So, maybe I'll try a three-stager

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
I was reading this over and thought of a building technique from fiberglass boats. They faced all the same issues you do, plus EPA clamping down on the VOCs coming off polyester resin. There are a couple of different patented approaches, but they all basically add resin after the vacuum is pulled on the cloth. As I understand it, they lay out all of the layers of the cloth, pull down a vacuum, then open up valves between the part under vacuum and a reservoir of resin. The tricky part is knowing how far the resin will flow before it starts setting up to make sure that you wet out all the fabric completely. A description of the one of the patented versions is here: https://www.boats.com/how-to/scrimp-system/

I have no idea if this would work for thin-walled carbon tubes, but it might be worth experimenting with if you have some extra carbon fiber cloth hanging about. Or you could just send that extra cloth to me. :)

What you're talking about is resin infusion, and here's an excellent tutorial:

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

One day... one day.
 
Well, it's been quite a while since I updated this thread. As a reminder, this thread is temporarily a P to O two-stager for Balls this year that will go back to a three stager next year if I still own the rocket.

I've been doing quite a bit of work on the rocket. The sustainer is pretty much done. The main accomplishment on that has been the AV bay, which is done and fitted into the rocket. My bays are not works of art (I had to wait a while before posting to let memories of Eric's bay fade a little). But, it's functional and there is a lot of stuff packed into not too big of a volume.

I've also spent a lot of time on the various "connections" between the sustainer, the stabilization spool and the staging transition. I was also hoping to conduct one more test flight of the stabilization system on my two-stage test rocket (a complicated flight in its own right). So, all of the pieces and keys between the parts had to be made to fit for both the test rocket and the Balls rocket, and for the Balls rocket, with and without the stabilization spool. Getting all of the configured has been a real brain teaser.

I have also been working up the Class 3 paperwork and all of the associated simulations.

And then I ran into a problem (to be continued) ....

Jim

IMG_0798.jpg

IMG_0800.jpg

IMG_0801.jpg

IMG_0804.jpg

IMG_0805.jpg

IMG_0806.jpg
 
Jim, a problem? Waiting on that.

I've been doing this staging stuff for a few years now, so you might think I have some clue as to what I am doing. The design always starts with a simulation, and then the simulation is a critical part of the construction and then the flight itself. Imagine my surprise when I realized that I missed the proper simulation result on this flight by a paltry 100K. How did I manage this feat? Well, in RasAero, there is more than one way to produce the shape of the rocket (with the 6" by 4" transition). One way is to build the sustainer, add a transition and then add a booster. The second is to build the sustainer, add a booster, and then specify the shape of the transition for the booster. Only the second way is correct. When you do it the first way, all of the simulations are with the transition still attached to the sustainer. As Rick Perry put it so well..., oops.

I finally figured it out when I tried to model the rocket as a three-stager, with the stabilization spool as the second stage. I'm not quite sure on the first attempt at this if the transition was associated correctly with the first stage, or if it was part of the stabilization spool, but the important thing was that it was no longer part of the sustainer. All of the sudden, things stopped making sense, and after looking at CDs, drag, frontal areas, etc., I figured it out.

I was thinking that this flight would go to something like 180K (the simulated result, with an actual altitude of 160K or so). Nice flight! The new simulation, however, is 290K. That would be good, except that I'm not sure such an altitude can get Class 3 approval, the speed is much higher (Mach 3.6, albeit at 50K), the rocket would likely be doing cartwheels for the last 100K, and it may not be physically possible this year to get to the location where we would have to go to launch to this altitude. Details.

So, we need a Plan B. Turns out I have another motor in hand that would get things back in the range of the original simulation. The problem is that the stabilities of the various configurations is kind of a fine balance, and changing the motor affects everything. I'm still looking at this, but I think one thing that will be necessary is to add some wing tips to the booster fin can. I did this on the three-stager booster last year. Adding 1" to the span takes the initial stability from 1.4 to 2.4 calibers, which I think is about right. That will force a change in the pad design, and so it goes. At least I figured it out before the Class 3 guys "brought the issue to my attention", and perhaps too late to fix.

One other minor issue is that the smaller motor is the one that I was planning to use for one final test of the stabilization spool. That's a flight that I tried a few months ago. That flight uncovered a software bug (a good thing) but fell short on other objectives. With Plan B, I don't have a motor to try it again.

I will now retreat to my cave, hoping that it will be at least another few years before I do something like this again.

