GregP
Major
That's probably why no solid fuel rocket has ever been designed that way. I'd say more, but it appears to be pointless.
The Reno Racing Engines
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razor1uk
Staff Sergeant
Pressure in the bowels, gives a warm feeling, and when released via a sphicter, warmth, sound smell or energy are released, sometimes with force; just like a rocket, but luckely with much less propulsive forces - if it wasn't for you guts and internal plumbing making the anus the an easier exit or nozzel/exhaust - due to them being much morerestricting gas flowing that way, we'd be farting from our mouths as well as just belching talking etc.
Apologies for such crudely descriptive anal-ogy, but it maybe easier to understand in laymans terms.
A theory is an idea that has more knowledge within it than the idea it started from... normally to prove a point of a hypothesis, or for some sciences and mathematics, to justify their way is correct enough to fit with a predetermined answer or question.
Apologies for such crudely descriptive anal-ogy, but it maybe easier to understand in laymans terms.
A theory is an idea that has more knowledge within it than the idea it started from... normally to prove a point of a hypothesis, or for some sciences and mathematics, to justify their way is correct enough to fit with a predetermined answer or question.
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- Thread starter
- #83
PWR4360-59B
Senior Airman
- 379
- May 27, 2008
Use a coiled up air hose, and the nozzle is the rocket what is the front and rear of the pressure chamber slash combustion chamber? Park it in a rocket in space with the air exiting out of the front of the air tank. If the air tank was stationary with a milliion mile hose sticking out the velocity out of the nozzle would still do the propelling of said rocket. Do the same with said combustion chamber and pipe said combustion presure through a million mile hose, yeah I know losses. But the theory is correct.
Cut the end off a high pressure air or water hose, that jet shooting out does not care where the combustion source is, of if you wish the high pressure source. There is no force that is just on the front of the combustion chamber, its everywhere in the chamber, ie airtank.
Cut the end off a high pressure air or water hose, that jet shooting out does not care where the combustion source is, of if you wish the high pressure source. There is no force that is just on the front of the combustion chamber, its everywhere in the chamber, ie airtank.
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GregP
Major
A coiled up air hose has more in common with Razor1uk's reply than with a combustion chamber, even if he might be a bit of a twit to post that. Pneumatics has very little in common with explosive ignition of a stoichiometric air-fuel ratio in a cylinder. But, if Razor1uk is fed up, so are others. I say you and I agree to disagree ... as I have suggested before and will implement now. You will notice by my lack of replies going forward ... but you can look up the calculation of pressure on a hose nozzle and easily determine for yourself if it has any relation to calcualtion of rocket thrust. The formulas are completely unrelated.
When you invent a successful engine, I may believe you. Until then, I'll stay with the Allison V-1710's I build and the engines I fly, and they work as I said they do, just like we were taught in school. So, let's just say you have a unique viewpoint not shared by most aviation mechanics or engineers. What the heck, we may be all wrong ... In the end, if you think wrong but fly right, it won't make any difference to anyone.
I am expending beer and time thinking about it, though, so, beer and good thoughts to you meanwhile. Cheers and good luck.
When you invent a successful engine, I may believe you. Until then, I'll stay with the Allison V-1710's I build and the engines I fly, and they work as I said they do, just like we were taught in school. So, let's just say you have a unique viewpoint not shared by most aviation mechanics or engineers. What the heck, we may be all wrong ... In the end, if you think wrong but fly right, it won't make any difference to anyone.
I am expending beer and time thinking about it, though, so, beer and good thoughts to you meanwhile. Cheers and good luck.
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- Thread starter
- #85
PWR4360-59B
Senior Airman
- 379
- May 27, 2008
Pneumatics does have something in common with how those explosive gases work in an engine though. There are many piston engines that run on compressed air, a rocket will work on it. As a kid I had a toy rocket that you pumped air into and it flew.
Oh and a good example of "ducting" the medium into the rocket nozzle below.
Air powered engine
View: https://www.youtube.com/watch?v=voU3aRzOY7o
Water hose rocket engine
View: https://www.youtube.com/watch?v=zP53h5yrE48
Another water hose rocket
View: https://www.youtube.com/watch?v=l_i34PXKUyc
Oh and a good example of "ducting" the medium into the rocket nozzle below.
