Hyperloop Bankrupt and Busted.

[Uttamattamakin]

8 hours ago, leadeater said:

Carbon Fibre was literally never considered viable for space usage, wonder material sure, space age attributed no. It's the same reason only one person/company ever tried to use carbon fibre the way they did and died and took the lives of others while doing it.

I felt lazy so I asked Microsoft Co Pilot.  I'd add to this Space Ship 1 and Space Ship2 designed by Scaled Composites. 

8 hours ago, leadeater said:

Actual engineers don't listen to Nat Geographic etc and treat materials as wonderous things perfect for everything, that is not a thing. Only those that ignore common sense do, they die while doing it.

 

As you may have noticed Virgin used Metal not Carbon Fibre for the tubes, they had common sense, it was never even considered.

See above 

 

8 hours ago, leadeater said:

Why abandon a strong vacuum? What is a strong vacuum?

Strong enough to crush a metal tube if the tube isn't made right.  

For our purposes a weak vacuum is anything less than 1 ATM of pressure and up to say the air pressure at 10,000 feet.  Air planes that are not pressurized can fly for hours at that height with no hypoxia effecting the passengers or crew without supplemental oxygen. 

8 hours ago, leadeater said:

 

If ThrustSSC were operating in 0.5atm how much thrust(hp) would it have needed? How much at 0.25atm?

If we make the simplest non-linear model and approximate the drag-pressure dependence as quadratic.  

For a constant velocity

Drag ~ pressure^2

 

So, Doubling the pressure would be 4 times the drag while 1/2in'g the pressure would be 1/4 the drag.  The thrust would be equal in magnitude but opposite in direction to the drag.   Here is a simple plot screen shot from my own desktop. 

 

So we see from here that at 0.5 Atm for a constant velocity of mach1  the drag force is about 25% of what it would be at 1 ATM at sea level.  So, 2500 hp.   
For a typical high speed train going about 0.25 of the speed of sound the green line on that chart applies.  At 1/2 of at atm a train going  around 300 km/h would encounter 0.066, or 6% of the drag force at 1 ATM.   (When discussing how much of a mag lev would be needed in such a system this needs to be taken account of). 

What I propose would not be 1/2 of an atmosphere but instead to operate at the pressure of 10,00 feet.  Which is 0.7 atm.  People who do not have breathing problems can breathe for hours at this level of pressure.   This is the altitude a jet will dive to if it experiences decompression at cruising altitude. 

 

At 0.7 ATM pressure a train maintaining 1/2 the speed of sound would need only about 30% of the thrust it would need at 1 atmosphere. 

 

8 hours ago, leadeater said:

At some point it is actually more viable, more cost effective and more reliable to just put the train in low pressure than to throw the equivalent amounts of energy at the situation as a contained large explosive bomb continuously.

Agreed see above.  Lower pressure but not so low that it causes problems like catastrophic implosion. 

 

8 hours ago, leadeater said:

In principle Hyperloop is exactly this, looking to optimize every factor to achieve the peak possible at the lowest practical effort for each factor. There are just a lot of things we don't do that is needed in a hyperloop that make it expensive or not fully understood. Do consider that if you never do it then you'll never understand it and you'll also never create the knowledge, tooling and supply chain to make it cheaper and thus commercially viable.

What what cost do you want to go a bit faster? 

 

8 hours ago, leadeater said:

Space flight was always said to not be commercially viable and nation state only, now we have multiple different companies in different countries all achieving what was said to not be "commercially viable".

Until now the issue wasn't could a private company make money but could anyone but the government afford the bill. 

The truth is space has BOTH Always been a private enterprise AND always will be government funded via contracts.   All sorts of private entities were involved with the Space Shuttle.  Just now we have Space X putting their name right on it and using it to service contracts that are also not government. 

 

Before I go on one thing has to be said.  

 

You're telling me the person who has actually dedicated their professional life to space exploration all of that.  I know that. 

 

I know you mean well but in response to your sermon I need to remind you I am in the choir.  Though you are preaching I probably know the scriptures of nature, the laws of nature better. 

 

Do you all see (Don't you remove this image lots of people here have tried to talk down to or about me.  NOw that this is serious lets be serious.  One of the people on this thread knows all of these factors and can work them out in their head.  I can be wrong but I admit it, correct it, and have NEVER INSULTED ANYONE HERE. Yet I get preached to and insulted all the time

 

@leadeater I am not distinctly speaking about you on this but just something that has  been building up for a while.   You have been civil and wonderful and a real role model in this thread.  