Jim

IMG_0654.jpg
 
Jim, Black Rock can support that if memory serves. I would urge you to consider the original plan and motors. I would also consider contacting Kent Newman, and "bouncing" the sim off of him to make sure his take and your take jive. I believe the 90 day window would be fast approaching.
 
Last edited:
Jim is the exact sequence of assembling multistages spelled out in the RASAero manual. If not, don't see how you can blame yourself. Specifying the transition last certainly doesn't seem intuitive. But at least you got an "upside surprise." Better than the other way around.
 
Jim, Black Rock can support that if memory serves. I would urge you to consider the original plan and motors. I would also consider contacting Kent Newman, and "bouncing" the sim off of him to make sure his take and your take jive. I believe the 90 day window would be fast approaching.

I think part of the problem is that the additional speed puts the sustainer unstable (If I understand Jim's text correctly) - the solution to that would be bigger sustainer fins, which would require bigger booster fins and a bunch of knock on effects.
 
Jim, Black Rock can support that if memory serves. I would urge you to consider the original plan and motors. I would also consider contacting Kent Newman, and "bouncing" the sim off of him to make sure his take and your take jive. I believe the 90 day window would be fast approaching.

Kent has all of the data. I think that BlackRock can support the altitude (up to around 350K now I believe). However, the closer to that altitude that you are, the closer you need to be to the BlackRock Center Point. Unfortunately, the Center Point is in the middle of the Quinn River basin, and my understanding is that this year, you would need a camel to get there. I'm not exactly sure how suitable launch locations will be established. It's possible something to the south of the Center Point could be reached, but I don't think the flight could be done from the Balls launch site itself.

At this time, all I can do is to try and keep options open for all of the various alternatives. I was considering shortening the sustainer for the shorter motor, but I am now leaning against that.

Jim
 
Jim is the exact sequence of assembling multistages spelled out in the RASAero manual. If not, don't see how you can blame yourself. Specifying the transition last certainly doesn't seem intuitive. But at least you got an "upside surprise." Better than the other way around.

Well, the obvious questions is, what would you do if you did want the transition to stay with the sustainer. Hmm. The manual does include an Example 3 that is a rocket with a transition, so an option would be to read all of the directions. It would help to avoid dumb mistakes to have diagrams of both the stack and the sustainer alone, as RockSim has. But otherwise, it's on me.

Jim
 
I think part of the problem is that the additional speed puts the sustainer unstable (If I understand Jim's text correctly) - the solution to that would be bigger sustainer fins, which would require bigger booster fins and a bunch of knock on effects.

The stability issue is with the stack early in the flight. The alternative motor is an N3180, and the difference in the weight of the motors is substantial. It just isn't feasible to add weight to the sustainer nose cone, for example, as I don't want it to be too over stable for use with the stabilization spool. And, you couldn't add enough weight in the transition coupler area to make a difference. The only option that makes sense to me is to make the booster fins a little larger.

The speed of the flight was still pretty high, even with the transition attached (like Mach 3.4 I think?). So, the rocket was designed to be stable. The graph below has the CG/CP during the sustainer burn with the O3400. I think it's OK. But, in this speed range, every tenth of a mach number is important.

Jim

CG_CP.jpg
 
Jim, this is a really extreme flight. My suggestion is to make sure all ducks are in a row before flying. Meaning that if you are not sure I would rather see you take the time to be sure it is right even if that means not flying it this year. I know- the extreme view of things
 
Jim, this is a really extreme flight. My suggestion is to make sure all ducks are in a row before flying. Meaning that if you are not sure I would rather see you take the time to be sure it is right even if that means not flying it this year. I know- the extreme view of things

Even with the change in the plan, we will be done several months in advance. There's no reason to stand down. I'm OK with the options we have. We'll talk to a few adults and then pick one (although comments on the plan are welcome).

Jim
 
Even with the change in the plan, we will be done several months in advance. There's no reason to stand down. I'm OK with the options we have. We'll talk to a few adults and then pick one (although comments on the plan are welcome).

Jim

Seems reasonable to me. I was just suggesting, as I am sure you realize, that it is ok to step back from the flight if you were not reasonably certain things will work.

I did not think you were bitten by the go fever bug. If you want my input on the sims shoot me a pm- happy to look if you want another set of eyes.
 
Even with the change in the plan, we will be done several months in advance. There's no reason to stand down. I'm OK with the options we have. We'll talk to a few adults and then pick one (although comments on the plan are welcome).

