ES CONTROL

My U Can Do 60 is sitting on the shelf. waiting for a engine. I was curious to what a LA 65 could pull. So I used a 78" Goldberg Cub at 7.5 lbs. just like the UCD 7.5Lbs.
I tried 3 different glow plugs and 7 different props 2 types of fuel. My focus was for the UCD. So speed was not what I wanted . The best I could get was around 17 MPH. vertical. ( with out a running start.)

Stock engine - broken in.
Glow plug - med. (tower brand)
Best prop size - 14x4
Fuel - 15% ( Tower brand)

My question is, Could this set up gain more vertical speed on the 65" UCD wing verses 78"wing cub.

( Please note: I do not plan to install this engine In the U Can Do.)

LargeScale88

Yes, I think it could. The piper cub is just not the same as the UCD. I think the UCD is a sport plane, and the cub is not. So you would get way more from the UCD. Any questions, just reply back.

tripower222

My Feedback: (5)

I would say yes however it may be so little you wouldn't be able to tell. There are 2 factors at work here 1st is the airframe drag likely a measurable difference but at such a slow speedit's probably negligable. I dont have a UCD but I would guess it has a pretty thick aitfoil compared to the Cub. The second factor is more likely to yield an increase in my opinion. That is that the cowl on the UCD ismore aerodynamic for the prop slipstreem I am guessing your around 14,000 + rpm on a 4 pitch prop that equates to about a 55 mph wind coming off the prop more of whichthat will be used as thrust not partially disturbed by the cowl.

So to answer your question. aaaaaahh, I think just a little

stevenmax50

My Feedback: (1)

Oh wow.  I dont know what to think of this.  I have a PT60 with the OSLA65 and I ran an 11X7 all last season.  I was getting around 11k RPM.  And I thought I was getting all I could.  14K on a 14X4?  I didnt even know that engine would swing a 14 in prop. 
I do not claim to know anything about prop selection.  I just went by the MFR recommendations when I bought the engine.  I just put a 14X6 on a new magnum 91 4s.  Per Magnums instructions of course.   Where can i get info on the actual prop size range an engine can swing?

ES CONTROL

Be careful !   A 14x 4 pitch prop at low R.P.M. is like a big brake.  You can stall!

ES CONTROL

And 14 " is to long for tri gear

ES CONTROL

I take that back. My Tower Trainer would have 1" ground clearance

tripower222

My Feedback: (5)

I agree

tripower222

My Feedback: (5)

Your right for some reason I looked at the data of a bigger motor size a 14x4 on that may be too much prop.

buzzard bait

Cub vs. UCD: vertical performance is a weight lifting exercise. It will depend on mainly on relative weights, and secondarily, on how much power is wasted from slipstream drag on the airframe. Whichever plane is lightest will go up fastest, unless one really has significantly more drag around the cowl/fuselage/wing root.

Nice to know the 14x4 works well on this engine. I use one on my 4*60 with an OS 70FS. I'm almost always more interested in vertical performance than speed, and low pitch props generally make landings much nicer too. I don't get the famous "float" on landings that others complain about, even though I use the full span wing.

Jim