Intercontinental ballistic missile

Quote from: Stash on January 04, 2019, 02:58:32 AM

Quote from: sceptimatic on January 04, 2019, 02:22:05 AM

Less resistance above means less resistance below, meaning the max thrust would make the rocket lose speed and not keep a steady mph/mps IF the rocket didn't shed some of its mass...but it does. It sheds its fuel which lessens it's mass and keeps the thrust to mass ratio steady as it moves into thinner atmosphere.

Which, logically, would mean, less resistance above (good, easier to push through), it sheds it's fuel, lessening the mass of the object, it's thrust to mass ratio is actually greater. Not steady or equal. It's lighter, has less atmospheric resistance, yet still has its same full thrust as it did when it was heavier. Hence, acceleration. How is that logic flawed? The rocket accelerates until it's fuel is spent. That's logic and quite possibly rocket science.

As I explained earlier. It might have less atmosphere to push through but it also has less to push against. It counteracts and keeps a steady mph/mps. Or speed.

The problem with all of this, and one of the many things you've never explained, is that you falsely assume that thrust from the rocket pushes against the atmosphere.  Something that is contrary to reality and that you can't support.  However, you can test it but we all know you never will so there's that.

AAMOF, the atmosphere actually acts against the motion of the rocket.  The exhausting gases exerts a force on the bottom of the rocket and that's the only thing that makes it move.  Since you acknowledge that momentum exists then you have to agree that this is how it works.

Using the septi-playbook here's an analogy for you.

I'm swinging on a rope and slam into you.  You are going to go move and it has nothing to do with the atmosphere.

Mike

Quote from: Themightykabool on January 04, 2019, 04:13:09 AM

Ok boyos
Scepi is using alternative physics.
Based on his definiton of thrust -
I believe He equates thrust as energy.
So in his mind whne fuel is spent = no more energy.
When his chemical potential energy converted to kinetic, then reaching a max vertical potential energy, yes, the rocket stops "dead".

Maybe thats what hes on about.

Of course this fool likes to redefine words then gets upset when no one understands him...

Scepti
Yes no?

If you can tell me how you can get thrust without using energy then I'm all ears.

Ah
But see we (indotrinated physics people) are basically using different terminology.
We are simply communicating in english.
Simply when max thrust is spent tue chemcial energy is converted to kinetic 1/2mv^2.
The velocity factor exists as m/s.
Decellerating at a rate of drag+9.81m/s^2.
This forward movement continues until velocity appraoches zero.
That is the dead stop.
If you paid attention to the bank and car analogy, the math is greatly overly simplified so this stands out.
Pay attention to the basics and youll get there.
Its simple math.

But regardless of us, As defiend above is this what you believe?

Quote from: Themightykabool on January 04, 2019, 04:13:09 AM

Ok boyos
Scepi is using alternative physics.
Based on his definiton of thrust -
I believe He equates thrust as energy.
So in his mind whne fuel is spent = no more energy.
When his chemical potential energy converted to kinetic, then reaching a max vertical potential energy, yes, the rocket stops "dead".

Maybe thats what hes on about.

Of course this fool likes to redefine words then gets upset when no one understands him...

Scepti
Yes no?

If you can tell me how you can get thrust without using energy then I'm all ears.

In our world
Thrust = force                   
= mass x accell.

Enegy = force x distance
= mass x accell x distance.

Power = force x distance / second
= mass x accell x distance / second

Your world
Thrust = energy = power

The problem with all of this, and one of the many things you've never explained, is that you falsely assume that thrust from the rocket pushes against the atmosphere.  Something that is contrary to reality and that you can't support.  However, you can test it but we all know you never will so there's that.

The thrust from the rocket does push against the atmosphere which pushes back.

AAMOF, the atmosphere actually acts against the motion of the rocket.  The exhausting gases exerts a force on the bottom of the rocket and that's the only thing that makes it move.

Explain to me how the burning rocket fuel can exert a force on the bottom of the rocket and managed to push it up. It's ridiculous and it baffles me why people fall for this clear nonsense.

  Since you acknowledge that momentum exists then you have to agree that this is how it works.

Using the septi-playbook here's an analogy for you.

I'm swinging on a rope and slam into you.  You are going to go move and it has nothing to do with the atmosphere.

Mike

I am the atmosphere and you are the rocket fuel.

