Information on multistage rockets?

[ballmill]

I'm looking for some good info on the construction of multistage rockets. I can't seem to find anything. I have and read Dave Sleeters book which is great, but he doesn't really dip into this subject.

 

A book or website would be helpful.

[Nessalco]

I'm looking for some good info on the construction of multistage rockets. I can't seem to find anything. I have and read Dave Sleeters book which is great, but he doesn't really dip into this subject.

 

A book or website would be helpful.

 

I'm not sure you're going to find much. Muiltistage rockets are fairly rare birds in the world of high power rocketry, and some of the more complex rockets that people fly. Of the 30 or so attempts that I've seen, only three were successful.

 

They are supposed to work like this: The main motor is lit on the pad as usual. As the rocket lifts off, the flight computer detects launch, then detects burnout as the thrust ends. At this point a small charge is initiated to separate the upper stage from the booster. After a calculated interval another flight computer in the upper stage lights the motor and sends it on its way. The computer in the booster manages the parachutes for the booster, and the computer in the upper stage manages the laundry there.

 

There are many failure modes. Two motors, two computers, too many problems....

 

I did a Google search and only came up with staging of model rocket (BP) motors. That is super easy, and well documented. Staging high power motors is a different kettle of fish. You need to use a flight computer of some sort, a lot of planning, and more than a little luck.

 

A couple years ago the upper stage of a two-stage rocket ignited while the rocket was horizontal, and shot into a crowd of about 500 participants. Two ended up airlifted out, and the litigation is ongoing.

 

 

Kevin

[dagabu]

I'm looking for some good info on the construction of multistage rockets. I can't seem to find anything. I have and read Dave Sleeters book which is great, but he doesn't really dip into this subject.

 

A book or website would be helpful.

 

OK, I dont want to get this wrong before we start: Are these fireworks or model rockets?

 

-dag

[ballmill]

Oops, I'm asking about fireworks rockets, mainly in the 1lb to 3lb range, both whistle and BP types.

[Ralph]

Im no skilled rocket man by any measure unlike Dag but for 1/4" and 1/2" whistles and bp rockets Ive found that if you place alittle bp on the top of the first rocket (granulated is good granulated with some meal is more forgiving) than on the 12mm I attach with one turn of making tape than with a craft knife carefully slice through 2/3-3/4 of the tape each rocket has its own individual stick ( the first one has a longer stick to compensate for 1/4" rockets I put one tiny piece of tape. The sound they make as it changes stages is amazing

 

 

Im sure there are much better methods out there but this way has worked for me and so Ive never felt the need to change it

 

heres one I prepared earlier the video really dosnt do justice to it those thinggs rattle you as they take off.

 

also note if doing whistle dont get fancy adding dragon eggs to the separation charge will result in cato after cato (extremly loud and unexpected catos )

 

 

EDIT: I wrote 1/4" twice instead of 1/4" than 1/2"

Edited June 21, 2011 by Ralph

[dagabu]

Oops, I'm asking about fireworks rockets, mainly in the 1lb to 3lb range, both whistle and BP types.

 

I dont know of a book or website that really go in depth for the same reasons that Ness gives, they are messy and usually dont work very well. I have found a fool proof way to stage my BP rockets and have done three and four stage rockets with no issues. The problem is that the sustainers are not very powerful and the whole shebang doesn't go all that high.

 

I am working on two stage whistle rockets that are fully cored where the "passfire" is a two section arrangement that separates the bottom motor and then lights the upper stage once it has no back pressure. If it works, I will do tutorial. So far, they have been nothing but interesting salutes

 

-dag

Edited June 21, 2011 by dagabu

[Nessalco]

Oops, I'm asking about fireworks rockets, mainly in the 1lb to 3lb range, both whistle and BP types.

 

Doh. Sorry 'bout that.

 

Kevin

[ballmill]

I'm sure there is a reason why this isn't the way its done but couldn't you run a passfire fuse from the delay on the first motor up to the core on the second and ignite it that way? Holding together both motors with a loose piece of kraft could keep them together during flight.

 

I'm thinking with a second whistle booster once it ignites it could cato since whistles don't like obstructions as they burn.

[dagabu]

I'm sure there is a reason why this isn't the way its done but couldn't you run a passfire fuse from the delay on the first motor up to the core on the second and ignite it that way? Holding together both motors with a loose piece of kraft could keep them together during flight.

 

I'm thinking with a second whistle booster once it ignites it could cato since whistles don't like obstructions as they burn.

 

True that, even a piece of tissue paper is enough to pop one of my whistle rockets. I will share my idea with you all if I can get it to work, hang in there, this may be a game changer!

 

-dag

[shockie]

Attached is a sketch of a 2 stage BP rocket by John Reilly, a well-known pyro. I think I got this at pyrobin. In the Best of AFN IV, there is a similar sketch showing a 2 stage whistle rocket.

