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
wasnt 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
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 cant
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 doesnt 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 hadnt 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
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.
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.