Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Ilinca Sergiu on 22/06/2014 10:42:39
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What do you think- my engine on the Oberth effect will work or not?
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this is the main part explaining the Oberth effect: (citation)-
"Take 1/2 of m (v + vb)v2, and you get 1/2 mv2 as well as 1/2 mvb2, the kinetic energy you'd expect from adding these two speeds. On top of that, you also get m(v * vb). The pink rectangle above is Oberth gravy.
For example a kilogram going 10 meters/second has kinetic energy of 50 joules; a kilogram going 2 meters/second has kinetic energy of 2 joules. But a kilogram moving (10 + 2) meters/second doesn't have a kinetic energy of 52 joules, rather (50 + 2 + (10 * 2)) joules. Starting with a 10 meter/second speed and speeding up another 2 meters a second gives you a 20 joule Oberth benefit.
So accelerating a mass already moving fast gives you more kinetic energy for your buck."
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I am correctly or not-in this case here?
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I think in the case of accelerating, the energy of the jet stream will be:
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I propose to consider a model, in which supposedly thrust nozzle behaves like a mass.( resists the movement as some mass). In this case- in my opinion F=F*v=10000000kg, in Oberth opinion m=(v*vb)=10000000kg. What is it : a simple coincidence? I and Oberth are wrong? Or are both right,and we see the same process-which is outside incorrectly seen as (v+v).
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Wikipedia about the Oberth effect (why the motion of a rocket increases the kinetic energy of the propellant ):
- e=av
- E=Fv
- E=Fs
I try to show that:
-If acceleration increases the weight of the propellant in a nozzle : ( ma=F ) , F=mav,
-If to consider (F) of thrust identical to (m) mass : (F=m) , F=Fv,
-If not consider (F) of thrust identical to (m) mass : F=m(v*vb) ,that is identical to F=Fv,
-if considered covered by a nozzle distance (s) instead of speed (v) : F=Fs,
See no differences except the fact that I have the engine moves relative to the ship, Oberth relative to the selected point ( or celestial body ).
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Take a look from the other side .
1 kg of burning hydrogen has approximately 120 MJ energy. This is - work in 12000000 kgm. This energy can move 12000000 kg per 1 meter . In a vacuum, this will mean that a lot had the effect of F in 12000000 kg . So when almost isochorically process 1 kg of hydrogen can give a great power - 12000000 kg . ( for more isochorically process (F) increases proportionally) .
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look at the nozzle my motor which moves with acceleration equal to the acceleration of a jet . (Compare with previous models).
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Turns out the same.
If there is a point of reference:
-If acceleration increases the weight of the propellant in a nozzle : ( ma=F ) , F=mav,
-If to consider (F) of thrust identical to (m) mass : (F=m) , F=Fv,
-If not consider (F) of thrust identical to (m) mass : F=m(v*vb) ,that is identical to F=Fv,
-if considered covered by a nozzle distance (s) instead of speed (v) : F=Fs,
and,
If no point of reference:
-transformation of Isobaric process in Isochorically and increases static component of thrust.
Someone may ask, " where does so much energy in the jet stream? . The answer is nowhere. She just used more rationally . Jet stream does not spend its energy on your and other movement . All the energy of fuel is running on the pressure and the last becomes the speed of electromagnetic forces . Electromagnetic forces create acceleration (gravity) which serves as a cap on the path of the jet stream.
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Indeed F thrust can behave identically of the mass?
I think Yes . If you put two trucks that were pulled from the abyss weight 3000kg and engine nozzle thrust 3000kg ,there would be no difference. (if the thrust nozzle is equal to the weight of the mass).
If the driver does not know that pulls from the abyss - in both cases, he will think that this mass 3000 kg . Both cases will be absolutely identical ( energy, velocity and acceleration of the truck, fuel consumption ).
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Could you simple it down a little for me?
What are you proposing? That using the Oberth principle your constant acceleration becomes cheaper than some other when using your design? Or? As far as I get it you have it working at all accelerations, so what makes your design better?
And if so, What is it you think will be giving the Oberth principle a better 'punch'?
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This engine should generate savings of propellant.
I think it can be compared with the internal combustion engine. My engine is used cylinder head and pressure ( more isochoric process), another cylinder head is missing and is used only impulse of jet stream (isobaric process).
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Are you suggesting that by directing a force, working opposite (against) the rockets acceleration, you will get the equivalence of a added mass, that then will add to a higher fuel efficiency, by using the Oberth principle?
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Are you suggesting that by directing a force, working opposite (against) the rockets acceleration, you will get the equivalence of a added mass, that then will add to a higher fuel efficiency, by using the Oberth principle?
F(thrust) = m(mass) + isochoric process ?
Most likely it should be so. But may be the same process.
Don't know.
F(thrust) = m(mass) can check with a simple experiment(with isochoric process more difficult)
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Are you suggesting that by directing a force, working opposite (against) the rockets acceleration, you will get the equivalence of a added mass, that then will add to a higher fuel efficiency, by using the Oberth principle?
