# Black Sky ARRD too expensive

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#### havoc821

I was reading an Extreme Rocketry magazine and reading about that guy's "Zues ruler of the sky" project and looked really cool. I liked his idea of dual deploy from front ejection only, in other words, the drouge and the main are deployed from the same tube. He used the BlackSky Advanced Retention and Release Device (ARRD) and it was a great idea after I figured out how everything worked. I went to the website today to see how much they cost and it was $100!!!!! That is CRAZY! Does anybody know of a much cheaper/similar way to do the same thing? Thanks. #### edwardw ##### Well-Known Member My local Ace hardware carries 1/2 nylon eyebolts. They are$1.50
I drill them out about 1" in the shank with a 1/4" bit. Then I fill it with 4fg black powder and insert an e-match. I seal it up with some epoxy. Then to hook it up I have a bulkhead that is removable. I just bolt the eyebolt to it top and bottom with nuts. I hook my drogue up to the eyebolt and then a line from my drogue to my d-bag on my main parachute. When the bolt explodes it pulls the parachute out.

Edward

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#### Austin

Havoc,

I too was ready to actually spend the money on the ARRD, but then came along Defy Gravity. This company has a cool release device called the Tether and it's nearly half the price at $65. I know of several in our club that have used it and it works great. I have one on pre-order and it should ship mid April. Carl #### havoc821 ##### Well-Known Member Carl, I was going to actually buy the ARRD because I thought it might be like$15 or so, but I was way off. Do you have defy gravity's website address? $65 is also high for me but I might check it out. I might just go with the exploding eyebolt idea. Edward, I think I understand the concept, but do you have pictures? That always helps. I'm more of a visual person. Thanks guys! #### MarkABrown ##### Well-Known Member Originally posted by havoc821 ...I was going to actually buy the ARRD because I thought it might be like$15 or so, but I was way off. Do you have defy gravity's website address? \$65 is also high for me but I might check it out. I might just go with the exploding eyebolt idea.
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Guys, I looked into making my own "knock-off" copy of the Tether/ARRD. The amount of machining and intricate parts in either unit makes the cost really reasonable. I don't think I could make one for what they're charging when you consider the cost of mistakes during fabrication and testing. Remember, you get what you pay for. High Power Rocketry is NOT a cheap hobby; also, if you don't support the vendors, they won't be around to innovate in the future. My 2 cents.

#### Ryan S.

##### Well-Known Member
I am also interested in this tether, I am thinking of building a bigger V2 but if I do I want dual deploy and it seems this is going to be the way to go.

#### edwardw

##### Well-Known Member
Here is a hand drawing of how I do the eyebolt. One thing I do though is I put a piece of coupler tube where this goes, usually I make it 6" long - in case the pieces of the eyebolt try to penetrate the tube. It took me about a year to get used to using this and fine tune it. The AARD looks like a cool device. I'm also looking at some hydraulic quick release stuff that I use and making a deployment. The tether looks cool - I will order one and see how I like it.

Hope this file helps..any questions you can ask me. Dont have any pictures as I don't have the rocket it goes in right now - my buddy is making a new aluminum ring fin for it.

Edward

#### havoc821

##### Well-Known Member
Thanks for posting the pic Edward!
I will have to go to Rocket (Home) Depot sometime and pic up some.

Mark,
I now understand everything that went into making the ARRD, at first I thought it was something simple but it must be a lot more complicated than I thought because it wouldn't be so expensive if it wasn't easy to make. I know HPR is expensive, but unlike most of you, I don't have a steady job (grass cutting). This summer I will get a job because I will finally be turning 16 , but I will only get minimum wage and all that money will go toward gas, insurance, dates, and very little for rocketry, so I guess you could say I'm kind of cheap. Maybe once I have some extra money and really get into HPR heavilly, I will get one, but not now.

#### edwardw

##### Well-Known Member
Havoc,

Home Depot probably will not have 1/2 nylon eyebolts...my local ace hardware here does, but I think they even have a flux capacitor

Edward

#### Ryan S.

##### Well-Known Member
that picture really clears it up, but howmuch force can it take?

#### edwardw

##### Well-Known Member
I have never had one fail on me, you still have 1/8 nylon on either side to hold stuff together, so it is still a very strong connection. As long as your drogue isn't ballistic I think that you are okay. If you want to know force take one to a materials testing lab - then you would get some good numbers.

Edward

#### LampertRocketry

##### Well-Known Member
Originally posted by edwardw
Here is a hand drawing of how I do the eyebolt. One thing I do though is I put a piece of coupler tube where this goes, usually I make it 6" long - in case the pieces of the eyebolt try to penetrate the tube. It took me about a year to get used to using this and fine tune it. The AARD looks like a cool device. I'm also looking at some hydraulic quick release stuff that I use and making a deployment. The tether looks cool - I will order one and see how I like it.

Hope this file helps..any questions you can ask me. Dont have any pictures as I don't have the rocket it goes in right now - my buddy is making a new aluminum ring fin for it.

Edward
It looks good for smaller projects - also the Tether is probably a good bet for smaller projects. But for BIG rockets, I don't think I would want to gamble my investment on either. I want a release device with some serious capacity and some serious HISTORY.
Murray

#### zcases

##### Member
I have another alternative to the single-end recovery method. But I need to clarify, as others have, that the time involved makes commercially available items a bargain. Ed's bolt is pretty neat too, and if it works reliably a great bang for the buck (literally).

You can view an animated movie of my recovery device, which is another play on the old pyro-release concept, on my website.

#### LampertRocketry

##### Well-Known Member
Originally posted by zcases
I have another alternative to the single-end recovery method. But I need to clarify, as others have, that the time involved makes commercially available items a bargain. Ed's bolt is pretty neat too, and if it works reliably a great bang for the buck (literally).

You can view an animated movie of my recovery device, which is another play on the old pyro-release concept, on my website.

Had a look at the AVI of your pyro-release device. Looks very much like the old Blacksyd PRD, which had a pin that moved sideways as I recall.

I haven't been in this hobby long enough to have met anyone that used the old Blacksky unit; but there must have been a reason for them to switch from that device to their new, completely different design, ARRD device, which releases a plunger that is captured by a ball-bearing raceway.

Your (and the Blacksky) PRD looks relatively simple to construct. I wonder what experience you have had with it to date?

Regards,

Murray

#### zcases

##### Member
I actually had an old PRD - I really liked the original Black Sky concept, but the design in my opinion had many weaknesses which I have dealt with in my latest design as you saw on the website. This can be reloaded without removal from the rocket, access to the chamber is right through a set screw hole that is off axis from the release pin. It is structurally much stronger (my PRD bent with a 14lb rocket). It is very light, strong and simple, with no need for springs, and releases very smoothly. Next time I'm static testing motors I should get a close up video of it releasing an actual load. Again Scott Bartel deserves a lot of credit for his works, like others have said, his ARRD is a great deal.

Scott