Quote from: sceptimatic on January 04, 2019, 04:32:41 AM

Quote from: Themightykabool on January 04, 2019, 04:13:09 AM

Ok boyos
Scepi is using alternative physics.
Based on his definiton of thrust -
I believe He equates thrust as energy.
So in his mind whne fuel is spent = no more energy.
When his chemical potential energy converted to kinetic, then reaching a max vertical potential energy, yes, the rocket stops "dead".

Maybe thats what hes on about.

Of course this fool likes to redefine words then gets upset when no one understands him...

Scepti
Yes no?

If you can tell me how you can get thrust without using energy then I'm all ears.

In our world
Thrust = force                   
= mass x accell.

Enegy = force x distance
= mass x accell x distance.

Power = force x distance / second
= mass x accell x distance / second

Your world
Thrust = energy = power

Look up my meanings and you'll see a lot more than you're making out.

You are not qualified to change the definitions.

Look up what they posted and try to learn something.

Scepti never seems to get bored of these games.

You are not qualified to change the definitions.

Look up what they posted and try to learn something.

But Unfortunately if we want our discussion to go anywhere we have to start speaking scepinese.

Quote from: Themightykabool on January 04, 2019, 04:47:28 AM

Quote from: sceptimatic on January 04, 2019, 04:32:41 AM

Quote from: Themightykabool on January 04, 2019, 04:13:09 AM

Ok boyos
Scepi is using alternative physics.
Based on his definiton of thrust -
I believe He equates thrust as energy.
So in his mind whne fuel is spent = no more energy.
When his chemical potential energy converted to kinetic, then reaching a max vertical potential energy, yes, the rocket stops "dead".

Maybe thats what hes on about.

Of course this fool likes to redefine words then gets upset when no one understands him...

Scepti
Yes no?

If you can tell me how you can get thrust without using energy then I'm all ears.

In our world
Thrust = force                   
= mass x accell.

Enegy = force x distance
= mass x accell x distance.

Power = force x distance / second
= mass x accell x distance / second

Your world
Thrust = energy = power

Look up my meanings and you'll see a lot more than you're making out.

Rabs reposted several times.
Youve made no updates.
And realize im the only one tryig to keep discussion within your relm.

If you havent noticed, everyone else is soeaking english and Youre arguing about hugh's on first.

Sceptimatic, do you think there is a difference in how a rocket engine works and a propeller on a plane works in providing thrust?  Please explain to us how each you of engine is providing thrust and how each would accelerate and maintain velocity in your own words if you can.   I think this is the source of much of the confusion here.

Quote from: MicroBeta on January 04, 2019, 04:35:32 AM

The problem with all of this, and one of the many things you've never explained, is that you falsely assume that thrust from the rocket pushes against the atmosphere.  Something that is contrary to reality and that you can't support.  However, you can test it but we all know you never will so there's that.

The thrust from the rocket does push against the atmosphere which pushes back.

Quote from: MicroBeta

AAMOF, the atmosphere actually acts against the motion of the rocket.  The exhausting gases exerts a force on the bottom of the rocket and that's the only thing that makes it move.

Explain to me how the burning rocket fuel can exert a force on the bottom of the rocket and managed to push it up. It's ridiculous and it baffles me why people fall for this clear nonsense.

It boggles the mind that you believe the engine exhaust exerts zero force on the rocket...boggles the fuckin’ mind.

It’s only ridiculous to you because you don’t know what you’re talking about.  It’s not just burning rocket fuel.    If want you want to know why, look up venturies and nozzles for yourself because I’m tired of explaining shit to people who blindly dismiss what they don’t understand and have never tested.

Quote from: MicroBeta

  Since you acknowledge that momentum exists then you have to agree that this is how it works.

Using the septi-playbook here's an analogy for you.

I'm swinging on a rope and slam into you.  You are going to go move and it has nothing to do with the atmosphere.

Mike

I am the atmosphere and you are the rocket fuel.

**sigh** you completely missed the point.  I’m the reaction force of the exhausting gases and you’re the rocket but we’ll ignore that for now.

IIUC, here's a synopsis of your premise of how denpressure effects vertical acceleration of a rocket.

