(modified) RW Mongoose 29 - 29mm MD "Altitude Seeker": 16,000' & mach 2

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Unfortunately, not for a while. Earliest would be Red Glare in April. It's mostly finished until it warms up enough for me to get a nice paint job on it. I'll be taking 2 weeks off from working on rockets to get finals over with, and then I have another week long break where I think I'll try to build the 3-fin flying case version of this rocket I mentioned at the very beginning of the thread.

So does that mean you will be going to red glare? Or is that still up in the air? Hope to see you there.
 
After a bit of a hiatus, I'm back at it!


I've settled on the design for the flying case version of this rocket, with three, larger fins and no nose weight. I'm hoping it'll weigh in at under 4 oz! Top speed M2.3, and ~13,500':



Being 3-finned, I decided to go with the stock fin material, as its extra thickness helps with the larger span of these new fins. I printed out the fin from OR onto some full sheet sticker paper, and then cut them out (carefully) on the band saw, and finally stack sanded them even. Lots leftover, maybe a third rocket is in order :lol:



I then sanded some bevels into the fins. These were much easier to do, as they were larger and thicker than the previous set. Additionally, with the pointed triangle it was very easy to sand to much towards the tip and actually lower the span of the rocket appreciably; with the clipped delta this isn't a problem. I used the technique were you clamp a thin (1/16") plate down on top of some sandpaper onto a table, and rest the fin on the plate with the fins edge sitting on the sandpaper about 1/2'' from the edge of the plate, creating a nice consistent and shallow angle. I have to say, these turned out really well:





Back to the regular 29mm MD, I began the finishing process with a thin coat of epoxy to start filling in the scratches and texture; finishing CF nicely isn't my strong suit (probably just don't have the patience :lol:), so we'll see how it goes.

What motor are you going to be using for the record attempt?

Probably the CTI I243 White (384.7 Ns, 1.57s burn time, 183.5s ISP). While the I224 Classic may be ever so slightly better (381.5 Ns, 1.7s burn time, 213.12s ISP) due to its longer burn and better ISP, I think the difference is next to negligible as it has a slightly lower impulse, and so the I243 wins for its much bigger, brighter flame and higher amount of smoke :wink:
 
After a bit of a hiatus, I'm back at it!

I've settled on the design for the flying case version of this rocket, with three, larger fins and no nose weight. I'm hoping it'll weigh in at under 4 oz! Top speed M2.3, and ~13,500':



Being 3-finned, I decided to go with the stock fin material, as its extra thickness helps with the larger span of these new fins. I printed out the fin from OR onto some full sheet sticker paper, and then cut them out (carefully) on the band saw, and finally stack sanded them even. Lots leftover, maybe a third rocket is in order :lol:



I then sanded some bevels into the fins. These were much easier to do, as they were larger and thicker than the previous set. Additionally, with the pointed triangle it was very easy to sand to much towards the tip and actually lower the span of the rocket appreciably; with the clipped delta this isn't a problem. I used the technique were you clamp a thin (1/16") plate down on top of some sandpaper onto a table, and rest the fin on the plate with the fins edge sitting on the sandpaper about 1/2'' from the edge of the plate, creating a nice consistent and shallow angle. I have to say, these turned out really well:





Back to the regular 29mm MD, I began the finishing process with a thin coat of epoxy to start filling in the scratches and texture; finishing CF nicely isn't my strong suit (probably just don't have the patience :lol:), so we'll see how it goes.


That looks really cool! :D



Probably the CTI I243 White (384.7 Ns, 1.57s burn time, 183.5s ISP). While the I224 Classic may be ever so slightly better (381.5 Ns, 1.7s burn time, 213.12s ISP) due to its longer burn and better ISP, I think the difference is next to negligible as it has a slightly lower impulse, and so the I243 wins for its much bigger, brighter flame and higher amount of smoke :wink:


The CTI website lists the total impulse of the I224 as only .2 of a newton apart from the I243. OR lists the I224 as having 4 newtons less than the I243, but it still gains 70 ft in the sims.
 
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I think those fins are magnificent.

Well done.

