Yet another MAC Black Fly Build Thread. 4" DD L2 Cert Attempt.

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Which Altimeter would you use for L2 and why?

  • Missile Works RRC2+

  • PerfectFlite StratologgerCF


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DeepOvertone

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I decided to go ahead and post my build since I have months to work on this one. This will be my first build thread so please bear with me while I stumble along. If anyone has any tips or specific requests for photos please feel free to let me know.

On to the story of the rocket itself.... Ever since I really got started in the hobby, I've loved the MAC black fly design but I knew I wanted one larger than the standard 54mm offering. So one day I decided to contact Mike at MAC Performance and inquire about an upscale one off. He happened to have built a handful of 3" kits that weren't going to be part of his usual offering but since he had a couple left over he offered me one. I had really wanted a 4" but he said he had no plans to offer one in that size so I took him up on the 3". Fast forward a not too insignificant amount of time and I saw a forum post about him building a few 4" kits if anyone wanted any. Long story short, Mike(being the wonderful guy that he is), allowed me to return the 3" and pick up a 4" kit with all the fixins' to be a Dual Deploy Fly. He said I was the first, and to my knowledge no one else has one thats going to be set up for DD. Regardless, its been sitting against the wall while I focused on my L1 and some other fun projects.

Now I've started on her and I plan to document as I go along and attempt my L2(Do or do not, there is no try, right?). Thanks for coming on this journey with me!
 
I started on the motor mount by measuring the fitment of the forward centering ring, rear centering ring, tailcone and fins. Then I started assembly by gluing the forward centering ring on to the motor tube per the included directions. The instructions mentioned to only glue the forward end of the centering ring but I had made sure that there was space for the fins even with a filet of glue on the aft side of the forward ring.
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As you can see from the second picture, I also glued the back side of where the harness goes through the forward CR.

I had to sand the motor tube quite a bit to get the Aeropack retainer to fit on there properly. However I didn't glue it just yet.
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While the forward CR was drying, I set to work on the printed tail cone. I used some sand paper to flatten the bottom as well as removing all of the printing marks. I then used some Goof Off Pro to wipe the flattened surface. The Goof Off is mostly acetone so this melts the plastic and leaves it shiny. I'll be doing the same on the sides of the tail cone once I finish sanding it down. Its actually not too difficult to sand whatever this printed material is.
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Once the motor mount was dry, I measured the distance from the aft end of the booster tube to where I would be gluing the forward centering/motor mount. I marked a line on a square dowel the same length and used medium CA to glue a small piece of the same dowel as a block.
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This allows me to place some epoxy on the tip of the dowel and smear the inside of the body tube in the perfect spot for the forward CR. I then prepped the inside of the booster tube by sanding with 80 grit and wiping out the dust.
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I just blob up the end of the dowel, insert into the body tube until I rest against the block and rotate the body tube to smear it all on the inside. Repeat blobbing and smearing until the entire inside of the body tube is well buttered. I'd say I end up making a buttered area about half an inch wide where I want the final resting place of the CR to be. You can see the area of the dowel I use to spread the epoxy in the pic below.
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Next I inserted the motor mount tube and forward CR into the booster tube partially so I could add the aft centering ring, tailcone, and motor retainer in the correct order to space the forward CR into the proper position. I checked to make sure I had a nice filet of glue around the top of the forward CR and then set it on its butt to cure!
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Since the tailcone acts as a thrust ring, I was able to place everything on its butt without any supports and didn't have to fear that the motor mount would move out of place inside the booster tube while sitting upright.

After everything had cured, I removed the retainer, and tail cone so I could remove the aft CR. I had wrapped clear scotch tape around the aft CR to use as grab tabs in order to remove it once the motor mount cured. This worked perfectly!

Thats all I have for now except the work I did on the OR file. If anyone wants to see it, its in its early stages with not quite the right fin profile and the weights aren't quite right either. Anyway, I'll update part 2 once I get to work on her again.
 
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I took a little time sanding and smoothing the tail cone sides before wiping on the goof off to shine up the surface. I'm unsure whether I'm going to leave the tail cone as is or paint it when I paint the rocket but for now its glossy black.
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I sanded the glossy surface off of all 5 fins then tacked them on using a method that Mike over at MAC suggested. Butter the root edge and place the fin against the motor tube, pull the fin out and re-butter the root edge, place and repeat at least 3 times in total. I tried it and I really liked it for how large of an internal fillet that made on the motor tube. Since I'm going to be foaming the can, I don't plan on doing any more internal fillets.
Fins Tacked.jpg

I started work on the nose cone by gluing the bulkhead to the coupler that fits inside of the Wildman cone. Then, I slightly beveled the top edge of that bulkhead so it would fit with more surface area contact inside of the tapered shape of the cone body. I used the couple/bulkhead to mark the inside of the cone body by spinning the couple around a few times while it was all the way inside the cone. I pulled the coupler out and you could clearly see where they were contacting so I used some 80 grit to scratch up the surface. Then I glued the coupler-bulkhead inside the nose with some rocketpoxy. I didn't get pictures of the process but heres a shot of the finished cone/coupler and a shot of the bulkhead inside the coupler with an anchor ring.
Bulkhead-Coupler.jpgNose-Coupler.jpg

