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ActingLikeAKid

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OK, so this is my first foray into serious high power - everything up until now has been mostly "shock cord and a chute" and deploying at under 2500' AGL.

I have a larger blue tube rocket that I'm hoping to get L2 on soon. It'll be going up close to a mile and I'd really like to get it back ;) . It's got about 18' of tubular nylon (12 to the chute, 6 to the nose) and a 36" chute, which means I'm actually going to bother with z-folding my harness.

After a couple of test-packs, here's what seems to fit best; tell me if this seems reasonable.

Starting with "just above the motor" (everything is attached to tubular kevlar that is epoxied down the motor mount)

a handful of dog-barf, just because
12 feet of tubular nylon, z-folded into 3 "packs", wrapped in my chute protector*. Chute protector is burritoed around the nylon, then folded in half, secured with a wrap of masking tape**, and stuffed down as far as it will go gently.
Section 1 of harness is attached to a quick-link. Also attached to it are:
-36" nylon parachute, secured with a Jolly Logic Chute Release set to 500'
-mylar streamer for spotting.
-6 foot section of tubular nylon to the nose.
After the protector, the mylar (rolled up and stuffed in).
After the mylar, z-folded second section of tubular nylon (except for the ~ 1 foot that I need to attach the nose)
After that, the chute (folded as much as I can to get it to fit in the tube)
After THAT, the nose goes on.

Thoughts?

*-Someone once told me, and it seemed like decent advice, to put the chute as close as possible to the top. It doesn't matter if a foot of shock cord stays in the rocket. It's a problem if the chute stays in the rocket. I figured that the chute protector, though not around the chute, ought to protect it if it's between the blast and the chute.

** Thoughts on this? I figure that even if the "wad" of harness stays together at ejection, the yank of the chute opening should pull it out.
 

MikeyDSlagle

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I would put the chute in a protector..but you have dog barf and a chute protector between the blast and chute. Never done it that way but it should work the same as wadding. And I would ditch the masking tape on your bundle. With it being burittoed and folded in half I can't see the purpose of the tape except to maybe stick to something it's not supposed to or fail to release the bundle. Yeah your chute should be out even if the tape keeps your harness from extending...I don't know...now I'm rambling.

I wouldn't do the masking tape, but that's me. Someone with more experience will chime in.
 

ActingLikeAKid

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The tape wrap on the burrito'd harness is to make it slide more easily in the tube at ejection. No tape = pretty snug fit - I need something to push it in. A wrap of tape to hold it together = slides right in.
 

John Beans

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What's your rocket weigh? Is the 36" chute large enough for a nice slow landing?
 

Bat-mite

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I'm guessing the tape will break, but I have never done it that way.
 

Banzai88

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The tape wrap on the burrito'd harness is to make it slide more easily in the tube at ejection. No tape = pretty snug fit - I need something to push it in. A wrap of tape to hold it together = slides right in.
Pretty much if you need this, you should downsize your gear or revisit your packing efficiency. That tape is going to hold on when you least expect it.....and that might lead to an unfortunate landing at terminal velocity.
 

ActingLikeAKid

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What's your rocket weigh? Is the 36" chute large enough for a nice slow landing?
According to my cheap scale, about 1250g. OpenRocket puts landing speed at around 6 m/s, 15 mph. I think that ought to be enough...?
 

ActingLikeAKid

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Pretty much if you need this, you should downsize your gear or revisit your packing efficiency. That tape is going to hold on when you least expect it.....and that might lead to an unfortunate landing at terminal velocity.
Good point. Maybe it's time to reduce the long part of the harness....
 

ActingLikeAKid

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also: I'm seeing a lot of "well, I've never done it that way...." OK, that's cool ... given my basic setup (kevlar loop, long harness to chute, short harness to nose), how would you stack that? I have no desire to reinvent any wheels.... :)
 

Zeus-cat

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I think you need a longer rocket. Seriously, it sounds like you are cramming stuff in pretty tightly. Can you get a coupler and another short piece of airframe?
 

ActingLikeAKid

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OK, attempt 2, from the bottom:
Engine, barf, burrito'd chute, both harnesses. Everything fits great. Done.
 

ActingLikeAKid

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OK, so ... Which is better? (again, from the bottom up)
protector-burrito'd chute, z-folded harness
wadded-up chute protector, z-folded harness, chute
 

OverTheTop

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secured with a wrap of masking tape**
Steer clear of this. Finds an unusual amount of strength when you least expect it. Can lead to embarrassing results.


Are you using a harness protector around the nylon, or just the flat chute protector? I had a deployment where the charge canister spat out the charge and punched a hole through my chute protector. Luckily the harness on the other side had a harness protector around it so all ended happily on that occasion. I guess if you have room for dog barf the probabilities are lower.

Also, my usual method of getting the harness out of the tube involves knotting (or otherwise) outside the airframe. That way there are two strands of nylon exiting the tube, so it is less likely that they will be cut by a windmilling airframe coming down from a great height. This is how I do most of my rockets now. You probably don't need to worry unless you are going over 10k' for this. The harness protector goes over both strands of nylon, the quicklink and eyebolt.

