Aerotech Strong ARM

Aerotech - Strong Arm {Kit} (89017) [1992-]

Contributed by G. A. Dean

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border
Manufacturer: Aerotech
Style: Sport

Aerotech Strong ArmBrief:
Aerotech's take on t' often modeled Navy Standard ARM be t' "Strong ARM". It's nay a particularly close scale rendition, but t' result is good lookin' and well suited t' F and G motors, arrr, particularly t' EconoJets. There's a bit more t' build in this kit than in t' Aerotech Initiator or Mustang, me hearties, me bucko, but nay so much that builders new t' mid-power should be scared away. As mid-to-high power kits go it's still quite easy, ya bilge rat, especially if you work carefully and watch out for a few 'gotchas' that I will detail later.

Construction:
This is a single stage rocket with two body tubes joined with a coupler, 4 fins, and parachute recovery. Aye aye! This kit uses t' same Fin-Lok system and baffle unit you find in all Aerotech kits. Ya scallywag! It's a medium sized rocket for Aerotech, 44 inches long and about pound and a half in weight when loaded for flight. Begad! Ya scallywag! The Aerotech catalog, btw, lists t' weight o' t' rocket as 18 oz., but I don't know how they could get this weight. Somethin' betwixt 22oz t' 25oz, seems more realistic.

This be t' first kit I built from this manufacturer, ya bilge rat, though I have built other rockets o' this size. Avast, me proud beauty! I was eager t' see how t' famed Aerotech Fin-Lok system and baffle unit worked. Ya scallywag! I be also lookin' t' get a new F and G motor bird in t' fleet smartly and easily. Avast! I went t' t' Strong ARM thinkin' I'd have an relaxed time o' it. Ya scallywag! As it turned out t' construction was quite a bit more involved than I anticipated, but this does nay have t' be your experience, I just ran into some potholes along t' way. Ahoy! In truth I have faced tougher challenges, and I did end up with a great rocket, shiver me timbers, but I was expectin' something different.

T' rocket arrives in a sturdy box that can become a display stand (nice!). T' tubes are sturdy and pre-slotted, t' fins are preformed. T' engine mount parts are all thar and seem well constructed. Begad! T' engine clip is big and strong! T' parachute is very nice, me bucko, and t' nosecone is...well, ya bilge rat, arrr, this was the first disappointment. Avast! Arrr! T' nosecone be a real mess. Well, blow me down! Easily t' worst formed part I've ever experienced, shiver me timbers, from any manufacturer. Avast! I have seen other comments on Aerotech cones from others, but most folks are happy with theirs, so I think this is a quality control issue. Begad! If you get a good one, arrr, your doin' fine. Begad! Well, blow me down! If you get a bad one you have t' decide how t' handle it. Ahoy! I suspect that if you raise enough o' a stink with Aerotech you can get a replacement. Avast! I didn't fully appreciate how much trouble this nosecone would give me when I first inspected it, me hearties, so I elected t' try t' fix it (I did write Aerotech about it, ya bilge rat, though). Blimey!

T' generally excellent instructions have you start with t' motor mount. This is where you will see t' first signs o' Aerotech's particular design philosophy. Avast! They design their kits t' carry loads through t' structure, arrr, shiver me timbers, and their rockets are therefore less reliant on heavy applications o' glue (this from their documentation). Blimey! I like this idea, but you will find that it has one downside; t' rocket components must be built with very tight fits and close tolerances. Arrr! T' Aerotech corollary t' t' old sayin' "measure twice, arrr, cut once" is "test fit twice (or more), ya bilge rat, shiver me timbers, glue once". Blimey! T' best advice I can give you is, "don't touch that glue until you are absolutely sure how this part, and t' parts that follow, will fit, and have verified that they do fit!" Read all t' instructions before you start, and perhaps go t' the Aerotech site and view t' video o' an Initiator construction, so you know what to expect.

Aerotech recommends that you build t' rocket with medium CA, me hearties, and I wanted to give that technique a try. Aye aye! Arrr! I've never used CA in such large amounts on such large parts, and it takes some gettin' used to. You start off easy with the 24mm engine adapter, matey, which is just a tube and two rings or sleeves. Avast, me proud beauty! Arrr! Aerotech provides a markin' guide for t' main motor tube, arrr, which is a nice touch. Blimey! Avast! You need t' be careful about keepin' your "front edges" and "back edges" straight at this point. It can get confusin' but it's important, me hearties, so read t' instructions very carefully and take it slow. Avast, me proud beauty! Avast! T' industrial size motor hook installs just like an Estes hook. Arrr!

