home made launch controller

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Dec 3, 2010
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G'day guys,

I recently made a new launch controller, in eager anticipation of firing my first clusters and AT's. The Estes Electron Beam that i got with my starter kit just won't cut it! Navajo and i got the parts at a Radio Parts (same as Radio Shack in the States). Building it was challenging but rewarding in the end.

Building the controller ourselves ended up the cheaper option after looking at commercial alternatives. It cost me aprox. $35 USD including battery. I challenge you to find a better price.

I have now ended up with a good looking controller to launch any type of rocket I like.

Here is a photo of my controller and 12v gel cel:
Smart looking controller there, Blackbird. Any chance of a photo of the 'internals'? :)

I've been meaning to get round to building a controller like that for my 12v Car Jump Starter battery. - Yet another thing on my todo list. :rolleyes:
Originally posted by cydermaster
Any chance of a photo of the 'internals'? :)

I basically dupiclicated the Estes Electron Beam controller but modded it to be a 12V launch system rather than a 6V. All the cables were solded on securely. In the picture above my finger is pushing down the safety button which activates power to the main switch. The green light flickers on once the safety button is push

I tested the controller on a digital multimeter to see whether i was getting any power through to the aligator clips. The multimeter read 12.6V (more than enough power to launch my Tres).

any way here is the pic of the internals....

Very nice job blackbird!
For 2 and 3 BP motor clusters your current upgraded system should be fine. If your planning on flying lots of clusters or 4 Bp Motors and up, you'll have a lot more consistant success if you move the battery to the pad side of the system, with the shortest micro-clip leads you can get away with between the batttery and motors. If at all possible it would be good to add a relay to your cluster launch equipement circuit. There have been several great threads on building relay ignition systems on this forum, a search should bring up plenty of info.
For all reading this thread I just last weekend purchased a new Hobbico 12V 7amp/hr gel-cel like the one blackbird pictured for $20.99 at a local hobby shop. Believe it or not that's almost 15 bucks cheaper then when I bought the exact same size/volt/amp battery in 1993!!! Something that actually went down over a decade??? wow! It wasn't like these were old stock or anything, he had a pile of them and they have a November 2003 manufacturing date and a two year warrenty to boot!:D :D
Heres the diagram I used for my Relay Launch System. 30 some years of clustering 2 to 8 BP motor's I can still count the unlite cluster motors on one hand:D
Hope this helps a little. Happy clustering!
Can any of you fellas explain to me in more detail, what exactly is a "relay launch system"?.......

.........and what does it do?? :confused:

I am going to build a second 12V controller with a different design so Navajo and i can drag race our Tres' :D
Try to picture this.

The battery is very close to the launch pad so the wires are short. This reduces any voltage loss to the rocket.

The thing that connects the battery to the rocket to launch it is a relay capable of handling the current the igniters need.

It doesn't take much power to trip a relay.

All that is needed is a very low voltage control like a simple push button that triggers the relay...That's what launches the rocket!

I can draw you a picture if you need one.

Now this is pretty simple...do not build one from this.

This is just to show you how a relay system works!

The switch at the left is the launch button with the "rocket clips" on the left.

When attempting to ignite clusters, as near simultaneous ignition of all the motors in the cluster is the key to a successful flight. By moving the battery position to the pad (as close as possible to the igniters) and using as heavy a connection wire as you can get your hands on, reduces the voltage and amprage drop to each igniter. This allows the maximum amount of current to flow into the igniters in a split second after the relay closed. In essence the hand held controllers is only a contol circuit suppling power to the Relay coil, this could be done with very low voltage bell wire. The power is provided between the relay and clip whips by the battery sitting right under the launch pad. In the photo below the box hanging under the legs of the pad is the relay box. the battery is in the black plastic box under the launcher. You can see this is a much more efficent way to provide power to the igniter than trying to push all that power the 25 to 50 feet if the battery is placed with the contorller at the launch control table.
A relay system can be used for single motors, in fact most HPR launcher placed hundreds of feet from the launch control range head are usually relay systems. anything you can launch with a estes style controller can be done with a relay, Clusters however over 2 motors really need the power provided by the relay systems.
If you look closely in the top right photo you should be able to pick out the relay and the #8 standed Copper red and blue wire used to connect the battery to the relay input contacts.
hope this helps