So I give you a curtsy 

 

A general thing I need to get off my chest. 

 

I am a bit lost I am told the news section is super serious by someone else.  Then I should be able to post my CV and credentials and all the dilettantes should be silent.  Since what I say is based on knowledge too deep to lay all of it down here.  I should not have to justify a thing. There are calculations in my head behind every word that would take a semester course to explain.

 

They are how I knew that LK99 was 99.9% BS.  Remember how soooo many here were telling me I didn't or couldn't know about it.  Accused me of making up that I know what I'm talking about.  Did any one of those people have the integrity to say you know what... we were wrong.  No instead they try to act like specialists in this area of knowledge couldn't tell how unlikely it was to be right after viewing the data. 

 

 I don't think that this is all so serious, so I don't think that way.  I think that some degree of banter and fun are part of this.   Anyone can know things and anyone can make a good point.  Just don't forget at least one of us has dedicated their life to science.  Not just taken a course in it or something.  If this is serious then Professor Uttamattamakin is in class.  If not then I am here to have fun.  

 

Now I don't want to hear anyone try to come back at this about things they looked up on the internet (which I already knew and knew why they don't apply or don't apply the way they think they do.  If you want to talk down to me show me your PhD.   If some of you who I won't name did know what you are doing then you'd know that you are ... not even wrong.    Not right but so far off that youd need to learn more in order to be wrong. 

 

Now I  have a physics textbook to help edit.   I can relax by solving some equations.  Jeeze I try to relax and kick around some ideas and this is what I get.  Now I'm off wearing a suit. 

 

I feel my boy Thunderf00t and why he started his video with a clip of (was that from the Highlander) sharpening his sword to take no prisoners.)

Darn boring textbook... So I looked up carbon fiber and hyperloop.  One of those outfits really did develop a "wonder matterial" with Carbon fiber and called it Vibrainium. LOL. 

https://medium.com/@matmatch/which-materials-are-making-the-hyperloop-possible-393c96189602#:~:text=In the development of its Hyperloop pods%2C HTT,skin type material to protect the Hyperloop pods.

 

Quote

In the development of its Hyperloop pods, HTT has developed a new type of carbon fibre composite that is eight times stronger than aluminium and ten times stronger than steel alternatives. The material, named vibranium (inspired by Marvel’s fictional metal), has been designed to be a skin type material to protect the Hyperloop pods.

I can just hear Thunderf00ts voice in my head reading that part. LMBO

[wanderingfool2]

7 hours ago, leadeater said:

Carbon Fibre was literally never considered viable for space usage, wonder material sure, space age attributed no. It's the same reason only one person/company ever tried to use carbon fibre the way they did and died and took the lives of others while doing it.

 

Actual engineers don't listen to Nat Geographic etc and treat materials as wonderous things perfect for everything, that is not a thing. Only those that ignore common sense do, they die while doing it.

 

As you may have noticed Virgin used Metal not Carbon Fibre for the tubes, they had common sense, it was never even considered.

I do agree in that it probably was never considered viable; although they might have still tried running the numbers to see if it might be viable...then again carbon fiber's drawback would be changing pressure the material just doesn't hold up overtime.

 

A note about space usage though, firefly Alpha actually uses a carbon fibre composite for their framework on their rocket (but those rockets are one time use things).

I think the Electron rocket also is carbon fibre.  SpaceX actually considered carbon fibre for their starship, although they eventually switched to steel after realizing steel had better strength across all temperature ranges that it would experience.

 

6 minutes ago, Uttamattamakin said:

I can be wrong but I admit it, correct it, and have NEVER INSULTED ANYONE HERE. Yet I get preached to and insulted all the time

Your ideas you present are being attacked; and your overall insistence on relying on those facts...and yes generally your ideas are attacked because you are attributing the ideas as facts because you overall argue in bad faith.

 

It's like the whole insistence on using 10m as a round number, when clearly the number should be 3.3m.  The claim that people like ThunderF00t knows what he's talking about and has degrees in it when in fact his degree is in Chemistry.

