I'm looking forward to the swing test videos on the upper stages. Sweet base drag and inertia at speed! The sims are cool but swing rules!
Multi Stage Saturn V
- Thread starter lakeroadster
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Sure, why not.. remember though... I'm relying on spin, as well as drag, for stabilization.
Fins and FairingsTurned the fairings on the wood lathe, then cut them on the skill saw. The fins are papered 1/8" basswood. Let the gluing begin.
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Before you glue the fins on crooked...as a dedicated oddroc scumbag I will, for the last time, discuss my feelings and discussions I have had with other scum in the local cantina.
"He dosen't like your crooked fins and spin stabilization, I don't like them either. You had better watch yourself, we are wanted men, having crashed multiple oddrocs at six clubs across the State!"
Now the Master Jedi will step in and say: "This little one is not worth the effort, let me by you a drink." We say sure! Make it a double! We try and sell him silly forward canted motors and he mind tricks us into rethinking our lives and mindsimed designs. No limbs lost.
Always shoot first:
First, the lauch lug is off center. Let's say there is a lot of lovely stabilizing spin off the rod. Will it not act like when the washing machine gets off balance? Such motion is not desired at take off, especially on a complex clustered staged rocket. Rod whip? Twisty first stage ignition issues?
Second. It takes a lot of spin to stabilize a rocket, like the vertigo or monocopters I have seen successfully employ the method. Will the fins impart enough spin on the first stage lifting this monster off the pad using wimpy Estes BP motors? Will the spin last? My silly, no good mindsim says no. But they always say to trust the Machines. I can't even run a targeting computer.
Thrird. Creating a lot of tourqe on first stage cupler scares me. All those internal connections getting any twist, yikes! But I am just a scardie cat, fearing and being a prisoner to my inner RSO nerd.
OK, ignore the peanut gallery again and move on. These are not the criticisms we are looking for!
Yep, the launch lug is off center. But the hole that's drilled through solid redwood Interstage Transition, as well as the holes in the 1/8" centering rings, for the launch rod, compensates for the cardboard tube used as the internal launch lugs.
Remember, the rotation due to the fin cant isn't instantaneous. No rotation at all until some airspeed is attained. And even then all that mass has to ramp up to speed. But a body in motion tends to stay in motion. So sure , it'll slow down some once the 1st stage is gone, but I'm thinking not much.
- Usable launch rod length = 5'6". So let's look at the rockets roll rate at a height twice that = 11'-0"
- Open Rocket shows the roll rate of the rocket at a height of 11 feet = 2 rev/sec.
- Time from launch until the rocket clears the launch rod = 0.29 seconds
( 0.29 seconds ) x ( 2 rev/sec ) = 0.58 revolutions of the rocket before it clears the launch rod... and that's conservative.
My "THUNK!" rocket had canted fins and used spin to stabilize it through the coast phase up to apogee. Will this rocket have enough spin? Well, we'll see.
The internal launch lugs between the 1st and 2nd stages are coupled, that is done to ensure the stages don't rotate independently in relation to one another. Again... remember... the rotation due to the fin cant isn't instantaneous.
OK, ignore the peanut gallery again and move on. These are not the criticisms we are looking for!
I'm not ignoring you in any way. I appreciate the advice and you pointing out your areas of concern. I feel the design of this rocket addresses those concerns.
The design challenges are what makes this rocket worth the time and effort.
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Go ahead and ignore, do it your way!
Meanwhile in the dark corridors of Couroscant..."He will destroy the Death Star and face Vader too soon. Everything is going to plan, just as I have foreseen it."
At the cantina they read the responses at adjust the odds on the launch. The numbers rule! Place your bets. Just like pod racing!
"Maybe we can try a spin...that usually works!" The Jedi vice: "Anikin...!"
Whatever happens odds are it will be awesome! And that's good enough for me! Oddrocs and complex sports scale rule!
