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Lift off Dart
Rocket
These are
photographs taken of the first launches of the Dart
rocket.
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What a first launch. Having
worked it through on the simulator, I decided to
run the first launch at 100psi. On the left, the
dart is sitting on the top of the connector which
just slots into place in the cut top of the
bottle which is taped to the pressure vessel
(tested to 140psi full of water). You can see the
nose is a nice shape and you can just make out
the fins. The dart simply rests on the connector. Taking
into account the fact that the fields were
deserted, I decided that as I was the only human
the dart could hit, I would be safer if I was to
aim it away from where I was standing so I put
around a 10 degree from vertical angle on it
which would make it miss me by at least 50 yards.
So, I pumped it up, got the camera out and,
while looking at the launcher through the
viewfinder and standing at a safe distance, I
pulled the release string. The thing disappeared
straight away and I soon saw the booster falling
back to earth, close to the launcher so I looked
up. I couldn't see it anywhere so I stood still
and listened. What seemed like a good 10 seconds
later, there was a distant thud and I had some
idea of where to look.
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After 20 minutes of searching
the football pitches (I was determined to get it
- I wasn't going to go home without it), finding
assorted leaves and wondering just how far it was
burried (was there just a hole - some parts of
the ground were that soft), I eventually found it
with the nose burried 6 inches into the turf,
half way up a small hill. It took some force to
get it out of the ground but the nose wasn't
damaged, except for a small slight scratch which
was probably caused by a stone in the ground.
I paced the distance back to the launcher and
it turned out to be 121 yards
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Back at the launcher, the
landing site looks so improbable and if it had
gone only another couple of yards, it would have
gone into the longer grass and I would never have
found it (it makes you wonder what someone would
have thought later on the next year as they
discovered it if I hadn't managed to find it). The
first launch was close to perfect (apart from
trying to find the dart afterwards) and
subsequent launches were made at substantially
lower pressures. These showed a tendency to
separate late - the coefficient of drag on the
booster clearly being too low - there is nothing
to go wrong with the connector. I'll possibly use
air brakes on the booster next time.
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