 

10 minutes ago, Uttamattamakin said:

If we make the simplest non-linear model and approximate the drag-pressure dependence as quadratic.  

For a constant velocity

Drag ~ pressure^2

Show an actual formula then that shows Drag ~ pressure squared...because as I've pointed out already twice the formula CLEARLY shows pressure (density) in the formula has a LINEAR effect on drag.

 

Here's the formula that I've been using, that you claim I should also be using (thinking I used the wrong formula).

dragforce = -1/2 * C * p * A * v2

C = drag co-efficient

p = density

A = cross-section area

v = velocity.

 

As you stated constant velocity, so v is no longer a variable in the equation but a fixed number.  A and C will also be fixed number in this case

v² since v is constant you can express v²  as some constant as well (so you can combine -1/2, A, C and v² into a single constant)

 

It's basic level math at this point, dragforce = B * p

Where B is some fixed constant that is determined by B = -1/2 * A * C * v2.  The key is B should not be changing..so with a relatively constant B the pressure can be said to have a linear effect.

 

Now if you really wanted to go into detail, you could talk about how the drag co-efficient also is a function of density, but from what I've seen it contributes to a smaller effect; as can be seen again in the boxy version vs M3 version, the ratios stay the same (they don't grow exponentially apart when you factor out the velocity)

 

38 minutes ago, Uttamattamakin said:

I am a bit lost I am told the news section is super serious by someone else.  Then I should be able to post my CV and credentials and all the dilettantes should be silent.  Since what I say is based on knowledge too deep to lay all of it down here.  I should not have to justify a thing. There are calculations in my head behind every word that would take a semester course to explain. They are how I knew that LK99 was 99.9% BS. 

 

 I don't think that this is all so serious, so I don't think that way.  I think that some degree of banter and fun are part of this.   Anyone can know things and anyone can make a good point.  Just don't forget at least one of us has dedicated their life to science.  Not just taken a course in it or something.  If this is serious then Professor Uttamattamakin is in class.  If not then I am here to have fun.  

The issue is you are making outlandish assumptions, like a 10m wide tunnel

 

I don't care if you have a PhD in mathematics/physics etc...if you make an outlandish claim based on assumptions that are faulty then your numbers come out wrong.  It's the same argument being made over on the SpaceX stuff, you make faulty statements based on terrible assumptions and claim to know better when you get called out on it.

 

The fact is:

No the tunnel won't be 10m wide, and won't be 10 cm thick

No you cannot just simply improve the aerodynamics of modern trains

No the density of air doesn't contribute to a square of density.

 

Quadruple the density of air and you now are only afford half the speed to maintain the same drag.

 

Again, PhD's can mean nothing because again I know computer science PhD who cannot properly operate a standard computer.  A PhD does not prevent you from making an ignorant or blatantly wrong statement...it is concerning though that you seem to resort to the whole I have a PhD when your arguments get picked apart.

 

I dare you to go to one of your colleagues, and show them the drag formula from NASA or the edu one, and then tell them that changing p by half will result in drag being 1/4 the size.

 

 

Anyways, one of the things I wanted to point out.

 

LIGO

https://www.ligo.caltech.edu/page/vacuum

1.2m tube - drum roll please, thickness of 3mm (at an ultra high vacuum).  Even using the rule of thumb before it would state you need 1.2cm.  So clearly at 2m, using 2cm would be overkill.

 

[Uttamattamakin]

58 minutes ago, HenrySalayne said:

The tube is clearly not infinitely long and they added frames / stiffeners to prevent it from buckling and collapsing! Unfair!

Not to mention they used it for 20 years and clearly didn't use stainless steel (since there is a lot of rust). Fascinating, but also against the rules...

 

I think that shows a mentality I can absolutely not agree with...

I don't either which is why I never decided to post my CV until now.  I also said that ANYONE can make a good point and ANYONE can be wrong.  I've admitted if I was wrong about something many times.   

 

I also never denigrated anyone when explaining to them WHY they are wrong.  

 

Can you and @wanderingfool2 say the same regarding how you write to me much of the time?.  Honestly? 

 

In speaking of which Wandering fool.  Do you want a full course on Fluid dynamics?   OR do you want a formula that is good enough for a quick estimate?    A course taught by me cost the state of IL 1242 USD / Contact hour.  For free you get a simple estimation based on what I know of things. 

