Custom inspired Blackfly

[Brian Kirksey]

I have been admiring the MAC blackfly for quite some time, original design by, Michael Pitfield. One day I hope to own one of his kits. I really like the design, shape, geometry, etc. I wanted to build a scaled down version knowing what I know so far, before I start building bigger scale rockets with different techniques. I am trying to follow the natural progression and not get ahead of myself and go too big, to fast.
Over the last few weeks I have been learning how to use Open Rocket better, a special thanks to the members who have helped me learn more about the software and its features. I have been putting together components and making a few over the last few weeks, dry fitting everything together as I go.

 

[Brian Kirksey]

During a lunch break I made a gauge for the BT60 tube. I figured I could use it to mark the tube through the project and use it as a cutting guide to shorten the length. Worked well, precision fit.

 

[Brian Kirksey]

I also made a few 5-fin alignment templates for the project. I will pencil the lines in as well when the time comes using the OR paper print wrap guide for comparison.

 

[mpitfield]

Hi Brian,

Welcome to the swarm. When I first came up with the BlackFly concept it was intended to be a 24mm MMT. However after a bit of collaboration with Mike it evolved into the 54mm BT 29mm MMT original BlackFly kit from MAC. If you want to do a downscale you might want to reach out to Rick AKA EXPjawa. Rick built a beautiful downscale, I think 24mm MMT and in doing so he created some custom printed components.

If you are new to OR you could start by using an .ork file downloaded from MAC, click here. To downscale just open the file and go to "Edit" > "Scale". It will take you a bit of simple math to get it right but I would start with deciding what MMT you want and downscale the BT to a size that you have access to.

One word of advice. It is not uncommon for relatively short rockets not to be inherently stable and require some nose-weight, and the BlackFly is no different.

BTW the MAC 54mm BT 29mm MMT is a not an unreasonable place for you to start. It performs well on a CTI 2 grain G80 Skid to just over 1,000' AGL and if you use a JLCR it can reliably end up pretty close to the pad.

Good luck and try to post some pics or do a build-thread. If you need any help just PM me.

 

[Brian Kirksey]

Thank you for the warm welcome Michael. I appreciate the history and development behind the Blackfly. I have messaged Rick previously when I was working on the Red Nova build. I saw on his thread/ on one of his photos, the downscaled Blackfly you mention, in the frame. It really stood out and made an impression on me.

I have been playing with the file for some time, many revisions later, lots of mistakes and learning the OR software at the same time, I think I have a final. Indeed, nose weight was added. OR was helpful simulating several engines with impressive figures.

The BT has been interesting trying to find one that exists for the size Im playing with. I tried first trying to find existing Estes adapter and transition part, possibly from another kit. A custom 3D printed BT might be the answer too. Pondering this one part that was kind of slowing the process down for me, I went to work and made a Delrin BT on my Hardinge precision lathe. It fit like a charm. I am still developing this BT. Still not sure if the lathe part or the printed one will be superior.

Thanks again for the hospitality, reaching out, and for the offering of help.

Brian Kirksey

 

[Brian Kirksey]

The black Delrin BT I made on the lathe.

 

[Brian Kirksey]

Before I wanted to invest the time in making fixtures to make Balsa wood fins and cut them on the CNC mill I thought I would try the tried and true way, the Xacto. I machined a template for my fin. Even though my knife was sharp it took many passes to cut through the wood.(I should have changed the blade like the video suggested) My guide scale kept sliding round and I noticed when the first fin was complete it looked pretty good, probably good enough. One of the edges was not perfect but had a little angle to it. When I add my edge radius to the fin edges the little angle would not matter. We have access to a laser at work so I just to cut them on a Laser and totally took the labor and knife risk out of the mix.

 

[mpitfield]

Nice work, looks like you have access to some nice tools. Regarding the delrin tailcone, just make sure that the overhang is far enough away from retainer. The exhaust gases tend to get sucked by the base drag and the aft end can get a little crispy. Are you using fin tabs or surface mounting the fins?

 

[Brian Kirksey]

Thanks Michael,
It's pretty handy growing up in a fabrication shop located where we are. The type of work and projects we get asked to make and the machines we use.
I appreciate you mentioning and advising about the tailcone. Before I played with making one, the thought crossed my mind about researching a more exotic plastic that might have better heat resist properties, Ultem & Peek, which we use at work, has higher heat resists, but might be more brittle. This delin/ acetal model was my first crack at it. I'll have to ask some of the engineers for their recommendation.

I played with several OR models and eventually went with Surface mounted fins, even though I really like the fin tabs for a more solid aft end. Most of the Estes rocket kits I have made to date use "D" engines and have not had a fin tab through design. I think and I am kind of guessing but I think once I get up to "E" loads, I would prefer the tab through to MM. I also am looking forward to the future to where I can try to make rockets with stronger materials than paper, G-10, Micarta, carbon Fiber, etc.

 

[Brian Kirksey]

Dry fitting/ confirming the fit.

 

[mpitfield]

Looking great Brian. Are you going to sand that glassine finish off the tube before you glue anything to it?

Have you picked out your paint scheme?

 

[Brian Kirksey]

Yes, I plan on filling the spiral groove with CWF and then sanding the tube. I am pretty cure I will be adding radius edges on the fins (3 edges). I considered chamfers but the Basswood might not be durable enough compared to something like G-10 or Micarta. I will inspect the NC for any oddities in the blow mold, and fill if need be.

I have not chosen a color scheme. I tend to gravitate towards the red and white combos, and thought about something orange, black and white. But I am am not settled, and I continue to return to the original dark schemes in OR.
Black, greys, and olive drabs is another consideration. Just have not hit anything yet that screamed, this is the one.

