2.6" Tomach Build Progress: Fins

Since my last update, I've done the "tip-to-tip" fiberglass on one set of the fins. This should provide an unnecessary level of strength to the fin joints for high performance flights or hard landings.

I'm using 6 oz./ sq. yrd. fiberglass cloth, and I am doing two layers. The first layer is a bit smaller, and the second layer covers the entire fin and airframe tube surfaces.

I used the tape to mark where the smaller, inner piece of fiberglass goes.

The inner pieces cut out from the template that I made from paper.

I used some epoxy with tiny pieces of fiberglass mixed in to first fill the fin/airframe
tube joints. Then I added the small piece of fiberglass and wetted it out with West 
Systems epoxy. Once the smaller piece was wetted out, I removed the tape and 
laid the second, larger piece of fiberglass on top. That was wetted out, and I 
improvised a way to keep the fiberglass down in the joint of the fins and airframe
 tube. I used the brass rods on top of the peel-ply with some rubber bands, then
 applied some weights to the whole setup for curing.

Showing the rubber band pulling the brass tube into the fillet area.

The weights piled onto the brass rods to keep the joints tight while the epoxy cured.

Fiberglass trimmed around the fins, and the weights removed.
The brass rod and weights technique seemed to work quite well,
with only two small spots that look like air got into the joint.

6/10/18 - Sport Launch in Geneseo

I attended the June sport launch in Geneseo. It was a much calmer launch than NSL two weeks ago, with only a couple dozen flights in the time we were there. The weather was nearly perfect, with light and variable winds. Overall, it was a fun and relaxing day for rocketry.

I did two flights and put together videos with ground views from my phone, pad videos from my GoPro, and onboard video from my Mobius:

First, I launched my X-Calibur on a CTI H87 Imax. It reached 1748 feet and had a perfect recovery. It landed only about 200 feet away.

Then I launched the Eclipse on an Aerotech I327 Dark Matter. It reached 2042 feet and landed about 400 feet away. It showed its characteristic wiggle on the way up, which is visible in the ground videos.

Tomach 2.6" Build Progress: Electronics Bay, Nose Cone, Motor Mount

I've gotten a good amount of work done on the Tomach since the previous posts.

The First Time Fitting Everything Together!

Electronics Bay:

Updates since the last time:

• Electronics sled is finalized (assembled and layout complete)
• The bulkhead plates have been JB Welded together
• I have also installed the "switch band" (the small piece of body tube that attaches to the electronics bay
• I have installed the forward tube retention hardware

Work needed to complete electronics bay: Install wire for the e-match attachment points into the bulkheads. Drill the two air sampling holes/altimeter arming holes.

Electronics Bay: JB Welding the Switch Band

Switch Band Taped in Place while JB Weld Cures

Hex Nuts JB Welded in Place for Forward Tube Retention

Nose Cone:

The little bit of work that was needed for the nose cone is complete.

• The bulkhead is assembled with an eye bolt and epoxied into the nose cone coupler
• The nose cone coupler has hex nuts JB Welded in place, in the same manner as the electronics bay. This will allow for secure nose cone retention as well as simple access inside the nose cone if needed.

Hex Nuts JB Welded in Place

Looking Inside the Coupler to the Bulkhead

Completed Nose Cone
(Note the black screw that is visible.
There are two that hold the nose cone to the coupler.)

Motor Mount and Drogue Recovery Harness

A decent amount of work was done here as well since the previous update.

• I built up a third "centering ring" with masking tape that aligns with the forward end of the fin tabs. This is to prevent the future internal fillets from leaking all over inside the motor mount.
• I placed heat shrink tubing in place on the Kevlar recovery harness at the end of the motor mount tube. This will prevent fraying over time during descent when there is tension and vibration on the harness.
• I also applied a combination of electrical tape and heat shrink tubing on the Kevlar recovery harness at the exit of the body tube, for the same reasons as above.
• The motor mount has been JB Welded in place in the main body tube.

Work needed to complete the motor mount: Fin installation and internal/external fillets.

The Masking Tape "Centering Ring"

Showing the Alignment with the Fin Tabs

Motor Tube: Recovery Harness Protected by Electrical Tape and Heat Shrink Tubing

Aft Airframe Tube: Recovery Harness Protected by Electrical Tape and Heat Shrink Tubing