What is a Lomchevak, and how is it done?

[Ben74]

hope i spelled that right. can anyone give some info?

[Climate]

It is a maneuver that actually makes the plane fly backwards for a few seconds.
I think it is Chek for headache.

I enter at level flight and about half throttle with my bi-plane.
Pull up slightly to about 45 degrees, and put the left stick in the corner closest to the antenna. Put the other stick to the lower left corner.
This will give you a cross control snap roll. If you time it right, the plane will snap and fly tail first for a few feet.

[rcav8r2]

Originally posted by Climate
.
Pull up slightly to about 45 degrees, and put the left stick in the corner closest to the antenna. Put the other stick to the lower left corner.
This will give you a cross control snap roll. If you time it right, the plane will snap and fly tail first for a few feet.

I've never had one do it this easy. :-) I've done some half @$$ed manovers, but to get a tumble out of my Kougar....

...fly along full tilt and perform an upright snap to say the right.
Let the plane do a snap and a half, and as it is aproaching upside down, move the elevator to full down ( forward)You need to get the timing right, and when done right the tail end of the plane will swing out. Not done yet .... But you do need this before the next "move" If it doesn't do this, bail out, and try again.
Now moved the aileron stick over. If done right you will have a very violent tumble. It looks like someone tripped the plane. I have done this with a few planes with no problems. And there are some that just won't do it. [ besides a trainer obviously :-) ] The 4Star 40 is another plane that does this with ease time and time again. Sometimes these transform into a wingtip spin after the inertia bleeds off. A thing of beauty :-)

Good luck.

[Ben74]

hmm. ok, i guess i'd better ask what a snap roll is then :D

[rcav8r2]

A snap roll is when you are stalling one half of the airplane, or someething like that...

Upright snap to the right- Full up elevator, full right aileron, full rudder.

Upright to the left - Full up elevator, full left aileron, full left rudder.

Inverted to the right - Full down elevator, full right aileron, full left rudder

Inverted to the left - Full down elevator, full left aileron, full right rudder.

Also too much elevator or an incorrect CG will cause a plane to snap. This is BAD :D

BTW 99.9% of the time the CG too far back will cause it to snap, BUT I had a plane that I had too far forward of a CG, and it would snap with too much elevator. Strangest thing. :confused:
It is a Morris Little Boy. Like a dummy I didn't pay attention to the plans when it came time to ballance. It is a Hershey bar wing, so I just ballanced on the spar. I had to add weight to the nose to ballance here. It would snap with too much elevator no matter the speed. Well one day I saw something fall off the plane. It started to fly better, so I thought it was the tail wheel ( ess weight in the tail). Well when I landed I discovered it was the nose weight. I then checked the CG and it was about 1.5 inches further back. I flew it a few more times that day and it flew much better, and had no unwanted snapping tendancies. I then checked the CG on the plans later that week. It was now ballanced as shown on the plans, about 1.5 inches back from the spar. The ailerons on this plane are about 33% of the cord of the wing, about 4 inches. The spar is placed at the high point of the airfiol which does not inlcude the ailerons, so I had a nose heavy airplane that had an unwanted snap. Strange :confused:

[flyfalcons]

Pulling too many G's for the aircraft's weight will make it snap. This is because to get the lift required for that sharp of a turn requires an angle of attack higher than Critical (stall) AOA. The same is actually true for nose-heavy airplanes, as wing loading is actually increased with a forward CG, even if the aircraft weight is the same.


As for snap rolls, the full-scale guys don't use ailerons most of the time. Just elevator and full rudder. I can't seen to get my planes to do that very well, though.

[sukhoi26mx]

Good descriptions.

As a full scale aerobatic pilot (Sukhoi26mx) I can attest that some of the airplanes snap much better with aileron. The sukhoi has a much more aggresive roll rate and more violent (read that quick) departure with pro snap aileron. It also tends to snap much faster if you unload the wing by going forward on the stick slightly immediately after the snap is initiated.

The lomcevak is more of a gyroscopic tumbling maneuver than anything else. I enter it fron a 45 degree up line and do a 1/4 snap (positive) to the left followed by a control reversal to forward stick, full left aileron and right rudder (i.e. outside snap). The torque and p factor take over and the aircraft tends to continue the rolling motion and generally tumbles somewhat end over end. Can be done with very low g (4-6+- ok relatively low g)

It looks much more violent than it is. The only violent part is the controls trying to be ripped out of your hands. Generally exits in an inverted spin.

Sorry for the novel.

Scott

[salmon]

Lomcovák is correct!!!!!!!