Questions during my build LOC IV LOC Precision

Lt72884

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Ok, i have started the build and im sorta stuck on this whole parachute assembly. The instructions are kind of typed strange so im not sure what they mean:

"Attach shock cord to forward ring eye bolt. Pass loop through eye bolt, then pass shock cord through it’s own loop as shown. Don’t get any epoxy on the shock cord! Feed shock cord down one of the motor tubes out the AFT"

Its the last part where it says to feed the shock cord down the MMT and out the aft..

Next question. Am i supposed to hook the shock cord to the nose cone or the eye bolt on the bulk plate?

some pictures if anyone has any would be great. Im just waiting for the epoxy to cure on the MMT rings so i am preparing for next steps.

thanks
 
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One end of the shock cord attaches to the forward centering ring eye bolt. They tell you to thread it out the aft temporarily so that it doesn't get in the way. After epoxying the fins on thread the shock cord back out through the front and attach the other end to the bulkhead eye bolt.
Many mid/high power kit instructions are minimalist since they assume you have previous building experience.
 

samb

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Yeah, that is a little confusing since the model on has one motor tube. Anyway, after you attach shock cord to the eye bolt on the forward centering ring you stuff the shock cord into the motor tube to get it out of way before gluing the motor mount into the airframe. The warning about glue on the shock cord is there because any glue will weaken the cord over time and create a failure point.
Step 11 shows the parachute attached to the end of the cord with a quick link. But before you make that attachment you knot the cord through the eye bolt in the payload section about 3 feet from the end.
Hope this helps.

[edit] After looking at the instructions again I think Step 4, attach shock cord to centering ring eyebolt, should be done before Step 3, insert motor mount assembly into airframe. Seems to me it would be hard to access the eyebolt in the tight confines of the airframe.
 
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Lt72884

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One end of the shock cord attaches to the forward centering ring eye bolt. They tell you to thread it out the aft temporarily so that it doesn't get in the way. After epoxying the fins on thread the shock cord back out through the front and attach the other end to the bulkhead eye bolt.
Many mid/high power kit instructions are minimalist since they assume you have previous building experience.
ok, once the shock cord is attached to the motor forward centering ring and the bulk plate, where do i attach the parachute to the shock cord? i will be using a chain link.
 

gldknght

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For parachute attachment to the shock cord, this: (normally I'd use a swivel attached to the quick link, but didn't have one on hand)
 

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gldknght

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ok, once the shock cord is attached to the motor forward centering ring and the bulk plate, where do i attach the parachute to the shock cord? i will be using a chain link.
About 1/3 of the way down the shock cord from the nose / payload section. Lay out your shock cord, top half of the rocket and the bottom half. You don't want the top banging into the bottom while hanging from the parachute.
 
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ok, once the shock cord is attached to the motor forward centering ring and the bulk plate, where do i attach the parachute to the shock cord? i will be using a chain link.
Loc says to attach the parachute to the quick link on the bulkhead eye bolt at the end of the shock cord. See step 11 on the first page. Swivel optional. (Note: Edited and corrected).
Personally I would attach it to a loop further down the shock cord. And I would use an extra long shock cord because of the payload/ebay section. And IMHO heavy duty swivels are not an option, but a necessity. YMMV.
 
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gldknght

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Loc says to attach the parachute to the quick link on the bulkhead eye bolt. See step 11 on the first page. Swivel optional.
Personally I would attach it to a loop further down the shock cord. And I would use an extra long shock cord because of the payload/ebay section. And IMHO heavy duty swivels are not an option, but a necessity. YMMV.
Agreed. Like I said, I just didn't have a swivel on hand, and was looking to get this rocket finished and off my build table. I will add a swivel before the rocket's first flight.
 

Lt72884

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Loc says to attach the parachute to the quick link on the bulkhead eye bolt. See step 11 on the first page. Swivel optional.
Personally I would attach it to a loop further down the shock cord. And I would use an extra long shock cord because of the payload/ebay section. And IMHO heavy duty swivels are not an option, but a necessity. YMMV.
yeah step 11 is confusing. it says to tie a knot 3 feet down the shock cord and a picture of the chute with the word "knot"

"Knot shock cord through the eye bolt on the payload approximately 3’ from the end. Attach quick link to the sewn shock cord loop and parachute to the quick link. Make a knot in the paracord"

is my picture i drew correct? this is how i see it working, but step 11 shows it with a knot on the para cord rather than the quick link it says to use.

i see it as the loop in the shock cord has the quick link attached to it. the parachute is attached to the quicklink as well. then the shock cord is tied in a knot to the payload section eye bolt, and then tied to the base?

is this corrct for parachute placment.jpg
 
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yeah step 11 is confusing. it says to tie a knot 3 feet down the shock cord and a picture of the chute with the word "knot"

"Knot shock cord through the eye bolt on the payload approximately 3’ from the end. Attach quick link to the sewn shock cord loop and parachute to the quick link. Make a knot in the paracord"

is my picture i drew correct? this is how i see it working, but step 11 shows it with a knot on the para cord rather than the quick link it says to use.

i see it as the loop in the shock cord has the quick link attached to it. the parachute is attached to the quicklink as well. then the shock cord is tied in a knot to the payload section eye bolt, and then tied to the base?

View attachment 542748
Your picture is the way Loc says to do it.
 

