HPR 54mm Min Diameter FG rocket. Looking for shock cord attachment ideas.

Hi all,,

I'm putting together a Min Diameter Hawk Mountain Transonic II (54mm Dual Deploy)

The instructions have one glueing the booster shock cord to the inside of the body tube after fraying it a bit (Estes style without the tea bag). I'm not real keen on that idea. I do like a solid connection for my kevlar cord and as little in the way as possible to get my drogue out of the 54mm md rocket. I have been looking at either a center ring with eyebolt glued in some where or one of the Aeropack MD motor retainers. I don't need it for motor retention but it would make a great anchor for the drogue's cord. With either of those options do you drill a hole in the booster to dribble epoxy in where center ring or retainer goes and then fill the hole with epoxy??

What is absolutely the best way to anchor your drogue shock cord in a MD 54mm rocket?

Thanks in advance

Chris

V2rocketeer said:

What is absolutely the best way to anchor your drogue shock cord in a MD 54mm rocket?

Click to expand...

Use motors with eyebolt closures.

dixontj93060 said:

Use motors with eyebolt closures.

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I was really leaning that way,,, but my CTI pro 54's are not recommended for recovery that way.

https://www.pro38.com/pdfs/Retainer_Endorsement.pdf

Not sure if it is because of the plastic the adapter screws into or another reason.


Chris

V2rocketeer said:

I was really leaning that way,,, but my CTI pro 54's are not recommended for recovery that way.

https://www.pro38.com/pdfs/Retainer_Endorsement.pdf

Not sure if it is because of the plastic the adapter screws into or another reason.


Chris

Click to expand...

The Aeropack min. dia. retention is a different approach. I am speaking of a 54mm threaded/tapped forward closure: https://www.wildmanrocketry.com/ProductDetail.aspx?product=3155.

You can put a birch ply bulkhead in the tube with a u-bolt attached for the recovery gear to attach to. I use a removable bulkhead retained by socket head screws through the airframe into the side of the bulkhead.

You can also put a t-nut through the middle of the bulkhead for motor retention.

dixontj93060 said:

The Aeropack min. dia. retention is a different approach. I am speaking of a 54mm threaded/tapped forward closure: https://www.wildmanrocketry.com/ProductDetail.aspx?product=3155.

Click to expand...

Wow thanks

I haven't seen one of those before. Now to try and find one locally or see what the postage is to Oz

Chris

Zebedee said:

You can put a birch ply bulkhead in the tube with a u-bolt attached for the recovery gear to attach to. I use a removable bulkhead retained by socket head screws through the airframe into the side of the bulkhead.

You can also put a t-nut through the middle of the bulkhead for motor retention.

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Do you have any pictures of this..?

Or you could just keep it simple and do this:https://www.rocketryforum.com/showthread.php?119921-Putting-an-eyebolt-into-Pro38-forward-closure


Put eyebolt in front closure after dumping out the BP... I do this all the time. No need to worry about where to put the permanent attachment glued in the tube [Aero-pac]


Edit: never-mind ,I see you were in the above mentioned thread.

If the eyebolt is glued to the motor then is motor retention simply friction fit with tape or by some other means?


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Jason328K said:

If the eyebolt is glued to the motor then is motor retention simply friction fit with tape or by some other means?


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Click to expand...

I have an AEROPACK retainer on the back of the rocket. The motor is not going anywhere. I'm just trying to figure out how to mount my shock cord easily and effectively.

On 54mm CTI, I just dump out the BP, sand the inside of the BP well and clean it with a little alcohol, and then pot my 1/8" Kevlar harness into the well with epoxy.

Jim

or like this on the AT DMS motors



Tony

Not wanting to use an external retainer, such as an Aeropack retainer, due to drag considerations and with the shock cord attached directly to the motor, is the motor retained by friction using tape?


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V2rocketeer said:

Do you have any pictures of this..?

Click to expand...

I don't have any of that rocket easily to hand. I do have a couple of a nose cone mount I made for a 38mm rocket which uses the same principles. In the larger rocket you can also put a T-nut through the middle (opposite side to the U-bolt) for mounting the motor using all thread from the motor forward closure into the T-nut.

In the first pic when the socket head screws are fully tightened they are flush with the surface of the NC shoulder. On bigger rockets the curvature of the tube vs the flat top of the socket screw is not that noticeable and you can file the head down if you like to make it curved too.

Thank you Zededee

I was having a hard time picturing what you were saying

No problem - I'm also considering epoxying a fiberglass plate on the front to protect the surface from ejection charges - that starts to make it a little thick for length of those U-bolts to go through though. Still working the details out.
For your usage you could sandwich the plywood with fiberglass plates to protect against a cato from below and the ejection charges above.

Errmmmm.... Bumping this thread from ages ago. I’ve successfully epoxied 24-29mm MD rockets the shock cord specifically. I have a 54mm MD MAC Hyper 54 kit slightly concerned about epoxying the shock cord too. Same as OP not concerned with motor retention. It’s got a Fastback retainer for motor.

Another trick I know of is using a hole drilled in BT then putting a aluminum dowel across it (cross pin) then epoxying the dowel in place. I love Tony’s idea.

With my L1 rocket it separated at Body tube to shock cord attachment twice via epoxy and it was only 3.34 pounds. Just having doubts of epoxying it.