F(thrust) = m(mass) + isochoric process ?
Most likely it should be so. But may be the same process.
Don't know.
F(thrust) = m(mass) can check with a simple experiment(with isochoric process more difficult)
The experiment is simple and low cost. Maybe propose it for "Mythbusters" ?
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I am nnot sure I understand this, but the following can be stated in general: Existing spacecraft are launched by multi-stage rockets that harness the fact that energy from a prior stage is transferred kinetically to the fuel in subsequent stages, so that when they finally ignite, they are doing more work on the remaining payload than simply the energy supplied by their own combustion. However, you must have all the necessary early stages in order that the later stages will enjoy this advantage. That still can take a lot of fuel. As long as chemical popellants are the energy source, there are certain limitations. An innovative new way of overcoming such limits is the ion engine. In it, the propellant is not burned, but is electromagnetically accelerated using another source of energy, such as solar panels. These kinds of engines are much more efficient than regular engines, and one such space craft is currently flying and, thanks to the engine, will be able to stop at one asteroid, examine it, and then to on for a second mission to another.
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Many perceive Oberth effect only with move the jet engine (rockets) in a circular orbit. So I suggest the model of my engine with circular motion of jet engine. Maybe it will be more clear what I mean.
The only difference here is what I have instead of the gravity - acceleration (but according to Einstein they are identical).
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I am nnot sure I understand this, but the following can be stated in general: Existing spacecraft are launched by multi-stage rockets that harness the fact that energy from a prior stage is transferred kinetically to the fuel in subsequent stages, so that when they finally ignite, they are doing more work on the remaining payload than simply the energy supplied by their own combustion. However, you must have all the necessary early stages in order that the later stages will enjoy this advantage. That still can take a lot of fuel. As long as chemical popellants are the energy source, there are certain limitations. An innovative new way of overcoming such limits is the ion engine. In it, the propellant is not burned, but is electromagnetically accelerated using another source of energy, such as solar panels. These kinds of engines are much more efficient than regular engines, and one such space craft is currently flying and, thanks to the engine, will be able to stop at one asteroid, examine it, and then to on for a second mission to another.
Yes I agree Oberth effect is really difficult. I think because its mechanism nobody studied in detail ( limited to the formulas and application on the orbital maneuvers) - it happens often ,if something is not clear given the name and measured quantitative part.
I think Oberth effect is the relationship between accelerated jet engine with the power which this acceleration is doing (I don't know examples where someone studied the effect of accelerated jet engine in a closed impulse system on the overall impulse of this system.
My engine can be explained simply - if accelerate jet engine against his thrust , this F thrust is identical to the mass ( if jet engine has traction 3000 kgf this thrust will be to resist acceleration identical mass in 3000 kg.( Oberth m(v*vb), )
Yes electric jet engine has some advantages in comparison with the chemical. But no one ,will not be able to bring the speed of the spacecraft to 100000-200000 km/s . My engine can it.
P.S. I think accelerating electric jet engine against his thrust you can concentrate in its nozzle more propelant and to resolve its main problem.
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I am nnot sure I understand this, but the following can be stated in general: Existing spacecraft are launched by multi-stage rockets that harness the fact that energy from a prior stage is transferred kinetically to the fuel in subsequent stages, so that when they finally ignite, they are doing more work on the remaining payload than simply the energy supplied by their own combustion. However, you must have all the necessary early stages in order that the later stages will enjoy this advantage. That still can take a lot of fuel. As long as chemical popellants are the energy source, there are certain limitations. An innovative new way of overcoming such limits is the ion engine. In it, the propellant is not burned, but is electromagnetically accelerated using another source of energy, such as solar panels. These kinds of engines are much more efficient than regular engines, and one such space craft is currently flying and, thanks to the engine, will be able to stop at one asteroid, examine it, and then to on for a second mission to another.
Yes I agree Oberth effect is really difficult. I think because its mechanism nobody studied in detail ( limited to the formulas and application on the orbital maneuvers) - it happens often ,if something is not clear given the name and measured quantitative part.
Not true. The Oberth effect is well understood and Oberth studied it in detail (hence giving his name to it). Atomic-S is correct: one way of understanding it is as he explained with multi-stage engines. Moreover, even if you don't call it "the Oberth effect," it is automatically accounted for by simply applying Newtonian mechanics to rockets.
Oberth's original writeup exploring this for NASA is here: https://archive.org/details/nasa_techdoc_19720008133
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I am nnot sure I understand this, but the following can be stated in general: Existing spacecraft are launched by multi-stage rockets that harness the fact that energy from a prior stage is transferred kinetically to the fuel in subsequent stages, so that when they finally ignite, they are doing more work on the remaining payload than simply the energy supplied by their own combustion. However, you must have all the necessary early stages in order that the later stages will enjoy this advantage. That still can take a lot of fuel. As long as chemical popellants are the energy source, there are certain limitations. An innovative new way of overcoming such limits is the ion engine. In it, the propellant is not burned, but is electromagnetically accelerated using another source of energy, such as solar panels. These kinds of engines are much more efficient than regular engines, and one such space craft is currently flying and, thanks to the engine, will be able to stop at one asteroid, examine it, and then to on for a second mission to another.
