What do you mean by duds? They didn't ignite, or something happened in flight?
If they didn't ignite, 99 times out of 100 it's because the igniter was inserted incorrectly, or the clips to the controller were too far apart/shorted, or the battery was low, etc.
I did a launch with a bunch of kids a couple of weeks ago. Out of > 500 engines, we had a couple of dozen fail to ignite. In EVERY CASE, it was either inserting or connecting the igniter incorrectly, and re-using the engine with a new (properly installed and connected) igniter made it work just fine.
Hard to say what might be the motor problem from just this info. I assume these are Estes black powder motors. Most failures are external electrical issues, not motor problems.
What do the igniters look like after a launch attempt on a "dud" motor? Are they burned/melted in half? Are they melted at some point OTHER than in the middle? Do they show any indication of being heated at all? Many ignition failures are caused by shorts in the igniters and/or clips outside of the motor or the igniters are not inserted all the way into the motor and up against the propellant grain. Its easy to short the igniter wires together if the plastic nozzle plug holding the igniter in is not inserted properly. Make sure the silver colored igniter leads do not touch each other. Also make sure the igniter leads and launch clips do not touch the metal blast deflector, or other metal parts, and cause a short across the launcher leads.
Test fire an igniter outside of a motor and ensure you get a prompt ignition of the igniter and pyrogen (the black stuff on the igniter). If the igniter does not fire almost instantly, replace the launcher batteries.
Peer down into the nozzle end of a "dud" motor with a flashlight. You should see dark black propellant. Sometimes light gray nozzle clay will be coating the propellant and preventing ignition.
A 33% failure rate is NOT typical of commercial BP motors.
I think what we're seeing right now is that there are issues affecting the hobby on a regional basis. For you folks in the "Great White North", it's a lack of AT motors. In the states, some areas have been hit hard by the ATF regs (or vendors' interpretations of them), inability to get local storage, etc. Meanwhile, in regions where local vendors and a good motor supply are available, the hobby has been growing by leaps and bounds.
I think you're right Ray and I was only speaking about the U.S. At least in the South, I think there is still some growth at least on lpr, which is where most of us got our start.
What kind of motors are you using...and just for the record...out of the well over 1000 rocket launches I've made in my lifetime, I don't recall ever having a motor fail to operate. I've had a few where I had to use more than one igniter, but that's usually because you did not install the igniter properly, or IT was defective.
I did have ONE rocket engine that for some reason had a "blow out" in the side of the motor which burned through the wall of the motor and through the body of my rocket as well, but I didn't know it until the rocket landed. I knew that it sure didn't fly very straight, but didn't know why until I examined it. But honestly, I don't think I've ever had a motor to fail.
And I was walking down the street one day Being pushed and shoved by people trying to beat the clock, oh, so I just don't know, I just don't know And I said, yes I said .....
9:47 am 28/04/04 ( note you daft yanks the CORRECT Date formatt not that silly backward one you guys use....bah putting the month before the day....I suppose you put carts in front of horses as well)
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