For the ST 90, try an APC 15x4w.

(see post #3289 above)

I used to run a 14X7 on my ST G90, cant remember the brand though. My old, old,old , OS 1.08 might be done, after that prop blew off, it hasn't been the same & a lot more slop in the wrist pin/con-rod. Wondering if I should scrap it & put a NIB OS 91 in?

Hi Guys;

I used a 3 deg. Ernst plate as per previous mod posts. The motor looks like it is really pointing to the right. Is this what I shlould be doing or should I start out with the 1 or 2 deg. plates? CG is approx. 5.25 inches.......OK?

Thanks;
Rod

thats just what you want bc, mine is really noticable also

It seems no matter how much right thrust you put in, the Do will go left in harriers. I have to give full right rudder to turn right and it turns like a boat.

UCD #4 hit the ground last weekend in a low hover that was drifting too close to the flight line, since others were flying there I dumped it rather than try flying it out, I dont want to be the first to hit someone. I was having trouble keeping it in the sweet spot mainly because of the up-thrust I put in before the maiden. All my last planes required some, so I put it in while building it, wouldnt you know it was too much for this model to handle, must have been some "incidental" up-thrust already in the firewall or something. After looking at the clean break the firewall had from the fuse, I could see why it came off so cleanly,even the tri-stock on one side was not glued down, I used epoxy & took out the washers on the bottom & added alittle more right, what a difference! At least with full rudder I can now turn the beast in harriers & it hovers way better, very little down is needed, I can hold the hover as long as I want. A little "tinkering" goes a long way sometimes.

so it was front heavy

My CG is in the middle somewhere, about 5.5 " or so. Just removing one washer on the bottom of the mounts made a big difference in hovers, now it stays in the sweet spot without massive amounts of down elevator, who would have thunk it!

yah but you used epoxy so wasent that your wieght of your washer

hi MIXMASTER

I have never in over thirty years of flying seen a normal, front engined model with up thrust.
What is the reason behind this? Most, if not all models require a little down thrust to fly properly.
If you are using it to stop the model dipping down whilst prop hanging you are messing up the model for all other maneuvers.
With a little practice it becomes second nature to blip in a little up elev to hold the nose up. Much better than artificial
trimming.

For me, the up-thrust is for hovers only. I've had several planes that constantly needed up elevator to maintain the "sweetspot",(perfectly straight up), the X100, my first 3 U-Can-Do and a Yak all needed a washer or 2 of up thrust. Its easier to hover for me if I can cut down on the control input needed to maintain it, still have to work most of the surfaces and throttle too, but less is better. It doesnt affect normal flight at all, its only 2-3 degrees at most. Trainers often have a lot of down thrust to compensate for the flat-bottom airfoil that balloons. The ultimate set-up for hovering would be hands off hovering, only one plane I've flown could do that-a foamy from Troy Built Models(discontinued I think)THE MONTY! Too bad it wasnt my plane!!!

Hello guys was just crusing the universe [NOTHING ELSE GOING ON U KNOW HOW IT IS] came across your threads on the UCD thought I would chime in
I have the giant UCD with a super tiger 3250 on it swinging a DYNATHRUST 20X8 prop WHAT A COMBINATION IT JUST KEEPS GOING UP fly aruond on 1/4 throttle will hover between 1/4 and 1/2 throttle with motor to spare for vertical climb out love this plane heres some pics
MADDOG

ok MIXMASTER, I get your drift, but what happens when you progress to the point that you want to do a full program of 3D including prop hanging? Or if you want to prop hang someone elses model?
I promise you that your artificial trimming, whilst logical, will be a diservice later in your flying career.
Almost all models want to dip down in the prop hang. You must learn to control it, not trim it out with up-thrust.
At the end of the day though the choice is yours. Do you want a model that sits there artificially on its own or do you want to learn how to prop hang.

The UCD 60 hover very good without up-thrust, just practice.

Well said Olle, and nice pic.

Thanks!

Looks sharp, can you run with 0% methanol? That would save a bunch of $$ with that hog up front. I buy it from a race track near by for around $3 something a gallon.

Each model is different, some can use it , some dont need it, what ever makes it easier, then you can concentrate on more exciting things, like touching the tail! If you do a lot of hovering DOD with different models, you'll get it. It is a preference, not a must, but if it requires less control input to keep it hovering AND it does not affect regular flying much, it's worth the extra effort. There's not a 3-D'er on the planet that doesnt tweek thrust lines,CG,trim ect..,ect...

agreed, best of luck.

Question ....... Since the can-do has been around for awhile are all the mods from orgional posts required? The one that I am questioning is the main gear mod. I do not see how you can get inside to accomplish this without removing the front wing support ply.
I am asking this because I think that after reading all the posts that GP might have beefed up this area because of all the problems that others have had with the gear failure issue.

Thanks

Hi guys its Elvir from Croatia, I read some of you posts, would appreciate some help I just went to my first F3A event here in Croatia and places 5 out of 7 . I was happy with the result with my tower kaos .I did not know any of the maneuvers until a few day before the event, now I like it . I was planning to do a multi engine but now I have changer my mind. To the guys that fly F3A I would like to build a U CAN DO 3D 60 with a OS 90 4 stroke or a saito 100 , any suggestions on a better combination or a better plane of that sort .. Is 2 stroke better then 4 strokes for the vibrations control in this case as I read in previous posts.

Thank you

tailspins, i have had a UCD60 for 4 years now, on my third one, and beleive me that GP has not beefed up the landing gear block.
you dont have to open up the fuse to do the mod.you just need to drill out two holes alongside where the two stock wooden dowells are, drill for 4-40 threaded rod(or screw equiviland) then thread and fill with 30 min epoxie and screw in the screws, this will strengthen it plenty. notice in the pic how the rods go all the way through the block and out the cooling ramp.

good luck!

I'm flying #4 now and trust me, it needs the gear mounts beefed up. They havent changed a thing, in fact you still get some that have little or no glue down there, my last one broke even though I DID add tri stock & a hard wood block between the formers because it had NO GLUE to hold the gear mount ply down. If that is weak, even the mods dont help much. The only thing Great Planes has changed that used to be a MAJOR problem is the stab, there is harder wood in the stab center, the first bunch were breaking off due to saft balsa. You can get tri stock in the corners of the formers without removing anything, its not easy but I use medium CA and cover my finger tips with a small plastic bag so I dont bond my finger to the plane. Then I add a hard wood block that fits snug between the formers, I push it down as far as it will go, in contact with the tri stock that joins the sides with the gear block. Then I drill a pilot hole thru the gear base and ply mount, then continue into the added hardwood block. I then use a long(about 2" ) wood screw that goes thru the gear base,plywood gear block and into the hardwood block I added inside. This wood screw is in the center of the gear base, between the 2 machine screws that are supplied with the kit.

Gjeffers

Thanks for your input. I drilled the 2 screws like you suggested. I fished some 1/4 ply down into the mounting area and replaced the bolts with 1/4-20 bolts. Since I am using a dubro fiberglass mount I am using 4 bolts ( 2 additional right at the Air channel) also with 1/4 inch ply and some triangle. Then I dumped in 30 min epoxy to secure things.

MIXMASTER

I added that ply like you suggested. Thanks

Thanks to the both of you for giving me help with this gear issue! I'll let you know how the first few flights go this Wednesday

tailspins AMA 1121

No harrier landings or tail touches until you have confidence in the airframe!