Deployable Hatches

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drewnickel

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Hello guys, I was wondering if anyone has had experience opening a hatch or port on a rocket payload at or around apogee to expose an internal payload. I have thought of using spring loaded doors and servos, or using a solenoid to push the panel open while the payload is operating, but wanted to see what others have done. If it only had to open a spring loaded hatch would be the way to go, but the hatch needs to be able to close prior to landing.
 

kjohnson

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There was an example of an air sampling payload that used a marble on a spring as a valve so that while the model was under thrust the mass of the marble compressed the spring and opened the sample chamber.

If the model is large enough, an arduino driving a servo could open and close a hatch, either a sliding door or a hinged one. Depends on what you are trying to do.

kj
 

dr wogz

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I believe a few of the newer altimeters have an output that can drive a servo or throw / signal a switch..

(is this the best forum for a question like this?! maybe techniques or .. might be a better choice?)
 

drewnickel

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This rocket is a very large rocket sampling air at high altitudes (~10,000+ feet). We have a 4 inch diameter airframe, so we can fit a reasonably large payload in the rocket. Reason I asked here is usually this kind of mechanism is most likely to be used in payloads for a competition rocket.
 

Exactimator

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A few years ago we had a TARC team at our field who built speed brakes into their rocket. IIRC, they cut two or three small rectangles spaced radially around the body tube, hinged at the forward end. They used an Arduino to drive a servo that opened and closed the speed brakes. When the brakes opened, the interior of the rocket was exposed.

I didn’t get a good look at how exactly everything was built, but during ground pre-flights the servo opened and closed the brakes smoothly. The rocket flew well and they qualified for Nationals. Sorry I don’t have more info but the short answer is yes, using a servo to open hatches has been done successfully.
 

TimothyG

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We did an arduino controlled solenoid actuated airbrake system like was mentioned above. If you want pictures of the home made hinges I can find some.
 

MikeyDSlagle

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I've brainstormed this a few times. I wanted to have a hatch to open and close via servo or small motor turning a threaded rod. I did a few "napkin" sketches and started a CAD file but haven't looked back at it.
Eggtimer Classic has capabilities to control a servo and still have two pyro channels.
Quantum can control a servo and have one pyro channel.
Proton has 6 outputs with 3(?) being able to control servos.
Of course Arduino would be more customizable. I got an UNO for Christmas and hope to revisit my hatch ideas again.
 

cerving

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I've brainstormed this a few times. I wanted to have a hatch to open and close via servo or small motor turning a threaded rod. I did a few "napkin" sketches and started a CAD file but haven't looked back at it.
Eggtimer Classic has capabilities to control a servo and still have two pyro channels.
Quantum can control a servo and have one pyro channel.
Proton has 6 outputs with 3(?) being able to control servos.
Of course Arduino would be more customizable. I got an UNO for Christmas and hope to revisit my hatch ideas again.
Actually, both channels on the Quantum can handle servos. The only reason that the Proton can only handle servos on three of the six channels is that I ran out of board real estate for the dedicated servo pads... they come right off the logic drivers instead of the outputs, so you don't have to mucky muck around with extra resistors like you do on the Classic & Quantum.

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TimothyG, that's some nice looking hardware you got. Judging from the size of the build, this isn't a trivial project... gotta be going up on a pretty decent motor.
 

TimothyG

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Went up on an M2000R twice. Second time it wasn’t recovered unfortunately. I made the hinges from barstock myself. Made the centering rings from laminating carbon fiber with aircraft cedar plywood. Then machining the rings. Blue tube was a great material to work with but if I did it again I’d keep the internal motor tube carbon fiber and blue tube external. Ended up remaking the aft most centering ring do to faster landing speed cracking the first one. Overall it was an incredibly steep learning curve. I’m planning on making a mark 2 in the future and I’ll be running a pair of protons for flight computers and airbrake control. Then I’ll run my RRC2+ as pyro control drogue and quark on the tender descender.
 

MikeyDSlagle

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Actually, both channels on the Quantum can handle servos. The only reason that the Proton can only handle servos on three of the six channels is that I ran out of board real estate for the dedicated servo pads... they come right off the logic drivers instead of the outputs, so you don't have to mucky muck around with extra resistors like you do on the Classic & Quantum.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TimothyG, that's some nice looking hardware you got. Judging from the size of the build, this isn't a trivial project... gotta be going up on a pretty decent motor.
I did not know that. Thanks. So the Proton can only handle three servos. But it can still do high output "pyro" on all six channels correct?
So its possible to do four charges and two servos?
 

TimothyG

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Personally I found it far easier to isolate scientific payloads and secondary flight functions from pyro computers. Have a team for recovery that chooses and arranges pyro controllers and a team for other stuff. Our science team had multiple failures in process we learned from but our recovery team managed to have fewer problems as a result of the separation of teams.
 
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