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.

JimJarvis50

Well-Known Member
Joined
Jan 17, 2009
Messages
2,881
Reaction score
1,770
I've mentioned this a few places already, but my Balls project this year will be a three stager. I would normally do a thread on a rocket after I fly it. But, the chances that this flight will actually occur and be 100% successful are pretty low. So if I do a thread in advance, at least I get to document the project. It's also likely that this group might spot some things I can do to improve the odds. The thread will just describe the rocket, the prep, the flight, and ??? (to be determined later).

This rocket isn't what you would end up with if you designed at three-stager from scratch. Instead, the rocket is a recycled-yet-again combination of my FourCarbYen and TooCarbYen rockets that I flew at LDRS and Balls last year. The after-the-fact flight reports on those flights were here:

https://www.rocketryforum.com/showthread.php?58733-Balls-2013-Personnal-launch-report-Jarvis
https://www.rocketryforum.com/showthread.php?56717-LDRS-32-Personal-Launch-Report-Jarvis

But, there have been lots of changes and problems to solve, and I never really did document the designs of either of those rockets. Three guesses on the name of the new rocket?

The first pic below shows a diagram of the rocket. Some of you may recall that I enlarged (crowned) the first stage fins to increase the stability. The upper and lower diagrams show how this affected the initial stability. I've seen a few three-stagers come off the rail and start sky-writing. I'd like to avoid that.

The motors for the flight will be the CTI N5800, the CTI N2501 and the Gorilla M745. Still Class II, but not by much. I hope that helps to get the flight approved (the first potential fatal flaw for the flight). I've been warned that I will need to have tiltometers (or the like) on both upper stages - which I have - and that the angle settings will be very restrictive (the second potential fatal flaw for the flight).

The second pic shows my simulations for the flight (via RasAero and Rocksim). The agreement is pretty good. Overall, the plan is to drop the first stage at motor burnout. After the second stage burn, however, the speed is too high to drop the second booster right away. So, the plan is to let the second and third stages coast together and then separate them at about Mach 1.2. Thus, these two stages would be coasting together through the jet stream. I think the odds of getting to the third stage ignition point without a tiltometer abort are pretty low. Not much I can do about that until I can implement active stabilization.

Anyway, that's the project. With the right weather and some luck, it could work, so help me out with some ideas, OK?

Jim

Comparison.jpg

Simulations Pic.jpg
 
Jim I am looking forward to this. One idea I want to throw in is shorten the lengths of the tubes as much as possible.

You clearly mentioned that you have seen some sky writing. I believe this is mostly due to not enough railing and very long rockets.


Alexander Solis

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

Have you considered active stabilization for the flight? This would keep you vertical. The hardware to do this is now off the shelf and inexpensive as it is used for stabilization of RC aircraft.

Bob
 
I will be watching. This is going to be very cool.


Sent from my iPod touch using Rocketry Forum
 
Jim,

Your projects are one of the things that make this hobby so cool.

By this I mean that, while being into rocketry is ostensibly about "flying rockets", it's of course much more than that. If it was all JUST about flying, I myself would probably lose interest pretty quickly. Also the actual time spent flying is a pretty small percentage. The rest of the time I'm "doing rocketry" (meaning the bulk of it) is spent designing, building, planning, (purchasing bits!), dreaming......and sharing everyone else's experience, either at launches or here online. I get SO much enjoyment/thrill/education/fun from seeing what all the rest of the forum is building and flying. The wealth of information, high level of craftsmanship, crazy and cool experiences, and simple joy of being involved in this hobby are amazing here on TRF. And your projects are often at the very pinnacle of what's presented here.

So thank you for sharing so much of what you do. And thanks for really pushing the envelope in terms of performance and craftsmanship. You've absolutely made this hobby that much better for all of us. Good luck with this latest challenge.

Yeah, I'll be watching this thread.

s6
 
Last edited:
Jim I am looking forward to this. One idea I want to throw in is shorten the lengths of the tubes as much as possible.