 

Here's a short explanation for where you are going wrong with the application of that source to this.  I know what LIGO is doing very well.  I am working on a Space Based successor to it called LISA.   Building a relatively small tube down which to send light is one thing.  Building a tube real human beings who come in all shapes and sizes and some of whom are like my father, blind, with COPD and sometimes need to be moved in a Wheel chair.  

Any system that can only be ridden by svelte toned young people who are able to climb over and around and all of that is not worth the money.  The tunnel size comes from scaling up the Hyperloop 1 tunnel to carry a passenger pot that would meet the same standards as applied to a passenger train in the United States of America. 

IT's also odd that you would object to that formula.  Since it shows that as you remove pressure from the tube you get a HUGE return in having less drag.  Thereby needing less thrust, and being able to go faster while using less energy.  If anything, my formula demonstrates in simple terms WHY hyperloop is attractive.  Lowering the pressure in the tube even a little bit makes it much more efficient. f

 

We can talk about different pressures, materials, thermal considerations and on and on.  We can even collectively build a computer model if you like.  Just remember KEEP IT FUN.  KEEP IT LIGHT.  Don't be so serious.  I'd not be surprised if this message board could work out an actual practical Hyperloop or hyperloop like (Hyperloop lite???) system better than a billion dollar company.   

Said with a smile. 
 

[wanderingfool2]

46 minutes ago, Uttamattamakin said:

Here's a short explanation for where you are going wrong with the application of that source to this.  I know what LIGO is doing very well.  I am working on a Space Based successor to it called LISA.   Building a relatively small tube down which to send light is one thing.  Building a tube real human beings who come in all shapes and sizes and some of whom are like my father, blind, with COPD and sometimes need to be moved in a Wheel chair.  

Any system that can only be ridden by svelte toned young people who are able to climb over and around and all of that is not worth the money.  The tunnel size comes from scaling up the Hyperloop 1 tunnel to carry a passenger pot that would meet the same standards as applied to a passenger train in the United States of America. 

And this is exactly why I said earlier people who rely on things like a PhD's mean nothing; because you are lacking the adequate capacity to apply basic level logic/reasoning when your ideas are challenged.  (It's like I said about ThunderF00t's videos, he pulls numbers out of what amounts to thin air that matches his argument and pretends they are the be all and end all).

 

Otherwise you would have noticed that I already pointed out that Canada Line as an example has trains could fit in a but that's less than 4 meters (the actual one they use is 5 meters, but again we are talking about a system when when at capacity is sitting 4 people across it and two people standing next to the seat which is overkill) .

 

The London Underground only has tunnels 3.56 meters.  To suggest a hyperloop would require more is just crazy.

 

I brought up LIGO because it shows that the 1/100 rule does take liberties in terms of how much extra safety factor might be involved...so 2cm for 2m is completely a reasonable amount (if not an excessive amount, as it won't be an ultra strong vacuum).  Ligo gets away with using 1/400.  Not denying that there wouldn't be extra bits of safety factor when humans are involved, but we also aren't talking about ultra strong vacuums.

 

As a few facts as well, talking about safety; Via Rail had passengers stuck for 18 hours.  Canada Line has broken down a few times now and in some cases it took 3 hours before the people could "safely" exit the train.

 

1 hour ago, Uttamattamakin said:

IT's also odd that you would object to that formula.  Since it shows that as you remove pressure from the tube you get a HUGE return in having less drag.  Thereby needing less thrust, and being able to go faster while using less energy.  If anything, my formula demonstrates in simple terms WHY hyperloop is attractive.  Lowering the pressure in the tube even a little bit makes it much more efficient. f

Reading comprehension by you is at 0 at the moment.

 

Where did I object to using that formula?  I object to you with your fancy Masters in supposedly this field lacking the basic understanding of a formula.  Yes, if you plot a curve based on velocity it has a non-linear trajectory...but you seem to fail that if you plot the curve based on density, or based on drag co-efficient then you get *gasps* a line

 

 

You essentially said going from 1 atm to 0.5 atm means drag is about 25% assuming constant velocity...which is nonsense because the equation clearly states it will be 50%.  Again the only variable that changes drag non-linearly in that equation is velocity; which you set as a fixed velocity.

17 hours ago, Uttamattamakin said:

Don't believe me, look at this graph again since you seemed to think it disproved me.