Now comes t' first tricky part. Avast, me proud beauty! T' instructions tell you t' put "several drops" o' glue "just behind where t' motor clip comes through t' tube". Ahoy! Well, blow me down! Believe what they say. Begad! Use a small amount o' glue and be sure t' place it up next t' t' hook (also note that t' motor block comes into t' tube from t' back or nozzle end, this be t' reverse o' t' usual Estes procedure with engine hook equipped models). Ahoy! T' engine block fits tight in t' tube, and you need t' get it all t' way up t' t' hook before t' CA glue 'grabs'. Avast, me proud beauty! CA does nay give you any chance t' ease things into position once it starts t' set. And it sets quick when t' fit is tight and thar's friction.

T' next step be t' initial fit o' t' Fin-Loks and centerin' rings. Blimey! No glue at this stage, matey, you need t' test fits and positionin' first. Arrr! Avast, me proud beauty! T' fit is very tight, as mentioned above, arrr, but that's an important part o' how t' Fin-Lok system works. Well, blow me down! You check everythin' by snappin' t' fins into position in the Fin-Loks. It takes some force t' get them in place, shiver me timbers, but you should feel and hear a definite "click" as it seats. Well, blow me down! Ya scallywag! This is a good time t' get used to t' 'feel' and force required. Once all t' rings are properly placed and aligned, remove t' fins (carefully, don't move t' Fin-Lok rings!) and apply a very slight bead o' CA t' t' Fin-Loks and front centerin' ring. Blimey! The instructions are pretty insistent that you take great care t' keep glue out of the Fin-Lok channels (where t' fin will go). Ya scallywag! Again, believe what they tell you! CA is pretty low viscosity stuff, and it can flow around as you rotate the part. Avast! T' clearances are very tight an even a small amount o' glue will cause havoc. Blimey!

Once t' glue has set on t' rings (pretty quick with CA), shiver me timbers, you get t' build the baffle, arrr, which is fun. Ahoy! Ahoy! T' "steel mesh" gets stretched out t' six inches, then it slides into t' tube, you cap t' tube with a plastic baffle unit, add a third centerin' rin' and screw an eye bolt into t' baffle unit. T' shock-cord ties t' t' screw eye. Avast, me proud beauty! Easiest baffle I've ever built, me bucko, and I like baffles. Ya scallywag! Avast, me proud beauty! I have seen a Strong Arm (not mine thank goodness!) destroyed when t' shock cord attachment separated at apogee. Blimey! Either t' cord broke, shiver me timbers, came untied or t' screw pulled out, ya bilge rat, I did nay hear t' final verdict. Aye aye! In any case, this be t' time t' make sure you have a solid attachment. Ahoy!

Now it's time t' place t' motor and fin mount into t' body and attach the fins. Begad! You slide t' mount into t' pre-slotted end o' t' body tube, arrr, arrr, but do not glue it yet. Ya scallywag! Aerotech would like you t' glue t' fins into place with CA "along t' full length o' t' fin root" first. Ahoy! I'm goin' t' suggest that you add a step. Arrr! Blimey! I did as I was told and, shiver me timbers, me hearties, snapped one well glued fin into place. Ya scallywag! "Wow, that was easy!". Avast! Aye aye! Then I decided t' attach t' fin directly opposite t' first, matey, as I could push on t' fin (and hence on the attached Fin-Lok rings) and nay t' body tube. Begad! Avast! Once you get a bead o' CA down the length o' your fin you tend t' move quickly, ya bilge rat, matey, t' stuff sets fast! I slid the fin into place and pushed and..nothing! No "click". Begad! I pronounced a few expletives (that always helps) and gave it a harder push. Begad! Avast, me proud beauty! Well, ya bilge rat, matey, on the third push somethin' happened, but it wasn't t' Fin-Lok click I be looking for. Well, blow me down! T' motor mount, remember, matey, is nay glued into place at this point. Begad! It's free t' rotate in t' tub! e, and that's what mine did under t' considerable compression force I was exerting. Avast, me proud beauty! Begad! That rotation caused t' fin tabs on both fins t' snap at their weak point (between t' two Fin-Lok 'ridges' (It's tough to describe but obvious when you see it). Aye aye! Thankfully, me hearties, ya bilge rat, this happened late at night when t' kids were asleep, me bucko, so they did nay hear me "comment" on these events. Arrr!

