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Old Aug 17, 2012, 12:04 PM
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richie967's Avatar
Cardiff, UK
Joined Aug 2008
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Parachute Recovery question..

Thought this would be the best category to post this question, but do correct me if i'm wrong....

I am interested in building a small parachute for use on my rc plane for recovery while testing an autopilot system. I would like some help if possible.

Airframe weight = 4.5 kg
Desired sink rate = 2.5 metres per second

I have worked out that the chord of the parachute is going to be around 2.5 metres. Here are the challenges I thought someone here may be able to help me with.

1. What would be the best way to deploy the parachute in the event of an emergency?

2. Where may i get a 2.5m dia parachute?

3. Where do you think the best place to storte the chute on the plane, I am thinking the apex of the cathedral tail at the rear of the plane near the elevator...

If anyone has any thoughts, help or comments, I'd like ot hear them.. positive or negative!

Rich
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Old Aug 17, 2012, 08:50 PM
I live my life 12oz at a time
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United States, FL, Miami
Joined Nov 2011
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Funny, I was thinking about how a system like that would might just the other day.

#1 - How about through a latch triggered by a switch on the TX and/or programed as a fail safe on the Rx?

#2 - Look in military surplus stores. The army uses small chutes for a wide variety of things such as flares. However, you best best may be amateur rocket chutes. Many RC stores seems to cater for the rocketry crowd as well. Of course, ebay is always your friend..
Ebay Link 1
Ebay Link 2

#3 - I suspect this would still mean the Plane would hit its nose pretty hard. Keep in mind chutes rarely result in a feather like landing (ask me how i know )... Why not put it over the CG in the hope the plane would "elevator" land?

I am very curious to hear more about your progress... let us know how it goes...

Good luck!
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Old Aug 20, 2012, 09:16 AM
SPOOOOOOON!
Joined Oct 2006
354 Posts
Also a chute that size when folded will be pretty bulky. Better to have it over the wing.

Deployment can be as simple as a servo that releases a loop of elastic that is wrapped around the chute and airframe. I use a similar system to turn my Radian into a tug for lifting other gliders.

kj
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Old Aug 21, 2012, 01:52 AM
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Using this calculator with the height above sea level set to zero, it looks like you'd need a 4.25m chute to get a 2.5m/s descent rate:

http://www.rocketreviews.com/descent...alculator.html

"For a rocket weighing 4.5 kilograms with a round parachute which is 425 centimeters in diameter, the descent rate is approximately 2.53 meters per second (9.12 kilometers per hour).

The descent time from 1000 feet would be about 120 seconds.

The recommended parachute for a rocket of that weight is one with a diameter of about 2.24 meters."

Here's a great source for chutes:

http://aeroconsystems.com/cart/parachutes/

The 60" chutes are beautifully made and very light weight for their diameter, but even they weight 325g. They're from a military mortar flare round.

Quote:
Originally Posted by richie967 View Post
Thought this would be the best category to post this question, but do correct me if i'm wrong....

I am interested in building a small parachute for use on my rc plane for recovery while testing an autopilot system. I would like some help if possible.

Airframe weight = 4.5 kg
Desired sink rate = 2.5 metres per second

I have worked out that the chord of the parachute is going to be around 2.5 metres. Here are the challenges I thought someone here may be able to help me with.

1. What would be the best way to deploy the parachute in the event of an emergency?

2. Where may i get a 2.5m dia parachute?

3. Where do you think the best place to storte the chute on the plane, I am thinking the apex of the cathedral tail at the rear of the plane near the elevator...

If anyone has any thoughts, help or comments, I'd like ot hear them.. positive or negative!

Rich
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Old Aug 21, 2012, 02:54 AM
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clipper's Avatar
United States, CA, Lake Forest
Joined Sep 2005
140 Posts
chutes

Quote:
Originally Posted by richie967 View Post
Thought this would be the best category to post this question, but do correct me if i'm wrong....

I am interested in building a small parachute for use on my rc plane for recovery while testing an autopilot system. I would like some help if possible.

Airframe weight = 4.5 kg
Desired sink rate = 2.5 metres per second

I have worked out that the chord of the parachute is going to be around 2.5 metres. Here are the challenges I thought someone here may be able to help me with.

1. What would be the best way to deploy the parachute in the event of an emergency?

2. Where may i get a 2.5m dia parachute?

3. Where do you think the best place to storte the chute on the plane, I am thinking the apex of the cathedral tail at the rear of the plane near the elevator...

If anyone has any thoughts, help or comments, I'd like ot hear them.. positive or negative!

Rich
1. It would be best to have the parachute on a top surface, assume your fail- safe will stop the motor. You are going to cut down on the payload capacity, redundency would be better. "Return to home" GPS system is a good option.
2. For us in the U.S., Rocket Supply houses have a good varaity of chutes. We can give you several here if necassary.
3. Better to have it near C.G. Way to much weight at the tail.