Bob

Thank you! One of the many great techniques I've learned from others here on TRF :)

That looks really cool! :D

The CTI website lists the total impulse of the I224 as only .2 of a newton apart from the I243. OR lists the I224 as having 4 newtons less than the I243, but it still gains 70 ft in the sims.

Thanks, yeah your right. I knew OR was off compared to CTI's published #'s, just got it mixed up a bit. OR seems to be overestimating the I243, and underestimating the I224, and yeah still simulates the I224 as performing better, so the actual performance gap must be around over 100 ft. Thats relatively significant, so maybe I'll go with the I224 then...


Anyways, got some more work done on the flying-case build today. I decided that the fit of the 29mm FWCF tubes just wasn't god enough for this application - a bit of a pet peeve of mine, but I just can't understand why across the board the FW tubes have their ID's sized larger than the actual motor casings, giving a pretty sloppy fit. The couplers fit perfectly (i.e. plenty good tolerance), so why is the ID purposely made larger than the motor OD?

For laying up my own tubes, I've found that a single layer of parchment paper (only slightly overlapping itself by a 1/4 circumference or so) covering the motor cases gives a near perfect fit, no sanding or fitting required. For this tube, I wanted to go light, so I decided on an interior 1.5" Biaxial CF sleeve (0.013"), a 0.006'' longitudinal UNI layer in the middle, and a second 1.5'' Biaxial sleeve for the exterior, which should net me around 0.035". Amazingly, the entire rocket will only be using 5" worth of body tube!

With the sleeves, I've found its best to lay them on and pull them tight with zip-ties before mixing any epoxy - this limits you to 3-4 layers (as far as epoxy will effectively squeeze through the layers) but allows you to get everything pulled down and tight nicely, so that combined with the treated shrink tubing you end up with a very uniform and straight tube. One little trick is that I usually put a bit of oil/lubricant on the motor casing - it makes removal of the tube after its cured easier, and also kind of holds the parchment paper on nicely.



Earlier I threw together a crude little heater oven powered by a lightbulb to warm to ~90 F to speed the cure up a bit, at regular room temperature the aeropoxy laminating resin is reallllyy slow to cure. We'll see how it came out tomorrow!



I also sanded the regular design 29mm MD some more, it's not done and I'm still waiting on some finer grit sandpaper, so no pictures :p Tomorrow I hope to begin assembling the fincan for the flying case, and working on the NC ;)
 
I'm so impressed Coleman. ...
You do some absolutely beautiful work. ....
Good for you man. ....
I can't wait to see the finished product. ....

Teddy
 
Thanks, yeah your right. I knew OR was off compared to CTI's published #'s, just got it mixed up a bit. OR seems to be overestimating the I243, and underestimating the I224, and yeah still simulates the I224 as performing better, so the actual performance gap must be around over 100 ft. Thats relatively significant, so maybe I'll go with the I224 then...

Maybe launch it on the I224 just for the record flight and then fly it a second time with the I243? That way you can get the best of both flights.

I also sanded the regular design 29mm MD some more, it's not done and I'm still waiting on some finer grit sandpaper, so no pictures :p Tomorrow I hope to begin assembling the fincan for the flying case, and working on the NC ;)

After putting the Epoxy on, why don't you clear coat it? Blackjack2564 did it with his Blackhawk 29 and the finish is amazing.

https://www.rocketryforum.com/showt...-Carbon-29mm-Min-Diam-build&p=25972#post25972

https://www.rocketryforum.com/showt...arbon-29mm-Min-Diam-build&p=120935#post120935
 
I'm so impressed Coleman. ...
You do some absolutely beautiful work. ....
Good for you man. ....
I can't wait to see the finished product. ....

Teddy

Thanks teddy, it takes a real effort for me to take my time and do things cleanly, but its worth it in the end. I still marvel at your electronics bays, mine will never look that pretty or clean :eek:

Maybe launch it on the I224 just for the record flight and then fly it a second time with the I243? That way you can get the best of both flights.



