U-Can-Do what motor do you really need
 

I have the U-Can-Do ARf. I have it powered w/ a Saito91. My prop is a 15x4W. My fuel is 15/16.

I don't have my wheel pants on. And I didn't mount my cowl. I was waiting to see if the Saito 91 was going to have enough power.

I have 4 flights on it and it flys a little below 1/2 throttle and hovers a little bit above half throttle. Pulling out from a hover is like a freight train, it will pull out but verticle performance is nothing spectular.

So my questions are.
What motor, prop, and fuel combo are you using? How is your vertical pull out of a hover?

I ordered me a 14x4W prop from my LHS but it won't be here until next week. I am hoping that will help my verticle performance.

I have followed all the UCD threads and looks like everybody with the recommend engine range is going through this same situation.

I am probably going to swap to a bigger motor. So I can make the most out of this plane. But I don't know which motor to go to.

I won't spend $270 for a Saito 100 because I don't think the Saito 91 and 100 really differ that much in power. Anyway how much can .01 of a cubic inch really be. I am thinking of going to a 91 2 stroke.

U-Can-Do what motor do you really need
 

My saito 100 is great. I run it on 10% cool power with an APC 15x6 prop turning at about 9500 RPM. Hover is at a little over half stick. I never, ever use full throttle when hovering, tailsliding, or recovering when falling out of a hover -- but I'm very, very confident in my recovery abilities. My model weighs 7 lb even.

I'm used to flying 35% aircraft with power to weight ratios nearing 3:1 and I think the Saito 100 is fine on this airframe.

You might consider an OS 91FX as a budget engine. I've seen it pull a 7.5lb UCD out of a hover with plenty of authority. But it has significantly less power than the saito 100, maybe no more than your saito 91.

Oh yeah, and the 100 is 0.1 cu. in. larger than the 91. That's nearly 10%.

U-Can-Do what motor do you really need
 

I was wrong on my math about a 100 only being .01 bigger, it actually .09 bigger. According to horizon website a saito 100 has a displacement of 17.2cc where the Saito91 has a displacement of 15cc

I really can't see 2.2cc making that much of a differance. If I didn't already own a Saito 91 yes I would buy the 100 just for the little extra power. But 2.2cc is not worth $270 dollars for me to buy another engine. To get may a few hundred more RPMs.

I might just have to move up to more nitro to get a few hundred more RPMs. Since 15/16fuel is $15.95/gallon and 30% is only a few dollars more per gallon it makes more since to me that I can buy alot of 30% nitro for just pennys more a flight to get the extra power I need.

U-Can-Do what motor do you really need
 

To pull out of a hover with more authority I'd try a larger diameter prop first, maybe the 16x4W APC. A smaller prop will rev more, but I think you'd lose some pull.I have a YS91FZ in mine with the 16x4W APC, but I won't be flying it till next weekend. I'll let you know how it goes.

David

U-Can-Do what motor do you really need
 

So what engine do you reccomend ?? What about a ys91??

U-Can-Do what motor do you really need
 

I would recommend the YS 91FZ. I am using it now on my UCD3D. I saw one fly with a OS 91FX. The OS has more HP but it did not fly the plane as well as the YS, especially hovering. I thought about buying and putting an OS 91FX on mine. But now that I have seen the plane fly with the OS 91fx, I am sticking with the YS. I am running a APC 15X6 and 30% Cool power Heli fuel. I have no problem hovering this plane. I added 2 washers for right thrust as well. I added a great deal of tail weight. I must change the tail wheel to a better one.

U-Can-Do what motor do you really need
 

I didn't trust the tailwheel either, it looked like it would rip the rudder out at the first opportunity. I went with a Haigh style wheel, the small one from Ohio Superstar.

David

U-Can-Do what motor do you really need
 

screw it and put a 1.20 on it!!

U-Can-Do what motor do you really need
 

Actually they say in the manual a 120 is too much and hinders the plane 3-d characteristics must be you don't have one

U-Can-Do what motor do you really need
 

Hey man.... I flew the one on the 3dbatix website. Its got a 91, and would EASILY take a 120!!! The only way that it would screw up your 3D is if you made the plane too nose heavy!!! The weight wouldn't hurt it. The wing loading is sooo low, that if you brought it up a few oz./sq. ft., you wouldn't even notice.

And just a suggestion...........NEVER listen to the GP manual for tips on 3D flying.

thorws
 

Hey 3dbatixkid:

So what would you suggest for 3D throws - GP manual says 3" on vator etc... I've got 4" on the vator - 5.25" on the rudder, 3" on each aileron....

U-Can-Do what motor do you really need
 

Just for normal flying I have my low rates set on what the manual says use for high rates. I have about 25% expo on elevator and ailerons. And of coarse I have full throw on rudder.

But the low rates on this bird is pretty effective, if your not used to sensitive aircraft. Low rates will do fine until you get little more comfortable w/ this thing.