Meanwhile in the dark corridors of Couroscant..."He will destroy the Death Star and face Vader too soon. Everything is going to plan, just as I have foreseen it."
At the cantina they read the responses at adjust the odds on the launch. The numbers rule! Place your bets. Just like pod racing!
"Maybe we can try a spin...that usually works!" The Jedi vice: "Anikin...!"
Whatever happens odds are it will be awesome! And that's good enough for me! Oddrocs and complex sports scale rule!
Such a worry wart Daddy! It will stage before the small fins can react. No need to be a helicopter parent.
Fairings, Fins and a Copious Amount of Glue Fillets
A few mock-up photo's.... and then I'm spending the day making glue fillets on the fin can. I love it when a plan comes together.
A few mock-up photo's.... and then I'm spending the day making glue fillets on the fin can. I love it when a plan comes together.
This I have to see.....Looks complex and cool.
I used a 5/16" wooden dowel to ensure the internal launch lugs are in proper alignment while the glue attaching them to the internal coupler dries.
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Fired up the CAD station and designed a base stand to hold the rocket... it has (5) lathe turned components to simulate the F-1 rockets thrust chamber nozzle extensions.
Fired up the CAD station and designed a base stand to hold the rocket... it has (5) lathe turned components to simulate the F-1 rockets thrust chamber nozzle extensions.
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Why stop at the nozzles, when you can make virtual plumes too?
Now that would be illuminating!
www.instructables.com
Now that would be illuminating!
Saturn V Lamp
Saturn V Lamp: The Saturn V rocket is the most popular of all rockets, it was made famous by the historic flight of July 1969 which brought two astronauts on the lunar soil, this event took place 50 years ago ! I made this lamp imitating a flight of this amazing …
If you're building a Saturn V and looking for some good detailed data for exterior placement of decals and external pieces parts, download the instructions for Apogee Components 1/70th scale Apogee Saturn V.
There are 4 CAD model shots for each stage, with the model rotating 90 degrees for each photo.
I'm not looking to make a museum quality model rocket, like the Apogee Components version, but these instructions will allow me to make the model a bit more visually correct... as viewed on the launch pad and during flight.
The fact that Apogee Components provides links to such detailed data is the main reason I buy components from them. They are truly a class act.
Here's a sample of the Instruction Sheet CAD Model screen shots...
There are 4 CAD model shots for each stage, with the model rotating 90 degrees for each photo.
I'm not looking to make a museum quality model rocket, like the Apogee Components version, but these instructions will allow me to make the model a bit more visually correct... as viewed on the launch pad and during flight.
The fact that Apogee Components provides links to such detailed data is the main reason I buy components from them. They are truly a class act.
Here's a sample of the Instruction Sheet CAD Model screen shots...
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Your cad drawings are top notch.
Thanks. Engineering and drafting are what I did as a day job. I'm retired now... but still enjoy doing both.
___________________________________________________________________________________________________________________________________________________________________Not much progress today on the Saturn V... bought and installed a screw eye for the 3rd stage recovery streamer. I placed it on the same side of the rocket as the internal launch lug.
Why?
I did a bit of lo-tech investigation into the state of this as built rockets static balance before I installed the fins... I rolled the rocket on our counter top, and it always stopped and rolled back such that the launch lug was at the top. Evidently the holes in the centering rings and the hole drilled in the transition removed more weight than was added by the BT-3 launch lug and the copious amount of wood glue I used.
So this screw eye should help to bring the rocket closer back into balance.
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I'm pretty much done with the Titebond Q&T fillets on the ferrules and fins. I'll still need to apply some CWF, but... so far so good.
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We were at Wally World today and I picked up a package of fishing line leaders. These are 18" long and are 45 lb test rated. They have crimped ferrules, barrel swivels on one end and quick disconnect clips on the other end.
I'm thinking these might be a good option as shock chords near the ejection end of the motor, these should be very heat resistant. Not for small diameter rockets, but should work great for 3" and up.
