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Educational Rockets 3

2020 UKRoC Cluster Combinations ?


Cluster Combinations for UKRoC 2019

If you are flying in a 50mm body tube with 18mm motors, 4 x Klima D will put you just below the 80Ns limit. They can be combined with less powerful motors such as 2 x Klima C for 60Ns as well as other C and D motors with lower total impulse.

If you are using BT-80 or 75mm tubeS you can have five Klima 18mm motors or four Estes D motors. 4 x Estes D12s will give you 67.2Ns total impulse while 4 x Klima D will get you 76. Consider the weight of your motor configurations. Estes Ds are heavy. Klima Ds weigh about the same as a Estes C.

Or your can try a mix Klima and Estes motors in a custom motor mount to dial in exactly the total impulse required.

As always, you will have to experiment with the ejection delay. SpaceCAD could be very useful but flight experiments will be the proof of the combo of delay and thrust! We have motor files for SpaceCAD, RockSim and OpenRocket. Five Klima C motors will give you 50Ns total impulse and perhaps that is a good place to start.

Our 2020 UKRoC Bundle will take four 18mm motors including Klima D9,D3,C5,C2,B4 as well as Estes C6. You can mix-and-match to dial in the total impluse required to get your entry to the contest altitude BUT they must be paired symmetrically!

This table was compiled with 2019 rules in mind so your achievable motor load may vary for 2020 if you are restricted to four motors in a 50mm body tube.

  D9-5/7/P D3-0/P C6/5/7/P C2-0/P  
Klima Cluster  Ns Ns Ns Ns Total
  Combinations 19.5 17.4 10 9.8 Impulse
Combo 1 0 4 1 0 79.6
Combo 2 3 0 2 0 78.5
Combo 3 3 0 0 2 78.1
Combo 4 4 0 0 0 78
Combo 5 2 2 0 0 73.8
Combo 6 0 3 2 0 72.2
Combo 7 2 0 2 1 68.8
Combo 8 0 2 3 0 64.8
Combo 9 1 0 4 0 59.5
Combo 10 1 0 0 4 58.7
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