Chute and shock cord loading preferences?

The Rocketry Forum

Help Support The Rocketry Forum:

billdz

Well-Known Member
Joined
Feb 11, 2017
Messages
1,333
Reaction score
103
I was watching some of the more experienced guys at last weekend's club launch and noticed a number of significant differences, with each person swearing by his particular method. I'd appreciate hearing from this group's thoughts about the following:
* What do you put in first, the shock cord or the chute? (Which is closer to the motor, chute or shock cord)
* Which side of of the chute do you put in first, the side with the shrouds or the side at the top?
* When using electronic deployment with a charge on the bulkhead near the chute, how do you protect the chute? Dog barf covering the charge canister or something else?
 

Handeman

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
7,868
Reaction score
433
Location
Stafford, VA
I usually put the shock cord in first. I figure as it gets pulled out, it will help pull the chute out since the ejection charge doesn't really push it out much unless it's tight in the tube like a piston.
I fold my shrouds inside the chute so I guess I would say the chute, since the end where the shrouds attach to the cord goes in last. Only reason is if I'm using a chute protector, it usually has better coverage on the other end.
I always use dog barf, just to keep from burning holes in the chute protectors. I don't use much, but enough to keep the flame directly off the protectors.
 

Bat-mite

Rocketeer in MD
Joined
Dec 5, 2013
Messages
11,519
Reaction score
2,230
Location
Maryland
Same as Handeman, except I don't use dog barf, Maybe I'll start, as I am tired of having to wash soot off my Nomex.
 

AfterBurners

Well-Known Member
Joined
May 8, 2012
Messages
7,970
Reaction score
537
Good questions. I put the shock cord in first. Depending on the length of the shock cord I lik eto fold it into small sections and use a rubber band or loosely tape the cord, which makes it easier pack and less chance of tangling.

I then pack the chute. As far as folding I make sure all the shroud lines are lines up and not crossed. I put the top of the chute in first. The Apex.
 

blackjack2564

Crazy Jim's Gone Banana's
TRF Supporter
Joined
Jan 18, 2009
Messages
9,151
Reaction score
1,325
Location
Savannah Ga
The few low/mid power I have, all use Kevlar cord & kevlar/nomex chute protectors.

When motor eject: cord goes in first followed by parachute folded/rolled with shroud lines inside, all wrapped in kevlar burrito. This is slid in fincan closed end first.

All DD have Kevlar Y-harness in fincan. Shock cord attached to that. Ends that connect to av-bay [where ejection charge lives] have first 1-2 ft wrapped with masking tape to protect from blast.

Some shock cords are tubular Nylon, some kevlar, depending on..........

see here for pics {this is a sticky at top of high power page by the way]

https://www.rocketryforum.com/showt...ASS-KIT-BUILD-quot-STARTS&p=455638#post455638
 
Last edited:

woferry

Well-Known Member
Joined
Oct 9, 2013
Messages
810
Reaction score
27
Location
San Jose, CA
* Most of my HPR rockets the chute payload area is only about as long as the folded chute itself, so the shroud lines are z-folded (and blue-taped in 3-5 fold groups, usually 3-4 groups) alongside the burrito and it's all slid in at once. On my 38mm MD I need to ensure that the shock cord lines up with the vent hole, as I had the protector block the hole once and cause an early separation. This one is a tight enough fit that I'll dust the burrito/cord with some baby powder before inserting it.
* I don't pay any attention to the actual chute orientation inside the burrito, I focus more on ensuring the better-sealed end of the burrito faces the charge.
* I use kevlar or nomex chute protectors, chute wrapped inside. In some smaller rockets the protector doesn't fully surround the chute, so the burrito may be barely closed or even open at one end, this end is pointed away from the charge. Or the slit in the protector where the quick-link/shock cord attach may leave the chute a bit more exposed, if so I'll face that away from the charge.
 

T-Rex

Ordinary Average Guy
TRF Supporter
Joined
Jul 22, 2011
Messages
3,051
Reaction score
75
Barf, cord, then blanket wrapped chute. Many of my cords are kevlar. Those that aren't have a nomex protector.
My thought is that when the cord gets jerked, the chute comes out first. In the event that it isn't fully ejected, it may work itself out in the wind. If the chute gets free, the shock cord will be pulled out.
Many of my models have a baffle, but I still throw some barf in to help protect things. Call it cheap insurance...
 

billdz

Well-Known Member
Joined
Feb 11, 2017
Messages
1,333
Reaction score
103
I've also been doing barf, cord, nomex-wrapped chute, but yesterday someone offered an interesting argument for putting in the chute before the cord. His theory is that, if for some reason the barf fails to provide adequate protection, he'd rather have the hot stuff hitting the nomex rather than the cord. A broken shock card results in a harder landing than a burned chute.
 

