Any Recent Aerotech Strong Arm Builds

[JLP1]

A couple of weeks ago we were hitting several neighborhood wide garage sales when I found a box full of hobby stuff and in it I found a brand new unopened Strong Arm kit. It's the one with the updated motor retainer and the preformed strakes. I've been searching the net and most of the information I've found on the kit dates back to 2016 when they were still using the motor clip and cutting out the strakes. Has anyone built one recently? I've never worked with the fin loc system, do you still put external fillets on the body tube? The instructions are a little confusing because it looks like they didn't rewrite them to incorporate the changes they just added some inserts. Any tips or tricks would be helpful.

Thanks in advance

 

[rcktnut]

I built one years ago, use the medium vis. CA for construction and you will be fine. Disregard the old MMT instructions and use the insert instruction for the MMT. 9d7d9635-a112-4290-b75a-b8d2a3b3c77a_STRONG ARM Motor Retainer Upgrade Notice with guide.pdf (aerotech-rocketry.com)
Test fit your fins in the Fin-Loc system before gluing to make sure they snap in. I have/had 9 Aerotech kits all built stock, a few fins had to be sanded down a bit to snap into the Fin-Locs. I never applied fin fillets, they fit tight to the body tubes for the most part. I did apply a little extra CA to the fins if there was a little gap between fin and body tube and that filled the gap nicely.
I lost my Strong Arm to a power line, been thinking about getting another. It is a great looking, great flying rocket.
My Aerotech rockets all of them at least 15 years old are holding up just fine built with the CA Have fun!!

 

[tab28682]

No need for fun fillets on the Strong Arm.

Really like this kit. One of my favorite mid power rockets.

 

[AfterBurners]

you can assemble it with a medium CA, The fin lock system literally makes it a snap to assemble.

 

[AfterBurners]

I built one years ago, use the medium vis. CA for construction and you will be fine. Disregard the old MMT instructions and use the insert instruction for the MMT. 9d7d9635-a112-4290-b75a-b8d2a3b3c77a_STRONG ARM Motor Retainer Upgrade Notice with guide.pdf (aerotech-rocketry.com)
Test fit your fins in the Fin-Loc system before gluing to make sure they snap in. I have/had 9 Aerotech kits all built stock, a few fins had to be sanded down a bit to snap into the Fin-Locs. I never applied fin fillets, they fit tight to the body tubes for the most part. I did apply a little extra CA to the fins if there was a little gap between fin and body tube and that filled the gap nicely.
I lost my Strong Arm to a power line, been thinking about getting another. It is a great looking, great flying rocket.
My Aerotech rockets all of them at least 15 years old are holding up just fine built with the CA Have fun!!

I agree for sure. I think dollar for dollar they offer he best value. I have the Initiator and the Sumo (second one) I have had others that sold to interested parties.

 

[JLP1]

I'm working over the instructions now and we shall see what we shall see. I usually use CA to tack things in place. Looks like I need to order up some medium CA. Good info on not needing the fillets.....Thanks Guys

 

[KenECoyote]

As recommended above, test fit the fin locks before assembly, but critical is to do this outside of the rocket before any assembly. On my Strong Arm I ended up shaving some of the locking tabs until the fit was good to me (snaps snug, but not too hard in nor too easy out). This will spare you the panic I had when I CA'd the fins and slots in my Sumo and one wouldn't snap in (eventually it did after much feverish work yanking out and shaving down the CA covered piece).

Strong Arm is one of my favs, so great find!

 

[JLP1]

Anybody out there ever use Starbound EM-150 Medium CA? It comes with several very fine tipped applicators, and couple of extra caps. Got a 2 ounce bottle for my bonus points along with free shipping so I figure I'll use it on the Strong Arm.

 

[mikebpd221]

I'll be the cautionary tale for overbuilding the Strong Arm. I did epoxy construction with it and it was rock solid. Too much so. The fin roots were overly rigid in comparison to their material composition. Lots of fin flex with the force being concentrated at the root where it couldn't move. Two landings in a row on hard soil and I had two fins break at the root, one completely clean off . Easily repairable with a stock build, just pop out the old fin and insert a new one. That's assuming the fin even breaks as the joint could fail before the material does. But with an epoxy build, there's no easy way to cut open the fin can to get the fin root out and a replacement cant just snap in as intended. In my case, I got four beautiful flights out of her before she got grounded and cannibalized for parts.

