Springs for all-moving fins and tailplanes

Hello there! I had an idea I wanted to put out for people to discuss. On the back end of an airplane, it's easier to construct the fin and tailplane as single, all-moving surfaces. However, pilots say that airplanes fly better if the tail consists fixed fin and tailplane, with the rudder and elevators constructed as seperate, moving parts.
It occurs to me it would be almost as simple to build as the first case, but incorporate the advantages of the latter, if strong return springs were incorporated into the all-moving surfaces. These springs would tend to return the fin or tailplane back to the approximately straight ahead, neutral flying position. This would give the airplane the same feel and safety to the pilot, with easier construction.
If I were building it, I would make the mounting points for the springs adjustable, which would provide an easy way of setting trim.
If there is some flaw in this scheme I'm overlooking, please correct me. If, on the other hand, my insight turns out posess the inspiration of genious that saves time and effort for homebuilders everywhere, I'd be delighted if people used it. There is no charge but your endless gratitude...
Thanks for taking the time to read this, Charles Meredith Brown, Clearwater, FL.

Take a look at Steve Wittman's airplanes Charles. I guess great minds think alike!

I suggest that a read of the classic text Airplane Performance, Stability and Control (available through Amazon.com and other outlets) will offer some insight as to why the tail sections of airplanes have evolved to be what you see around you. Springs dilute control feel in undesireable ways and create stability and flutter issues if not applied carefully in aircraft flight controls.

The all moving, or flying, control surfaces have more mechanical issues than are obvious. Both Piper and Cessna tried them. Cessna chose to return to fixed horizontal and vertical surfaces. Piper still sells models that use them but new designs have fixed stabs and vertical fins.

Best of luck,

Wes
N78PS

I have flown Piper, Cessna and Beechcraft with "all flying tails" ( called STABILATORS). Got my IFR in a musketeer. All stable and forgiving. In order for it to work, an ANTI-SERVO trim tab is used in all of them. Include the Thorp T-18 too. All the Zenith designs by Chris Heintz have a FULL FLYING rudder. The anti-servo tab is used to give it "feel". so does the "over hang" on the Heintz designs.

Only helicopters with hydraulic boosted controls use springs or bungies. Gives it an artificial feel. In those, if let go of the stick, it would fall over to one side.

Bob

Quote:

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Originally Posted by WLIU

I suggest that a read of the classic text Airplane Performance, Stability and Control (available through Amazon.com and other outlets)

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This book is sometimes known as "Perkins & Hage" for the two authors and is "the book" for aircraft stability and control. I used this in my junior year of aero engineering school, so you'll need to have a fairly good engineering background to understand the material. Although first published in 1949 the material is still relevant today. Additionally, the end of each chapter includes a suggested reading section which mostly references NACA (national advisory committee on aeronautics, the fore runner of NASA) reports. NACA reports will allow you to dig deep into the subject. These reports are available on-line in a number of places including:

http://naca.larc.nasa.gov/

http://naca.central.cranfield.ac.uk/

http://www.sti.nasa.gov/


Cheers,
Kurt

Quote:

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Originally Posted by Bob Dingley

All the Zenith designs by Chris Heintz have a FULL FLYING rudder.

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So does the Evans Volksplane.

So does my Nieuport 11.

Thanks everyone. Thought I had a great idea we could all use. Looks like the spring wouldn't help things at all. Take care.