Aerotech Arreaux Fin "Upgrade"

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Theory

Theory

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Getting ready to pull the trigger on an Aerotech Arreaux. I have some history with this kit as it was the first kit I built that was designed for composite motors. This was back in the mid 90's and as I get back into the swing of things I figured why not go back to the tried and true.

I am really excited about the CTI motors that were not available when I flew in the past (G126 and G80 Skid especially) and with the advent of the JLCR, using small Aerotech H motors in this thing is a real possibility. From what I recall, the airframe shouldn't have an issues holding up to these motors, so hopefully I'm good to go there.

My question is around the fins. I am toying with the idea of replacing the plastic fins with glassed plywood. My reasoning is two fold:

First, glassed wood is crazy strong and will be able to take anything these motors can dish out.

Second, I will achieve a better fit and finish over the stock plastic. I am not really a fan of the way the plastic fins "mate" to the airframe as there is a substantial gap that is tricky to deal with. Using glassed plywood will allow me to pull proper fillets and using the "double butter" method, I can ensure that they are adhered well to the motor mount.

thoughts?
 
I'm sure this will work all right, although you may not like the stock fiber centering rings, you could just get replacement plywood centering rings. But by the time you do this, you won't be using a lot of the kit. FWIW, I've flown my stock Arreaux on G138s and it's been fine.
 
I've flown my Arreaux with stock fins (epoxied in place) on I200s with no problem. About Mach .9 with dual deploy. It gets a little squirrely under thrust, so I have not tried a bigger motor.
 
Theory said:
Getting ready to pull the trigger on an Aerotech Arreaux. I have some history with this kit as it was the first kit I built that was designed for composite motors. This was back in the mid 90's and as I get back into the swing of things I figured why not go back to the tried and true.

I am really excited about the CTI motors that were not available when I flew in the past (G126 and G80 Skid especially) and with the advent of the JLCR, using small Aerotech H motors in this thing is a real possibility. From what I recall, the airframe shouldn't have an issues holding up to these motors, so hopefully I'm good to go there.

My question is around the fins. I am toying with the idea of replacing the plastic fins with glassed plywood. My reasoning is two fold:

First, glassed wood is crazy strong and will be able to take anything these motors can dish out.

Second, I will achieve a better fit and finish over the stock plastic. I am not really a fan of the way the plastic fins "mate" to the airframe as there is a substantial gap that is tricky to deal with. Using glassed plywood will allow me to pull proper fillets and using the "double butter" method, I can ensure that they are adhered well to the motor mount.

thoughts?
Click to expand...

Like you, the Arreaux was my first rocket to ever fly composite motors with. I built that rocket in 1997, and she is still going... original fins and all. If I were to ever build another Arreaux, and replace the fins with glass covered ply, it would be because I upscaled the rocket to 4" dia. As long as you do not plow the rocket into Mother Earth, the plastic fins will out last the rocket.
 
I agree the plastic fins will be fine on any 29mm motor you can fit in there. The weakness in the material is landing in cold weather, they can get quite brittle, but really only an issue with swept back fins like the Initiator.
 
To tie this one off, the kit is on its way from Sirius rocketry. The plan is to keep the factory fins, but fill the gap between the airframe and fin with thick CA. Figured this would adhere well and also would be easy to inject into the small void without investing in epoxy syringes.

Also I understand that the kit now comes with a screw on motor retainer and rail guides - I call that a win win!
 
Love the Arreaux. It was my first MPR back into the hobby and I still fly it. She must have well over 50-100 launches on it at this stage and still going strong. BTW I use a JLCR in mine.

I made a few changes that I recommend but fins were not one of them. I would use an anti zipper design and epoxy a coupler in the booster instead of the payload tube. Don't use the rod lugs and instead use rail buttons or something else for a rail. Forget the motor clip and use a retainer and if you want the bigger motors then you will have to leave out the stock baffle.
 
Theory said:
To tie this one off, the kit is on its way from Sirius rocketry. The plan is to keep the factory fins, but fill the gap between the airframe and fin with thick CA. Figured this would adhere well and also would be easy to inject into the small void without investing in epoxy syringes.

Also I understand that the kit now comes with a screw on motor retainer and rail guides - I call that a win win!
Click to expand...
Good choice! Yes, you can choose to use either the square launch lugs or conformal rail guides to glue into the slotted tube. And the AT fin can and plastic fins are its' strongest selling point. Everything is locked together, very solid. And I had some concerns about the use of CA, but read this thread on my Aerotech G Force build (posts #3 & 4):https://www.rocketryforum.com/threads/aerotech-g-force-a-quick-build-thread.146758/
The metal screw on retainer is a plus, as well as the "Labyrinth" cooling system mesh. Just be sure to push hard and lock those fins down into the slots. That will minimize any gaps with the body tube. Love those Aerotech kits! I have a few. Happy flying!
 