- The density of the atmosphere (molecule stacking or however you define it) decreases with altitude.
- The force required for a rocket to ascend through the less dense atmosphere decreases but there is also a corresponding decrease of the reaction force due to thrust on the same less dense atmosphere.
- Therefore, the constant thrust, decreasing mass, and change in density during vertical ascent are always balanced so acceleration is exactly zero.

There are a few major problems with this reasoning.  The claim that a rocket can't accelerate must be subject to the following:

1. The effects of density versus altitude must be quantified.   
2. Variables within the system must be accounted for:
    a. The magnitude of thrust can vary from rocket to rocket.
    b. e.g. Two identical model rockets can have engines with identical size and weight but different thrust values.
    c. The rate at which fuel, and thus the corresponding decrease in mass, varies from engine to engine.
    d. Atmospheric pressure and density versus altitude is not linear.
    e. In taller rockets the density the rocket is pushing into and against may not be equal.
    f. Thrust to weight ratio varies from rocket to rocket

In summary:

1. The effect of denpressure vs altitude is not quantified.
2. The change in density of the atmosphere vs altitude is non-linear.
3. The magnitude of thrust and thrust to weight ratio varies between rockets.
4. The rate of change of the mass varies between rockets.

Working entirely within the denpressure model and considering the variables outlined above, at a minimum the following outcomes are possible:

1. If the magnitude of thrust and fuel consumption are balanced by the change in atmospheric density, it is possible for a rocket to have zero acceleration during vertical ascent.
2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

If we take all the variables into account and working within denpressure, it is possible to have zero vertical acceleration or a constant/variable vertical acceleration throughout ascent.  And, if I’m honest about it, these variables also imply that at some point in its ascent it should be possible for density to overcome thrust/fuel consumption and the rocket will decelerate (negative or downward acceleration) to the point where the rocket reaches equilibrium and not climb or fall until thrust is cutoff or increased.

Tthe point is that without quantifying denpressure and accounting for the variables between rockets, you can’t definitively say what the effect on the vertical acceleration will be.  A zero, a positive, or a negative acceleration should all be possible but there’s no way to know.

Mike

Guys
Note he never uses numbers or units.
He was given two very basic anaolgies and he dismissed them - why? -because he doesnt get numbers.
Game over.

Sceptimatic, do you think there is a difference in how a rocket engine works and a propeller on a plane works in providing thrust?  Please explain to us how each you of engine is providing thrust and how each would accelerate and maintain velocity in your own words if you can.   I think this is the source of much of the confusion here.

There's no confusion on my part.
Every rocket, whether it's a jet or a car use atmosphere to thrust against to gain momentum.
No external atmosphere and no movement. It's that simple.


However, I'd still love to know how a supposed ballistic missile of supposed 20 odd feet length can be pushed from deep water (100 feet or so) by compressed air to actually leap from it, clear by a few feet and then ignite and thrust to its target.

We seem to be drifting away from this.

Guys
Note he never uses numbers or units.
He was given two very basic anaolgies and he dismissed them - why? -because he doesnt get numbers.
Game over.

That's my point.  If nothing is quantified then the accelerations possibilities become variable.  Realistically, even if denpressure was quantified, there are too many variables for rockets to be able to say they all have the same outcome.

Mike

It boggles the mind that you believe the engine exhaust exerts zero force on the rocket...boggles the fuckin’ mind.

It’s only ridiculous to you because you don’t know what you’re talking about.  It’s not just burning rocket fuel.    If want you want to know why, look up venturies and nozzles for yourself because I’m tired of explaining shit to people who blindly dismiss what they don’t understand and have never tested.



IIUC, here's a synopsis of your premise of how denpressure effects vertical acceleration of a rocket.

- The density of the atmosphere (molecule stacking or however you define it) decreases with altitude.
- The force required for a rocket to ascend through the less dense atmosphere decreases but there is also a corresponding decrease of the reaction force due to thrust on the same less dense atmosphere.
- Therefore, the constant thrust, decreasing mass, and change in density during vertical ascent are always balanced so acceleration is exactly zero.

