LPR / MPR Motor Retention Comparison

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sl98

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There has been a fair amount of discussion regarding the various LPR/MPR retainers. I've taken some pictures and weights of Estes, Rocketarium and Aerotech retainers. Hopefully this will help you choose what is best for your build. First the 18mm and 24mm retainers:

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The Rocketarium 18mm weighs 3.9 grams
The Rocketarium 24mm weighs 7.6 grams
The Estes 24mm weighs 7.8 grams

Instead of measuring with calipers I've taken pictures using various Estes size body tube for reference.

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sl98

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Next is 29mm.

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The sanded Estes weighs 12.4g
The Estes weighs 13.4g
The Aerotech weighs 27.7g

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neil_w

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Is "sanded Estes" just an Estes retainer with the knurls sanded off? How come it's a different color?
 

sl98

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ImageUploadedByRocketry Forum1485114076.029242.jpg

I used a sanding disc. The cap is slightly angled so I alternated cap as I sanded. I used a wide tip Sharpie after sanding to give it a uniform color.
 

T-Rex

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I have avoided using the Estes because I felt that the cap was gaudy. I like your idea of sanding and 'painting' to give it cleaner lines. I may start using them....
 

Cabernut

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Good comparison. I've thought about sanding down the Estes retainer caps. For what it's worth, the Estes retainer caps get a little cooked from the heat. However, they are 1/4 the price vs. aluminum ones.
 

The_Lone_Beagle

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Nice, thanks for the comparison photos. The sanded Estes is a lot nicer than the regular Estes!
 

soopirV

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Good comparison. I've thought about sanding down the Estes retainer caps. For what it's worth, the Estes retainer caps get a little cooked from the heat. However, they are 1/4 the price vs. aluminum ones.
How long would you say they might last, if you had to give an estimate? What sort of motors are you running in them, the Estes S/U 29, or AT or CTI reloads?
 

sl98

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How long would you say they might last, if you had to give an estimate? What sort of motors are you running in them, the Estes S/U 29, or AT or CTI reloads?
Until you lose the rocket. I've been using the Estes retainers since they came out and other than a little soot they are fine. I've flown the 29mm up to 29/240 motors ...H250G, H180W & H97J. 24mm have flown up to 24/60 and 3G CTI.
 

Cabernut

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A couple days ago I tried the sanded retainer and it's quite easy to do even by hand. Use an x-acto to cut the majority of the ribs off, then sand. Looks great! I may do this more often! Thanks for the tip.

 
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