MW for steerable rocket and chute deployment

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Vertigo
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Joined: Mon Jul 08, 2013 6:58 pm

MW for steerable rocket and chute deployment

Post by Vertigo »

Im surprised I cant seem to find anything on this subject. Apologies if I missed it. My brother is a model rocket enthousiast, and he got me wondering if we couldnt put a multiwii nano in a rocket with 2 movable fins to help guide it straight up. And use the baro for chute deployment.

IN theory I think using airplane mode should work fine for the guidance, using 2 servo's to steer 2 control surfaces each. WHat Im less sure about:

-will a multiwii handle 25+g accelerations? We do not necessarily need reliable data on vertical acceleration, but Im a little worried the entire board will crap out
-How can we use baro data for chute deployment? This will probably need some coding for MW to detect the apogee.
- Will it be able to react fast enough?

Has anyone tried anything like this? I cant believe I would the fist one to try, but none of my googling got an results.

BTW, one could even take it a few steps further and make the chute steerable, add a GPS and make the entire rocket "RTL" capable.

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haydent
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Re: MW for steerable rocket and chute deployment

Post by haydent »

im sure plenty have thought about it including myself, and im not even currently building rockets (though have). my advice is to do it yourself seeking help as needed. as you say it is limited functionality and should be easy. trial and error will tell you if it can handle G's, i would think so

im not sure if baro is what you want, when do you want chute deployed? at top of flight or after some time of freefall. if at top of flight you may want to be triggered by rapid deceleration or axis inversion, as baro not all that accurate and you dont want it opening mid flight.

if after freefall of some time, then maybe baro may be usefull, otherwise maybe just a timer...

likely you would have to modify the plane mode code to get it to fly straight up rather than horizontal, though maybe you could just trick callibrate it to think it was flying horizontal when it was actually vertical.

PID's would definately need tuning, (once again most by trial and error) due to the increased speed and different flight model characteristics to a plane

so start reading the source code in the bits you are interested in and seeing how its done, learning arduino is fun !

PatrikE
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Re: MW for steerable rocket and chute deployment

Post by PatrikE »

Take a look at singlecopter.
Image
It's almost built like a rocket.
viewtopic.php?f=8&t=1882&p=17395&hilit=singlecopter#p17300

If the acc can cope with the G-forces it should be possible to detect when you're at the top.

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haydent
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Re: MW for steerable rocket and chute deployment

Post by haydent »

that looks cool, im guessing it wouldnt have very stable fast descent ?

wilco1967
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Re: MW for steerable rocket and chute deployment

Post by wilco1967 »

Correct....
Decent was lousy, as airflow is lost or even reversed during decent...

On a rocket, you might want to disable stabilization after the apogee is reached.

PatrikE
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Re: MW for steerable rocket and chute deployment

Post by PatrikE »

Sorry I'm no rocketeer but.
Is'nt the rocket supposed to descend with the nose Down
Until parachute is ejected?.

thebadtall
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Re: MW for steerable rocket and chute deployment

Post by thebadtall »

Hello, you can use MMA7361 accelerometer that has 0-g Sensor to detect freefall after apogee.
If it is only for stabilization and not for remote control you can use again the MMA7361 with an AVR (ATmega8) to command the servos.
I have made a similar project for a candy rocket but without utilising the 0-g sensor

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Leo
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Re: MW for steerable rocket and chute deployment

Post by Leo »

Vertigo wrote:Im surprised I cant seem to find anything on this subject. Apologies if I missed it. My brother is a model rocket enthousiast, and he got me wondering if we couldnt put a multiwii nano in a rocket with 2 movable fins to help guide it straight up. And use the baro for chute deployment.

....


It's been done many times.

Here just one example:


You'll find more on YouTube.

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