Model Forum / General / Rockets / January 2007

With only having to do a little soldering I modified my standard Estes
launch controller to hook up to a 12v deep cycle marine battery for black
powder and small APCP clusters but I imagine most any type of battery
putting out 6 to 12 volts would work. I also extended the section of cord
that hooks up to the igniter to about 35'. I didn't have any interest in
standing only 15' away from a 3 banger "D" or "E" motor cluster.

See this website for wiring details on how to modify the launcher:
http://www.rocketinabox.com/launcher.htm I didn't do mine exactly this way
but it will get you in the ball park.

When I did my first cluster rockets I built the Deuces Wild, Tres and
Richter Recker kits that Fliskits offers (www.fliskits.com). Thrustline
Aerospace (http://www.thrustaero.com/) offers a really nice cluster rocket
called the Mike IX that was a good build and flys great.

Andrew Grippo

I happened to have an 8 cell 1700 mAH pack and the appropriate charger for
an electric glider.  I used that to successfully fire three Estes ignitors
nearly instantaneously.  That would be a nominal 9.6v, but fully charged
will be more like 11-12v.  It even fired one half of a Deuces Wild cluster
when one of the ignitors was shorted.

8 D sized dry cells will be a nominal 12v, but may be expensive in the long
run.  12 volt "gel cells" or motorcycle batteries are the preferred size as
they provide the voltage and similar current dump of car batteries in
compact 5 or 10 pound package.  I think gel cells can even be charged with a
car battery charger, but I do not own a gel cell and have never read the
safe charging recommendations.  Maybe someone else can chime in here.

My homemade ignition system has 30 feet of vacuum cleaner cord to run to the
pads.  It should be rated for 20 A at 110V.  For modrocks I usually don't
put the pad 30 feet away, but always go at least 10 to 15.  I stretch it all
the way out for clusters and composite D, E, and F motors.  I also used an
automotive relay to keep a relatively small launch push button and to
maintain a "larger pipe" to the ignitors for more current availability.  I
got really carried away and was able to light the continuity light with just
20 to 30 MICRO amps through the ignitors (470K ohm resistor and a transistor
to drive the LED).  I think this is overkill, and maybe even slightly
misleading as any contact (like me holding a clip in either hand) will show
continuity.  It is definitely safe for low current igniters or e-matches.

Make sure all of you components in the firing circuit are rated to 20A or
more.  There is always a possibility of clip to clip short and you're
ignition system having to handle a lot more amperage than even a 1 or 2 ohm
ignitor will draw.

Ironicly, I rarely use it as most of the time I go to larger organized
launches.

Remember that the codes are there for all launches, not just group ones.
The point is that you are safe, your surroundings are safe,  and the hobby
is safe.  You can probably argue about the motor certifications, but the
distance codes and launch field sizes are there for safety reasons and
should always be followed.

I have a homemade controller that I've been using completely successfully
for years.  For the longest time, I had a single 7.2V 1700MAh
R/C battery pack in it, and it never failed to fire 3 motor clusters.  I set
it up with launch key and continuity circuit.  I installed it in an
enclosure from RatShack, and installed a 120V outlet on the front so I could
use regular extension cords out to the pad, with a single or 3 motor clip
set that plugged in to that.

I recently added a second 7.2V pack to the controller.  Not because it
needed it, but because 7.2V packs were on clearance at WallyWorld for 10
bucks, and it was too cheap to pass up!  This setup will light anything I'd
ever need to, and it beats trying to lug a car battery.

Joe Michel

You guy's are great. Thanks for the ideas, I'm reading them all
and noting the links. All info is welcome.
John