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To really answer these questions you’ll have to build it…as Ripley would say, it’s the only way to be sure…
Multi Stage Saturn V
- Thread starter lakeroadster
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The science is way above my pay grade. All I know is I'd want to be around to watch this go off!
Does OR have a feature that lets you an altitude and speed for initial ignition? That is, "I'm starting out at xxx altitude and already going yyy speed"? If so, you could take the altitude and speed at burnout of the first stage of the full stack and enter them as the starting state of the second file, then repeat for the third and fourth. And then you'd have a chance of accurateish staging altitudes for each event and apogee.Sage advice... so it shall be written, so it shall be done.
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Why do you keep talking about CHAD? This design is not using CHAD. CHAD
The initial drawing (first post) was cheap and dirty gap staging but has been removed. Each motor was in a seperate tube. Confirmed in post #9.
Chad was killed but Slim is still somewhere in town.
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as I recall, he died from hanging.
lakeroadster
When in doubt... build hell-for-stout!
Wasn't he pregnant too? He certainly was before his time; he'd be popular in certain circles in 2022 America.
Oh cripes! That just got me thinking harder about the flash pan. If the first stage tips by any noticeable amount, the loose powder would fall to the low side of the pan and really wouldn't get the job done.
Yes, that. Fuse might really be the better idea. But then, I guess you've already decided to go that way; I'm late to the party.
On the other hand, I read a research report some years ago showing that there is a considerable performance loss when using fuse to light a BP motor because it takes longer to come up to pressure, and by that time some of the powder is gone. A dab of really hot pyrogen on the end of the fuse might be a good idea.
The sound of a record scratch leading to a sudden halt.
Calculations like this, especially those with safety implications, must be conducted with worst case assumptions. It's 0.4 sec/ft.
I'm at work now (and shouldn't be on the forum, but I am) and I just had a bitch and moan session with another engineer about our company accepting simulations in lieu of qualification testing, and the trouble we have because of it while commissioning new (train) cars. The proof of the pudding is in the eating. Take a little taste of the pudding before serving it. It's the only way to be sure.
lakeroadster
When in doubt... build hell-for-stout!
Spit-balling again here:
- Envision a custom-made flash pan with cups. A cup that holds the bp for each motor. The cups will hold the BP in place during the 1st stage flight even when the rocket is rolling about the longitudinal axis.
- The tray with the cups can be made by creating a mold from a piece of wood. Drill holes in the wood with a Forstner bit where the motors would be. Use a wood chisel to make interconnecting passages between the cups. Then use this mold to make a tin foil pan.
I recently read of a very clever cluster lighter improvement on the flash pan. I think it was in a recent Sport Rocketry. Call it a flash can. There's a closed can with small diameter tubes sticking up from the top directly at the nozzles of the engines. A BP charge is inside the can, with an igniter (or fuse in this case) entering from the side. Once the powder lights, there's nowhere for the hot material to go except right where it needs to.
As for the powder moving around, in the time since I wrote that last post a solution has come to me. Flash paper. Since flash paper is partially nitrated, a blend of unaltered paper and nitrocellulose, it should get sticky when moistened with acetone, not that I've ever tried it. So moisten a disc that matches the bottom of the flash can then sprinkle BP onto it. The fuse and disc go into the can, the lid goes onto the can, the can goes into the top of the first stage, and Bob's your uncle.
Since only the center motor will be a -0, you could do normal parachute deployment later by blowing the can out instead of a nose cone.
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After thought: the tubes have to be aligned with the engines, which might be tricky when putting the stages together. So add a dowel, taller than the tubes, which goes through a hole in the second stage's aft centering ring.
As for the powder moving around, in the time since I wrote that last post a solution has come to me. Flash paper. Since flash paper is partially nitrated, a blend of unaltered paper and nitrocellulose, it should get sticky when moistened with acetone, not that I've ever tried it. So moisten a disc that matches the bottom of the flash can then sprinkle BP onto it. The fuse and disc go into the can, the lid goes onto the can, the can goes into the top of the first stage, and Bob's your uncle.