 

Look at when we assume velocity V = 40 and V = 60 (since we assume constant velocity, it should only require 1 but lets do 2 to verify it's in the ballpark)

Look at when we assume velocity V = 60

The standard nose (~0.5 drag co-efficient as defined in the paper)

Drag(N) = ~4700 @ V = 40

Drag(N) = ~10500@ V = 60

 

Sharp Nose (~0.26 drag co-efficient as defined)

Drag(N) = ~2200 @ V = 40

Drag(N) = ~5600 @ V = 60

 

Notice, the only thing that has changed is the drag co-efficient in this example.

Lets divide the drag force from each type to get a ratio.  If it's linear it should roughly match (tolerances of me eyeballing the data since it didn't give it in a table form so probably ~200+- in the guess), if it's non-linear there should be a difference.  Still enough to check, as your claim of things being square should show a drastic difference at half the drag co-efficient.  Remember the predicted should be roughly ~0.52 as per my assertion that the variable contributes to the equation linearly; if your assertion of square terms it should equate to a ratio of ~0.27

 

So lets see the ratio

5600 / 10500 = ~0.53

2200 / 4700 = ~0.47

 

I don't need a masters in order to see that a paper, which was written by multiple PhD's, with experimental data and calculated data is validating my point that drag co-efficient and changing the atm will have similar effects that are linear.

 

 

And not that it matters, my education is a Bachelors in Applied Sciences (Computer science), graduated with honors; in the arrangements of courses I took "top level courses" that actually could be also applied to beginner level masters in mathematics (not joking, there were actually Math majors who were in their Masters program)...and specifically as well if I wanted to I could have taken 1 extra course and gotten a dual bachelors degree in both Applied Sciences AND a bachelors in mathematics, but I didn't want to waste money/time on what amounts to essentially a paperweight.  Some of the literal classes I took literally had the description linear equations, discrete mathematics, etc.

 

1 hour ago, Uttamattamakin said:

In speaking of which Wandering fool.  Do you want a full course on Fluid dynamics?   OR do you want a formula that is good enough for a quick estimate?    A course taught by me cost the state of IL 1242 USD / Contact hour.  For free you get a simple estimation based on what I know of things. 

So far what has been presented has only shown proof towards what I have been stating.

 

Changing atm has a linear effect (reducing it by half, and drag decreases by half).  Reduce aerodynamic by half you reduce drag by half.

Reduce both atm and aerodynamic by half, you can now double your v and get the same drag.

 

If you think the following formula is wrong, then state what you think is wrong

dragforce = -1/2 * C * p * A * v²

C = drag co-efficient

p = density

A = cross-section area

v = velocity.

 

But at the moment it's you stating it density p is a square; which is abhorently wrong given the above formula.  The only other reasoning is to state the one of the other variables C, or A has an equation that also has p in it...but as per the NASA site, and the other papers I linked they all pretty much assume the drag co-efficient is a constant for a given design.

 

The way you are stating it, it's like you are thinking the formula is like the following

dragforce = -1/2 * (C * p * A * v)²

[leadeater]

4 hours ago, wanderingfool2 said:

A note about space usage though, firefly Alpha actually uses a carbon fibre composite for their framework on their rocket (but those rockets are one time use things).

I think the Electron rocket also is carbon fibre.  SpaceX actually considered carbon fibre for their starship, although they eventually switched to steel after realizing steel had better strength across all temperature ranges that it would experience.

Oh yes I know it is used, I was commenting on when Cabron Fibre was developed and became the new hottness, NASA determined it was not suitable. It took a long ass time of perfecting usage of it to get it in applications we have it today.

[leadeater]

5 hours ago, Uttamattamakin said:

I felt lazy so I asked Microsoft Co Pilot.  I'd add to this Space Ship 1 and Space Ship2 designed by Scaled Composites. 

Sure but how many rockets and usages between earth atmosphere to space 

 

I mean yea my comment was inaccurate but Carbon Fibre until SpaceX was never used as a structural material for space travel, going to space.

 

5 hours ago, Uttamattamakin said:

Strong enough to crush a metal tube if the tube isn't made right.  

Then make it right, literally not an issue at all which is what you have been arguing this whole time. The start and end of it is we know how and can make metal tubes do this job just fine. Literally argue about other aspects and not this, this is NOT a problem in the slightest.

