August 14, 2001 Meeting Notes
Phil and I picked up another four gallons of peroxide from
Rinchem today. We are going to have to start
filling two jugs at a time, now that we are firing the bigger motors more
often, because we used half of it just tonight. We will probably wind up taking an entire drum out to the test
range and storing it in a shed when we move big firing operations out there.
Russ finished all the lathe work on the main engine, so it
just needs a bunch of drilling and tapping on the flanges. With full flow, this should produce well in
excess of 600 pounds thrust. We will
probably fire it at Long Range briefly with a small solenoid and plumbing that
will prevent it from making more than 150 pounds or so, and do some full flow
water tests to check the spreading sheet and retaining plate retention before
firing it full on out at the range.
I have changed our test stand electronics over to new
equipment that we will be able to run strictly from DC power, but the dataq
DI-195B that I am using is responding slightly differently than the DI-151RS
that I had been using before, giving me jumpy data. I know it is a software issue, because when I use their bundled
software, it is steady. We can still
use it for basic measurements, but not smoothness tests until I fix this. Worst case, I can use their active-X
control, but I hope to figure out the raw serial line protocol properly.
The electronics box is now converted over to a single large
connector for all the attitude engines, so we can never again plug two of them
in backwards. We converted both the
small and large landers to the new plug type, and mounted a new four engine
manual control box on the fill cart that can directly replace the electronics
box. This is a big improvement in
several convenient ways.
We made several improvements to the fill cart today. We increased the tank hose from 4 to 6,
which reduced the vacuum loading time for a liter of peroxide from 60 seconds
to 37 seconds. We put on a bigger vacuum
pump that Phil rigged up a set of check valves for, and it works significantly
faster. We added a check valve in front
of the nitrogen solenoid so we can change nitrogen tanks in the middle of a
pressurization if necessary, and we increase the size of the nitrogen line and
solenoid to make pressurization faster.
We are going to put in an application for an FAA waiver at
our test range soon. We will just go
out and fly some HPR vehicles the first time, getting us used to the launch and
recovery process there before putting up one of our peroxide vehicles.
We weighed several components today:
The electronics box, which is exactly the same on both
vehicles, weighs 13.2 pounds.
The big vehicle in short form weighs 120 pounds without the electronics
box or propellant.
The small vehicle weighs 29 pounds without the electronics
So, in minimal fueled (one liter / four liters) hop form,
the small vehicle weighs 45 pounds and the big one weighs 148 pounds. The engines are almost exactly the same in
relative thrust we didnt test the small ones after drilling out the nozzles,
but they should be around 20 pounds, and the big engines should be slightly
less than the 65 pounds we see on the test stand due to longer hoses.
The big lifting engine weighs 16 pounds, and there will
probably be another 14 pounds of valves, joysticks, and manifolds before the
manned vehicle is completed, giving a minimum weight of 165 pounds + pilot +
propellant. We can reasonably load
about fifty pounds of propellant, so we would be looking at a total liftoff
weight of up to 400 pounds. The extra
outrigging and braces for the long form of the vehicle adds another fifty
pounds or so of metal. Depending on the
propellant load and pilot weight, it should be able to fly for ten to fifteen
In HPR terms, our central engine and tank make an O-3000
motor (around 25,000 NS of thrust)
Big Frame Hops
We sort of broke best scientific protocol and added more
catalyst to each engine today without retesting. We still suspect that our cloudy runs on Saturday were at least
partially due to the 100+% humidity and cooler temperatures, but we just went
ahead and filled the engines without retesting. We now have 21 discs in each engine, compressed very slightly,
with no spacer at the bottom. All the
exhausts were clear today.
We loaded up four liters of peroxide, which should give
around five seconds of flight on the big vehicle. We pressurized to a little over 500 psi, which took over half of
our new, larger nitrogen tank. We need
to move up to the largest size nitrogen bottles we can get.
The first test was with a 20 hz pulse rate, instead of the
30 hz rate we usually use on the
We didnt have a cameraman today, so the video isnt all
that good, with the lander getting almost out of the frame:
It had an obvious tilt towards the offset CG due to the
electronics box (which will be worse when the pilot is there), and it was very
jerky. A first look at the telemetry
graphs showed that it was rapidly making large overcorrecting rate
We made another hop with the pulse rate set to 30 hz (we
just barely were able to lift off with the 380 psi we could get in the tank),
but it was significantly worse, and it tipped over almost immediately.
I still have a lot of analysis to do on the data, but there
are clear differences in the behavior of the big and small vehicles. The big one probably has quite a bit more
control authority, because the small one has mass (the landing pads) much
farther away from the centerline. The
valves and plumbing are also different enough that the relative pulse behavior
may be different.
We will try again on Saturday with software changes.