I have ordered a UCD 46 but need help with the engine.

4 Stroke OSFS91II is 2.5grams heavier than the OSFS70 so any reason not to go with the 90 (regardless of price)?.

Can someone tell me the difference also between the OS FS and OS FL engines?

Dude read up on it here http://www.rcuniverse.com/forum/m_817264/tm.htm and here http://www.rcuniverse.com/forum/m_226620/tm.htm

I think the 4 stroke OS 91 will do fine, I have a UCD with a Saito 100 and its a perfect match. You don't use all the power on the straight and level but it had unlimited verticle and you can never get behnd the power curve.
K.O.

Stev

I use a YS 63 in mine with 14 X 4 W apc, but the YS 63 is about equal to the 100 sato, hovers at less than 1/2 throttle. Almost any decent engine proped right will do the job just fine for this floater. Beaf up your landing gear a little, keep the plane light. The 40 does not fly quite as well as the the 60 size, but both are decent. The 100 in the 60 size would be a good flyer. ENJOY

Stevie334, I think you would be happy with either the FS70 or the FS91 on this plane. The 70 will fly it very well and will give good power for about 80% of the stuff the plane is capable of but the 91 will give you power for 100% of the planes capabilities. I flew my first UCD with a Saito 65 and it was by far my favorite plane to fly and relax with, my second UCD has a Saito 100 on it and it's taking a little time to get use to it but both engines sizes have been very fun on this plane.

As for the FL70[:'(][:'(] you might as well just send me the money and let your plane sit in the hanger because that's what your going to be doing anyway if you put that motor on it. One of our club members bought one due to the low price and hasn't said anything good about it in the 2 years he's owned it.
The FL70 has an air-bleed carb so there is no low speed needle valve[&o], it has a non-ringed piston, and it has a plastic back plate.

rmenke, you really think your YS63 has the same power as a Saito 100? My 100 is turning an APC 17x4W at 9600 rpm's, I don't think a YS63 will do that.

I don't know about the OS 4 strokes except they're pretty heavy for the power output. I have a Saito 82 on my UCD 40 and it's great. It hovers with ease and I've never felt a lack of power. Pull out is good enough to be comfortable at 5 to 10ft agl. A friend has a Saito 100 on his and he has much better verticle but that's the only benefit. For my 100 I chose a Twist 60.

I have a UCD 46 with an OS91 4stroke on it that I have been flying for a year. I seems to be about right for the plane. I had a YS63 on it for several months and that worked too. The UCD 46 is a BIG 46 plane that will fly with a .46 2 stroke but not as well as with a .91 4 stroke with 10 lbs of static thrust.

Of course the first choice wud b ys63 being pumped etc also the saito100 is sure the other combo if u pref a simple no noncence fourstroker . if ur the 2stroker kinda guy then a os50 or 61 fx will also suit . better avoid heavier motors that weigh more than the above. and i feel that there is an error in the weights comparision fs70 is 580 gms and the os90 is 680 gms. i have one ucd with the ys63 and the 6v nicad is way back near the servos . so anything heavier up front is a bit iffy.