RRC3 two stage question

[Ric]

I am using an rrc3 as a backup to a telemega on the sustainer of a 2 stage. During the course of a flight the sustainer rrc3 will go through several “states” and transitions eg boost, coast, slight nudge from separation charge, second boost, and final coast to apogee. Is there any chance that the rrc3 will prematurely fire the apogee ejection charge during one of those transitions? Of particular concern is the transition after boost when there would be a 3-5 delay before the telemega fires the sustainer.

 

[Voyager1]

Is there any chance that the rrc3 will prematurely fire the apogee ejection charge during one of those transitions? Of particular concern is the transition after boost when there would be a 3-5 delay before the telemega fires the sustainer.

From the RRC3 manual:

Apogee Detection Mode
While the RRC3 is actively sampling the barometric sensor to determine apogee and subsequent Drogue Event, both the LED and Piezo will be OFF. When the unit determines that apogee has occurred (by reaching a displacement velocity of 0 ft per second) it will initiate the Drogue Event. The Main Event may also activate at apogee based upon the configuration of the Deployment Mode setting (see the following “Base Settings” section if the manual for more details).

 

[Jmhepworth]

Unless your sustainer has stopped gaining altitude when the sustainer motor lights, you will be fine. I always use a second altimeter as backup deployment in a sustainer. They fire at apogee, notwithstanding all the stuff that goes on before then.

 

[Ric]

From the RRC3 manual:

Apogee Detection Mode
While the RRC3 is actively sampling the barometric sensor to determine apogee and subsequent Drogue Event, both the LED and Piezo will be OFF. When the unit determines that apogee has occurred (by reaching a displacement velocity of 0 ft per second) it will initiate the Drogue Event. The Main Event may also activate at apogee based upon the configuration of the Deployment Mode setting (see the following “Base Settings” section if the manual for more details).

Thanks this answers my question.