My biggest project so far was the AV Bay. It took me a while to find a battery I was happy with and a switch that would work for me. I ended up with a 2S 450mah LiPo and a magnetic switch by Featherweight Altimeters. I had a small bracket for the battery made at work, and after that it was just a bit of trial and error figuring out my desired positioning for everything. I went with the Stratologger since I played with it a bit and liked how its configured. I drilled holes and mounted the terminal blocks and charge canisters on the bulkheads. As you will see, I put the hole for the input wire in between the terminal block and canister so I can get to the outside terminals much easier when it comes to installing igniter leads.
Av Sled.jpgBulkhead Wiring.jpgWiring Closeup.jpg

That about sums it up for this update. Next, I'll be marking, masking, and applying fillets on the fins as well as foaming the can once the fillets are installed. Thanks for following along!
 

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Welcome to the swarm. Looking forward to seeing your design choices, techniques and pics/videos. Are you planning on using a tracker, if so have you give it a thought as to whcih one?
 
Welcome to the swarm. Looking forward to seeing your design choices, techniques and pics/videos. Are you planning on using a tracker, if so have you give it a thought as to whcih one?

I was not planning on using a tracker. I plan to use as small of a J as I can get away with. Hoping to fly on an AT J350W. We’ll see how the sims go as to if I’ll need to add a tracker. If it’s above 5000, I may start looking at tracking. Any advice will be appreciated.
 
My story with the Black Fly was similar. Mike and I got to talking about turning an Ethos into a Black Fly. Then he tempted me with what would've been the first, and only at the time, 3" version. Then the 4" comes out. I still don't have a Black Fly. When the Ethos returned as 2.0 I went that route since I had been drooling over the Ethos for a good while. Still would've liked to snag that 3" from ya. But now that I am building Ethos 2.0 alongside a PML Callisto I am reminded just how much I hate doing fillets. So I dodged the 5 finned bullet there, but my 5" project is slated to have either 5 or 6 fins. So...

But to your build:
4" airframe with 5 fins...guessing a finished weight of probably around 7 pounds. 3500 feet or so. With dual deploy and little wind you SHOULDN'T need tracking. But when do we ever have "little wind".

If I can get my Eggfinder to the point I trust it you are more than welcome to use it. You did get the 54MMT right? If you want to cut your teeth on 54mm, I have the 852 case. The J250 would probably keep it lower, or the J275 will put it a bit higher but either one will be less grains to worry about and shorter/fatter cases are easier to clean, at least for me. But I know you have the 720 case so may as well use it right? The J350 is a 9% J while the J250 is a 10%, the 350 has a much better kick off the pad though.

I'm following along. You know how to reach me if you need anything.
 
The J350 is a 9% J while the J250 is a 10%, the 350 has a much better kick off the pad though.
Yes, the 350 has a ton of punch right at the beginning so thats why I chose it. Should make quite a racket! Plus with the length putting the weight further up the rocket I think it may be just that much more stable. And Yes, I did get the 54mm mount.
 
I was not planning on using a tracker. I plan to use as small of a J as I can get away with. Hoping to fly on an AT J350W. We’ll see how the sims go as to if I’ll need to add a tracker. If it’s above 5000, I may start looking at tracking. Any advice will be appreciated.

I am not particularly good at tracking during the up or down part, and rarely do I witness my own landings. I also fly in fields that are surrounded by trees or the fields themselves have crops at varying heights that just love to devour rockets. As such trackers are my friend and I rarely need them until I do, which is most flights, even slow and low.

Re. the AT J350 W, good choice, this rocket likes a high thrust off the pad motor. I sim roughly 3800 AGL on that reload. If you're a Loki fan Another good one for a quick punch off the pad, but a relatively low AGL, is the Loki J820 Loki White. With the same model it sims to 5500 AGL.
 
Bump for opinions on altimeter and to let everyone know I posted an update on the first reserved spot.
 
I use Missile Works RRC2+ altimeters in a lot of things and have had good luck. They are very simple, easy to use, and do a great job. If you want recorded flight data, however, you need to use something else. For someone who is relatively new to dual deploy, or just doesn't want to have to fiddle with electronics, it's the way to go. It also makes an awesome backup altimeter down the road, and it's cheap! I think I own the previous model and three of the current one...
 
I use Missile Works RRC2+ altimeters in a lot of things and have had good luck. They are very simple, easy to use, and do a great job. If you want recorded flight data, however, you need to use something else. For someone who is relatively new to dual deploy, or just doesn't want to have to fiddle with electronics, it's the way to go. It also makes an awesome backup altimeter down the road, and it's cheap! I think I own the previous model and three of the current one...

