Ask advice from an expert: improving fiberglass manufacturing

Two events were scheduled for today. The first was a static test of the N-2 rocket motor. In the previous test, the nozzle could not withstand the pressure increase and popped out, so two improvements were made to the test: the groove depth was increased and the snap ring was doubled.

Members keeping their distance from the test apparatus.

As it turns out, today’s test was not conducted. The reason was that there was a problem with the igniter. Since we had not prepared a spare igniter, we had to conduct two tests including this motor in the next test.

In the afternoon, we invited a fiberglass expert to JKUAT to teach us how to fabricate fiberglass airframes. He had originally worked for vehicle industry, where he learned fiberglass manufacturing.

When we showed them the tools we were using, he gave us the following advice immediately.

  1. Use a Fiber cloth (for the outer layer) or Tissue mat (for the inner layer) instead of a Glass mat
  2. Use a 2-inch paintbrush instead of a roller
  3. Use epoxy resin instead of polyester resin
  4. Use mirror graze polish (looks like vaseline) when removing from the mold
  5. Use aluminum for body tube molds, not PVC resin
  6. Use gelcoat for the final layer

The students, who had been engaged in fiberglass production by trial and error, listened to the opinions of the professional.

Students receiving manufacturing instruction. A bucket of water is always prepared for emergencies.
First, apply the releasing agent to the mold
The hardener mixture should be varied depending on the layer. The inner layer should have less hardener (takes longer to cure), and as it gets closer to the final layer, more hardener (cures faster). Specifically, for the inner layer, use 1/4 capful of hardener to 350 ml of resin. In the final layer, use 1 capful per 350 ml of resin.
Remove air bubbles by pressing down with a brush. Work quickly.
Glass mat is made of two layers, like tissue paper, and can be separated into individual sheets. In the production of this body tube, the first layer was for one sheet, the second layer was for two sheets (full), and the third and final layer was for two sheets (full).

Today was also a day of progress for all teams, as the boards ordered from JLCPCB arrived.

Flight control team’s board
Avionics team’s board

11. November 2022
Categories: Nakuja project | Leave a comment

Leave a Reply

Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.