| This was the seventh
documented test using –325 mesh iron as an additive in my quest to
achieve a flame on par with the flame present in composite fuels. The
first five test using 5% iron in a Sorbitol based fuel (while
successful in creating a flame) did not meet the goal in terms of flame
size and color. Test six utilized 10% iron in a Sorbitol based fuel and
was successful in achieving both the flame size and color goals. The
results of that test are posted on the Sorbitol
Flame web page.
For this test I decided to use dextrose as my base fuel because it is a
readily available fuel, easy to work with, more cost effective than
Sorbitol and has been highly documented with other experimentalist.
When burn testing at 1 atm the burn rate was noted as 11 seconds per
inch. This is more than 20% slower than the Sorbitol based fuel. I
suspect the dextrose will require a longer heating time after melting
to remove residual moisture. Also noted (after the test strand was
burned) was a fair amount of residue left in the shape of the test
strand itself. It appeared to be unburned iron. Again I suspect the
residual moisture was the cause of this.
The grains were allowed to cure for 6 days before firing. The motor
took a little longer to come up to pressure than usual and that is
thought to be caused by the use of a new type of igniter. The total
burn time was slightly longer than with Sorbitol, but when the delay
lag is taken into consideration the times are within .05 seconds of one
another. This was a bit of a surprise because I expected the dextrose
to have a faster burn time than the Sorbitol. Again I suspect moisture
in the fuel. About 6 grams of residue were present when the motor was
taken apart for cleaning. This was not the case with the Sorbitol based
fuel. More testing will have to be done.
Overall I was very happy with this test and the flame was somewhat
longer and more defined than with the Sorbitol based fuel. The ISP was
right on track with what I have grown to expect with this formula and
my method of preparation.
For a better look at this fuel check out this static test.
Again I hope you find this information useful in
your rocket endeavors.
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