krushnic effect

Discussions of motors from single-use and RMS solid propellants to hybrid propellants

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TRFfan2
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krushnic effect

Postby TRFfan2 » Sat Feb 11, 2017 1:30 am

Would a 24 mm MD rocket with a tailcone length of 14.5 mm and diamiter of 19.9 mm be ok?

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SpaceManMat
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Re: krushnic effect

Postby SpaceManMat » Sat Feb 11, 2017 9:35 am

Check out this NAR article

http://nar.org/member-only-reports/rd/NARAM_54_Reports_TCR25/Krushnic%20Effect%20on%20Reducing%20BP%20Motor%20Thrust%20(J.%20Dunbar,%20NARAM%2054,%202012).pdf

There is a graph in there for a c6 that shows 5mm has no effect on the total impulse. But 8mm takes it down to about 85%.
I believe it varies a lot depending on the nozzle design. Not sure you could make any rule based on one study, but I would say it seems likely that there will a loss of impulse in your case.
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TRFfan2
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Re: krushnic effect

Postby TRFfan2 » Sat Feb 11, 2017 10:42 am

SpaceManMat wrote:Check out this NAR article

http://nar.org/member-only-reports/rd/NARAM_54_Reports_TCR25/Krushnic%20Effect%20on%20Reducing%20BP%20Motor%20Thrust%20(J.%20Dunbar,%20NARAM%2054,%202012).pdf

There is a graph in there for a c6 that shows 5mm has no effect on the total impulse. But 8mm takes it down to about 85%.
I believe it varies a lot depending on the nozzle design. Not sure you could make any rule based on one study, but I would say it seems likely that there will a loss of impulse in your case.


I'm using a G150. What would I need to do to find out a limit to how long the boatail will be until the thrust is normal?

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Re: krushnic effect

Postby dhbarr » Sat Feb 11, 2017 11:09 am

Replicate that experiment with g150's? I'd think that fastening one on it's side on a fairly durable surface would be a good start in characterizing the shape of the exhaust plume.

An interesting result for the c6-5 in that test was that a tiny ring addition appeared to actually -improve- the total impulse.


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