 

[timster68]

I just picked one up off EBay. Can’t wait to put it together. I had a IQSY and I didn’t check the fin fit before I put it together - one of the fins stuck out of
the body tube about 1/16 of an inch. I’m glad I read this so I remember to check the fit before I glue it.

 

[hball55]

Only one reason for external fillets on this rocket, and that is if you are leaving out the motor block and baffle system so you can fly some H motors, which I probably wouldn’t do.

 

[hball55]

I'm working over the instructions now and we shall see what we shall see. I usually use CA to tack things in place. Looks like I need to order up some medium CA. Good info on not needing the fillets.....Thanks Guys

Always wise to dry fit parts before deciding to do something irreversible.

 

[JLP1]

Well started building the SA this last weekend. I usually start with the nosecone first to get it out of the way. Washed the cone with hot soap and water and that's when I noticed black grit embedded in the plastic. Must have been in the mold when they were being made. Cut off the plastic loop first and this left some nasty little holes in the cone so I plugged those with some rocketpoxy. Sanded the cone with 320 grit paper which got rid of most of the grit. There are two mold marks that are pretty deep so I filled those with spot putty. I noticed something about the plastic it seem to be very soft a little too much fingernail pressure and it would leave a dent I also noticed during washing that the surface plastic would come off and collect under your fingernails almost like it was real old plastic deteriorating. Anyway it cleaned up fairly good so I drilled 2 holes for the Kevlar loop and now I'll wait for the putty to dry and sanded it again with a little finer grit paper.

 

[Art Upton]

FYI I flew an IQSY Aerotech Rocket on an H motor, a smaller diameter and never had fillets on it. It didn't have the baffle taken out it was in there, the motor stuck out the back a little. Still tested Stable and flew at NSL in Alamogordo 2010 I think?

 

[Art Upton]

I've flown an Estes Partizon 2.5" rocket, no external fillets, gorilla glue fins to motor mount on I205: https://studio.youtube.com/video/G23TYUsGf5E/edit

The body tubes were not glued together either, they had masking tape on the tube couplers to keep them tight. The reason was that it had to be disassembled to ship Hold at FedEx going to the launch and ship Priority mail back home after the launch along with several other rockets I shipped out before flying to the launch. Motors bought at the launch site from Balsa Machining.

 

[JLP1]

So back working on the Strong Arm, finished the prep work on the NC, final prime coat and sanding with 1500 grit paper. Ready for first coat of gloss winter gray. Used the Bulldog Adhesion Promoter seems to be good stuff but expensive $15 a can.
Note: Use lots and lots of ventilation when using the Bulldog

 

[JLP1]

So moving along I started working on the motor mount, a couple of notes: In the revised instructions there is a new guide for the fin-lok ring placement. Use your ruler for the measurements on the tube, the 3-9/16" and 1-1/2" are correct but your guide will be off by a 1/16 (some folks might place the MT down on the guide and mark it). I don't know if it's the printer scaling or if it was drawn that way. Started cleaning up the fin-loc rings and test fitting beware they are a tight fit.

 

[Warren Baker]

I have one almost ready to fly. I need to do another clear coat over the decals. I changed the strakes a bit to make it look a little more like a Navy standard. The biggest issue I had was with static while painting.

 

[Pepe Le Pew]

Beautiful build Warren. Looks like the start of a goonie under the strongarm!

 

[Warren Baker]

Thanks! I'm playing with some strap on boosters on a Black Brant right now. I can't get a day when I can have time and weather so I just keep building more!

 

[JLP1]

So I'm back to working on the Strong Arm and I have a question or maybe just curious. The instructions say to stretch out the cooling mesh about 6" and then insert it into the motor tube and not to cement the mesh into the tube. I've never worked with this type of ejection system before so what prevents the gases from the ejection pushing the mesh up into the baffle and becoming a compacted hard block ?