There are a few major problems with this reasoning.  The claim that a rocket can't accelerate must be subject to the following:

1. The effects of density versus altitude must be quantified.   
2. Variables within the system must be accounted for:
    a. The magnitude of thrust can vary from rocket to rocket.
    b. e.g. Two identical model rockets can have engines with identical size and weight but different thrust values.
    c. The rate at which fuel, and thus the corresponding decrease in mass, varies from engine to engine.
    d. Atmospheric pressure and density versus altitude is not linear.
    e. In taller rockets the density the rocket is pushing into and against may not be equal.
    f. Thrust to weight ratio varies from rocket to rocket

In summary:

1. The effect of denpressure vs altitude is not quantified.
2. The change in density of the atmosphere vs altitude is non-linear.
3. The magnitude of thrust and thrust to weight ratio varies between rockets.
4. The rate of change of the mass varies between rockets.

Working entirely within the denpressure model and considering the variables outlined above, at a minimum the following outcomes are possible:

1. If the magnitude of thrust and fuel consumption are balanced by the change in atmospheric density, it is possible for a rocket to have zero acceleration during vertical ascent.


2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

If we take all the variables into account and working within denpressure, it is possible to have zero vertical acceleration or a constant/variable vertical acceleration throughout ascent.  And, if I’m honest about it, these variables also imply that at some point in its ascent it should be possible for density to overcome thrust/fuel consumption and the rocket will decelerate (negative or downward acceleration) to the point where the rocket reaches equilibrium and not climb or fall until thrust is cutoff or increased.

Tthe point is that without quantifying denpressure and accounting for the variables between rockets, you can’t definitively say what the effect on the vertical acceleration will be.  A zero, a positive, or a negative acceleration should all be possible but there’s no way to know.

Mike

At least you're taking notice. I commend you for that.
Just one thing though and it is nit picking but I feel I must do it. It this piece what you said: 2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Quote from: MicroBeta on January 04, 2019, 07:17:54 AM

It boggles the mind that you believe the engine exhaust exerts zero force on the rocket...boggles the fuckin’ mind.

It’s only ridiculous to you because you don’t know what you’re talking about.  It’s not just burning rocket fuel.    If want you want to know why, look up venturies and nozzles for yourself because I’m tired of explaining shit to people who blindly dismiss what they don’t understand and have never tested.



IIUC, here's a synopsis of your premise of how denpressure effects vertical acceleration of a rocket.

- The density of the atmosphere (molecule stacking or however you define it) decreases with altitude.
- The force required for a rocket to ascend through the less dense atmosphere decreases but there is also a corresponding decrease of the reaction force due to thrust on the same less dense atmosphere.
- Therefore, the constant thrust, decreasing mass, and change in density during vertical ascent are always balanced so acceleration is exactly zero.

There are a few major problems with this reasoning.  The claim that a rocket can't accelerate must be subject to the following:

1. The effects of density versus altitude must be quantified.   
2. Variables within the system must be accounted for:
    a. The magnitude of thrust can vary from rocket to rocket.
    b. e.g. Two identical model rockets can have engines with identical size and weight but different thrust values.
    c. The rate at which fuel, and thus the corresponding decrease in mass, varies from engine to engine.
    d. Atmospheric pressure and density versus altitude is not linear.
    e. In taller rockets the density the rocket is pushing into and against may not be equal.
    f. Thrust to weight ratio varies from rocket to rocket

In summary:

1. The effect of denpressure vs altitude is not quantified.
2. The change in density of the atmosphere vs altitude is non-linear.
3. The magnitude of thrust and thrust to weight ratio varies between rockets.
4. The rate of change of the mass varies between rockets.

Working entirely within the denpressure model and considering the variables outlined above, at a minimum the following outcomes are possible:

1. If the magnitude of thrust and fuel consumption are balanced by the change in atmospheric density, it is possible for a rocket to have zero acceleration during vertical ascent.


2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

If we take all the variables into account and working within denpressure, it is possible to have zero vertical acceleration or a constant/variable vertical acceleration throughout ascent.  And, if I’m honest about it, these variables also imply that at some point in its ascent it should be possible for density to overcome thrust/fuel consumption and the rocket will decelerate (negative or downward acceleration) to the point where the rocket reaches equilibrium and not climb or fall until thrust is cutoff or increased.

Tthe point is that without quantifying denpressure and accounting for the variables between rockets, you can’t definitively say what the effect on the vertical acceleration will be.  A zero, a positive, or a negative acceleration should all be possible but there’s no way to know.

Mike

At least you're taking notice. I commend you for that.
Just one thing thought and it is nit picking but I feel I must do it. It this piece what you said: 2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Quoted to preserve the stupidity.

