haroldpo6

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Hi all, I just maidened a profile bipe that I scratch built from some old sig funfly plans with the goal of putting it on a diet, which I did.
The plane wanted to dive real bad and I had to put a lot of up elev in the trim, other than that it flew great. After landing I looked at the elev trim and it had quit a bit of trim. After checking the incidence on the top and bottom wing I found + incidence on both of about 2 degrees or more(don't have incidence meter) using small level and ruler. Wouldn't this clause the plane to climb instead of dive? The plans call for 0-0-0 on wings, engine. Balance was a tad nose heavy. What ya'll think?

Villa

Hi haroldpo6
That is one fine looking Biplane. About 8 years ago I built the same Sig Profile Biplane from their kit. A great plane to fly. Without an incidence meter your measurements may be off a little. It being nose heavy would cause what you have seen. I would correct that first, doing it in small steps. Do a knife edge to judge the CG. Is your front landing gear made from the soft aluminum available at places like Lowe's Home Builders? Here is my design of a profile SPAD Biplane made from Coroplast. http://www.rcuniverse.com/forum/m_8007330/tm.htm . Please keep us posted on what you do.

haroldpo6

My Feedback: (10)

The landing gear I got from Sig for there kits. I have set both wings and engine to -0- but haven't flown it again yet.

Total WT. 4lbs 9oz ready to fly.
OS 55ax @ 14.25oz
12x6 APC going to try a 12.25x3.75W APC and a 13x4 APC when the engine gets a little more time and the plane is dailed in.

Villa

Hi haroldpo6
With that engine you will have a screamer. On my Sig Biplane I broke the fuselage 2-3 times. The first time was from a wing stall at landing. I was shocked that the fuselage had broken. I ended up fiber-glassing the whole length of fuselage. I only had an OS46FX on mine. Now that I think of it, my Sig Biplane frequently landed hard because eventually the Sig provided profile landing gear broke from being bent once too often. I later use a fiberglass profile gear sold by Tower Hobbies. My new Coroplast Biplane is about as light as yours and lands very light. I have everything at 0,0,0,0. I had to cut back on the prop when I noticed that the plane was yawing right/left a little at high speed. As you know, a biplane has a lot of wing drag. My guess is I was exceeding some reasonable speed. They are not built for speed. I changed the prop (more pull, less speed) and it performs much better. I built mine with symmetrical wings so it is exceptionally acrobatic. Let me know how yours does after your changes.

haroldpo6

My Feedback: (10)

My fuselage is made of 1/2 balsa sandwiched between liteply with lightning holes for wt savings, seems very strong and lite.
The OS 55 does not seem to have the power I thought it would, not a high rpm engine, but runs very nice. That is why I will change to a lower pitch prop for less speed and more thrust. Landings are very slow and easy. No tip stall at all. I have read that it would fall out of the sky if you slowed down to much on landings, this one will float right on by if the idle is not set low. If the wind will quit blowing a gail i'll try it again friday.

Villa

Hi haroldpo6
Looks like you have it under control. You should be able to hang it on the prop. I like to do an up elevator 180, down elevator 180, up elevator 180, etc, kind of like climbing a ladder, till the plane gets up to high.

haroldpo6

My Feedback: (10)

Tried again this morning early and it flies great now, tried the 12.25x3.75APC and I ilke it better. Now I need 13x4APC and try that.