Big for Crimson Skies, I loved that game on computer growing up.
I have seen (somewhere) a video of a foamboard Devastator flying, it flew pretty well considering.
The Firebrand is just a flying wing, no reason that shouldn't work.
Likewise, the Kestrel is essentially a P-38, and we know those fly well.
The Bloodhawk is a canard design, those can work, but they are problematic to design. I would suspect a model would need the size of the canards increased for stability.
The Avenger is a pretty straight forward twin-engine design, again I see no reason why that wouldn't work as long as it was balanced properly.
Even the pusher prop design Peacemaker should work.
I guess what I'm getting at is that a lot of the planes in Crimson Skies should work as long as they are balanced properly and have enough lift surfaces and control surfaces.
There are a couple designs that would be far more difficult I think.
I think the J2 Fury would be quite the handful given the wing placement and tail surface. The wings are pushed way back and it's not a canard design. It also lacks any vertical control surface, which means it would need to fly more like a wing.
He's right there are a number of them in the challenge... many are mine... I suppose I should finish them up huh?
I have been actively distracting myself with other builds... I have a couple ready to test. (have to setup the motor properly.)