Since only the center motor will be a -0, you could do normal parachute deployment later by blowing the can out instead of a nose cone.
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After thought: the tubes have to be aligned with the engines, which might be tricky when putting the stages together. So add a dowel, taller than the tubes, which goes through a hole in the second stage's aft centering ring.
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My ignorance is again showing. I AM familiar with flash pans used to ignite first stage boosters off the pad. I haven’t heard of using flash pans IN FLIGHT to light sustainers or mid stage motors. Of course, there’s lots of memos I miss.
On the off chance there is fecal turbine interaction and the rocket goes landshark off the pad, while gap or nongap staging would ALSO be bad (one downs side of nonelectronic staging, once you hit the launch button there are no safety inhibitors for abnormal flights) a flash pan seems likely to add insult to injury. Igniting boosters on the ground (not on pad) is bad enough, igniting a flash pan on the ground also sounds ominous.
Plain old BP to BP gap or nongap staging seems more reliable . If you have different motor orientation (either different numbers of motors or different centering, so can’t do nongap or traditional one to one gap) you CAN duct booster motor gas blow through (technically it isn’t ejection) slightly angled to off set boosters. This was done with the Estes MIRV kit one booster to three sustainers (great concept and staging worked, unfortunately severely underpowered with 18 mm motorC6-0), and I’ve done two separate rockets scratch with one booster ducted to three sustainers and worked well (only did 1 or 2 flights each, but 100% success rate.). Mine were 24mm D12-0 to three A8-5s (or maybe A8-3s, it’s been a while.)
It’s challenging to make scratch ducts from paper body tubes. I have no experience with 3D printing but suspect with heat resistant plastic (MIRV had a plastic manifold fin can, that was the problem, no easy way to upsize from 18 mm to 24) or liberal internal JB weld would make for both reliable stage ignition as well as good solid coupling.
If Estes finally releases the C5-0 many of us are hoping for, they should re-release the MIRV. They SHOULD redesign the sustainers, they are actually unstable although doesn’t matter much because the are so high at staging there isn’t anything for them to hit.
On the off chance there is fecal turbine interaction and the rocket goes landshark off the pad, while gap or nongap staging would ALSO be bad (one downs side of nonelectronic staging, once you hit the launch button there are no safety inhibitors for abnormal flights) a flash pan seems likely to add insult to injury. Igniting boosters on the ground (not on pad) is bad enough, igniting a flash pan on the ground also sounds ominous.
Plain old BP to BP gap or nongap staging seems more reliable . If you have different motor orientation (either different numbers of motors or different centering, so can’t do nongap or traditional one to one gap) you CAN duct booster motor gas blow through (technically it isn’t ejection) slightly angled to off set boosters. This was done with the Estes MIRV kit one booster to three sustainers (great concept and staging worked, unfortunately severely underpowered with 18 mm motorC6-0), and I’ve done two separate rockets scratch with one booster ducted to three sustainers and worked well (only did 1 or 2 flights each, but 100% success rate.). Mine were 24mm D12-0 to three A8-5s (or maybe A8-3s, it’s been a while.)
It’s challenging to make scratch ducts from paper body tubes. I have no experience with 3D printing but suspect with heat resistant plastic (MIRV had a plastic manifold fin can, that was the problem, no easy way to upsize from 18 mm to 24) or liberal internal JB weld would make for both reliable stage ignition as well as good solid coupling.
If Estes finally releases the C5-0 many of us are hoping for, they should re-release the MIRV. They SHOULD redesign the sustainers, they are actually unstable although doesn’t matter much because the are so high at staging there isn’t anything for them to hit.
I haven't heard of it either, and the fact that we're all brain storming ways to work around the probable problems would seem to be evidence (not proof) that it hasn't been done before. And perhaps evidence that it shouldn't be.
