GIGA 86mm – fin retention

The GIGA rocket has been designed as a true minimum diameter rocket with fin brackets mounted directly onto the casing. This is not a particular KISS approach but rather a result from the “sustainer ready” requirement. Alternatives considered were:

  • Welded aluminium fincan. However due to the lack of availability of matching off-the-shelf materials (it is nearly impossible to find two commercially available tubes to accurately slide over each other) and machining the OD of the casing with the 100bar MEOP was consider not an option.
  • Composite fincan. Downside was time.
  • Both fincan designs suffered an additional challenge – how to retain such a fincan half way up the casing.

Hence the proven NERO through-the-wall fin bracket design was chosen and modified. Changes consisted of:

  1. Matching the 86mm OD casing
  2. Lengthening the bracket to meet the fin design
  3. Increased fin thickness from 2 to 3mm.

KvdL kindly offered to CNC these parts. Especially the 43mm radius is difficult to machine on a conventional mill. Needless to say: the fin brackets came out great! Subsequently FdB offered the use of his lathe/mill combo to accurately, parallel drill the M2 mounting holes in the casing. Finally the fins were cut with a sheer and matched in size on belt sander. ERGO 4203 hydraulic thread sealant was used to mount the M2 bolts into the casing.

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