Motor Delay... Based On What Event?

[lakeroadster]

Is the motor delay based on the time from:

A) Motor (thrust) Burnout to Motor Ejection Charge​

or​

B) Motor Ignition to Motor Ejection Charge​

I always thought it was A. But I recently found out that on center burn motors the delay starts to burn at ignition.

So is it "A" for end burn motors​

and "B" for center burn motors​

​

 

[mbeels]

It is A. You're right that the delay grain starts burning at the time of ignition (for non-end burning motors), but that is accounted for in the design of the motor.

 

[dhbarr]

Is the motor delay based on the time from:

A) Motor (thrust) Burnout to Motor Ejection Charge​

or​

B) Motor Ignition to Motor Ejection Charge​

I always thought it was A. But I recently found out that on center burn motors the delay starts to burn at ignition.

So is it "A" for end burn motors​

and "B" for center burn motors​

​

The quoted delay is from burnout.

Yes, most delays start to burn at ignition -- that's why some are much thicker than others, depending on how temperature, duration, and pressure of the burn.

An end burner is essentially a giant delay grain.