After putting the Epoxy on, why don't you clear coat it? Blackjack2564 did it with his Blackhawk 29 and the finish is amazing.

https://www.rocketryforum.com/showt...-Carbon-29mm-Min-Diam-build&p=25972#post25972

https://www.rocketryforum.com/showt...arbon-29mm-Min-Diam-build&p=120935#post120935

I'm not going the clear coat route for a few reasons, but primarily because its winter and I have no where to paint :wink: I've never really gotten consistent results with clear coats anyway (my last MD looked beautiful clear coated, but after sitting in the sun in 80 degree weather the clear coat became totally sticky and ruined after a single flight), and it adds unnecessary weight/thickness. If you look through Jim Jarvis's guides, you can see its possible to get a just as spectacular, but more durable, finish by simply sanding and polishing the CF, and this is what I'd like emulate/learn.


Took the tube off of the mandrel. trimmed off the ends, and then cut it into two pieces: a 2.5" piece for my fin can, and a 2.675" piece for my upper AF. The tube came out pretty nice, with a relatively uniform thickness around 0.035", and weighing 3.3 grams per in, vs. the stock tubing at 0.055" thick and 4.45 g/in. Most importantly, a perfect fit onto the CTI motor casing.


(cut that end a little too close to the ziptie, so a small raised spot where the shrink tubing was held up by the zip tie end)




I found a neat way to sand bevels on the edges of the tubes, by friction mounting the tube onto a hole saw, and carefully spinning them on the stationary bevel jig I used for the fins while applying downward pressure onto the sandpaper with my other hand. It worked well, and was a lot faster/more consistent than doing it by hand.




Parts mock-up:




Finally, sanded the CF coupler to fit and drilled some holes in the section that is glued in to shave a few grams:

 
lookin good Coleman!

Thanks!

Looks good so far. Can't wait to see that thing. You better be at red glare

Thats the plan ;)

So I went up the spectrum of sandpaper starting at 320 and going all the way to 2000, then attempted to polish it with finesse it II and a polishing pad on my cordless drill. Overall I'm really happy with the results, its ultra smooth and has a pretty good wet look, especially in stronger sunlight. These pics really don't do it justice, the filament wound CF is really pretty in the sunlight. Its still far from perfect, or as glossy as possible, but its much a much better finish than I've ever gotten before, and it really is so much more durable and smooth compared to a clear coat which is what I really like about the technique. I also tidied up a few loose ends like the parachute protector and shear pin, so besides ground testing its officially completed! :smile:


Total weight came out to be 198 grams, or 6.98 oz. Not crazy light, but right near optimal mass which is what I wanted. Its so heavy partially because of the heavy NC weighing in at over 65 grams :shock: More relevant to achieving maximum altitude is that the volume is as basically as low as ever possible, so its dense but aerodynamic.



Updated my simulation for the last time, including my measured CG which is slightly back from where I had hoped, meaning my stability margin drops to ~1.6 cal minimum off of the pad and at top speed. Still should be plenty of margin (I hope!). This design has by far the lowest margins in terms of fin size and thickness/stiffness, so I really hope it stays together :eek: With the CTI I224 classic, it sims to a max of 75 g's, mach 2.03 (1532 mph), and 16,251 feet. Hmmmm, a nice goal/hope would be to get 1500 mph and 15,000 ft ;)

View attachment 29mm_MD.ork



 
Geeezzzzzzz is that thing coming out gorgeous Coleman. ....
I'm really jealous, ,, I haven't touched mine yet.....
I'll get to it soon,,, I hope,, lol...

Teddy
 
Thanks!



Thats the plan ;)

So I went up the spectrum of sandpaper starting at 320 and going all the way to 2000, then attempted to polish it with finesse it II and a polishing pad on my cordless drill. Overall I'm really happy with the results, its ultra smooth and has a pretty good wet look, especially in stronger sunlight. These pics really don't do it justice, the filament wound CF is really pretty in the sunlight. Its still far from perfect, or as glossy as possible, but its much a much better finish than I've ever gotten before, and it really is so much more durable and smooth compared to a clear coat which is what I really like about the technique. I also tidied up a few loose ends like the parachute protector and shear pin, so besides ground testing its officially completed! :smile:


Total weight came out to be 198 grams, or 6.98 oz. Not crazy light, but right near optimal mass which is what I wanted. Its so heavy partially because of the heavy NC weighing in at over 65 grams :shock: More relevant to achieving maximum altitude is that the volume is as basically as low as ever possible, so its dense but aerodynamic.



