Dipping igniter's

Just make sure it's not teflon coated, pyrogen doesn't like to stay stuck. If I can make the May club meeting at challenger, I'll bring my pad(s) and spare wire and finally get to say hi.

Reply to
Challengeder Center
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That should read D(AWG)=.005·92^((36-AWG)/39)

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Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

This should be in the FAQ.

Reply to
Jerry Irvine

Be sure you save your scientific calculator to do the calculation.:) Not very easy to do by hand. Pick up a solar TI-36 calculator that does tons more than the SR-51 I used in college '74-78 for $18.50. The TI SR-51 went for close to $300.00 back then

Kurt Savegnago

Reply to
Kurt

Man,

This was a great thread. Thanks to all that replied. I don't want to sound like I'm kissing butt, but all the advice here has been very helpful to me. Been working on getting a batch of igniters to work and now I know why some work and some don't. Standardizing my technique with the tips gleaned here is only going to lead to success. Any advice on gauge sizes? I know 22 gauge is supposed to be used for wires for G and larger size engines. But is 26 gauge O.K. for the smaller APCP engines? Any suggestions for nichrome wire gauge sizes? Been using 30 to 34 gauge nichrome and the 34 gauge seems to work better. I've made igniters using silver solder and with just using a wire wrap tool. Any suggestions for an ohm meter as some of the standard entry level meters don't record low enough.

Kurt Savegnago

Reply to
Kurt

Well, my HP45 cost $400 ('74, I think), and I still have it. Neener, neener, neener! :^D

Reply to
bit eimer

If you get a good 3/4" to 1" length of the wire coated with pyrogen, the width of the igniter doesn't make much difference. Most people over-kill here like they do everything else. Remember how an igniter works - it lights the propellant. It doesn't launch the rocket. A good igniter will burn very hot for a second or more, even with a thin coating of pyrogen. You only have to light a tiny spot on the core, and the flame will spread. As long as the pyrogen is very close to or touching the inside of the core, it will light any sized motor (as long as the leads are long enough), but it might take 1/2 second or 1 second longer than a great big igniter because the flame front will need to spread out before the motor comes up to pressure and really gets cooking.

I use 26 gauge cat-5 style wire for my long igniters and have used them in K-M motors.

I use 30 gauge wire-wrap wire for my shorter igniters, and have used them in D-K motors. I have lit at least 20 K motors with 30 gauge igniters. They take a second or so to come up to pressure, but I think that's just fine. Kind of dramatic, in fact.

The only reason I don't use the 30 gauge wires in longer igniters, is that they are not stiff enough to push up into a motor more than about 16" long. Yet another "size matters" issue :-)

Of course, some people like to say that they got "instant ignition" and in that case a big honkin' igniter will help, because they light more of the propellant at once, and they produce some amount of pressure themselves. But, of the launches I've seen where people say they got instant ignition, they didn't really. Maybe their reflexes are just slow and they thought it was instant :-)

On your question about nichrome: get a conductive pyrogen like Firefox sells, and forget the nichrome. It's a waste of time. I can make igniters

10 times faster with conductive pyrogen followed by a high-energy pyrogen, and they've actually been more reliable, AND they take a lot less current so they work very well in clusters and airstarts.

I use the meters that harbor freight has on sale occasionally for $5. I bought 5 of them last time. They measure accurately down to about 1 ohm with .1 resolution. Most of my conductive pyrogen igniters end up in the

8.0 - 12.0 ohm range, which is measured very well with that meter.

-- David

Reply to
David

I no longer have the HP-21. Good calc.

Jerry

Reply to
Jerry Irvine

Kurt wrote: > lovs2fly wrote: >

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Reply to
David Schultz

So that is a sales pitch of sorts :)

Reply to
Jerry Irvine

Lucky Stiff,

The nicads on the 51 are gorked and not replaceable. Nice calculator for the time. You were an expert in reverse Polish notation I see. :)

Kurt

Reply to
Kurt

My nicads are also toast and I've never (yet) tried to replace them. Just have to run off the adapter.

IMHO, RPN is *still* the only way real men compute!

Reply to
bit eimer

"bit eimer" wrote in news:25yde.3526$D91.2638@fed1read01:

The nicads on both should be replacable. You may have to crack the case to get at them if they're not part of a pack that pops out. If they've died and you are running off of a charger, you should remove the batteries because they will eventually leak. This brings back memories for me too; I worked at the Abilene TI plant back in the early 80's - calculators, Speak-and-Spell, TI99/4A stuff. BTW, I've got two TI59s with print cradles ans related stuff going up on ebay tonight.

Reply to
Dan Major

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