Greetings all, I just wanted to run a couple #'s Past you guys and see what you think.

On a 15 size warbird, does 20 oz/sq foot sound excessive?

The P-39 is nearing completion, and I am a little worried about the weight. what do y'all think?


Thanks
Randy (Digger) Birt

PS. to make sure I did the calc right. She is 300 sq inches and looks to be about 42 oz when ready to fly.

Yep, thats 20.16 oz/sq ft.
Jollidude said his Simple Corsair flew great with a OS .15FP at 26 ozs but was heavy. His would have been around 19 oz/sq ft.

I have a Tequila Sunrise ARF (still in the box) that has 288 sq inches and it says the flying weight is 3.25 lbs on the box. That's 25.99 oz/sq ft.
I have a Norvel .25 to go on it, that should save some on the weight.
They say it is fast and the landing speed is something else.[X(]

I wouldnt be worried at all

AJC

Digger,

I have built alot of the .15 sized airplanes. Most were cut out by hand. One I remember in particular had 210 square inches and weighed about 2.25 pounds. That's what...about 25 oz/sq ft. No gear, just skid plates on the bottom. I'm not the best flyer around so when I say it wasn't too hard to land, that's probably like saying "It'll be no problem for you!" I'm not sure what the landing speed was, but it would only skid about 15'. I probably could have done better than that, but I never had the chance with that one. The fifth and last flight I put a 7x6 prop on it. After running an 8x4 prop and doing alot of rough flying I should have cut the control surface movement down a little. It reached well over 100mph when it started doing tricks and I was yelling "I LOST IT!!!"
Since your building a scale airplane, 42oz isn't that bad. A .15 LA will put out about 2.65 lbs static thrust. (assuming an 8x4 prop) That means your running about a 1 to 1 ratio. Combine that and the wing loading and it should fly pretty scale-like.

Thanks guys,
My concerns have now been put to rest. I knew you guys would help me out!

I'll let you know how it goes!

Randy (Digger) Birt

Digger,

I don't know, mine looks like it will weigh in somewhere around 30 - 32 ozs. You better beef up those spars a little more so that wing will handle all that lead your going to be flying around. LOL.

You go jump in a lake Louis!!!!

Yours is too lite! I think it will dry up and blow away!!!!!!!

Besides, what the heck is that dopey red star anyway? LOL!

Randy (Digger) Birt

Lou, is closer to the Big Muddy.