 

 

What I want you to notice is to compare the length/depth of the dealy above the core when compared to the BP rocket here:

http://www.skylighte...der-rockets.asp

 

notice the thrust/delay boundary and the length of the delay. You don't want any delay.

 

Also on his attachment coupler I would place some small exhaust holes around the periphery to properly vent the BP gases and allow the BP particulates to blow upwards into the core, igniting the sustainer, before blowing off the booster itself.

 

Steve LaDuke presses hybrid whistle mix/BP mix rockets where the cored grain is whistle or strobe mix and then he presses a layer of BP. You could do something similar, or just use a clay bulkhead with passfire hole and 4 Fg (fine) BP to ignite the upper motor.

 

good luck!

 

hth

 

EDIT I forgot too add that since you will have more weight up front, the 2 stage stick should be made longer

 

Terry

Edited June 22, 2011 by shockie

[stckmndn]

Thanks shockie. That looks like it will work easily with two BP motors. And it'll only take a few minutes to put together.

[dagabu]

Attached is a sketch of a 2 stage BP rocket by John Reilly, a well-known pyro. I think I got this at pyrobin. In the Best of AFN IV, there is a similar sketch showing a 2 stage whistle rocket.

 

 

What I want you to notice is to compare the length/depth of the dealy above the core when compared to the BP rocket here:

http://www.skylighte...der-rockets.asp

 

notice the thrust/delay boundary and the length of the delay. You don't want any delay.

 

Also on his attachment coupler I would place some small exhaust holes around the periphery to properly vent the BP gases and allow the BP particulates to blow upwards into the core, igniting the sustainer, before blowing off the booster itself.

 

Steve LaDuke presses hybrid whistle mix/BP mix rockets where the cored grain is whistle or strobe mix and then he presses a layer of BP. You could do something similar, or just use a clay bulkhead with passfire hole and 4 Fg (fine) BP to ignite the upper motor.

 

good luck!

 

hth

 

EDIT I forgot too add that since you will have more weight up front, the 2 stage stick should be made longer

 

Terry

 

Full cored rockets are pretty much on the red line and are very hard to light in the role of sustainer by simple BP or black match without over pressuring the motor. Whistle motors are even harder to successfully light when cored.

 

BTW- how would you propose pressing a layer of BP on top of a UT fuel grain? I am confused by your posting.

 

-dag

Edited June 23, 2011 by dagabu

[nater]

Also on his attachment coupler I would place some small exhaust holes around the periphery to properly vent the BP gases and allow the BP particulates to blow upwards into the core, igniting the sustainer, before blowing off the booster itself.

 

I recently read this article about an easier three stage model rocket, it sounds similar to what you propose: http://www.rocketryp.../#axzz1Q6Qpk2K1

Edited June 23, 2011 by nater

[dagabu]

I recently read this article about an easier three stage model rocket, it sounds similar to what you propose: http://www.rocketryp.../#axzz1Q6Qpk2K1

 

All three ESTES rocket engines are end burners and are impervious to CATO when arranged like that. I wish I could duplicate the performance of those engines so that I could stage them like that

 

-dag

[r1dermon]

Estes fuel grains have a very short core which aids in ignition and also helps initial thrust. They're not true end burners.

[dagabu]

Estes fuel grains have a very short core which aids in ignition and also helps initial thrust. They're not true end burners.

 

After sitting through a long argument between two old snorts that claim to have known Vern Estes, it was decided by them that if the "core" was less then one ID then it was an end burner. It is their adult beverage and cigar fueled tempest in Appleton last year that leads me to believe this to be true and as the ESTES engines have a core of less then one ID, I call them end burners as well.

 

Is there an ESTES engine that has a deeper core? I am afraid that my experiences are limited to ESTES D size and under...

 

-dag

[r1dermon]

I have drilled full length cores into estes motors with varying success, though i have no apparatus to effectively measure the total/average impulse. Just remember, with a full core motor, the fuel will be consumed faster, and the delay will ignite sooner, so I've removed the burst charge on the motors. Reliable ignition can be attained by utilizing a really thin piece of 2 strand quickmatch with some plain Al dust coating the very tip. Caution however, as it has caused catos as well.

 

I would think using a drilled booster (-0) motor for a booster on a 2 stage would allow reliable lift of heavier payloads, as well, stacking a D12 on top for sustainer would also allow for reasonably reliable booster:sustainer transition.

 

I've used a friction fit coupler to couple the motors before, and estes sustainers have no problem popping the booster off and moving out. The booster is also secured to the stabalizer (stick) by 1pc of 1/4" masking just forward of center.

 

Good luck! And your friends are correct. Estes are end burners...just not as "true" as they could be.

