January 26, 2003 Meeting Notes

 

Small Vehicle Work

 

We had a bit of a scare Tuesday, when we notices that the ½” thick engine bulkhead had been warped quite severely by the welding on of the trunk release mounting plates.  We tried pressing it back into shape, but it kept springing back.  The prospect of rebuilding it from scratch wasn’t very pleasant, but we finally managed to get it back into shape by welding beads on the opposite side of the bulkhead until it pulled back flat.  Surprisingly, it now seems as good as new.  We are going to be more careful with welding on accurately fitted components in the future.

 

The cable routing for all the engines was completed: http://media.armadilloaerospace.com/2003_01_25/cables.jpg

Each white cable is a 5 conductor Tefzel cable, four for the main engines, one for the master cutoff, a couple extra for the ejection and release actuators, and one shielded cable for the video camera in the base.  We still have to do a lot of wiring to get everything together, and Russ needs to clean up the quad motor drive for testing.

 

We are still waiting on our last order of silver screens to show up, and a new set of nozzles for the engines with a smaller throat.  The current 2” throat nozzles probably can’t be throttled down enough to hover test the 250 lb vehicle without the chamber pressure going sub-critical, so we are having DynaTurn make a set of 1.25” throat nozzles for us.  This will also be a nice thing for engine testing, because we will be able to swap out two different throat sizes with identical catalyst packs.

 

Because this vehicle doesn’t have landing gear, we are going to do the hover test with the vehicle suspended under a crane.  If deliveries cooperate, we should be doing that weekend after next.

 

Ky Michaelson at http://www.the-rocketman.com is making a custom 4’ diameter nomex drogue for us.  This, and the cold-gas drogue ejection system are gating items for a high altitude flight, but we would also like to get some new electronics done before flight as well.

 

 

Big Vehicle Work

 

We have used a couple pads of memory foam (Tempur Foam) in the manned lander, and we have been considering using that for a universal seat in the big vehicle, as opposed to custom hard-foamed seats.  The pads from AircraftSpruce were fairly expensive, but it turns out that you can get the same material very inexpensively as mattress pads.

 

We added two honeycomb panels around the pilot, which will also serve as mounting points for most of the electronic gear.  It took more weight in foam than I would have liked to fill everything in, but it seems comfortable.  The memory foam is many times as dense as the two-part expanding foam we made the rigid seats out of.

 

In preparation for full scale drop tests, Russ did a full seam weld on the insides of all the cone panels, which we hadn’t asked the fabricator to do.  We finished getting all the bolt holes through the boilerplate tank end to hold the ballast for drop tests.  Drilling 24 of 3/8” holes through the tank dome was a lot of work, but it got easier once we started making pilot holes first.

 

We finished the spec for the hatch reinforcement and sealing arrangement, and for the full size crush cones.  The full size cones will be capped with aluminum hemispheres from: http://www.jgbraun.com/balls.html

 

An 800 gallon fiberglass tank has been ordered.  This tank is the same weight as our proposed carbon fiber X-Prize tank, but half the volume.  We will be able to fly the vehicle with this tank for early testing, saving the carbon tank for when the bugs are worked out.

 

We are probably a month out from full scale drop tests.

 

 

Amateur TV

 

We tested a bunch of products from www.hamtv.com on Saturday, and I think they will serve us well.  A 20W transmitter will get us live video and voice well past the 100km mark, and the quad-view multiplexer will allow us to get multiple views at the same time.

 

We are using “lipstick cameras”, which are compact, rugged cameras commonly used in race cars and other rough environments.  We will probably only fly one in the 2’ vehicle (stuck in one of the legs on the bottom), but we plan to have four inputs on the X-Prize vehicle:  tail, nose, pilot, and rear equipment view (so we can watch the parachutes and such).

 

I will have the flight computer add the current GPS data and parachute actuator state to the video signal with the character overlay card.