Thursday 12-05-2011 – What started out to be one of the most relaxed preparations turned out to be one of the most demanding last minute propellant casting jobs in years. Because the launch campaign in September the year before was cancelled, all grains for both the DECA III and the H13A2 were already cast. These were then vacuum sealed and stored at room temperature for about 8 months. The grains was checked regularly. Therefore the only expected preparations needed for the DECA III were to solder the recovery charges, program the RDAS tiny and pack the parachute afterwhich I would drive to the hotel and enjoy a nice cold beer in the bar, or so I thought. At 11:00 I inspected the Thrust grain and broke the vacuum seal to give the grain a final inspection and not to have any unpleasant surprises on the launch day itself. It wouldn’t be the first time that Murphey would pay us a visit. What I found out was a gummy like grain which was quite tacky indicating that somehow the grain had absorbed a significant amount of moisture. It was even possible to peal of / delaminate some of the outer layer of the free standing grain. A quick check on the available materials showed that a new 1700gr grain could be cast within a couple of hours. A call with NERO HQ confirmed that we could not take any risk and a new grain would need to be cast.
So most of the day was spent casting the freestanding grain and prepping a new booster grain with a BP/Mg charge. The grain turned out to be great with a cylindrical length of 217mm and mass of 1707gr which results in a density of 92%. No further machining would be required and the grain could be flown as-is. At around 19:00 the car was packed and I drove out to the OTCVust shooting range / launch site were the motors were prepared. Assembly of the DECA 12 grain motor was straightforward. For some reason the forward bulkhead of the Thrust motor would not fit through the front end of the motor no matter what was tried (this is a typical example of the “ASK-factor”). It was decided to coat the inside of the casing with some vaseline and push the forward bulklhead into place through the nozzle end. This turned out to work and after this small delay also the Thrust motor was quickly assembled and placed into the motor shed were several other motors from the NAVRO & DARE were already stored. At around 21:30 it was time to head to the hotel, get a hot meal and we were able to finalise the work on the DECA III rocket around 1:30.
Friday 13-05-2011 – Weather was comforatble with a temperature of 20°C and 50% cloudy with clouds at 1100 – 1500m. This was the best weather we had seen in years. Wind was 6-7m/s blowing from the West. The launch schedule was revised after a swift prep of the DECA III. 1) the DECA III at 11:00, 2) French Quark-Meson from GEA at 12:00 and 3) the H13a2 at 13:13 on Friday the 13th. JV also visited the launch day to test his liquid/liquid rocket motor. Quite a crowd had gathered at the NAVRO / DARE as tbe combined launch had a total of 8 rockets to launch. Furthermore there was some national media coverage regarding their Stratos II project which will sure benefit the exposure of the amateur experimentel rocketry community in the Netherlands. The joint launch day was a succes and organisation + communication between both parties works better each year. Maybe next year we can stay in the same hotel again and share ideas? Once again the launch rail was again easily erreted and set at 20° azimuth with an elevation of 84°.
DECA III – As stated above the assembly of the DECA III was quick and easy. It comprised of connecting the motor to the recovery section with a small d-shackle, power on the GPS tracker, slide the recovery section over the motor coupler and secure it with 2 small 5mm wide aluminium tapes. A test SMS was received to check the function of the GPS tracker and proved to be accurate within a 2m range. It was soon inserted into the launch rail, recovery charges armed and the motor igniter was connected by the LCO. A 8 gram ignter (with 5 gram BP abd 3gram magnesium) charge was used to ignite the DECA 12 grain KNER motor. After a 10s count down right at 11:00 the motor igniter popped and after the initial spike the motor slowly came up to pressure with the rocket leaving the launch rail at 20 m/s and only 4G acceleration. Due to the wind it changed trajectory a mere meter above the rail after which the motor came up to full pressure with the rocket heading in the wrong East – SouthEast way. This slow start up phenomenon is typical for KNER propellant and was also observed during the static test . However calculations showed that if the start up delay was similar to the static test the rocket would have reached a sufficiently high enough speed to stabaly exit the rail. The start up delay was slightly longer than anticipated and unfortunately took place above the rail. Observers stated the rocket was not stable and cork screwed agressively when under power. It was soon lost in the clouds. I could not get a position SMS from the GPS tracker and concluded that the rocket would have made a ballistic trajectory and was considered a loss considering the wide spash patern. However Friday the 13th pulled a trick and rather having bad luck I had a healthy dose of good luck and the rocket was recovered only 3 hours later from the middle of nowhere. Chances of finding the rocket were about one in a milion. It had parachuted as designed and was recovery with minimal damage. The minor damage was inflicted to the payload and likely occured when the motor and payload clashed while under main parachute. The RDAS indicated that apogee was reached at 2300m and missed its simulated apogee of 2990m by 700m due to its erratic course change.
Click here for a video clip of the onboard camera: DECA III – Flight I – Onboard web – 13.05.2011
Click here for a video clip of the lift off as seen from launch control: DECA III – Flight I – Ground video web – 13.05.2011
Click here for an interesting post flight analysis DECA III by BO – H14C flight analysis presentation (7) the reports includes an interesting analysis of the RDAS, IR sensors & onboard camera.
Quark-Meson – The French had their own minor assembly problems and it took a lot longer than expected to prep their rocket. So they postphoned the launch to the next time window. The Quark-Meson was a beautifully crafted rocket with a rather unique design: the recovery & payload section were mounted on a tower above the motor. This time the APCP motor had a revised forward closure. Back in 2004 I had seen the motor to burn through at the forward closure right after ignition. This time the forward closure held and the rocket had a perfectly straight flight to approximately 1km. The single stage parachute deployed on time by means of a pyro bolt actived lateral ejected hatch and landed close to the rail without a scratch. The flight was celebrated with a magnum bottle of triple beer which was much appreciated. Hopefully this bright spirit group will be back in September to fly again.
H13A/2 – Because the Quark-Meson was not launched in correct launch window the NERO missed it’s oppertunity to launch the H13 at 13:13 on Friday the 13th. Nonetheless, assembly was straight forward and again test SMS was received to check the function of the GPS tracker. After a quick countdown the H13 made a perfect flight. The freshly casted grain worked fine although there was a short start up delay. Likely caused due to the a slightly tacky grain which was not de-hydrated over a week. Motor functioned normaly
Click here for a video clip of the lift off as seen from launch control: H13A2 – Flight 2 – 13.05.2011
