Sub Minimum Diameter L-2050 Build Thread

[Michael Wilson]

Hi all, this will be my first post ever on TRF, so please forgive me if my post isn't in correct format, violates any unwritten laws of TRF or anything else
But without further ado...
A while ago I was looking at the Tripoli single stage records and I noticed that the L record was pretty soft. So as any sane person would do, I went to OR and started to make designs to beat it. Then someone on a Discord server I was on mentioned something about the Loki 54/4000 case and I looked into it and found out that there was an L in that massive case. And I had just seen a post on TRF about a SMD 4 inch rocket and I decided to make sim a SMD with a 54/4000 case and got some ridiculous numbers. Then CAD and web browser was opened and I figured out rough costs and made rough renders when I decided "Hey this looks pretty achievable" I went and asked my mentor if he'd be okay with me making a rocket like this one and he said he'd want updates, but he'd be okay with it. (I'm not old enough to get my L2 cert yet, so I'm doing this with TRA Mentoring) I set myself a goal of getting it done I could launch at Airfest 27. Loki gets the extended bulkhead in stock soon, and I'm getting ready to order an aluminum fin can from Max Q Aerospace. I talked to Mike asked if he could make a 4-fin 54mm fin can with 38mm fins and he said he could with a $25 upcharge. The posts for this will be pretty spaced, but I think it will be a pretty cool project and you'd all enjoy.

Some other details:
Expected altitude right now is about 43000 ft AGL
Max vel. is mach 3.12
Max acceleration is 80-ish Gs (Drag Race this!)
Missile Works redundant RRC2+s or Stratologgers (preferably the stratologgers if i can get my hands on them)
Missile Works Rtx
Mobius Mini V2 action cam
A Screenshot from OR:

Will keep you all updated!

 

[BBrown]

If you are indeed planning on flying this at Airfest 27, you might want to contact the launch organizers. I found this "Absolutely no aluminum airframes or fins attached directly to motor cases will be permitted under any circumstances." on their webpage (www.https://kloudbusters.org/rules.aspx).

 

[Michael Wilson]

If you are indeed planning on flying this at Airfest 27, you might want to contact the launch organizers. I found this "Absolutely no aluminum airframes or fins attached directly to motor cases will be permitted under any circumstances." on their webpage (www.https://kloudbusters.org/rules.aspx).

I have reached out, haven't got a response, but the nose cone and the airframe, if you can call it that, is fiberglass. and they do say aluminum is fine for nosecones and fins.

 

[BBrown]

I have reached out, haven't got a response, but the nose cone and the airframe, if you can call it that, is fiberglass. and they do say alu is fine for nosecones and fons

Just out of curiosity, who did you reach out to? I know these guys fairly well.

 

[Michael Wilson]

I sent it to the kloudbusters email.

 

[GalantVR41062]

I will be watching, I have also built some outlandish birds in OR, one like this but not SMD but a normal 54mm carbon tube setup. My sim was around 42,000'.

I am getting my WM BH 38 and MC Tomach 54mm rockets together to fly on a Loki 38/1200 J 1026CT and 54/2800 L 1040R for practice flying high and recovering them, I have everything but the 54/2800 motor and time.

~John

 

[askrob]

Umm. @Michael Wilson, @BBrown is part of Kloudbusters. If I'm not mistaken, he's the prefect.

 

[Michael Wilson]

Umm. @Michael Wilson, @BBrown is part of Kloudbusters. If I'm not mistaken, he's the prefect.

Yes, I DMed him, I think we worked out that black rock is probably a better bet, as they have a deal with the land owner for no aluminum airframes.

 

[Neutronium95]

I can't wait to see where this goes. Have you simmed it on an M1378 yet? My very rough sims indicated that the same rocket could break both the L and M altitude records.

 

[rfjustin]

And let your indoctrination into implicit and humbling education begin..... right meow...

 

[Michael Wilson]

I can't wait to see where this goes. Have you simmed it on an M1378 yet? My very rough sims indicated that the same rocket could break both the L and M altitude records.

