ORIGINAL: Build-n-flyer-RCU
I never thought about it that way, but yes .1 cu in per lb for a conventional 4-stroke is a good rule of thumb for adequate flying power. But I would make this a minimum for a warbird that needs to go fast to fly "scale". Since the full-scale Seafury topped out at over 450 MPH I would say that your model counts as one of these!
A 6 pitch prop is fine for a 40-size warbird, especially with a 2-stroke engine. But I've found that as the models get bigger and the engine RPM for the larger engines is lower (especially with a 4-stroke) more pitch is needed to get adequate flight speed. An 8 pitch on a 4-stroke sounds about right for your plane, I think that you would find that with a 6 pitch prop the 'Fury will look like it is just cruising along even when at full throttle.
Walt
Obviously, some interpret scale flying differently than others. Altho a full scale Sea Fury may have been capable of 450 mph, I doubt that it was anywhere near sea level at the speed. Most '400 mph' planes (except for race planes) top out at closer to 300 mph, maybe 350 at sea level.
But the real point I want to make is: the models we are talking about here are typically 1/8 ~ 1/7 scale, so a scale speed would be those fractions multiplied by what the full scale flies at. In the case of a 400 full scale, a 1/8 scale would then be a 50 mph model.
My previous Top Flite Corsair used Master Airscrew 3 blade 12 x 6 props, and flew quite well and at scale speeds, while putting along at 2/3 throttle. I could even enter loops at the setting, throttling up as I entered it, and backing off on the down side.
I could make very slow passes at just above idle, with the gear and flaps up.
Scale flying is a subject of it's own, and subject to debate. Some think fast, VERY fast, while others think differently. I think what is really unfortunate is that some warbird events (such as Terre Haute, IN Warbird Day) judge best flight as the one in which a warbird has a higher power to weight ratio than all the others, is able to take off and fly straight up, and ideally even hover. In my opinion, "Best Flight" at a warbird event should go to the most realistic looking flight. Just my opinion.