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  1. #1
    Join Date
    20th February 2009
    Location
    Cayuga, Indiana
    Posts
    12,737

    MAC Performance Rocketry Scorpion Review

    Please don't misconstrue this posting as build thread. I would categorize it as a review. I may be a little late to the party, but I wanted to give my thoughts and observations on a fairly new vendor (in business for ~10 mos.), MAC Performance Rocketry, doing so through comments on a kit I am in the process of completing. I'll be covering six areas: First Impressions, Materials, Kit Design, Anomalies/Exceptions, Performance and Price/Offerings.

    I purchased the 3” dia. dual-deploy Scorpion sometime during the Black Friday week. Mike Crupe the owner had provided a 10% discount. Given I was thinking about acquiring one of his kits anyway, I decided to move ahead. I received the shipment within a few days, which was quite a bit faster than I expected given typical Thanksgiving sale week volume delays.

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    Most probably know, but the differentiator for the MAC Performance line is that they have committed to a new (well actually old, but new to rocketry I believe) material called canvas phenolic. This material utilizes canvas or simply a thick cotton fabric rolled longitudinally in sheets to make a tube. This material is also layered horizontally to make fins. In either case the matrix is infused with phenolic resin, pressed and, I believe, heat cured to achieve a solid, stiff finished product. Apparently this is one of the wide breadth of materials used for military applications as, in doing research, I saw more than one MIL standard applied a few variations of canvas phenolic materials.

    First Impressions – In unboxing the kit a number of things “hit me.” First and foremost was Mike’s method of packing his kits. Pulling it out of the box amazingly the kit, to a great extent, is assembled for you. What I mean is that all the rings, bulkheads, etc. are on the tubes and in the right place—even to the extent that the forward ring for the MMT was spaced just right for fin placement. Same with the avionics bay and the optional nose cone compartment I ordered.

    The second related impression was the amazing accuracy of the CNC cuts on the kit. The reason the kit could be shipped “assembled” is because the parts fit perfectly tight and square. So what does an experienced rocketeer do? Immediately I dig out the fins and see if they have the same accuracy on the fin slots. And wow, amazingly they did! Both length and width fit perfectly. Tight yes, but that eliminates any gaps when filleting and there is absolutely no need to do any sanding/adjusting. Very nice! I am no expert, but I would probably attribute this at least partially to the material being used, canvas phenolic. Canvas phenolic seems almost “cast” into place during the manufacturing process. Compare this to a filament wound tube, which is produced with tension on the individual strands around a mandrel. When this tube is cut laterally, the “pull” of the strands tend to close those gaps shut and it becomes tough to get the right width dimension on the fin slots.

    Materials – Next in sequence I began to examine the materials. The tubing has a matte, almost suede feel. To the touch it almost feels like a freshly sprayed primer-filler coat. And in mentioning paint coats, that is another advantage of the material—NO SPIRALS TO FILL! The other distinct component material is the fins (and av-sled), which are also made with canvas phenolic but finished in a much different way. The outside layers are glossy and clearly made intentionally with a flat, smooth press after resin penetration. If I wasn’t so sloppy in my build and get epoxy drips and smudges everywhere, I’m sure the fins could be directly shot with primer and paint just like fiberglass.

    Looking at the fins/boards a bit more closely, it hit me… The brown color reminds me of old circuit boards we used to use at AT&T/Western Electric back in the 80’s, in fact, it could very well be the same material process, which is fine, as those circuit boards were bulletproof! So much so, I did some “Google research” and see a prime canvas phenolic application is for machine gearing and pulleys. Apparently in many applications it has superior wear characteristics not exuding shavings like metal materials can. I tell you if it is used for gears, it is probably more than tough enough for our rocketry applications.

    Kit Design – There are a few things about the kit design that were slightly different, most of which I welcomed and liked. Given that the kit is already built, you can’t really see the first feature, but it is the centering rings. The kit is designed with three different size and design in its centering rings. This completely makes sense. The forward CR is thicker and designed to withstand recovery stresses. The middle centering ring is thin and just provided as a reference/attach point for the fins. Lastly, the aft ring is again thicker and actually designed as a thrust plate. And, of course conveniently, the thicker fore and aft CRs, it makes it easy to get super secure attachment points for your rail buttons.