I have and it does, my only problem is location and price!

 

[MClark]

Are you using a tracking device of any kind?
edit, never mind, I see it on first post.

for a TRA record above 30,000 you must use gps

 

[Michael Wilson]

Are you using a tracking device of any kind?
edit, never mind, I see it on first post.

for a TRA record above 30,000 you must use gps

Missle works rtx has the gps tracking built in

 

[Neutronium95]

While designing something similar to this, and as the person who suggested the L 2050, there are a few difficult areas that I've had to think about.

You seem to have a good handle on the fin can, I have a lot more confidence in a bolted Al fin can than any of the composite ones I thought up. The nosecone will be tricky. For optimal performance, you'll have to make it from scratch. Otherwise you'll have to either have a slightly fat section around the nose area, or you'll have to cut down a commercially available cone. The other big area of difficulty is going to be making a reliable recovery system. This is flying significantly higher than anything I'm seriously planning, but there are a few good posts on here about making reliable high altitude ejection charges. Finally, I wish you luck on packaging your electronics into as small of a space as you can.

 

[JimJarvis50]

Records are fun, but any fledgling record hunter should start with a dose of reality. First, records are not easy. To have a successful flight that follows the rules is much more difficult than you might think, although getting valid gps data is much easier now. You need perfect weather and some luck. Second, records are expensive. You might have to try multiple times with multiple rockets. You'll need a custom tower. Multiple trips to BlackRock aren't cheap. Third, Tripoli records are evolving into more of a documentation of high flights than actual records. There are records listed that weren't per the rules.

For the flight you're interested in, there are some technical challenges that I suspect you're not aware of yet. I would recommend that you work your way up, so to speak, so that you can learn those things. I also recommend that you figure out how to design rockets that you can fly in Kansas, BlackRock is a long way from Chicago.

Jim

 

[Michael Wilson]

While designing something similar to this, and as the person who suggested the L 2050, there are a few difficult areas that I've had to think about.

You seem to have a good handle on the fin can, I have a lot more confidence in a bolted Al fin can than any of the composite ones I thought up. The nosecone will be tricky. For optimal performance, you'll have to make it from scratch. Otherwise you'll have to either have a slightly fat section around the nose area, or you'll have to cut down a commercially available cone. The other big area of difficulty is going to be making a reliable recovery system. This is flying significantly higher than anything I'm seriously planning, but there are a few good posts on here about making reliable high altitude ejection charges. Finally, I wish you luck on packaging your electronics into as small of a space as you can.

I’m willing to spend time to make a nose cone and learn all of those skills, what are good high altitude ejection charges? Are they just packed a certain way or are there specific ones I should look for? Would the surgical tube method work? Sorry if this is a dumb question.

 

[Michael Wilson]

Records are fun, but any fledgling record hunter should start with a dose of reality. First, records are not easy. To have a successful flight that follows the rules is much more difficult than you might think, although getting valid gps data is much easier now. You need perfect weather and some luck. Second, records are expensive. You might have to try multiple times with multiple rockets. You'll need a custom tower. Multiple trips to BlackRock aren't cheap. Third, Tripoli records are evolving into more of a documentation of high flights than actual records. There are records listed that weren't per the rules.

For the flight you're interested in, there are some technical challenges that I suspect you're not aware of yet. I would recommend that you work your way up, so to speak, so that you can learn those things. I also recommend that you figure out how to design rockets that you can fly in Kansas, BlackRock is a long way from Chicago.

Jim

I’ve been told that, and I do have rockets that I’m going to fly at mwp, most are smaller, but I have a Blackhawk 38 that I’m sending up not to a degree of altitude that’s comparable, but will give me a better understanding of the technical side of things. Also I’m very humbled that you responded to my post, all the projects you have done are so cool.

