Shock cord material for lpr/mpr

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Tractionengines

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I extended my Goblin clone to fit the baffle. Really flew well with the JLCR.
NICE... What is the size of that "Streched Goblin"?
Here is a scratch built stretched fiberglass one I just finished. (Named GOBLINESQUE). Hasn't flown yet. 2.25" OD, ~32"long body tube.
20210625_122523.jpg
Flight ready, and loaded with a DMS G80-14NBT it weighs 1375grams and sims right at 1000ft. (I added a few grams for extra wadding. And I still have a little to the class 1 limit, if I add an altimiter, or beeper, etc)
20210628_082043.jpg

Mike
 

rklapp

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NICE... What is the size of that "Streched Goblin"?
Here is a scratch built stretched fiberglass one I just finished. (Named GOBLINESQUE). Hasn't flown yet. 2.25" OD, ~32"long body tube.
View attachment 473919
Flight ready, and loaded with a DMS G80-14NBT it weighs 1375grams and sims right at 1000ft. (I added a few grams for extra wadding. And I still have a little to the class 1 limit, if I add an altimiter, or beeper, etc)
View attachment 473920

Mike
Awesome. I added a couple inches. I’d do the same but not sure how to get a G motor here. I do know a guy…
 

hcmbanjo

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That sounds about right. I use a lot of TB2 in constructing the baffle plus soak the joints with thin CA. Didn’t think about protecting the fire side with more adhesive but haven’t seen damage to it yet because of the tough construction.
Protecting the fire side of a baffle is a good idea.
I used a single coat of wood glue on my old Centurion.
After 15 BP launches the low side of the baffle was in great shape
and the plate was .050" thick cardstock.

 

Joshua Smith

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Protecting the fire side of a baffle is a good idea.
I used a single coat of wood glue on my old Centurion.
After 15 BP launches the low side of the baffle was in great shape
and the plate was .050" thick cardstock.

That's a awesome idea and writeup @hcmbanjo ! Out of curiosity, did you generally fly with the baffle only, or did you put some wadding between the baffle and chute? How did your chutes hold up? Sounds like you were able salvage them so they must have held up well.
 

rklapp

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Protecting the fire side of a baffle is a good idea.
I used a single coat of wood glue on my old Centurion.
After 15 BP launches the low side of the baffle was in great shape
and the plate was .050" thick cardstock.

I can definitely see using a coat of glue on the cardstock. The included baffle in the AMRAAM is quite aways from the MM tube so should be fine. The Qualman baffles are a different breed. I should use more thin CA to soak into the fire side wood.
 

hcmbanjo

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That's a awesome idea and writeup @hcmbanjo ! Out of curiosity, did you generally fly with the baffle only, or did you put some wadding between the baffle and chute? How did your chutes hold up? Sounds like you were able salvage them so they must have held up well.
I usually used one sheet of Estes style wadding like a "peel-away" wrap on the bottom 2/3rds of the packed parachute.
The original Centurion instructions are shown below -
The Centuri Centurion was one of the first model rockets to incorporate a "plate" style baffle.

Baffle .jpg
 

Tractionengines

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Since this is the Recovery forum...here is a mockup of loading the recovery for this rocket. NOT loading for an actual flight, but just for show. Note: since I am pushing close to the 1500 gram class 1 limit; this is kind of heavy-duty comparatively.
From MMT forward. (2) 10-32 u-bolts from cable clamps. 1/8" tubular-kevlar (950#) that extends 30" past the end of airframe. With 6 inches of dual wall hi-temp heatshrink as protection over kevlar at MMT, 2" at end of airframe, and about an inch to form a loop at the end (without tying a overhand knot). Then a blanket (should be next size bigger). Then 15ft of 3/8" nylon (900#) to a swivel and quicklink. Also on the quicklink is a swivel to a 4ft Rocketman parachute, and ~18in length of cord to the nosecone (1/8" kevlar only because I had it laying around.) The taped groups for real flight, would us varying number of wraps, and varying layers of tape.
(Options: If I go big and put in a H or I205 motor and go to a HPR field; I can easily swap in a nosecone I have with a Eggfinder tracker. I can fit a JLCR. I can change to 3ft parachute to get down faster. Etc...)
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Mike
 
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