Flying Engine Mount Build, Finished

I forgot the launch lug holes!
You won't need a launch lug on this one. Two holes in line through the centering rings is all it takes.

Ideally, the holes should have been punched before the rings were glued on. My rotary punch doesn't allow me to get close enough to the engine mount tube. It'll still slide on the launch rod and launch normally.

The bottom ring was punched. A launch rod was slipped through and turned against the upper ring leaving a mark for the second punch.

Here's how the launch lug fits.
This flying engine mount should be flown with A10-0t or A10-3t engines.
This is a tumble recovery rocket. Call a "Heads Up" before launch.

Flying Engine Mount Build Part 4, Gluing It Together

Notch the tube 1 1/2" from the rear for the engine hook bend.
The lower ring is glued 1/4" from the end of the BT-5.
A wrap of electrical tape goes above that.






Here's how the mount glues together.
While the instructions show the upper ring flush with the end of the engine mount tube, I set it back sto a fillet can be applied on both sides.

The engine block is recessed in from the top of the BT-5.

Use an engine casing to press it in place against the upper bend of the engine hook.

After it is in position apply a fillet of glue through the top.

To protect the surfaces from a dewey grass landing, a coat of Future acrylic was brushed on with a Q-tip.
It's almost ready to fly . . . 

Flying Engine Mount Build Part 3, Engine Hook Notch

The lower ring will need a engine hook relief notch.
Use a rotary punch for a sharp cut round end slot.

Knock off the corner ends with a knife.
The inset picture shows the finished notch.

I didn't realize it until after everything was glued up I forgot the launch rod holes! Punch a hole in each ring opposite the engine hook notch. Be sure the rod holes are in line. (See the final build post for location pictures.)




Before gluing up the mount, brush on some medium CA glue around both ends of the engine tube for strength.

Flying Engine Mount Build Part 2, DIY Centering Rings

Initially the center hole will look rough.
Slip in a BT-5 and shave off any raised edges. Don't take off much, you'll still want a tight friction fit around the BT-5.







It's easier to separate the rings before cutting the outside circle.
The outside circle can be cut with strong, sharp scissors.

Stack the rings and knock off any high spots with 220 grit on a block.








To seal the edges run a bead of white glue around the outside of the rings. Use white glue for visible glue lines, it'll dry clear. Yellow glue dries yellow.

Flying Engine Mount Build Part 1, Parts? DIY Centering Rings

This is a spare parts odd-roc based on Steve Lindeman's Little Me-Me.
Steve's design was a left over engine mount from the Estes Jetliner kit. He upgraded the Jetliner to 18mm engines. The leftover 13mm engine mount was assembled and launched as a spool.

To build it you'll need:
2    5/60 Centering Rings
1    2" Length of BT-5
1    1 3/4" long Engine Hook
1    13mm Engine Block
      Electrical Tape

I couldn't tell the length of the BT-5 engine mount tube. Assuming the cross section drawing from the instructions was to scale, I enlarged the monitor picture until the engine mount tube wass about 1/2" diameter. That gave me the BT-5 at 2" long.

This is a spare parts build. I thought I had all the parts and started looking for the 5/60 centering rings. I have every centering ring except the 5/60 size.
I'll have to cut them from .050" thick mat board.
I did have 50/60 rings.
First trace around the outside of the ring. Trace a few more than you'll need and use the two that best fit the BT-5 tube.
After tracing the outside circle, set and circle a BT-5 in the center.
Use a sharpened pencil so the line is close to the tube sides.
It may take a few BT-5 tries to get the inner circle centered.


Using a new sharp knife, cut the inner circle first.

Cut a little inside the pencil line for a friction fit over the BT-5.
Don't try to cut all the way through in a single pass. Make a few light passes to cut out the center.