Recovery set-up/airframe packing

[DJRNY]

Hello,
I'm a BAR and new to MPR/HPR and this forum. I have some questions about setting up the recovery system and packing the airframe on a MPR/HPR rocket. I'm hoping to gain some insight here, but if these have already been answered please point me to the threads. My immediate questions pertain to MPR/HPR single deploy, motor eject with tubular nylon shock cords. I realize some things may be subjective or personal preference, but I am trying to find the generally accepted best practice.
I'm putting the finishing touches on a LOC Hi Tech H45, the instructions say to attach the chute to the end of the shock cord and the nose section about 1/3 of the way down. Next in my queue is a LOC Sky Fieri who's direction say to attach the nose section to the end of the shock cord and the chute about 1/3 of the way down. After reading through a recent thread on attaching the chute to the end of the shock cord I came away with the impression this was a better method, even though most of what I have see (videos, written descriptions) have the nose section on the end and the chute about 1/3 of the way down. If I think of the section of shock cord between the chute and nose section as an "extension" of the shroud lines, this set up is essentially the same as all the LPR model kits where the shock cord and the chute are attached to the nose cone. So is this really better, or just more familiar?
I also wonder why I keep seeing reference to attaching either the chute or nose to the end, and the other about "1/3" of the way down. Why is 1/3 of the distance recommended? It seems to me, for example, that if the reason is to reduce tangles, then having the chute on the end and the nose section at least 1 length down from the end (e.g. about 2') should also work.
I have also seen different recommendations on where to put the nomex chute protector along the shock cord. While everyone seems to agree to loop the shock cord back through the button hole to keep it from sliding, I have seen recommendations to put the chute protector just outside of the airframe, and other places I've seen to put it about 2' down from the chute. Which is preferred? It also seems that if the chute is attached to the end, then putting the nomex blanket just below the nose section would be fine, as it cannot slide past it to collapse the shroud lines.
I read something somewhere about using 2 nomex blankets, one to protect the TN shock cord and the other to protect the chute. Is this common?
For airframe packing, I have seen the shock cord put in the airframe first followed by the chute burrito. This makes sense, as the chute will eject first. I have also seen the chute burrito put in first, which I suppose will help protect the TN. Which is considered best practice?
Thinking about all the stuff I've read makes me wonder about the "philosophy" of ejection. Should I think about it as the ejection charge pushes the chute and shock cord out of the airframe, or does the ejection charge push the nose section out of the airframe so that the nose section pulls the chute and shock cord out?
Finally, is the best practice set up any different for using a JLCR as opposed to not using it?

I guess I could conclude that with all the different things I have seen there is more than one way to skin the proverbial cat and maybe it all works, But if there is an accepted better way I'd like to adapt it as best practice to minimize the risk of learning the hard (landing) way.

Thanks,
Dave

 

[waltr]

1/3 cord is so the Nose and Body tubes do not hit each other during descent.

Ejection should push out the nose which then pulls out the chute and cords.
The Chute, cords and Nomex should be loose within the BT so that they easily pull out for deployment.
There are many ways to pack chute and cords that work. Also MANY threads here on TRF about this.

 

[MarsLander]

This is for NOSE deploy.

I'm in the @Onebadhawk camp of deployment. I use a two loop cord (one to booster, one to nose cone). I attach the parachute to the nose cone. Attach the nomex about 6' from the nose cone. When the package comes out, the shock cord pulls the nomex off the main.

When you have the chute part way down the cord, and the chute opens, the nose cone can fall down and swing back around through the main chute shroud lines, collapsing the chute. Having the main on the end ensures once it opens and all the other parts fall below it they can't swing back up and through... YMMV. NOTE: rubber band in the last picture is there only to hold it for the picture. Do not rubber band the burrito when you go to fly.

Hope this helps!

 

[DJRNY]

1/3 cord is so the Nose and Body tubes do not hit each other during descent.

Ejection should push out the nose which then pulls out the chute and cords.
The Chute, cords and Nomex should be loose within the BT so that they easily pull out for deployment.
There are many ways to pack chute and cords that work. Also MANY threads here on TRF about this.

Waltr,
Thanks, this is helpful. I still wonder about 1/3 the distance? I get that it keeps the nose and body from banging around during descent. But why not 1/4 of the way down the cord? Or 2' down the cord? Is there a specific reason for 1/3 the distance, or is it just a convenient way of off setting the nose and body?
Thanks,
Dave

 

[DJRNY]

This is for NOSE deploy.

I'm in the @Onebadhawk camp of deployment. I use a two loop cord (one to booster, one to nose cone). I attach the parachute to the nose cone. Attach the nomex about 6' from the nose cone. When the package comes out, the shock cord pulls the nomex off the main.

When you have the chute part way down the cord, and the chute opens, the nose cone can fall down and swing back around through the main chute shroud lines, collapsing the chute. Having the main on the end ensures once it opens and all the other parts fall below it they can't swing back up and through... YMMV. NOTE: rubber band in the last picture is there only to hold it for the picture. Do not rubber band the burrito when you go to fly.

Hope this helps!

View attachment 619719
View attachment 619720View attachment 619721

MarsLander,
This helps a lot! Thank you for your explanation.
Dave

 

[waltr]

1/3 distance is a basic 'rule of thumb' and 1/4 would also work.

What I do not like is connecting Nose and Chute at same point.
However, many others do this with successful deployment and recovery.

 

[Troy3003]

I also connect my chute directly to the nose attachment point, where the harness also connects. I like this setup because as soon as the nose starts moving, your chute is pulling out too.

 

[Handeman]

Waltr,
Thanks, this is helpful. I still wonder about 1/3 the distance? I get that it keeps the nose and body from banging around during descent. But why not 1/4 of the way down the cord? Or 2' down the cord? Is there a specific reason for 1/3 the distance, or is it just a convenient way of off setting the nose and body?
Thanks,
Dave

As @waltr said, it's a rule of thumb. There's lots of different rocketeers and they can all do something different. I like the 1/3 since I seldom have a nose cone and shock cord go through the shroud lines. Since that works for me, I've never bothered trying it other ways. They may work just as well or better, I just have no experience with them.

Don't take what you hear here as gospel, or even best practice. It's mostly opinions of people that found one way that works for them, and like me, have stuck with it. That certainly doesn't mean what I do is the best and certainly not the only way to do things.

I will say, what is good about getting all the input here is that you get lots of ideas and ways of doing things. My best advice is to experiment with them all and figure out what works best for you. Just remember, what works best for one rocket, may not be best for the next one.

Good Luck and have fun.

 

[DJRNY]

Thanks everyone. My take away is there is a degree of personal preference and more than one way works.

Handeman - I also like your point that each rocket can have it's own personal preference! I'll have to work with mine to figure out what is best for each.

Thanks!

 

[teepot]

I don't measure to exactly 1/3rd. I attach the chute about 3' below the NC and the blanket about a foot below the chute. I only used tubular nylon shock cord in a couple of my early rockets. I stopped using it because it takes up to much space. Now I only use Kevlar shock cords. I figure 8 the shock cord around my fingers and put the shock cord below the blanket in first, then the burrito and then the rest of the shock cord on top. Something I think of as critical is to Z fold the chute with the shroud lines Z folded and laid inside the last fold of the chute..

 

[DJRNY]

Thanks for sharing your set-up and airframe packing method teepot. Also, I do use the Z fold method on my chutes.
Dave