Eagle Claw EL 1845BR6
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2nd & 3rd Stage Staging Vents
I know... it looks like a corncob pipe, right?
I've been trying to figure out the best way to install a staging vent in the 2nd and 3rd stage staging tubes. I know ideally the vent should be at the top near the motor that is being ignited, but on this rocket, with the recovery spools, that's not going to work.
I installed (2) vent tubes ( 0.18 o.d. launch lug tube, 0.140 i.d.) just above the top motor mount centering ring. I'll glue them to the staging tube, to the centering ring and to the C-300. Then when the glue is dry, I'll cut the tubes flush with the outside of the body tubes.
Think that'll work? Can't imagine that it would cause an issue?
I know... it looks like a corncob pipe, right?
I've been trying to figure out the best way to install a staging vent in the 2nd and 3rd stage staging tubes. I know ideally the vent should be at the top near the motor that is being ignited, but on this rocket, with the recovery spools, that's not going to work.
I installed (2) vent tubes ( 0.18 o.d. launch lug tube, 0.140 i.d.) just above the top motor mount centering ring. I'll glue them to the staging tube, to the centering ring and to the C-300. Then when the glue is dry, I'll cut the tubes flush with the outside of the body tubes.
Think that'll work? Can't imagine that it would cause an issue?
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Good idea to check for rotational balance since this is going to be a spinning rocket.
Preparing to finish up the 3rd and 4th stages, I am studying how the recovery streamers should be stowed and how they will deploy.
@GlenP helped me to develop a z-fold technique for the 4th stage on post #200.
I'm going to use this same type of z-fold for the 3rd stage, and make another spool so that the streamer will be protected from a direct impact of the exhaust from the 4th stage motor.
@GlenP helped me to develop a z-fold technique for the 4th stage on post #200.
I'm going to use this same type of z-fold for the 3rd stage, and make another spool so that the streamer will be protected from a direct impact of the exhaust from the 4th stage motor.
You've read this from me too many times, and your results are usually better than I I fear, but this time you asked. So I'm afraid I don't think it will work. And here's why.
Your annotation on the drawing says "Staging vents: prevents excessive pressure buildup in the staging tube." But that's not really the primary purpose of the vent. The primary purpose is to keep air/gas/particles moving all the way up to the engine to be lit. Without the vent, you've got stagnant air below the next stage engine and nothing reaches to light it. Having the vent down by the lower stage engine really doesn't accomplish that.
If you take the tube you've got above the third stage engine and move it down below then that will be in the right place to ensure lighting that engine. Then add a tube out through the side up just below the fourth stage motor as well.
Thanks for your input Joe.
I re-read the Apogee Components article about staging and what you are stating is chapter and verse.
That being said, your changes as sketched above won't work.
In this sketch, the vent tube is intersecting the motor.
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And in this one it blocks the spool from being able to eject from the rocket.
I guess I'm having problems accepting that those hot gases and flaming hot bits that break through the cap of the booster motor, with explosive, force won't still shoot up to the motor, while air vents out the (2) vent tubes.
Maybe a bench test is in order?
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Naturally, where do you think I learned it? But that doesn't make it unassailable truth, just pretty reliable.
Yeah, I never was much for interpreting mechanical drawings. That's why my sketches are generally color coded (no hatching) and amply labeled.
I won't say no to that.
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Joe is at least mostly correct (I am not sure that for long gaps ventless staging pressures COULD separate the stages before ignition, but the MAIN point is to duct the GASES close enough to the upper stage nozzle that the infrared light radiates and ignites the motor.). Stine and many others are wrong, it’s not PARTICLES it is radiant heat, proven on a NARAM presentation.
The motor tube IMO must have a hole or gap that guides the gases NEAR the motor nozzle, and for non-minimum diameter rockets there needs to be continuity with some other hole or gap through side or base of the rocket to allow decompression. But the first and last gaps do NOT need a direct duct, just some air filled space. Put another way, the holes don’t need to line up.