Lt72884

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Your picture is the way Loc says to do it.
ok, great. Thanks. Its slightly differnt than the smaller D and E rockets i have built haha.
Random question but what if i add a large piece of square fabric to the quick link as well to create even more drag? IE, have a the parachute AND the square piece of material eject at the same time.. or is that pointless?

thansk
 

gldknght

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Most people would switch the top part of the rocket to the end of the shock cord, and put the parachute where the top part is now. I don't think I've ever seen a rocket flown in the configuration in your drawing.
 

gldknght

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The square piece of material visible in my photos above is a chute protector. It's flame proof, to reduce the need for any additional heat protection for the parachute.
Do not just add random material that could burn from the heat of the ejection charge.
 
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Most people would switch the top part of the rocket to the end of the shock cord, and put the parachute where the top part is now. I don't think I've ever seen a rocket flown in the configuration in your drawing.
Yeah, but the way Loc has it will work I think. Cuz whether you have the chute at the end and the payload section hanging from a loop or have the payload section at the end and the chute attached to a loop further down, the net effect at deployment will be chute at the top and payload section hanging a few feet down, main body of rocket hanging further down. Not the way I would do it but......... meh.
From the instructions:
2022-10-21 (2).png
 

gldknght

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Seems like there is a reason almost nobody does this.

Since the parachute would pass the payload section at ejection, I think there will be a higher risk of the parachute wrapping around the payload section?
 
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Seems like there is a reason almost nobody does this.

Since the parachute would pass the payload section at ejection, I think there will be a higher risk of the parachute wrapping around the payload section?
Either way, the chute has to pass by the payload section.
 

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I do NOT like how LOC shows to configure cord and chute. Also the why Tim at Apogee shows to do the Zephre. Here are photos of my 4" LOC Goblin setup. The Goblin is about the same size and weight of the LOC IV and is what I used for L1 cert. This also survived a delay error that was twice what it should have been (10 seconds instead of 5 second) which deployed about 100 feet from the ground without any damage.

Note the Heavy duty swivel near the BT and the extra piece ff Nomex at the BT to wrap the Nylon cord in. There is a Loop of heavy Kevlar through the eye bolt on the Motor mount's top centering ring. Then the Swivel to the nylon cord. The shock cord has a loop tiedabout a foot or two down from the nose cone/payload (important is that when suspended from chute the nose/payload does not hit the BT. Chute shroud lines go through the loop and the chute is passed through the shroud line's loop.

Chute is fold into the Nomex and rolled into a burrito.
The shock cord is Braided to absorb shock when the chute Opens. This is what will prevent damage if Delay time is off.

I have another 3" rocket with a payload bay that I stuff a 10DOF logger into and some a GPS tracker. Same setup as the LOC Goblin but connect quick link to Eye-bolt instead of nose cone.
 

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gldknght

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so which one should i do so the rocket doesnt fail? haha
I would NOT do it the Loc way. There is a possibility, if the parachute / chute protector wad is tight in the body tube, that the nose section could get blown off without taking the parachute with it.

I'd strongly recommend doing it the traditional (to me, the easier) way, with the nose section attached to the end of the shock cord, and the parachute connected about a third of the way down the cord from the nose.
 

gldknght

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I do NOT like how LOC shows to configure cord and chute. Also the why Tim at Apogee shows to do the Zephre. Here are photos of my 4" LOC Goblin setup. The Goblin is about the same size and weight of the LOC IV and is what I used for L1 cert. This also survived a delay error that was twice what it should have been (10 seconds instead of 5 second) which deployed about 100 feet from the ground without any damage.


Chute is fold into the Nomex and rolled into a burrito.
The shock cord is Braided to absorb shock when the chute Opens. This is what will prevent damage if Delay time is off.
Is there a link to a video showing how to braid a shock cord like that?
 

waltr

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Look up "crochet chain stitch" to see how then a little practice.
This is very easy to do on wider shock cords. For LPR and thin cords a crochet hook is needed but not on the larger cords. Tim at Apogee Components has a video on dong this on small Keval for LPR rockets.

Rock climbers also use this chain stitch to braid their webing for easier to carry and easy to undo when web is needed.
 

gldknght

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Look up "crochet chain stitch" to see how then a little practice.
This is very easy to do on wider shock cords. For LPR and thin cords a crochet hook is needed but not on the larger cords. Tim at Apogee Components has a video on dong this on small Keval for LPR rockets.

Rock climbers also use this chain stitch to braid their webing for easier to carry and easy to undo when web is needed.
Cool, thanks
 

Wilson1030

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I do NOT like how LOC shows to configure cord and chute. Also the why Tim at Apogee shows to do the Zephre. Here are photos of my 4" LOC Goblin setup. The Goblin is about the same size and weight of the LOC IV and is what I used for L1 cert. This also survived a delay error that was twice what it should have been (10 seconds instead of 5 second) which deployed about 100 feet from the ground without any damage.

Note the Heavy duty swivel near the BT and the extra piece ff Nomex at the BT to wrap the Nylon cord in. There is a Loop of heavy Kevlar through the eye bolt on the Motor mount's top centering ring. Then the Swivel to the nylon cord. The shock cord has a loop tiedabout a foot or two down from the nose cone/payload (important is that when suspended from chute the nose/payload does not hit the BT. Chute shroud lines go through the loop and the chute is passed through the shroud line's loop.

Chute is fold into the Nomex and rolled into a burrito.
The shock cord is Braided to absorb shock when the chute Opens. This is what will prevent damage if Delay time is off.

I have another 3" rocket with a payload bay that I stuff a 10DOF logger into and some a GPS tracker. Same setup as the LOC Goblin but connect quick link to Eye-bolt instead of nose cone.
Thanks for sharing this!
 

jmasterj

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I do it the LOC way with the parachute at the end of the harness. Was recommended by my L1 mentor. Nose cone gets attached 3-5 feet down the harness. If you pack decently you won't have any problems.
 
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