My High Hopes - Need Your Review and Thoughts (24mm MD)

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rugger09

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Hey Folks, I've just designed a 24 mm Minimum Diameter and have almost all the parts to start construction. The open rocket file is below. I'd really appreciate you folks have a look at the open rocket file and giving me your thoughts and feedback. One specific item I have not completely thought through is how to attach the av-bay to the top of the motor casing. I have a few ideas but nothing solid yet. I have a com-spec tracker - what are my odds that I will find this bird once launched on a G?

Looking forward to hearing from you.

Cheers

Shannon

View attachment High Hopes 24 V1.ork

Project Goal: Attainment of the maximum altitude on a “G” sized motor.
Project Constraints:
1. Deployment system must be suitable to reuse airframe
2. Must be able to find and recover the airframe for reuse
3. Altitude must be electronically logged
4. Maintain stability throughout the flight
5. No machining of parts, all readily available through the normal rocketry vendors (although a small boat tail would be great which I’m having a hard time finding)
6. Usable and stable for motors down to an E size motor
 
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dhbarr

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"Polished" is likely not what the finish will be, certainly not after the first landing.

It's possible to just upscale the fillets as they're only calculated for weight, not for airflow ( ditching the mass object which messed with CG calcs a bit ).

90g is a pretty sizeable nose weight, which I'm guessing was added to get more stability? Or just for coasting upwards? Anyway, better speed off the rail with that e31 with a bit less mass up front and likely some fin tips aft.

Probably safe to set the fins to "airfoil" if bevelling; if truly just breaking the edges, then I take it back :D

12oz hitting the ground at 90mph is probably not a great plan. A very small chute would have substantially more drag.

Hardpoints on CTI 24MM 6GXL is a tough nut to crack. Some RSO's don't seem to like anything affixed to the charge well, e.g. an eyebolt or crossbar epoxied in; an aluminum adapter threaded in.

Since the CTI aft closure protrudes anyway ( providing the thrust ring as well ), I'd probably go with friction fit + HVAC tape for motor retention, and glue in a sandwich of two g10 plates with a fiber centering ring. Add an eyebolt, and Presto Hardpointo!

Anyhoo, this list of miscellaneous opinions is worth precisely what you paid for it. I look forward to someone coming along and providing better advice in short order :)

Cheers!
-dh.
 
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rugger09

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Thanks for the comments DH. I can knock the finish down a bit from polished but I do put in some time on finishing.

I added the mass object to account for the weight of the fillets and then actually found the options for adding fillets properly. I'll delete the mass object.

I added 90 grams to keep things stable (around 2 calibers) while using the largest motor in the design. I was amazed at how much it helps coast too. I'm still unsure if I'm able to get that kind of weight in the nose cone at this point. I ordered some powdered tungsten and will experiment once it arrives. One thing for sure - I'm going to stick with one weight, whatever it ends up to be, regardless of engine.

I was planning on friction fitting motor in place with heat resistant duct tape to make sure things go well. I haven't done that before but read in the threads here that is can be done reliably and successfully. I would talk with a knowledgeable RSO (likely RSO for the event I'm planning on attending) and talk about friction fit and how comfortable they are with a rocket this size.

I sincerely appreciate your input. Looking forward to others poking holes in the design.

Cheers

Shannon
 

retortec

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Another thought to consider as you work with nose weight is maximizing the balance with the given mass. Move everything but the kitchen sink (motor) forward. Many small high powered designs will put the heaviest mass as far forward as possible. As you move back along the airframe you add the lighter components. Finally you eject the drive frame to deploy the recovery. Nose weight can be reduced considerably adding more volume in the airframe. I also agree with dhbarr on polished finishes. But I do go through the effort and get a real performance boost on the first flight. Here is a screen shot of "mass forward" design in my high altitude dart project. This is a CA reinforced craft paper prototype. Test flight was a F150 to 6000ft just past Mach. Final version will be in carbon.

