Ultimate bipe balance
 

I picked up a Dave Patrick Ultimate bipe at a swap meet. Anyone out there have one that can tell me where the CG is suppoes to be? I just know from experience that I don't want to try and maiden a tail heavy airplane. From what I have read it flys fairly well. If anyone is interested in how it flys I will let you know once I get it in the air.

Thanks in advance for your help.

Randy

RE: Ultimate bipe balance
 

Got your answer for you: "The balance range for the Ultimate is 1 1/2" to 1/2" from the leading edge (front) of the read cabane - without fuel" That is published right out of the book. I built mine with an OS 1.60 and Tru-Turn Ultimate spinner and started the CG right at the 1/2" measurement point for starters. I found it to be a bit nose heavy and couldn't get the plane to float in during landings but had to trim with up elev. to maintain a flat attitude. Moving the CG back to the LE of the aft cabane has helped with all aspects of flying my plane, including those landings that cushion themselved in ground effect.

RE: Ultimate bipe balance
 

AWCflyer

Thanks for the help. To make sure I understand you started with the cg at 1/2 inch in front of the back cabane and moved it back another 1/2 inch to get it right? I've got a Saito 180 to put in it that probably doesn't pull as hard as the OS, but it should get me around. I was mounting servos in it when I stopped to check and see if there was a response to my question. Thanks again.

Randy

RE: Ultimate bipe balance
 

I can confirm that the DP Ultimate flies best with a rearward CG. Mine ended up right about at the front of the rear cabane to get it to fly like I like. The Ultimate flies great when balanced completely neutral (no trim change from upright to inverted), and will slow down to a crawl on landing with that CG. Awesome airplane, you'll love flying it.

RE: Ultimate bipe balance
 

Thanks for the help, I'll balance it where you guys suggest. Looks like someone hit something with the top wing and pulled the cabanes out so I had to replace the lite ply cabane mounts in the fuselage. I know on some bipes there is a small amount of negative incidence on the top wing but this one looks like it is going to turn out neutral. Can either of you tell me whether this is right or whether there is supposed to be some negative incidence and if so how much?

Randy

RE: Ultimate bipe balance
 

I'll have to check on that tomorrow when I get it all together at the field. When I built mine way back when, I didn't bother to check the wings during the build-up but only the horizontal stabs. I've recovered the wings 2 months ago as well as added CF gear to lighten the load and get a bit more clearance for the prop. She is a great flyer after almost 4 seasons.
:D