 

At least if you want to go on about this in particular focus on cost.

[Uttamattamakin]

59 minutes ago, wanderingfool2 said:

If you think the following formula is wrong, then state what you think is wrong

dragforce = -1/2 * C * p * A * v²

C = drag co-efficient

p = density

A = cross-section area

v = velocity.

Leadeater and I were talking about a relationship between 

 

PRESSURE and Drag force not DENSITY and drag force.    

 

Lets take the equation you have up there.  Pressure is force / Area.  So we could derive a ... drag pressure 

 

Drag force / A = 1/2 * C * p * v²

 

But it's more complicated because p density also depends on pressure.     Consider the ideal gas law, and assume the atmosphere in low pressure is ideal enough to apply it.   

 

PV=NRT.  (N is the number of particles usualy involves avogadros number some versions just use m, R is the ideal gas constant)  Solve for N/V to get a sort of  molecular density.    N/V=P/RT  Putting these together we get. 

Drag force / A =1/2 * C * (N/V) * v²=  1/2 * C * (P/RT) * v²

An equation that has the same, or the same sort of variable on both sides tend to become very non linear and very complicated very fast.  SO instead of doing all of that for a forum post... I just said lets assume it's just a bit more than linear.  

 

Plus it matches the observation that the higher a plane flies, the lower the air pressure, the less fuel is used to maintain velocity. 

59 minutes ago, wanderingfool2 said:

But at the moment it's you stating it density p is a square; which is abhorently wrong given the above formula.  

 

The way you are stating it, it's like you are thinking the formula is like the following

dragforce = -1/2 * (C * p * A * v)²

See... you are squareing the p there which is not pressure it is density.   

 

@Wanderingfool2  Id' take it personally if you weren't like this very often.  You hurl all manner of insults but you don't seem to get the equation you just wrote. 

 

7 minutes ago, leadeater said:

Sure but how many rockets and usages between earth atmosphere to space 

Lol.  Yeah.    Then it comes back to what we both (I think both) tried to explain to folks about a Balloon holding IN pressure VS a chamber holding OUT pressure.  Very different things once one realizes Carbon fiber just makes very rigid balloons. 

 

7 minutes ago, leadeater said:

At least if you want to go on about this in particular focus on cost.

 Eh I'm kinda over it.  I figure if anyone can do this it will be Saudi Arabia which has money independent of spending it wisely OR the PRC which is the worlds factory and can just make things happen by government force alone.   

 

 

[leadeater]

5 hours ago, Uttamattamakin said:

The truth is space has BOTH Always been a private enterprise AND always will be government funded via contracts.   All sorts of private entities were involved with the Space Shuttle.  Just now we have Space X putting their name right on it and using it to service contracts that are also not government. 

 

If it's government funded then it's natation state. Who does the work doesn't matter, it's not like USA Gov builds F35, B21 etc do they?

 

Where as Rocket Labs in my own country is not majority government funded aka not nation state

[Uttamattamakin]

3 minutes ago, leadeater said:

If it's government funded then it's natation state. Who does the work doesn't matter, it's not like USA Gov builds F35, B21 etc do they?

 

Where as Rocket Labs in my own country is not majority government funded aka not nation state

Yeah here in the states we have a way of thinking we are such a capitalist free enterprising country.   YET most companies that do things like Aerospace or tech or even FARMS are all subsidized by and depend on the government.   
 

I'll bet your rocket lab IS truly independent of government.  Meanwhile in the USA. 

[wanderingfool2]

29 minutes ago, Uttamattamakin said:

See... you are squareing the p there which is not pressure it is density.   

 

@Wanderingfool2  Id' take it personally if you weren't like this very often.  You hurl all manner of insults but you don't seem to get the equation you just wrote. 

I'm attacking your premises that show a complete lack of understanding, and your insistence that you are an expert in a field making you the authority.

 

If you notice, or even clued in I said that you seem to be under the belief the formula was like that...notice how I said you seem to think the formula is like that; while if you look above I specify the real formula.

 

Here's a quote of myself so you can see exactly how absurd you sound by somehow quoting as though implying that the one you quoted is the correct formula.

 

1 hour ago, wanderingfool2 said:

If you think the following formula is wrong, then state what you think is wrong

dragforce = -1/2 * C * p * A * v²

 

...