Updated my simulation for the last time, including my measured CG which is slightly back from where I had hoped, meaning my stability margin drops to ~1.6 cal minimum off of the pad and at top speed. Still should be plenty of margin (I hope!). This design has by far the lowest margins in terms of fin size and thickness/stiffness, so I really hope it stays together :eek: With the CTI I224 classic, it sims to a max of 75 g's, mach 2.03 (1532 mph), and 16,251 feet. Hmmmm, a nice goal/hope would be to get 1500 mph and 15,000 ft ;)

View attachment 281041




That looks sick. I'm so envious....... :D
 
Great project.

For future consideration. instead of using plumbing solder, melt down a couple lead fishing sinkers in your mold. DO THIS OUTSIDE on a gas grill with the wind at your back so you don't breathe the fumes. Use a metal soup can and fashion a handle with a set of vice grips to melt the lead.

Also, I generally add nose weight last because that way I don't add too much or too little, especially if I am zeroing in on a specific target weight. I weigh the parts as the build progresses, then weigh the completed section again to factor in weight of glue, sleds, nuts, bolts, etc...even the paint adds weight. Then weigh the final assembled and painted rocket. At that point I know exactly how much additional weight I need to bring it to optimal mass/balance.
 
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So I went up the spectrum of sandpaper starting at 320 and going all the way to 2000, then attempted to polish it with finesse it II and a polishing pad on my cordless drill...

Total weight came out to be 198 grams, or 6.98 oz. Not crazy ..

Updated my simulation for the last time, including my measured CG which is slightly back from where I had hoped, meaning my stability margin drops to ~1.6 cal minimum off of the pad and at top speed. Still should be plenty of margin (I hope!). This design has by far the lowest margins in terms of fin size and thickness/stiffness, so I really hope it stays together :eek: With the CTI I224 classic, it sims to a max of 75 g's, mach 2.03 (1532 mph), and 16,251 feet. Hmmmm, a nice goal/hope would be to get 1500 mph and 15,000 ft...

[deleted amazing pictures]
Wait a second-- Where are my socks? They've been knocked off my feet, and I can't find them anywhere.
 
Thanks everyone! :eek: The 3M finesse it II stuff really does work amazingly, even without a real polishing/buffing tool. The difference between it after 2,000 grit and polishing was huge.

Countersink that screw head!

You can also use one of these: https://www.mcmaster.com/#94355A080. Fill the hex socket in with something like spot putty, then carve it out of there after flight.

The screw head in the pictures is just the single 2-56 shear pin. For the actual flight, I'll just thread it in partway and slice off the top to make it flush :D

Great project.

For future consideration. instead of using plumbing solder, melt down a couple lead fishing sinkers in your mold. DO THIS OUTSIDE on a gas grill with the wind at your back so you don't breathe the fumes. Use a metal soup can and fashion a handle with a set of vice grips to melt the lead.

Also, I generally add nose weight last because that way I don't add too much or too little, especially if I am zeroing in on a specific target weight. I weigh the parts as the build progresses, then weigh the completed section again to factor in weight of glue, sleds, nuts, bolts, etc...even the paint adds weight. Then weigh the final assembled and painted rocket. At that point I know exactly how much additional weight I need to bring it to optimal mass/balance.

Thanks! I actually do have a big old casting ladel that I used for this, along with a propane torch setup on some bricks outside. Since casting it I did acquire some lead weights, so for future projects I'll try melting down the straight lead. Thinking back I'm not really sure why I added the noseweight so early on, it definitely makes more sense to do it at the end :facepalm:. I had weighed all the components very accurately so I guess I just assumed it wouldn't be too different in reality. I was only off by 0.2 cals so the effect is not too bad, but in the future I'll definitely do it last.



