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Tweener
08-22-2005, 05:10 PM
I've been absent posting to the forum for a bit (though I've been lurking a while). I haven't had anything wothwhile to post. But now I have a couple of questions. I'm planning on trying the Aerotech E15 or E30 24mm x 2.75" with an Estes Big Daddy, and would like to know what RockSim says (Craig?) about the 4 and 7 second second delay ejection velocities (my trial ran out). Also, I intend to build my own 12v launch controller and would like to know what current rating should be used for a push button switch to be sure I don't weld the contacts together if I use an auto battery for power. I plan to use an LED and resistor for continuity, so there should be just a few milliamps current before the "short".

CPMcGraw
08-22-2005, 08:37 PM
...now I have a couple of questions. I'm planning on trying the Aerotech E15 or E30 24mm x 2.75" with an Estes Big Daddy, and would like to know what RockSim says (Craig?) about the 4 and 7 second second delay ejection velocities (my trial ran out).

Absolutely go with the E30-7. Dv = 21 fps. The 4 second delay is still travelling upward at a very high rate of climb. Dv = 79 fps.

Stay away from the E15, the Dv is way too high for any of them...

The attached RKT file is as close to the kit as I could get, because I didn't know the actual dimensions and weights of the kit components...

Also, I intend to build my own 12v launch controller and would like to know what current rating should be used for a push button switch to be sure I don't weld the contacts together if I use an auto battery for power. I plan to use an LED and resistor for continuity, so there should be just a few milliamps current before the "short".

Jameco...

Big Red Pushbutton, SPST, momentary contact, 125V, 3A, part #315432CJ...
Key safety switch, SPST, round, 125V, 6A, part #105831...
LED, Red, Ultra-Bright, 20mA, part #152805CJ...

Personally, unless you're planning on "flashbulb" ignitors, I'd stick with the tried-n-true 12V lamp. Keep the circuit simple and it'll work every time...

Incandescent Lamp, 5/8" hole, 12V solder terminals, part #215714CJ...

Enclosure, ABS, 7.5" x 4.3" x 2.3", part #18905CJ...

This is essentially the same controller I built 20 years ago, and if I felt like cleaning it up, it would probably work fine today. I like the umph that a 12 volt car battery supplies to kick the pig off the pad...