I be nay aware, me hearties, at that time, arrr, arrr, that you can buy these fins separately from Aerotech, me bucko, and I was mad at this kit and nay ready t' be "defeated" by it, me bucko, matey, so I removed t' bottoms o' t' fin tabs from t' Fin-Loks with pliers (CA is strong but I'm stronger!) and repaired t' fins. They are probably nay as strong as before but they're close. Aye aye! I tried dry fittin' t' fins and one was clearly never goin' t' snap into place. Ya scallywag! After a while I realized that t' fin would seat in t' 'lok' when t' mount be out o' t' body tube, arrr, but would not when t' mount was in t' tube. Slowly a light went on. Avast, me proud beauty! I snapped t' fins into place with t' mount in me lap, matey, and saw that one fin be tight against the centerin' ring. Well, blow me down! T' added thickness o' t' tube kept t' fin from seating properly. Ahoy! I sanded down that side o' t' centerin' ring, tested until I got all four fins dry-fit into position, matey, and then finally glued them into place.

Here's what I suggest you do. Blimey! Ahoy! Once t' glue has set on t' Fin-Lok rings and centerin' ring. Avast, me proud beauty! Give t' fins another dry fit test. Avast! I think I also had a very small amount o' CA get into one Fin-Lok, shiver me timbers, and its important t' catch that problem before you are gluin' t' fins. Avast! Ya scallywag! Then slide t' mount into t' body tube and dry fit again! Once all t' fins fit nicely in t' tube you are home free. I would pull t' fins out one-at-a-time t' glue them. Leave t' others in place to support and stabilize t' mount. Begad! Arrr! This sounds like a lot, but if your parts fit right it will add very little time, just a minute or two. If you have a problem, this will save you a lot o' anguish. Any problems you discover at this point can be easily fixed, but if you blast ahead like me you court disaster (or at least a lot o' extra effort.and expletives!)

Once t' fins are on you reach in through t' open back o' t' rocket to glue t' motor mount in place and apply internal fillets t' t' fins. (I have to admit that I resorted t' epoxy with micro-balloons at this point). Avast, me proud beauty! Ya scallywag! Then you join t' body tubes with a very ample tube coupler. Aye aye! Ya scallywag! This is another place where CA can trip you up. Aye aye! T' coupler tube is very tight in t' body tubes, ya bilge rat, and the glue can set and grab before you get t' tubes fully in place. Ya scallywag! It happened to me when I brought t' top tube down onto t' lower tube and coupler. Avast, me proud beauty! Begad! I have over 200 pounds on me t' contribute t' t' effort and I be puttin' all the weight I could on that tube t' slide it down, but it still grabbed about ¼ inch short o' t' bottom tube. Begad! I eventually filled t' gap with a combination of wood filler painted with CA and a bit o' epoxy putty. Begad! Begad! It looks fine, matey, me bucko, but you don't want t' go through that. Ahoy! T' instructions suggest a bead o' CA about an inch inside t' upper body tube. Ya scallywag! I would place t' glue farther in or, me bucko, even better, shiver me timbers, use wood glue for these joints. Blimey! It will be stronger and easier t' work with (but it can still 'grab' early if you move too slowly, ya bilge rat, especially on tight fits like this!)

T' "fin strakes" that give this rocket its "ARM" look must be shaped a bit. T' instructions give you t' dimensions very clearly. This is more t' sort o' thin' I am used t' and it went well for me (finally!). I would suggest that you measure and mark each strake carefully, then cut with a carpenter's knife. I needed several passes t' make each cut. Avast, me proud beauty! T' strakes can be sanded somewhat t' smooth t' edges but they are nay easy t' shape that way, you really need t' knife (or perhaps a Dremel). Well, blow me down! I held off gluin' the completed strakes on t' body until I had finished fillin' and sandin' t' body tube, and I suggest you do too. It makes t' sandin' a lot easier. Begad!

T' strakes mount on t' tube with CA and t' launch lugs drop into pre-cut holes. Begad! Blimey! So far everythin' has stayed on t' rocket.