Rockiteer

Well-Known Member
Joined
Jul 13, 2017
Messages
106
Reaction score
0
Okey, I'll bite... What is dog barf? Returning rocketeer after a 50 year hiatus. Back in my day we stuffed a wad of toilet paper or paper towels in first along with a good dose of Johnson's baby powder then the chute/shock cord. The baby powder served as a white poof of smoke in the sky when the ejection charge detonated plus it helped in slicking the tube so the chute/shock cord would deploy easily.
 

timbucktoo

Well-Known Member
Staff member
TRF Supporter
Global Mod
Joined
Jun 13, 2014
Messages
8,773
Reaction score
1,565
Location
Cocoa Beach
Okey, I'll bite... What is dog barf? Returning rocketeer after a 50 year hiatus. Back in my day we stuffed a wad of toilet paper or paper towels in first along with a good dose of Johnson's baby powder then the chute/shock cord. The baby powder served as a white poof of smoke in the sky when the ejection charge detonated plus it helped in slicking the tube so the chute/shock cord would deploy easily.
dog barf is cellulose insulation.
 

billdz

Well-Known Member
Joined
Feb 11, 2017
Messages
1,333
Reaction score
103
If by "toilet paper or paper towels" you mean regular bathroom/kitchen paper, that's dangerous, they are flammable and can ignite. If you mean recovery wadding (looks like toilet paper but is not flammable), that is still used, especially in smaller rockets, but for larger rockets most people use cellulose, nicknamed dog barf.
 

samb

Lifetime Member
Joined
Jan 22, 2009
Messages
4,090
Reaction score
501
Location
Plano, TX
Okey, I'll bite... What is dog barf? Returning rocketeer after a 50 year hiatus. Back in my day we stuffed a wad of toilet paper or paper towels in first along with a good dose of Johnson's baby powder then the chute/shock cord. The baby powder served as a white poof of smoke in the sky when the ejection charge detonated plus it helped in slicking the tube so the chute/shock cord would deploy easily.

Hmm... did you start many grass fires with that mess back in your day ? Cellulose attic insulation is flame retardant and a bale purchased at your favorite big box home improvement store lasts for years. And it looks like dog barf ! :)

dog barf.jpg


Many of our fine vendors sell squares of nomex cloth in various sizes.

nomex.jpeg

Much better and safer wadding choices available.
 

Rockiteer

Well-Known Member
Joined
Jul 13, 2017
Messages
106
Reaction score
0
If by "toilet paper or paper towels" you mean regular bathroom/kitchen paper, that's dangerous, they are flammable and can ignite. If you mean recovery wadding (looks like toilet paper but is not flammable), that is still used, especially in smaller rockets, but for larger rockets most people use cellulose, nicknamed dog barf.
Have to remember I have been out of the hobby for about 50 some odd years and just getting back into the craft. Back in the day we used toilet paper and Brawny paper towels as wadding. Sometime newspaper and the last time I looked Texas is still there... underwater but still their. Appreciate the update. We have definitely come a long way since the wild west days of model rocketry. But really... Dog Barf? Interesting choice of words.
 

Rockiteer

Well-Known Member
Joined
Jul 13, 2017
Messages
106
Reaction score
0
Hmm... did you start many grass fires with that mess back in your day ? Cellulose attic insulation is flame retardant and a bale purchased at your favorite big box home improvement store lasts for years. And it looks like dog barf ! :)


View attachment 326757


Many of our fine vendors sell squares of nomex cloth in various sizes.

View attachment 326758

Much better and safer wadding choices available.
Excellent! Thanks for the resource. Have to remember I've been out of the hobby for some 50 years and just getting back into it. Yes, back in the day we used toilet paper and sometimes newspaper for wadding. The last time I looked Texas was still there so I guess all of us juvenile pyromaniacs did not burn the place to the ground during those long, hot summers in 1968.
 

samb

Lifetime Member
Joined
Jan 22, 2009
Messages
4,090
Reaction score
501
Location
Plano, TX
Excellent! Thanks for the resource. Have to remember I've been out of the hobby for some 50 years and just getting back into it. Yes, back in the day we used toilet paper and sometimes newspaper for wadding. The last time I looked Texas was still there so I guess all of us juvenile pyromaniacs did not burn the place to the ground during those long, hot summers in 1968.
No worries, I did alot of knucklehead s__ back in the day too. I try not to do as much knucklehead s___ now. :wink:
 
Top