MAC Performance 3 inch Black Fly build.

Discussion in 'High Power Rocketry (HPR)' started by wij, Aug 23, 2019.

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  1. Aug 23, 2019 #1

    wij

    wij

    wij

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    Started building the Black fly a few weeks ago and am finally getting around to showing the build! To me, this is one of the coolest looking rockets out there.I have been wanting one for a while and after getting my L1 this summer with my Madcow Sport X , I figured this kit will build a little heavier than my Sport x and would be a good rocket to try out some I motors.

    I have never worked with the canvas phenolic airframes/fins before and so far I am really liking how sturdy and durable it is! I am planning to set this rocket up with Dual deploy in the HED configuration ( Main in the nc).
    Open to any suggestions and tips on the build. One thing I noticed immediately with this kit was the quality of the components! Everything is strong and has an amazing fit! The fins are so cool looking I don't want to cover them with paint lol. I set out all the parts and got right along with the build.

    So far I have assembled the motor mount and installed the pin to anchor the kevlar into the fwd centering ring. I left the rear CR off so I could add internal fillets. The mmt sticks out a good bit to leave room to attach the tailcone.

    After that I added fillets fwd and aft of the forward centering ring.
     

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    Last edited: Aug 23, 2019
  2. Aug 23, 2019 #2

    wij

    wij

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    Next up were the fins, I spent a few mins with 60 grit sandpaper roughing up all the fin tabs and areas where epoxy will adhere. The fit of these fins were very tight but just enough room to get them seated. They were aligned perfectly straight from the start! I used a slow cure bob smith epoxy for the fins, fillets and everything else on this kit as well. after they were tacked onto the motor mount I spent the next day or so doing all the Internal/external fillets.
     

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  3. Aug 23, 2019 #3

    spigalau

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  4. Aug 25, 2019 #4

    wij

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  5. Aug 25, 2019 #5

    wij

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    Next up was the tail cone. I sanded the whole tail cone with 150 grit and then filled any remaining gaps. Gave it a few coats of fluorescent orange followed by a gloss clear. Before installing the tail cone permanently I mounted the rail guides and coated the flange nuts with a layer of epoxy.
    After those cured it was a very simple installation of the tail cone and I like how it serves as the rear centering ring as well. Scuffed all surfaces and bonded them with epoxy. Seems very stout when mounted and will be able to take a good hit if something were to make for a non ideal descent. Last thing I did was jb-weld the aeropack 38mm retainer to the mmt and set the aft section of the rocket aside to cure overnight.
     

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  6. Aug 25, 2019 #6

    mpitfield

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    Now that is a good one!

    I like the build so far, great attention to detail!

    The best advice I can give, when it comes to the BF, is to make sure that you run simulations. The BF tends to be inherently unstable and requires some nose weight. One option that helps to offset this is to opt for the Wildman FW/FG nosecone option; it adds some mass where it is needed the most.

    I like to add removable lead lose weight, that I mould to the shape of the nosecone. I do this by mixing up some lead shot with epoxy, ensuring that the nosecone tip washer is in place, I pour it into some double wrapped saran wrap and drop it in. When it settles and cures, it will roughly be the shape of the nosecone. I then grind the top and bottom flat and drill a .25 hole down the center. Keep in mind that you will be removing 10-20% of the mass when drilling and shaping the slug, so make sure you mix up more than you need. It is always easy to grind a bit off to get down to your target weight.

    To fasten it to the nosecone, I use either an eyebolt or threaded rod, depending on your recovery config, and slide the weight on the screw.

    I like the idea of having a few weight options as it allows me to load up if required and remove it not. I tend to target a cal of 1.5 with my motor choices. Just make sure that if you do this that you double wrap the bundle, or even triple wrap it. I have messed this up on two nosecones, where some of the epoxy seeped out and I ended up with a permanent solution.

    Good luck on the build and I am looking forward to seeing some finished pics of her leaving the pad.
     
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  7. Aug 25, 2019 #7

    wij

    wij

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    Thanks for all that info mike! also thanks for the awesome build log you have on the BF. I have been referring to your builds as i'm going along and it is answering a lot of my questions.

    So for now.. I ordered this kit with the normal plastic nosecone and I most likely will be switching to the FWFG wildman NC here in the near future!

    I opted to house my main chute in the nosecone to help with nose weight and achieve correct cg.

    After washing and prepping the plastic nc I cut off the bottom and dropped about 2 oz of weight/epoxy mixture into the nose followed by my eyebolt. after securing the eyebolt I threaded some 1/8 inch all-thread through the (uncured) epoxy to secure it in place. Set that to dry overnight and it is now a very solid anchor for the shockcord.

    In addition to my avbay I am adding a short 5" section of airframe tube that will be secured to the fwd section of the av bay with 3 removable screws to give a little more room for the burrito wrapped main chute lol. This short length of airframe will also push my cg a bit more forward. This brings the total length of the rocket to 45.8 inches.


    The last modification to my plastic nosecone was the addition of shear plates for the 2-56 shear pins that will keep the nc attached to the upper payload section. For this I sanded out some patches on the inside of the payload section and the outside of the nc shoulder. I used some thin brass sheet epoxied into these divets and then drilled them out to accept the 2-56 nylon screws
     

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  8. Aug 25, 2019 #8

    wij

    wij

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    Heres a quick overview of my avbay setup I made from parts I had laying around. Very basic to get the job done. For electronics I will be using a Eggtimer Quark running on a 1s lipo. I have built 2 of these altimeters now and I really enjoy the simplicity of it for the type of flying I do. I used a 6 inch section of coupler with a 1 inch switch-band, then the bulkheads are made of a coupler bulkhead and a tube bulkhead epoxied to each other. This makes for a clean fitment when assembled. It is held together by 2 sections of 3/16 inch all-thread. For charge cups I used 1/2 copper pipe caps. They hold almost 2 g of bp which should be plenty for this size of rocket. Will know more on that when I start doing ground tests.
     

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  9. Aug 25, 2019 #9

    wij

    wij

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    Here is the finished avbay and 5" payload section fitted on the airframe. The switch-band and payload section are thick wall cardboard tubing wrapped with 2 layers of FG to match OD of the canvas phenolic airframe. Also added a pic of the whole rocket assembled to show the shape, and im digging it! No idea what im going to do for colors yet but man I love how this rocket looks!!!! Recovery components up next!!
     

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    Last edited: Aug 25, 2019

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