I HAVE A DIRECT CONNECTION 10-300 ULTIMATE BIPE. THE WING SPAN IS 62 IN. DOES ANYONE KNOW WHERE THE C/G WOULD BE FOR THIS PLANE. ALSO THERE WEB SITE [ DIRECT CONNECTION ] SAYS THIS PLANE WILL FLY WITH A 91 2/S TO A 120 F/S. HAS ANYONE INSTALLED A LARGER ENGINE AND IF SO WHAT SIZE. I AM CONSIDERING A MOKI 135 AND WAS WONDERING IF THIS IS TOO MUCH FOR THIS PLANE. THANK YOU.

I am pretty sure that the method to find a good starting CG for a bipe has been discussed here in the past. You should search for it and see if you can find it.

In short, find the mean aerodynamic cord of the wings and set the CG to be 25% of that to start. The MAC of a positive stagger bipe is the distance from the LE of the top wing to the TE of the bottom wing. Then you can adjust the CG via flight testing to the point that best suits your flying style.

Just for the heck of it, I believe that you will find a good starting C/G location at a point just forward of the rear most cabane mount. Every Ultimate and Ultimate Pitts I have seen works at this location for a starting point. You can start at the rear cabane and probably not get into any trouble.

As far as the mathmatical formula is concerned, I have found that about 28 to 30% of MAC works best for me in aerobatic bipes. Have fun!

Silversurfer

I had a Saito 150 in a Dave Patric 60.5" bipe and it wasn't overpowered . My friend has the Saito 150 in a Goldberg 58" bipe.
I think your Moki will work nice.

Phillco,

The Direct Connections kit came as a 56" wing span and could be built as 60". Are you sure it is a Direct Connection 10 Dash 300S ARC?

Fiberglass gear with a wood plate glued on that finishes off the bottom of the fuse? Rear of fuse at bottom shaped, not flat slab side?

If so the CG is 5-1/2" back from the leading edge of the top wing. With wings installed. As per page 23 step 1.64.

Throws are:

Ailerons- 1/2" up and down
Rudder- 3" each direction at farthest point
Elevator- 1" up and down measured at front tip of counterbalance.

Please be sure it is the Direct Connections kit and not an Ohio or some other kit. That's not the "standard" wing span as per the kit instructions (but hey, anythings possible). I'd feel bad if you used this CG on the wrong Ultimate and crashed.


Hope this helps,

Scott

I am using an OS BGX 3500 (2.15 ci) in a Lanier Ultimate Pitts. Wingspan is close to 61", weight is around 14 pounds.

I think your engine choice is a good one. There is nothing worse than an under powered bipe that wants to snap out of the sky due to a small engine.

Silversurfer

He has all the correct info.

Are you sure it isn't a ISC Tucker Pitts ?

Look at the picture of mine. See how the shape of the fuse is at the front and how the cowl is short.

The fuse is all sheeted.

Is that yours? Someones beem working the x-acto knife!

NOW I AM CONFUSED. I THOUGHT IT WAS DIRECT CONNECTION. I HAD ONE BEFORE AND IT LOOKS A LOT LIKE IT. THE COWL DOES NOT HAVE A RING INSIDE [ LIKE D/C ] THATS BOLTS TO THE FIREWALL. THIS HAS BLOCKS AND THE SCREWS ATTACH FROM THE OUTSIDE. IT DOES HAVE THE FILLER BLOCK THAT COVERS THE L/G AND THE FUSE IS SHEETED BUT THE D/C WAS ALSO THIS WAY. IT LOOKS LIKE THE PICTURE THE EDGE ATTACHED. IT ALSO HAS FLYING WIRES ON THE TAIL FEATHERS. I COULD NOT SEE THIS ON [ THE EDGE ] PICTURE.
THE PLANE WAS PROFESSIONALLY COVERED IN A TEAL COLOR AND LOOKS GREAT.
ITS ALL TOGETHER WITH NO TANK/ SERVOS OR ENGINE.IT WEIGHTS RIGHT AT 6.5 LBS.
I APPRECIATE ALL THE FEED BACK. THANKS PHILLCO

THANKS SCOTT FOR THE HELP.

The Edge,

Wow, nice job on the bipe. I'm not sure if I like your XKE or your bipe better!

Funny thing, My D.C. Ultimate has a short cowl too. And it doesn't have the ring to mount it with either. But it does hang down below the bottom of the fuse about 1/4" to let air escape.

I got this on a trade, so it's been around the block a few times.

It does have hard points for the flying wires on the tail. There is a built up plate that glues to the bottom wing to finish off the bottom of the fuse. But probably the coolest thing is how he made the rear of the fuselage contoured. It really looks nice.

I looked at my top wing mount and it looks like the rear cabane screws on at about 6" from the front tip of the wing.

Phillco,

Best of luck wished I could have been more help.

Scott

ANOTHER QUESTION ON THE OHIO RC ULTIMATE. WHAT SERVO [ OZ IN TQ ] WOULD YOU RECOMMEND FOR THIS PLANE?