Scale BUSA Super Cub

TonyHallo said:

Well the vet was a $700 trip plus $8 a day for special food to dissolve a bladder stone, hope it works. Even after getting two rectal exams at the vet's, cat still didn't want to get into the pet carrier!
Got the plane leveled and balanced checked. The CG is 6.42" back from the leading edge or 30.6% of span. The plans show the CG at 5 13/16 back or 28% of span, I'm happy were it landed.
I think I will run the engine today and set the carb.

Click to expand...

Oooof. We were there a couple of years ago for our cat having bladder stones. $1100 surgery was the end result and now a special food the rest of her life thats $45 a bag and last about a month.

Maiden flight today plus two more, had a dead stick on the maiden, this thing is a floater. I circled the runway from about 150" up flaps down dead stick , over shoot the runway through the parking lot into some high weeds no damage. The two guys that were watching thought I was crazy for circling the runway. I richen the low end twice, the left cylinder is running about 90 degrees hotter than the left. Going to check the valve lash and replace the plug next. I was hoping a little time might help but not yet. Left side 270-280. right side 180-190F. Another great day, blue sky, high 60's, the end is near! Putting the wings on is a real pain in the behind!

Congratulations on the maiden and successful recovery. The Cub look amazing! Too bad about the dead stick. That's one of the reasons I fly electric now.

If putting those wings on is anything like it is with my Super Chief, I feel your pain! I have to hold the end of the wing up with a microphone stand and then wiggle it around until I can get the screw to catch. Took me over an hour the other day! Wish now I'd worked out a better way at the beginning.

Bill,
Ran into Juan Cruz last week at the Warbirds and Classics over Fredericksburg event. He was checking the field over in hopes of hosting a scale event.

It's always the darn aft cylinder that gets hot. I've thought about making an L shaped duct from behind the firewall to help it breathe. Could that cylinder just be getting hot from breaking in?

I feel it is baffled well, using a similar technique on the Champ it runs very cool. It may simply be breaking in as you suggest, the first flights on the Champ were so short I would have not noted the problem.

Is the air leading into the cylinders baffled as well? How about a plenum to force the air through? Seems to me the air would rather go around it than through it as there is more distance to the aft cylinder than the front cylinder. I'd extent the baffling to the air intake ducts. Just some thoughts

So I would say from what I have been taught that it actually isn't all that well baffled. You want to take a full scale approach. What I see is the air is being scooped into the cylinder head top and bottom but has no way of getting out easliy thus keeping the hot air around the cylinders. I could be wrong as I can't see the bottom but from what I see if it were me I would trim away the bottom portion of the baffle so the top is scooping air in and then pushing it down through the cylinder head and out the air exit at the bottom of the cowl.

The firewall is the baffle between high pressure and low pressure. The high pressure side is exposed to the air inlets on the cowl. The low pressure sire exposed to the opening on the bottom of the cowl plus the cheeks on the side of the cowl. Air enters the cowl and passes the baffles to the low pressure side of the firewall.
Yesterday i checked the valve lash and found the left cylinder was a little loose. The intake was .007" and the exhaust was .012" verses .004" and .008" desired.. I also swapped the plugs. Ran the engine in my back yard with the cowl on for several minutes until temperatures stabilized. The left cylinder temp is now 20-30 degrees above the right side. Running 270f on left and 245f on the right side. Going flying today will see what it like in the air. Both plugs were black because I have the low end set very rich.

Great day here in Indiana PA. Nobody is here, five flights so far. Left cylinder 280, right cylinder 220, still got some work to do. During landing the left side drops 245f