Has anyone ever tried using a sabot of sorts to put a 4-fin rocket into a 3-fin tower? I'm trying to decide between that and just 3-D printing some fly-away rail-guides for a normal pad.

What would be really cool would be to tube launch it with a sabot, but that would invalidate it from gettign a TRA altitude record :tongue:

EDIT: A third option would be to make another tower sized only for 29mm/4 fin rockets. I could do a couple 3-D printed plates supporting four 1/4"or 3/8" rods 5-6 ft tall? I wonder whats the most inexpensive material I could use to make the four 5-6 ft tower guides? I feel like I've seen someone do this exact setup somewhere on the forum before, but besides the 3-d printed pieces I cant remember what material was used for the towers...
 
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My socks were knocked off when he said ---
Mach 2 -- 15K ft-- and "I" in the same sentence......
I think that's a contradiction in terms........

Coleman,,
I feel like I've seen someone do this exact setup somewhere on the forum before, but besides the 3-d printed pieces I cant remember what material was used for the towers..
How bout aluminum angle iron,,,
not too expensive,, easy to get at a local Home Cheapo or Lowes,, fairly easy to work with..
Here's a link to an online metal supplier,,
Very thorough,, every different shape in all the different alloys as well..

https://www.onlinemetals.com/

I have a 48" roll of pure pb I got when a contractor was done building an X ray room in Lenox Hill Hospital...
I used to mold my own fishing sinkers,, I have a melting pot you're more then welcome to...

Smokin build Coleman...

This is why you're always laughing at me when I start off easy for the first half dozen flights on a new build.....lol...

Teddy
 
This is a seriously awesome build Coleman. I've been following, but haven't participated yet. I love the idea of these high altitude, high performance builds. The fins look incredible, and I can't get over the insanity of the flying case designs! Glad to see College hasn't interfered with rocketry too much ;)

Nate
 
My socks were knocked off when he said ---
Mach 2 -- 15K ft-- and "I" in the same sentence......
I think that's a contradiction in terms........

Coleman,,
I feel like I've seen someone do this exact setup somewhere on the forum before, but besides the 3-d printed pieces I cant remember what material was used for the towers..
How bout aluminum angle iron,,,
not too expensive,, easy to get at a local Home Cheapo or Lowes,, fairly easy to work with..
Here's a link to an online metal supplier,,
Very thorough,, every different shape in all the different alloys as well..

https://www.onlinemetals.com/

I have a 48" roll of pure pb I got when a contractor was done building an X ray room in Lenox Hill Hospital...
I used to mold my own fishing sinkers,, I have a melting pot you're more then welcome to...

Smokin build Coleman...

This is why you're always laughing at me when I start off easy for the first half dozen flights on a new build.....lol...

Teddy

Thanks teddy, looks like some aluminum angle iron or t-bar should be plenty stiff and very inexpensive. Yeah no test flights for this one :tongue:

This is a seriously awesome build Coleman. I've been following, but haven't participated yet. I love the idea of these high altitude, high performance builds. The fins look incredible, and I can't get over the insanity of the flying case designs! Glad to see College hasn't interfered with rocketry too much ;)

Nate

Thanks Nate! MD's are just plain and simple addicting, lol. This thing on a $35 I motor should go faster and higher than my 3" rockets on $$$ 54mm L's. The bigger motors are cool, but in terms of value little MD's can't be beat! Yeah haven't been as active with going to launches and building as in HS, but I have been managing to design stuff while I'm at college and work on it at home during breaks which has been great. I'm even looking into getting some space in the machine shop to store some rocketry stuff :smile:
 
Wait a minute,,,
Did someone say machine shop ???
In a college ???

OK,,
I think I just mussed up my keyboard....

Teddy
 
Well then. Those are some ambitious goals for that rocket. Just have to see how well everything holds together. I'm going to get started on my own flying case pretty soon. Just need to start gathering components.

Good luck with it. I'll be watching the flight, or at least trying to...
 
.....This thing on a $35 I motor should go faster and higher than my 3" rockets on $$$ 54mm L's. The bigger motors are cool, but in terms of value little MD's can't be beat!......