Eric
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Old Aug 21, 2012, 01:54 PM
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3710'36.54"N, 116 2'46.08"W
Joined Jun 2002
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Quote:
Originally Posted by BillBlair View Post
Here's a great source for chutes:

http://aeroconsystems.com/cart/parachutes/

The 60" chutes are beautifully made and very light weight for their diameter, but even they weight 325g. They're from a military mortar flare round.
I was referring to the 60" white chute shown at that link, not the olive drab one which I don't own. The 60" chute is only $12. However, the use of two of them would cost you 650g of additional weight.

Has anyone ever done an analysis of the utility of an intention flat spin as a means of minimal damage emergency recovery of UAVs where the weight of a parachute recovery system is prohibitive?
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Old Aug 22, 2012, 11:26 PM
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Joined Dec 2010
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Try Rebel Rocketry. They are an EU-based rocketry supply vendor. Sorry, I don't have a link, but Google should turn them up.
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Old Sep 07, 2012, 12:28 PM
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Cardiff, UK
Joined Aug 2008
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Thanks all for the information

Quote:
Originally Posted by BillBlair View Post
Using this calculator with the height above sea level set to zero, it looks like you'd need a 4.25m chute to get a 2.5m/s descent rate:

http://www.rocketreviews.com/descent...alculator.html

"For a rocket weighing 4.5 kilograms with a round parachute which is 425 centimeters in diameter, the descent rate is approximately 2.53 meters per second (9.12 kilometers per hour).

The descent time from 1000 feet would be about 120 seconds.

The recommended parachute for a rocket of that weight is one with a diameter of about 2.24 meters."

Here's a great source for chutes:

http://aeroconsystems.com/cart/parachutes/

The 60" chutes are beautifully made and very light weight for their diameter, but even they weight 325g. They're from a military mortar flare round.
For some reason didn't get notified of these replies... thought no one was interested in responding!! Hence the delay!

Cheers, I am now almost at the stage where i need to make a decision on this. I am going to go with the chute size you have suggested ... ~ 2.24meters. And I will not house it in the tail. As it will have a bit of volume. I will house it on top of the fuse in front of the motor close to the COG as mentioned by the majority above.

RE: Autopilot Failsafe, I do have a return to Home failsafe set up. However the chute is not for that purpose. It is because I have had some flaky experience with Autopilots, therefore It would be primarily used if the Autopilot misbehaves. Of course in an ideal world I would simply put my efforts into ensuring I do everything possilbe to prevent any autopilot errors. I am doing this, however I would like to be on the safe side. It would have been good to house it aft of the Prop. I like the idea of housing it on top of a wing, that way if the motor is running, the parachute **shouldnt** get chopped up!

Unfortunately the US company on the ebay link does not post to UK. I will try the EU company Rebel Rocketry.

Quote:
Has anyone ever done an analysis of the utility of an intention flat spin as a means of minimal damage emergency recovery of UAVs where the weight of a parachute recovery system is prohibitive?
Unsure on this one - however such anaylsis would be interesting to help in the decision making process.

I will certainly post an update on the build and some pictures with progress of this system....
R
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Old Sep 07, 2012, 05:02 PM
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United Arab Emirates, Dubai
Joined Aug 2012
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Don't want to steal the thread but I've been thinking of installing a rec. parachute to a multirotor for a a while now. There are 2 'commercial' solutions out there made by photohigher and ecilop, but their prices are extremely high. I can't believe that using rcg members knowledge and supplies available for rocketry, we can't come up with a more affordable solution.
Basically we need a remotely triggered charge that will expedite the vertical deployment of the chute (assuming that the copter will be falling vertically down) - does this make sense?
Since my rocketry knowledge is close to zero, my biggest concern is finding a way to 'push out' the chute without burning it completely.
Like I said, this is assuming that The velocity in the horizontal axis is close to zero - fortunately copters don't glide very well.
For the purpose of discussion, let's say that the copters all up weight is around 4 kg.

Any input will be greatly appreciated!
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Old Sep 07, 2012, 07:54 PM
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St Catharines Canada
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Something like the CD3 maybe?

http://www.rouse-tech.com/products.htm

Richard
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Old Sep 10, 2012, 11:27 AM
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United Arab Emirates, Dubai
Joined Aug 2012
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This would definitely work, thank you! I'll read through specs and will try to adopt it to my hexa,

Regards,
J

Edit: I thought I'll add this in case some other multi-guy comes across this thread; some guys in france seem to be successful with a very affordable multirotor recovery system: http://www.rcgroups.com/forums/showthread.php?t=1729385
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Last edited by jamac; Sep 13, 2012 at 03:15 PM. Reason: Added a link
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Old Sep 27, 2012, 09:59 PM
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eastern pa
Joined Feb 2007
2,272 Posts
Here you go. It looks sturdy enough to handle your airplane and the price isn't out of this world.

http://www.armysurplus.com/parachutedrogue.aspx
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