 

[Brian Kirksey]

Now that the Thanksgiving holiday has past I can get back this build. I went ahead and added a full radius to the fore and aft edges of my fins. I also added a minor radius to the fin edge. I applied a thin coat of CWF to the BT60 main tube & then sanded the surfaces smooth once dried.

 

[Jozef]

Good job on the BT60. Most builders just fill the spirals on body tubes and don't realize that cardboard airframes are full of surface irregularities. An alternative to brushing thinned cwf is to use a single edge razor blade and "squeegee" the cwf thinly on the surface. What ever method you used worked well.

 

[Brian Kirksey]

Good job on the BT60. Most builders just fill the spirals on body tubes and don't realize that cardboard airframes are full of surface irregularities. An alternative to brushing thinned cwf is to use a single edge razor blade and "squeegee" the cwf thinly on the surface. What ever method you used worked well.

Thank you. Previously on my first rocket build, lunchtime Bullpup, Neil pointed out helpful tips regarding thinning the CW before applying it to the tube and fins. This made the work much easier both applying it and removing it.

 

[Brian Kirksey]

Last night I was at the work bench again. This was the part of the kit I was most nervous about. The last week asking questions about motors , types, sizes, etc. My experience has only been with Black powder disposables. I wanted this rocket to be versatile and to be able to use a variety of motors.


Test fitting a thrust ring option.



Adding the Front spacer and thrust ring (not visible).




Setting and gluing the aft spacer.

 

[Brian Kirksey]

Rear spacer: glue added Retainer epoxied in place.



Tape flag added (hopefully) for less pressure in one point on inner rocket wall or experiences bad angle coming down to earth.


Elastic: (2.4x) the tube length.

 

[Brian Kirksey]

With no prior experience using a retainer or building a rocket with one,I was not sure how long the end should stick out of the boattail. I counterbored the Boattail to accept the knurled retainer ring for a cleaner look but felt it was kind of hard to get to it and remove it so eventually the decision was made to have it stick out mostly for access to the knurled ring (function over beauty), and it is still clean in appearance and functions well.

I am wondering if I should glue the boattail in now or leave it in the raw state?
I can always glue it in after painting.





Double checking bore is free from any dirt or risidule glue with AT 24/40.

 

[Brian Kirksey]

Fixture and fins.

 

[Brian Kirksey]

I have applied 2 coats of glue for the fin fillets. I generally keep the radius pretty small.
I am now looking at 4-5 paint schemes. This is harder than it sounds trying to find the right combination of colors.

 

[mpitfield]

Wow Brian you are very detail oriented, which is always nice to see. Also nice execution, looking forward to seeing this one fly.

 

[Brian Kirksey]

Thanks Mike!
I am learning more and more with this build and had told myslef stick to the plan and the path once I started. I had planned on using launch lugs on this rocket. Now I am researching and leanring about buttons. I am not sure if I am beyond the button option yet. If so, I will proceed with lugs. I also want to see what launch platforms are available at the local organized launches before I commit to make sure this blackfly inspired rocket is compatable. Originally 3/16" sized lugs were my go to but they might not be as popular as the 1/4" or rails.

Looking great Brian.
Have you picked out your paint scheme?

I have been tossing all sort of painting ideas around during this build. I am getting closer I think. I found two aircraft paint jobs that are amazing and that are speaking to me.

 

[mpitfield]

I had planned on using launch lugs on this rocket. Now I am researching and learning about buttons. I am not sure if I am beyond the button option yet. If so, I will proceed with lugs. I also want to see what launch platforms are available at the local organized launches before I commit to make sure this blackfly inspired rocket is compatible. Originally 3/16" sized lugs were my go to but they might not be as popular as the 1/4" or rails.

I have used the micro buttons here https://rail-buttons.com/minimicro.html. The 10mm rails are becoming more popular at some HP launches I attend in the US. When I attend local launches in Canada I have to bring my own so I picked up a 900mm 10mm rail off Amazon. I haven't made an adapter for it yet so I usually use a couple of c-clamps to attach it to a 1010 rail.

I have been tossing all sort of painting ideas around during this build. I am getting closer I think. I found two aircraft paint jobs that are amazing and that are speaking to me.

At the very least I am seeing a black nosecone in your future. Both themes are nice. Of course the Dutch Falcon is such a cool looking paint theme, but the Dolphin theme is likely a lot easier to pull off. Either way I like where you are heading.

 

[Brian Kirksey]

Added the weight to the nose cone and simulated more flights with varius engines. so much fun!
Added one more fillet treatment to the fins and did a light sanding. Getting closer to painting time. (Gulp!)

 

[Tobor]

Hey Brian,
Great job on the baby BF. And welcome to the swarm!

Oh btw, have you contacted Mark at Stickershock about a set of downsized BlackFly decals for this bird?

 

[Brian Kirksey]

Hey Brian,
Great job on the baby BF. And welcome to the swarm!
Oh btw, have you contacted Mark at Stickershock about a set of downsized BlackFly decals for this bird?

Tobor,
Thank you for the comments.
Yes, regarding Mark @ Stickershock. Mark and I are working out the details currently with this concept. I would be a fish out of water with this theme, without him.

 

[Brian Kirksey]

Beats me where the primered photo went, oh well. Today I put another coat of Canyon Satin Black on this "Black" Fly. It really looks like a blackfly now I might sand it one more time a little finer for one more coat.
In the meantime I have been doing lots of rocket science reseach and learning more about the hobby and its options. I hope to conclude this rocket project soon. I am looking forward to launching it.