Yes I agree Oberth effect is really difficult. I think because its mechanism nobody studied in detail ( limited to the formulas and application on the orbital maneuvers) - it happens often ,if something is not clear given the name and measured quantitative part.
Not true. The Oberth effect is well understood and Oberth studied it in detail (hence giving his name to it). Atomic-S is correct: one way of understanding it is as he explained with multi-stage engines. Moreover, even if you don't call it "the Oberth effect," it is automatically accounted for by simply applying Newtonian mechanics to rockets.
Oberth's original writeup exploring this for NASA is here: https://archive.org/details/nasa_techdoc_19720008133
Thanks for the link.
I said what Atomic-S is wrong ? That Oberth effect it is not classical mechanics ? What it does not apply in straight-line movement?
If I said it - sorry.
"The Oberth effect is well understood and Oberth studied it in detail " -if so here is my engine, is applicable Oberth effect for my case or not? Where is experimental work with accelerated jet engine? Oberth effect is the change in speed and gravity - in mechanism of both these elements are - acceleration.
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Ok, I think there's a few reasons why your posts haven't gotten much response.
First, posting lots of different posts with different images is going to overwhelm any reader. If you can summarize your point or question in a single, concise post, it's a lot likelier to get responses.
Second, although you may not be able to improve this, I think there's a language barrier. I can't understand much of what you're trying to ask here, so I can't really comment on it.
Coming back to your question about the Oberth effect and gravity: the Oberth effect says, as Atomic-S points out, that it is more efficient to carry fuel with you in multi-stage rockets than not, since fuel moving with you at high speeds has a lot of kinetic energy due to its motion in addition to its chemical potential energy.
Gravity is a separate force in the universe that doesn't have anything to do with the Oberth effect.
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Ok, I think there's a few reasons why your posts haven't gotten much response.
First, posting lots of different posts with different images is going to overwhelm any reader. If you can summarize your point or question in a single, concise post, it's a lot likelier to get responses.
Second, although you may not be able to improve this, I think there's a language barrier. I can't understand much of what you're trying to ask here, so I can't really comment on it.
Coming back to your question about the Oberth effect and gravity: the Oberth effect says, as Atomic-S points out, that it is more efficient to carry fuel with you in multi-stage rockets than not, since fuel moving with you at high speeds has a lot of kinetic energy due to its motion in addition to its chemical potential energy.
Gravity is a separate force in the universe that doesn't have anything to do with the Oberth effect.
Yes JP my English is difficult to name - the language.And I more hope for the pictures.
I agree that is more efficient to carry fuel with you in multi-stage rockets than not, since fuel moving with you at high speeds has a lot of kinetic energy due to its motion in addition to its chemical potential energy.
But this is a very simplified explanation.
1.More chemical potential energy of fuel means more rockets speed against any of the reference system ( how hard I ran around the rocket I won't be able to increase its fuel energy).
2.Chemical potential energy of rocket moving at a uniform speed ,will not differ from the energy of not moving rocket.
To this energy increased need to have some interaction between the reference frame and the rocket (Or she was moving with acceleration).
This interaction canto happen only through gravity or through acceleration. ( according to Einstein and the experiences - there is no difference between moving with acceleration of the reference system and the gravity).
"Gravity is a separate force in the universe that doesn't have anything to do with the Oberth effect"-
Obert effect is (V*Vb) the change of speed - the speed change is always (ACCELERATION).
Obert effect is (V escap)- and this it is impossible to imagine without (GRAVITY).
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I think you're misunderstanding how relativity works. The laws of physics will hold in any reference frame, but this does not mean that the energy or change in energy calculated is identical in any reference frame. Clearly if I run around a stationary rocket (stationary here on earth), I will measure its kinetic energy as changing as my velocity changes. This has no deep physical meaning aside from the fact that I'm running around the rocket.
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I think you're misunderstanding how relativity works. The laws of physics will hold in any reference frame, but this does not mean that the energy or change in energy calculated is identical in any reference frame. Clearly if I run around a stationary rocket (stationary here on earth), I will measure its kinetic energy as changing as my velocity changes. This has no deep physical meaning aside from the fact that I'm running around the rocket.
Yes I don't understand.
-Why measure the energy of rocket on to the system with which it does not interact. (rocket on earth interacts with the gravitational field of the earth that is why we can speak about some relative energy) rocket-earth. But it does not interact with a distant star, and in this case what is the sense of the relative energy of the rocket-star).
Not our imagination defines the appearance of the relative system. It arises where there is energy interaction (gravity, collisions, acceleration another).
