Static Test # 1 – DECA 8 grain Rocket Motor, KNDX, March 13, 2010

Not the first time right.

Goals:

  • Use 8 bates grains stacked on top of each other in a 54mm motor.
  • Retain nozzle and foward closure by means of countersunk M3 bolts.
  • Use a 5gr BP igniter charge to boost the start up pressure to 50bar for instant ignition.

Excel file – 54mm, 4 BATES grains, KNDX 6535 flight 1 – 02.10.09

Data from video:

Video – DECA_14_-_Static_Test_I_-_13.03.2010

  • 1.39,92s – Ignition
  • 1.40,04s – End of igniter charge
  • 1.41,52s – Start of thrust
  • 1.43,24s – End of thrust / start of greyish smoke
  • 1.43,44s – No significant smoke ejected out of nozzle
  • ==> Burn time 1,7 seconds

Thrust curve   

 

 

 

 

 

  1. Peak thrust – ?N
  2. Average thrust – ?N
  3. Burn time – 1,7s
  4. Total thrust – ?Ns
  5. Propellant weight – 1165,7gr
  6. ISP, delivered – ?s

Notes:

  1. Grain making proces is as described here is excellent and resulted in 8 beautiful bates grains. Average density of 99%!
  2. Weight of the motor – loaded but excluding igniter – was 2643gr of which 1165gr of KNDX.
  3. Pyrogen coating: 4 top grains all surfaces, lower 4 grains only the ends coated with commercial 3F BP + NC laquer. BP needs to be grinded in a mortar before being mixed with NC lacquer. Total coating on all grains = 2,6gr BP.
  4. Igniter: 5,0gr (2,5gr commercial 3F BP + 2,5gr of flare).
  5. Temperature during testing slightly below 5° C with a strong wind blowing.
  6. In the heat of battle I forgot to hook up the data cable from the loadcell to the amplifier. No data collection!
  7. Only a small drop of excess Copaslib was expelled from one of the bolt holes at the nozzle end. No blow by at the o-ring although it was fully molten to the steel o-ring groove. The bolt holes in the casing do cause some damage to the o-ring and slice of small sliffers when inserting the nozzle or forward closure. Check to use “46x4mm Precisie O-ring FPM (Viton®) 75° compound 51414.”
Conclusion:
  1. I need to make detailed check lists to prevent mistakes made in the field. Small mistakes are a large waste of time and efforts. Every thing needs to be perfect which is typical for this hobby.
  2. 8 bates grains seems to works just fine although the burn time, as derived from the video, was 70% longer than expected. This could be an result of the cold weather.
  3. Nozzle and forward closure were retained perfectly by the bolts. No permanent deformation was observed although it is suspected that the MEOP was not met during this test.
  4. Although 5,1gr of commercial BP was used, divided over 2,6gr coated on the grains and 2,5 in the igniter charge, the start up was far from instant. Delay as derived from the video was 1,48s. New igniter set up to be tested.