The Hyperloop design is trying to achieve the following objectives. (57 page pdf)
The tesla motors pdf copy could get overloaded. Here is the pdf on Spacex
* Safer
* Faster
* Lower cost
* More convenient
* Immune to weather
* Sustainably self-powering
* Resistant to Earthquakes
* Not disruptive to those along the route
Overcoming the Kantrowitz Limit
Whenever you have a capsule or pod (I am using the words interchangeably) moving at high speed through a tube containing air, there is a minimum tube to pod area ratio below which you will choke the flow. What
this means is that if the walls of the tube and the capsule are too close together, the capsule will behave like a syringe and eventually be forced to push the entire column of air in the system. Not good.
Nature’s top speed law for a given tube to pod are a ratio is known as the Kantrowitz limit. This is highly problematic, as it forces you to either go slowly or have a super huge diameter tube. Interestingly, there are usually two solutions to the Kantrowitz limit
1) where you go slowly
2) where you go really, really fast.
The latter solution sounds mighty appealing at first, until you realize that going several thousand miles per hour means that you can’t tolerate even wide turns without painful g loads. For a journey from San Francisco to LA, you will also experience a rather intense speed up and slow down. And, when you get right
down to it, going through transonic buffet in a tube is just fundamentally a dodgy prospect.
Both for trip comfort and safety, it would be best to travel at high subsonic speeds for a 350 mile journey. For much longer journeys, such as LA to NY, it would be worth exploring super high speeds and this is probably technically feasible, but, as mentioned above, I believe the economics would probably favor a supersonic plane.
The approach that I believe would overcome the Kantrowitz limit is to mount an electric compressor fan on the nose of the pod that actively transfers high pressure air from the front to the rear of the vessel. This is like having a pump in the head of the syringe actively relieving pressure.
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The tesla motors pdf copy could get overloaded. Here is the pdf on Spacex
* Safer
* Faster
* Lower cost
* More convenient
* Immune to weather
* Sustainably self-powering
* Resistant to Earthquakes
* Not disruptive to those along the route
Overcoming the Kantrowitz Limit
Whenever you have a capsule or pod (I am using the words interchangeably) moving at high speed through a tube containing air, there is a minimum tube to pod area ratio below which you will choke the flow. What
this means is that if the walls of the tube and the capsule are too close together, the capsule will behave like a syringe and eventually be forced to push the entire column of air in the system. Not good.
Nature’s top speed law for a given tube to pod are a ratio is known as the Kantrowitz limit. This is highly problematic, as it forces you to either go slowly or have a super huge diameter tube. Interestingly, there are usually two solutions to the Kantrowitz limit
1) where you go slowly
2) where you go really, really fast.
The latter solution sounds mighty appealing at first, until you realize that going several thousand miles per hour means that you can’t tolerate even wide turns without painful g loads. For a journey from San Francisco to LA, you will also experience a rather intense speed up and slow down. And, when you get right
down to it, going through transonic buffet in a tube is just fundamentally a dodgy prospect.
Both for trip comfort and safety, it would be best to travel at high subsonic speeds for a 350 mile journey. For much longer journeys, such as LA to NY, it would be worth exploring super high speeds and this is probably technically feasible, but, as mentioned above, I believe the economics would probably favor a supersonic plane.
The approach that I believe would overcome the Kantrowitz limit is to mount an electric compressor fan on the nose of the pod that actively transfers high pressure air from the front to the rear of the vessel. This is like having a pump in the head of the syringe actively relieving pressure.
Read more »