-using Oberth effect near the earth, you can increase the speed of a rocket from 10 km/s to 13 km/s (increased speedin in relation not only the earth but also any other point of the universe). Do at such low speeds have such a big impact laws of relativity (they are significant only when v=c)? Of course not.Then than we explain Oberth effect- "hybrid theory of relativity and Newtonian mechanics"?-I think it's wrong.
-Oberth effect without gravity is impossible.And the only thing we know about gravity is that it generates the acceleration or weight.
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Ex. of popular explanations. "(The fuel is going faster, so it gives more thrust. When it has left the ship in the exhaust, the fuel is going, overall, slower. In numerical terms, if you fuel is moving towards the left at 2 km per second, and is ejected to the right at 3 km per second, the overall velocity change is only 1 km per second. The difference between 3 and 1 is given to the ship. So the ship ends up gaining a lot more velocity, but only if the burn happens at the exact moment when the fuel has gained the most velocity from the gravity of the planet)".
– I think this explanation is not complete and therefore wrong., Why?
-.Chemical potential energy of rocket moving at a uniform speed ,will not differ from the energy of not moving rocket.
("but only if the burn happens at the exact moment when the fuel has gained the most velocity from the gravity of the planet. That is why the Oberth manoeuver needs to be done quickly with a powerful acceleration").
Yes, but what is the mechanism?. What exactly is changes in the fuel? : -changing the speed of the jet stream relative to the combustion chamber ? (then there will be a specific change in dynamic and static components of thrust ).- increases resistance to acceleration the particles of propellant ?( then the weight of particles is identical to the mass).
("most velocity from the gravity") – this is not an acceleration?…
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Ok, I think there's a few reasons why your posts haven't gotten much response.
First, posting lots of different posts with different images is going to overwhelm any reader. If you can summarize your point or question in a single, concise post, it's a lot likelier to get responses.
Second, although you may not be able to improve this, I think there's a language barrier. I can't understand much of what you're trying to ask here, so I can't really comment on it.
Coming back to your question about the Oberth effect and gravity: the Oberth effect says, as Atomic-S points out, that it is more efficient to carry fuel with you in multi-stage rockets than not, since fuel moving with you at high speeds has a lot of kinetic energy due to its motion in addition to its chemical potential energy.
Gravity is a separate force in the universe that doesn't have anything to do with the Oberth effect.
Yes JP you're right to understand my question needed to simplify these physical model to one very simple.
Probably easier is impossible.
Far away in space is the space station. At the station there is a Elevator without ceiling and the Elevator shaft is also open to space. On the floor of the Elevator has the ball weighing 1kg . In this Elevator is an astronaut he takes the ball and throws it up with the speed 10 m/s. The ball flies out of the station with the speed 10 m/s. The thrust obtained station from throwing the ball is Ftrast=m*v=10kgf.
This Elevator is also the ability to move up and down with very large accelerations (10000g). The movement of the Elevator up and down with any accelerations and velocities has no impact on the total momentum of the station. He will always be ( 0 ). In the absence of Fthrust the station will make only oscillatory movements.
If the Elevator will be acceleration in 10000g the ball on the floor will have a weight of 10,000kg or 10T. The astronaut will not be able to pick up the ball and throw up. And the astronaut will not withstand this acceleration. Now to throw the ball during acceleration of the lift we need Superman. I.e. this person should be 10,000 times stronger than ordinary cosmonaut. During acceleration Elevator Superman takes the ball with weight 10T and throws it up with the speed in 10 m/s.
Now what may be the pressure on the floor of the Elevator from this shot and accordingly Fthrust ?
Obviously it will be much greater than in the case without acceleration. And it is :– the weight of the ball M=10000 kg, speed 10m/s,.. F thrust = M*v=100000kgf (I know weight not mass, but how differently? ). Do not forget that the total momentum of the system without Fthrust is ( 0 ) and these 100,000kgf will be increase the total momentum of the system?
PS: I see a similarity with Oberth effect.---- But the acceleration of the Elevator will always be time-limited. Choose a while acceleration during which the Elevator will get the speed to 1000 m/s. As now be considered F thrust ?
According to the Oberth formula m(v*vb): ball mass = 1kg, ball speed=10m/s, Elevator speed=1000m/s , F thrust=m(v*vb)=10000kgf
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I have looked through your post and think I am beginning to understand this. When a mass is ejected from a moving vehicle, it will receive more "thrust" than when the same mass is ejected by the same process from the vehicle at rest. Furthermore, according to http://en.wikipedia.org/wiki/Oberth_effect , when that takes place at low gravitational potential, it is more effective than when it takes place at high gravitational potential.
All that is true if it is correctly understood. It is important, however, to understand it correctly. There is one major problem area that can lead to an incorrect understanding, and that is when there is misunderstadning of the difference between velocity, momentum, and acceleration. All three of these quantities measure motion, but they are not identical and do not have identical significances in terms of the physics.