 

[conman13]

I'd recommend that you download RasAero to get more accurate altitude/velocity/stability predictions for the high velocity flight where open rocket isn't as accurate. I use a combination of the two, open rocket for basic design and simulation and will then simulate it in RasAero to verify my stability margin. Having a more accurate stability margin will then allow you to further optimize your performance, which in the case of a record attempt will be important. You also mentioned you were using CAD, depending on what software you're using you likely have simulation features that will benefit you. Theres certainly a lot of thought that goes into a build such as this in order to have a successful outcome. I spent a majority of my senior year of college designing a similar 75mm build and doing all of the technical analysis on it to ensure it was all set for when I began construction. It'll be a fun journey with lots to learn along the way so hang in there and enjoy it!

 

[Michael Wilson]

I'd recommend that you download RasAero to get more accurate altitude/velocity/stability predictions for the high velocity flight where open rocket isn't as accurate. I use a combination of the two, open rocket for basic design and simulation and will then simulate it in RasAero to verify my stability margin. Having a more accurate stability margin will then allow you to further optimize your performance, which in the case of a record attempt will be important. You also mentioned you were using CAD, depending on what software you're using you likely have simulation features that will benefit you. Theres certainly a lot of thought that goes into a build such as this in order to have a successful outcome. I spent a majority of my senior year of college designing a similar 75mm build and doing all of the technical analysis on it to ensure it was all set for when I began construction. It'll be a fun journey with lots to learn along the way so hang in there and enjoy it!

Ras aero is great. And what a nice looking bird! I’m really looking forward to all the thing I’m going to learn along the way.

 

[watheyak]

I started a very similar rocket when Scott first released that case. I built a fancy fincan and dead-ended because I got scared. Mach 3.7 is no joke. That was 6+ years ago. Give or take.

Just recently I resurrected that build. I've got a couple threads here indirectly related to the new fincan and nosecone.

I'd start by looking into high temperature epoxy and other materials. Cotronics is a good place to start.

 

[Rocketcamper123]

i am only here for this show and entertainment, carry on.

 

[ether]

for nose cone heat - one approach

https://www.rocketryforum.com/threads/copper-powder-mix-as-ablative.158963/page-2
might want to make it easier by not doing sub-min. you can run a motor frame fin can then above it a regular body tube. makes it a bit easier to handle the nose cone and coupler with standard parts

That is the way i'm going to be doing 98MM motors in the rocket I've built for my L3 cert, I'll replace the 75MM fin can and transform it to 98MM min dia rocket with a Max Q fin can that is mounted on the motor casing. the diff between sub-min and this method in CD terms "should" not be that great

the recovery area looks small on length, are you doing drouge and a main? what size?

why 4 fins, try 3 fins less drag, 4 does help with corkscrew but its a hit on CD, Mike can do custom shapes also. With the fin-can suggest using epoxy as aero fillets to cover the hardware, would make the fin can permanently mounted, but if you are going for altitude something to consider

if you want to stick to sub-min might consider this as your upper airframe

https://www.rocketmotorparts.com/54...glass_Casing_Thin_Wall/p1577809_20536253.aspx
would handle the high G loads

don't see how you are handling attaching the upper airframe to the motor casing, not sure i follow. That area that will see significant forces and has to be very strong to handle lateral loads

 

[BF Rockets]

More human than human, the White Zombie song, is what I think of when I hear the term sub minimum diameter. Sorry if I mistook this for the word association thread. Carry on.

 

[Michael Wilson]

for nose cone heat - one approach

https://www.rocketryforum.com/threads/copper-powder-mix-as-ablative.158963/page-2
might want to make it easier by not doing sub-min. you can run a motor frame fin can then above it a regular body tube. makes it a bit easier to handle the nose cone and coupler with standard parts

That is the way i'm going to be doing 98MM motors in the rocket I've built for my L3 cert, I'll replace the 75MM fin can and transform it to 98MM min dia rocket with a Max Q fin can that is mounted on the motor casing. the diff between sub-min and this method in CD terms "should" not be that great

the recovery area looks small on length, are you doing drouge and a main? what size?