I currently own both and have actually used neither. I have installed the RRC2+ in a different rocket thats awaiting a maiden flight. So the stratologger is the one thats free right now. That doesnt mean I couldn't just move the RRC2+ back and forth though. As far as logging goes, a JL ALT3 is going along for the ride anyway so I dont care about the stratologgers ability to log my flight. I'm almost tempted to use the RRC2+ just for the simplicity and since I've had more experience with it from building that other DD rocket. I was really just wondering if someone had an opinion on reliability one vs the other. Or if there is some other non obvious reason not to use one or the other. Thanks!
 
I voted the RRC2+ because that is what I have. Lol. And don't you have one too?

The Stratologger, I looked hard at and just never pulled the trigger on it. It does have more features than the RRC2+ and is smaller though. Buy one and fly both. A little redundancy wouldn't hurt.

Edit:
You posted while I was posting. If the RRC2+ is tied up, use the Stratologger. Not sure how easy it is to program. Program it the night before using a checklist to save time and not worry about hot swapping.
 
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While I own an RRC2, it is in a rocket that I am just finishing so I have yet to use it; fired it up but that is about it. I have used the SLCF though and it is a simple to use and reliable altimeter. My take is that they are both good options for a first timer so use what you are the most comfortable using.
 
I'd like to vote both. Pick one and use it. Let the other one go for the ride just logging. Eventually you'll want to run both, for redundancy. If you have aspirations for L3, dual altimeters is a requirement. Get you L2 with one active, then fly with both active to practice. Go with the RRC2+ just because it's so darn simple to set up initially. The add the Strat. You can do more with the Strat if you want (data logging), although I don't bother with that stuff (I just want a successful flight and know the altitude).
 
I was not planning on using a tracker. I plan to use as small of a J as I can get away with. Hoping to fly on an AT J350W. We’ll see how the sims go as to if I’ll need to add a tracker. If it’s above 5000, I may start looking at tracking. Any advice will be appreciated.

Personal experience: My L2 was an 8 foot long 3 inch diameter rocket, and just as it was starting to tip at 4200 feet it found the only cloud in the sky and everyone lost it. I never would have found it except that another flier had a previous flight tip in the same direction a few hours earlier. I ordered my big red bee the following day - and it's saved my bacon several times. I had others give me the same advice I'm now giving you - don't wait until you say 'crap, I wish I'd put a tracker in that' before you buy a tracker.
 
I'd like to vote both. Pick one and use it. Let the other one go for the ride just logging. Eventually you'll want to run both, for redundancy. If you have aspirations for L3, dual altimeters is a requirement. Get you L2 with one active, then fly with both active to practice.

This is good advice and it adds no more risk or complexity to your L2. However as Adrian points out it does give you some experience and confidence towards dual redundancy.

Personal experience: My L2 was an 8 foot long 3 inch diameter rocket, and just as it was starting to tip at 4200 feet it found the only cloud in the sky and everyone lost it. I never would have found it except that another flier had a previous flight tip in the same direction a few hours earlier. I ordered my big red bee the following day - and it's saved my bacon several times. I had others give me the same advice I'm now giving you - don't wait until you say 'crap, I wish I'd put a tracker in that' before you buy a tracker.

This is also sound advice. It reminds me of a common phrases I say to my clients who say things like "that has never happened", my reply "its never an issue until it is". Again like the advice above I see no addition of complexity to the L2, this is secondary and just along for the ride.

One could argue that even though adding these "along for the ride" options does not add to the complexity, it does add to the complexity of prep. I suppose that is a consideration but I would not let it scare me off using them. Simply make a pre-flight prep check-list, think it through do a dry run then just check it off and have someone shadow you. Heck just ask for a pre-flight check list on the forum and you should get some good points for putting one together. Do a bullet point thread and have contributors add bullets to it along with sorting out the order.
 
I'll just add, please beg, borrow, (but don't steal :wink: ) a radio tracker beacon from someone in the club. I'm sure someone will have a spare there. And it'll give you an opportunity to make a new friend :cool: . Seriously, just for added insurance borrow a tracker and be prepared to reimburse them should it get lost or damaged.
FWIW, my L2 was an LOC IROC on a J350 to ~3500' at Bong in WI. No tracker. I look back and think, "That was crazy!" I never fly at Bong w/o a tracker now, even on F motors in my Wildchild...
 
I'll just add, please beg, borrow, (but don't steal :wink: ) a radio tracker beacon from someone in the club. I'm sure someone will have a spare there. And it'll give you an opportunity to make a new friend :cool: . Seriously, just for added insurance borrow a tracker and be prepared to reimburse them should it get lost or damaged.
FWIW, my L2 was an LOC IROC on a J350 to ~3500' at Bong in WI. No tracker. I look back and think, "That was crazy!" I never fly at Bong w/o a tracker now, even on F motors in my Wildchild...
I'll probably have extra trackers... Not sure I'll be flying anything, but I'll be there!
 
I'll probably have extra trackers... Not sure I'll be flying anything, but I'll be there!

I'm good friends with Justin Case. I'd suggest the OP befriend him too. If you have a fellow club member offering... plan for it in your design and fly it!
 
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