| I have made slight
changes to almost every one of the castings of this fuel. A little more
of one ingredient or a little less of another. It has taken a little
while, but I am beginning to get a feel for it. I have kept careful
notes as always, and they are starting to pay off.
For today's test I had a
specific purpose in mind. I wanted to pump up the color and lower the
overall brightness. I also wanted to test a 38mm C-slot geometry to
extend the burn time for better visual effect. The overall thrust time
according to the test data was 1.35 seconds. The flame was visible for
1.27 seconds as calculated from video footage.
This fuel has
proven a bit reluctant to light. In the previous two test I cast
a short section of RIO doped dextrose propellant at the forward end.
This helped to improved ignition times. I decided to skip that step
with this motor and it proved to be a mistake. It was 12 seconds
from the time the igniter fired until the thrust began. That is
the longest time I have ever recorded for ignition lag. I will resort
back to my RIO doped "pre-heater grain" in the future.
Once the motor fired, I
was rewarded with a well formed, beautifully colored flame. There was
also an interesting candle effect at the end of the burn. This is
definitely one of my favorite static test videos.
The ISP was back down in
the "normal" range on this burn. The 12 second ramp up may have been
part of it. The rest of it was probably due to the fact that the last
half of the burn was a long tail off below the 80 Newton thrust range.
It still came in at 151.48 total Newtons and 112.21 average Newtons.
ISP was 114.94
38mm C-slot
static test 2-21-07
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