Jim

Please remind me never to post anything like what I said above again. Just a few shorts months ago I said those things. And now:

- "A change in the plan". Have been several more since.
- "Done several months in advance". Still scrambling.
- "Talk to a few adults". None showed up.

Let's see, where to start. First, as a reminder, this is the rebuild of the second stage of my three-stager, which was lost at Balls last year. This year will be a diversion to a P to O two-stager, with the three stager to follow if I still own the rocket. The good news is that the P motor grains are done. A few of them had to be redone due to a curative problem, but all is good now. It's an 84% P7235. Other good news is that all data has been submitted to the FAA. We're optimistic for approval.

Most of the scrambling has been trying to figure out how to get the pieces of the rocket to fit together, to be loadable on the pad and to be able to raise the rocket when the time comes. The rocket and rail come in at 350 lb. It's not a trivial process to get it loaded and raised. I'll post more on that over the next few days.

The other scrambling has been with the O motor. For reasons unknown, the HTPB used to glue in the grains did not set up. It was quite well stirred, cause I know what you're thinking, but it only got to a nice semi-solid-liquid goo like the stuff you find in the sticky mouse traps. I figured it out when I inverted the liner and a grain moved. Hmm. Over the next couple of hours, they all plopped out. Not what you want to see with your O motor. This will take some more explanation, but fortunately, the folks at CTI have taken pity on me and I think we have a good plan for salvaging the motor. I'll find out this weekend if it's a P to O or a P to N.

I'll post a few pics over the weekend since it's been a while. For now, here's a not-so-good pic of Stu and the rocket from a recent rail-fitting exercise.

Jim

IMG_0856.jpg
 
Jim, that is an impressive looking beast...the rocket not Stu.

I assume the rail pivots from the bottom?
 
Jim, that is an impressive looking beast...the rocket not Stu.

I assume the rail pivots from the bottom?

I'll pass that comment along to Stu!

OK, starting with the pad, yes, it pivots from the bottom. A clam shell design.

The first and second pics below show how we have raised rockets in the past. The idea was to lift the rocket to the position shown, and then insert an 8-foot 2x4 to hold it in position. Then, it was lifted to vertical using a winch. It is quite easy to do both operations as it turns out.

This year, the rocket weighs 100 lb more. I'm sure a select group of pad slaves could lift it, but I don't have them. So, I have added a lever arm to the pad, made with 1/4" angle iron, so that there can be at least some winch-assist starting from horizontal. The pad is pretty heavy and it will be staked down, but the horizontal force will increase. So, some testing will be required to figure how best to use this. It would be nice if the rocket could be lifted with no one in the area.

Jim

20140920_103513.jpg

Geometry2.png

Geometry3.jpg

IMG_0875.jpg
 
Jim,

I believe I asked once about the extremely long tubes. You stated there was a reason for this, but did not mention it or maybe I missed it.

Oh and I'll take those motor casings lying on the floor if they are going to be treated like that lol.


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 
Jim,

I believe I asked once about the extremely long tubes. You stated there was a reason for this, but did not mention it or maybe I missed it.

Oh and I'll take those motor casings lying on the floor if they are going to be treated like that lol.


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

What extremely long tubes?

Regarding the motor, I don't really have the infrastructure for 6" rockets and particularly not metal ones. But one thing I've learned is that if a 6" metal tube is on the floor, you can't drop it.

Jim
 
What extremely long tubes?

Regarding the motor, I don't really have the infrastructure for 6" rockets and particularly not metal ones. But one thing I've learned is that if a 6" metal tube is on the floor, you can't drop it.

Jim

I meant the tubes on the three or two stager of your design. I just see them way too long and unecessary, but you said it was for a good reason.

About the motors I meant the two lying on the floor on the picture with Stu. I believe thats a 54mm and a 38mm?


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 
I meant the tubes on the three or two stager of your design. I just see them way too long and unecessary, but you said it was for a good reason.

About the motors I meant the two lying on the floor on the picture with Stu. I believe thats a 54mm and a 38mm?


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

The tubes hold either a long motor, parachutes, or the motor of the next stage. All necessary I think. The 38mm case got there as a spacer to temporarily hold the 4" sustainer off the rail. I think it fell off though (I told you, they are safer on the ground).

