GIGA IV – Airframe construction

The GIGA III was built completely from aluminium but heavy like a tank. That is probably the reason why it was so successful recovering from non-flight-critical failures. In order to shave some weight for the from the total rocket mass of the GIGA IV it was decided to replace the aluminium tubes with fiberglass (FG) tubes. In the end, to produce accurate custom fiberglass parts, it proved to be a lot of work including fabricating of many custom jigs. Mass density savings FG overs aluminium: 1,68 vs 2,7 gr/cm³. However with the new single parachute design (effectively shortening the airframe) the weight saving of the FG airframe and av-bay coupler tube for GIGA IV was 886gr or a 61% reduction when compared to the GIGA III. Aluminium GIGA III 1440gr. Shortened FG GIGA IV 554gr = weight saving of 886gr.

Notes airframe: 300mm section.

  • 280gr/m2 FG gives a layer thickness of 0,25-0,30mm.
  • ID of 80mm + 12*0,25= 3mm => 12 wraps minimum proved to be sufficient – as-built OD: 87mm.
  • (π*0,086)=0,27m per wrap. 12*0,27=3,24m => 3 piece of FG, each 1,08m long.
  • 0,4 (width)*1,08 (length of FG cloth)*3 (pieces of FG cloth)*280 (FG mass/m2)*0,85 (FG/epoxy ratio) = 308gr epoxy. Based on FG / Epoxy = 1: 0,85.
  • 3 cups of each 70g epoxy / 35gr harder = 315gr epoxy.
  • OD mandel with polyester paper is 79,9mm.

Notes coupler to house av-bay: 132mm section.

  • 280gr/m2 FG gives a layer thickness of 0,25-0,30mm.
  • ID of 76mm + 8×0,25= 2mm => 8 wraps minimum proved to be sufficient – as-built OD: 80,5mm.
  • (π*0,08)=0,2m per wrap. 8*0,25=2m => 2 piece of FG, each 1m long.
  • 0,3 (width)*1 (length of FG cloth)*2 (pieces of FG cloth)*280 (FG mass/m2)*0,85 (FG/epoxy ratio) = 142gr epoxy. Based on FG / Epoxy = 1: 0,85.
  • 2 cups of each 50g epoxy / 25gr harder = 150gr epoxy.
  • OD mandel with polyester paper is 76,3mm.

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