You clearly mentioned that you have seen some sky writing. I believe this is mostly due to not enough railing and very long rockets.


Alexander Solis

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

I could shorten the 2nd stage a few inches, but that's about it. I'll verify that before too long. If it's only a few inches, I'm not sure that would help much, and there's another reason I don't want to do this (a funny story I'll include when I get to that part of the rocket). If it's more than a few inches, maybe I'll do it. I have a stabilized 16' rail and the initial acceleration is in the range of 12 G's. It should be fine as long as the various joints are strong and the overall stability is OK.

Jim
 
Jim

Have you considered active stabilization for the flight? This would keep you vertical. The hardware to do this is now off the shelf and inexpensive as it is used for stabilization of RC aircraft.

Bob

I'm hoping Random Flying Object will share his secrets with me. I really would like to do this, and I suspect it will be a requirement for Tripoli approval before long.

Jim
 
Cool project, Jim! If, by some miracle, I'm at the launch when this flies, you can count on me to be a pad slave.

Have you considered something a bit smaller in the first stage? I suspect keeping it below Mach while that stage is on would reduce stress on things quite a bit. Obviously, it'll cut down your velocity and altitude, but it should help with reliability as well.

-Kevin
 
Cool project, Jim! If, by some miracle, I'm at the launch when this flies, you can count on me to be a pad slave.

Have you considered something a bit smaller in the first stage? I suspect keeping it below Mach while that stage is on would reduce stress on things quite a bit. Obviously, it'll cut down your velocity and altitude, but it should help with reliability as well.

-Kevin

Although I agree with it being less stress, I would be concerned that would result in a less than ideal boost phase for the first stage (in terms of being close to 90 degrees alpha). I think it is already going to be difficult to stay within the angled criteria for sustainer ignition… that would seem to make it even harder. The booster has a lot of weight to boost.
 
Last edited:
Cool project, Jim! If, by some miracle, I'm at the launch when this flies, you can count on me to be a pad slave.

Have you considered something a bit smaller in the first stage? I suspect keeping it below Mach while that stage is on would reduce stress on things quite a bit. Obviously, it'll cut down your velocity and altitude, but it should help with reliability as well.

-Kevin

Kevin, you were a wonderful pad slave! I really hope that you can make it. I was going to discuss this later in the thread, but figuring out how to safely raise this rocket and then arm it has been the most difficult part of the plan so far. I believe I have this worked out, but there is room for improvement.

Relative to the pic below, the piece that holds the guide wires is now placed at the top of the rail (need some place to set the ladder to be able to access the third stage electronics). The whole setup - rocket and rail - is about 220 lb, and the weight distribution is less favorable than before. We've tested this and it can be done, but there is more to it than just hoisting it up.

Jim

LDRS32-153005 Crop.jpg
 
I believe I have this worked out, but there is room for improvement.

What have you decided on? If you recall I suggested for you to use a mounted winch. 220lbs is not that much weight especially if you have a couple people willing to help out. Now arming the electronics is another story… but getting it vertical I think is the easier of the two.

I would suggest maybe holding your breath when you are up at the top of the tower trying to arm the 3rd stage. Holding your breathe will prevent you from passing out (due to the thin air) and falling to the bottom. If need be, I can provide you with some breathing air… I have cylinders filled with the stuff. Helium, Oxygen up to 100%, and mixtures also. Take your pick!

Mat
 
Last edited:
I'm hoping Random Flying Object will share his secrets with me. I really would like to do this, and I suspect it will be a requirement for Tripoli approval before long.

Jim
We've had several recent threads on flying straight up on TRF. Alyssa Stenberg's NARAM 55 R&D report on using the Eagle Tree Guardian https://www.eagletreesystems.com/Manu...an%202D-3D.pdf as the stabilizer to move forward canard fins or gimbaled motors.

https://www.youtube.com/watch?v=A4M9Uso9EsY is a video of her presentation. The presentation and the results are impressive.