IMG_0094.jpgScreen Shot 2016-12-22 at 7.41.46 AM.jpg
 
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rugger09

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Retortec, thanks for the concept. It makes sense and I will consider it as I further the design and start the build. Can I get a copy of your .ork? I'm guessing lowering the nose weight but bringing the weighty components forward will increase the maximum altitude.

Cheers

Shannon
 

TRFfan

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Thanks for the comments DH. I can knock the finish down a bit from polished but I do put in some time on finishing.

I added the mass object to account for the weight of the fillets and then actually found the options for adding fillets properly. I'll delete the mass object.

I added 90 grams to keep things stable (around 2 calibers) while using the largest motor in the design. I was amazed at how much it helps coast too. I'm still unsure if I'm able to get that kind of weight in the nose cone at this point. I ordered some powdered tungsten and will experiment once it arrives. One thing for sure - I'm going to stick with one weight, whatever it ends up to be, regardless of engine.

I was planning on friction fitting motor in place with heat resistant duct tape to make sure things go well. I haven't done that before but read in the threads here that is can be done reliably and successfully. I would talk with a knowledgeable RSO (likely RSO for the event I'm planning on attending) and talk about friction fit and how comfortable they are with a rocket this size.

I sincerely appreciate your input. Looking forward to others poking holes in the design.

Cheers

Shannon
There are several people who could machine you a boatail. I know of a boatail that acts as a motor holder, so that may solve your problem of retention.

I also noticed that you are using a g65 for the configuration. It that the actual motor you are going to be using or are you going to use a different one? The G65 has a offset core, and therefore as you are flying up you may experience some corkscrewing.
 

retortec

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I like TRFfan's idea of a boat tail motor retainer. I solves a couple problems. The surface area increases for taping the motor and the knurling of the stock retainer is removed. On my last launch I thought tape on the knurling would protect the rails of my tower. It did not and I had to resurface everything. I use the same retainer but a little work on my lathe removed the knurling. I build with a lot with thin craft paper tubes so it may not be an issue but something to watch out for. I agree with the G65 off set core as a potential problem but the G load is way less and the overall yield is close to the same. I will be giving it a try with the above design this spring. With stability at 2+ and fin span at 1+cal I hope it can be minimized. What sort of launcher will be used to put High Hopes in the air?
 

stealth6

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Something to note regarding removing the knurling / making a boattail out of the aft closure:

I did this for a record-attempt 24mm minimum diameter rocket. It's hard to see that clearly in these pics, but I think you all get the idea.
Anywho, I was told that this could easily be considered "altering the stock motor", and would therefore disqualify it from official record flights. It was right on the line, and honestly it seemed like it came down to whoever happened to be signing off on the flight....one official might let it pass, another may disqualify it.

If you aren't trying to set any official records, it shouldn't be a problem (unless you get an RSO who is really a stickler at a club launch), but something to keep in mind at least.

fffff.jpg
I have some better shots of the boattail itself, but TRF's uploader is being wonky at the moment, and I can't seem to post them.

ssix
 

KenRico

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Its class 1 .. no waiver needed .. fly yourself and if you want to set a record ..refly at sanctioned launch .

Kenny
 

rugger09

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Hey TRFfan, I followed your build thread when you were writing it. Did you build it yet? Also, who machined your boat tail for you?

I was planning on using the G65 but I have several other full G motors to try as well. I will compare the various motor configurations versus the simulated flight outcomes. It should be interesting. I was not concerned about the offset core. I’m more interested in the longer burn times which translates into slower speeds (hence a lower overall drag force over the flight path). It should be fun launching multiple times with different motor thrust curves. Of course, this is assuming I find it every time.

Stealth 6: any way I can get your open rocket or rocksim file for that model? It looks sharp!
 

TRFfan

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Hey TRFfan, I followed your build thread when you were writing it. Did you build it yet? Also, who machined your boat tail for you?

I was planning on using the G65 but I have several other full G motors to try as well. I will compare the various motor configurations versus the simulated flight outcomes. It should be interesting. I was not concerned about the offset core. I’m more interested in the longer burn times which translates into slower speeds (hence a lower overall drag force over the flight path). It should be fun launching multiple times with different motor thrust curves. Of course, this is assuming I find it every time.