If you decide to use the mesh and baffle, don’t fly RMS-Plus motors with the large plastic ejection cap, use masking tape. :rolleyes:
 
kuririn said:
you can choose to use either the square launch lugs
Click to expand...

Keep in mind that when it comes to these larger MPRs and launch lugs that some clubs will not allow you to launch from the rods due to the increased potential of rod whip. I launch with both URRG and MARS and both clubs require the use of a rail with this size rocket.

kuririn said:
as well as the "Labyrinth" cooling system mesh.
Click to expand...

I do like the cooling mesh and have it still in one of my Arreauxs, however using it per stock will limit the motor length. This is only an issue if you are really going for it. Otherwise you can create a removable baffle/cooling mesh anchor point higher up in the tube.

The benefit of having it removable will be easier maintenance as the cooling mesh rusts with time and usage, and it also gets plugged up with debris. On my Arreaux that still has the stock cooling mesh I use one of those flexible three claw grabber thingies to remove replace and or clean the mesh.

Here is the claw thingy from Home Depot https://www.homedepot.com/p/VIM-Tools-Flexible-Claw-Type-Pickup-Tool-VIMFC24/207131822
 
Theory said:
To tie this one off, the kit is on its way from Sirius rocketry. The plan is to keep the factory fins, but fill the gap between the airframe and fin with thick CA. Figured this would adhere well and also would be easy to inject into the small void without investing in epoxy syringes.

Also I understand that the kit now comes with a screw on motor retainer and rail guides - I call that a win win!
Click to expand...

The retainer upgrade is a really nice touch from Aerotech. My daughter has the Aerotech Mirage, and it to came with the upgrades, they are very nice!
 
DRAGON64 said:
The retainer upgrade is a really nice touch from Aerotech. My daughter has the Aerotech Mirage, and it to came with the upgrades, they are very nice!
Click to expand...

not sure that you would know the answer to this, but is the Aerpoack 24/29 adapter compatible with the Aerotech 29mm retainer? Not sure that your daughter fly a ton of 24mm in the Mirage (perhaps some of the big CTI 6 grains would be cool though), but I am really excited about the 24/60 F51 and F63.
 
I do not own the adapter system so I cannot answer that, but as I remember it, my Arreaux came with a kraft tube motor 24mm adapter as part of the kit. Of course this was 1997 and a lot has changed.
 
So I just found this on the Apogee website for their listing of the Arreaux; looks as though they recommend the Aeropec adapter for use with 24mm motors (see about halfway down the page):

https://www.apogeerockets.com/Rocke...reaux?zenid=49q118rb2cp653iecme0q5mr77#motors

This making me want to buy another Arreaux just for the new features and possibilities that I did not originally build into mi 22-years ago...
 
Theory said:
not sure that you would know the answer to this, but is the Aerpoack 24/29 adapter compatible with the Aerotech 29mm retainer? Not sure that your daughter fly a ton of 24mm in the Mirage (perhaps some of the big CTI 6 grains would be cool though), but I am really excited about the 24/60 F51 and F63.
Click to expand...
I use the Estes 29/24 orange plastic adapter in mine (with the old spring style retainer). Works great, and it is inexpensive.
 
ooooooooooooo, I am digging that Mr. Rocket. Dual functionality FTW!!!

Question, did you epoxy the button in addition to the screw, or is the screw the only mechanism securing the button to the top of the lug?
 
I have built two Arreaux rockets and love them. Made the most recent one bone stock, except for leaving out the mesh baffle. Both have flown on dozens of G motors without a problem--great flying rockets. Simple is good.
 
Lots of flights on this one. Replaced the lugs with mini rail buttons. Used 30 minute BSI epoxy for the build. The fins were a big attraction for my purchasing the kit. They look great and are a no brainier to get a perfect finish.

IMG_5752.JPG
 
Theory said:
ooooooooooooo, I am digging that Mr. Rocket. Dual functionality FTW!!!

Question, did you epoxy the button in addition to the screw, or is the screw the only mechanism securing the button to the top of the lug?
Click to expand...

Screw only. I wanted it to be removable just in case I still wanted to use a 1/4" rod.
 

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