I do agree w/ 3dbatix, I can't see how GP says a 91 4stroke is the recommend engine. People w/ YS91 running 30% nitro are wanting more power. This plane needs a bigger motor than a 91 4stroke. Probably a 1.20 4stroke would fly this plane like it was designed to fly.

U-Can-Do what motor do you really need
 

What I do for throws is this:

Get as much out of everything as possible. Then make sure that the ailerons and elevators move equally.

Fly the plane with the maxed out throws.

If when you are doing rolling stuff, ot lamcevaks, and the plane stops flying in the middle of the maneuver, reduce aileron, and elevator a little.

Keep doing this till it flies the way you want.

Then set up dual rates. I do it by cutting the throw down to 50% atv.

U-Can-Do what motor do you really need
 

I would like to hear that a 120 four stroke is a better choice than
a YS 91 from someone who owns a UCD 3-D. And like stated before the OS FS-120 has 1.9 hp@11,000 rpm and the YS 91 has 2.0 bhp@13,000 so I am new at this but it looks to me that the YS 91 is the motor to choose over the FS-120

U-Can-Do what motor do you really need
 

Sly1,

My UCD will be ready to fly this coming weekend, where in NY are you? I'll be flying at the Whitman Flyers field in Bethpage, if you're not far from there you might want to come check out how well the YS moves it.

You wouldn't be the same "sly" who hangs at Fantasia?

David

U-Can-Do what motor do you really need
 

No sorry I am not the same Sly, Also I live in Auburn N.Y near
Syracuse ......But please let me know how the YS91 works..

U-Can-Do what motor do you really need
 

i ahve a saito 120 in mine, this is a pic of teh 3rd flight, cowl was mounted tonight. the plane flys great and 3ds fine. and it will sit still on the runway( in grass) gp says that it won't w/ a 120. i like the way it flys.
thx
chris

U-Can-Do what motor do you really need
 

Sly1,

Weather permitting, the maiden flight will be this Sunday. I'll be sure to post results here right after.

David

U-Can-Do what motor do you really need
 

Well Sly_1, I think that pic tells it all!!!

Engine
 

On those recomending the 120 four stroke as a better choice

I just dont see how you would need it. I have a saito 100 on mine and the plane fly's smoother and 3d's better than some 40 and 33 percent airplanes i have flown. The 100 is to ME the perfect engine choice. It is LIGHT. And it is the perfect amount of power. I admit I do not just rocket out of a hover but I do climb out with plenty of authority. And i am at 3000' above sea level


Here is my setup,

Saito 100
Magnum 2 30% fuel
Apc 15X6 (waiting on my 16X4)
O.S. type F glow plug
Hitec 625's

In my opinion, a 120 is just going to force the adding of extra wieght to the airplane and hinder the flight characteristics. And as someone mentioned before the difference in a YS 91 or a Saito 100 compared to a 120 is not that much.

My best advice (WHICH MAY NOT BE WORTH MUCH)

Stick to a Saito 100 or a YS 91

U-Can-Do what motor do you really need
 

Somehow I don't think that it 3D's better than a 35-40%. Sorry dont think so.

U-Can-Do what motor do you really need
 

What are the specs on the Saito 100 I cannot find them ??

U-Can-Do what motor do you really need
 

Saito FA-100 Specifications:

Bore: 29.0 mm

Stroke: 26.0 mm

Displacement: 1.0 cu. in. (17.1cc)

Weight w/o muffler: 19.2 oz

Weight w/ muffler: 20.8 oz (550g)

Cylinder: AAC

Crank Thread: 8x1.25mm

Propeller: APC 14x8

RPM: 15% Fuel, 2100-9300

HP: 1.8

Fuel: Cool Power 30% Heli Fuel

(According to Horizon)

U-Can-Do what motor do you really need
 

Just got back form the first test flights of my UCANDO.

IT was windy, 18-25 mph or so, so I didn't try too much (this was my first flight in ten years, I was a bit cautious)

The YS 91FZ started easily and I set it kinda rich and took off. There seemed to be plenty of power to go straight up with authority, but I didn't try to hover in that wind, so I can't yet say how it will climb from a hover. I did throttle way back on the uplines and then open it up again and did see it accelerate.

Couple of things... on the first flight the engine backfired and grenaded the plastic spinner that came with the kit. I've got a Tru-Turn aluminum, but I don't have an adapter nut to fit properly yet.

I didn't have any rough landings, but the field was kind of rutty and damp, no sign of the landing gear splaying yet (did a bunch of touch and goes)

Noticed a strong pitch-down couple with rudder input. Gotta work on that one.

Flights were with the APC 16x4W prop, fuel was Powermaster YS2020. Sorry, no tach reading today (still breaking in this beast)

Will post more when I know it.

David

U-Can-Do what motor do you really need
 

Keep us posted !! Sounds good to me I am going to order my stuff today!! YS91FZ is what I have chose to get.