A couple of aerobatic questions

Matthew

Matthew

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Matthew
OK - so I haven't flown for a week - the weather (although it's beautiful today), my cold, and my budget have kept me on the ground. And I have not ever flown aerobatics.

So, with nothing else to do today, I got to thinking:

Just suppose - a Citabria and Super Decathlon.

During a roll, what are the control inputs during the maneuver?

Same question, but for a loop.

Any differences in the control inputs between the two aircraft during those maneuvers?
 
There are many ways to do a roll - positive G roll, ballistic roll, barrell roll, and straight-and-level precision roll. The inputs are different for each. Depends on what you're trying to accomplish. I could write a short novel on detailed control inputs for all these rolls.

Control inputs for a loop? Pull the stick back. :) There's lots of sublety, but again, it depends on what type of loop you want to - flopped L-shaped loop, or precision round loop?

If you have interest in aerobatics, I would suggest you pick up a copy of Alan Cassidy's book 'Better Aerobatics'. Trust me, it's by far the best acro book out there.

Regarding your Citabria vs. Decathlon question, the control inputs for any aerobatic figure are essentially the same in any airplane. The main difference is in the degree of deflection needed with the elevator and rudder. For rolling maneuvers, the Decathlon will require slightly less elevator and rudder deflection than the Citabria due to the semi-symmetrical airfoil of the Decathlon and its lower adverse yaw.
 
Will you have a symmetrical wing or not? That will make a difference in the control inputs.
 
MachFly said:
Will you have a symmetrical wing or not? That will make a difference in the control inputs.
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In reality, that's not much of a consideration when doing rolls. You learn to fly the airplane, not the type of wing it has. You look out the window and do whatever is required to make the nose follow the path you want. All things being equal, a flat bottom airfoil will simply require a little more forward stick than a symmetrical wing. It doesn't change the fundamental sequence of inputs. Forward pressure is needed regardless of wing type.

Like I said, it's really about learning the airplane. A semi-symmetrical Decathlon wing will require more forward stick to do a level roll than a flat-bottom wing Pitts. An Extra will require MUCH less forward stick than a Citabria. But the fundamental inputs are the same. Only the amount of elevator and rudder deflection varies. In any airplane, you must learn the sight picture of the airplane in the inverted, level attitude. Flat bottom wings are simply a little more nose high inverted.

Matthew said:
What's different then between the Citabria and Decathlon control inputs?
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Citabrias are better for building muscle. :)
 
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I would think the OP is looking for general information on how to perform a roll. No sense over whelming him with several different maneuvers. Just go with your garden variety roll. :rolleyes:
 
Yeah - just trying to visualize the power, rudder, and stick motions to start the roll, bring it inverted, then back out again while staying at same altitude. (And a loop, too.)
 
Geico266 said:
Just go with your garden variety roll. :rolleyes:
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No such thing. ;) But here's the easiest way to do a roll - from cruise speed, pitch the nose up about 20 degrees, neutralize the elevator, and apply full aileron along with enough rudder to keep the ball in the center. Hold those inputs until you're back upright. Neutralize aileron and rudder, and pull out of the shallow dive. It's the easiest maneuver in the world. A non-pilot could do one first try - especially in something like an RV where you can leave your feet on the floor. :) A precision level roll is much more complicated and challenging, even though it doesn't look too much different to the uninitiated.
 
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Matthew said:
What's different then between the Citabria and Decathlon control inputs?
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Actually I never flown a Citabria, so I wouldn't know. A Decathlon can have both chambered wing and a symmetrical one. For example if you have a chambered wing before doing a roll I usually pitch up about 30° (at about 120mph) , then neutralize the stick, and full left or right aileron (also coordinate with the rudder). If you have a symmetrical wing, pitching up would be unnecessary.

Regarding the loop I accelerate to 140mph and do a 4G pull. In order to make the loop round (not egg shaped) I ease off on the top and the airplane does a nice round drop off, as the nose passed 90° pitch down attitude I increase the back pressure again to level at the same attitude.
If you have a symmetrical wing then you won't need to ease off the stick as much on the top of the loop (but you will still need to a bit). If done perfectly you should feel some of your own wake turbulence after the maneuver.


As far as I know a Citabria does not have an inverted fuel tank. So if you want do be able to do negative G maneuvers a Citabria won't do the job. I'd get a Super D if I was you.
 
Matthew said:
Yeah - just trying to visualize the power, rudder, and stick motions to start the roll, bring it inverted, then back out again while staying at same altitude. (And a loop, too.)
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OK - you're talking about a level precision roll, not the roll described above. With the level roll, you start from level flight, do not make a perceptible pitch up before rolling, start the roll initially with coordinated aileron and rudder (in same direction), but after rolling about 30 degrees, you start a smooth transition to the opposite rudder, which steadily increases. As you roll through 45 degrees, forward stick starts smoothly and progressively moving forward. Opposite rudder and forward stick continue to increase as you roll past 90 degrees to the inverted attitude. At 180 degrees of roll, you're at your max. forward stick deflection. Opposite rudder is held as you roll through inverted. As you approach 45 degrees of roll past inverted, you start relaxing the opposite rudder and forward stick. You transition back to your original rudder to keep the nose up as you approach the second knife edge position. Elevator is neutral at this second knife edge position. Rolling through the last 90 degrees of roll, you increase this rudder and start re-applying aft stick to hold the airplane in level flight. Neutralize everything when the roll is complete. If done properly, you will complete 360 degrees of roll without deviating from heading or altitude. A perfect one is quite a challenge, and something few recreational aerobatic pilots can do well. You will be at -1G inverted, so inverted systems help.


Matthew said:
How much effect does the engine have on a roll to the right vs left?
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The difference is almost imperceptible when done from high (cruise) speed. Engine torque is not very noticeable unless you're at very low speed, running a metal prop, and/or have a high power-to-weight ratio (ie. not a Citabria).
 
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Matthew said:
How much effect does the engine have on a roll to the right vs left?
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Insignificant.

If you fly the airplane a lot eventually you will see some difference, but realistically it's engine isn't that torquey.
 
I've helped as a recorder at some contests. I've seen a few perfect rolls, and heard the judges whisper, "Thank you", to those pilots.
 
flhrci said:
What does the metal prop do for it?

David
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Metal props are heavy - high propellor mass in the blades. This produces significantly more torque and gyroscopic effect than a lightweight composite or wood prop.
 
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