ORIGINAL: Rcpilet
ORIGINAL: branded
ORIGINAL: Rcpilet
I think foam is always going to be heavier than built up.
Whats all that space between the ribs in a built up wing? Air
Whats air weigh? Nothing
Whats foam weigh? Solid foam wing?
Even using 1 pound density foam--compared to 8 pound balsa. I still think balsa built up is lighter than foam. There is very little of that balsa in a built up wing.
Thats my totally biased opinion because I prefer a built up wing over foam sheeted. IMO--sheeting foam wings is a pain in the butt. I can frame up a wing pretty quick.
Uh, air has weight to it just as any other fluid. What's in a built up wing is alot of stuff not found in a foam core wing: ribs, spars, shear webs, etc.
This brings the weight of the two types of wings very close to each other, particularly when speaking of larger sized airplanes.
I find foam core wings much quicker to build up but they do require some aquired experience, particularly when cutting out control surfaces, planning for retracts, etc......
I disagree about air having weight to it. Thats an argument over symantecs and pointless in this discussion.
I kow how to build a foam wing. Done a few dozen of them. I just don't like it.
You still have spars in some foam wings. You still have a leading edge piece of balsa on the wing. You still have a trailing edge piece on the wing AND another leading edge piece on the control surface. You still have caps on the root and tip. Just like a balsa plane.
A balsa wing isn't always sheeted on the whole wing--so there is weight savings over a foam wing. A balsa wing has a lot of air in it and air weighs less than foam--I don't care what planet you live on. Foam is heavier than air--thats the point.
Look how much more glue it takes to install a phenolic tube in a foam wing as opposed to a built up wing. On a foam wing, you really should be coating the entire socket with glue and making sure you get glue on every part of the tube when its in the socket.
In a built up wing, your only going to put glue where the phenolic touches the ribs. If your a good builder, you wipe off runs and keep the glue neat.
Glue weighs something. There's a lot more glue in a foam wing than a built up wing. I certainly think there is.
Okay, your turn ....
Maybe we should do an experiment? I'm fixin to build an 80" wing with about 980 sq.in this summer. It will be a traditional balsa wing. Maybe I should weigh it as I build and you should start that kit you've been eyeballing for the last 2yrs. You know, the one with the foam wings?
Well, perhaps you should inflate your wings with some helium, a
lighter than air fluid......Air, the volume of the cavities between ribs, is relevant to this discussion....The more ribs, and balsa structure, the less volume of air.....and the more weight introduced by structural members, for a given sized built up wing.
I only speak from 35 years of experience....I've built both kinds of wings. Foam core wings require less structure and are inherently stronger.
Yes, there are spars and structure in a foam wing but far less than that of a built up wing....which makes up for the additional volume of the foam....
Helium anyone?