Thanks Dave, but one thing I am good at is getting into the dog house, so this won't help me.
MAC BlackFly build thread
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Thanks Dave, but one thing I am good at is getting into the dog house, so this won't help me.
I’m still bumbling along with mine, to say this has been an incredible learning experience would be an understatement. I have only ever built kits before this by following the instructions to a “T” and using the motors they told me to. Never having to make decisions on my own.
I would like to start this post with what I dubbed “Nose Cone Follies”. Upon recommendations in this thread, I purchased the 54mm x 34mm nose cone bay kit and proceeded to saw off the end of the stock nose cone and everything fit great. So far, so good. Then took a break from it to work on painting, repainting and repainting the body of the rocket (more on that later). I got back to the nosecone and decided I needed to add weight to the nose before gluing the AV bay in as it wouldn’t accessible afterwards. I then ordered the 3-D printed altimeter bay kit which was to have a 6.25” ¼-20 aluminum all thread rod that you could bolt weight(s) to and wouldn’t need to epoxy lead shot in the nose, “this is perfect” I thought!!! This is what I thought I was getting…
This is what I got…
The 3-D printed piece was too wide to fit in the AV bay and it didn’t look to me like there would be any room in there to add anything else. Additionally, the aluminum rod was barely 6” so there was no way to bolt on additional weight. Dangit! After pondering this over a few adult beverages, I decided to grind off the lug and approximately ¼” of the width to get it to fit and do the slot trick on the forward bulkhead like Mike did. Hey, this might work after all!
Then the nose weight issue reared its ugly head again. In a fit of desperation I found two 7-1/2 load shotgun shells discarded in the duck boat. Removed the shot and epoxied it in with dowel method drilled through the tip of the nosecone. Turns out that two ¾ oz dove loads (minus what I spilled all over the place) is almost exactly 100gms with epoxy!
That is probably more than necessary for what I will probably need but it’s done, AV bay glued in now, I can move on with my life!
I would like to start this post with what I dubbed “Nose Cone Follies”. Upon recommendations in this thread, I purchased the 54mm x 34mm nose cone bay kit and proceeded to saw off the end of the stock nose cone and everything fit great. So far, so good. Then took a break from it to work on painting, repainting and repainting the body of the rocket (more on that later). I got back to the nosecone and decided I needed to add weight to the nose before gluing the AV bay in as it wouldn’t accessible afterwards. I then ordered the 3-D printed altimeter bay kit which was to have a 6.25” ¼-20 aluminum all thread rod that you could bolt weight(s) to and wouldn’t need to epoxy lead shot in the nose, “this is perfect” I thought!!! This is what I thought I was getting…
This is what I got…
The 3-D printed piece was too wide to fit in the AV bay and it didn’t look to me like there would be any room in there to add anything else. Additionally, the aluminum rod was barely 6” so there was no way to bolt on additional weight. Dangit! After pondering this over a few adult beverages, I decided to grind off the lug and approximately ¼” of the width to get it to fit and do the slot trick on the forward bulkhead like Mike did. Hey, this might work after all!
Then the nose weight issue reared its ugly head again. In a fit of desperation I found two 7-1/2 load shotgun shells discarded in the duck boat. Removed the shot and epoxied it in with dowel method drilled through the tip of the nosecone. Turns out that two ¾ oz dove loads (minus what I spilled all over the place) is almost exactly 100gms with epoxy!
That is probably more than necessary for what I will probably need but it’s done, AV bay glued in now, I can move on with my life!
Hi Deke,
I think this will be a great experience for you, as well as a bit frustrating from time to time, which just means you are pushing it. So far you look like you have a good grasp on things. What do you plan on putting in the nosecone AV bay?
One thing I have observed while launching mine is that due to the nose heavy design, upon apogee deployment the nosecone pulls the booster down and in one case the main deployed resulting in the booster dropping through it. Fortunately it sorted itself out but I am now experimenting with a very small drogue attached to the nosecone to slow it's decent enough to allow the booster to descend at an equal rate, or ideally a bit faster. This issue is not uncommon for a nose heavy design, to the point where I have witnessed some higher alt drogueless decents where the nosecone and the booster align resulting in a nice clean air-stream for the rocket to come in almost ballistic.
As for the painting, that will dog you for a while as it is frustrating even when you think you have your technique down. That is one area that I am continually experimenting in. As a matter of fact I just ordered some Molotow Liquid Chrome to experiment with on a carbon fiber build where I plan on painting one fin chrome. In this case I ordered the 1mm, 2mm, and 4mm pens along with a 30ml refill, which is what I plan on using in my airbrush for the task. It will either turn out great or be one big mess of an experiment that I then have to sand off and start over...it wouldn't be the first time.
Anyway good luck, keep at it, and don't hesitate to shoot me a PM if I can be of any help.
I think this will be a great experience for you, as well as a bit frustrating from time to time, which just means you are pushing it. So far you look like you have a good grasp on things. What do you plan on putting in the nosecone AV bay?
