Aerobatic Configurations

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HeliDev

Well-Known Member
Joined
Jul 7, 2003
Messages
108
Hey all, just tooling around with a few ideas, thinking about aerobatics plane. Nearly all aerobatics planes are biplanes, what about other planforms?
What about a delta, or canard delta planform. You would be able to build a strong light structure with a relatively low wing loading.
Another option may be a tandem wing.
Though this might be an interesting topic to discuss.
 

orion

R.I.P.
Joined
Mar 2, 2003
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Western Washington
Although historically the biplane configuration did figure prominantly in the aerobatic world, virtually all "aerobatic" airplanes used for fun or competition today are monoplanes - several new ones were just introduced within the past five years or so. Some of the names off the top of my head include the Extra series, the Sukhoi models, One Design, etc.

However as one might notice, the one thing they all have in common is that whether monoplane or bipe, they are all of conventional configuration. The reason for this is simple - it is the only safe and functional configuration for aerobatic flight.

A substantial amount of aerobatic maneuvers rely on the achievement of stall or maneuvers at very low airspeed. This is especially true for any tumbling or snap maneuvers where the flow may, and usually does, become partially or wholly detached from the wing surfaces, and this is the primary reason to avoid any tandem or canard configuration for an aerobatic airplane. The canard or tandem wing layout is what's termed as a control limited airplane - in other words, by design the airplane is not allowed to enter into certain portions of its potential flight envelope due to the achievement of an uncontrollable and/or unrecoverable flight attitude. It is of paramount importance that the flow over the main wing never separate - if it does the resultant main wing stall is unrecoverable. That's simply the nature of the aircraft and no-one to my knowledge has ever come up with a solution.

Even the certified canard aircraft are strictly placarded against any real aerobatic maneuvers. One example was the German Speed Canard where in its flight test it was doing a series of simple high G turns. A couple of minutes into the flight the airplane flew through its own turbulence, which accidentally stalled the aft wing. The aircraft went immeditely into a tumble, which continued all the way down into the ground (from 10,000 feet - the pilot bailed out). No recovery was possible.

Another characteristic of aerobatic flight is high rate pitch maneuvers and this is a good reason to avoid configurations like deltas since they will not fly through the maneuvers but will most likley separate off the leading edge and just mush. This is not hard and set since if the rate of pitch is reasonable, the delta may do just fine but since aerobatic flight enters into all the corners of an envelope, the delta may deliver some unpredictable and/or unpleasant reactions to unusual attitudes or flight maneuvers.

One other characteristic of deltas is a very steep rate of drag rise at high angles of attack. In trying to fly aerobatics with this type of wing, a pilot could get behind the power curve very quickly, resulting in an unrecoverable situation if done close to the ground.

In short, there is a good historical reason why aerobatic aircraft, whether bipes or monoplanes, have been of a conventional design - the conventional layout is the only one that is recoverable from just about any flight attitude. A very important requirement for aerobatic flight.
 
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