To move a spaceship, you must change its velocity. Velocity = momentum/mass. This is done by expelling exhaust, and due to the conservation of momentum, the change in the vehicle's momentum is equal and opposite to that of the exhaust. Because the exhaust momentum is also mass * velocity, the largest possible velocity (for a given exhaust mass) is what is needed. This is where conventional rockets have limitations because of the limited exhaust velocities chemically possible, but the Oberth Effect allows us to partly get around this by retaining much of the fuel on board prior to burning, which builds up its own momentum, rendering it more effective in an energy sense when it finally does burn.
Now as to the role of gravity in all this: the citation http://en.wikipedia.org/wiki/Oberth_effect does indeed state that the Oberth Effect is more effective on a spacecraft when it is nearer the gravitating body, but we must not misunderstand why. When thus speaking, the cited reference is speaking in terms of a spacecraft moving according to orbital dynamics, and not in terms of one sitting stationary on the launch pad. It is very important we understand that, because only in the case of the orbiting spacecraft is it correct to say that the Oberth Effect increases the effectiveness of fuel. The reason why low gravitational potential increases the effectiveness of the fuel when in orbital motion is that the lower gravitational potential results in a higher orbital velocity at that point. And also, the Oberth Effect will be effective in this situation only if the thrust is in the same direction as the motion of the ship. A spacecraft sitting on the launch pad derives no benefit from the Oberth Effect at the time of launch because it has not yet built up any speed.
Furthermore, even when the space craft is orbiting and is at low potential and derives gain from the Oberth Effect, this gain is in kinetic energy, not speed and not thrust. The change of speed produced by the Oberth Effect when orbiting at the low point in its orbit will be the same as the change in speed derived when orbiting in the high point of the orbit, although the change in kinetic energy at the low point will be greater because kinetic energy = 1/2 m*v2. That does not mean, however, that the Oberth Effect is of no value. The ship has still gained more speed for the fuel spent than it could have under different circumstances.
I realize that the foregoing probably is considerably less than a full explanation of all this, but I wish to move on to the question of engines. I do not fully understand your engine diagrams, but it appears that it has something to do with designing the engine to pre-accelerate the fuel to a high speed before igniting it, by putting it through a turbine, and that, because the fuel now moves, prior to combustion, faster with respect to the rocket than it previously did, there should be greater thrust generated.
I believe that the answer to that is that yes, this effect will happen if we have the right design. It appears from your diagrams that you would place the nozzles on a spinning arm, or set of arms, so that when a nozzle is moving rearward, it would then be fired, resulting in a higher exhaust velocity and greater thrust. I believe that that analysis is incorrect when expressed in that way, but that the correct explanation is that when the nozzle fires, the thrust it generates is no different than it would under any other circumstance, but that the thrust is harnessed differently. Being on the moving arm, when it fires, the arm adds not thrust but work to the process by pushing against the nozzle thrust while simultaneously pushing in the opposite direction against the spacecraft frame, increasing the distance between both under the influence of the nozzle thrust, which has the effect of doing extra work on the spacecraft frame over and above the work that the nozzle exhaust is doing.
So yes, the scheme seems able to be able to derive greater momentum change of the spacecraft per unit of fuel expended that can a simple rocket nozzle mounted directly to the frame. However, there are certain complications. Specifically, in order to keep the arm moving during this process, there must be an additional source of motive power, otherwise the thrust would cause it to stop. Where will that power come from? An internal combustion engine that burns extra fuel is one possibility, and I do not know whether fuel burned this way would be more efficient than the same fuel burned in an extra fixed nozzle used instead (although I suspect it may well be). We are not limited to using burned fuel for this purpose; the arm could be driven by an electric drive powered by solar cells or a nuclear generator.
So yes, I think you are right that an engine based on this principle may be capable of more efficient use of fuel, and greater range, than conventional rockets. Just how much better is hard to know without doing a lot of detailed calculations.
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Upon further considering this problem, it occurs to me that an essential part of the process is what happens to the fuel between the time that it leaves the tank and reaches the nozzle. Because of the spinning arm, its momentum changes during the time that it travels from the pivot point to the nozzle. That change would be substantial in this situation because the arm would have to be spinning quite rapidly and/or be quite long for the effect to be significant. During the time when the fuel is transiting along the arm from pivot to nozzle, its inertia tends to retard the arm's motion (as seen from aboard the craft), which is compensated by the motive power driving the arm. In the process of thus compensating, the motor that drives the arm experiences thrust generated by the unburned fuel's change of momentum as it travels along the arm, and this is where the system derives the extra propulsion that it generates.
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Thank Atomic-S for trying to understand this engine and for a very good comment. Just want to clarify some important details. Burning of the propellant occurs simultaneously with the acceleration of the nozzle. Or on models with Elevator throw the ball occurs during the acceleration of the Elevator (to throw away not only mass, but also increased the weight of propellant).
