Has anyone flown this plane with an OS 70 four stroke? Also, has anyone mounted the engine right side up or sideways instead of upside down?

It will fly on a 70, however the plane will not have the power to do some of the 3D stuff. It will power similar to a low wing sport plane, not a 3D plane.

The plane was designed around the OS 91 four stroke. Many are flying the plane on Satio 100's and a few have stepped up and put YS 120's.

I flew mine off a OS 91 two stroke with a Jett muffler and it has plenty of power. If I were to do another UCD, I would power it with the new OS 91 FSH-C. The new black heli version with the Hyper Head and the Jett muffler.

If you have a 70, use it. It will fly the plane. Once you get comfortable with the plane, go to a bigger motor and really see what the plane will do.

If it's a money issue, I went with a Magnum xls .91 two stroke ($150). Plenty of power for 3D.

The engine mount will install as easily upside right as upside down.

My engine is mounted right side up without a cowl. You can fit the cowl over an upright engine if you want.

Leonard

PS I wonder if anybody wants to buy a never used UCD cowl?

I'm using a YS .91 that is well broken in, and inverted. It's a good engine for inverted flight so that is not an issue. As for power. It will hover well and it has enough power to pull out of a hover - barely! I'm running it with an APC 16 X 4 wide blade prop on 15% Cool Power and it weighs a tad over 7.3 lbs. More nitro would help, as YS engines really like nitro or I could go to a bigger engine, but I've already got 3.24 oz. of lead in the tail to offset the YS. I put the fuel tank right on the CG, which is the one specified in the book.

I just purchased one myself.

I am in the process of bolting on a OS 120 FS. The weight is still at 7 lbs. empty and minus pushrods. It's also a bit tail heavy with the radio gear in the aft section of the fuselage.

Any concerns going with a 120? Everyone I talked to says "it'll be too heavy", but doesn't seem to be the case.

Please advise,

jldecarlo,

Is that the long or standard version of the uthra thrust muffler?

What prop do you run?

What do you think of it?

I have a Saito 100 in mine and it is almost too much engine. (Can there be such a thing?). I also want to have good fuel economy.

The 120 is too much. I had a Saito 120 on mine and it was too heavy to really enjoy. The Saito 100 is about 8oz lighter with about the same power.

I have a YS91 waiting in the box for mine. I've been kinda slow in getting the thing together due to time constraints. Hope to have it flying in a couple of weeks.

Oooh Boy!

So after READING my manual a bit more on CG location of the DoU3D, I noticed it called for 4 7/8" from LE of CG. (that is quit a bit behind the spar! but I guess if you include the control surfaces, your at ~27%.) With the 120, it was defiantly too nose heavy!

I weighted my OS 120 FS and the Saito FA-100 here at the office this morning at the mail center. The 100 came to 1.2 lbs, and the OS came to 1.8 lbs. (both with mufflers). Needless to say, the 100 is going on the DoMe3D.

Next question, how is everyone setting up there throttle linkage for their inverted 4-cycles? Is everyone using the factory drilled hole and a bell crank, or what? I used a 2-56 rod with a "long" z bend to the throttle arm, but not sure that will work with my 100.

Please advise,

I just drilled a new throttle hole on the opposite side of the firewall, but you could just as easily flip the carb around on the engine. Saito's are made to do that.

4 7/8" CG is super conservative and makes the plane a bore to fly. I flew mine for a long time at 5.5" and it still needed to go back further. I moved that battery back last week and it's at 6". We got rained out last night so I haven't flown it yet.

Hey Coomarlin,

That is exactly what I did a couple nights ago. (Flip carb, drill hole on opposite side)

A friend of mine wrote me and said he has his RX batter by the Rudder servo now! I'm anxious to find out how he installed it.