Failure to Launch
October 12, 2018 1:58 PM   Subscribe

Last week, I took my youngest daughter to launch model rockets, and things did not go so well. Please help me diagnose what we did wrong.

The last time I launched a model rocket was about ten years ago, and I was using a different launcher, so there is that. Here are the relevant details.

I think we did everything we were supposed to do:

1. Put the Estes engine in the rocket, and put the rocket on the launch pad.
2. Inserted the starter in the rocket engine, inserting it as deep as it would go.
3. Inserted the plug into the engine to hold the starter in place.
4. Connected the leads from the launcher to the starter, making sure wires did not touch.
5. Inserted the pin into launcher. The light came on to show a good connection.
6. Pushed the launch button.

We tried about two-dozen times, and we only had one successful launch. We swapped out engines and starters, and nothing.

Ten years ago, with my older daughter (and a different launcher), we never had problems like this. I am sure I must be doing something wrong, but for the life of me, I cannot figure out what it is.

Thanks, as always, for your help.
posted by 4ster to Grab Bag (12 answers total) 1 user marked this as a favorite
Were the batteries fresh? I had a similar experience where the batteries were strong enough to light the ready light but not enough to ignite the igniter, and after swapping in new batteries had a series of successful launches.
posted by Reverend John at 2:01 PM on October 12, 2018 [1 favorite]

Response by poster: Brand new batteries, but a great suggestion I had never considered.
posted by 4ster at 2:03 PM on October 12, 2018

This might be a really basic question, but did you push and hold the launch button, or just push it momentarily? It’s probably been a couple decades since I launched model rockets, but I remember the rhythm well - key turn, countdown (for fun and science), push and hold button, rocket takes off a few seconds later.
posted by shapes that haunt the dusk at 2:12 PM on October 12, 2018 [2 favorites]

Not only do they need to be fresh, they need to be name-brand. I had this problem once with off-brand batteries; swapped in some Duracells and it was fine.

Even better would be to rig up a custom launcher from one of those 12v 7ah gel cel batteries that you get in UPSes and kids' electric toy cars and such. More than enough juice in one of those puppies.
posted by Anticipation Of A New Lover's Arrival, The at 2:12 PM on October 12, 2018

Also, if I’m remembering my summers at model rocketry camp, once a rocket has failed to launch, you need to put in a fresh starter. I remember the starter burning out even if the rocket didn’t launch. Does that sound right to other model rocket people? Engines and starters can be duds, but either way a failed launch usually needs a fresh starter for the next attempt, right?

Again, this might be something you were already doing, but I figured I’d ask just in case.
posted by shapes that haunt the dusk at 2:26 PM on October 12, 2018 [4 favorites]

I seem to remember the igniters going "stale" if they were out of the package too long. What's the humidity situation like where you are? Could your starters or engines have been sitting on the hobby shop shelf for too long?
posted by contraption at 2:29 PM on October 12, 2018

Have you tried setting everything up except the rocket, and seeing if the starter ignites? In other words, attach the wires to the starter, place it somewhere safe, and push the button.

It's been over 30 years since I've done anything with model rockets, so maybe this testing procedure isn't possible. But that's what I'd do as a first step in trying to figure out what is going wrong.
posted by Winnie the Proust at 2:43 PM on October 12, 2018 [2 favorites]

If i recall it could be old igniters or old motors. Either of those true? (Old can be months if it's really humid by you)
posted by chasles at 2:51 PM on October 12, 2018

Damn it! Too late to this AskMe, most everything I would have suggested has already been suggested. Someone even already suggested a igniter-only ignition test.

It would be helpful to know the condition of the pyrotechnic material on your failed igniters after you removed the igniter from the engine after a launch failure. Was the pyrotechnic material burned through but the propellant did not ignite? In that case it's likely the igniter was not touching the solid propellant. Was the pyrotechnic material not burned through? In that case there was likely a problem with your electrical power subsystem. The only suggestions I could offer there besides what has already been suggested would be to clean the contact points of the micro-clips where they grab the wires of the igniter, and ensure the micro-clips are making good electrical contact with the igniter wires as per the Estes document Igniters and Their Use (pdf). Also here's a copy of the Apogee Rockets document How to Minimize Igniter Mis-fires (pdf) that might also be helpful to you.

Eponysterically yours,
posted by Rob Rockets at 3:48 PM on October 12, 2018 [13 favorites]

Perhaps a bigger battery, trying to remember but I think we used small car batteries. A motorcycle might have more kick and be portable. (kick being current)
posted by sammyo at 12:20 PM on October 13, 2018

A good diagnostic test would be to attempt to light another of the igniters in the same way with the same equipment but not in an engine or rocket and observe what happens. Does it get hot? Does it ignite? Change one variable at a time and test and observe. If your goal is to introduce her to science than this could make an interesting set of experiments.
posted by The Violet Cypher at 6:27 AM on October 14, 2018

Response by poster: Hi everyone. Thanks for the help so far. I bought the kit at a Michael's craft store and used it within a week. I actually unwrapped the engines and igniters at the launch site. Battery was brand new.

What is weirdest to me is that it actually worked once, which makes all of the other failed launches more of a mystery.
posted by 4ster at 11:31 AM on October 14, 2018

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