Gorgeous hardware. I enjoyed the reaction during the underground motor
test. I'm glad your dart recovery worked flawlessly, without the drogue I'd
guess that dart has a terminal velocity of at least Mach 2. Do you have an
estimate of your budget for that project?
I was in Poland a few weeks ago and expect to visit again next year. I'd
enjoy seeing your rockets and talking shop if you're open to visitors.
Ben
On Friday, December 4, 2015, Andrej Vrbec <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Here is a couple of videos from my latest project that was launched in
October 2015. The goal of this project was to fly above 50.000feet on a
sugar propellant (KN/Dextrose). The rocket was a boosted-dart powered by a
newly developed 110mm diameter O-9600 (36kNs) sugar rocket motor. The
design was largely based on my first boosted-dart project that flew to
+35.000feet in April 2015. Video about this earlier project can be seen
here: https://www.youtube.com/watch?v=9vcAQPJUqV0
An entire project from the start of motor development to an actual flight
took five weeks. It took three weeks to develop the motor and another two
weeks to fabricate the flight hardware and the new launch rail. The rocket
construction is very simple. Booster motor has threads on both ends.
Booster fincan is screwed on the aft end and a short section of aluminum
tube holding the booster electronics and parachute is screwed to the
forward end of the motor. Then the transition cone is attached to the
booster. Dart fincan/boattail assembly is made from stainless steel. Dart
fins are also made from stainless steel and are laser welded to the fincan.
Dart is 50mm in diameter and weighs 9,3kg (20,5lbs). Body tube is made from
filament winded fiberglass. There were two altimeters on-board the dart.
Perfectflite Stratologger CF and an ARTS-2. A BigRedBee 70cm HP GPS was
used for dart tracking. Lithium batteries were used for power. Dart
nosecone is a 8°cone and is turned from a solid mild steel.
Flight was great. When the button was pushed more than a ton of thrust
made sure that the things started to move quickly. Booster burned out in
3,5 seconds at an altitude of 4000 feet. Dart successfully separated and
coasted for more then 50 seconds to a measured altitude of 57.359feet.
18inch parachute was deployed at apogee and the dart safely landed 8km from
the launch site, where it was recovered two hours later. Booster recovery
system unfortunatelly didn't deploy and the booster made a ballistic impact
about a kilometer from the launch rail. Impact site was not located and a
cause of malfunction remains a mystery. Overall I consider the project to
be a success. The altitude goal was achieved and the motor was successfully
flight tested. What's next?
Next project will be a two stage rocket. The plan is to use the same
booster motor for a first stage and a yet to be developed 55mm, 5kNs
sustainer motor for a second stage. Preliminary simulations show that this
combination would be able to fly to well over 100.000feet.
https://www.youtube.com/watch?v=AB_TpaJn72k
https://www.youtube.com/watch?v=BWsqNXpL7qY
Andrej Vrbec