Evacuated tube transport the end of Airlines?

[Brons2]

Originally Posted By: Syntheticuser
I dislike airlines with a passion. I've had god awful service the few times I did fly. It sucked. My experience, not yours. Some people on this forum hate guns, diesel trucks, good looking women...things that I say help make life more enjoyable.
Astro, you make it out to be that I had not paid for first class tickets the fee times i flew. I did, give me my monies worth is what I wanted...never got it. I pay more for quality, when I can get better products or services.


You probably had unrealistic expectations when you traveled via airline. I personally think the service is fine, but I know what to expect when I get to the airport and what to do when I get on the airplane, which makes things go more smoothly.

And yes I hate guns and diesel trucks, thanks.

And Baylor. I definitely hate Baylor.

 

[Astro14]

Originally Posted By: y_p_w
Originally Posted By: PeterPolyol
Dead in 90 seconds!

Now that you think of it the only things that'll 'blow up' are the gasses in the body. I'd imagine perhaps abdominal bloating or instant tooting/belching depending on the easiest exit... and then the fatal dissociation of dissolved gasses from all cells... a good time all around.

Can you imagine, an entire track of 'vacuum tube' is a heck of a lot of volume to re-pressurize in an emergency. One exploding car would barely affect the total vacuum and the occupants would surely perish in agony, without some type of safety isolation.

Isn't the concept that it's a relative vacuum in front pushed along by air from behind? A lot of the proposals don't include a system where it's a total vacuum.


Total vacuum is necessary to get the high speed.

Pushing air around, like a big version of the old bank teller tubes, limits the speed to a few hundred mph...

All of the linked concepts are hypersonic. Which requires total vacuum.

 

[mightymousetech]

Originally Posted By: L_Sludger
I'm thinking,
If the pressurized tube loses vacuum, it won't be catastrophic to the occupants of the capsule as the capsule would have a failsafe mode for that; it would merely traverse the tube in a backup mode that doesn't enjoy the frictionless vacuum efficiency or speed.
What about if the capsule's hull was breached, and the occupants were then exposed to vacuum? Ugly!!! Wouldn't that be like a space suit failing during a spacewalk?


If the pod ran into a pocket of air at those speeds, it would be like running into a brick wall at 1000 km/hr.

 

[Shannow]

Originally Posted By: y_p_w
Isn't the concept that it's a relative vacuum in front pushed along by air from behind? A lot of the proposals don't include a system where it's a total vacuum.


That would be a horridly inefficient way of transporting anything.

read some of my earlier posts about pulling and breaking a vacuum...then imagine "sealing" the "bullet", and the friction that would incur.

 

[ls1mike]

I fly often for work, and after spending time on submarines you would think flying would be no big deal. I don't like it. I am a nervous flyer.

Having said that I have never had a problem with the airlines or TSA. I treat those people how I want to be treated and guess what? I get treated pretty well. Sure it is crowed and security sucks but if you go expecting that you won't have a problem. Go in and act like a jerk guess what? That is how you will be treated.

You know what makes flying suck? Passengers! Passengers who feel they are owed something, passenger who think they are special...Blah.

You know what else sucks? Check your bag! Don't try to squeeze your refrigerator in the overhead bin.

Tube travel? I don't see it being very efficient in large volume or where there are lots of stops.

 

[PandaBear]

Originally Posted By: Astro14
Originally Posted By: PandaBear
Originally Posted By: MinamiKotaro
The passengers would "merely" suffocate.


Like they would inside an airplane. There are mature technologies to deal with that.



What technologies would those be?

Just curious. When an airplane loses pressurization, the outside pressure is about 25KPa (vs. 100KPa at sea level). Instant vacuum is far, far worse than a depressurization at 35,000 feet.

Further, the airplane is going to descend, rapidly, to an altitude at which breathing is possible.

This isn't possible inside the evacuated tube. It has to maintain vacuum to function.

So, what mature technologies exist to allow people to survive in a vacuum for the length of the trip?

Current O2 masks won't work. Within seconds, our tube passengers will be suffocating, because they can't inhale (there's a vacuum outside their lungs, so inside their lungs won't be lower pressure, as it is ordinarily). They will be continually exhaling, unless they can get a high pressure mask, which isn't commercially available. If they survive those few seconds and don the pressure mask, they might not have their lungs rupture from the internal pressure.

Then, they merely have to deal with the phase transition of the water in their blood and tissues from liquid to gas... At that low a pressure, depending on temperature, a condition called ebullism,will cause tissue swelling and bruising due to the formation of water vapor under the skin; at worst, it can give rise to an embolism, or blood vessel blockage due to gas bubbles in the bloodstream.