 

The way you are stating it, it's like you are thinking the formula is like the following

dragforce = -1/2 * (C * p * A * v)²

So yea, if you think the bolded formula is the correct formula then you are a lost cause.

 

35 minutes ago, Uttamattamakin said:

An equation that has the same, or the same sort of variable on both sides tend to become very non linear and very complicated very fast.  SO instead of doing all of that for a forum post... I just said lets assume it's just a bit more than linear.  

See the quoted below

6 hours ago, Uttamattamakin said:

If we make the simplest non-linear model and approximate the drag-pressure dependence as quadratic.  

For a constant velocity

Drag ~ pressure^2

6 hours ago, Uttamattamakin said:

So we see from here that at 0.5 Atm for a constant velocity of mach1  the drag force is about 25% of what it would be at 1 ATM at sea level.  So, 2500 hp.   
For a typical high speed train going about 0.25 of the speed of sound the green line on that chart applies.  At 1/2 of at atm a train going  around 300 km/h would encounter 0.066, or 6% of the drag force at 1 ATM.   (When discussing how much of a mag lev would be needed in such a system this needs to be taken account of). 

What I propose would not be 1/2 of an atmosphere but instead to operate at the pressure of 10,00 feet.  Which is 0.7 atm.  People who do not have breathing problems can breathe for hours at this level of pressure.   This is the altitude a jet will dive to if it experiences decompression at cruising altitude. 

Don't try to gaslight me.  You literally made made a linear system non-linear in your assumptions here and made some a crazy statement which is false.

 

ATM and density are linked linearly as well: https://www.omnicalculator.com/physics/air-density
1 ATM @ 32C with no moisture = 1.09232 kg/m3

0.5 ATM @ 32 C with no moisture = 0.54616 kg/m3

 

So back to what I've been saying changing p has a linear effect...you are talking about 1atm and 0.7 atm and mindlessly pulling that it's now somehow a quadratic effect to justify; when in reality you still are looking at a linear relation...unless you again can show a formula that is proving otherwise.

 

45 minutes ago, Uttamattamakin said:

Drag force / A =1/2 * C * (N/V) * v²=  1/2 * C * (P/RT) * v²

Notice how only the velocity term is squared in your equation.  You mentioned assume a constant velocity...which means you guess it...according to your formulate you can replace v^2 with a constant and there  you have it no more squared terms.

 

This is why I attack your facts because you are claiming to be an expert in a field and you make arguments like the above.  Either you truly don't understand the topic, or you are arguing in bad faith.

 

 

Here's some NASA documents for you:

https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/drageq.html

They are using the same formula that I have been using all along, and is our baseline
D = Cd * A * .5 * r * V^2 

Lets see how they define density

https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/density.html

Quote

we could define its density to be the mass divided by the volume

So yea, 1 atm vs 0.5atm you will have density in the equation to be effectively linear (It is technically associated with temperature humidity etc, but it still follows again a linear path).

 

 

Let me put it this way, you have 2 knobs one that changes "pressure" and one that changes "drag co-efficient".  You turn the pressure knob...what part of the formula makes you think that the drag will increase at a quadratic rate?

[suicidalfranco]

So of this thread just the inevitable bickering between a physicist and an engineer? Cause if so the only person missing is a mathematician and we can get a full circle

[Uttamattamakin]

2 hours ago, suicidalfranco said:

So of this thread just the inevitable bickering between a physicist and an engineer? Cause if so the only person missing is a mathematician and we can get a full circle

Basically. LMBO. 
 

@wanderingfool2  I have explained how and why you are so far off for trying to use simple linear models for an extreme engineering question like this.  There are equations that you see in the textbook in intro physics.  Then there are the ones that consider all the factors one sees in real life.  You know the kind that make it necssary to model complex systems with super computers.  

 

 

 

The fact that you are so wrong that the above quote applies all while making it about the whole idea that I know what I litterally teach to other people and have a degree in..    It reminds me of when I teach remedial math and theres one student who is CERTAIN they are right and that both I and the computer homework system that graded them are both wrong.    Then they get angry when I do the problem again and show them that they are wrong.  Thats. you. 

My final word on this.  

There are things which violate the laws of physics and they don't exist for that reason.  Like traveling faster than light (without perhaps warp drive). 