Stealth 6: any way I can get your open rocket or rocksim file for that model? It looks sharp!
I think a good motor to use would be the G150. It has a short burn time with a lot of thrust in between (and is essentially equal to the g65 in total impulse) so if you find the optimum mass (which you can find in OR by playing around with the sim) then you got yourself a pretty fast rocket (maybe 9000+ ft if optimized).

To reduce drag, a tower would be a pretty good idea. A friend of mine gave me a good design that can be built cheaply and easily. I can send you pictures of it if you like.

About my rocket, no, I haven't built it yet. I am waiting to receive my parts from my friend for the rocket.

I haven't ordered the boatail either yet, but you can get it from Carolina composites. Here is some links that may help.

https://www.rocketryforum.com/showthread.php?132911-Record-Breaker-24-TRFfan

https://www.carolinacompositerocketry.com/main.sc
 
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rugger09

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TRFfan, my local rocketry group has a very nice tower and I will be using it. As for the Cesaroni G150 or the G65 to be the best motor for the best altitude, look closer at the total impulse of the motor: it is 143 Newton seconds. It is called G150 because it burns its fuel in 0.97 seconds. The G65 has an installed impulse of 144 Ns which is more than the G150. It burns the propellant over 2.23 seconds. Since the drag force is proportional to the square of the velocity (example: if the speed increases by two, the drag force increases by four), the G65 is a much more optimized motor for maximal height because the impulse will be used over the flight at a lower speed. The lower speed reduces the overall drag force over the course of the flight and should translate into a higher altitude. This is proven out in the sims but (for me) not in real life. that is what i want to do this flying season.

Cheers

Shannon
 

TRFfan

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TRFfan, my local rocketry group has a very nice tower and I will be using it. As for the Cesaroni G150 or the G65 to be the best motor for the best altitude, look closer at the total impulse of the motor: it is 143 Newton seconds. It is called G150 because it burns its fuel in 0.97 seconds. The G65 has an installed impulse of 144 Ns which is more than the G150. It burns the propellant over 2.23 seconds. Since the drag force is proportional to the square of the velocity (example: if the speed increases by two, the drag force increases by four), the G65 is a much more optimized motor for maximal height because the impulse will be used over the flight at a lower speed. The lower speed reduces the overall drag force over the course of the flight and should translate into a higher altitude. This is proven out in the sims but (for me) not in real life. that is what i want to do this flying season.

Cheers

Shannon
The G65 has an offset core which will result mostly in corkscrewing and as a result you will most likely end up with a rocket that falls much short of its predicted altitude, and the rocket may even end up lost.

Out of the 6G 24mm motors, the G150 has the most impulse (apart from the G65) and the best possible performance. The G117 is another good choice, but the G150 has more ISP and weighs less. I think there is a thread out there on the current G altitude holder. The record flight was made with a G150.

https://www.rocketryforum.com/showt...d-(unoffical-as-of-now)&highlight=maxvelocity

Here is another thread (made by the same person who flew the record breaker) and documents one of his flights on a G65.

https://www.rocketryforum.com/showthread.php?43588-My-Craziest-Flight

The G65 is not necessary an unstable motor, it can be flown in larger, heavier, rockets, but it is in the smaller and lighter rockets that you need to watch out for.
 

dhbarr

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The G65 has an offset core which will result mostly in corkscrewing and as a result you will most likely end up with a rocket that falls much short of its predicted altitude, and the rocket may even end up lost.

Out of the 6G 24mm motors, the G150 has the most impulse (apart from the G65) and the best possible performance. The G117 is another good choice, but the G150 has more ISP and weighs less. I think there is a thread out there on the current G altitude holder. The record flight was made with a G150.

https://www.rocketryforum.com/showt...d-(unoffical-as-of-now)&highlight=maxvelocity

Here is another thread (made by the same person who flew the record breaker) and documents one of his flights on a G65.

https://www.rocketryforum.com/showthread.php?43588-My-Craziest-Flight

The G65 is not necessary an unstable motor, it can be flown in larger, heavier, rockets, but it is in the smaller and lighter rockets that you need to watch out for.
...unless one of your constraints is that the motor be Class 1 ( model Rocket ) compatible :)
 

TRFfan

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...unless one of your constraints is that the motor be Class 1 ( model Rocket ) compatible :)
Yea, but the OP is from canada. Any motor (regardless of thrust) can be used there without a permit as long as it is below 160 n/s total impulse (like for example the G150).
 