One thing I have observed while launching mine is that due to the nose heavy design, upon apogee deployment the nosecone pulls the booster down and in one case the main deployed resulting in the booster dropping through it. Fortunately it sorted itself out but I am now experimenting with a very small drogue attached to the nosecone to slow it's decent enough to allow the booster to descend at an equal rate, or ideally a bit faster. This issue is not uncommon for a nose heavy design, to the point where I have witnessed some higher alt drogueless decents where the nosecone and the booster align resulting in a nice clean air-stream for the rocket to come in almost ballistic.
As for the painting, that will dog you for a while as it is frustrating even when you think you have your technique down. That is one area that I am continually experimenting in. As a matter of fact I just ordered some Molotow Liquid Chrome to experiment with on a carbon fiber build where I plan on painting one fin chrome. In this case I ordered the 1mm, 2mm, and 4mm pens along with a 30ml refill, which is what I plan on using in my airbrush for the task. It will either turn out great or be one big mess of an experiment that I then have to sand off and start over...it wouldn't be the first time.
Anyway good luck, keep at it, and don't hesitate to shoot me a PM if I can be of any help.
Thanks Mike! That is very good information you posted above. I will probably be putting an altimeter in the AV bay at some point, I drilled the requisite holes in the AV bay walls and nose cone similar to what you did for that very purpose. Looking forward to seeing how the chrome goes!
gfunk
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Hey Michael,
Here's where I ended up with my abbreviated tail cone, probably a bit less than 1/4" of material removed. I was trying to still cover the end of the aeropack. Should have flight results in November?
I foamed my fin can after double dipping the fin edges on the MMT. Minimal external fillets still to come.
What's the biggest motor anyone has flown a Black Fly on? Given the short rocket length, how close are people cutting the margin of stability?
Is the "heavy nose dragging the booster / deploy chute into booster" problem worse because you're using a JLCR and the system has time to start coming in fast? Wouldn't longer kevlar and main at apogee minimize this? Interested in your tiny drogue results.
CzTeacherMan
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I'll be putting a 29-6 grain in line at MWP... I'll let you know how it goes
Man that thing is going to be a tank with a foamed fincan. The tailcone looks great, it looks like you trimmed just the right amount.
The biggest motor I have flown is the CTI G106 Skid to 2200'. With that motor I am sitting with a margin of 1.3 cal and it has been my favourite motor so far. I have only launched it three times, the other motors are the CTI G80 Skid which was also dead straight and hit 1300 AGL, and the last motor I flew was the AT G79W, which was stable but with a slight wobble as the boost phase progressed, still a respectable performing motor and I would confidently fly it again.
I was actually hoping to attend a L/MPR launch today hosted by CRC (Cambridge Rocketry Club), which is a couple hours outside of Toronto. However family and work commitments prevented it. I was planning on launching the AT G64W and CTI G250 Vmax, which I suspect will be my favourite motor. At this stage I may not launch again until next spring. I look forward to your flight results. The only other BlackFly I have seen launched did loops off the pad because the builder did not sim it or realize it needed nose weight. He may have added some weight and it may fly this next weekend, if so I will ask and get some results.
Bottom line on stability with this rocket or a rocket of this design is it needs nose weight and you should sim everything first. I will fly well on a relatively wide range of motors, but not every motor in it's class, not unlike any other rocket for that matter.
The nose dragging down the booster is a new thing to me so I am still finding my way through it. It is not new to the hobby and not that uncommon, although I would not go so far as to say that it is a common thing either. I have seen it happen on several drogueless flights while attending launches, watched YouTube videos that clearly demonstrate the phenomenon, and have spoken to other rocketeers about it. I have also seen it used as one of the justifying factors that the drogue camp uses when debating the drogue vs. drogueless debate that pops up once in a while.
Because my last flight had the main fall out of the JLCR (due to me not doing the shake test) at apogee, I never got an opportunity to see if the small drogue I put on last min would of resulted in any appreciable affect. So I will have to get back to you on that strategy with this rocket. I do know however the strategy is common and proven, so there is no reason why it wouldn't in this case. I also know from all my HPR rockets, which are all dual deploy, that sizing of the drogue is a bit of an art and often takes a few flights to dial in the right size and config.
As far s the JLCR exacerbating the issue, I would say no, in fact it should decrease it because it increases the CD of the overall deployed package. Longer recovery harness, within reason, at least in my mind would not mitigate this effect. I could be wrong so I would love to hear other opinions. The way I see it is because the nosecone is more aerodynamic with a lower CD, and relatively heavy as compared to the booster and fins, it descends at a faster velocity and pulls the booster down and inline behind it. This appears to result in a deployed rocket but aerodynamically stable, so it comes in almost ballistic.
If your field is appropriate and you can apogee at main with a worst case long walk, then yes this is not a concern so don't worry about it. I don't have the luxury of launching from sites like that so hungry rocket eating trees, thirsty streams and ponds, and even roads are always on my mind when launching. So my strategy is typically anything approaching, or over 1,500' AGL, is to always consider dual deploy.
