#11
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The Astron igniter was just a piece of nichrome wire with a bit of coating that insulated it from shorting against itself so it would get hot at the point of contact to the propellant. It may have helped ignition a little too, but bare nichrome ignites BP just fine without it. Solar igniters have two heavy wires with a tiny nichrome wire bridging them together. The black pyrogen also acts to keep the bridge from breaking apart. |
#12
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Cool. So were the solar ones supposed to be more reliable? And why were both sold for a time? Simply to let the old stock run out? -Tim |
#13
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Ah, but it wasn't *just* a piece of nichrome wire: http://www.google.com/patents?vid=U...AJ&dq=3,363,559 There was more to it. |
#14
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Oooh....resistance fuse wire! Maybe I should have said, just a patented piece of nichrome. |
#15
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Both were sold at the same time for a while. Astron igniters were cheaper and I remember buying some because of that. Astron igniters came with motors when I was a kid so I never didn't get Solars until the Astrons were gone and they started packing them with motors. The Solar igniters were more reliable for most people because the pyrogen helped ignite the motor even if it wasn't against the BP grain. The Astron nichrome wire igniter had to be against the BP to get reliable ignition. If you were very good at positioning the Astron ignitors, they were more reliable because there was no thin hidden nichrome bridge to break. The biggest benefit of the Solar igniters was that they could be fired with 4 AA batteries (6v). The Astrons needed a 12v source to get hot enough because the wire was thicker than the bridged portion of the Solar. |
#16
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I got into the hobby around 1982, and the solar igniters were packaged with the engines, but the Astron ones were still available. As I recall, the Astron were actually slightly higher around that time, but I'm too lazy to go look it up in the catalog archive right now
-Tim |
#17
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I went back and looked. The few catalogs I checked, both were listed at the same price. |
#18
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In defense of the Astron ignitors, I suspect user compromises were much of the problem. The spec called for "photo flash" batteries (IIRC) which have lower output resistance and thus can dump more current. But users tended to stick four of any-old D cells in the Electro Launch, and these just weren't up to the task. As I recall, we upgraded our Electro Launch to 12V (8 D cells) but whenever we were getting ready to launch, we found that resulted in having 8 dead batteries to replace instead of four. Our next upgrade was to the Electro Launch variant that used the car battery. With that unit, all the uncertainties went away I agree that the Solar ignitors are not as rugged as the old ones, but if handled properly, are more reliable when you punch the button. I've lit clusters of 9 motors twice using them with no problems. Where I run into handling problems is with the deep core motors such as the A10. Since the leads flare apart, on the deep cores, the leads are forced together and can short. The user needs to reshape the leads to prevent shorting and that can result in breaking the pyrogen and damaging the bridge wire. (Just to be clear, broken pyrogen is OK as long as the bridge is still intact.) Doug |
#19
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Well, I did a little research myself. Here's a mini-history of the Solar Igniter! (Dates based on catalogs in the Ninfinger archive):
1974: Solar igniter makes it's debut, as a companion to the venerable Solar launch controller. Pricing is the same as for Astron igniters. 1985: Oddly, this year, Solar igniters are priced at $1.40, whereas Astron are $1.50. This is the only year that I could find that the price differed. 1986: The price is back to the same again, $1.50 for each. 1987: Astron igniters disappear from the catalog. 1988: "Solar" designation dropped This was a learning experience for me -- first of all, I was surprised that the Solar igniters/controller dated back to '74, I was under the impression it was relatively new when I got into the hobby around 1982. It's also odd that they marketed both of them for 13 years, so I"m guessing it wasn't simply a matter of letting stock run down... As an aside, anyone remember the Power Pulse launcher? When it came out I was a little jealous that I had the now "second-rate" Solar controller. But looking back, that Power Pulse thing was just odd. Can one even get those weird Polaroid batteries anymore? As another aside, looking back in those old catalogs at the pricing is REALLY depressing... 39 cents for a pack of igniters that I just paid $5 for a few weeks ago... -Tim Last edited by tfischer : 10-04-2007 at 11:34 AM. |
#20
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You must have missed this one, Tim: Name "Solar" dropped from packaging in 1988. Upper left of catalog page. BTW, the 88, 89, and 90 catalogs are posted on Ninfinger. 1988 Catalog 1989 Catalog 1990 Catalog
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