Air powered engine
View: https://www.youtube.com/watch?v=voU3aRzOY7o
Water hose rocket engine
View: https://www.youtube.com/watch?v=zP53h5yrE48
Another water hose rocket
View: https://www.youtube.com/watch?v=l_i34PXKUyc
GregP
Major
Damn Enguy, you keep coming up with things I can't ignore. A water "rocket" isn't a rocket at all. A rocket is an engine and a "water rocket" is not. It has no combustion chamber. Pneumatics have nothing whatsoever to do with a rocket, which is powered by combustion, not compressed air. The only similarity is pressure. In the case of a "water rocket," the pressure falls off rapidly and has nothing in common with the performance of a solid-fuel rocket except the abilty to gain altitude ... a very small amount in the case of the water rocket; air p[rssure creates water pressure ina fixed-volume einvironment. We all recall: pv - nrt ; ... or we don't. It's the perfect gas law from high school Physics.
If you had simply said "peace," we could have disengaged, but your theories are both unsupported and unsuportable. You cite things that happen and suppose a theory instead of looking at the phenomena involved in the existing devices and recognize the facts. Please, I am asking with sincerity, leave me alone and stop replying to me with inciting theories.
Let's just STOP, OK? Please address your replies to anybody else other than me. Maybe Flyboyj? Or any other A&P with experience.
I don't want to get ugly and your ideas are leading my replies there. Make any staements you want, but please don't answer any of my posts and expect a reply without formulas and numbers on your part first. We are WOLRLD's apart in science perception. Maybe we can agree that the force gets transmitted through the engne mount. Please don't answer if it just to give another theory. I'll assume it is not with agreement. If you DO answer, please back it up with example calculations or forego the exercise. Let's talk numbers if we talk, not some short-worded theory. How about real-world examples with the math behind it? I'm very tired of being the only technologist answering and getting only words back with no corroborative numerical backup.
So, if you don't have numbers and reasons for calculating the way you do, please leave replies to my posts alone. I hope you make your technical case as I enjoy the math.
Go in peace and have inventive thoughts.
If you had simply said "peace," we could have disengaged, but your theories are both unsupported and unsuportable. You cite things that happen and suppose a theory instead of looking at the phenomena involved in the existing devices and recognize the facts. Please, I am asking with sincerity, leave me alone and stop replying to me with inciting theories.
Let's just STOP, OK? Please address your replies to anybody else other than me. Maybe Flyboyj? Or any other A&P with experience.
I don't want to get ugly and your ideas are leading my replies there. Make any staements you want, but please don't answer any of my posts and expect a reply without formulas and numbers on your part first. We are WOLRLD's apart in science perception. Maybe we can agree that the force gets transmitted through the engne mount. Please don't answer if it just to give another theory. I'll assume it is not with agreement. If you DO answer, please back it up with example calculations or forego the exercise. Let's talk numbers if we talk, not some short-worded theory. How about real-world examples with the math behind it? I'm very tired of being the only technologist answering and getting only words back with no corroborative numerical backup.
So, if you don't have numbers and reasons for calculating the way you do, please leave replies to my posts alone. I hope you make your technical case as I enjoy the math.
Go in peace and have inventive thoughts.
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- Thread starter
- #87
PWR4360-59B
Senior Airman
- 379
- May 27, 2008
The whole of this argument is what you said about the pressure at the FRONT of the combustion chamber. And yes the water is doing just like a rocket engine. Look and see, its no different than say the rocket belt deal where hydrogen peroxide is run through a silver catalist and steam is produced. Combustion or what ever creates pressure in a vessel like the water or the air tank no difference what so ever as far as the pressure and how it is used to create the thrust except maybe the psi involved, you don't need combustion to make a rocket engine nor do you need combustion to make a reciprocating engine run proven that too.
View: https://www.youtube.com/watch?v=-2Db2W0hjUg
I have proven you wrong many times now that pressure at the front of the combusiton chamber is not what makes the rocket thrust. As aways you keep reading things into what I say without reading what I say. You kept referring and with coments about my engine design etc insinuating I was some kind of idiot. The facts have shown the opposite.
You mention direct this all to someone else, I wish someone else with some sense would jump in and explain it to you.