Holly crap Eric, man go big or go home, now that I can't wait to see. What motor is that, I204
, what is your stability margin? I just had to sim that one up 5800" AGL @ 900'+f/s lol. With the 6 grain case how the heck are you packing all the recovery gear?
gfunk
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Michael,
Thanks for all that info! I think my first flight may be on a Pro29 G80, G126, or H163 next weekend if the USFS lets us launch at Pawnee NG. I'll shoot for at least 1.3 cals of stability.
I finished up the nose cone and external fillets this week and received a 30" Spherachute today from Julie. Now time for a bunch of primering and sanding...
I added ~2oz of nose weight by making a brass tip with an extended base to replace the aluminum tip (brass is almost 3X as dense). This seems like an easy and adjustable way to add nose weight. Can stack up more washers on the 1/4-20 bolt if I need more. Also made an O-ring sealed delrin bulkhead and sled for the new Missile Works T3 GPS tracker, which so far has ground tested great. I recessed the bulkhead in the NC coupler to give a bit more room for recovery gear. This tracker will also eventually get time in my MAC Scorpion 54mm XL which will see some big 38mm Js.
Thanks again!
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Wow very nice build and details, love the kapton tape touch and brass tip. Please post your results, pics videos, etc. I am looking forward to seeing what you do for the theme.
0011001100
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That brass tip looks beautiful. I want one now XD
gfunk
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Black Fly theme is simple for now, though I kinda like the metallic black rusto with the brass tip. Need to email Mark at Sticker Shock. Just got the OK from USFS to launch it next weekend with NCR! Hoping for L2 on the same day. If I could do it again I would ask Mike about a longer body tube to allow for longer motors.
Since we're milking this NASA space suit for all it's worth... also have a MAC Scorpion XL in the works (looking to hit 10k and break Mach on a J570) and probably our last water rocket launch of the year today to almost 500' AGL (not pressurized for this picture, dish soap is just foamy from filling!).
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CzTeacherMan
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Black Fly is prepped with a CTI 29/6, 315-H235-BS, ready for MWP
Do you mean the H255BS? Please post picks of how you packed the recovery gear with that 6 grain motor.
CzTeacherMan
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Yes, H255, sorry.
The shock cord got z-wrapped around the motor tube (motor in first, pack cord around it). Then chute bundle goes into nosecone, tracker into the tip (taped to shock cord), chute bundle in the shoulder of the NC with a couple inches sticking down into BT. I've used just about every spot of space. I'll post pics when it's fully loaded at the field, too tired now. LoL!
So what you're saying is there's a little space left to put an even larger motor in it.
CzTeacherMan
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0011001100
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Why not an H399WT? It might break the sound barrier before leaving the rail but is that a problem
Why not an H399WT? It might break the sound barrier before leaving the rail but is that a problem
See the sims below, it looks like the H255 gets another 500', over the H399. Max velocity is even slightly higher on the 255, but the 399 certainly beats it in Gees and likely in a drag race. I like the look of the I204 Imax.
0011001100
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Hmm interesting. You should sim the other I motors as well. I224Cl is a pretty good one.
Just for fun I simmed up the I243W and I224CL, and they are so close in performance. It makes me wonder why they would produce two motors that are so close, at least in my sim. Heck even a classic vs. white effect is pretty close.
Of course as per the pic cramming a 6XL case in my BlackFly, would be a challenge if not impossible. However it sounds like Eric built his BlackFly with long motor options in mind. I would love to see someone stick either one of these motors in their BlackFly.
0011001100
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Just wrap the parachute and shock cord around the motor XD
For real though i didn't realize the length difference so yea that wont fit.
For real though i didn't realize the length difference so yea that wont fit.
CzTeacherMan
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Did it with a much smaller rocket...Why not an H399WT? It might break the sound barrier before leaving the rail but is that a problem
https://youtu.be/qL2YG9Jzsuc
CzTeacherMan
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I'll pick one up at the launch and fly it again.... All in the name of scienceJust for fun I simmed up the I243W and I224CL, and they are so close in performance. It makes me wonder why they would produce two motors that are so close, at least in my sim. Heck even a classic vs. white effect is pretty close.
Of course as per the pic cramming a 6XL case in my BlackFly, would be a challenge if not impossible. However it sounds like Eric built his BlackFly with long motor options in mind. I would love to see someone stick either one of these motors in their BlackFly.
love the laugh at the end.
Your sacrifices will no doubt be noted right up there with von Braun. Another video with the same crowd would be great.
0011001100
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Much better than my attempt:
First ripped the fins apart making confetti: [video=youtube;6Qh5Xvsq21w]https://www.youtube.com/watch?v=6Qh5Xvsq21w[/video]
Second catoed and completely destroyed the booster and the casing: [video=youtube;tBqgVAaDO90]https://www.youtube.com/watch?v=tBqgVAaDO90[/video]
Btw the second flight the bottom half was wrapped in fiberglass with fiberglass fins. They survived its just that the ejection charge went off right as the motor lit and the casing pressure came out the top and the side of the rocket.
GrouchoDuke
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The I224 is really fun in small rockets. So are the other Pro29-6GXL motors. Ba-bye!
CzTeacherMan
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Black Fly flew successfully on an H255-BS. It was awesome. Pics and video when I get home
We need our rocket porn now!
