I had an OS120FSIII pumped w/ tank on the CG. Flew well, VERY VERY slow, verticalled fine, but not good enough for 3D. I took my Saito 180 out of my Sig Extra and mounted it on the Ultimate. Turned out that the 180 actually weighs LESS than the 120 and produced 2.8hp vs 2.3hp. Now my uplines are not only radicall, but I hover this bipe w/ extreme confidence "AND" slow flight has actually improved! Don't forget to double bevell tail surfaces for max throw and mount all gear aft.

I flew my kit version for a few years on a Super Tigre S90 with Zinger 14x6 prop. Not quite unlimitted verticle, but good climb rate for 400-500 feet. I saw one fly with a modified YS120, bored out to a 140 the guy said. It didn't really fly, it more or less was drug around by that monster! He'd go verticle forever, and I watched his throttle stick stay at about 1/2 point the whole time. Quiet as you can imagine too, since he was truely only running between 5k and 6k rpm. It was swinging an APC 16x8 prop, don't know what kind of fuel he ran.

My vote would go to a YS120. I'd planned on switching mine out, but decided to trade the plane for something else.

My first CG Ultimate was given to me with at 60 2 stroke. I had a YS 120 with a pre drilled aluminum beam mount that I wanted to put in it. Needed to move the FW back 1/2" too. Wasn't hard to do at all. On my second one, a kit, I already knew what I needed to do and it was even easier to do the second time around.

Did you mount the elevator servos at the tail? If you add 2 servos at the tail, 1.5 oz each, that's 3 oz at the tail, more than enough to offset 6 oz of extra weight at the nose. If you use high performance servos that weighs 2 oz each, you will offset 8 oz of engine weight, which is the difference between Saito 100 (20.8 oz) & Saito 120S (28.86 oz).

I guess I am the only one happy with my CGM Ultimate/Os 91 Surpass 2. I use a 14X6 prop. It balances right on the money with this motor with no extra weight and will fly like a pattern ship. I cannot do 3D but can do any standard pattern acrobatics. I bet the power to weight ratio os better than with the full scale Ultimate. If I had to do it all over I would go with the Saito 100 and 30% nitro fuel. I think you will very be happy with the Saito 120 if you can get creative enough with radio placement etc to keep from adding weight.

Mine is set up with the Saito 180. I have my servos mounted next to the former under the rear wing bolt plate. With this setup and the satio 180, the plane bal. just right. The cowling may be a little heavy to. The all up weight is around 9.5-10 lbs. Don't worry about the weight as they fly very good. I love the way it flys and would not change a thing. Go with the 120...you will like it.

I have the CGM Ultimate Arf sitting on my bench in its final stages with a brand new Saito 100. I checked with CGM (when I purchased the ARF) and their tech support told me the Saito 100 would be an awesome engine for this ARF. I also put out a thread on this subject about six months ago and a flyer in Indiana had the exact same setup and said the Saito 100 because of its light weight and power made his bipe an ultimate preformer with unlimited vertical. I've read a lot of threads on this model and the general consensus is to keep it as light as possible - it will fly better.

I'll throw up a post in the spring when I fly my Ultimate and tell you if the CGM tech support was right.

SearchMan

I am hoping to get the kit and make it a winter project but I want to make a good engine selection prior to building it. I was under the impression that an all up weight of 8-9 lbs is achievable. If so a 120 4 stroke should give more power for 3D.. Am I correct in this assumption?? I do want to do 3D with the plane and don't really want to spend 400 for a motor. I was hoping to either look at a 90-120 2 stroke or 120 4 stroke. Let me know what you think?
Jeff

OS 1.08 turning APC 16x6 @ 10500 would be perfect. $250. I think only the Bisson Pitts muffler ($30) will fit in its streamlined cowl.

Or actually, the Super Tiger G90 can turn a rather large prop for its size, like the 15x6, at over 10,000. $150. Likewise, BCM $30.

I myself would get the YS 1.10 when it comes out, which has the best power-to-weight-throttle-response-CG-constancy for 3D. I think it will cost $300. I have a Goldberg Extra, which I think I will put the YS 110 in when it does come out.

Go with an RCS140 gasser!!! Put the elevator and rudder servos in the tail and fire up the little gasser swingin' an 18x8!!!! Outstanding performance...VERY doscile or extremely 3d capable. Couldn't ask for anything more. Especially the way that the bigger 2-4 strokes guzzle nitro. :thumbup: