My elderly Coverite .40 size Gee Bee Model E usually does snap rolls instead off looping as intended, occasionally does a proper
loop. Somewhat underpowered, lotsa drag with ring cowl, fake Warner engine and rigging wires. I dive to gain speed, attempt loop, it rolls over suddenly at top of loop, either small or large diameter loops. Wings not warped.Right wing droops downward
somewhat after repair. Neither wing is heavy, it's balanced. Plane flys hands off in level flight about 50mph full throttle. Could the ring cowl have something to do with this? Ideas welcome

Maybe if I try a snap roll I'll get a loop

Hi!
Most of the time when an airplane stalls when you loop it is due to the airplane is just to heavy!!!! (too high wingloading)
It could also be that one wing is warped (wash-in in one wing tip).
Or it could also be too much forward CG and too much elevator throw. Fix all these things and your Gee Bee will fly just fine.....
The engine ring has nothing to do with it!


Regards!
Jan K
Sweden

Nice looking Gee Bee, some suggestions. Since I don't know how you have it set up or fly the plane these are some ideas that I would look into.
Check cg, most of the gee Bees will build tail heavy as a model since the full scale had a lot more iron on the front of the fuseladge.

Do the same diveing loop entry. get your speed up then as you pull the plane to level ease the pull so that you are momentarily straight and level but before you loose too much airspeed. Then pull the nose up gently, once you have the first quarter of the loop started start to ease off the elevator so that you have almost no up elevator and you tend to float across the top. you can't stall a weight less airplane since it doesn't need to generate any lift.
Also in any case are you using a little right rudder as you do your loop? Most guys don't. As the P factor and torque become more pronounced at slower airspeeds and higher angles of attack you will need to carry a little right rudder. About the same amount of rudder as you use for take off.
I think you mentioned lateral balance was good but that is in the static sense and a horizonatl mounted engine can still have some effect in flight.

Its too cold to do any flying now. I'm sure others will pipe in.

Sparky

Checked cg, it's ok. Will try suggestions on reducing up elevator and using right rudder around top of loop. I have a Pitts muffler with silicone tubes and squashed brass tube exits to increase muffler pressure to prevent leaning out. Maybe I overdid the restriction and have reduced power too much, will try it without restrictors and see if that helps thrust.

I sent you a PM on the Gee Bee, I have some questions.
Thanks, Barzini

If you're running split elevators, make sure the travel on both halves is equal. I had the same problem on an Extra 300. Mild loops were okay, but hard loops with 3/4 to full elevator produced a snap roll due to a little more travel on one elevator half caused by the side by side dual NyRod setup at the servo. For equal throws, the tubes should have been over/under to eliminate differential travel differences.

Dual, unmatched elevator servos can cause this as well.

I'm talking SMALL differences in throws causing the problem. You really must look at it carefully.

I had the exact same plane from the same kit and it behaved the exact same way. First time I looped it, it snapped out at the top.
I went to low rates and it never did it again.
Good flying little plane but don't get it too slow on final. That's how I lost mine. Repairable but I donated it to a teen member who liked it.
Don't get me wrong, it'll slow down pretty nicely considering the draggy airframe...but don't test the limits too low to the ground.
BTW, mine was noseheavy with a TT46...How about your's?

Mine balances per plan. Right wing appears to be at slightly less incidence than left, hard to eyeball because of the curved bottom of wing. Flies with ailerons set even, no offset. I'm going to try giving it a little right rudder near top of loop, less elevator, etc. as suggested. Plane was designed heavy and has gained weight from repairs and is quite draggy. Takeoffs are sluggish, cruises nicely full throttle gives about 50mph, landings are fairly easy with power on sorta P51 style, slows down quickly with power cut. I'm sure a .60 would pull it through loops easily, may try that later or may hang from ceiling in retirement.

Sorry, I didn't make myself clear....I didn't mean to say that I flew it noseheavy. I just meant that I had to shift the battery pack behind the wing to get it to balance correctly.
Mine flew pretty much the same as your's otherwise. It snapped at the top of a loop and the cure was simply to fly on low rates. I also had to add a very slight amount of right thrust to get it to track straight in the upliine.

Hi!
Many times when I have checked out my fellow clubmembers aircraft having similar problems like yours they have had a twisted wing with wash-in in one wing!
Soo..... have you checked each wing with Robart incident meter..
It could also be checked with the eye-balling metod but you have to be sure of what you do to see it!
As for lopping an aircraft ...everyairplane is capable of doing loops with full power and with full elevator, with no right rudder and no stalling at the top of the loop ......it is just a question of adjusting the airplane /elevator throw. And don't be satiesfied with the CG is as per plan .......always .ry it a little further back ...but do this after flying the plane a couple of times with the recommended CG location. It might fly better with the CG further back and with less elevator throw?!


Regards!
Jan K