You don’t need the equivalent of another duct connecting the first hole with the second hole. This may give you some flexibility in design.
Ideally the first hole should be as close to nozzle as possible, but since it is PHOTONS and not particles that travel the path, you maaaay get away with an inch or two. I haven’t tried it. So bench test may be appropriate. Caveat however, I bench tested a 72” gap D to D and it worked, but did NOT work in flight, I dunno why not. So while I am all for bench testing, it isn’t perfect (then again, nothing else is either
.)
The pyro guys tell me BP just needs a lot of concentrated heat in a small area to ignite, be it spark, burning bit or IR. Like a refreshing Belgian Trappist Ale, bring on the heat! Just make it stage fast and even.
Is this the NARAM presentation you are referring to? High Speed Video Analysis of! Model Rocket Motor Staging
Where did you find data that shows that "photons" are igniting the next motor? I'm not arguing, I'd just like to see that data.
For this rocket, it would appear the best method moving forward is to just use fuses...
. I got 'em, why not use 'em.The lower holes vent pressure and should help to prevent the upper stage from premature stage separation when the booster motor "brings the fire".
.... I bench tested a 72” gap D to D and it worked, but did NOT work in flight, I dunno why not. So while I am all for bench testing, it isn’t perfect (then again, nothing else is either
What orientation did you do the test in? Vertical or Horizontal?
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Think about it this way.
You need to get the heat from the booster to your next stage, transfered via a blast of hot air from the top of your booster motor. A vent near the nozzle of the sustainer motor you are trying to ignite allows all the cooler air sitting in between the two motors to vent out of the way of the high-pressure hot air moving upward through your duct. If there is no vent, you are likely to just cause a premature separation from pressure buildup between your two stages. If your vent is down near the booster motor, the hot air is likely to just exit that lower vent without getting near the sustainer you are trying to ignite.
You need to get the heat from the booster to your next stage, transfered via a blast of hot air from the top of your booster motor. A vent near the nozzle of the sustainer motor you are trying to ignite allows all the cooler air sitting in between the two motors to vent out of the way of the high-pressure hot air moving upward through your duct. If there is no vent, you are likely to just cause a premature separation from pressure buildup between your two stages. If your vent is down near the booster motor, the hot air is likely to just exit that lower vent without getting near the sustainer you are trying to ignite.
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“Photons” is just a way to describe the electromagnetic waves that transport thermal radiation energy. Like how we get solar energy.
Probably takes a bit of both convection and radiation for staging and ignition of a sustainer. Enough of the booster burning gas needs to get near the sustainer nozzle for the heat energy to “shine” into the propellant to ignite it. That is just my personal simplified explanation.
But the fast burning fuses should also work well at getting the sustainer lighted up.
Probably takes a bit of both convection and radiation for staging and ignition of a sustainer. Enough of the booster burning gas needs to get near the sustainer nozzle for the heat energy to “shine” into the propellant to ignite it. That is just my personal simplified explanation.
But the fast burning fuses should also work well at getting the sustainer lighted up.
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That’s the one. There is a video of it somewhere.Is this the NARAM presentation you are referring to? High Speed Video Analysis of! Model Rocket Motor Staging
Where did you find data that shows that "photons" are igniting the next motor? I'm not arguing, I'd just like to see that data.
For this rocket, it would appear the best method moving forward is to just use fuses...
The lower holes vent pressure and should help to prevent the upper stage from premature stage separation when the booster motor "brings the fire".