References.

https://www.rocketryforum.com/showthread.php?51513-Fly-Straight-Up

https://www.rocketryforum.com/showt...cket-motor-works-pretty-well-on-model-rockets

Bob
 
We've had several recent threads on flying straight up on TRF. Alyssa Stenberg's NARAM 55 R&D report on using the Eagle Tree Guardian https://www.eagletreesystems.com/Manuals/Guardian 2D-3D.pdf as the stabilizer to move forward canard fins or gimbaled motors.

https://www.youtube.com/watch?v=A4M9Uso9EsY is a video of her presentation. The presentation and the results are impressive.

References.

https://www.rocketryforum.com/showthread.php?51513-Fly-Straight-Up

https://www.rocketryforum.com/showt...cket-motor-works-pretty-well-on-model-rockets

Bob

I'd be worried about control reversal or other unintended effects when supersonic and using canards for guidance. Have these systems been used above Mach?
 
Last edited by a moderator:
I'd be worried about control reversal or other unintended effects when supersonic and using canards for guidance. Have these systems been used above Mach?
On every air to air missile.......

Bob
 
What have you decided on? If you recall I suggested for you to use a mounted winch. 220lbs is not that much weight especially if you have a couple people willing to help out. Now arming the electronics is another story… but getting it vertical I think is the easier of the two.

Mat

Here's the current lifting plan. Please let me know if you see any flaws or ways to improve this. If I can't make this work, there's no flight.

The pad I'm using has a clamshell design (per the pic). It's pretty heavy. The center of gravity of the rail and rocket is about 9 feet up the 16-foot rail. This point would be about 12' off the ground when the rail is raised. So, considering the lever arms, the guy on the clamshell "rod" can "lift" about 30 lb of the 210 lb load (I checked, it's 210 lb) by pulling at 60 lb 5 feet up this rod. A guy "walking" up the rail can probably account for another 30 lb (by pushing at 60 lb halfway to the center of gravity). That leaves 150 lb unaccounted for.

What I think will work is to have a pole attached at the center of gravity. The concept is in the second pic. The point of attachment is at the 9' point on the rail (i.e., at the center of gravity). The idea would be to have 3 strapping pad slaves lift the rail so that the "T" pole is a little off the ground and hanging vertically. Then, two more strapping pad slaves would lift 75 lb each at the T pole, moving towards the pad a bit, until the handle was about 5 feet off the ground. At that point, most of the weight is off, and you just move it to vertical. We've tested this with the rail only, and it's fairly easy to do (although it is unnerving because there is a lot of rail up there and it moves a bit). With the rocket, the weight would double.

I don't see a good way to use a winch on this. If you were to attach a winch to the clamshell rod, without also lifting the rail, then the rail just bends at the point where it's attached to the pad. And, a winch attached near the center of gravity of the rail doesn't have much mechanical advantage and puts a lot of torque on the rail. Maybe I'm overlooking something there?

Jim

Clamshell.jpg

DSCF0802.jpg
 
That was pretty much what I was thinking except once it is slightly raised via someone (or someones lol) then the winch would pull it the rest of the way up. You would want to make sure that the launch rail is secure when doing so, to not have any play. When I see you this Saturday I will draw it out for you and show you where I would have the attachment points.

I think your method will work fine. Just requires a couple of people who think they can bench press some rockets. You can count on me to help you at BALLS… they say slavery is dead… apparently not in NV.

Mat
 
The one you linked?
No, not the particular one I linked, however it has be used to stabilize hobby rockets.

Control reversal was caused by shock generation by hinged control surfaces, not the control systems. The use of flying tails, aka a stabilator, eliminates the control reversal. Flying Canards are examples of a stabilator.

Bob
 
Jim , what about doing a N10,000 in the booster staged to a O3400 to a M745 .

Eric

The order must be 98-something to CTI 98-6 to AMW 75-6000. I'm not really all that worried about having the stack go through Mach. All of my previous 2-stage flights have done that. I am a bit worried about having the second stage go to Mach 2, but even an N-1100 gets close to that.

