Item 1225

MAKE: Dragonfly ~ Control - Flight - Spider - Torque Tube

Drawing:

 

Note:

The tube must totally resist the ability to torque. It should allow for a very small amount of axial deflection.

Consider for layers;
  1. One layer of unidirectional fiberglass cloth running in the axial direction. This will 'tie' the tube together and yet it will allow a small amount of 'bowing' in the tube.
  2. One layer of radial wound carbon thread, in CW direction. Overlay it with one layer of radial wound carbon thread, in CCW direction
  3. One layer of very narrow carbon unidirectional tape, wound CW. A second layer of the same except wound CCW. This will give high torsional rigidity and yet give a small amount of low angle cross-ply.

 Consider forming tube over mandrel, then dissolving mandrel. Aluminum dissolved in acid?

Mold the universal yoke into the torque tube and machine the other yoke into the grip stem.

Search "carbon torque tube"

http://www.dfrc.nasa.gov/DTRS/1994/PDF/H-1949.pdf

Search "composite torque tube"

http://www.eng.auburn.edu/research/FF/Deptmnts/Aerospace/sgross/

Outside Information on Ball Splines:

Ball splines provide nearly friction-free linear motion while simultaneously transmitting torsional loads. The path of the bearing balls is straight, not helical, which allows for a very efficient coupling device suitable for a variety of applications.

 

http://www.nbcorporation.com/pdf/keyless.pdf NB Keyless Ball Spline 6, 8 & 10mm shafts

Consider SSPM type Small which is good.

 

http://www.nbcorporation.com/pdf/RotaryBallSpline.pdf Rotary Ball Spline

 

http://www.globalspec.com/specifications/spechelpall?name=BallSplines&comp=144 Specifications

 

http://www.theproductfinder.com/actuator/spltab.htm

 

http://www.nookindustries.com/pdf/powertorq.pdf The smallest one might do

Information on Regular Spline:

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Last Revised: August 29, 2003