I recently got a World Models Ultimate 30 from an auction. It came with a Magnum .52 4 stroke. I was looking for additional info on these bipes and came across your posts. I was hoping you could give me some additional info. Here it goes:

1. What prop and tach reading would you recommend for this engine?

2. What is the balance point for this bipe.

3. Do you know where I can get a cowl for this bipe?

Thanks in advance

Here are some pics below:

How strange, I just took mine off the garage ceiling yesterday, charged it up, and flew it 3 times after work. Still just the same, reliable old Ultimate, still got some nice comments. Then I look in RCU, see my name, and this plane!

I use a 12X6 APC, after trying 11X6 & 11X7 & 12X7. Works great for me, but I have no clue what the tach would read.

The balance point is listed in my instructions as 81 mm behind the center of the leading edge of the top wing, but mine's balanced a little aft of that.

The cowl is ABS plastic, and nothing to write home about. I don't know if an aftermarket cowl is available, but you might contact World Models.

Is your top wing the type with the wire stay that slides in from the front, through holes in the upright? If so, you'll need reinforcement in the upright. I cut away the middle of the upright and epoxied in some aluminum tubing. Early on, the holes in the ply pulled through, for me.

Make sure your top wing is about 0.5 to 1.0 degrees Negative, with respect to the bottom wing. My bottom wing and horizontal stab have the same zero incidence, and my top wing is negative about .8. If you stall, the top wing stalls last. If you have the top wing with positive incidence, the plane wants to leap off the ground too soon, stall & snap.

I have over 300 flights on mine now, the covering is coming off in places, still flies nice.

Good luck,
Dave Olson

Thanks Dave for all your help!!!