August 24, 2003 notes
All engine plumbing and wiring is complete on the big
vehicle. We loaded water into the big
tank and tested all the valves, with pretty good results. Our distribution manifold has a leak in the
weld which will need to be fixed, and the fill port 2 threads were loosened
during the filling process when the giant hose pressurized itself and whipped
around a bit. We cant just weld the
inlet fittings, because the check valve is stainless steel, while the rest of
the hardware is aluminum, so we may need to weld flanges onto each side and
bolt them together.
If there was catalyst in the
engines, the big vehicle is now capable of flight, but we still need to get the
drogue cannon worked out before it can land properly. We also need to make some honeycomb panels to protect the base of
the tank from exhaust at launch, but we are running out of things to do on
it. The base will need a fair amount of
rework when we put the full size engines on it, but the basic layout will
probably remain the same.
We made a special aluminum plate to allow us to tack weld
future engine retaining rings in place while under pressure. Welding the anti-channel rings in is very
good for several reasons, but previously it has given us somewhat variable
compression, so we had been planning to make a tool to fix this.
We also did some work with the high power video transmitter
for the high altitude flights. We
mounted the video overlay character generator inside the transmitter box and
permanently spliced it into the video stream, which worked out nicely. This 20 watt transmitter should give us a
signal all the way to 100km, and the overlay board will allow the main computer
to display primary data (GPS position and event sequencing) past the point
where the 1 watt 802.11b system fails.
Space suit pressurization
The suit outlet port was fairly easy to remove (the regulator
was missing from it anyway), so I made a two part adapter that clamped in and
gave us an AN fitting to work with.
The normal suit inlet port is not so easy to pull out,
because it is bonded directly to the suit liner. If anyone knows where to get fittings to match up with this (on a
Sokol-KV-2 suit), I would appreciate a pointer:
One of the zippers on the suit gave us a lot of trouble, and
it appeared to be a different style than all the other ones. We eventually got it closed, but the suit
leaked too much to even blow up. We
patched several holes in the internal liner, and eventually got it pressurized
up enough to hold its shape, but it was still leaking a lot past the
zippers. Russ got inside it, and it
held pressure better with him pushing the liner against the zipper. We put 2 psi in it with him inside, and got
some sense of the difficulties of moving in a pressurized suit.
We finally figured out that the internal liner actually
needs to be folded up and tied off after getting the person in it to keep it
air tight. After doing this, we tracked
down and patched a couple more leaks in the liner, and we were able to get the
pressure rising fairly rapidly. There
is a squealing leak at one of the suit glove bearing joints at some rotations,
and one of the other connection ports leaks, but the suit would hold several
psi pressure with 2scfm of air flow.
We increased the pressure some more, and at 0.3 bar / 4.2
psi, still below the normal operating pressure of the suit, the bad zipper
failed, ripping the entire length down, and making a very loud pop that was
rather, err, exciting, to those of us listening closely for leaks (Russ was not
in the suit
). Upon closer examination,
the zipper that failed was only hand stitched in with a single seam, while the
other zippers all have triple seams of close spaced stitches. It is likely that the replacement zipper was
sewn in after the suit was discarded by the Russian space program to make it
more saleable on the novelty / collector market, with no concern for its
functionality. We are going to have a
new replacement heavy-duty zipper sewn in.