101: Workshop Talk: Shear pins and the Marco Polo tracker with Andrew Kleinhenz

Andrew Kleinhenz and the rocket he found with the Marco Polo tracker.

The Rocketry Show gang try a slightly new format for the workshop shows.  We are now inviting fellow rocketeers to the workshop to teach us some of their tips and tricks, and to just talk rockets.

Our first guest is Andrew Kleinhenz, friend to both CG and Gheem, Andrew taught us many of the tricks we have built our rocketry tricks around.   He with us, answers these questions sent to us from listeners of the show!

Shear Pin Questions:

  • How do you figure out how many pins you need?
  • Any issues with the LOC-high power type cardboard tubing and small size 2-56 or 4-40 plastic screws for shear pins?
  • Do you use any reinforcement on the cardboard airframe and components?
  • What size do you recommend? Mid Power, to High Power
    • Cardboard and Fiber Glass recommendations for shear pins
  • Where to place them? 
  • Any math equations or an online calculator?
  • Do you test those with ejection charges first?
Fig. 1. Shear Pin view.
Fig 2. Another view of Andrew’s shear Pin.
The Band of CA used to reinforce the cardboard. Note: The shear pin remains from the last flight is still in the hole. Note the lack of stress around the cardboard airframe.

Marco Polo Tracker

  • What actually is that type of tracker?
  • Approximate cost?
  • Where do you buy it?
  • Difficulty of use?
  • What is the range of the unit?  (How far away can your rocket be from you and still get data)?
  • Advantages of this and disadvantages vs others on the market
Andrew using the Marco Polo tracker to find his rocket in the bean field.
Andrew’s rocket in the bean field…found thanks to the Marco Polo.


Gheem and Andrew on igniters.

  • We had some folks today launching some upgraded BT-55 Goblins today… they used those igniters that came with the package…
  • What would the Rocketry show gang have used?
  • Gheem’s pile of dipped commercial igniters.

    Close up view #1 of one of his dipped commercial igniter.
Close up view #2 of Gheem’s dipped commercial Igniter
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