First time minimum diameter build.

mpitfield said:

As per jhbarr the adapter just screws into the end of the CTI charge cup. Below are pics of my 54 and 38mm adapters, which as you can see by the last pic vary in depth and the plug that fits into the hole in the base of the charge-well. I found the easiest way to screw them in was using a socket wrench with a 22mm socket, otherwise you can misalign them very easily.


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Total noob here. How is using one of those superior to just epoxying over the delay hole? Seems like it adds mass for no reason?

smugglervt said:

I was not aware that there were threads inside the CTI charge cap. I assume you must remove the BP since I don't see where there is an opening that would allow it to work with the Aeropack adapter with bypass holes for motor eject.

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The CTI well does not have threads, the threads on the Aeropack are small and sharp enough that they self-tap. You are correct you have to remove the paper/plastic cover on the BP well and dig out the BP. As far as using this with the motor eject I am not 100% sure but I think the two options are mutually exclusive for CTI. But as I said I do not know for sure as I have never tried to do it, so you should hunt around for an authoritative answer on it. I typically only comment on things I have done.

Bat-mite said:

Total noob here. How is using one of those superior to just epoxying over the delay hole? Seems like it adds mass for no reason?

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Well I did not claim it was superior, although I might argue that it provides more positive retention for the purpose of just removing the BP charge. However this is not what this was designed for. This is the motor adapter that connects your CTI motors to the MD Aeropack. What you cannot see is the threaded hole in the top of it which acts like any threaded forward closure.

Keep in mind minimum diameter builds don't require an Aero Pack retainer. Yeah, they're pretty and shiny and look great before you install them in your rocket, but a plain old plywood or G10 bulkhead and bolt or all-thread will accomplish the same thing and take up less space.

Here is a pic that might help explain. Except this is with the Loki 54mm 1200 hardware and there is an extra threaded rod to make up the difference in length from the 54-2800 case, which is where the MD retainer is installed. And there is an aluminium adapter to convert from the 1/4-20 thread on the Loki hardware to the 5/16-18, which is what the Aeropack MD retainer and adapter as well as AeroTech use in their threaded closures.

If this doe not clarify it for CTI I can mock up a 38mm Aeropack with the adapter on a CTI 38mm case and take a pic later this evening.

mpitfield said:

Here is a pic that might help explain. Except this is with the Loki 54mm 1200 hardware and there is an extra threaded rod to make up the difference in length from the 54-2800 case, which is where the MD retainer is installed. And there is an aluminium adapter to convert from the 1/4-20 thread on the Loki hardware to the 5/16-18, which is what the Aeropack MD retainer and adapter as well as AeroTech use in their threaded closures.

If this doe not clarify it for CTI I can mock up a 38mm Aeropack with the adapter on a CTI 38mm case and take a pic later this evening.

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Just looking at the pic I am realizing this is a 38mm Aeropack with the 38mm Loki hardware form one of my 38mm MD builds. Same idea, the threaded rod is there because the MD retainer was placed in the airframe for larger motor hardware. I think in this case it was sized for a 38 6XL and that is the Loki 38-740 hardware.

Motor eject is rarely an option for MD anyway... the delays are too short.

Now I get it. Thanks.

cerving said:

Motor eject is rarely an option for MD anyway... the delays are too short.

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Good point.

Awesome to see you all got the deal!

I ordered the kit also, it is shipping today.

I have a feeling a bunch of Mongooses will vanish on K motors... Never to be found again after losing GPS lock.

Andrew_ASC said:

I have a feeling a bunch of Mongooses will vanish on K motors... Never to be found again after losing GPS lock.

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You’re such a negative nook.

That Andrew, is why I will not be flying mine on a K for a loooooooooongggggg while.

I just want to break Mach1. Haven't done that yet.
We do have a 20,000' waiver at my club every month, and plenty of land for it.
Plus club policy is that we have a tracker on anything above 3,000'.
Not very often one is totally lost, but there is a big patch of trees that seems like a rocket magnet. xD

Andrew_ASC said:

I have a feeling a bunch of Mongooses will vanish on K motors... Never to be found again after losing GPS lock.

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Just properly secure an EggFinder mini or Missileworks T3 in the NC, and you will walk right up to it. I had an EFmini in the NC of my GoDevil38. Got GPS back just before approve at 16.8k. Just remember to not only secure the tracker, and battery, but also the battery wires and connectors and you will be fine.

Cl(VII) said:

Just properly secure an EggFinder mini or Missileworks T3 in the NC, and you will walk right up to it. I had an EFmini in the NC of my GoDevil38. Got GPS back just before approve at 16.8k. Just remember to not only secure the tracker, and battery, but also the battery wires and connectors and you will be fine.

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Also one habit you might want to adopt, if you use quick-links. Don't crank them down, just hand tighten them. If your rocket get's stuck in a tree, having the quick-link hand-tightened can make recovery a bit easier. 20K is a great waiver, especially if your recovery area is mostly clear except for one hungry rocket eating patch of trees. I am typically surrounded by rocket eating trees, devouring crops and thirsty streams.

mpitfield said:

Also one habit you might want to adopt, if you use quick-links. Don't crank them down, just hand tighten them.

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A year ago, I would have agreed with this. However, I have lost two rockets to quick links coming unscrewed during flight. In both cases, the quick link came off at the point where the main came out and then the fin can lawndarted. In one case, I have a video of this happening (attached), and it is obvious that the rocket spinning is the problem. I think this happens more than we realize, and in some manner, the quick link gets opened. Now, where I can, I eliminate the quick link in favor of just connecting the harness directly to the U-bolt (or whatever is the hard point). And where there are quick links, I snug them down.

https://youtu.be/exY1PtuG1j8

Jim

Some people say it defeats the purpose of quick links, but I throw a small bit around the locking portion. Never had an issue.

mpitfield said:

Here is a pic that might help explain. Except this is with the Loki 54mm 1200 hardware and there is an extra threaded rod to make up the difference in length from the 54-2800 case, which is where the MD retainer is installed. And there is an aluminium adapter to convert from the 1/4-20 thread on the Loki hardware to the 5/16-18, which is what the Aeropack MD retainer and adapter as well as AeroTech use in their threaded closures.

If this doe not clarify it for CTI I can mock up a 38mm Aeropack with the adapter on a CTI 38mm case and take a pic later this evening.

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Kit-bashing tip: Make the booster in 2 shorter parts - Fin can and a bulkhead mount/retainer. It allows the shortest allthread, and self-sizes to any case length used.

Igotnothing said:

Kit-bashing tip: Make the booster in 2 shorter parts - Fin can and a bulkhead mount/retainer. It allows the shortest allthread, and self-sizes to any case length used.

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I'm having trouble visualizing your tip. Could you elaborate?

kevinkal said:

I'm having trouble visualizing your tip. Could you elaborate?

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Same here, what I have in my head is not very practical for a MD airframe. But maybe I just lack some imagination.

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