You and I think alike...... :wink:
 
Thanks for such an impressive thread and sharing your impressive build skills and knowledge. My question is about static ports positioning given your altimeter bay is in the nose - I notice the altimeter you're using is a Stratologger CF, which (if I recall correctly) Perfect Flite recommends situating 4 diameters or so back from the NC curve. How have you circumvented any potential problems on that?
 
Thanks for such an impressive thread and sharing your impressive build skills and knowledge. My question is about static ports positioning given your altimeter bay is in the nose - I notice the altimeter you're using is a Stratologger CF, which (if I recall correctly) Perfect Flite recommends situating 4 diameters or so back from the NC curve. How have you circumvented any potential problems on that?

The holes are about 1.125" back from the NC/airframe joint. The NC itself accepts the coupler for about 1.5", so it is essentially straight air frame for 1.5"-1.75" past the joint. Thus, overall they are about 2-3 diameters back - not ideal, but I *think* it should be fine given other MD flights I've done with holes even closer to the curvature of the NC (though not with this altimeter).

Any more updates on the thread RocketHunter?

Not much, but I have CAD'd up my launch tower design. It will use thin aluminum T bars, 3" square aluminum tube, and some 3-D printed ABS parts. Will be 6 feet long, set up solely for 4-finned 24 mm or 29 mm flights. It will support itself by sliding and clamping onto existing 1010 rail launch pads. There will be four of this setup spaced evenly along the 6 ft length.



Hopefully I'll get to printing the parts in the next few days; I've started machining the square aluminum pieces but haven't finished all four yet. I could've just printed the entire thing in one piece, but aluminum is just cool and its an excuse to use the milling machine :smile:
 
The holes are about 1.125" back from the NC/airframe joint. The NC itself accepts the coupler for about 1.5", so it is essentially straight air frame for 1.5"-1.75" past the joint. Thus, overall they are about 2-3 diameters back - not ideal, but I *think* it should be fine given other MD flights I've done with holes even closer to the curvature of the NC (though not with this altimeter).



Not much, but I have CAD'd up my launch tower design. It will use thin aluminum T bars, 3" square aluminum tube, and some 3-D printed ABS parts. Will be 6 feet long, set up solely for 4-finned 24 mm or 29 mm flights. It will support itself by sliding and clamping onto existing 1010 rail launch pads. There will be four of this setup spaced evenly along the 6 ft length.



Hopefully I'll get to printing the parts in the next few days; I've started machining the square aluminum pieces but haven't finished all four yet. I could've just printed the entire thing in one piece, but aluminum is just cool and its an excuse to use the milling machine :smile:

Nice! Glad to see you back at it. :)
 
The holes are about 1.125" back from the NC/airframe joint. The NC itself accepts the coupler for about 1.5", so it is essentially straight air frame for 1.5"-1.75" past the joint. Thus, overall they are about 2-3 diameters back - not ideal, but I *think* it should be fine given other MD flights I've done with holes even closer to the curvature of the NC (though not with this altimeter).

Thanks for the detailed explanation - I don't have enough experience yet to be able to speak with any authority on whether it will be ok or not, but I very much hope it will be fine. Watching with interest - good luck!
 
The holes are about 1.125" back from the NC/airframe joint. The NC itself accepts the coupler for about 1.5", so it is essentially straight air frame for 1.5"-1.75" past the joint. Thus, overall they are about 2-3 diameters back - not ideal, but I *think* it should be fine given other MD flights I've done with holes even closer to the curvature of the NC (though not with this altimeter).




Not much, but I have CAD'd up my launch tower design. It will use thin aluminum T bars, 3" square aluminum tube, and some 3-D printed ABS parts. Will be 6 feet long, set up solely for 4-finned 24 mm or 29 mm flights. It will support itself by sliding and clamping onto existing 1010 rail launch pads. There will be four of this setup spaced evenly along the 6 ft length.



Hopefully I'll get to printing the parts in the next few days; I've started machining the square aluminum pieces but haven't finished all four yet. I could've just printed the entire thing in one piece, but aluminum is just cool and its an excuse to use the milling machine :smile:


Great, glad you're not the only one using AutoCAD!
 
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