Jim
 
That was pretty much what I was thinking except once it is slightly raised via someone (or someones lol) then the winch would pull it the rest of the way up. You would want to make sure that the launch rail is secure when doing so, to not have any play. When I see you this Saturday I will draw it out for you and show you where I would have the attachment points.

I think your method will work fine. Just requires a couple of people who think they can bench press some rockets. You can count on me to help you at BALLS… they say slavery is dead… apparently not in NV.

Mat

OK, we'll kick it around some. Thanks for the help!

Jim
 
The order must be 98-something to CTI 98-6 to AMW 75-6000. I'm not really all that worried about having the stack go through Mach. All of my previous 2-stage flights have done that. I am a bit worried about having the second stage go to Mach 2, but even an N-1100 gets close to that.

Jim

I think your current course of action is just fine. That is, keeping the 2nd and 3rd stage together until they slow down some before separation.
 
So, here's some information on the first stage. This is an interesting rocket. It is one of the worst tubes I ever produced, but it has been a very successful rocket (having flown on 10 N motors to date).

One main thing that I changed on this rocket for the three-stage flight was to add the fin "crowns", which were discussed in this thread:

https://www.rocketryforum.com/showthread.php?63099-Perhaps-my-Crowning-Achievement

I feel much more comfortable with the extra stability that these provide.

The airframe on this rocket is a bit larger than minimum diameter (it was rolled on an "airframe" mandrel). Thus, the coupler is actually airframe tubing, which allows the motor case to fit up into the coupler to about the position shown in the pic. Thus, the coupler is pretty strong, which is helpful because this part of the rocket sees a lot of stress.

The altimeter bay was originally designed to slide into the top of the airframe and then rest on a bulkhead inside the tube (i.e., no tube break). The sustainer for the FourCarbYen was an actual minimum diameter airframe, and the airframes for these two stages didn't match up very well. Therefore, I added a ring inside the top of the airframe for the sustainer motor to sit on, and this ring is the point where thrust is transferred to the upper stages. Unfortunately, it was now no longer possible to insert the altimeter bay into the airframe. To solve that problem, I modified the altimeter bay to remove the normal outer casing and I reduced the diameter of the bulkheads so that the bay could be inserted, just as shown in the pic, through the smaller thrust ring. The gas seals to protect the altimeters from the charges are via the O-rings (to the bulkhead on the bottom of the bay and to the airframe on the top of the bay).

When I started flying 98mm sustainers, I decided to reinforce the upper part of the airframe. This airframe was originally only 5 wraps of 6 oz carbon, and I didn't think that this would be strong enough to support a 98mm sustainer. So, I added an additional 5 wraps to this part of the tube. Other than the fin crowns, though, the only change in this booster for the three stage flight is the added rail button at the top of the airframe.

Like I said, you would never design a rocket this way starting from scratch, but this rocket just seems to keep on getting the job done.

Jim

DSCF0800.jpg

Ebay PNG.jpg
 
If I may ask, how many dollars worth of motor is that flight looking like it'll be? :eek:
 
Jim

the two stage at LDRS XXX - did you ever locate the sustainer? In my sleep deprived fog, I though I remember that it staged successfully then disappeared.
 
If I may ask, how many dollars worth of motor is that flight looking like it'll be? :eek:

Keeping in mind that I only do this once a year (OK, twice sometimes) ....
And keeping in mind that I will probably have motors left over after this flight (sadly) ....
And keeping in mind that motor vendors sometimes feel sorry for me (but not sorry enough) ....
And that my wife enjoys our trips to BlackRock (but would never admit it) ....
And that the cost of the motors is a relatively small fraction of the total cost :)y:) ....

Lemme see. Retail looks to be a bit over $2K.

Over time, I've heard a number of estimates of what it would cost for a project over 100K feet. I spend much less than those estimates, but it will never be cheap.

Jim
 
Over time, I've heard a number of estimates of what it would cost for a project over 100K feet. I spend much less than those estimates, but it will never be cheap.

Jim

Out of curiosity, what are those estimates?
 
Back
Top