Weight Difference

bdon661

bdon661

New member
Has anyone ever calculated the difference in weight between a set of 14-13 wings skinned in the correct skin thickness versus what they would weigh if they were skinned in the slightly thicker 14-19 skins?

My airplane is on a diet - over the next year, it will get an alternator instead of a generator, a light weight starter, and a light weight battery. I'm curious if the overall weight savings would make slightly thicker wing skins viable from the standpoint of weight. A local DER is willing to support approval provided the weight and CG change are reasonable. He's looking at drawings and other data right now so he can enumerate 'reasonable'.

Brad Donner
NC86916
 
Remember that the Cruisair has about double the number of ribs as the 14-19, so putting the thicker skin on would end up with a wing heavier than a 14-19. The "Hungry Horse" look of some of the Cruisairs, I think comes from the directional laying of the ply grain. There was a good article years ago about a fellow that rebuilt his wings and you could see every rib. Somehow he found out that the direction of the grain made most of the difference and he re-skinned his whole wings again. I believe it was in the earlier club magazine called THE BELLANCA PILOT. I think you can buy copies of the old club magazine from Bob at our present club. ____Grant. P.S., I think there might even have been discussion of the gluing being done within certain humidity limits.
 
Thanks Grant! I'm familiar with at least one article where a rebuilder re-skinned an entire wing because of the way it looked. My wings also have the "hungry horse" look, with a substantial amount of the ribs visible under the skin and my thought process has been to build up a spare set of wings with the thicker skins that avoid that appearance.

I agree completely about the potentially large weight difference. We're trying to calculate that now and I'm going to reach out to Dan C. after the holiday weekend and see if he has a better quality set of wing blueprints than what I have here. The initial computation of weight difference is 'easy' at first glance. Obtain the difference in skin weight per square foot and multiple this difference by the total surface area of the wing skins and you get a number. But......... that number is only part of the total. How you glue / nail / fill the skins changes based on the material used. Do thicker skins require more glue / nails / filler (I have no idea)? If yes, how much do the additional materials add to the total weight of the wings?

It's an interesting academic question that I'm going to have some fun with once the heat here reaches the "I don't need to go the airport" level. BTW, if you know of anyone with a spare set of 14-13 wings :)

Brad Donner
NC86916
 
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