Hey guys,

I have a large profile plane that I really enjoyed building. I'd like to build a large profile bipe, 120-150 size, using the same profile techniques I used with the mono wing profile.

I'd like some suggestions on doing this.

Do I start with an existing plan then just build the profile fueslage? I want an easy flying aerobatic plane.

Is there an article or thread on converting a mono wing to a bip? Or bipe parameters?

Any ideas and suggestions will be welcome,

Thanks,
Flyinblind

HI FLYINBLIND! The individual wings of a bipe only have to be half as strong as those on a monoplane, by the time you are done cantilevering the 2 wings together, there won't be much unsupported span. The thickness of the individual airfoils needs to be somewhat thinner than a single wing fun fly. A bipe doesn't make full use of the lift provided by the individual wings because there is aerodynamic interference between the wings, the more distance there is between the 2 wings, the less interference, BUT I'm sure that there are practical limits to how far apart to set them. The thrust line should be centered between the 2 wings. I have built the GOLDBERG bipe in various sizes down to a 12 oz, .061 powered and they have all been lots of fun. No matter how lightly I tried building them, I have never had a structural failure, which leads me to believe that it's difficult to build one that's too light. If you are building a large profile, try to get a look at how the MORRIS HOBBIES 1.20 size job is put together, there is a build up thread in the profile forum. It would be pretty hard to improve on their design!

Thanks for the info!

Would you mind forwarding that thread to me. I've searched around and can't find it.

Appreciate you help!
FlinBlind

The rule of thumb I've seen in the past is that you want to have a minimum of one chord of separation. At 1 1/2 chord's separation they have so little blanking effect on each other that you can ignore it.

Full sized aircraft have flown with separations quite a bit less than one chord but there are drag problems associated with that method. I would consider going down to 0.8 chord separation but no less. And only if you NEED to. One chord is safe.

You'll want to reduce the chord down to about 1/2 or 0.6 of what it is. The biplane configuration concentrates the area without requireing a large chord so you can reduce the chord and the separation without reducing the wing area.