Math?
http://www.grc.nasa.gov/WWW/k-12/airplane/rktthsum.html
Again argue with nasa, THRUST DEPENDS ON MASS FLOW RATE THROUGH THE ENGINE. THE EXIT VELOCITY AT EXHAUST. PRESSURE AT THE NOZZLE. The nozzle is the key. Nothing about PRESSURE AT THE FRONT OF THE COMBUSTION CHAMBER.
whats our next fun topic of discussion?
View: https://www.youtube.com/watch?v=-2Db2W0hjUg
I have proven you wrong many times now that pressure at the front of the combusiton chamber is not what makes the rocket thrust. As aways you keep reading things into what I say without reading what I say. You kept referring and with coments about my engine design etc insinuating I was some kind of idiot. The facts have shown the opposite.
You mention direct this all to someone else, I wish someone else with some sense would jump in and explain it to you.
Math?
http://www.grc.nasa.gov/WWW/k-12/airplane/rktthsum.html
Again argue with nasa, THRUST DEPENDS ON MASS FLOW RATE THROUGH THE ENGINE. THE EXIT VELOCITY AT EXHAUST. PRESSURE AT THE NOZZLE. The nozzle is the key. Nothing about PRESSURE AT THE FRONT OF THE COMBUSTION CHAMBER.
whats our next fun topic of discussion?
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GregP
Major
OK, you get an "F" in Physics ...
- Thread starter
- #89
PWR4360-59B
Senior Airman
- 379
- May 27, 2008
That gives you an X.
razor1uk
Staff Sergeant
Of course you don't hear about the pressure at the front end of the combustion chamber in a rocket motor, because the nozzle/exhaust area of the nozzle is normally so much less restrictive to flow, that the escaping pressure and mass of the rockets propellants take the easiest way out.
For every equal and opposite reaction, because the exhaust flows out and it is greater than the resistance to the object moving, it moves it in the opposite direction.
It's taken for granted that there is some forward force/pressure in the chamber - it helps guide the major portion of the rocket gasses to the exit or the chamber, without factoring in, how the fuel systems orientation of its nozzles reqired/designed are aiming injected/sparayed of fuel(s) into the chamber.
A 'water rocket' in my view, the storage tank(s) are also the combustion chamber and the bottle neck, is the nozzle; as to it being a rocket, it doesn't involve heat for added force in its propulsion like an typical 'rocket' - although pumping it up does create heat in your muscles and in the bicycle pump......
For every equal and opposite reaction, because the exhaust flows out and it is greater than the resistance to the object moving, it moves it in the opposite direction.
It's taken for granted that there is some forward force/pressure in the chamber - it helps guide the major portion of the rocket gasses to the exit or the chamber, without factoring in, how the fuel systems orientation of its nozzles reqired/designed are aiming injected/sparayed of fuel(s) into the chamber.
A 'water rocket' in my view, the storage tank(s) are also the combustion chamber and the bottle neck, is the nozzle; as to it being a rocket, it doesn't involve heat for added force in its propulsion like an typical 'rocket' - although pumping it up does create heat in your muscles and in the bicycle pump......
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GregP
Major
A water rocket works "kind of" like a rocket at first, but it has a fixed amount of pressure water, and dissipates rapidly, without renewal of pressure.
In a solid fuel rocket, the fuel (actually fuel, oxidizer, and catalyst mixed) has holes drilled through it, and the surface area stays relatively constant as it burns, and it produces a relatively constant thrust force over the fuel burn duration. Not exactly constant, but relatively. So, the thrust stays relatively constant. Ideally, it would be a square funtion with a constant amplitude. in reality, it builds over time, reaches a peak, and decays slightly until the fuel begins to burn out, and then decays to zero over time. So the ideal square pulse has a slope upward at the front (steep), and slope downward (slowly) over the thrust duration, and slope (steep) downward when the fuel starts to lose surface area rapidly as it burns out.
The impulse momentum produced, which imparts kinetic energy to the rocket, is the integration of the force produced over time [usually gives pound-seconds [(slug-ft) / sec] or Newton-seconds (kg-m)/s]. Most load cells can give you a real-time readout of the force, in pounds or Newtons, and any decent oscilloscope (we used Nicolet scopes with digital math capability) can perform a digital integration of the force waveshape to get Newton-seconds or pound-seconds (which can be converted into Newton-seconds). Of course, the circuits have rise tme constraints, but the accuracy is very good, especially with piezoelettric presure transducers (we usually used Kistler piezo units and Honeywell-Sensotech load cells).
