Nosram ; I didn't even bother with the wheel pants or the cowl. Just added weight & they increased the building time that could be used as flying time. My plane doesn't look as good as the others but I didn't buy it for it's looks , I bought it for it's awesome flight characteristics. Later , Rob

When I put my UCD together I noticed the cowell and pants were pretty thin and not the best conscientious fabrication. In consideration of weight, price and the super "G" forces (including landings) I put on this plane mine are showing the stress.....but I am having sooo much fun.

One of our instructors at LCRC club had one and sold it. He said if all you want to do is hover, it'll do that, but he didn't care for it overall. I have seen one and the guy couldn't get his TT engine running long enough to fly it, but it was a very attractive airplane.

Regards,

Just getting my UCD ready to fly - breaking in the engine. The .91 FX runs fine, but when I stop the engine, there is a steady "drip-drip" of fuel out of the carb and the engine floods. Not really a big deal if you know to expect it, but . . .

any advice re inverted engine mounting care and handling?

Leonard

So far I love my UCD. It is a fun plane to toss around the sky and performance is great.

I do however question one of the design charicteristics. It's kind of odd that the UCD was built to use an inverted engine. Yet at the same time the stock fuel tank location almost dictates that the majority of inverted engines will have siphoning problems. Nearly every UCD setup I've seen ends up with a carb that's well below centerline of the fuel tank (especially 4 stroke engines).

People with YS engines or OS pumpers are not effected. The rest of us that had siphoning problems had to resort to cline regulators or perry pumps. In my case with a Saito 100, the cline works wonderfully. The downside being that I had to spend $60 more than I first thought.

The bottom of the UCD directly behind the firewall is tapered to allow the use of special exhaust systems and to vent the air from the cowl. Unfortunately that prevents lowering the fueltank in that location. The tank can be moved back toward the CG if you have an appropriate engine setup.

Other than that I think it's a well designed plane. It's amazing when you consider the following. The fuse is very long and 3 servos are mounted in the rear of the plane and most UCD's still turn out a little nose heavy.

With the coupon you can get a UCD from tower for $175. That's pretty amazing for an ARF this size.

U Can Do 3D will do a lot more than just hover Mind you it wont do it on its own Like any plane, its only as good as the nut behind the stick

I am flying my UCD without a cowl - adds nose weight and complexity in a plane that is not a speedster or a scale design.

I wonder if I could just mount the engine upright?

Leonard

your on to something maybe with alittle tinkering you could just mout the engine upright

Yeah, the UCD is capable of other maneuvers, not just hovering. I'm working on a fun fly freestyle routine with the UCD that will incorporate smooth pattern flying, some slow 3D maneuvers, and other wild aerobatics. I have practiced it once and it was cool watching the plane go through a range of maneuvers, set to music. I am impressed with the versatility of the plane.

Nosram, I have a small stress fracture developing on the side of my cowl. It's in a place where there should be no pressure on it. I noticed when I drilled the wheel pants and cut the cowl openings that the paint and underlying resin was very brittle and flaky. Not sure what this means. Possibly the resin was mixed or set up improperly? This might make it sensitive to vibration?

I should've mentioned that in my above post, but I also feel the cowl is a little weak. When I first got mine I was worried because of the stories of broken wing ribs during shipment, but when I opened mine the wing was fine. There however were a few small cracks in the cowl. Bothing major, but it did show that the cowl was fairly cheap and flimsy.

When I test flew my UCD I flew it without the cowl during the first 5-6 flights so I could have easy access to the engine in case of any problems or adjustments. The plane was ugly without the cowl, but it actually seemed to fly a bit better. Adding the cowl added a little weight which in addition from going from a wood prop to an APC moved my UG forward a bit. I need to move it back just a bit to regain the performance. No big deal, I just need to figure out how to do it without adding lead.

Thin material (fiberglass) on cowl started to break at screws after a dozen flights. I fixed it with laminated rubber/lexan washers.

mt

I usually like to epoxy (with a little glass cloth) small thin metal washers under the cowl where the screws will protrude. This reinforces the cowl sections where most the the stress is concentrated. These also allow you to tighten down a bit more on the cowl screws without cracking the cowl. Also, if the screws loosen, they won't wear through the fiberglass cowl thanks to the washers. I also use nylon washers on top against the cowl (rubber/lexan?... where do you get these?). Might be a bit of unnecessary work on small cowls but works wonders on larger ones. Some also install blind nuts to attach the cowling to the fuselage. CA-hardened holes (preferably in ply) usually suffice.

I make them myself from bicycle inner tube and the plastic sheets I buy at LHS.