A Bugatti Chiron does 0-60 in 2.5 seconds. Do you think it does 200 to 260 in 2.5 seconds?
No. Decreaseing acceleration.

Ho Lee Fuk




 

Quote from: JCM on January 04, 2019, 06:55:23 AM

Sceptimatic, do you think there is a difference in how a rocket engine works and a propeller on a plane works in providing thrust?  Please explain to us how each you of engine is providing thrust and how each would accelerate and maintain velocity in your own words if you can.   I think this is the source of much of the confusion here.

There's no confusion on my part.

Youre right.
You are definitely NOT confused.

https://goo.gl/images/umceXS

Quote from: sceptimatic on January 04, 2019, 07:39:06 AM

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Quoted to preserve the stupidity.

A Bugatti Chiron does 0-60 in 2.5 seconds. Do you think it does 200 to 260 in 2.5 seconds?
No. Decreaseing acceleration.

Ho Lee Fuk

0-60 in 2.5 seconds is acceleration.

200 to 260 in 2.5 seconds is acceleration.

What's your issue?

Quote from: sokarul on January 04, 2019, 07:46:19 AM

Quote from: sceptimatic on January 04, 2019, 07:39:06 AM

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Quoted to preserve the stupidity.

A Bugatti Chiron does 0-60 in 2.5 seconds. Do you think it does 200 to 260 in 2.5 seconds?
No. Decreaseing acceleration.

Ho Lee Fuk

0-60 in 2.5 seconds is acceleration.

200 to 260 in 2.5 seconds is acceleration.

What's your issue?

He's pointing out that is decreasing acceleration.

<snip>
However, I'd still love to know how a supposed ballistic missile of supposed 20 odd feet length can be pushed from deep water (100 feet or so) by compressed air to actually leap from it, clear by a few feet and then ignite and thrust to its target.

We seem to be drifting away from this.

It is a very simple process so I do not understand what your problem is.  There’s nothing technically complicated about it.  AAMOF, getting the thing airborne was one of more trivial engineering aspects of launching a missile.  The tough part was figuring out how to get it to its target.

High pressure gas is rapidly applied to the stern of the missile and it is impulse out of the tube.  Just like a dart from a blowgun.  After it breaches the surface the missile senses the change in direction of acceleration and fires the engines and off it goes.  The ability to sense its change in direction works on the same principles as the accelerometers in your cell phone or the system that deploys the airbags in your car. 

It’s nothing but a vertically launched torpedo...except you can drain and reload the torpedo tube.  The torpedo is impulses out of the tube by compressed gas.  As it enters the water it decelerates rapidly which the torpedo senses and the motor starts.

The principles for both the missile and torpedo are the same.  Well, there are limitations on the depth you launch a missile but there’s certainly nothing difficult about it.

Mike

Quote from: sceptimatic on January 04, 2019, 07:39:06 AM

Quote from: MicroBeta on January 04, 2019, 07:17:54 AM

It boggles the mind that you believe the engine exhaust exerts zero force on the rocket...boggles the fuckin’ mind.

It’s only ridiculous to you because you don’t know what you’re talking about.  It’s not just burning rocket fuel.    If want you want to know why, look up venturies and nozzles for yourself because I’m tired of explaining shit to people who blindly dismiss what they don’t understand and have never tested.



IIUC, here's a synopsis of your premise of how denpressure effects vertical acceleration of a rocket.

- The density of the atmosphere (molecule stacking or however you define it) decreases with altitude.
- The force required for a rocket to ascend through the less dense atmosphere decreases but there is also a corresponding decrease of the reaction force due to thrust on the same less dense atmosphere.
- Therefore, the constant thrust, decreasing mass, and change in density during vertical ascent are always balanced so acceleration is exactly zero.

There are a few major problems with this reasoning.  The claim that a rocket can't accelerate must be subject to the following:

1. The effects of density versus altitude must be quantified.   
2. Variables within the system must be accounted for:
    a. The magnitude of thrust can vary from rocket to rocket.
    b. e.g. Two identical model rockets can have engines with identical size and weight but different thrust values.
    c. The rate at which fuel, and thus the corresponding decrease in mass, varies from engine to engine.
    d. Atmospheric pressure and density versus altitude is not linear.
    e. In taller rockets the density the rocket is pushing into and against may not be equal.
    f. Thrust to weight ratio varies from rocket to rocket

In summary:

1. The effect of denpressure vs altitude is not quantified.
2. The change in density of the atmosphere vs altitude is non-linear.
3. The magnitude of thrust and thrust to weight ratio varies between rockets.
4. The rate of change of the mass varies between rockets.

