I am building a UCD with .91 FX.

It seems to me that the only reason to put a cowl on an engine is for scale-like appearance or for decreasing drag (for speed).

How many fly the UCD without a cowl, and did you mount the engine upright or side mounted.

BTW this should increase engine cooling, simplify fuel plumbing, and help pushh the weight toward the tail.

What do you think?


Leonard
Tyler, TX USA

Very ugly without the cowl. IMHO, the airplane appears to be designed for a cowl and does not look correct without one.

I purchased mine used. The original owner never flew it but did mount an OS Surpass 91 on it. I'm putting a Saito FA-100 on it and mounting it upside down. I'm told this is perfectly OK with this engine. I have the same engine on an Ultra Stick 60, mounted sideways, and that combination works like a dream.

I haven't check the CG yet but the previous owner mounted a little less than an oz of lead just behind and below the firewall. The OS weighs 23ozs with muffler. The Saito FA-100 weighs 20.8ozs with muffler -- I might have to add a little more or shift the battery as far forward as I can get it.

Your OS FX .91 weighs 24.3 ozs with muffler, which according to my calculations means you will be able to balance her perfectly without doing much of anything. That's a lot of engine horsepower for this airplane???

I flew mine for ever without a cowl,it didn't look awful,but was definitely better with it.Hilleja,I had an Os .91 FS in mine,inverted,it worked fine.I removed the cowl because inverted makes the carb way lower than the fuel tank and it gravity feeds fuel to the carb when it is sitting and causes hydralock.I broke a valve spring when it kicked back due to a flooded condition.I removed the cowl so I could put a pair of hemostats on the fuel line when it sits between flights.Also be careful,if you try to turn it over with fuel in the carb,guess where the fuel goes!!Not in the engine,thats for sure.BTW the cg in the book is way conservative,It will eaisly fly at 6 to 61/2 inches back,with no bad tendicies.
Mike

Hey Jim I have never heard of a single person having to add nose weight to a UCD. It's almost always the other way around. Most people have to shift their battery back just to get the CG where it should be. That is why I believe the Saito 100 makes such a good choice for this plane. Not only is it light, it has loads of power.

I also agree that without the cowl, the UCD is pretty darn ugly. I'll leave my cowl off until I have the engine broke in and tuned properly. After that the cowl is definately going back on. Just makes the plane look so much better.

here is my test flight before the cowl was on. flew it 3 teims w/o cowl.

for more pics( one more w/o cowl and one w/ cowl goto
http://www.rcwingers.com/wilkinson.htm

thx
chris

Just picked up one today at the LHS......

I am not impressed at all with how it was covered. I am picky though!

Mine will have a Saito 1.00 in it. (Inverted)

I know it will fly good.

cool wayne, Guess you won't need to fly mine this summer. See ya at the field.

Andy,

I was thinking formation hovering. That'll really piss off the old foggies!

time for a new t-shirt, dude

I am looking for a U-CAN-Do cowl if you have one you are not using E-mail or PM me and I will take it off your hands. Steve

with no cowl or canopy......never took the time to install them.

Steve. I have a spare cowl.

Wayne - My first UCD covering was awesome, this second one blows chunks.....they changed something somewhere. This one looks like it was covered by circus midgets.

Pugs