Chute Ejection methods

Discussion on ground control/GSE and recovery equipment. This includes launch pads, triggers, chutes, streamers etc. Includes other items such as simulation and other computer software, etc.

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knight
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Chute Ejection methods

Postby knight » Tue Mar 16, 2010 11:13 am

Hi all, i'm asking for the advice from the general community about methods for deploying the chutes on rockets.

Obviously we have the motor ejection charge,
Pros
good for smaller rockets,
mostly reliable,
simple.
Cons
No good for larger rockets/motors
No backup
Tied to motor burnout

Black powder
Pros
Can be set to fire at a certain height
Not tied to motor in any way
Can be triggered multiple ways
Cons
Requires a firearms licence (in most states)

CO2
Pros
As for Black Powder
Doesn't rely on an explosive which could fail
No licence required
Cons
Systems are complex, heavy and expensive.

Are their any other options that i'm not considering?

One that i'm still trying to work out is using a small (A B or C) motor mounted above the nose cone, to lift the nose cone away and pull out the chute. (System is based on the Apollo tower escape system)

Please tell me if i've missed something ovbious, how do you high power people do all your chute charges.

Regards
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Re: Chute Ejection methods

Postby hybridhighflyer » Tue Mar 16, 2010 12:37 pm

I myself have been visiting this.

When dealing with J or higher rockets I have though about "weight" in a rocket a lot.

Most cases a heavy nose isnt such a bad idea. In some cases its needed for CG reasons.

I have created a low voltage phnumatic system that has a 900PSI charge and with a total weight of >200grams

This can be down scaled however removes the need for a lot of things.

You also can be very inventive with this system and connect it to electronics depending on your budget you can also make it as light as 75 grams.

The advantage of this system is as you said no licence is required. Also to reload it is a 70c co2 cylander that screws in the system.

If your rocket CATO's or becomes a lawn dart 99% sure you will be able to retreve the phnumatic valve.

This system still works on a diaphram preassure system like BP and motor ejection.

So whats the costs for this system?

Take cost of shipping out (which is difefrent dependant on supplier) and which size valve you want however 150g (cylander weighs 50g to total 200g system) is $17. This comes with the 2 screw holes the phnumatic valve and electrical inputs (obviously) all you will need to do is screw the CO2 cylander in and set the "plumbing" up inside the rocket.

This system does not have height or preassure limits and as long as the electronics kicks (constant charge) it will fire.

I have managed to eject all my rocket chutes using this system from 38mm to 152 mm.

This system does not suit every rocket however is the best "non pyro" solution I have found.

Thanks
Wayne

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Re: Chute Ejection methods

Postby cha05cat » Tue Mar 16, 2010 12:53 pm

It looks like you are looking to build this:
http://www.rouse-tech.com/recovery.htm

Although I think it still requires an e-match.
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Re: Chute Ejection methods

Postby Avachovy » Tue Mar 16, 2010 2:15 pm

and a touch of BP
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Re: Chute Ejection methods

Postby Scoop1261 » Tue Mar 16, 2010 2:57 pm

For all but the most advanced setups, a suitably sized charge of BP set off using either an altimeter or timer is by far the most efficient way of achieving successful deployment.

The type of electronic measure used to fire an event can be quite varied, but I am coming to advocate the Magnetic Apogee Detector as a failsafe measure for primary deployment.

The size of the charge required can be easily calculated for your given airframe by using any of the online calculators at the following link.

http://www.rocketreviews.com/tool_black_powder.shtml

Or by the formula that can be found on Vern Knowles' website

http://www.vernk.com/EjectionChargeSizing.htm

In any event, ground testing of your chosen deployment system should be employed in all instances.
For most folks here, the use of complex systems such as pistons, deployment bags, gas discharge and tethers is not necessary. A simply well packed & sized parachute and your personal choice of retardant wadding will get your rocket back.

More importantly, the shockloading experienced by a rocket at apogee and subsequent deployment is an area where most folks come unstuck. The loads experienced by the vehicle during this phase are by far the most severe over any of the flight profile. These loads can be minimised by using suitable lengths of shockcord and the use of materials & construction methods which will withstand the induced loading.
The loads can also be reduced by ensuring the deployment occurs at the point of slowest velocity in the flight profile.

Once again a plus for the MAD!
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Re: Chute Ejection methods

Postby RobAust » Tue Mar 16, 2010 6:14 pm

Hi Scoop,

You may have covered this in another post - could I ask why you favour the MAD for Apogee deployment and not Barometric or Acceleration ?

Equally, do you have a website I could review fro additional info ?

Wer'e about to acquire our first dual deployment altimeter and I had npt considered the MAD and headed for the MAWD as this seems a great entry level device, does most things and economically priced.

Any help would be appreciated.

Regards,
RobW
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Re: Chute Ejection methods

Postby air.command » Tue Mar 16, 2010 6:49 pm

knight wrote:Hi all, i'm asking for the advice from the general community about methods for deploying the chutes on rockets.

Are their any other options that i'm not considering?


