To flange or not to flange, that is the question!

[PiperCPO]

Hi all, Happy New Year!

"Santa" was good to me this year! My wife handed me a box Christmas morning that I was not expecting until a few days after Christmas. Inside was a Binder Excel DD, Mike was able to get it out in time (he was in the middle of some terrible weather) to arrive Christmas Eve, and my wife got to it when they delivered it and hid it before I got home. I had been doing some planning for this build for a few weeks and Mike was kind enough to send me a set of new instructions he has been working on since changing the kit. I have read reviews of the kit and packing and I can say I am impressed with the quality and care he takes with packing the kit! A+++ is all I can say, this will not be the only Binder kit I will invest in.

Now the planning is in earnest, though I will not be able to build for a couple months. A stipulation that the "Boss" has imposed on me! I am trying to decide whether to go with the supplied motor retainer or install a Aero Pack flanged 54mm retainer or a standard Aero Pack retainer. I am wondering what most have done with their Excels and the pros and cons of going with the flanged retainer (other than not needing a screw driver). I was hoping Aero Pack would have instructions available online but, no joy. Does anyone have a scan of the instructions for the flanged 54mm retainer that I can look at? And, if I go with the flanged retainer any advice on getting the threaded inserts in straight.

Thanks for any opinions info and advice in advance!

 

[Nytrunner]

I think an advantage of the flanged retainer (vs bonded) is that you can switch it out between rockets. Maybe save some money and keep the 'boss' happy.

For a multi-bolt pattern, dry fit it on your motor tube and clamp the centering ring to it just like you'd bond it together.
Drill one hole, place its insert, and bolt on the flange. Then you can drill the rest right to the pattern.

 

[rharshberger]

I think an advantage of the flanged retainer (vs bonded) is that you can switch it out between rockets. Maybe save some money and keep the 'boss' happy.

For a multi-bolt pattern, dry fit it on your motor tube and clamp the centering ring to it just like you'd bond it together.
Drill one hole, place its insert, and bolt on the flange. Then you can drill the rest right to the pattern.

You can also send an email to Aeropack and they will email you a pattern so you can drill the fasteners without having the retainer in hand, which is how I did it for my L3 project.

 

[fyrfytr310]

I have marked the holes by simply placing the retainer on the CR.

My preference is the have Mike Fisher make pre drilled thrust plates though

 

[Lowpuller]

How do you attach the thrust plate?

 

[jeff2space]

How do you attach the thrust plate?

Thrust plate screws onto aft centering ring. I like using wood CR for this.

 

[jrkennedy2]

Nylon nuts might make it hard to remove later on. I didn't think about that till later on... :bangpan:

98mm L3 early stuff:

 

[fyrfytr310]

Thrust plate screws onto aft centering ring. I like using wood CR for this.

This.

 

[Lowpuller]

Sorry but I'm confused.

Do you screw the thrust plate to the centering ring, and then screw the retainer to the thrust plate???

Why not just attach the retainer to the centering ring?

 

[PiperCPO]

You can also send an email to Aeropack and they will email you a pattern so you can drill the fasteners without having the retainer in hand, which is how I did it for my L3 project.

Thanks for that tidbit I will email them about it. I have not procured the retainer yet, but will soon. For me drilling from a pattern is still a little premature, I have borrowed an extra Loki 54mm casing from a friend, so that I can make sure that the retainer is centered before I mark and drill.

 

[rharshberger]

Thanks for that tidbit I will email them about it. I have not procured the retainer yet, but will soon. For me drilling from a pattern is still a little premature, I have borrowed an extra Loki 54mm casing from a friend, so that I can make sure that the retainer is centered before I mark and drill.

I did the same thing, eventually I will acquire the Aeropack 98mm flanged retainer for my Cherokee-D upscale, but it was easier to install the inserts before the build got to far along. Smart move using a casing to center for drilling.

 

[PiperCPO]

On the Binder Excel and Excel DD (I assume like most if not all of the Binder kits), the aft CR is butted up to and bonded to another centering ring on the motor tube that is just slightly larger and lines up with the OD of the body tube.



This creates a wood "thrust plate". This is secured flush with the motor tube and the retainer is attached to the assembly. The thickness of the assembly allows you to drill and put in the inserts to hold the retainer.



I hope this clears it up.

 

[jeff2space]

Sorry but I'm confused.

Do you screw the thrust plate to the centering ring, and then screw the retainer to the thrust plate???

Why not just attach the retainer to the centering ring?

You can attach retainer to the centering ring. Then forces from motor transfer to retainer transfers to centering ring, transfers to airframe. So you need a good bond between centering ring and airframe.

With a thrust plate forces from motor transfers to retainer transfers to thrust plate, transfers to airframe (thrust plate attaches to centering ring but also sits against bottom edge of airframe - that's were the forces are, not on centering ring).

If you build right there is no need for thrust plate. I use them when it makes it easier to attach flanged retainers. A 75mm motor in a 4" airframe doesn't give a lot of centering ring to attach to.

 

[Lowpuller]

Thank you for the explanation. So the OD of the thrust ring matches the OD of the body tube, now it makes since.