FrancisPerson

I recently recieved a Cub arf from a friend. It has a 79" wingspan and weighs 8 Lbs. As you can see from the photos the engine was mounted high on the firewall and I want to lower the mounting point on the engine by one inch. Is that OK? Who makes this plane as a new cowl would dress up things quite a bit. CG on the spar??? It came with a MECOA .46 and I plan to install a K&B Sportster .65


Thanks
Francis

MinnFlyer

My Feedback: (4)

I'm 90% sure that's the Goldberg Anniversary Cub with an after-market landing gear. It's the best one IMHO. Too bad they built it with the full-size wing.

You can put a 65 on it, but all that will achieve is to make it go higher. That is a lot of wing to get any speed out of.

You can lower the mount, but that will only create more "Up" pull on top of all that lift

daveopam

My Feedback: (9)

Francis, you do realize the plane is set up for an inverted engine mount? I was wondering why you wanted it lower.

David

FrancisPerson

I could put a Davis Diesel conversion head on it. I have dine that to a MECOA .46 before and it turned a 12x8 at very close to 10,000 RPM. I bet a 13x6 would be 9,400RPM; I could bench run and find out.

Francis

MinnFlyer

My Feedback: (4)

Good point Dave

FrancisPerson

I was given the plane yesterday and have made no changes yet, only questions.

Francis

daveopam

My Feedback: (9)

Francis, I still do not know why you want to lower the engine. Let me say this. If you do lower the engine you will never find a cowl to fit it. Plus you are going to have tuning and or siphoning problems with the tank a lot higher than the engine.

David

rc-sport

My Feedback: (12)

Please don't tell me you are going to mount the engine upright sticking out the top of the cowl

MinnFlyer

My Feedback: (4)

[:@]

FrancisPerson

The plane AS I RECIEVED IT had the spraybar (yes the engine stiuck way up) --> higher than the TOP of the fuel tank!!!!! <--- ether the engine must lower or the tank must move up into the cockpit. I plan to install a K&B Sportster .65 which requires the spraybar to be at the SAME level as the center of the fuel tank.

Thanks

Francis

daveopam

My Feedback: (9)

Francis, This plane and engine mount are set up to have the engine mounted inverted. So with the cylinder head pointing down the carb and fuel tank level should be OK. Do you follow me now?

David

FrancisPerson

I repeat I did not build this plane; only recieved it as a gift. That being said I have had limited sucess with inverted engines so any inverting will be diesel. Just so happens I have a Davis head for this engine. I hope to find a replacement cowl as the one it has is rather cut up.

Francis

Grampaw

Having had horses all my life, along with airplanes in one fashion or another, I adhear to the old adage of "never look a gift horse in the mouth." But still, in this case I can't help wondering why your friend gave the Cub away in the first place?

cutaway

The mount in the pics looks correctly positioned to me for a Cub. The tank would wind up below the cockpit windows if its properly sized and installed. What's the real problem here that you're trying to fix? When you start screwing around with thrust lines, you're gonna have to start screwing around with other things too. The F/F power guys have known that for 50 years.

MinnFlyer

My Feedback: (4)

Do you guys realize that you're posting to a thread that was started last May?

I'd imagine that he has solved his problem by now