A while back I put together a recovery guide for water rockets, and while not all options are necessarily suitable for pyro rockets, there are several others that may be applicable, and provide alternatives to the common techniques you mentioned:

http://home.people.net.au/~aircommand/recovery_guide.htm

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Re: Chute Ejection methods

Postby RobAust » Tue Mar 16, 2010 8:38 pm

Hey Scoop,

I checked my messages and you answered this for me already - sorry about that.

Regards,

Rob
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Re: Chute Ejection methods

Postby knight » Tue Mar 16, 2010 10:25 pm

Scoop1261 wrote:For all but the most advanced setups, a suitably sized charge of BP set off using either an altimeter or timer is by far the most efficient way of achieving successful deployment.


Scoop, I guess what i'm trying to get away from is BP, as (and i'd love to be corrected) I was under the impression you needed to be licensed to buy BP. While for some HPR flyers who can buy and use whatever they want thanks to their pyrotechnics licences, I don't have one of them so for the purposes of this discussion, assume BP is not an option at all.

Thats why I'm trying to determine what other people use or have contemplated, as i doubt i'm the first person to be in this situation.

Air.command, thanks for that list there are a few in there that bear thinking about. I hadn't even contimplated something as simple as a spring to push the parachute out of the rocket.

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Re: Chute Ejection methods

Postby Scoop1261 » Wed Mar 17, 2010 2:31 pm

knight wrote:
I guess what i'm trying to get away from is BP, as (and i'd love to be corrected) I was under the impression you needed to be licensed to buy BP. While for some HPR flyers who can buy and use whatever they want thanks to their pyrotechnics licences, I don't have one of them so for the purposes of this discussion,

-Knight


I cannot categorically state as fact, but I am reasonably confident, that a minimal amount of BP can be sourced without the requirement of a firearms license in all states.....ok well maybe not SA......but they are all backwards there! :D

The best way to find out the requirements is to touch base with a local gun club who specialize in antique firearms, I am sure they will have all the answers, regarding the purchase of BP in your particular state or jurisdiction and could possibly even assist with the supply.

Is there an issue in obtaining a pyrotechnics license? You would most likely need one to further step up with HPR in any case.

Obviously, a small portion of BP comes with each reload....well at least until you get up to the larger ones such as the high impulse K's, L's & M's, so to a degree, supply is not a great issue for medium sized rockets using single deploy.
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Re: Chute Ejection methods

Postby knight » Wed Mar 17, 2010 3:26 pm

Actually having just rung ACT work cover 5 minutes ago BP is only authorised in the ACT for members of black powder firearms clubs.

....Now for something a little odd.... The LPR motors sold in ACT hobby shops are illegal in the ACT. Just something that ACT work cover told me while on the phone trying to work out the regulations. I asked what the process is to get them permitted and it involves lots of paperwork and import, storage and suppliers licences. But since the laws arn't written yet, if someone was cleaver, we could get HPRs authorised for general use in the ACT...altho i'm not sure there are any launch sites actually in the ACT, the airport presents a few issues in those regards.

Unfortunatly NSW is closed this now, so i'll chase up them tomorrow.

As to obtaining the pyro licence i was under the impression it was in the order of $2000 for the course to get the licence, so yeah i suppose you could say there is an issue :P
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Re: Chute Ejection methods

Postby Kryten » Wed Mar 17, 2010 4:20 pm

knight wrote:....Now for something a little odd.... The LPR motors sold in ACT hobby shops are illegal in the ACT.

I heard something like that a while ago. IIRC, in ACT, LPR motors fall into the classification of general use fireworks, which are now illegal
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Re: Chute Ejection methods

Postby Scoop1261 » Wed Mar 17, 2010 4:44 pm

knight wrote:Actually having just rung ACT work cover 5 minutes ago BP is only authorised in the ACT for members of black powder firearms clubs.


Bugger! :(


knight wrote:As to obtaining the pyro licence i was under the impression it was in the order of $2000 for the course to get the licence, so yeah i suppose you could say there is an issue :P


Whoa!......Any idea as to why so expensive?.....I mean after all it is not for general use fireworks.

I guess I should be happy with my Dangerous Goods Security Card at $150 odd and my Special Use Pyrotechnics License at $60 odd............. :)

After a quick check of the Workcover site http://www.workcover.nsw.gov.au/licensi ... fault.aspx it appears as if it only costs $250 and not the $2K you originally thought.
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Re: Chute Ejection methods

Postby knight » Wed Mar 17, 2010 8:17 pm

Scoop1261 wrote:After a quick check of the Workcover site http://www.workcover.nsw.gov.au/licensi ... fault.aspx it appears as if it only costs $250 and not the $2K you originally thought.


Thats the fee for the licence application, but the way i read the form you need experience with handling pyrotechnics before you can apply, that was what the course was, teaching handling.
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Re: Chute Ejection methods

Postby hybridhighflyer » Wed Mar 17, 2010 8:36 pm

With tripoli level 2 you can get a specal licence for use. quote CASA regulations maybe you can pioneer laws.

Hope this helps otherwise just use a phnumatic solution.

Thanks
Wayne


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