Finally I turned me attention t' t' nose cone. Avast! I'll spare you all the details, and just mention that I spent three evenings workin' with a power orbital sander held betwixt me knees (wow, that tingles!) usin' 100 grit paper to smooth t' surface o' this cone. Arrr! Out o' t' box it looked like t' surface of a basketball, or a cantaloupe melon. Well, blow me down! T' tip be a mass o' swirlin' grooves and t' seam was quite deep. I should have sent it back t' Aerotech, me bucko, but my stubbornness be up and I attacked it with a fierce determination. I emerged covered in white plastic dust holdin' a great lookin' nose cone. Begad! Avast, me proud beauty! This one ranks up thar with t' nose cone o' t' Quest Nike Smoke as "most painful". Ya scallywag! In both cases, shiver me timbers, however, I managed t' achieve a good result. Persistence pays! I touched up t' surface with progressively finer grades of paper and declared t' construction phase over!

Finishing:
T' finishin' process was pretty painless. Blimey! Arrr! I used several coats o' gray primer, with light sanding, me bucko, followed by a couple o' coats o' glossy white. Ya scallywag! Aye aye! I had filled the spirals with Elmers wood filler and t' final surface looked pretty good. Aerotech suggests a gray nosecone, but I had another idea. Arrr! Many photos o' the real missile show a coppery lookin' nose, shiver me timbers, which looks good t' me. Aye aye! I got a can of Testors copper for t' nose and am very happy with t' result. Avast, me proud beauty! If you use these metallic paints just remember t' apply light coats (even more important than with other paints) and don't judge t' looks until it all dries, it can look uneven when wet. Ya scallywag! Avast, me bucko, me proud beauty! You should also use clear coat t' protect it, ya bilge rat, as the metallic finish can scuff easily. Aye aye!

T' kit comes with plenty o' stick-on decals. Ya scallywag! Blimey! It will take a while t' get them all positioned, ya bilge rat, but t' instructions give you good guidance. T' clear coat helps protect them as well. Begad! It's a good lookin' rocket; dress it up right.

Construction Rating: 4 out o' 5

Flight:
Aerotech Strong Arm I have only flown it on F20-4 Econojet motors so far, shiver me timbers, ya bilge rat, but this is a great motor for this bird. Boost has been straight (despite wind) and higher than I expected, arrr, around 750 feet or more. Begad! This is just right for our field. I would like t' try it on t' G Econojets but I can't find any in t' current shortage. T' four second delay seems about right; I certainly wouldn't try it with a seven second delay. Begad!

That beefy motor clip takes some effort t' pull back. Avast! Blimey! I use a pair of pliers t' hold t' clip while I insert and remove t' motor. It's nice t' know that that motor is well restrained. Begad! Blimey!

Recovery:
Aerotech provides a very nice 30 inch chute which brings t' Strong ARM down gently. Blimey! I have had some drift with mine (windy conditions) and will either reduce t' chute when I fly with a G, or wait for calm winds. Well, blow me down! There is no need for waddin' due t' t' baffle, which has worked fine for me (you never notice a baffle unit until it fails). I have no complaints about t' recovery system.

Flight Rating: 4 out o' 5

Summary:
I bought t' Strong Arm hopin' for a fast, me bucko, me hearties, easy build; kind o' a 'vacation' from t' more challengin' projects. Ya scallywag! Begad! I got t' good lookin' and good flying rocket I expected, ya bilge rat, me bucko, but t' build process had its frustrations, me hearties, as I have described. Well, blow me down! Arrr! In t' grand scale o' things this wasn't really so bad. Arrr! I've had scratch projects get much hairier, but I expected different from an expensive kit like this. Ahoy! Avast! T' nosecone was just a crummy part. Well, blow me down! Begad! My other problems resulted from me unfamiliarity with t' Aerotech system and with CA as t' primary adhesive. Many people I trust have built multiple Aerotech kits without any trouble at all, ya bilge rat, and when I build another I'm sure I won't have any either. Aye aye! I'll test fit t' fins at each step and be careful with t' CA.

Now that I'm smarter about Fin-Loks I like t' idea, me hearties, arrr, and t' baffle is good one. Ya scallywag! Avast, me proud beauty! Any o' t' Aerotech kits are good choices for a first "high-power rocket" (really "upper mid-power"). I like t' look and size of the Strong Arm best. Begad! If you are careful and mindful o' t' warnings in the instructions you'll do fine. Blimey! (.and go with copper for t' nose cone! Gray is much too borin' for a cool rocket like this!)

