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Old 09-05-2010, 10:57 AM
dcastle dcastle is offline
Intermediate Rocketeer
Join Date: Aug 2006
Posts: 30

Originally Posted by sandman
I have one of the servo launchers...someplace. It's kind of a cool idea with the pneumatic control.

Sort of like a relay system. but pneumatic.

I can easily reproduce the wooden parts. I even made some of the old Tilt-a-Pad launchers from some old redwood I found.

The only change I made was to increase the disc size to 4" from 3 3/4".

I only had a 4" hole saw.

The one in front has a 4" disc(top) and the one in back I sanded down to 3 3/4"

The bigger one looks better...and a lot less work!

I had one of the servo launchers when I was a had been my cousins and then became mine when he got out of rocketry and dropped off a bunch of great stuff.

The launcher was cool and very portable....but...I discovered a fatal flaw in the design one day.

The safety interlock key is on the pad, not on the launch controller (which is a plunger connected to a 10 foot tube that inflates a balloon that pushes the batteries against the contacts to fire the igniter). One fine afternoon in the mid 1970s, I decided to fly my Groove Tube. I set it up on the red servo launcher, hook up the igniters, put the key in then walk back to the launch button and push it...nothing happened. I noticed that the light in the safety key was out so I went and checked the clips and the igniter (which hadn't fired). I then wiggled the key and got it seated better...the light came on and then I heard a hissing sound next to my ear....the rocket was taking off not 3 inches from my head! I ducked quickly and off it went for a successful flight but a rattled flyer.

Here was the problem...when I put the plunger down on the ground to check the pad, it was slightly depressed. When I wiggled the key/light (again, on the launch pad itself), it made contact...and the balloon was, unknown to me, inflated enough to trigger a launch. It was at the ripe age of maybe 13 or so that I realized that if I ever designed a launch control system, the safety interlock key must be placed with the launch button -- not on the launch pad.

I recently picked up one of the Centuri wooden launch pads, still unassembled in the box. The one I have is LIA 77. Outstanding quality parts though the fit is very tight so I haven't worked on putting it together yet. It will also need to be stained and varnished. Not sure when I'll use it but sometime when I'm flying Centuri clones I will.
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