March 14, 2004 notes:
Still not there
A short report this time, because I have a cold, and we
still haven’t gotten perfect success with the spark ignition.
We switched to the MSD-10pro ignition system, which has a
nearly 5x hotter spark, but that doesn’t seem to effect anything.
We have the data acquisition system set up so we can monitor
two temperatures and two pressures simultaneously, but we have been focusing on
open catalyst ignition tests lately.
We tried some longer reach spark plugs, with no real
benefit.
We tried sparking directly to the perforated support plate
instead of the spark plug ground by welding an extension to the spark plug
center electrode and cutting off the ground.
No real benefit.
We can get fairly reliable startup on the engine with just a
heavy perf plate as a flameholder (which should get rid of the high thrust
instability and bad thermal distribution we had with the angled flameholders),
but we almost never get it to restart on a second try when the engine is hot or
damp. “Fairly reliable” is ok on the
test stand, but it isn’t good enough when we need to start four engines on the
vehicle at the same time.
We will try more things next week.
In other news, our big order of ring catalyst arrived, so we
now have enough of that to probably see us through the year. We had some 12” diameter plates water jet
cut for supporting the catalyst in our next big engine, replacing the
plasma-cut circle of perforated metal backed up with reinforcement bars. This will save a bit of weight and make
engine assembly faster. We are now using
a carbide grid band saw blade to dry cut our engines apart. It takes about an hour and a half, but it
makes a clean cut without needing any cutting oil.
Matt is back, so we have pictures this week:
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_a.jpg
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_b.jpg
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_c.jpg
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_d.jpg
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_e.jpg
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_f.jpg
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_g.jpg
http://media.armadilloaerospace.com/2004_03_14/2004_03_13_h.jpg
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