So, sure, they could wear pressure suits, like military pilots do above 50,000', which would require some training and careful (read: expensive) fitting, and then they could survive decompression of the "car" in the tube...but it's not exactly viable, or mature, technology...


You are not making sense. Have you seen astronauts wear suits inside the space station when not going outside?

It is just like an airplane if redundant control signals are in place. No ping from pressure sensors inside the vehicles for a fraction of a seconds? release the safety valve and let air in, and of course, keep a pressurized tank of liquid oxygen inside the vehicle and release it if pressure drop below certain level.

It is mature technology, and it is not that expensive, and they are used everyday in hospital (oxygen tank), pressure cooker (safety valve), and airplane (redundant control systems).

So far I haven't seen astronauts exploded because of a failed space station seal yet.

 

[PandaBear]

Originally Posted By: Shannow
Originally Posted By: y_p_w
Isn't the concept that it's a relative vacuum in front pushed along by air from behind? A lot of the proposals don't include a system where it's a total vacuum.


That would be a horridly inefficient way of transporting anything.

read some of my earlier posts about pulling and breaking a vacuum...then imagine "sealing" the "bullet", and the friction that would incur.


Agree. However, most fast transportation is not the most efficient. Hence we still use ship and slow trains for cheap transports, not air or high speed rail.

I still think unless the population density is high it is not worth the trouble.

 

[Shannow]

Originally Posted By: PandaBear
Agree. However, most fast transportation is not the most efficient. Hence we still use ship and slow trains for cheap transports, not air or high speed rail.


Clearly you don't get just HOW inefficient "pushing" a vahicle into an evacuated tube is...then you have to evacuate that entire section again for the next section.

If you had seals that would actually obturate the "bullet" in the cylinder, then you'd get no forward motion, as the drag would be too high.

Go back and re-read my technical parts...I'm talking from a position of knowing, as first thing we have to do in running up a turbine is evacuate the steam side of the turbines and condenser...1,000hp for about 20 minutes. Then leave 500hp running 24/7 to take care of air inleakage.

Make it 100 miles of 10' tube, and the power consumption will be enourmous...and you won't be "wasting" it just to push a bullet train around.

It will be evacuated and held there.

And if the life support fails in the evacuated tube, it will literally take 10+ minutes to get the volume back to breathable.

 

[Astro14]

Originally Posted By: PandaBear
Originally Posted By: Astro14
Originally Posted By: PandaBear
Originally Posted By: MinamiKotaro
The passengers would "merely" suffocate.


Like they would inside an airplane. There are mature technologies to deal with that.



What technologies would those be?

Just curious. When an airplane loses pressurization, the outside pressure is about 25KPa (vs. 100KPa at sea level). Instant vacuum is far, far worse than a depressurization at 35,000 feet.

Further, the airplane is going to descend, rapidly, to an altitude at which breathing is possible.

This isn't possible inside the evacuated tube. It has to maintain vacuum to function.

So, what mature technologies exist to allow people to survive in a vacuum for the length of the trip?

Current O2 masks won't work. Within seconds, our tube passengers will be suffocating, because they can't inhale (there's a vacuum outside their lungs, so inside their lungs won't be lower pressure, as it is ordinarily). They will be continually exhaling, unless they can get a high pressure mask, which isn't commercially available. If they survive those few seconds and don the pressure mask, they might not have their lungs rupture from the internal pressure.

Then, they merely have to deal with the phase transition of the water in their blood and tissues from liquid to gas... At that low a pressure, depending on temperature, a condition called ebullism,will cause tissue swelling and bruising due to the formation of water vapor under the skin; at worst, it can give rise to an embolism, or blood vessel blockage due to gas bubbles in the bloodstream.

So, sure, they could wear pressure suits, like military pilots do above 50,000', which would require some training and careful (read: expensive) fitting, and then they could survive decompression of the "car" in the tube...but it's not exactly viable, or mature, technology...


You are not making sense. Have you seen astronauts wear suits inside the space station when not going outside?

It is just like an airplane if redundant control signals are in place. No ping from pressure sensors inside the vehicles for a fraction of a seconds? release the safety valve and let air in, and of course, keep a pressurized tank of liquid oxygen inside the vehicle and release it if pressure drop below certain level.

It is mature technology, and it is not that expensive, and they are used everyday in hospital (oxygen tank), pressure cooker (safety valve), and airplane (redundant control systems).

So far I haven't seen astronauts exploded because of a failed space station seal yet.


So, public transport at space station cost?

Let's see, $100 billion for a six-people station that has enough redundancy to address those failures....yep, that'll be...cost competitive in your tube....

I was applying the military aircraft redundancy standard. And we wore pressure suits above 50,000' which is a long way from vacuum. But those vehicles only cost millions apiece. So, I chose the simpler cheaper vehicle.