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I think this is Oberth effect. But today it is used only reverse view .When the spacecraft passes periapsis gravity celestial body brake the spacecraft ( the bigger the ship's speed and gravity the more will be this brake and the more engine thrust).
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I think Oberth effect on the orbit can be compared with swings. Appears in periapsis when appears the weight of burning fuel.
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Oberth effect on the multi-stage rocket (change of acceleration).
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The passage periapsis of the rocket can be compared with the passage obstacles of bullet.
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The increase of kinetic energy in Obert effect does not arise from any relative velocities but from the increased potential energy of the fuel in nozzle. Oberth effect are the reflection of the law of energy conservation.
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I am still a bit confused on your physics. Going over one of your diagrams, I have found some errors, and have so indicated:
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Having carefully studied this diagram, I think that it is not correct unless certain phenomena are taken into account, which do not appear to be taken into account here. We must not confuse thrust and mass. They are not the same thing. In this diagram, if the extra force created for the purpose of separating the outer reference frame (that of the ship) from the inner reference frame (the nozzle carriage or "elevator") is less than the thrust being generated by the combustion in the nozzle, the two reference frames will not separate at all, but the one will ram into the other, locking to it and giving the thrust for the simple (upper diagram) situation. If the separation force is made greater than the nozzle thrust, the reference frames will separate, but the acceleration of the nozzle will be less than before because it is experiencing conflicting forces: that of its own gasses and that of the separation force, which are opposing. The ship itself will receive only the separation force, which is equal and opposite in the two directions it acts, which might well be greater than the nozzle thrust, however for that to happen, the acceleration of the nozzle must be a finite number, requiring that the nozzle mass be greater than zero. Your diagrams no where mention the mass of the nozzle (or of the elevator in the diagrams having elevators), but it actually matters.
I believe you have incorrectly analyzed the problem. Your proposed engine may work, but for different reasons than you have stated. I however strongly suspect that an essential feature of the problem is that for the engine to do so, it must be furnished with additional power over and above what is generated by the combustion of the fuel being burned in the nozzle. I don't quite understand your design, but it seems that you have provided for such additional power through a magnetic coil, the exact function of which I don't understand, but based on what I havde said, the energetics would seem to be valid, even if your analysis of them is not..
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Sorry there are errors in my picture. It's because I'm not a student wants to get the score for the correctness of the calculation. For me important proportions and relationships.
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Having carefully studied this diagram, I think that it is not correct unless certain phenomena are taken into account, which do not appear to be taken into account here. We must not confuse thrust and mass. They are not the same thing. In this diagram, if the extra force created for the purpose of separating the outer reference frame (that of the ship) from the inner reference frame (the nozzle carriage or "elevator") is less than the thrust being generated by the combustion in the nozzle, the two reference frames will not separate at all, but the one will ram into the other, locking to it and giving the thrust for the simple (upper diagram) situation. If the separation force is made greater than the nozzle thrust, the reference frames will separate, but the acceleration of the nozzle will be less than before because it is experiencing conflicting forces: that of its own gasses and that of the separation force, which are opposing. The ship itself will receive only the separation force, which is equal and opposite in the two directions it acts, which might well be greater than the nozzle thrust, however for that to happen, the acceleration of the nozzle must be a finite number, requiring that the nozzle mass be greater than zero. Your diagrams no where mention the mass of the nozzle (or of the elevator in the diagrams having elevators), but it actually matters.
I believe you have incorrectly analyzed the problem. Your proposed engine may work, but for different reasons than you have stated. I however strongly suspect that an essential feature of the problem is that for the engine to do so, it must be furnished with additional power over and above what is generated by the combustion of the fuel being burned in the nozzle. I don't quite understand your design, but it seems that you have provided for such additional power through a magnetic coil, the exact function of which I don't understand, but based on what I havde said, the energetics would seem to be valid, even if your analysis of them is not..
Really I guess what F traction in this case (acceleration nozzle or Elevator) is equivalent to the mass ,or weight of burning fuel is equivalent to the mass of that fuel. Also assume that this equivalence is the mechanism of Oberth effect.
Equivalence principle:
(Inertial mass).(Acceleration) =(Intensity of the gravitational field).(Gravitational mass),
everyone agrees.
But,
(Inertial mass)=(Gravitational mass) .......m identical W
and
(Acceleration) =(Intensity of the gravitational field).........a identical gravitational field,
all disagree.
Yes maybe I am wrong but I do not find clear explanations or similarity in the ordinary course of physics. How to calculate it?
