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Design Notes

Model Rocket Design Notes

Dimensions

Engines

Type DiameterLengthCasing
MicroMaxx 6.3mm26mm1mm
Mini 13mm45mm1.6mm
18mm 18mm70mm2.6mm
Tube Inside Dim.Outside Dim.Length
  mm/inmm/incm/in
MM Stand 4.00 / 0.1574.50 / 0.1771.35 / 0.53

Body Tubes

Tube Inside Dim.Outside Dim.WallCircumference Estes ODASP OD
  mm/inmm/inmm/inmm/in   
T-MM 6.45 / 0.2547.16 / 0.2820.35522.49 / 0.886  7.1
T-10.5 10.72 / 0.42211.38 / 0.448 35.75 / 1.41
BT-5 13.2 / 0.51813.8 / 0.544 43.35 / 1.707 13.713.7
BT-20 18.0 / 0.71018.7 / 0.736 58.75 / 2.313 
BT-50 24.1 / 0.95024.8 / 0.976 77.91 / 3.064 
BT-55 32.6 / 1.28333.7 / 1.325 105.87 / 4.168 
BT-56 33.1 / 1.30434.2 / 1.346 107.44 / 4.230 
BT-60 40.5 / 1.59541.6 / 1.637 130.69 / 5.145 
BT-80 65.7 / 2.58866.0 / 2.600 207.35 / 8.163 

BT-5 to T-MM downscale is 51.88%.

Electronics

Jolly Logic Altimeter Two

  • 49mm x 18mm x 14.5mm (diameter 23.114mm)
  • 9.9g (0.35oz)

Stability Notes

Stability (CP-CG) should be 1--2 caliber.

Velocity off rod should generally be at least 15 m/s (very rough rule of thumb).

Component Notes

Nosecones

Nosecone plug should be approximately the diameter of the tube.

Couplers

Coupler construction video from Apogee.

Tube couplers should be ~2x the diameter of the tube.

  • At what power levels?

Fins

Orient grain of balsa wood along leading edge of fins.

Engine Retention

Minimum diameter engine hook

There's a motor retention technique for minimum diameter rockets shown in Tim van Milligan's book that uses a piece of piano wire bent into three sides of a rectangle, two long sides and one short, where the short side goes over part of the bottom of the engine, staying clear of the nozzle of course, and the long sides are buried in fin fillets. I've started using that method on larger than minimum diameter rockets, with the ling sides going through pinholes in the aft centering ring. It seems like that should work nicely for MicroMaxx.

Recovery Systems

Parachutes

Parallel shrouds may prevent tangling:

Parachute Shroud Patterns

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Recent Changes (All) | Edit SideBar Page last modified on July 09, 2021, at 07:45 AM Edit Page | Page History
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