Macchi C.202 structural question

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MDriskill
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Macchi C.202 structural question

Post by MDriskill » Fri Feb 02, 2024 11:43 am

A small mystery: these two photos have appeared in several books...with no comment on the obvious large diff between them. Note that the C.202's fuselage had 19 vertical frames, numbered in factory drawings from 0 (firewall) to 18 (tail cone attachment).

The lower shot has the three normal upper openings, for: gun bay (A, frames 0 to 4); cockpit (B, frames 4 to 7); and radio access cover (C, frames 12 and 13).

The upper shot has another large opening between frames 7 and 10, with frames 8 and 9 doubled! Is that a production change? 2-seat trainer? Or...?

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Re: Macchi C.202 structural question

Post by Editor » Fri Feb 02, 2024 7:54 pm

That's the location of the dorsal hump, the frames should have been doubled (strengthened) there (cg) to take the load of an aircraft flipped-over.

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Re: Macchi C.202 structural question

Post by MDriskill » Sat Feb 03, 2024 11:42 am

Thanks Vince!

To the best of my knowledge though, the lower drawing is the typical C.202 structure; and the usual method of attaching the separate turnover structure directly to the skinning and tops of the frames, worked well enough. Such a major change to the framing as in the upper drawing, seems like it must been for another large opening on top of the fuselage.

Again, what may be even odder than whatever this is...is that no one who has published the photo, has noticed and commented on it! šŸ˜

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Re: Macchi C.202 structural question

Post by Editor » Sat Feb 03, 2024 4:07 pm

The dorsal fairing was definitely fastened to the frames with thick beams added at 90o degrees to reinforce the frames from crumbling on impact - if you extend the drawing above you can see how the dorsal hump was attached to the frames. Interesting post, but I don't think the double frames were provisions for a dual-seater, the fuselage would have had to been lengthened, the plane would have looked something like a Bf109G-12 or the postwar G.55B or even a CR.42B, extending the fuselage by at least 8-12inches and moving things around to get the center of gravity correct, in fact the G-12 never quiet got it right and ironically it was considered a dangerous plane to fly, or at least that's what pilots said and the Germans only made a few from converted airframes - it was not successful. But no doubt a dedicated trainer obviously would have shortened the training syllabus at a time when pilots were needed most. Also there just never were enough C.202s around for the RA to concentrate on building a dedicated C.202 trainer, especially since there were plenty of trainers already available, even C.200s were being used as advanced trainers at that point. Just as a side note the C.200 also exhibited double frames in the front fuselage and also around the cockpit but not around the rear-fairing which suggests local strengthen of the frames at points that were needed. The C.200 could carry a fuel cell behind the cockpit but pilots didn't like it because it changed the balance of the aircraft but the C.202 had a (self-sealing) 80l fuel tank behind the cockpit as well as pneumatic equipment (a camera could be installed as you know) and compressed tanks in that area. From an engineering perspective the double frames suggest an after-thought, probably after testing revealed strengthening was needed and Castoldi and his team were no strangers to making simple ad hoc design changes on the fly e.g., shortened wing. If you find anything to the contrary I'd be interested to know, even if the double frames were somehow meant for a converted trainer that would be a new discovery.

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Re: Macchi C.202 structural question

Post by MDriskill » Mon Feb 05, 2024 11:49 am

Thanks again!

It's a head-scratcher for sure. I can't imagine that an opening so large, was for anything other than a second cockpit. But I agree with you - I also can't imagine how that could have worked! The structural, balance, and aerodynamic issues (would it not have blanked off the rudder?) seem huge.

Which may well explain why we've never seen anything beyond this single "skeleton," ha.

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