i was recently given a old biplane project and i dont have any idea what it is looking for any help. top wing is 71 inches bottom wing is 64 inches fuse is 48 inches from firewall to tip of fuse tail section. plane is missing the vertical and horizontal stabs and control surfaces. one thing that might help to figure out what it is is that the fuse and wings are both foam core. any info would be great and if someone has the plans the tail section info would also be nice, and cg and motor size info would also be helpful.

There have been very few kits on the market with foam fuses and even fewer were bipes. In fact, I have yet to hear of a foam fuse bipe kit. Most likely, you have someone's scratch built project. The wings look a little close together, but that may just be the angle of the picture. Build a set of tail feathers for it and stick it in the air!

John

could very well be a scrath kit not sure the wings are 8 inches apart from the top of the bottom wing and bottom of the top wing. that is what will most likly happen is just dream up my own tail and make it fly thak you for your response

The general rule of thumb on bipe design is that the upper and lower wings should separated by the chord of the smaller wing. But, that is just a general rule. I forget what the exact rule of thumb for tail surface area is supposed to be, but I think it's 33% of 75% of the total combined area of both wings. Example. If the total area of both wings combined is 1000 sq/in's, then the tail should be 33% of 750 sq/in's = 250 sq/in's. Chuck Cunningham went over this many times in his RCM column so I'm sure there is someone around here who can confirm or deny that formula. CG is determined as by plotting out the stagger of the two wings, compare area between the two and measuring back aprox. 25-30% of the average chord. For the engine. You have the engine mount so a quick measure meant of the beam width should give you an idea on what size to use. Then again, the mount may be marked as 40-45

With the amount of measuring and figuring you have in front of you, there's a very good chance you will have something to be very proud of once it's in the air.

Good luck,
John

I got this off the net, but it sounds right. Stab area is 20-22 of wing area. Aspect ratio of 3:1. Elevator is 20% of stab. Fin is 1/3 of the stab area. Rudder is 1/3 to 1/2 of fin area. I think that is light. I also saw that you can use 7% of wing area with 35% of that for the rudder.

Use this with a grain of salt. it is just info I got from the net. You can always go slightly bigger. I would, especially with a bipe. With the close coupled wings I would definately enlarge the stab and elevator some. Good luck with this project.

Mark Shuman

thanks again guys for the input should be a nice flyer i would think by the looks of it. but time will tell