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    The motor mount tube was far longer than required. I really like this feature and sadly it is lacking on most kit shipments. Why? Well beyond my personal feeling of security having a marginally longer motor mount, there are many rockets I like to modify with tail cones and such. With most designs the motor mount is only long enough to catch the forward edge of the fin, so you have to special order or get some other tube to add a tail cone or, in some cases, even to just mount a retainer. Lastly, again with a longer MMT you have a convenient place to securely mount a rail button without it protruding back into the drogue compartment.

    The avionics bay was of clean and simple design. I really like the rounded standoffs. The av-board provided was a bit shorter than I would have built, but will work perfectly for my intended application, a MARSA54L as this rocket will be pressed into service at times to provide research motor performance measures/feedback.

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    An option I ordered was the nose cone compartment kit. It is designed to fit either a 3” or 4” 5:1 Pinnacle nose cone and can be optionally either a 38mm or 54mm compartment size. The length of the compartment is right at 6” and has more than enough room for any added tracking or measuring devices you might want to mount. I installed this using Loctite Plastic Epoxy where all pieces touched plastic and it seems “solid as a rock.” This was one place where the written instructions were a little unclear for me, but I believe they are completely correct, I’m just a more visual person and sometimes have a hard time “digesting” written references (especially after midnight sitting in a hotel room after a long work day).

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    The final feature on the kit I would point out is one I didn’t end up using, but seems like a nice feature. Mike provides a fin can harness with pre-sewn loops on each end and attached through a slot in the forward CR held in place with a hardened metal pin. I decided to instead install a ¼” forged eyebolt, but would have had no qualms in using this attachment. If utilizing motor eject though, I would suggest adding a Kevlar sleeve for longer-term protection.

    Anomalies/Exceptions – First, not all kits are perfect, although this one is pretty close. The only somewhat interesting issue that came up relates to my OCD tendency to get perfect seams on all my tubing. I go to pains to make sure these always line up and are a square as possible. I will say that the MAC Performance kits produced by Mike are about as perfect as I’ve seen, although you will always be able to find the cut end (versus the factory produced) of the tubing. For the payload tube this was simple. I positioned the cut end toward the nose cone and then filed the slight deviation to get as clean a seam line as possible. On moving down to the dual seam of the av-bay switch band (BTW, I often don’t install a switch band just to reduce seams, but in this case, I did install it) I found it a bit tougher to get right. This is not at all because of Mike’s cuts as they were almost perfect and I was able to rotate and file to get it very, very close. The deviation actually came in the way the tube is manufactured. Until getting to this point I had not noticed that on each tube there is a final small “bulge” that arises from that last overlap of the canvas wrap in the manufacturing process. So when attempting to align all three pieces of tubing and get the seams perfect, it proved impossible (at least for me in the time I had available) to also align the “bulges” in the material. Although I have it pictured below, believe me this is a small thing and will only require a bit of sanding to adjust. I just find it a bit interesting that it arose to bother my OCD behavior.

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    Performance – This part is a work in progress (as the rocket isn’t completely built yet), but I have finished basic Rocksim modifications and simulations. In doing so I also did a FinSim evaluation of the flutter characteristics. Given that I only have a 38mm motor in this rocket, I’m not pushing performance to a great extent, so there are really no worries here. I did find it interesting, in looking at the physical parameters, that although the canvas phenolic seems stiff/tough, there is, at least in the tubing some slight flex. This flex is born out in the physical parameters where the flexural strength/bending yield (and related modulus) is about 1/3rd that of a G10 equivalent. This will lead to a tendency to flutter when stressed, but saying that, in taking a step back, I don’t know if that would always be a problem. The reason I say that is that the matrix in this layup is basically cloth fabric, a fairly supple and forgiving material. Of course, in this application it becomes stiffer due to the phenolic resin, but in contrast to the much stiffer filament material in fiberglass, which tends to exhibit micro-fractures during flutter, the cotton material may be immune to this micro-fracturing. Maybe it’s more like the Boeing wings that tend to “flap” by design versus the Airbus wings that seem to be of stiffer design. Needless to say, more research must be done in this area.

