I'm working on a rocket project; we need to open a door to deploy the parachute. This door will be subject to great forces and must stay closed, until it gets the right signal.

I have a few questions:

  • Which of the solenoid or the electric strike can endure more strength?
  • What is the electrical circuit for a 12V solenoid or strike?
  • What can I do for the solenoid to go back to its initial position, when it doesn't have an integrated spring?

We need the door latch to return to the initial position to avoid having to dismantle the rocket to close the door during the controls.


PS: English is not my mother tongue, sorry for the mistakes.

  • 2
    \$\begingroup\$ great forces - you first need to quantify this. \$\endgroup\$
    – Eugene Sh.
    Commented Jan 13, 2021 at 16:42
  • \$\begingroup\$ Use an H-bridge to reverse current through solenoids without a spring. Position solenoid movement perpendicular to direction of acceleration. \$\endgroup\$
    – DKNguyen
    Commented Jan 13, 2021 at 16:48
  • 2
    \$\begingroup\$ Why do you need it to go to the initial position anyway? Once the parachute is deployed, you can't close the door. \$\endgroup\$
    – Eugene Sh.
    Commented Jan 13, 2021 at 16:50
  • \$\begingroup\$ May I ask what the overall budget is for this rocket and, how many folk are working on this who are involved with power supplies, logic controls and squib detonation and such like. I ask because it seems to me like you should really be taking advice from them. \$\endgroup\$
    – Andy aka
    Commented Jan 13, 2021 at 17:38

1 Answer 1


My first choice would be a spring-loaded latch with a strong spring. Then use a motor with a gear reduction stage driving a capstan. The string that pulls the latch is wrapped around the capstan.

This is slower than the options you mentioned but has the advantages of both being resistant to premature opening as well as guaranteed opening. So long as the string doesn't break, that is.

  • \$\begingroup\$ Or maybe muscle wire \$\endgroup\$
    – DKNguyen
    Commented Jan 13, 2021 at 16:54
  • 1
    \$\begingroup\$ Yes, something like this. A solenoid is a poor choice, it requires very high power to get a strong force. \$\endgroup\$
    – Mattman944
    Commented Jan 13, 2021 at 17:00

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