BTW, have you considered a deployment bag? I am a convert to these now. They give you a predictable bundle diameter and you can pack them nice and tight too!
 

ActingLikeAKid

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Steer clear of this. Finds an unusual amount of strength when you least expect it. Can lead to embarrassing results.
Duly noted. This a scratch-built HPR rocket and I really don't want to **** this up, so I'm trying to balance my I WANT TO FLY IT with some caution.
Are you using a harness protector around the nylon, or just the flat chute protector?
Just the flat chute protector. I have some extra nomex material but haven't had the time to make friends with the sewing machine...yet.

I had a deployment where the charge canister spat out the charge and punched a hole through my chute protector. Luckily the harness on the other side had a harness protector around it so all ended happily on that occasion. I guess if you have room for dog barf the probabilities are lower.
For now, I'm just doing motor eject, so a healthy dose of barf between the motor and the protector ought to get me on my way, I think.

Also, my usual method of getting the harness out of the tube involves knotting (or otherwise) outside the airframe. That way there are two strands of nylon exiting the tube, so it is less likely that they will be cut by a windmilling airframe coming down from a great height. This is how I do most of my rockets now. You probably don't need to worry unless you are going over 10k' for this. The harness protector goes over both strands of nylon, the quicklink and eyebolt.

BTW, have you considered a deployment bag? I am a convert to these now. They give you a predictable bundle diameter and you can pack them nice and tight too!
Harness protector and deployment bag are both on my list for the future. IF I can manage to get my act together and get my L2, I'm going to extend the airframe and stick a Loki K in this thing. These will be important considerations for that day.
 

Handeman

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For my motor ejection, my rule of thumb is: everything goes in before the chute! The ejection charge will expend some energy pushing things out, but most of your ejection force is going to be when the tube pressurizes and the nose cone flies off. That nose cone will drag everything else out with it. If the chute is on top, it has to come out when the nose cone pulls out the first part of the shock cord. Once the chute it out, you're golden....

Even if the rest of the cord stays in the rocket, when the JLCR lets the chute open, it's drag will get everything pulled out of the rocket. Just get the chute out, the rest doesn't matter.
 

o1d_dude

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What Handy said. First thing I want coming out of the rocket is the chute bundle followed by the shock cord sections.

FWIW, I z-fold the shock cords loosely and use slack rubber bands to keep the bundles together while loading them into the rocket.

Tape scares me.
 

soopirV

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I saw somewhere here the recommendation to switch the position of the NC and the chute on the typical harness...in other words, instead of putting the nose at the end of the harness and the chute 1/3rd in, put the chute at the end and the nose 1/3rd in. I haven't tried it yet, but it seems logical- will help keep things in a line, so minimize chance for tangling? I've got a few of my HPR birds configured like this now, but haven't had a chance to go flying.
 

ThirstyBarbarian

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I like the whole train to be stacked in the order it is to come out of the rocket, last in, first out. Typically the recovery gear does not get "blown" out of the rocket and unfurl in the open, it gets dragged out. So you want things pulled out in order. For example, you don't want the chute loaded in before the lower section of the harness, because that means the chute is going to be yanked "through" the harness, shroud lines unfurling inside the rocket and getting entangled with everything it's trying to squeeze past on its way out. So the order should be, from the bottom: lower section of harness, chute, upper section of harness. Nose cone pops off, pulls out upper section of harness, pulls out chute, pulls out lower section of harness, in order.

I would not wrap the burrito in tape. I do z-fold my long section of lower harness into bundles, and put a wrap of tape around each bundle. That helps keep things compact and organized. I usually also fold the upper section, but don't tape it.

For heat protection, I would protect the chute and the Chute Release by wrapping those inside the burrito. It sounds like you have a Kevlar leader, so that doesn't need much protection and will partly protect things above it. Some dog barf would not hurt. With the dog barf and the Kevlar leader, your harness may not need much more protection, but if you want to protect it better, you might want to use your spare piece of nomex. I have an old chute protector that got damaged and I've been cutting out patches from it to help protect my shock cords. For a 4" rocket, I cut a 4" or 5" patch and put a hole in the middle, then thread it onto the harness all the way to the bottom of the nylon cord, like a mini chute protector for the nylon cord. It's not enough to burrito the cord, but it does provide some flame resistance to the blast. If you have enough room in the rocket, you could make it even larger and maybe burrito the first bundle of z-folded harness, then load the rest in on top.

To recap, from the bottom: motor, dog barf, Kevlar leader, nomex patch, z-folded bundles of lower harness, chute and jlcr in burrito, upper section of harness, nose cone.

Good luck with L2!
 

boatgeek

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There's lots of great advice upthread. One thing I've done when I had trouble getting the chute to fit nicely in the body tube was to fold the chute into a smaller diameter but longer bundle and putting the fire blanket over the bottom of that. If the chute bundle is so long that a little of the chute hangs out the top, it hasn't been a problem. A couple handfuls of dog barf definitely helps as well.

If the chute is even kind of tight, I would make sure the JLCR has fabric of some kind (chute or fire blanket) between it and the body tube. That helps everything slide out easier.
 

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