• The 'lathe" is located in the freezer tray, if low temperature prepreg tow is used.
• The root end extension of the mandrel is placed in the chuck of the lathe and the extension of the tip end is placed in a holder, along with the quill wrap holder.
• The CNC controls the mandrel rpm and thread dispenser movement
• The epoxy dipper tray is placed in the freezer tray. Or manually apply epoxy ahead of next layer, with wiper following the wrapper.

• Consider making the initial mandrel out of water-soluble paper-mache. Then sand down to size.
• Consider making the mandrel out of aluminum. Will thermal expansion cause a problem?
• Consider making the mandrel out of steel.
• Pass hot oil from the root end down the center bore.
• Steel will expand in diameter and in length.
• Use rollers at tow feed location to handle tension from feeder. What about any sag from gravity?
• On production mandrel, consider the idea of having the mandrel diameter slightly undersize then wrap it with one strand of thread, which has be impregnated with a release agent. After curing, draw the thread out first.
• On production mandrel, consider the idea of having the mandrel diameter slightly undersize then covering it with a layer of plaster of Paris. After removing the mandrel, the flexing of the torque tube should break up the plaster of Paris.

• The mandrel must not be allowed to bend under the tension of applying the thread(s). Perhaps have two cam followers; one above and one below the thread that is being wound on to the mandrel.
• The spanwise feed rate of the device paying out the thread must be variable and be vary accurate so that the threads are tight to each other. This may entail trying different diameters of carbon tow.
• Can the same 'thread dispenser' be used for paying out the thread(s) for the pultruded spar.
• Can the thread dispenser pay out a number of threads at the same time. Say, 4 threads to feed one half of the spar pins at the same time, and a greater number for threads to lay down a whole layer of torque tube at one pass?
• It may result in less damage to the threads by putting the tension on the thread by resisting the rotation of the spool(s) that hold the thread(s).
• Pages related to manufacturing torque tube;
• Consider water-soluble mandrel or mandrel where the outer portion is water-soluble (plaster?). See patent US 5,259,901.

Hot Oil Curing:

• Assuming that the mandrel is aluminum (or perhaps steel) so that heat will transfer and the mandrel will expand with heat.
• Hot oil is entered at the end with the large diameter and removed at the small end. The oil will cool as it flows but the large end will require more time to transfer the heat through the thicker wall of the mandrel to the composite winding.
• The expansion of the metal mandrel will provide curing pressure.
• Insulate the outside surface of the composite tube but it can remain rough, since this should help with the bonding of the epoxy to the torque tube.
• Can the oil get all the way to the tip end without loosing its heat?

Back to top | UniCopter Home Page | Nemesis Home Page | SynchroLite Home Page