why 4 fins, try 3 fins less drag, 4 does help with corkscrew but its a hit on CD, Mike can do custom shapes also. With the fin-can suggest using epoxy as aero fillets to cover the hardware, would make the fin can permanently mounted, but if you are going for altitude something to consider

if you want to stick to sub-min might consider this as your upper airframe

https://www.rocketmotorparts.com/54...glass_Casing_Thin_Wall/p1577809_20536253.aspx
would handle the high G loads

don't see how you are handling attaching the upper airframe to the motor casing, not sure i follow. That area that will see significant forces and has to be very strong to handle lateral loads

I was actually looking at that thread a few days ago, I’m thinking about doing ablative. As for the upper airframe, I’m machining a piece to screw into the forward bulkhead, and I was going to use that exact part as the airframe and then the phenolic liner as a coupler.

Then for whoever asked about recovery I’m still looking at my options, I may do traditional dual deploy or what I probably will end up doing is using cable cutters to reef the main. The second option seems to be the better one but I’m still open to ideas.

 

[Rob702Martinez]

I'd recommend that you download RasAero to get more accurate altitude/velocity/stability predictions for the high velocity flight where open rocket isn't as accurate. I use a combination of the two, open rocket for basic design and simulation and will then simulate it in RasAero to verify my stability margin. Having a more accurate stability margin will then allow you to further optimize your performance, which in the case of a record attempt will be important. You also mentioned you were using CAD, depending on what software you're using you likely have simulation features that will benefit you. Theres certainly a lot of thought that goes into a build such as this in order to have a successful outcome. I spent a majority of my senior year of college designing a similar 75mm build and doing all of the technical analysis on it to ensure it was all set for when I began construction. It'll be a fun journey with lots to learn along the way so hang in there and enjoy it!

Do you have any more info on the fin can section, please?

 

[conman13]

Do you have any more info on the fin can section, please?

My simulations are predicting a max Q of around M3.9 and therefore I needed a way to create a lightweight composite fin can that would handle such forces. The largest issue with having a composite fin can under these conditions is delamination, in order to combat this I took the concept from someones else's high performance MD build (I believe it was prophecy on here) where he made the leading and trailing edges out of another material to protect his carbon fiber reinforcement. For my proof of concept/prototype I used G10 FR4, the "fin" you see in the photo is actually what I call the fin core. It is a 1/4" thick piece of G10 that has the profile CNC'd into it, the fin face is cut down to leave just under a 1/16" thick center core thickness which will allow for the carbon fiber reinforcement to be laminated into it and the edges protected from delimitation leading edge. I'm using Textreme spread tow fabric which allows for 15 layers of fabric to be laminated into each side of the core. The reinforcement will be done in 2 steps, the first step will be 8 layers of carbon fiber on either side of the core to build up the thickness prior to epoxying them onto the fin can tube. Once the fins have been tacked on the fin can tube, a small fillet will be made to allow a gradual radius for the T2T process. The second step will be 7 layers of T2T, which will also be laminated into the fin core providing protection from delamination. Finally the faces and leading/trailing edges of the T2T region on the fin can will be covered with ablative and everything painted with high temp paint. As I mentioned this was a proof of concept to ensure it could be done properly, the next step will be repeating everything however swapping out the G10 FR4 for magnesium. Magnesium will provide a slight weight savings, increase stiffness, and increase heat dissipation along the leading/trailing edges to further protect against delamination. There will be some tricks to promote the bonding between the magnesium and carbon fiber but that's another story. Hopefully the pictures below provide clarity.

*EDIT*

The fin can tube is hand rolled plain weave carbon fiber with a thickness of 1/16". The leading and trailing transitions will be machined out of aluminum and will both have multiple threaded set screws in order to lock the fin can in place. The leading will be held in place by the force of the set screw against the motor case and the trailing will have the set screws sink down into the machined groove in the case to prevent everything from sliding off the back.