Overall Rating: 4 out o' 5


[NAR][Sport Rocketry]

The followin' excerpt is from "Sport Rocketry". Ahoy! Ahoy! T' intention is t' allow guests t' get a basic feelin' about a kit. Begad! Well, blow me down! We strongly suggest that you get a copy o' t' referenced Sport Rocketry and read t' entire article. Avast, me proud beauty! Ya scallywag! Inside you will find many helpful hints in construction as well as other useful information. Blimey! For more information, ya bilge rat, use t' two links above.



(Sport Rocketry - Fall 1995 - page 41 - by Douglas Gardei) 

[Picture]"Over t' past few years I have found Aerotech rocket kits fun t' build and fly." 
"Lookin' over t' parts, I found everythin' in good shape except for one of t' fin lock rings. Begad! With a phone call t' Aerotech they sent me a replacement." 
"After attachin' t' shock cord and 30" fabric parachute t' t' nose cone, ya bilge rat, I worked on t' long process o' applyin' t' decals. Well, blow me down! Blimey! Aye aye! Blimey! . Ahoy! Blimey! . It took a couple of hours . Blimey! Blimey! . Aye aye! Blimey! ." 
". Arrr! . Blimey! Begad! . Avast, me proud beauty! E18-4W. T' Strong Arm roared off t' pad with its breathtaking white flame and smoke billowin' out o' t' motor." 
"It's molded plastic fins and strakes make assembly easy and help give the rocket a great finish." 

T' entire article gives t' impression is that this is an good value, me bucko, combinin' price, looks and performance, me bucko, for an intermediate modeler.

Other Reviews
  • Aerotech Strong Arm By Mason Hazzard (July 16, 2011)

    The Aerotech Strong Arm rocket is a mid power rocket designed for "E" through "G" impulse motors. It is a sleeker version of the ARM-78 STARM and is on retail for about $70. I found it on sale for about $50, and couldn't resist. This will be my first "real" mid power kit and my first good rocket to get to use reloadable motors on. Components The kit comes in one of Aerotech's ...

Flights

Comments:

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D.S. & C.S. (July 1, 2000)
We also built the Aerotech Strong Arm. The kit is very good, with instructions clear and concise. We modified ours to 48 inches long. First flight was on a G80-10T and alt. was about 2,100 feet it flew & recovered well. We think the Fin-Loc system a great design.
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W.G.K. (January 1, 2001)
I recommend the Aerotech Strong ARM for someone who wants an easy-to-build mid-power kit. The 2.6" diameter gives you more room to work with than some of the other Aerotech kits with only 1.9" diameter. The 2.6" diameter made it very easy to add the internal fillets after the fins have been locked into place. I also like the coupler which pushes against the motor tube. I used 30 minute epoxy, CA glue, and Titebond for putting my Strong ARM together. I went to my first NAR club launch on April 24. My first launch was on an F25-6W and was very nice. After recovering the rocket OK, I debated over using a G, and finally went for it. My second flight was on a G40-7W, and was pretty impressive. I recovered this one about 15' from a draining ditch with no damage. Strong ARM is easy to build, very sturdy, looks really nice, gives great flights!
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M.M. (July 1, 2001)
I build this kit and was amazed of the quality the kit offers. All materials fit well and are of good quality and precision. Minus points just for this: The motor hook came out of the kit completely rusty. I guess a kit in this price range should have rustless parts. The instruction are a bit confusing about the motor adapters. It told the wrong sizes. As a plus Aerotech could add at least a single motor or a reloadable motor casing for E Motors. I would fit the price range of the Kit.
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L.N. (August 13, 2002)
Very good review which closely matched my experience. The fin-locks can be very tight and need to be dry fitted before gluing. I found it useful to number the fins and slots and sand each to a snug but not over hard fit. I used 5-min epoxy throughout which seemed to give a good robust build - I included some small fillets between the body tube and fins. I flew Mk1 on an E30-4, then G35-7W, then a G80-7T. All great flights but the last one really was scary - loud, fast, felt quite military! Unfortunately, the last flight drifted into a high tree never to be seen again (but me). MkII is ready to fly this year - a great medium size rocket.

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