The thrusters we designed and built worked OK for the Space Shuttle. NASA agreed with my analyses. So did Martin Space Systems, and the Space Shuttle did some things wrong, but the thrust supplied by our thrusters in the nose caps of the SRB's and other thruster locations worked as desgned for a LONG TIME.
Sorry Engguy, but my stuff has flown in space for the USA and functioned as designed, perfectly. I didn't get an "x" in Physics; I got an "A," at least as far as my company was concerned. When you get something into space and it works for more than 30 years, come back and tell us about it. I was a test engineer and test manager, and was for more than 30 years in electronics and aerospace. I taught electronics and Physics, and still do on occasion. Mostly these days (actually the last 3 months or so), I build Allison V-1710 engines with a friend who is the best Allison guy in the world. Our engines are flying in P-38's, P-39's. P-40's. P-63's, Yak-3's, and are running in tractors and boats around the world. We recently finished the engine for Art Arfons' old "Green Monster" dragster (restored and currently owned by John Rolley of Tucson). We supplied the Allisons for Rod Lewis P-38F "Glacier Girl." Our Allisons are flying in the USA, England, Australia, New Zealand, and France as you read this.
Force MUST be applied at some point to be effective, and my contention, that worked on the Space Shuttle and various military missiles and rockets (including the Navy Standard Missile / Aegis) , is that the force MUST be applied through the engine mount, and both the pressure differential at the nozzle throat-exit and mass flow rate / velocity together supply the propulsive force of any reaction engine, acting through the engine case itself. If that is not the real case, then why is the engine bolted securely into the engine mount?
This is frustrating from a logical standpoint, but OK. Perhaps it IS a good time to retire and work on old WWII Allison engines for fun. It actually IS fun, and I don't have to deal with difficult students anymore. Let's just say the Engguy and I disagree, and probably will until his designs come to fruition and start working in the real world. At that time, we'll probably agree and have a pleasant beer together.
I'm waiting for his 12,000 HP aero engine. I have no doubt he can design and build a 12,000 HP engine ... but I don't think it will fly (actually get an airframe airborne).
In a solid fuel rocket, the fuel (actually fuel, oxidizer, and catalyst mixed) has holes drilled through it, and the surface area stays relatively constant as it burns, and it produces a relatively constant thrust force over the fuel burn duration. Not exactly constant, but relatively. So, the thrust stays relatively constant. Ideally, it would be a square funtion with a constant amplitude. in reality, it builds over time, reaches a peak, and decays slightly until the fuel begins to burn out, and then decays to zero over time. So the ideal square pulse has a slope upward at the front (steep), and slope downward (slowly) over the thrust duration, and slope (steep) downward when the fuel starts to lose surface area rapidly as it burns out.
The impulse momentum produced, which imparts kinetic energy to the rocket, is the integration of the force produced over time [usually gives pound-seconds [(slug-ft) / sec] or Newton-seconds (kg-m)/s]. Most load cells can give you a real-time readout of the force, in pounds or Newtons, and any decent oscilloscope (we used Nicolet scopes with digital math capability) can perform a digital integration of the force waveshape to get Newton-seconds or pound-seconds (which can be converted into Newton-seconds). Of course, the circuits have rise tme constraints, but the accuracy is very good, especially with piezoelettric presure transducers (we usually used Kistler piezo units and Honeywell-Sensotech load cells).
The thrusters we designed and built worked OK for the Space Shuttle. NASA agreed with my analyses. So did Martin Space Systems, and the Space Shuttle did some things wrong, but the thrust supplied by our thrusters in the nose caps of the SRB's and other thruster locations worked as desgned for a LONG TIME.
Sorry Engguy, but my stuff has flown in space for the USA and functioned as designed, perfectly. I didn't get an "x" in Physics; I got an "A," at least as far as my company was concerned. When you get something into space and it works for more than 30 years, come back and tell us about it. I was a test engineer and test manager, and was for more than 30 years in electronics and aerospace. I taught electronics and Physics, and still do on occasion. Mostly these days (actually the last 3 months or so), I build Allison V-1710 engines with a friend who is the best Allison guy in the world. Our engines are flying in P-38's, P-39's. P-40's. P-63's, Yak-3's, and are running in tractors and boats around the world. We recently finished the engine for Art Arfons' old "Green Monster" dragster (restored and currently owned by John Rolley of Tucson). We supplied the Allisons for Rod Lewis P-38F "Glacier Girl." Our Allisons are flying in the USA, England, Australia, New Zealand, and France as you read this.