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Having carefully studied this diagram, I think that it is not correct unless certain phenomena are taken into account, which do not appear to be taken into account here. We must not confuse thrust and mass. They are not the same thing. In this diagram, if the extra force created for the purpose of separating the outer reference frame (that of the ship) from the inner reference frame (the nozzle carriage or "elevator") is less than the thrust being generated by the combustion in the nozzle, the two reference frames will not separate at all, but the one will ram into the other, locking to it and giving the thrust for the simple (upper diagram) situation. If the separation force is made greater than the nozzle thrust, the reference frames will separate, but the acceleration of the nozzle will be less than before because it is experiencing conflicting forces: that of its own gasses and that of the separation force, which are opposing. The ship itself will receive only the separation force, which is equal and opposite in the two directions it acts, which might well be greater than the nozzle thrust, however for that to happen, the acceleration of the nozzle must be a finite number, requiring that the nozzle mass be greater than zero. Your diagrams no where mention the mass of the nozzle (or of the elevator in the diagrams having elevators), but it actually matters.
I believe you have incorrectly analyzed the problem. Your proposed engine may work, but for different reasons than you have stated. I however strongly suspect that an essential feature of the problem is that for the engine to do so, it must be furnished with additional power over and above what is generated by the combustion of the fuel being burned in the nozzle. I don't quite understand your design, but it seems that you have provided for such additional power through a magnetic coil, the exact function of which I don't understand, but based on what I havde said, the energetics would seem to be valid, even if your analysis of them is not..
Yes, you can consider rocket engine as a material object from which to repell but which are not repelled. More correct ? Yes if his thrust is very large and push mass is very small. But and here is the question? How will resist to the external force the working rocket engine what will be its inertness?
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Having carefully studied this diagram, I think that it is not correct unless certain phenomena are taken into account, which do not appear to be taken into account here. We must not confuse thrust and mass. They are not the same thing. In this diagram, if the extra force created for the purpose of separating the outer reference frame (that of the ship) from the inner reference frame (the nozzle carriage or "elevator") is less than the thrust being generated by the combustion in the nozzle, the two reference frames will not separate at all, but the one will ram into the other, locking to it and giving the thrust for the simple (upper diagram) situation. If the separation force is made greater than the nozzle thrust, the reference frames will separate, but the acceleration of the nozzle will be less than before because it is experiencing conflicting forces: that of its own gasses and that of the separation force, which are opposing. The ship itself will receive only the separation force, which is equal and opposite in the two directions it acts, which might well be greater than the nozzle thrust, however for that to happen, the acceleration of the nozzle must be a finite number, requiring that the nozzle mass be greater than zero. Your diagrams no where mention the mass of the nozzle (or of the elevator in the diagrams having elevators), but it actually matters.
I believe you have incorrectly analyzed the problem. Your proposed engine may work, but for different reasons than you have stated. I however strongly suspect that an essential feature of the problem is that for the engine to do so, it must be furnished with additional power over and above what is generated by the combustion of the fuel being burned in the nozzle. I don't quite understand your design, but it seems that you have provided for such additional power through a magnetic coil, the exact function of which I don't understand, but based on what I havde said, the energetics would seem to be valid, even if your analysis of them is not..
On my figure, the coil means a linear motor and has only one function-to accelerate the rocket engine. But I think it is better to accelerate the jet engine with railgun (coil can not withstand high accelerations).
Yes, the mass of the rocket engine will have a value (its acceleration will consume energy) but it will not affect the total momentum of the system.
I think this engine can be interpreted as the work or power (i.e. how to start Oberth effect)
P.S.I replaced the images with Elevator.
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As will be burning fuel when nozzle acceleratingin in 30000g or 300000m/s2 (acceleration of normal railgun) ?
If the fuel acceleration is approximately equal to the acceleration of nozzle-I think that will be a nuclear fusion reaction similar to the reaction of the white dwarf.
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I think if make this engine with the nuclear fusion reaction - will look something like this.
If without nuclear fusion reaction-- will look too, something like this but without nozzle coil.
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Perhaps more relevant is if consider a similar system from a position of (N) power.
(With position (N) and (A) starts and the explanation of Oberth effect).
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It is clear that, using your rail gun design as an example, that if you attach, to the movable arm, an engine generating thrust in the opposite direction, then the acceleration of the arm-engine system will be retarded to a lesser value than it would have had if the engine were not operating. That is because with the engine operating, the engine-arm system is affected by opposing forces: That of the magnetic thrust from the rails and that of the rocket thrust from the engine; leaving a lesser net force. This, however, would not reduce the overall momentum imparted to the ship, but would rather increase it. You are correct about that. The reason it will increase it, is that the thrust being received by the ship is simply that of the electromagnetic system, and that will be the same whether the engine is firing or not (to a first approximation, neglecting possible other complications.) However, the time during which the arm-engine system will remain between the rails will be greater when the engine is firing, due to the conflicting forces received by that system, and because it remains between the rails longer, the magnetic force has a longer period of time to act on the ship frame, resulting in a greater overall change in the ship's momentum. I believe you are correct in concluding that this system will generate greater overall propulsion, although I am still not sure your mathemtics is right, because you said
(F) thrust of rocket engine behaves identically to the (m) mass (to get the same speed they require the same amount of power.
I believe you are erroneously here equating thrust and mass, and they will not behave the same way.