Then there are things like Hyperloop, Lk99 and perhaps room temp super conductors in general, and the 12VHPWR standard.  They PUSH the laws of physics, are very hard to make work for that reason, and if they work even a little at best you get Bubbling Plastic on your GPUs power connector. 

 

Time to relax

 

[wanderingfool2]

1 hour ago, Uttamattamakin said:

wanderingfool2  I have explained how and why you are so far off for trying to use simple linear models for an extreme engineering question like this.  There are equations that you see in the textbook in intro physics.  Then there are the ones that consider all the factors one sees in real life.  You know the kind that make it necssary to model complex systems with super computers.  

Then show the equations that show you are right over the "simple" equations that appear in PhD papers analyzing the facts.

 

You say that it's quadratic, then show the formula...not some stupid argument that since there is a square in the equation every variable becomes squared.

 

You are approaching it with the same mentality that the CCNA did when I asked about the security of their implementation saying it didn't look right and being assured I didn't know what I was talking about...until I finally had to do a POC to show that the system wasn't implemented the way their so called claim was. [And yes, they were going to my superiors saying I was wrong before I demonstrated my POC].

 

Again, if you think that formula is so wrong and that reducing ATM from 1 ATM to 0.5 results in a 4x drag reduction then show the formula; show the reference points.

 

When it appears on a NASA site, discussion around planes (and guess what planes are definitely in scope of the pressures I am talking about), and on papers discussing aerodynamics and energies involved in a train system, then it's up to you to state why the "basic" formula's don't hold up.

 

So far you are just doing a "trust me, it's my job"; and using frankly insane estimates; your "education" means squat if you don't provide the justification.

 

e.g.

Why do you proportional to drag ~ pressure^2, when the "basic" formulas all posted here are stating otherwise....your argument to that was posting a rant where the formula was again pressure changes meant a linear change.

 

I do recognize that if you accept pressure^2 would be better for hyperloop's viability, but I'm arguing against you because you are wrong or at least having shown any evidence to the contrary.  You blather on about "basic" formulas, but so far you are the one who has made faulty assumptions.  Like you assumed I based my formula on a "f = -bv" which is commical because 

 

1 hour ago, Uttamattamakin said:

The fact that you are so wrong that the above quote applies all while making it about the whole idea that I know what I litterally teach to other people and have a degree in..    It reminds me of when I teach remedial math and theres one student who is CERTAIN they are right and that both I and the computer homework system that graded them are both wrong.    Then they get angry when I do the problem again and show them that they are wrong.  Thats. you. 

In this topic you have needlessly utilized wrong mentalities in trying to defend your arguments.

 

The fact you seemed to so aggressively pursue that 10m is a realistic pipe size says it all.  Again, go back and look at the papers I posted, which are written by people smarter than yourself.

 

Pipe size is NOT the issue, materials required is NOT the issue, pulling a vacuum is not the issue.

 

Argue realistic things that are wrong about it, heat transfer, or whether the design will prevent enough air leakage to be beneficial on an energy sense.

 

Honestly you are acting like the teacher that marked my math answer wrong because while I got the correct answer I didn't use the way they understood so they thought I got lucky (without realizing I just used a different approach they hadn't taught, and were insistent the method I used was incorrect...until I asked them to take my test to the calc teacher who understood the method I used...the teacher still marked me wrong for not using the "correct" method until I took it to the administration).  If you are going to call me "so wrong" then you better back it up with actual formulas and actual references...instead of this frankly asinine approach of declaring yourself right without disputing why the basic equation that NASA teaches to pilots in regards to airplane drag.

[05032-Mendicant-Bias]

On 1/14/2024 at 8:41 PM, Uttamattamakin said:

It was not "obvious" that this would not work.

I'd argue Hyperloop was a success.

 

Musk's objective with the Hyperloop was to siphoon foundings for public infrastructure projects he loathes. He is vehemently against public transports.

[LAwLz]

11 hours ago, 05032-Mendicant-Bias said:

I'd argue Hyperloop was a success.

 

Musk's objective with the Hyperloop was to siphoon foundings for public infrastructure projects he loathes. He is vehemently against public transports.

No he didn't... He never admitted to that. There is a lot of creative interpretation going on in order to reach that conclusion. It might be right, but to say that he "admitted to it" is total BS.

[Elijah Kamski]

Insert Thunderfoot here