Why not just get the MVVS 91 and get power (same as 91 FX if not more on large props), use relatively cheap (5% nitro glow) fuel, reliability, and light weight? Just Engines sells it for like $180 including shipping from England, plus you get to choose what kind of exhaust to get.

This engine would've been my choice if I hadn't gotten my new-in-box Saito 100 for $230 @ Ebay.

MVVS truly makes a great engine and the .91's rear exhaust option looks as if it could be right at home in the UCD. I've had (2) .49's for fun flys and a .77 for my Diablotin Super FG, all w/ tuned slncrs and these engines can really perform. Crisp transitions. It's the engine I would've chosen if I did'nt already have the S.1.80.

was around 6 1/2 with out the cowling or canopy. (Yeah, I am lazy...so!) Saito 100, 9202's all around......It flew like a dream until a buddy splattered it...

The next one will have the canopy, but not the cowl.....

Pug

...omit buddy as well

Are remote needle valves a problem for 3D in general, or just this particular engine? I've always wondered whether needle valve location (length between carb and needle, height of needle vs. carb, etc.) makes a difference. Any theories on this?

I have the 1.60 FX. With the remote NV, there seems to be a delay in throttle response. Some people try putting pump/regulator between the remote NV and carb, and response seems to improve. I heard that the 91 FX's remote NV has more problems than just response: leak air bubble.

If you must use a OS 91 2-stroke, get the 91 SX-H instead. I think it has 3 needle valves for idle, mid, and peak.

Just curious, has anyone else here gone this route with their UC3D? The reasons I went at it this way was:

1. I hate dealing with inverted engines.
2. To eleminate the need for a remote glow starter and a fuelling valve.

Hey there, RCJunky

Any probs with loading up with the engine only 90 degrees turned? Also, which engine - that a .91 or 100, or neither?

Thanks!

-s

Niice looking installation did you use stock motor mount i think i will consider this installation on my YS91 .

Hey Bas -

I have my first Y.S. which is the .91 AC and I'm considering putting in the UCD. Trying to decide whether to use the Y.S. or a Saito 100. Curious - why are you considering putting your Y.S. 90 degrees instead of inverted. I was under the impression that the pumped Y.S. engines didn't experience the "inverted" headaches. That right?

Thanks!

-s

Hi Bas, smartwork.

I have had no problems with the engine loading up. It's the .91 and yes I used the stock mount.

As to using a Y. S. .91 AC mounted this way, I feel that the air chamber on the back may give clearance problems and require too big of a cut out in such a skinny cowling.

Smartwork i am prejudice towards the ys motors but either one will work great. I like the ys because you can mount fuel tank anywhere and it will work . Yes the ys will work inverted i have had numerous installations with it inverted and you dont even need to run a glow system with a inverted ys. I use a remote glow for starting only. The major thing with the ys 91 and all other ys motors they like lots of nitro at least 20% . Rc junky thanks for info i will check it out thanks Bruce

I know that there are people/places that have them but, I really want to support my LHS. This guy really helps out on fun-flys and so on. I ordered it in OCTOBER 2002 and still waiting. I have engine, servos, pushrods, and all the goodies to make most of the mod's but no plane. I will have it ready for spring if I have to scratch build it. HA HA !! Just couldn't read anymore post on it with out saying hello, HELLO.

Smartwork,

I've had a YS 91FZ inverted on mine for some time now. It runs GREAT!!. No need for on board glow driver. I use a remote glow extension for starting the engine. Idles at 1800-2000 rpms and never dies. I fly it with 20/20 fuel and a 16x6 APC prop. Three of us have inverted YS engines on UCD's in my club and we have had very few, if any problems (mostly just getting it adjusted the first time) Great power. Pulls out of a hover easily. I don't think the AC engine should be that much different. I have the tank over the CG (6 1/4" back).

Chris

Hey Chris
Your set up looks good! How much lead to you have on the tail?What oz. servos are you using? I can't make up my mind on the YS 91 or wait for the YS 110.

Doug

Doug,

There is 4 oz of lead on the tail (screwed on underneath in front of the Sullivan tailwheel. I have Hitec 525's on the ailerons and a 605 on the rudder. The elevators and throttle are Futaba S3004's. I use a 5 cell, 6V, 1700 mAh NiCd battery which sits at the rear of the wing. I'll eventually move the battery farther back by making a hatch in the tail so I can remove the lead.

Chris

That weight is with ski's.

I used a Saito 91 w/APC15x6.

Aileron and elevator servo's are Hitec 225's, rudder is a mid mounted Hitec 615 w/pull-pull using Spiderwire, throttle is a Hitec HS 81.

Replaced the hardwood block over the elevator by forming wetted balsa over the original block and did not use the screws or blind nuts.

Battery is 1200mah Lithium two cell pack.

Used lighter engine mount.

No pilot.

I did not use any Epoxy for construction.

I did not use the wheel pants.

I used the 256 rods wrapped in Uni-carbon then soaked with thin CA.

I weighed it at the post office.

Thats about it.

Darrin C

After a LONG time on back order, my LHS called today to say my UCD was in. I am on my way to go get it.

Check that wing real good for broken ribs. It may look ok but take both hands and gently push on both sides of the wing ribs. If they give inwards there broken for sure. I didnt realize this until I had already cut the covering away for the aielrons and I could then see the broken ribs through the openings. Then squeezing the others realized all but about three were also broken. Just a warning.

Ron

Just out of curiousity, for those of you who have the same setup as me (UCD with Saito 100), is there any way of taking the cowling off without needing to take the muffler off the engine? I guess I could cut some kind of slit in the cowl, but that wouldn't be too asthetically pleasing.

This is my first plane with a cowl. Seems like a hassle to take the muffler off every time you want to get under the hood.

Disassembling the muffler is not that bad if you have the right wrench. You have the 2002 version of the Saito 100 right, one with a straight manifold and a rotating muffler, not like the old style w/ bent manifold.

Muffler, header and needle valve all have to come off for the cowl to have the least amount of carnage - dont try to stretch it or the gel coat will crack (yes, speaking from experience). Agreed, its a PITA, but it sure looks nice, worth the extra minute to do it. I have the straight header, I found the header pipe goes on nicely through the cowl, and a deep socket (I think its 14mm) to tighten the jam nut, then screw on the muffler to the header, and wrench the nut on the outside. I do like that the needle valve fits outside the cowl without having to add a piece of piano wire to it...

Yes I have the new version with the straight pipe and the rotating muffler. And yes the nut is 14mm. I was planning using a 14mm deep socket like dessartrat suggested. Then a 14mm open ended wrench on the outside nut.

My needle valve fits nicely inside the cowl. In fact, I had to add a 3/4" piece of piano wire with an L shaped bend in order to extend it out of the cowl. I made it so the L is barely out of the cowl and I do not need to fuss with it in order to take the cowl off. I don't even need to flex the cowl in order to get it over the wire. I'd say the wire ends up being 1/8" past the opening I drilled into the cowl. That ended up working out great. I'll try to upload a picture of it when I get home.

The reason mine fit inside the cowl is probably because I did not rotate the carb like some of you did. I just redrilled a hole for the throttle linkage opposite the one that was standard.

I have the same set-up (Saito 100 in the U-Can-Do) and just completed putting it together. Are you guys using anything special on the header/muffler threads? A thread in the Engines column prompted a few responses from Saito owners, to use teflon tape or an automotive anti-galling compund - in response to Saito's recommendation to oil the threads.

I use teflon tape, seals great and doesn't come loose.