What orientation did you do the test in? Vertical or Horizontal?
good question on “photons”, the article I think clearly demonstrates it’s not particles so I think it is a process of elimination. One of my “anti-particle” rationales has always been that the rocket nozzle is a dead end tunnel. in order for anything to enter it, something else must come out. Logically, if you Have a blast of pressurize gas and particles coming at it, it would likely COMPRESS the air already IN the nozzle, making a dam that would make it challenging for particles to penetrate. The particles would have have both velocity and sufficient mass to overcome the air dam created. For a short gap maybe, long gap I don’t think so.
regarding fuses, you make them sound great. There are lots of GREAT things that seemed frowned upon by NAR and Tripoli (@Steve Shannon , got an inside scoop on this you can share, or am I out to lunch?). since I am flying, if at all lately, on public land personally I stay within the bounds that I hope are covered by my NAR membership insurance in case of fecal turbine reaction. My suspicion is if something bad happens, even if it is completely unrelated to my transgressing the rule, it may invalidate the insurance. A classic case is self plugged motors, RSOs often nix them, and I am pretty much sure that it is more of an insurance issue than that the RSO really thinks they are unsafe, although I never asked.
the successful static test was horizontal, the failed flight test was vertical (both up and unfortunately down!). Not sure how orientation could come into play, maybe gravity was a factor?
@BEC is one of the knowledge founts this forum is blessed with, I recall something about a two stage kit that DID use fuses, so maybe it really would not only be reliable but actually officially “NAR approved”.
i was doing what seemed EXTREME long gap staging. Had to laugh when I read or heard one of TVMs blogs on Apogee that gap staging works up to 11 inches, I had been doing 36” for years without a single failure. Your gaps is pretty short, so your plan likely will work
i believe putting the closer the vent is to the nozzle the more reliable/ideal, but you challenge me and I confess that I haven’t tried vents further away. So “good enough” by definition is “good enough.”
to the chagrin of many of our Air Officer Commanders at USAFA, a common cadet saying was, “if the minimum wasn’t good enough, it wouldn’t be the minimum.” Right up there with “2.0 and go!”
Fair Skies, Light Winds, and numerous Straight Trails to you!
I always believed it was hot particles in gap staging. Infrared would be unlikely to work at the 36” that you have done, but particles could easily traverse the gap fairly quickly as long as a vent prevented stagnation. At least that’s the theory, but I’m not an expert and if there is solid evidence that something else is happening, I’m interested.
As far as using fuses, NFPA prohibits lighting a motor with a fuse that you light by hand and there’s a requirement that the launch process immediately cease if a person stops pressing the button. That’s different than simply using a fuse and it’s aimed at first stage ignition. I’ve seen launch pads blow over or be pulled over and pointing directly at myself and a young lady who backed up to the the end of the leads on a launch controller. If pressing the button starts a fuse, that rocket is still going to launch, which is not a safe situation.
As far as using a fuse to ignite an upper stage, all the concerns that accompany using a timer must be considered, but I don’t know that it’s actually prohibited for model rockets.
@BABAR and @Steve Shannon
I contacted NAR, See Post #142, using fuses is indeed permitted, since the fuse is ignited from lower stage rocket motors and not handheld.
Current plan is to use fuses to ignite 2nd, 3rd and 4th stages.
The staging test is on the to-do-list. But I'm not sure when I'll find that "round-to-it".
I contacted NAR, See Post #142, using fuses is indeed permitted, since the fuse is ignited from lower stage rocket motors and not handheld.
"Both National Fire Protection Association (NFPA) 1122, Code for Model Rocketry, and NFPA 1127, Code for High Power Rocketry, state under prohibited activities: "Selling, offering for sale, exposing for sale, purchasing, making, or using fuses, wicks, or other ignition devices intended to be activated by a handheld flame for the purpose of starting a high power (in 1127, "model" in 1122) rocket motor." Since your planned ignition is from lower stage rocket motors and not handheld, I would say that your use of quick burn fuses is permitted."
I know this thread is getting a bit long in the tooth... but I have contacted NAR twice about this specific rocket, trying my best to understand the NAR requirements, thus ensuring this rocket is NAR compliant.Current plan is to use fuses to ignite 2nd, 3rd and 4th stages.
The staging test is on the to-do-list. But I'm not sure when I'll find that "round-to-it".
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