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As Mom used to say, “ Just because you can do it doesn’t mean you should do it.”
lakeroadster
When in doubt... build hell-for-stout!
lakeroadster
When in doubt... build hell-for-stout!
Moving forward I plan to use the fast-burning fuse to ignite the 2nd stage motors. Thanks to @heada, @GlenP and @Rocketjunkie for their input on the use of the fuses.
lakeroadster
When in doubt... build hell-for-stout!
A couple more questions, initiated via @GlenP's comments (see below)....
- Did you run 5 fuses down to the C6-0 and bundle them together?
- Are there a lot of sparks being sluffed off while the fuse is burning?
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heada
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Yes, 5 individual sections of fuse. At the booster end they were bundled together so that the booster motor ignited them all. Tied together with cotton kite string.
The fuse gives off almost no sparks/flames when burning inside the paper shell but it burns so fast you almost can't tell. To protect the fuse from one of the non-booster motors and to protect everything else from the fuse, I wrapped them in aluminum tape.
Starting from the C6-0, 5 sections of fuse with 1/4" of the insides exposed. All tied together into a bundle with thin cotton kite string and then a wrap of aluminum tape. The end of the bundle is not secured to the booster motor so that each stage can be prepared separately but the bundle fits down into the booster MMT freely. Up about 2 inches, the bundle split apart inti their individual fuses. Again wrapped in aluminim tape and leading up to the 5 motors in the next stage. Fuse ends were expised 1/4" and inserted into the nozzle and secured with the soft plastic nozzle plug and then taped over with aluminum tape.
When I did a test burn of the fuse in my backyard, I waved my mapp gas torch over the end and in what I can only explain as nearly magic, the 1ft section disappeared before I could prepare myself. If you've ever used green fuse on fireworks, this is absolutely nothing like that at all. It is much more like a pile of 4Fg BP that you toss a match into. Its there and then not. No sparks or flame, just fuse and then paper bits. Even assuming the 0.4 sec per foot, the 5inch sections burn in 0.17sec If its the fast version the 5inches burn in 0.04sec. 40msec!
The fuse gives off almost no sparks/flames when burning inside the paper shell but it burns so fast you almost can't tell. To protect the fuse from one of the non-booster motors and to protect everything else from the fuse, I wrapped them in aluminum tape.
Starting from the C6-0, 5 sections of fuse with 1/4" of the insides exposed. All tied together into a bundle with thin cotton kite string and then a wrap of aluminum tape. The end of the bundle is not secured to the booster motor so that each stage can be prepared separately but the bundle fits down into the booster MMT freely. Up about 2 inches, the bundle split apart inti their individual fuses. Again wrapped in aluminim tape and leading up to the 5 motors in the next stage. Fuse ends were expised 1/4" and inserted into the nozzle and secured with the soft plastic nozzle plug and then taped over with aluminum tape.
When I did a test burn of the fuse in my backyard, I waved my mapp gas torch over the end and in what I can only explain as nearly magic, the 1ft section disappeared before I could prepare myself. If you've ever used green fuse on fireworks, this is absolutely nothing like that at all. It is much more like a pile of 4Fg BP that you toss a match into. Its there and then not. No sparks or flame, just fuse and then paper bits. Even assuming the 0.4 sec per foot, the 5inch sections burn in 0.17sec If its the fast version the 5inches burn in 0.04sec. 40msec!
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lakeroadster
When in doubt... build hell-for-stout!
Thanks for explaining this in such a detailed manner Aaron.
GuyNoir
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The original term for these is "spider".
lakeroadster
When in doubt... build hell-for-stout!
I decided to update the design to allow for 24mm motors in the 1st stage. It's a subtle change from 2.64 O.D. to 3.00 O.D. but gives the flyer a lot of options in different motor configurations. The scale is 1/132.
1st Stage = (5) 24mm
2nd Stage = (5) 18mm
3rd Stage = (1) 18mm
4th Stage = (1) Estes mini A
Time to fire up the CAD station, make some drawings and order some body tubes. This is going to be a fun rocket.
