Category Archives: Rockets

Lvl 3 Payload Bay

Here is my under-construction payload bay. On one side are all the batteries, hooked up in parallel to 2 screws in the center:

The screws poke through to bring the voltage to the other side:

The other plate slides over the posts holds my flight computers and GPS/downlink:

The computers are a G-Wiz Arts and a PerfectFlite MAWD. The GPS unit is a Big Red Bee.

Lessons Learned the Hard Way

This list pertains solely to rocketry. I decided I was going to make a list of every mistake I made that resulted in failure of some kind. My goal is to never make the same mistake twice. I’ll be updating this list every time I make a mistake. Hopefully that will be rarely. On the other hand, “if you want to succeed faster, double your failure rate”. I really learn things when I learn them the hard way. Ideally one makes the mistakes at the unimportant times so that things work when it matters. We’ll see!

  1. Take your time loading the motor and stop and ask if you have any doubts whatsoever. There is exactly one correct way to load the motor. The first flight of Canis Minor failed because the motor CATOed because I loaded it wrong.
  2. Make sure things that shouldn’t come apart can’t come apart. I lost a (broken) camera because the nose cone came loose when it shouldn’t have.
  3. Drill holes in any bulkheads in the booster foreword of the motor. I destroyed Canis Minor because I didn’t do this and it lawn darted.
  4. Make sure your deployment strategy takes the rocket design into account. I destroyed Canis Minor because I didn’t do this and it lawn darted.
  5. Use wadding and deployment bags. I melted the streamer on the Supersonic Aura and broke a fin on landing. I also burned a parachute.
  6. Turn off the electronics if you are working on your rocket on the launch pad. I inadvertently set off the ejection charge when I remove the payload bay to add wadding.

I think that’s it so far. These are mistakes I will not make twice!

"Canis Minor" Launch 2

Canis Minor rocket launch

I built a Performance Rocketry Little Dog Dual Deploy. I have a little video which describes the rocket on youtube. The first launch was a disaster which resulted in a cato. (cato is rocket dork slang for a CATOstrophic (sic) failure of the rocket motor.)

Altitude Plot

The 2nd launch was (mostly) a success! I was going to launch with a J motor but because of clouds I used an H motor instead, so a quarter of the total impulse. According to the sim it should have gone about 2000 feet, but it ended up going about 1500 feet.

Velocity Plot

The rocket wobbled a bit early in the burn. The streamer was supposed to pop at apogee and then the main chute at 700 feet but they both came out shortly after apogee. I think the payload pay just fell out of the booster when the nose cone was blown off. But as failures go, that was a pretty good one, as the rocket descended nice and slow and landed in view.

I was happy with the launch because I loaded 2 motors and they both worked fine. My altimeter worked, too, and fired the deployment charges. My failures were the wobble, which might have been solely because of the slow speed, and the fact that the main deployed too early.

It’s fun.

iPhone launch videos

Finally, here is video of the 3 launches of my iPhone. The first one is the failed launch due to a motor failure. The 2nd is the one where I got all the data that I’ve posted. The 3rd one I got almost no data but the motor performed better as the flight seemed much more normal.

Sorry Elton! Don’t sue me, but I couldn’t think of a more appropriate song.

TRA #012058

I joined the Tripoli Rocketry Association (TRA). This allows me to get certified to buy and fly bigger and bigger rocket motors. If the weather cooperates I hope to do my Cert 1 flight this Saturday in North Branch, MN. I’ll fly one or both of my 29mm-motor-capable rockets, first on a “G” reload kit to make sure I know what I’m doing and then on an “H” reload, which I have to buy at the launch site. If everything works perfectly on my launch they sign my paperwork and I can buy “H” and “I” motors, which gets me up to 640 N-s of thrust. Currently I’ve only ever flown motors with about 80 N-s of thrust.

I don’t know if I will, but if I go all the way and get the Level 3 Certification I can buy motors with 14000 N-s of thrust!

People tend to fly bigger and bigger rockets on the bigger motors. This is obvious, in a sense, because these rockets can’t be flown on smaller motors. For me, though, once my rockets are big enough to fly interesting payloads, such as iPhones and digital video cameras, I’ll be more interested in speed and altitude than bigger rockets. I don’t have the budget or the engineering skill to make really big rockets. I do have the technical chops to do some cool stuff with payloads though.

This is fun!