- Connor

 

[Rocketcamper123]

Carbon fiber or fiberglass reinforcement (tip to tip) vacuum bagged or not is unnecessary on any minimum diameter rocket 75mm or smaller. Even some 98mm minimum diameter dont need it. It just adds weight and unnecessary costs. Using the correct epoxy, I use hysol E-120hp. With proper preparation to tube and fin you can exceed Mach 2 with absolutely no issues with a fin ripping off. Of course you have to design the rocket correctly. Yes, in the beginning of my rocket career over 10 years ago I would have said always do tip to tip because I actually did those steps. But now in the last 5 years no tip to tip for me. Now if I was using a high thrust 98mm motor in a min diameter the situation would be different.

 

[watheyak]

Carbon fiber or fiberglass reinforcement (tip to tip) vacuum bagged or not is unnecessary on any minimum diameter rocket 75mm or smaller. Even some 98mm minimum diameter dont need it. It just adds weight and unnecessary costs. Using the correct epoxy, I use hysol E-120hp. With proper preparation to tube and fin you can exceed Mach 2 with absolutely no issues with a fin ripping off. Of course you have to design the rocket correctly. Yes, in the beginning of my rocket career over 10 years ago I would have said always do tip to tip because I actually did those steps. But now in the last 5 years no tip to tip for me. Now if I was using a high thrust 98mm motor in a min diameter the situation would be different.

This motor may be a different situation. In my case, I'm treating it like a CTI N-5800.

I've been a proponent of no tip to tip using 3M Scotch Weld DP460. But not for this.

I am certainly interested in arguments to the contrary. Anyone gone Mach 3.6 with no tip to tip?

Or on the flip side, anyone gone Mach 3.6 WITH tip to tip and had it stay intact?

Michael Wilson, this is your thread that we're all stealing, what's your plan? Inquiring minds want to know!!

 

[conman13]

Carbon fiber or fiberglass reinforcement (tip to tip) vacuum bagged or not is unnecessary on any minimum diameter rocket 75mm or smaller. Even some 98mm minimum diameter dont need it. It just adds weight and unnecessary costs. Using the correct epoxy, I use hysol E-120hp. With proper preparation to tube and fin you can exceed Mach 2 with absolutely no issues with a fin ripping off. Of course you have to design the rocket correctly. Yes, in the beginning of my rocket career over 10 years ago I would have said always do tip to tip because I actually did those steps. But now in the last 5 years no tip to tip for me. Now if I was using a high thrust 98mm motor in a min diameter the situation would be different.

I dont want to take this thread off course however I disagree, T2T can be required for any size build. I don't think you can make the decision based off of the motor casing diameter as there are multiple factors that go into accounting for fin flutter, with motor characteristics and fin profile being the 2 major contributing factors. You could be flying a moon-burner and have a MD rocket with low acceleration but designed for high altitude flights in which case T2T is likely not needed however you could also have a very aggressively burning motor which will have drastic effects on the rockets acceleration. In such instance T2T may be required to prevent fin flutter no matter the material choice and adhesive used. I've had a 38mm flying case using the Loki K1127 shred on me using an aerodynamic fin profile with a span of about 1.4" which used loctite E120-HP for the properly sized fillet. This rocket accelerated to over 90G in less than 2sec and finally shredded right at max Q 11k up. While yes T2T is not always needed its important not to just rely what you think, rather do the analysis to ensure that the construction is adequate. I know that some obviously may not go as in depth into analyzing stresses on basic "daily flier" however in this case where it's a high performance MD rocket it should be part of the design process.

 

[Rob702Martinez]

Carbon fiber or fiberglass reinforcement (tip to tip) vacuum bagged or not is unnecessary on any minimum diameter rocket 75mm or smaller. Even some 98mm minimum diameter dont need it. It just adds weight and unnecessary costs. Using the correct epoxy, I use hysol E-120hp. With proper preparation to tube and fin you can exceed Mach 2 with absolutely no issues with a fin ripping off. Of course you have to design the rocket correctly. Yes, in the beginning of my rocket career over 10 years ago I would have said always do tip to tip because I actually did those steps. But now in the last 5 years no tip to tip for me. Now if I was using a high thrust 98mm motor in a min diameter the situation would be different.

It would be interesting to do a comparison build with said construction and Tip to tip and compare results. I don't think there is a right or wrong way using either technique though.