I make my screws vibration-proof by overdrilling the mounting blocks and glueing inner-tube Goldenrod to hold the screws (2-56 is perfect for #2 screws, 4-40 for #4's). This works for even the big birds.

mt

Well it finally happened. All the talk about weak landing gear wood finally caught up to me. Letting an expert pattern flyer try out the UCD bragging that it flew like a pattern plane on steroids, he was putting it through its paces doing his pattern routine in about a fifth of the space he normally flys and then upping the rates to roll, hover, etc. (he didn't want to land as he was havin too much fun) brought it in to land and commented how slow it got and put it down like a feather. The idle was up a bit so he zig zagged it to slow it down when it happened, the gear came off. He said in a suprise what the h---l and then the jeers of fellow pilots "he hit the retrack switch." Was supprised to see two 1/8th inch dowells on the front of the block with a small triangle stock on the trailing edge top and glue? not much if any. It came out clean (except for the dowells on the front). I added a large hardwood triangle stock where the short piece was and reglued it back in. I dowelled the block of wood/triangle stock in 5 places through the leading edge wing former. I think this will work as I had 25 flights on the plane before this. One other mod I would recommend to anyone putting the UCD together out of the box is to not use the stock elevator servo cut outs without checking how the servo arm hole and elevator horn height line up. I like my control rods (used 4-40 bb rocket city connectors w/ 4-40 rods) to be in line; not at an angle. The plane flies better and the servos are not strained as much. I also went to pull/pull on the rudder putting the servo in the fuse under the trailing edge of the wing. CG is 6" and still nose heavy. My $.02.
Lou

NOSRAM,

I finally got fed up enough with the tank & siphoning issue after flying the UCD today that I finally moved the tank. I really didn't want to spend the money for a Cline regulator so I had no choice but to make modifications in order to lower the tank. Actually, it turned out to be no big deal and I wish I had done this from the start. The air flow and exhaust channel underneath the fuse right behind the firewall is 1/16th (maybe 3/32nd?) plywood. This plate is simple to remove and exposes the entire tank area. There is one former that needs to be cut some and the side walls of the channel need to be removed. I then glued some new homemade formers at a level in the fuse that also created a ceiling (floor when inverted) at the correct height for the fuel tank. This causes the tank to be much lower than the original location and basically, locates it where the air channel used to be. I then inserted the tank and made a screw down hatch for the bottom of the fuse. This closes up the exposed area. I also epoxied a cover for the hole in the firewall where the tank in the old location exited through the firewall. I made a plywood plate for the lower part of the firewall area (in front of the new tank location) and drilled holes for the fuel line and vent tubing to exit forward. Now the tank is perfectly matched to the inverted carburetor height and is easily accessible by a hatch. Finally, I enlarged to cut out area in the underneath section of the cowl to allow better air flow escape from the engine compartment. This opening is now about three times the area of the cowl's inlet opening but can't be seen when the plane is upright. No more siphon problems and a smoother running engine.

Any chance of doing mine, clearly you have got what it takes. I could let you have it tomorrow

Not a chance. I've seen your building skills. You could have done this in half the time and made it look professional like it was meant to be that way.

well i found out the rudder doesn't hold up as good when engine runs outta fule at 5'
rebuilding rudder now
Chris

How about some pics? I know there are a lot of people that would be interested in doing exactly what you did. How much weight it add?

I thought it simpler to just turn the engine upright. Tank placement's perfect, then. So much so that I suspect that was part of the design evolution.

Even the FS head sticking out of the cowl doesn't adversely affect looks on this plane. (See pic from earlier post)

mt

Just tryin to follow this long thread is making me dizzy

Here's what I've got going on with a UCD3D. I was first going to put a 61FX in it but after asking and reading here on RCU that the 61 will fly it with little power to spare.
I went down to my LHS and picked up a SAITO 100 for some better power, It looks to me that the Saito carb placement won't have a fuel siphon problem.

So now that I have the Saito 100 engine a couple more questions:

1) best if mounted inverted ?

2) should engine thrust angle be set right with a (2) washers under left side of engine mount ?

3) what pitch prop is best for the Saito 100

4) is the stock fuel tank large enough for the engine ?

More questions to follow

Bob

I love the Saito upright. Must admit I've never tried it inverted.

I found the APC 15 X 6 prop works best for me. Getting about 9,600 rpm running a little rich, on 15% FS CoolPower at 1,100 ft.

I just followed the standard instructions for engine mounting...no extra washers.

Fuel tank is plenty adequate for 7-10 minutes depending on throttle settings. A lot of aerobatic stuff with this plane/this engine is surprisingly low throttle. I don't know about you, but after 7-10 minutes of practicing stuff I'm not good at, I'm ready for a break.

mt

Thanks for the reply Kram

So with the Saito upright it seems that the head will stick out and above the cowling quite a bit.

Do you have any pictures of your set-up ? would like to see it before I cut into the cowl.

Bob

1: Yes... inverted fits best... BUT you may want to use a Cline regulator (about $60) to help prevent flooding and smoother running

2: yes (left side fo the plane to provide for right thrust)

3: 15x6 seems the prop of choice

4: Stock tank is fine for about 10-12 minute flights (not sure you could put a bigger on in there...