Working entirely within the denpressure model and considering the variables outlined above, at a minimum the following outcomes are possible:

1. If the magnitude of thrust and fuel consumption are balanced by the change in atmospheric density, it is possible for a rocket to have zero acceleration during vertical ascent.


2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

If we take all the variables into account and working within denpressure, it is possible to have zero vertical acceleration or a constant/variable vertical acceleration throughout ascent.  And, if I’m honest about it, these variables also imply that at some point in its ascent it should be possible for density to overcome thrust/fuel consumption and the rocket will decelerate (negative or downward acceleration) to the point where the rocket reaches equilibrium and not climb or fall until thrust is cutoff or increased.

Tthe point is that without quantifying denpressure and accounting for the variables between rockets, you can’t definitively say what the effect on the vertical acceleration will be.  A zero, a positive, or a negative acceleration should all be possible but there’s no way to know.

Mike

At least you're taking notice. I commend you for that.
Just one thing thought and it is nit picking but I feel I must do it. It this piece what you said: 2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Quoted to preserve the stupidity.

A Bugatti Chiron does 0-60 in 2.5 seconds. Do you think it does 200 to 260 in 2.5 seconds?
No. Decreaseing acceleration.

Ho Lee Fuk

That's Scepti for you.

Claims a rate of change cannot be constant.
Claims acceleration can not be reduced.
Now claims a propeller and rocket engine work on the same principles

And still claims to understand science?

Quote from: sceptimatic on January 04, 2019, 07:58:23 AM

Quote from: sokarul on January 04, 2019, 07:46:19 AM

Quote from: sceptimatic on January 04, 2019, 07:39:06 AM

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Quoted to preserve the stupidity.

A Bugatti Chiron does 0-60 in 2.5 seconds. Do you think it does 200 to 260 in 2.5 seconds?
No. Decreaseing acceleration.

Ho Lee Fuk

0-60 in 2.5 seconds is acceleration.

200 to 260 in 2.5 seconds is acceleration.

What's your issue?

He's pointing out that is decreasing acceleration.

There is no decreasing acceleration in what he points out.
In both cases it's acceleration.

10m/s² to 5m/s² is decreasing acceleration.

Quote from: sceptimatic on January 04, 2019, 07:28:37 AM

<snip>
However, I'd still love to know how a supposed ballistic missile of supposed 20 odd feet length can be pushed from deep water (100 feet or so) by compressed air to actually leap from it, clear by a few feet and then ignite and thrust to its target.

We seem to be drifting away from this.

It is a very simple process so I do not understand what your problem is.  There’s nothing technically complicated about it.  AAMOF, getting the thing airborne was one of more trivial engineering aspects of launching a missile.  The tough part was figuring out how to get it to its target.

High pressure gas is rapidly applied to the stern of the missile and it is impulse out of the tube.  Just like a dart from a blowgun.

Mike

Tell me something.
How do they manage to pressurise the arse end of the missile whilst leaving the rest of the tube and missile unpressurised, except for ambient atmospheric pressure and yet this is up against the might of the depth the sub is at under the ocean.

Can you explain how that works?

Quote from: MicroBeta on January 04, 2019, 07:17:54 AM

It boggles the mind that you believe the engine exhaust exerts zero force on the rocket...boggles the fuckin’ mind.

It’s only ridiculous to you because you don’t know what you’re talking about.  It’s not just burning rocket fuel.    If want you want to know why, look up venturies and nozzles for yourself because I’m tired of explaining shit to people who blindly dismiss what they don’t understand and have never tested.



IIUC, here's a synopsis of your premise of how denpressure effects vertical acceleration of a rocket.

- The density of the atmosphere (molecule stacking or however you define it) decreases with altitude.
- The force required for a rocket to ascend through the less dense atmosphere decreases but there is also a corresponding decrease of the reaction force due to thrust on the same less dense atmosphere.
- Therefore, the constant thrust, decreasing mass, and change in density during vertical ascent are always balanced so acceleration is exactly zero.