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ChrisLentz

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g80tscratch.jpgThis bad boy here has a G80T and weighs 320 grams with the motor in. Projected between 6-7000 feet. Even 5 would be cool. Tomorrow is launch day.
 

ksaves2

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Good luck! You'll need it if you are flying without a tracker. Apogee Aspire-like rockets are a crap shoot as far as getting them back is concerned. A long silver metallic streamer can help flash the rockets presence up high but still if one
flies something this small aggressively, they will eventually lose it. I had fun with my two Aspires but always, always always use SU motors. Kurt
 

retortec

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Nice! Fill her up with tracking powder and get everyone and their dog to put eyes on it. Good luck.
 

OverTheTop

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Interesting though about using the tungsten (19.25g/ml) powder for nose weight instead of something more traditional like lead (11.34g/ml). The only drawback with the powder form will be the interstices between the particles (air, if you don't add filler or bonding agent) which will dilute the high density somewhat. I don't have a feel for how much of an effect it would be however for a random powder. Packing densities can be worked out easily for things like spheres (64% is about as good as you will get without exceptional efforts) but even that can be variable and is only usually determined statistically for the volume/material/method combination.

So it might be a nice part of the project to use Tungsten (bragging rights :wink:), but the volume may end up about the same as cast lead.

Looking forward to seeing this one fly :)
 

ChrisLentz

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G80Tt-14 corkscrewed a bit on the way up but went pretty straight.

[video=youtube;HuaKfhDc6JE]https://www.youtube.com/watch?v=HuaKfhDc6JE[/video]
 

retortec

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Did you get it back? Anything on board recording data from the flight.
 

ChrisLentz

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More of an experimental flight knowing I wouldn't get it back. I put my phone number on it just in case some ice fisherman found it near the shacks we flew by.

I have an Altimeter 3 but it will be some time before I put any money into something that goes that high unless I can successfully recover it. I am looking at a locator system whether it be gps or radio, I am still a ways from there as well. I usually fly under 1000 feet and get some great data from those flights.

This was a 29mm too.

Here is a video of a 24 mm minimum diameter.
[video=youtube;Lc7SF0YPhhE]https://www.youtube.com/watch?v=Lc7SF0YPhhE[/video]

E30T was simmed for about 2500 feet. Nose cone separated and both pieces ended up in the river. Didn't care because I learned from the failure. Pretty cool in the video you can see the deployment charge go off. Barely. Most of my MD rockets cost me about 5$ to build so I don't care if I lose them as long as they teach me something.

Eventually the data will come from the high ones but I'm not rich. lol.
 

rugger09

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Hey folks, apologies for being absent for several months. I quit a job, took a new one, sold a house, bought a house and relocated a family across the country. Now back to rocketry.

I discovered something you may find interesting. While trying to choose the most dense nose cone weight for this little fart of a rocket, I thought I would be well ahead of the pack by trying powdered tungsten. Solid tungsten has a SG of 19.25 (almost the same as gold). I tested the SG of powdered tungsten and was sorely disappointed to discover the SG was 6.785 g/cc. That is a reduction of 65%. Adding epoxy as a binder to the powder when installing into the nose cone would not add enough weight to make enough of a difference. For fun, I tested some powdered magnetite (solid SG of 5.2). It came in at 3.2 g/cc.

I have another rocket I'm finishing and it is a 54mm minimum diameter and I chose to make a cast of the required nose cone weight shape. I then melted 50/50 PB/Sn solder in the mold and used that as nose weight. The SG of that technique worked out to be 8.55 g/cc. Much improved over the powder idea. I'm going to seek out some pure Pb solder as I think that will be my solution.

I'll update this thread over the winter as this build takes shape.

Shannon
 
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