as the tools and "jigs" were only modified to accommodate the new engine cowling.

Maybe "artistic license" has something to do with such marked differences in the two profiles? The tail section is very puzzling as I can't figure out a good reason to modify it so drastically.

Anyway, the P-36 would certainly be a good addition to North-African and early Pacific theaters scenarios, that's certain!:jump:
 
agreed, 'twould be an interesting project.

ah, go for it.
what else you got to do?

____:running:____
 
Hello Hubbabubba,

Your impression is pretty much what conventional wisdom says. There are still examples of the Hawk 75 and Hawk 81 around. When I compare the photographs, I believe that the shapes are just a touch different. The aft fuselage is a bit deeper in the Hawk 75. I don't believe it is artistic license in the drawings because this Paul Matt drawing I am using as a reference actually has stations marked which were courtesy of Curtiss-Wright.

I believe that if I were to build this beast, I would probably leave the CoG where it is now. I don't have a great deal of interest in this plane but I believe it would fit in the Army Air Corps 1930's inventory. My prefered paint scheme would be silver / light gray with pre-war insignia.


Hello Smilo,

I guess you are right.... I need another task to avoid boredom....

The others on my build list don't REALLY want to get their turn.
As concepts they can remain perfect.
As soon as construction starts, they become less perfect.

- Ivan.
 
You must log in or register to reply here.
Back
Top