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    With respect to weight characteristics and their impact on performance, the canvas phenolic offering hits a mid point between the somewhat lighter paper phenolic and the heavier G12 fiberglass. Of course, cardboard airframes are still the lightest viable material appropriate for use in HPR applications.

    Pricing and Offerings – In general, I would say MAC Performance products are priced above the mid-point for most kits on the market. Given the material makeup and the kit quality, I believe this is justified. In general, the pricing is slightly lower than an equivalent fiberglass kit but a good bit higher than cardboard-based kits from Binder Design and Madcow Rocketry.

    I believe MAC Performance has some nice accessory offerings. One set of products I have already mentioned are the nose cone compartments. Other items they carry are piston assemblies, fin jigs and altimeter bay kits that can be purchased separately.

    Conclusion – I would highly recommend a kit purchase from MAC Performance Rocketry. You will be impressed with the ease of assembly, the quality materials and the industry leading kit manufacturing process. I’m looking forward to seeing more rocketeers document their builds and flights with this great new product line.

    The proceeding is an independent review. I have no association nor receive any compensation from MAC Performance Rocketry.

    Last edited by dixontj93060; 12th December 2015 at 01:23 PM.
    L3, TRA #11847
    Tripoli Indiana #132
    Tripoli Central Illinois #59
    Central Illinois Aerospace (NAR) #527
    Chicago Rocket Mafia, "Big Bucks" Dixon
    ___________________________________

    Quiet little voices creep into my head. -- We Were Promised Jetpacks

  2. #2
    Join Date
    5th December 2013
    Location
    MD
    Posts
    6,661
    I have many great flights on my Scorpion, and I agree with everything you wrote. And Mike is super easy to deal with and very customer-service oriented to boot. That's why I'm going for Level 3 on his 4" Radial Flyer.


    John S. ---- NAR #96911 ---- TRA #15253 ---- MDRA #067 ---- BARC #028
    L1, 3/15/14: Aerotech Sumo, CTI H133BS
    L2, 6/21/14: Giant Leap Vertical Assault, CTI J240RL
    L3, 3/12/16: MAC Performance Radial Flyer, CTI M1101WH
    Altitude: 13,028', L3 flight; Speed: Mach ???, L3 flight

  3. #3
    Join Date
    24th November 2012
    Location
    Valparaiso, IN
    Posts
    709
    My Scorpion has flown at least 3 times and they have all been great flights. It was a great kit, great material, and great fit!
    ~ Justin ~My thoughts are as scattered as the frozen winds of November swept across the harvested fields of my mind.
    L1: 02-17-2013; Loc Cyclotron Aerotech H180
    L2: 02-15-2014; Scratch built rocket on Cesaroni J285
    NAR# 95496 TRA# 14658 Member of Michiana Rocketry and Indiana Rocketry

  4. #4
    Join Date
    20th January 2009
    Location
    Washington State
    Posts
    83
    Very cool
    I will definitely get one of his kits

  5. #5
    Join Date
    20th February 2009
    Location
    Cayuga, Indiana
    Posts
    12,737
    I completely forgot to post pictures of my Scorpion upon completion. Here it is:

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    And love the clean aft end with functional thrust plate (I believe Binder has resurrected this practice also--maybe due to the competition , don't know?

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    Go MAC Performance!

    L3, TRA #11847
    Tripoli Indiana #132
    Tripoli Central Illinois #59
    Central Illinois Aerospace (NAR) #527
    Chicago Rocket Mafia, "Big Bucks" Dixon
    ___________________________________

    Quiet little voices creep into my head. -- We Were Promised Jetpacks

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