John's Rocket Blog

There is nothing like the smell of ammonium perchlorate in the morning.

Tag: Frenzy

Testing ejection charges – Part 2

I tested the main deployment charge with 3 grams. (Ignore the narration stating it was 2 grams)

Now that I have my motor casing, I was able to test the apogee charge with 2 grams.

Testing ejection charges – part 1

Tested main ejection charges today. I started with 1gm pyrodex, but that was not enough to break the shear pins. Tried 2 gm pyrodex, same result. Tried 1gm 4FG BP, broke the pins but did not eject the laundry. Tried 2gm 4FG BP, had the desired result. Video

I suspect that the tightly packed parachute is the reason for needing double what the calculation asked for. I suspect that once I get the engine casing(to seal the compartment) and test  the apogee charge, that it will not need to be doubled.

The terminal blocks broke off the aluminum bulk plate.  I had originally attached them with epoxy. I also tried hot glue. I will have to drill a small hole and attach them with a screw because nothing wants to stick to them.


Mounted the primary and backup altimeters to a sled

Lipo batteries are protected in foam rubber and zip tied to the back side of the sled.

Including another photo of the switches on the switch band bulk plate… there are two others not visible in this photo, one for the primary and one for the backup altimeter.

Fins part 3

Mixed up epoxy with low density fairing filler….

measured out the width of the filet with the pipe that I was going to use to smooth things out

applied the epoxy

smoothed it out

and removed the tape

one small drip that would need clean up once fully cured

sanded things out nicely

first coat of primer

applied bondo to deal with a few things I did not like the looks of

Missing is a photo of the fins after the bondo was sanded off….

Onboard camera

Got a cool video camera…. a Mobius Mini Action Camera …. super nice and small

I wanted an outward facing camera this time to reduce drag. I marked out where the lens would look out from the switch band, and drilled the hole (not shown here)

One problem…. the camera has too small of a built in battery. It does, however, accept external power. So I mounted a 1 Ah lipo battery, and a booster/charger from sparkfun. The whole thing is attached to a bulk plate that I made out of modeling plywood.

The micro switch is accessible  via the vent holes. The camera turns on and starts recording automatically once the button is pressed.

The connectors are hot glued in place, so that g-forces do not cause anything to come loose.



Fins Part 2

This happened back in August of last year despite me not posting it until now.

Ugh…. disaster

Thought I’d be clever, and mix up some epoxy with chopped carbon…

load it into a syringe with an extension tube…

And try to inject it for my internal fillets

No pictures of the disaster that followed….. clogged tube, big mess….

Days/weeks later, I slowly finished the internal fillets by a pouring method without the carbon fiber.

New rocket… possible level 3 project

I’ve obtained a new rocket kit, a MadCow Frenzy XL.  I purchased it from Bay Area Rocketry while at F.I.T.S. 2016. It is a 4 inch diameter, all fiberglass, 75mm kit. Preliminary simulations show that it might be a perfect rocket for my home field, as the biggest motor that fits will kiss the waiver. I intend this kit to be my level 3 project. My Gizmo XL could have been that project, but the local TAPs wanted me to get more experience first before considering me for a level 3 certification attempt. So I’ve been flying it on L motors, and it is starting to get a bit beat up.


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