Nevertheless, to be a practical propulsion system, your design requires that once the arm-engine system reaches the end of the rails, it must be returned to its starting position to be fired again. That require a reverse force to draw it back into the ship. Correspondingly, the ship will receive a reverse force, which will undo some of the propulsion generated. However, because the gasses that were expelled during the first cycle will not be returned, the return mass is less than the initial mass, and will not fully cancel the original propulsion. Then the engine can be fired again and expelled as before, creating another cycle of thrust. The net result of all this is that the average exhaust velocity from the ship will be greater than with simple combustion, and the propulsion derived from the fuel will be greater than the propulsion using burning only. However, it is necessary to furnish the electrical power to operate the railgun. You will need some source for that. Also, the magnitude of the improved performance in excess of a simple rocket may not be what you have calculated, because I am not sure you are doing it correctly, although I still don't quite understand it.
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Yes, this proposed system will be unbalanced by the following obvious reasons:
1. The presence of fuel in a jet engine on the repulsion trajectory, and its absence (or fewer ) on the returning trajectory .
2. Increase the speed of the working substance ( V working substance + V jet engine).
This is an obvious facts that do not require validation. Based on these two factors ,increase the total momentum of the system does not justify the additional mass associated with the construction of the engine and power system.
But there are two another possible factor:
3. Increase the static component of the thrust of jet engine at high accelerations .
4. Presumably appearance of the Obert effect .
The last two factors is possible and I try to pay attention to them.
They exist or not can be confirmed or refuted experimentally. Most likely they don't exist. But the question is ,that if these two factors will manifest (this can be checked with a model jet engine and rubber harness )?
The answer: the chance to make sub light engine (interstellar) at the current level of science and technology.
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It is clear that, using your rail gun design as an example, that if you attach, to the movable arm, an engine generating thrust in the opposite direction, then the acceleration of the arm-engine system will be retarded to a lesser value than it would have had if the engine were not operating. That is because with the engine operating, the engine-arm system is affected by opposing forces: That of the magnetic thrust from the rails and that of the rocket thrust from the engine; leaving a lesser net force. This, however, would not reduce the overall momentum imparted to the ship, but would rather increase it. You are correct about that. The reason it will increase it, is that the thrust being received by the ship is simply that of the electromagnetic system, and that will be the same whether the engine is firing or not (to a first approximation, neglecting possible other complications.) However, the time during which the arm-engine system will remain between the rails will be greater when the engine is firing, due to the conflicting forces received by that system, and because it remains between the rails longer, the magnetic force has a longer period of time to act on the ship frame, resulting in a greater overall change in the ship's momentum. I believe you are correct in concluding that this system will generate greater overall propulsion, although I am still not sure your mathemtics is right, because you said (F) thrust of rocket engine behaves identically to the (m) mass (to get the same speed they require the same amount of power.
I believe you are erroneously here equating thrust and mass, and they will not behave the same way.
Nevertheless, to be a practical propulsion system, your design requires that once the arm-engine system reaches the end of the rails, it must be returned to its starting position to be fired again. That require a reverse force to draw it back into the ship. Correspondingly, the ship will receive a reverse force, which will undo some of the propulsion generated. However, because the gasses that were expelled during the first cycle will not be returned, the return mass is less than the initial mass, and will not fully cancel the original propulsion. Then the engine can be fired again and expelled as before, creating another cycle of thrust. The net result of all this is that the average exhaust velocity from the ship will be greater than with simple combustion, and the propulsion derived from the fuel will be greater than the propulsion using burning only. However, it is necessary to furnish the electrical power to operate the railgun. You will need some source for that. Also, the magnitude of the improved performance in excess of a simple rocket may not be what you have calculated, because I am not sure you are doing it correctly, although I still don't quite understand it.
Without mathematics.Imagine yourself instead of the person in the picture and try to understand what he would push these carts (in what conditions it will be equally hard to push two carts?).
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I'll try to explain in more detail. The man pushes the nozzle against the force of thrust. Physically, it is difficult for him to do. If he pushes the nozzle certain distance within a certain time, he spends some power. The sooner he does it, the more he gets tired (consumes more power).This power is transferred to his feet on the ground surface or to another mass (for example a moving platform).
The same thing happens if someone pushes some mass which applies a very small acceleration. If this acceleration not exist ,that people will push any weight without power consumption.
In this case, the equivalence between (F) and (m) will not be ,the nozzle will resist movement and the mass will not. I.e. this equivalence will shift giving speed only the mass but not the nozzle. But this is a perfect case because in reality, it is necessary to give first some acceleration to get the velocity (which occurs when nozzle is in acceleration I described at the beginning). If such an ideal case was that ,the system could unbalance even more than the equivalence of (F) and (m).
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If the engine will not work, the total momentum of the system always be zero.
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Sublight spaceship with the engine on Oberth effect,will look like this-
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I think this engine will look something like this .And will have a 2 stroke of work: