May 1, 2001 Meeting Notes
In attendance (the whole crew!):
8 each of all NPT to 3, -4, and 6 male/male adapters in aluminum
Two stainless steel quick connects with five plugs
20 pounds of stainless steel pipe fittings (four of every
combination of 1/8, ¼, and ½, plus Ts and 90s)
-6 aluminum speed flex hose ends
Stainless ¼ needle valve
Mil-spec aircraft electrical supplies
Pilot headsets for piloted VTVL
Extra burst discs
Full complement of AN fittings in aluminum to replace some
of the steel ones
150 psi tank
Various 150 psi plastic fittings and hose
150 psi solenoids
More big solenoids
Tank pressure transducer
Tank temperature transducer
Russ: Fill both nitrogen bottles
Russ: Fill welder argon bottle
Russ: Foam blocks for VTVL from your local foam supplier
Phil: Charge all the batteries
Phil: Pick up more tables
Phil: 70% food grade peroxide
Neil: 6 of hard line for pressure transducer. One side female ¼ NPT, the other side
ideally male 1/8 NPT, but we can adapt
Neil: 1000+ psi nitrogen regulator
I spent three days at Space Access 01 last week, and gave
the first public presentation of our work.
Jess Sponable, who was the director of the DC-X program, gave our
direction his seal of approval after my talk.
An interesting bit was that XCORs 15 pound biprop thruster,
which was fired at the hotel, was far louder than I expected. It was at least twice as loud as all four of
our 15 pound engines running together on the VTVL, which fits with noise
scaling by the third power of exhaust velocity.
We got a quote for burst discs to our specification from www.bsbsafetysystems.com -- $338 each! Phil is talking to another company about getting something
reasonably close that is in mass production.
This company sells fiber optic gyro demonstrator kits
(single axis) in two different quality grades for $1500 and $2500:
I may wind up getting a couple of these when we want to do
high G launches.
We rebuilt everything in our plumbing system with all
stainless steel fittings and aluminum hose ends. After the cook-off last week, we arent going to use any brass or
non-stainless steel anywhere in the system, even if it shouldnt have peroxide
sitting on it. We have two bits left: the
bottle valve adapter is plated steel, and the vacuum hose barb is brass. We should probably just move to a custom
machined aluminum four port bottle manifold for the test stand like we have on
the VTVL, except with bigger ports (1/4
Russ and Phil welded a stand on the fill cart for the
solenoid control and screwed the solenoids to the mounting bracket. It is amazing how much this cleaned up the
cart. There are still a few things to
add to the fill cart:
Checklist mounted next to the control box.
Cradle for nitrogen tank.
Something to secure the water jug hose holder.
We water tested a couple times to get the new plumbing leak
We finally ran Juan Lozanos engine. It was designed as a 100lb thrust engine,
but we werent expecting to be able to flow enough peroxide through our current
solenoid to see that much thrust.
We used 425 ml of 98% + 75 ml of distilled water in each
We ran it once at 450 psi, and again at around 410 (our
nitrogen bottle was running out). It
made a bit over 50 pounds of thrust. We
considered plumbing up our big manual ball valve to the engine so we could give
it full peroxide flow, but we couldnt think of a safe and sure enough way to
actuate it, so we sensibly put it off.
We will probably try two ganged solenoids next week.
His catalyst pack seems to work fine, with a very short warm
up time. I am going to inquire about
getting one of his new packs that is supposed to survive with 98% peroxide for
We ran into a few issues during the testing:
Our bottle pressure gauge was killed by the cook-off last
week. The one on the VTVL still works,
but Ill pick up another one.
The new stainless steel quick connect we installed couldnt
be popped off when at the full 450 psi pressure, although it could at 200 psi.. We just left the fill cart connected to the
test stand during the firings, but we need to be able to remove it for the
VTVL. The old steel ones we used had a
lever on them, so they popped right off.
We may try welding some bars to the connector, but I will look for more
The solenoid driving battery ran out just as we were about
to test. I had done a couple water runs
and dry runs, but when I fired the engine for real, nothing happened. We hooked another battery up, but that did
involve approaching the test stand. In
the future, we should have a long coil of wire from the solenoid going around
the corner to the actuation electronics, instead of having them out by the test
We hashed out the redesign of the VTVL tonight. Bob is going to tack it together this week,
and we will check it out on Saturday.
We are going to investigate duplicating the VTVL with 150
psi components. The Isp will suffer due
to very small expansion ratios, and the engines will need to have bigger
throats, but all the plumbing can be done in plastic, avoiding corrosion entirely.
A list of peroxide / material reactions is available at:
Notably, nylon and Delrin have severe effects, which
precludes several classes of fittings and hose.
We are also going to look at the other extreme running the
current tanks at 1000 psi.