BOTC84 Launch and Recovery

Test Fitting - BOTC84 Launch and RecoveryThis post will discuss the completion of the BOTC84 launch and recovery subsystems.  It covers items such as launch rails, shear pins, body connections, parachute deployment tests, and rigging.

BOTC84 Launch and Recovery

2 Aug 2018
  1. Rail Button Hardware - BOTC84 Launch and RecoveryI am using launch rail buttons for this rocket. This means that I have to make internal supports (anchors) to hold the buttons in place securely.  One button will be at the bottom of the rocket and the other will be near the center-of-gravity (CG).
  2. The button at the bottom will be the easier of the two to fabricate.  It will be isolated in the fin can, so I can use a block of wood to secure it.  I shaped one side of the block to conform to the inner diameter of the body tube.  I then drilled a hole into it to accept the brass sleeve that will hold the screw and button.
  3. The upper rail button will be in the lower body tube.  It will be in the same location as the drogue recovery gear.  This means this button needs to be in an anchor that will not snag the recovery gear when the chute is deployed.  I carved an anchor from wood.  One side conforms to the inner diameter of the body tube.  The other side is tapered to not give the chute any place to snag the anchor.
5 Aug 2018
  1. Marked the inside of the nosecone and the upper body tube to help with alignment during assembly for launch.
  2. Took a piece of string and wrapped it around the upper body tube.  By folding the string in half twice, I was able to mark four equidistant points on the string.  These points mark where the shear pin holes will be drilled.
  3. Taped the string 1.5 inches below the top edge of the upper body tube.  This is about half way down the shoulder of the nosecone.  Marked four points on the body tube.
  4. Secured the nosecone to the upper body tube with tape.  This will keep the parts from shifting as I drill and tap the holes.
  5. Drilled and tapped the four holes.  Used a 2-56 tap set for the job.
7 Aug 2018
  1. Drilled the holes for the launch rail buttons.  One 1.25 inches from the base of the rocket.  The other button hole was drilled at the computed center-of-gravity, 45 inches from the base.
  2. Epoxied the block built earlier into the lower launch rail button hole.
  3. Connected the upper body tube and the electronics bay.  I taped the two pieces in place and drilled three 1/4-inch holes to receive the connecting hardware for the parts.
  4. Epoxied each side of the connection into their corresponding holes.
13 Aug 2018

Did the deployment tests today for the drogue and main chute deployments.

  1. Charge Rigged for Test - BOTC84 Launch and RecoveryRigged the charges as calculated in the design document and rigged the charges on each bulkhead.
  2. Set the rocket up on the grass and made all connections and installed shear pins.
  3. Fired the drogue charge and the rogue deployed just fine.  I videoed the firing with my SLR and now find I cannot edit them for publishing.Main Deployment - BOTC84 Launch and Recovery
  4. Reset the rocket and fired the main deployment charge.  It was a little strong so I backed it back 0.5 grams and that was much better the second time.
  5. Post Firing - BOTC84 Launch and RecoveryOpened the rocket and inspected the bulkheads and inside the electronics bay for any penetration of hot gasses.  No intrusions were observed.


14 Aug 2018

Attached the motor retention ring to the thrust plate with 6-32 hex head bolts.Motor Retention and Thrust Ring - BOTC84 Launch and Recovery

The rest of the BOTC84 rocket construction pages can be accessed from this link: The BOTC84 Rocket Build

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