Jim
 
Over the winter, I made a composite fin can for the 6" part of the rocket. One change in the plan is that we are not using it. Instead, we're back to the original aluminum fin can. It's sort of a long story. The start of it was that the P motor came out with a bit more energy than we thought. With that, and the O motor, we were getting simulations near 300K. The goal is to try to get above 200K, and maybe actually get the rocket back. So, we had a number of choices to reduce the altitude, including making the booster motor smaller (6 grains instead of 7) or the sustainer motor smaller, or to add weight. Another variable was the need to keep options open if the higher altitude flight was not approved. Yet another variable was to be as high as possible for the maximum velocity of the sustainer.

After consideration, we elected to stay with the larger motors but add some weight in the form of the aluminum fin can. This gets us a simulation in the 240's with a reasonable chance to actually break 200K (my rockets go to 85-90% of the simulation). An additional advantage is that the aluminum fin can won't shred, whereas the composite fin can might. The approach helps on the altitude problem and also eliminates one risk factor.

Not sure what will happen with the composite fin can. Probably nothing. Oh well, it only took a month, plus or minus, to make.

With either fin can, the smaller sustainer motor option, which is still a possibility, requires some additional stability shortly after takeoff. So, I've added some fin tabs to the aluminum fin can just to continue to keep our options open.

Jim

IMG_0654.jpg

IMG_0867.jpg
 
The tubes hold either a long motor, parachutes, or the motor of the next stage. All necessary I think. The 38mm case got there as a spacer to temporarily hold the 4" sustainer off the rail. I think it fell off though (I told you, they are safer on the ground).

Jim

Those must be some monster chutes and motors that occupy all that space.


Alexander Solis - TRA Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 
So, I believe I have "recovered" the O-3400 motor. Just as a reminder, this thread is the rebuild of the second stage lost last year at Balls. The flight this year will be a P to O two-stager, with the three-stager next year if I still own it.

I had a problem with the O motor. Basically, the HTPB adhesive provided with the kit didn't set up. Not sure why. The grains were wetted with the old adhesive, so the first step of the cleanup was to "peel the grains" to remove the saturated paper. That left the grains pretty loose in the liner, so the question became how to best build back up the diameter of the grains. I got lots of advice, but I ended up working with the technical folks at CTI and we devised a plan using HTLO, Papi 901 and microballoons. The microballoons thicken the HTLO and provide some thermal insulation.

The first pic showed the condition of the grains after peeling away some of the packing tube. For perspective, the gap around the grains was the equivalent of from 4 to 7 wraps of masking tape. The strategy was to first build up some tight-fitting rings on the ends of each grain. These would help to center the grains in the liner later on and keep the adhesive "contained" between the rings. Pictures help here. The first step was to build up the OD of the grains using masking tape. Then, the ring was built up with HTLO (HTLO/Papi first and then HTLO/Papi/MB) and then formed into a ring with teflon-coated mylar, flush to the end of the grain. The rings were then sanded to fit the ID of the liner.

To be continued ...

Jim

IMG_0882.jpg

IMG_0888.jpg

IMG_0889.jpg

IMG_0890.jpg

IMG_0894.jpg
 
(Continued)

To assemble the motor, the space between the rings was coated with HTLO/Papi and then frosted with the HTLO/Papi/MB mixture. I used 10% microballoons by weight. I'm pretty sure that most of the volume between the rings got filled with the mixture, and I'm happy with how it turned out. So, the plan is to fly the motor in a few weeks.

Jim

IMG_0895.jpg

IMG_0896.jpg

IMG_0897.jpg

IMG_0898.jpg
 
Sorry to hear of the loss. Awesome project though. Can't think there is much shame in shredding at Mach 3.7. Looking forward to seeing next year's build.
 
Yes, it flew, but not well. As usual, it was a complicated flight and will require some data analysis. I do have several interesting videos and lots of data. I'll post more when I'm off the road.

In the mean time, Geoff Huber posted this video.

https://photos.google.com/share/AF1...?key=NEtfTnNkb2tQV0hQc190SXJSVFFVWlA3QldDbUt3

Jim

Bummer Jim.

I see Kate was on board and @ a 100'/s touchdown I am guessing you lost some electronics and hardware. Looking forward to reading your review of the data.

But wow Mach 3.7!
 
That's a bummer. Did it shred or did the O motor CATO? Still, Mach 3.7 is awesome. Is that a personal record for you?

After seeing Kate in action, I gotta get one..
 
Back
Top