Thank you for the additional info... I have more questions...
- Is the bottom rail guide removable? **Yes, see next answer...
- What is the backing on the inside of the tube that the 1/4-20 screws thread into? **If you look at the 3rd original pic, which is the motor mount, threaded inserts are located in each of the 3/4" thick plates. Thus if the dumbbell is removed, there are simply 4 1/4" holes in the airframe.
- When flown originally, where was the avionics bay placed? **In the nose.
- The tube in the nose cone appears to be a Giant Leap 7.5" tube or coupler. Can you identify the type and size of tube in the nose cone?** the large portion is 7.5" LOC airframe, as I used coupler for the camera bay that never flew. The smaller portion is 4" airframe. THe voide between these tubes and the cone itself was filled with approx 7# urethane.
- Do you have any other bulkplates, tubes couplers, adpaters, etc... for this size tube? **No plates came with it back in the day. You made your own. As far as the motor mount, since it is based on standard 7.5", you can whip up whatever you want.
Thank you!