1st Stage = (5) 24mm
2nd Stage = (5) 18mm
3rd Stage = (1) 18mm
4th Stage = (1) Estes mini A
Time to fire up the CAD station, make some drawings and order some body tubes. This is going to be a fun rocket.
Thanks.
lakeroadster
When in doubt... build hell-for-stout!
Worked on the CAD drawings for the 1st stage....
Comparing thrust curves for a C11 and D12: If I use a C11 in the first stage to ignite the quick fuses for the 2nd stage... that means the 2nd stage motors should fire off just before the D12 1st stage motors burnout.
Comparing thrust curves for a C11 and D12: If I use a C11 in the first stage to ignite the quick fuses for the 2nd stage... that means the 2nd stage motors should fire off just before the D12 1st stage motors burnout.
A little late to the fuse/flashpan discussion, but what if you did both? Have the fuse be functional, but with a not practical flashpan for the visual appeal 
. Men are that they might have joy.
. Men are that they might have joy.
boatgeek
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Not sure I agree with your math there. The D12 burns for 0.9s after the C11 burnout. at 0.1 to 0.4 s/foot, you'd need fuses 2 to 9 feet long. That seems really long. Any reason not to use a D12-0 in the center? If you end up with too much propellant for Class 1, you could switch down to C11's outboard (or 2 of the 4 outboards).
heada
Well-Known Member
Personally I'd accept that it needs to be a class 2 rocket with a waiver due to total propellant mass. Then use the fastest burning set in the first stage to get it going and stable. Then less fast in the following stages. The D12 has a good initial spike but are there better BP motors for the first stage? If B14s were available I'd suggest that but what about C5?
lakeroadster
When in doubt... build hell-for-stout!
Thanks for the comments fella's.
I was merely thinking the 2nd stage motors firing early would be a good thing, better than firing late. There always seems to be a lag time between the time the launch button is pushed and ignition of the BP motor, even with e-matches. I'm assuming that will also be the case when using the fuses? Is that a bad assumption? Is there some reason the 2nd stage firing before 1st stage burnout would be a problem?
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heada
Well-Known Member
What I've seen as a delay on starting BP motors is the time it takes for an igniter to heat up and cause the pyrogen to ignite. Once the pyrogen ignites, the BP in the motor ignites. Then maybe some msec of time for the BP to burn and create thrust.
From the time flame hits the exposed end of the fuse to the time flame is passed to the next stage is less than 200msec assuming the slowest speed for the fuse and less than 45msec assuming the fastest. You don't have the time for the nichrome wire to heat and then ignite the pyrogen.
If using the fuse to pass fire from the booster motor to the next stage, I would include a 0.2sec ignition delay.
I would highly recommend testing it out on the ground and recording it. You'll be amazed how fast it'll stage between motors.
From the time flame hits the exposed end of the fuse to the time flame is passed to the next stage is less than 200msec assuming the slowest speed for the fuse and less than 45msec assuming the fastest. You don't have the time for the nichrome wire to heat and then ignite the pyrogen.
If using the fuse to pass fire from the booster motor to the next stage, I would include a 0.2sec ignition delay.
I would highly recommend testing it out on the ground and recording it. You'll be amazed how fast it'll stage between motors.
I would expect a bit more delay, because there's always a bit of delay even with direct staging. Whoosh, pause, whoosh. I'ts hard to estimate, bit it's not trivial. Maybe a quarter second? Maybe less?
Precision staged & clustered rocket science, that is a problem with mass produced, lowest cost possible, BP motors. So many variables, from quality of components, variations in secret mix formulas to manufacturing and handling. Must get the timing exactly right, but using ancient black powder and fuse technology. How did the ancients do it??? The Dark Arts and necromancy! Trust in thrust! Seek the wisdom of experienced pyros who know how to time explosions with old world mysticism.
lakeroadster
When in doubt... build hell-for-stout!
More work on the 1st and 2nd stage CAD models, including the spider quick fuse.
