DaveHein
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- Feb 19, 2009
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David,What makes you think that the delay burns at atmospheric pressure in the motor?
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Because of the small burning surface the pressure rise will be small but it will not be zero and it will vary with throat diameter.
You may be on the right track, but I think the pressure would have to be around 50 to 100 PSI to account for a 2:1 difference in burn rate.
I don't know much about the composition of the delay element, but I think it is similar to the APCP propellant. It contains some additional chemicals to keep it burning at low pressures. The burn rate is proportional to the pressure raised to the power of the "burn rate exponent".
I suspect that people that know the real answer to the question about burn rates are not commenting because it may get into an "Ex" discussion.
Dave