Hi guys,
Ok, I have spent far too long running numbers without any results, and no matter who I ask or what I read... I'm going in circles. Can someone who uses or knows both propep and burnsim please explain this nonsense to me.
When I plug the lsp* number from propep (Isp* to my understanding refers to characteristic ISP which means the specific impulse of the propellant at 1000 psi without the benefit of an expansion cone getting this from Prof. McCreary) into Burnsim I get great results since the Isp* is 195. High, but with high solids and Al, not unreasonable.
However, Propep also gives me a C* value, but a rather low one one- 5104. When I plug in 195 for the Isp* in burnsim it auto-fills the C* value to 6270...when I plug in the C* value of 5104, it auto-fills the Isp* value to 159.. which seems low.
So, which value would you trust, I'm leaning towards Isp* right now because even if the value is way too high, at least the motor won't CATO as a result, but I'm a perfectionist, and I want to understand why the programs are being so non-compliant.
We have great thrust data, and decent pressure data from our characterization tests, something as simple as the simulation program should not be holding us up.
If this post violates the limits of the non-research category by all means take it down, but first, please DM me and tell me what's the problem.
Thanks,
Jack
Ok, I have spent far too long running numbers without any results, and no matter who I ask or what I read... I'm going in circles. Can someone who uses or knows both propep and burnsim please explain this nonsense to me.
When I plug the lsp* number from propep (Isp* to my understanding refers to characteristic ISP which means the specific impulse of the propellant at 1000 psi without the benefit of an expansion cone getting this from Prof. McCreary) into Burnsim I get great results since the Isp* is 195. High, but with high solids and Al, not unreasonable.
However, Propep also gives me a C* value, but a rather low one one- 5104. When I plug in 195 for the Isp* in burnsim it auto-fills the C* value to 6270...when I plug in the C* value of 5104, it auto-fills the Isp* value to 159.. which seems low.
So, which value would you trust, I'm leaning towards Isp* right now because even if the value is way too high, at least the motor won't CATO as a result, but I'm a perfectionist, and I want to understand why the programs are being so non-compliant.
We have great thrust data, and decent pressure data from our characterization tests, something as simple as the simulation program should not be holding us up.
If this post violates the limits of the non-research category by all means take it down, but first, please DM me and tell me what's the problem.
Thanks,
Jack