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Tumbling

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Old 08-04-2009, 01:05 PM
  #1
BsSmith
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Default Tumbling

Does anybody know how to tumble an RC airplane? The only place I have seen any airplane tumble is during full scale airshows. During one of the tumbles it seems like the pilot hits full right rudder and then full up elevator, but then when I try this in Realflight it doesn't tumble.

I do not have a 3D airplane in the real world, but there was a Super Declathon at Oshkosh this year that did a tumble, so you don't need an extremely high performace airplane to do this, only a large rudder.
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Old 08-04-2009, 01:13 PM
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exeter_acres
 
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Default RE: Tumbling

start here

http://en.wikipedia.org/wiki/Lomcevak
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Old 08-04-2009, 02:52 PM
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daveopam
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Default RE: Tumbling

The only plane I have that will do it is a Goldberg Ultimate. It will go end over end 2-3 times and then loose momentum. I do it as follows... Full throttle level pass, pull up to a 45degree climb and cut the power. I let it climb for 1-2 seconds to scrub a little bit of airspeed off. Then as fast as you can give it full down, full left aile and full right rudder. (same thing used for a flat spin or blender with an Ult) After the first tumble you can add some power. This will get the third tumble out of it most of the time. Make sure you have some alt because the plane will be dead in the air when it's done. The nose will fall over and you can add power and fly out, but you will loose about 50'. A word of caution. This is a very violent maneuver. I tore the cabane out for the top wing twice doing this with the kit version. I now have the ARF which has doubler's in that area but I still scrub some speed off first. Blenders are even harder on the airframe so be care full here two. These are not for the faint of heart with an Ultimate.
The main thing with model planes. They are so much lighter they just don't have the momentum to carry through some of these maneuvers. A full scale Extra 300 for example will go 1600 lbs or so. A 1/4 scale Extra is what? 15-20lbs? The resistance of the air is just going to stop the rotations sooner.

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Old 08-04-2009, 11:07 PM
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Default RE: Tumbling

There are a number of factors involved getting a plane to tumble including but not limited to, CG location, control size and travel, and as Dave mentioned above, overall weight. My Aeroworks Extra 260 will tumble but it has a VERY aft CG (it's setup for 3D) and 45 degs of elevator throw with 53 degs of rudder travel. Good luck at getting the tumbles figured out.
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Old 08-05-2009, 12:00 AM
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Default RE: Tumbling

from my experience heavier aerobatics airplanes tumble easier than most of todays modern light airframes, heavier planes fly better in windy days too...
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Old 08-05-2009, 12:57 AM
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Default RE: Tumbling

All of the above,just start going for it up high and see how it reacts,adjust to taste.
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Old 08-05-2009, 02:46 PM
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Default RE: Tumbling

I should have also said. I was told most planes react to the inputs I described better from a knife edge climbing at 45 degrees. I think it is supposed load up the airframe before the oposite inputs are slammed in.Don't know if that's true or not. These things are so violent I don't do very many and have never tried it from the edge.

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Old 08-06-2009, 10:13 AM
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Default RE: Tumbling

The best-tumbling plane I've ever seen is the Seagull Extra 40 ([link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGPL7&P=ML]this one[/link]). That plane would tumble instead of snap. Small control surfaces but an effective rudder and thin wings will give you snaps, and the heavy wingloading lead to good tumbles. A guy that had been flying for right around 6 months, this was his third plane, and he was doing tumbles 30ft above the ground at full-throttle parallel to the ground after 10 flights. He told me to try it, and it was as simple as doing a snap roll. He had an OS 46AX in it and standard servos. I know tumbles are CG-dependent, but I have no idea what the GG was....sorry.
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Old 08-06-2009, 02:09 PM
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Default RE: Tumbling

The moment of the plane (or its overall length) will also greatly affect its ability to tumble. Airframes with a SHORTER moment will generally tumble better. Typically I would put my planes into a straight vertical climb, pull the throttle back and right before the stall give it full down elevator and full throttle (might mix in some rudder).

A biplane such as the Pitts or Christen eagle will tumble VERY well. Caps, Edges, and others with a shorter moment for an acrobatic plane also tumble well.

The other approach is similar to a blender but I warn you in real life there is a posibility you can tear apart your plane if you enter the maneuver too fast or if there is any structural issues.
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Old 08-06-2009, 05:45 PM
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Default RE: Tumbling

To add to the last comment by airborneSGT, I watched a fellow tumble a 50cc Edge and bent the wing tube so bad it couldn't be removed without cutting it off on one end. There was nothing wrong with that tube beforehand so as mentioned previously it's VERY hard on the airframe. He was lucky to get that Edge back on the ground and the wings had more dihedral afterwards than any trainer I've seen, kinda like daveopam's cabane tearing out of the top wing. Tumble's can be pretty violent and destructive.
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Old 08-07-2009, 03:06 AM
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Default RE: Tumbling

Anybody have a video of this manuver. From the descriptions, I may be doing it inadvertently while trying to do something else... atleast on the sim.

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Old 08-07-2009, 09:32 AM
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Default RE: Tumbling

Here's a good tumbling video:
http://www.youtube.com/watch?v=PmRWRo-CrUY
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Old 08-07-2009, 09:46 AM
  #13
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Default RE: Tumbling

That's a pretty cool vid!
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Old 08-09-2009, 03:20 AM
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Default RE: Tumbling

How about [link=http://www.youtube.com/watch?v=JcNFzektfDg&feature=channel_page]this one[/link] ? Starts at 0:25.
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Old 08-09-2009, 10:28 AM
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Default RE: Tumbling

That's more of a shallow snap. Tumbles involve end over end and flipping on a changing axis. The video you posted just skews his axis of rotation. It's a very IMAC-style snap-roll.
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Old 08-10-2009, 04:16 PM
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Default RE: Tumbling

I have a tower uproar with a very light wing loading (14oz/sq ft.). It will tumble, but it is difficult to do and requires that you enter from a hard positive snap. The inputs are as follows.

1. Hard up elevator at high speed (level or slight climb) 2. simultaneous left rudder, left aileron and full throttle 3. down elevator. Hold left ail/rudder, full throttle, and down elevator and the plane will do 2-3 flips before it loses energy and falls out of the maneuver.

The three steps should be done in a quick 1-2-3 count that takes a little less than a second. The idea is to hit the down elevator roughly when the plane passes through knife-edge attitude. The maneuver has to be done fairly violently or you will just end up with a lazy corkscrew. Heavier planes with big control surfaces can probably omit the snap entry and tumble straight from a climbing knife-edge attitude.
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Old 08-12-2009, 08:49 PM
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Default RE: Tumbling

I saw someone at the field do a Lomcevak, so I asked him the stick inputs and tried it with my 60.5" ultimate bipe. Come across the field about half speed and quickly threw all sticks to the upper left corner. It spun so fast it scared me. It IS a very violent maneuver. And about the most impressive I've seen my plane capable of. Start high and not too fast and you'll be okay.
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