Edited June 23, 2011 by r1dermon

[dagabu]

You got me thinking though, what about a 3# end burner on the top of a whistle fueled rocket? No stick, just fins and a coupler, fill the nozzle with black match for ensured ignition and I may have a real high rocket. Hmmmmmm.......

 

-dag

[r1dermon]

yes indeed...in-fact, if you could figure out (reliably) the impulse of the booster/sustainer motors, you could actually work a fuse delay in there...after burnout of the booster, the mass of the rocket would continue skyward...with a program like Rocsim, you could calculate the optimal delay, and work that in. even a 1 or 2 second delay can result in hundreds, if not 1000ft of extra altitude. i've always dreamed of using a single use aerotech composite motor as a booster, and a long burn CTI "moonburner" sustainer to put up a 12 or 16" header to 2500 or even 3000ft. although at that size im almost certain you'd need an FAA waiver, and you'd have to conform to all high power rocket regulations, including field size...etc...it's cool to think about though.

 

i have made some rockets with composite motors, however i havent had a large enough field to launch them in...perhaps in september at the club shoot i'll work up the courage to let one rip...based on the combined weight, and the Ns of the rocket, im anticipating at least 1000ft of altitude, and that takes into account the 4 second delay grain built in, which coupled with the shell, should make for a total of 6-6.5 seconds of delay. granted, it's a 2" oblong shell, so at 1000ft it wont look very impressive. haha.

 

(i love tangents)

 

back to your originally scheduled thread.

[dagabu]

... im almost certain you'd need an FAA waiver, and you'd have to conform to all high power rocket regulations, including field size...etc...it's cool to think about though.

 

I am certain that there have been rockets at PGI that have gone up 6000'. There was a heavy 7 seconds of delay before hearing the salute on one of DT's rockets last summer, at 80°, I call that 6000'

 

Bring the suckers to PGI, I have cookies

 

-dag

[r1dermon]

if/when i launch them (the 2"ers) in september, i'll take video and post it for your enjoyment. composites are so much more fun than BP.

[shockie]

All Current Estes BP motors are more or less end burners in that they have a small core....back in the day, they used to have some core-burners that had a bigger formed core and then were drilled by a machine , they were first called B16 then B3 then finally B14....they are mush loved and revered among model rocketry people. Estes quit making them in the 70's. I personally wouldn't recommend drilling them out to make them more of a port burner. I have used a syringe to drop one small drop of water into the core. This single drop of water will soften the formed BP core. Using a suitable diameter piece of brass tubing (no spark) you can then simply remove a small section of the core BP. No heat, no friction, no speaks, no explosions or ignitions. Let dry overnight. If you do something like this, please wear safety glasses Remember that you only need to remove a small section say 1/8" to 1/4". Don't make the core bigger in diameter, just length it a bit. Estes model rockets are designed to work at less than 250 psi chamber pressure, with the most pressure being generated during the initial thrust spike. If the pressure gets too high, it will by design, blow the clay nozzle out , and or shoot/blow the entire BP grain/delay out the top......

 

One could, is so inclined, use an Estes 24mm C11-0, D12-0 or even an E9-P (where P means plugged, it has a clay cap on top that can be removed easily) to make it an E9-0; as the booster motors in a sky rocket......then you could have another skyrocket motor of your choosing and fuel mix on top..... If the E9-0 is used, because of its low thrust, I would use a 2-3 ft long piece of tube as a launcher.

 

 

As far as what I meant by pressing BP on top of a whistle mix, Steve LaDuke has created hybrid whistle mix/bp fuel mix rockets where he presses halfway up the coreary with whistle mix.and the top portion of the core is then pressed with BP....The thread(s) and details are over in the Passfire forum .

 

The cores on that sketch I provided are exaggerated somewhat. they should only be about 60-70% max length of the engine tube.

 

HTH

 

Terry

[dagabu]

if/when i launch them (the 2"ers) in september, i'll take video and post it for your enjoyment. composites are so much more fun than BP.

 

At x10 the price I have three 1# asphalt/Perc rockets I am launching in a few minutes, it is the original JATO comp that was used up to the early 50's (?). Is that enough composite for ya all?

 

-dag

[moondogman]

At x10 the price I have three 1# asphalt/Perc rockets I am launching in a few minutes, it is the original JATO comp that was used up to the early 50's (?). Is that enough composite for ya all?

 

-dag

 

Hey Where did ya get that idea at????? What was the formula you found?? I was hoping for a bunch of black smoke. Did you press them dry??

 

 

Steve

[dagabu]

Hey Where did ya get that idea at????? What was the formula you found?? I was hoping for a bunch of black smoke. Did you press them dry??

 

 

Steve

 

I posted the rockets on another thread and no, sadly, there was NO black smoke!! I got the idea from this bloke over on Passfire, incidentally, he has the same username as you do!

 

-dag