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Aeropack Adapters: Can you stack them?

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Kruegon

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I'm looking at my big 2017 project. Possibly 2018 depending on what I find out and decide to do.

The basic idea is a FG 4" scale missile. Something longer like a HARM, AMRAAM, AIM-9, or AIM-7. I want to make this a serious performer. I'm thinking 4" FG with a 75mm MMT. My first look at sims is showing this thing to be light enough for 38mm motors. Only J motors, but still. Obviously it'll be L capable also And technically M as well, but we aren't going there yet.

So I'm going to need to be able to adapt down. Has anyone ever tried stacking Aeropack adapters to adapt down twice? Will it work?
 

jimzcatz

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Loc has a paper 75 /38 adapter if you want to go that way, but yea, what Al said.
 

Bat-mite

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Never assume! :wink: But, yes. They fit together like spoons.
 

Kruegon

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Thanks guys. Time to look at all the cool options I can generate.
 

emckee

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I've got a set of adapters, from 98mm down to 29mm, and while I can see stacking the aeropack adapters from 54 down to 29, or even possibly 98 down to 54, I think you may run into a challenge when you go from 75 down to 38.

The reason here is that the form of the adapters changes when you compare the 98-75 and 75-54 vs the 54-38 or 38-29. The larger adapters are simply a set of rings that you place over/around a given case (see this link, towards the bottom of the page for pictures). the lower rings are stepped such that they nest into the mouth of your MMT, or eachother (no issue there). The upper portion of the adapter is a ring which you tighten over the upper portion of the case. You could conceivably tighten the upper ring of a 98-75 adapter over the ring of a 75-54 adapter - I haven't tried this, but it seems like it should work).

However, for the 54-38 and below, you're looking at a tube with flanges at the top and bottom. the lower flange should nest well with larger adapter sizes, so no issue there. But the upper flange is relatively thin, from what I recall. i.e. perhaps 0.05" thick. As such, I expect it would be challenging to tighten the upper ring of a larger adapter securely around the flange of a smaller adapter. It could technically be done, but I'd be cautious about how secure those rings actually would be.

If anyone has flown using adapters from 75 down to 38, I'd be curious to hear about your practical experience. I expect it would be easier to use some sort of paper adapter, such as what Jim mentioned from LOC.

My :2:
 

Kruegon

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Well crap. That could be an issue. I've never used a 75-54 adapter.
 

bsrocketman

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I have stacked the adapters from 75mm down to 38mm successfully. I actually did this for my L2. Loc Big Nuke(75mm motor tube) adapted down to a 38mm J570. As emckee stated, the 54-38 adapter is a tube style. On my version, there are two flanges on the forward portion. While both flanges are relatively thin, the 75mm forward ring fits perfectly over them They give more than enough support to tighten the 75mm ring onto without fear of skewing. I can post pictures if you would like.
 

crossfire

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I think someone at the Bong launch today stacked the retainers with no problems.
 

Kruegon

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I have stacked the adapters from 75mm down to 38mm successfully. I actually did this for my L2. Loc Big Nuke(75mm motor tube) adapted down to a 38mm J570. As emckee stated, the 54-38 adapter is a tube style. On my version, there are two flanges on the forward portion. While both flanges are relatively thin, the 75mm forward ring fits perfectly over them They give more than enough support to tighten the 75mm ring onto without fear of skewing. I can post pictures if you would like.
Pictures. Yes please. I'll check my 54mm adapter tonight to see if it has one or two forward flanges. I seem to recall that it has two but not certain without checking it.
 

Charles_McG

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I think someone at the Bong launch today stacked the retainers with no problems.
That might have been me, if you witnessed my pick-up from Pusher Tim. I got a 24-29mm adapter to go in my 29-38mm adapter. Didn't fly the stack that day.
 
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