Force MUST be applied at some point to be effective, and my contention, that worked on the Space Shuttle and various military missiles and rockets (including the Navy Standard Missile / Aegis) , is that the force MUST be applied through the engine mount, and both the pressure differential at the nozzle throat-exit and mass flow rate / velocity together supply the propulsive force of any reaction engine, acting through the engine case itself. If that is not the real case, then why is the engine bolted securely into the engine mount?
This is frustrating from a logical standpoint, but OK. Perhaps it IS a good time to retire and work on old WWII Allison engines for fun. It actually IS fun, and I don't have to deal with difficult students anymore. Let's just say the Engguy and I disagree, and probably will until his designs come to fruition and start working in the real world. At that time, we'll probably agree and have a pleasant beer together.
I'm waiting for his 12,000 HP aero engine. I have no doubt he can design and build a 12,000 HP engine ... but I don't think it will fly (actually get an airframe airborne).
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- Thread starter
- #92
PWR4360-59B
Senior Airman
- 379
- May 27, 2008
Really is frustrating from a logical standpoint, especially when that gas could be spewing from the front of the chamber and go through a 180 degree bend to the nozzle. Then the chamber pressure is at the rear, yet the thrust from the rear escaping gases would push the ship forward.
Why is this simple logic so difficult for a top engineer? I don't want to crap on a most likely very nice and likely intelligent gent. But yeah me frustrated too.
I have only worked on older ac engines too for fun, except when as a youngster, got paid the big bucks turnin bolts on R1830's and 2800's as helper, $1.60 per hour.
Why is this simple logic so difficult for a top engineer? I don't want to crap on a most likely very nice and likely intelligent gent. But yeah me frustrated too.
I have only worked on older ac engines too for fun, except when as a youngster, got paid the big bucks turnin bolts on R1830's and 2800's as helper, $1.60 per hour.
GregP
Major
$1.60 per hour? I hope that was at least minimum wage at the time! And I hope you get considerably more today. Wherever you live, if you happen to get to Southern California, please stop in at the Planes of Fame at Chino airport or at Joe Yancey's shop ay Rialto airport and say "Hello."
I'm pretty sure we'd have a pleasant discussion and a great afernoon of aviation-related stuff.
While we seem to clash in here, I bet we'd get along and agree on most subjects. I'd be very glad if this can get into a better mode than we were in ...
We started out with Reno Racing Engines. At the Planes of Fame, we currently have the remains of the R-3350 on Race 232 (formerly September Fury). The engine still LOOKS great, but is basically scrap metal. We have the current National Champ (Steve Hinton Jr.), and have Strega there on a regular basis. Argonaut and Dreadnought stop in on occasion.
You might enjoy the visit. I'm there (at POF) on Saturdays, am at Joe Yancey's most other days, and would like to meet you. If you come by, we'll drag out a fresh Allison and run it (we don't need much of an excuse to run one ...).
I'm pretty sure we'd have a pleasant discussion and a great afernoon of aviation-related stuff.
While we seem to clash in here, I bet we'd get along and agree on most subjects. I'd be very glad if this can get into a better mode than we were in ...
We started out with Reno Racing Engines. At the Planes of Fame, we currently have the remains of the R-3350 on Race 232 (formerly September Fury). The engine still LOOKS great, but is basically scrap metal. We have the current National Champ (Steve Hinton Jr.), and have Strega there on a regular basis. Argonaut and Dreadnought stop in on occasion.
You might enjoy the visit. I'm there (at POF) on Saturdays, am at Joe Yancey's most other days, and would like to meet you. If you come by, we'll drag out a fresh Allison and run it (we don't need much of an excuse to run one ...).
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- Thread starter
- #94
PWR4360-59B
Senior Airman
- 379
- May 27, 2008
Wow that would be very cool. Its been many many years since I've been in Ca. I may take you up on that someday. And yes min wage at the time.
