Dec 19, 2000 meeting notes
Dec 19 meeting notes:
Location: Norwood Autocraft
Next meeting delayed until next Thursday due to the holidays. If we have
peroxide, it will be at Long Range, otherwise it will be at Norwoods. We
missed the last two weeks due to an ice storm and various holiday issues.
Our peroxide status is getting troublesome. We ordered 10 liters of 90%
from X-L Space Systems on November 6th,
and were eventually given a ship date of Dec 15. Dec 15 came and went, so
I left an inquiry with X-L. I got an email today saying that they had
decided to concentrate on 98% and would be refunding my money. I have
asked that we just be sent 98%, but I dont have confirmation yet.
We can dilute 98% ourselves, but if X-L doesnt work out as a supplier we are
back to meeting all of FMCs requirements or distilling and purifying
ourselves. I am still looking for a permanent building for us that could
satisfy FMC, but I havent found anything of a reasonable size for us yet.
I am all incorporated now for our rocketry work Armadillo Aerospace is a
The remaining load cells came in, so we now have 100lb, 500lb, and 3000lb load
cells. We need to wire up some connectors for these, because they are
designed to have the leads screw directly onto the meter.
The extra fittings came in.
I got enough hi-temp spray paint for the test stand.
I got a selection of vinyl and polyethylene tubing for us to use, because we
always seem to need another piece or two. Russ: I think we need some more
dual line stoppers and bottles for vacuum catch / peroxide transfer.
Neil is building the dumb rocket. We should be able to launch it on a HPR
motor at Shoot For The Stars @ Windom in three weeks.
Phil / Neil: Pick out the launch equipment we want so I can get it ordered.
I want to err on the side of an extra long and stiff rail, since we may be a bit
light on thrust to weight.
Phil: We need to get the MacGreggor information to the insurance agency for our
private peroxide launches, and we need to finish the FAA waiver.
I have done a lot of telemetry tests recently. The information is
summarized at media.armadilloaerospace.com/misc/telemetry.htm.
The final radio modem came in, so I can now set up a full duplex raw telemetry
connection, although I need to buy another full duplex dual band radio.
Phil is going to build me a PC board to replace my hand wired DB9 to dual DB25
full duplex adapter.
I have built up a pretty nice software framework four journaling and sequencing
multiple data sources that is good for both flight computers and ground
stations, and I am integrating my GPS visualization app into a general ground
station app. I am probably going to buy a PC104 development system for the
flight computer, but I am still a bit tempted to try using a WinCE palmtop with
either a USB or PC Card four-port serial adapter.
Darin is getting data from the accelerometer through a basic stamp now. We
should pick up one of the 3-axis units soon.
Darin is getting a list of the dimensions that his friend at the laser drilling
shop can produce. I picked up some 1oz silver coins that we might turn
down and use as injector plates. If we can get a lot of truly fine
perforations, there is a possibility of replacing the catalyst pack with several
When we get the next batch of foam plated, we need to get the exact process
specs that the plating shop uses.
The magnetometer is still supposed to be here Real Soon Now.
I recently did some thinking about other attitude options, and I actually think
that we could get away with using an inclinometer for pitch and roll control.
Our platform cant generate any side thrust, and wont be doing any rapid
angle changes, so I think an electrolyte-based inclinometer might be workable.
We might be able to just strap a sidewinder freestyle joystick on it
Russ / Phil: lets lay out some flight battery options next time, and see how
quickly running the solenoids draws them down.
We picked up a couple big fuel injectors from Bob today. The largest
injectors you can get are only 170 lb/hr, and only operate up to around 200psi,
which is only about 5 lb of monopropellant thrust. That isnt going to
be enough for even our small VTVL engines, but they could be useful for
dedicated attitude control thrusters on other vehicles. The integrated
solenoid and good spray atomization would be nice benefits.
Interestingly, it turns out that we are going to be able to do yaw control as
well as pitch and roll with only four engines. Arrange the engines
slightly canted so that the north engine points slightly west, the south engine
points slightly east, the east engine points slightly south, and the west engine
points slightly north. If there is equal thrust on all engines, no yaw
acceleration is produced. If the north and south engines are throttled
down, there will be a counter clockwise torque. If the east and west
engines are throttled down, there will be a clockwise torque.
There is a cross coupling between yaw and roll or pitch, where pitching or
rolling will also induce a yaw, but it can, at least in theory, be canceled out
automatically. I will modify the simulator to experiment with this and
determine what degree of cant is needed.
We finalized the VTVL platform structure tonight, and Bob is ordering the
necessary tubing to build it. It isnt going to look all very elegant,
but it should give the bottle and engines good protection and not weigh much.
We probably have another month of structure, electronics, and coding work to do,
but we are already pinched a bit by the lack of peroxide, and we are going to be
hard gated on it if we dont get something worked out soon.