There are a few major problems with this reasoning.  The claim that a rocket can't accelerate must be subject to the following:

1. The effects of density versus altitude must be quantified.   
2. Variables within the system must be accounted for:
    a. The magnitude of thrust can vary from rocket to rocket.
    b. e.g. Two identical model rockets can have engines with identical size and weight but different thrust values.
    c. The rate at which fuel, and thus the corresponding decrease in mass, varies from engine to engine.
    d. Atmospheric pressure and density versus altitude is not linear.
    e. In taller rockets the density the rocket is pushing into and against may not be equal.
    f. Thrust to weight ratio varies from rocket to rocket

In summary:

1. The effect of denpressure vs altitude is not quantified.
2. The change in density of the atmosphere vs altitude is non-linear.
3. The magnitude of thrust and thrust to weight ratio varies between rockets.
4. The rate of change of the mass varies between rockets.

Working entirely within the denpressure model and considering the variables outlined above, at a minimum the following outcomes are possible:

1. If the magnitude of thrust and fuel consumption are balanced by the change in atmospheric density, it is possible for a rocket to have zero acceleration during vertical ascent.


2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

If we take all the variables into account and working within denpressure, it is possible to have zero vertical acceleration or a constant/variable vertical acceleration throughout ascent.  And, if I’m honest about it, these variables also imply that at some point in its ascent it should be possible for density to overcome thrust/fuel consumption and the rocket will decelerate (negative or downward acceleration) to the point where the rocket reaches equilibrium and not climb or fall until thrust is cutoff or increased.

Tthe point is that without quantifying denpressure and accounting for the variables between rockets, you can’t definitively say what the effect on the vertical acceleration will be.  A zero, a positive, or a negative acceleration should all be possible but there’s no way to know.

Mike

At least you're taking notice. I commend you for that.
Just one thing though and it is nit picking but I feel I must do it. It this piece what you said: 2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Oh dear God.  SMH

From an engineering standpoint acceleration is always a vector quantity.  Whether it’s a positive or negative number it is merely acceleration.  The sign of value tells me the vector direction in relation to the system.  So, since I’m an engineer, I don’t use layman’s terms like decelerate because it has no meaning.  It is either a positive or negative value that can be increasing or decreasing.

I realize I mixed up my terms with all the cutting and pasting and editing.  I do that sometimes when trying to tailor a discussion for non-engineers.  I apologize if I confused you.  From now on I’ll stick to the standard engineering convention.

With that said, you didn’t comment about the inconsistencies I pointed out in you assertions about the acceleration of rockets.

Mike

10m/s² to 5m/s² is decreasing acceleration.

No it's not. It's simply altering acceleration at different speeds.

Quote from: sceptimatic on January 04, 2019, 07:39:06 AM

Quote from: MicroBeta on January 04, 2019, 07:17:54 AM

It boggles the mind that you believe the engine exhaust exerts zero force on the rocket...boggles the fuckin’ mind.

It’s only ridiculous to you because you don’t know what you’re talking about.  It’s not just burning rocket fuel.    If want you want to know why, look up venturies and nozzles for yourself because I’m tired of explaining shit to people who blindly dismiss what they don’t understand and have never tested.



IIUC, here's a synopsis of your premise of how denpressure effects vertical acceleration of a rocket.

- The density of the atmosphere (molecule stacking or however you define it) decreases with altitude.
- The force required for a rocket to ascend through the less dense atmosphere decreases but there is also a corresponding decrease of the reaction force due to thrust on the same less dense atmosphere.
- Therefore, the constant thrust, decreasing mass, and change in density during vertical ascent are always balanced so acceleration is exactly zero.

There are a few major problems with this reasoning.  The claim that a rocket can't accelerate must be subject to the following:

1. The effects of density versus altitude must be quantified.   
2. Variables within the system must be accounted for:
    a. The magnitude of thrust can vary from rocket to rocket.
    b. e.g. Two identical model rockets can have engines with identical size and weight but different thrust values.
    c. The rate at which fuel, and thus the corresponding decrease in mass, varies from engine to engine.
    d. Atmospheric pressure and density versus altitude is not linear.
    e. In taller rockets the density the rocket is pushing into and against may not be equal.
    f. Thrust to weight ratio varies from rocket to rocket

In summary:

1. The effect of denpressure vs altitude is not quantified.
2. The change in density of the atmosphere vs altitude is non-linear.
3. The magnitude of thrust and thrust to weight ratio varies between rockets.
4. The rate of change of the mass varies between rockets.

