Cardboard/Plywood Parts to a 100k

[rfjustin]

As stated several times before, I am not looking to do this challenge. I have no access to black rock and barely any access to a waiver > 4500 ft. I did order a custom LOC Magnum for 98 mm motors though and I plan to post on that build. If I get to MDRA or Potter I can try pushing that rocket.

Oh I get it now, its one of those pointless, "Change my mind" type of things...

 

[AlexBruccoleri]

Oh I get it now, its one of those pointless, "Change my mind" type of things...
View attachment 500919

It is one of those "Here is a hard challenge, how might it be done and what are going to be the tough parts" types of posts. And for what it is worth, hobby rockets in general rarely have a "point". That is what makes this so cool in my opinion. The fact that we all do this for "fun" is bizarre and amazing all in one exciting pile. I think this challenge is fun to think about and thanks to all the people who shared their ideas.

 

[David Schwantz]

Every L1, L2 and L3 rocket has a "point". Along with record breaking rockets, all rockets that may be testing new equipment before it goes into something more complex.

 

[Titan II]

I have no access to black rock....

Everybody has access to Black Rock. Given that you competed at the World Spacemodeling Championship in the Czech Republic, Black Rock should be a piece of cake.

 

[AlexBruccoleri]

Everybody has access to Black Rock. Given that you competed at the World Spacemodeling Championship in the Czech Republic, Black Rock should be a piece of cake.

I was more hardcore as a teenager for sure! But fair point, I have *some* access to Black Rock. Certainly not enough to do iterative flight testing.

 

[OzHybrid]

I was more hardcore as a teenager for sure! But fair point, I have *some* access to Black Rock. Certainly not enough to do iterative flight testing.

Ok. So you're not going to do this yourself. (This makes one of your construction requirements that it can break down into manageable sections to fit into your flat kinda moot) You have no access to a site on an ongoing basis to do testing. Absolutely no-one else is showing any sign of it being a project they'd be taking on.
With the available motors that are certified(another requirement) it doesn't seem possible.

I enjoyed Jim's guidance section. Now back to 3D printing. Have you all seen my new fin can designer with fillets.
https://www.rocketryforum.com/threads/3d-printing-file-repository.150351/page-4#post-2228775 (Hijack back to reality)

in the words of Eminem, Lose Yourself
snip:-
The clock's run out, time's up, over—blaow!
Snap back to reality, ope there goes gravity, ope
There goes Rabbit, he choked, he's so mad but he won't
Give up that easy, no, he won't have it, he knows
His whole back's to these ropes, it don't matter, he's dope

Norm

 

[AlexBruccoleri]

Ok. So you're not going to do this yourself. (This makes one of your construction requirements that it can break down into manageable sections to fit into your flat kinda moot) You have no access to a site on an ongoing basis to do testing. Absolutely no-one else is showing any sign of it being a project they'd be taking on.
With the available motors that are certified(another requirement) it doesn't seem possible.

I enjoyed Jim's guidance section. Now back to 3D printing. Have you all seen my new fin can designer with fillets.
https://www.rocketryforum.com/threads/3d-printing-file-repository.150351/page-4#post-2228775 (Hijack back to reality)

in the words of Eminem, Lose Yourself
snip:-
The clock's run out, time's up, over—blaow!
Snap back to reality, ope there goes gravity, ope
There goes Rabbit, he choked, he's so mad but he won't
Give up that easy, no, he won't have it, he knows
His whole back's to these ropes, it don't matter, he's dope

Norm

I think we have a different opinion on brainstorming ideas. I also suspect some people on this forum may go and try to push the boundaries of paper rockets. Unlikely to a 100k, but likely more than most think is possible a priori.

 

[dhbarr]

If you add a 4th stage you can probably keep your MD cardbirds bouncing from about M 1.2 to about M 2.5. Of course those pesky forces would blast apart the unreinforced interstages....

 

[AlexBruccoleri]

I changed my mind and have new info for this thread.

1. I may start this project with hardware.

2. I discovered something very cool. RCS sells motor grains and all the parts to make motors. While I do not endorse any form of EX work in an apartment, one could easily buy the parts and assemble the hazardous parts on the field. So I am fine with EX motors for this challenge. (Note, using the motor tube as the primary structure or using motor tube components kinda defeats the point, but if you use RCS or Loki parts, it is fine.)

3. Lake Winnipesaukee! I flew there this winter and it is the Black Rock of the East when frozen. They may get a 25k ft waiver too, but that is not certain. Either way, for a narrow window in time, it is a place to test extreme projects.

I still have a LOC Magnum on order for 98 mm motors and they have the Laser Loc 3.1 in stock. Both of those are good "apartment style" builds that I can push the limits on. I do not think I will ever achieve 100k, but I plan to have some fun pushing the limits of cardboard.

 

[MClark]

I changed my mind and have new info for this thread.

1. I may start this project with hardware.

2. I discovered something very cool. RCS sells motor grains and all the parts to make motors. While I do not endorse any form of EX work in an apartment, one could easily buy the parts and assemble the hazardous parts on the field. So I am fine with EX motors for this challenge. (Note, using the motor tube as the primary structure or using motor tube components kinda defeats the point, but if you use RCS or Loki parts, it is fine.)

3. Lake Winnipesaukee! I flew there this winter and it is the Black Rock of the East when frozen. They may get a 25k ft waiver too, but that is not certain. Either way, for a narrow window in time, it is a place to test extreme projects.

I still have a LOC Magnum on order for 98 mm motors and they have the Laser Loc 3.1 in stock. Both of those are good "apartment style" builds that I can push the limits on. I do not think I will ever achieve 100k, but I plan to have some fun pushing the limits of cardboard.

You have never been to Black Rock.

 

[AlexBruccoleri]

You have never been to Black Rock.

I have not flown there but I have been there. Anyway, what are you trying to say?

 

[MClark]

Lake Winnipesaukee New Hampshire is tiny compared to Black Rock and is surrounded by houses and trees.
Unless there is another lake of the same name.

 

[AlexBruccoleri]

Lake Winnipesaukee New Hampshire is tiny compared to Black Rock and is surrounded by houses and trees.
Unless there is another lake of the same name.

You are correct it is tiny compared to Black Rock but it is large compared to almost anything else in the East. It is a good place to test stages and sub systems for more extreme projects. It is NAR though so no EX and the gentleman running the launch is making it private. I am not sure on rules but he has stated he only wants extreme projects due limited time etc.

 

[Grog6]

Thanks!

I'll share one piece of information. The attached graph is the correction the system made in the 3 stage flight (correcting from nominally 6° to about 1.5°. That made a big difference in the recovery distance. One thing that I have learned is that the canards create quite a bit of torque on the air frame. The oscillations in the tilt in the graph are due to air frame flexing and not changes in the control. On my test rocket, I applied carbon to a fiberglass aif frame to try to limit that bending, and the torgue can prevent parts of the rocket from separating. This issue would likely prevent the use of my three-stage approach on a weak rocket - there just isn't enough time in a coast to make a significant change in direction. If canards were used at the top of a weak rocket, it would be necessary to use small canards and small control actions to avoid tearing up the air frame. The idea would be to just keep slowly working back towards vertical over a long period. But, there is the weight penalty of keeping a system attached for an entire flight.

I did the two-stage flight in the video below a few years back. The stabilization system was on top of the rocket. The flight was two M motors, but the velocity was below Mach 1 for the entire flight. It only went to 23K though, and it's really hard to envision how to scale this up to 100K. Incidently, you can see the air frame flex I mentioned in the video (before I applied carbon to the rocket). That would be a real problem for a weak rocket.

Jim


View attachment 500405

I've worked with PID controllers, and have designed a few. I would analyze the data to find the frequencies of these oscillations, and figure out the loop that's taking that much time, and work it from there. a simple processor oscillator change might make it go away. You really do need all three loops to make it maximally stable.

 

[AlexBruccoleri]

I've worked with PID controllers, and have designed a few. I would analyze the data to find the frequencies of these oscillations, and figure out the loop that's taking that much time, and work it from there. a simple processor oscillator change might make it go away. You really do need all three loops to make it maximally stable.

That is a good thought. I am rusty on my control theory though, but a cardboard rocket to 100k will likely require a guidance system. I am not likely to push this concept too far and designing a guidance system would be a big task. I would be delighted to see others give it a go though. For my own builds, I may try a two-stage cardboard rocket in the next few years. That is doable with my time allotment for hobby rockets and it would be a nice excuse to fly at Black Rock.

 

[SMR]

FWIW, the original concept is a point worth exploring. What IS the limit for the majority of us, with average building skills and off-the-shelf components.

 

[jqavins]

In post #1, you stated among the rules that only TRA certified motors would be allowed. Why, when NAR and CAR certify many motors; in particular, the whole CTI catalog is CAR certified, not TRA. I see that now you're talking about research motors, so I guess perhaps it's moot.

A few times you've used the phrase "Tripoli-style rocket" or "Tripoli-style project"; what does that mean? If you only mean HPR, that's redundant given the goal.

Finally, you've mentioned "the edge of space" a few times as well. By what criterion is 100k feet the edge of space? The Karman line is at 100k meters, about 328k feet. Of course that's not the only definition of the edge of space, but all the others I've seen are higher except for the US air force definition of 50 miles, 264k feet. At 100k feet you're somewhere in the middle of the stratosphere.

 

[AlexBruccoleri]

In post #1, you stated among the rules that only TRA certified motors would be allowed. Why, when NAR and CAR certify many motors; in particular, the whole CTI catalog is CAR certified, not TRA. I see that now you're talking about research motors, so I guess perhaps it's moot.

A few times you've used the phrase "Tripoli-style rocket" or "Tripoli-style project"; what does that mean? If you only mean HPR, that's redundant given the goal.

Finally, you've mentioned "the edge of space" a few times as well. By what criterion is 100k feet the edge of space? The Karman line is at 100k meters, about 328k feet. Of course that's not the only definition of the edge of space, but all the others I've seen are higher except for the US air force definition of 50 miles, 264k feet.

If your post is directed to me I can try to respond. This was just a thought experiment to flush out ideas. The point of this is to see what altitude can be achieved with fairly accessible materials, tooling and skills. Also 100k feet is a lot easier than 100 km. While not "space" there is almost no atmosphere there and the views are pretty good.

Maybe another way to phrase my "challenge". What are the limits of rocketry when you exclude composite lay-ups, custom machining, casting propellant grains etc.? Also note I have nothing against advanced techniques in hobby rocketry. I am curious what more average skills can do though.

 

[CoyoteNumber2]

In post #1, you stated among the rules that only TRA certified motors would be allowed. Why, when NAR and CAR certify many motors; in particular, the whole CTI catalog is CAR certified, not TRA.

Those three organizations have reciprocal certification agreements. Any motor tested and certified by one is certified amongst all three.

 

[Handeman]

Sounds like a two stage with CTI O8000 motors and fiberglass MMT, BT and Nose cone would be the general theme here. I have no idea if a rocket like that can hold up to those motors, but the motors and cases are commercially available and I assume the MMT, BTs and Nose cone would be too. Might be an interesting build for someone that can afford the motors and cases on top of the remaining parts.

I usually describe rocketry like fishing, $20 for a pole and worms and sit beside a creek to $1,000,000 for a boat to fish the gulf stream. This sounds like a gulf stream project in a $500,000 boat without an experienced captain.

 

[AlexBruccoleri]

Sounds like a two stage with CTI O8000 motors and fiberglass MMT, BT and Nose cone would be the general theme here. I have no idea if a rocket like that can hold up to those motors, but the motors and cases are commercially available and I assume the MMT, BTs and Nose cone would be too. Might be an interesting build for someone that can afford the motors and cases on top of the remaining parts.

I usually describe rocketry like fishing, $20 for a pole and worms and sit beside a creek to $1,000,000 for a boat to fish the gulf stream. This sounds like a gulf stream project in a $500,000 boat without an experienced captain.

The O motors from CTI certainly have a lot of potential. Try making a sim.

 

[jqavins]

Maybe start with an O8000, coast as high as practical, then stage to one of the remaining O25000s. Or three stage O4900-O4900-O25000 for that much more impulse but lower speed in the thick air. I believe the technical term is "Thataway" "Yowza!"

 

[AlexBruccoleri]

I started work on this....Not much progress but I have a 5.5" LOC kit with a 98 mm motor in the works. The fins are on with 4 different different glue attachments. JB weld along the majority of the bottom edge with 5 minute to "tack" attach on the edges. A slight bit of 15 minute as a fillet to keep the fins in place when rotating for further attachments. I poured West System with thickener on the inner edge to the 5.5" airframe and on the motor tube to fin. I attached the rear locking centering ring, motor retainer and then applied outer filets with thickened West Systems epoxy. The outer filets are large, maybe 2 inch radius or so.

The nose cone is done and I have a design for the ebay and upper tubes worked out. My plan was to fly it on an M750 on Lake Winnipesaukee. Unfortunately I got sick and sanding outside is out of the question. I may have wait until the spring to fly it somewhere else. I also finished a Laser LOC 3.1 without any fiberglass, similar build as this rocket. I can at least fly it on a K550 and see how it holds up.

In SIM-land, I found an N2000-N1000-Loki-L1040 gets to 100k with 5.5" tubes then a 3.1 for the sustainer. Maybe I made a mistake somewhere, but intuitively that seems about right.

I am also working on some fiberglass rockets to get more experience with staging.

If my flights work out I can try a two stage 5.5" rocket. That is a big jump from what I am building currently. Right now I am just trying to build kits with solid joints. Future rockets will need to be custom designed.

Some of my post is likely repetition from past posts so apologies if you are seeing something twice.

 

[CoyoteNumber2]

In SIM-land, I found an N2000-N1000-Loki-L1040 gets to 100k with 5.5" tubes then a 3.1 for the sustainer. Maybe I made a mistake somewhere, but intuitively that seems about right.

Would you indulge us with the time vs. velocity plot?

 

[AlexBruccoleri]

Attached

 

[jderimig]

Very nice, I think a 5.5" tube should be able to handle a ~600N compressive force. A little bucking factor of safety calculation would be nice along with a test. It should be hard to apply a compressive load on a tube mockup. Anyone in your family weight 125 to 150 lbs?

 

[AlexBruccoleri]

Very nice, I think a 5.5" tube should be able to handle a ~600N compressive force. A little bucking factor of safety calculation would be nice along with a test. It should be hard to apply a compressive load on a tube mockup. Anyone in your family weight 125 to 150 lbs?

Good thought. Why only 600N? The region below the second stage will be close to 1500N, at least I think.

 

[jderimig]

Good thought. Why only 600N? The region below the second stage will be close to 1500N, at least I think.

Oh, I just quickly looked at the plot you posted and grabbed the peak that I saw. At max Q while you accelerating there will be a load gradient along the airframe, the value at the thrust plate will be your motor thrust and the nosecone end will be your drag. Hard to simulate that statically so using the motor thrust for your test and FS calc would be nicely conservative.

 

[AlexBruccoleri]

Oh, I just quickly looked at the plot you posted and grabbed the peak that I saw. At max Q while you accelerating there will be a load gradient along the airframe, the value at the thrust plate will be your motor thrust and the nosecone end will be your drag. Hard to simulate that statically so using the motor thrust for your test and FS calc would be nicely conservative.

Agreed the motor thrust is nicely conservative. It is worth noting the booster section on my rocket with a motor mount is only 5 pounds. I could easily double wall this entire rocket and keep the mass low. Paper has some real advantages It is worth noting that a lot of the composite rockets are over-engineered.

The biggest issue I see on the sim is the sustainer velocity. It is over Mach 3. I always paint my plywood with West Systems epoxy to seal them, but I suspect that is an issue.

 

[jderimig]

Agreed the motor thrust is nicely conservative. It is worth noting the booster section on my rocket with a motor mount is only 5 pounds. I could easily double wall this entire rocket and keep the mass low. Paper has some real advantages It is worth noting that a lot of the composite rockets are over-engineered.

The biggest issue I see on the sim is the sustainer velocity. It is over Mach 3. I always paint my plywood with West Systems epoxy to seal them, but I suspect that is an issue.

Epoxy can make for a nice ablative, mix a little finely powdered cork flour in the epoxy coating and you will have a very nice ablative.