Working entirely within the denpressure model and considering the variables outlined above, at a minimum the following outcomes are possible:

1. If the magnitude of thrust and fuel consumption are balanced by the change in atmospheric density, it is possible for a rocket to have zero acceleration during vertical ascent.


2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

If we take all the variables into account and working within denpressure, it is possible to have zero vertical acceleration or a constant/variable vertical acceleration throughout ascent.  And, if I’m honest about it, these variables also imply that at some point in its ascent it should be possible for density to overcome thrust/fuel consumption and the rocket will decelerate (negative or downward acceleration) to the point where the rocket reaches equilibrium and not climb or fall until thrust is cutoff or increased.

Tthe point is that without quantifying denpressure and accounting for the variables between rockets, you can’t definitively say what the effect on the vertical acceleration will be.  A zero, a positive, or a negative acceleration should all be possible but there’s no way to know.

Mike

At least you're taking notice. I commend you for that.
Just one thing though and it is nit picking but I feel I must do it. It this piece what you said: 2. If the magnitude of thrust and fuel consumption are not balanced by the change in atmospheric density is possible for a rocket to have a constant or a decreasing acceleration during ascent.

You can't have a decreasing acceleration. You can have a decreasing speed.

Just nitpicking that's all and nothing more.

Oh dear God.  SMH

From an engineering standpoint acceleration is always a vector quantity.  Whether it’s a positive or negative number it is merely acceleration.  The sign of value tells me the vector direction in relation to the system.  So, since I’m an engineer, I don’t use layman’s terms like decelerate because it has no meaning.  It is either a positive or negative value that can be increasing or decreasing.

I realize I mixed up my terms with all the cutting and pasting and editing.  I do that sometimes when trying to tailor a discussion for non-engineers.  I apologize if I confused you.  From now on I’ll stick to the standard engineering convention.

With that said, you didn’t comment about the inconsistencies I pointed out in you assertions about the acceleration of rockets.

Mike

I forgive you. Now what specific thing have I not answered?

Quote from: sokarul on January 04, 2019, 08:25:26 AM

10m/s² to 5m/s² is decreasing acceleration.

No it's not. It's simply altering acceleration at different speeds.

oh man this guy is definitely not good with numbers.



Skip to 1:40 for INCREASING velocity due to an INCREASING acell because the INCREASE in angle of coaster. whih is all still positive

Then at 1:45 uphill you have DECREASING velocity due to DECREASING accelleration due to leveling off of coaster but all still Postive forward motion as noted, theyre still.moving forward.

Quote from: MicroBeta on January 04, 2019, 08:04:02 AM

Quote from: sceptimatic on January 04, 2019, 07:28:37 AM

<snip>
However, I'd still love to know how a supposed ballistic missile of supposed 20 odd feet length can be pushed from deep water (100 feet or so) by compressed air to actually leap from it, clear by a few feet and then ignite and thrust to its target.

We seem to be drifting away from this.

It is a very simple process so I do not understand what your problem is.  There’s nothing technically complicated about it.  AAMOF, getting the thing airborne was one of more trivial engineering aspects of launching a missile.  The tough part was figuring out how to get it to its target.

High pressure gas is rapidly applied to the stern of the missile and it is impulse out of the tube.  Just like a dart from a blowgun.

Mike

Tell me something.
How do they manage to pressurise the arse end of the missile whilst leaving the rest of the tube and missile unpressurised, except for ambient atmospheric pressure and yet this is up against the might of the depth the sub is at under the ocean.

Can you explain how that works?

You don’t.  I said “High pressure gas is rapidly applied to the stern of the missile and it is impulse out of the tube.  Just like a dart from a blowgun.”

An air powered bb or pellet gun work the same way.  The bb doesn’t have a pressure tight seal between it and the chamber of the gun so if you slowly increased pressure behind the bb it would never leave the barrel because the air would just leak around the bb to the lower pressure area.  However, if you rapidly apply pressure behind the bb it will build up much, much faster than it could leak past the bb and it will be impulsed out of the barrel.

A torpedo and missile work exactly the same way.  I don’t know why you’re so hung up on what is actually the easiest part of launching a missile from a submarine.

Mike