Help with transportation superhighway

[cfg83]

winkosmosis -

Originally Posted by winkosmosis

The reason for that is that the automakers and big oil lobbied against railroads, and in favor of government building more highways.

I thought the highway program was also part of a Cold-War strategy to have a highway system that could move miltary equipment quickly and efficiently. This served the dual-purpose of favoring the automobile industry.

I also thought that the airline industry (Boeing, McDonnell-Douglas, etc...) was favored over the railroad industry for similar reasons.

CarloSW2

[Ernie Rogers]

I'M STILL WAITING--ANYBODY OUT THERE HAVE ANY INFORMATION?

(Correction on Reynolds number: 65 million)

Ernie Rogers

Originally Posted by Ernie Rogers

Hello, guys,

About a week ago, I was asking for help on a little project, to predict the ideal high-efficiency car. Well, I have labeled that job "complete" and I'm on to a new one. (The document from the last project was posted today in the general efficiency forum.)

New project: To define the ultimate public transportation vehicle. Something better than a train, better than a bus, faster than a plane for short distances, say up to 200 miles. The premise of the new vehicle is that it will operate in a "transportation superhighway," a network with distributed control, with traffic routed for maximum throughput and efficiency.

The vehicle is presumed to travel on a rail and be small enough to provide near-point-to-point transportation. I am imagining a body of revolution sized to carry eight passengers--

7.8 ft diameter x 35 ft long (D/L = 0.21?)
200 mph design speed
Up in the air, no ground effect. Re = 20 million? (from memory)

My question: I guessed that a drag coefficient (based on frontal area) of Cd = 0.02 should be achievable. Could somebody help with this, verifying or improving this number? I was unable to find a place to get the information.

Ernie Rogers

[Bicycle Bob]

If you want "near point-to-point" you need either a lot of new rails, or two sets of wheels on this. Maybe you can keep the speed down on the road, to minimize the need for crash protection and weight. The optimum size will vary wildly, depending on location and time of day. If you build a rail system, please leave the vehicle options open, up to a set weight.

[Ernie Rogers]

Originally Posted by Bicycle Bob

If you want "near point-to-point" you need either a lot of new rails, or two sets of wheels on this. Maybe you can keep the speed down on the road, to minimize the need for crash protection and weight. The optimum size will vary wildly, depending on location and time of day. If you build a rail system, please leave the vehicle options open, up to a set weight.

Ah, excellent, Bob,

Thinking is definitely appreciated.

Ernie

[donee]

Hi Ernie,

Hey! If your going to fill up the train with people, then you got to fill up the Prius with people too. That makes for a 131/2 = 65.5 gmC02/passenger mile.

On your Cd question, yea, .025 might be doable. That is the Cd similar to a passenger aircraft such as a 787. The vehicle would need to have some sort of struts down to the track to support it high above the track to avoid compressibilty drag between the track and the body. The struts need to have minimun section area. Kinda like wings.

[Ernie Rogers]

Hello, Donee

That's a good point on the occupancy. In which case, a train uses more fuel /makes more CO2 than a Prius.

On the Cd, so far it looks like I need to lower it a notch

Originally Posted by donee

Hi Ernie,

Hey! If your going to fill up the train with people, then you got to fill up the Prius with people too. That makes for a 131/2 = 65.5 gmC02/passenger mile.

On your Cd question, yea, .025 might be doable. That is the Cd similar to a passenger aircraft such as a 787. The vehicle would need to have some sort of struts down to the track to support it high above the track to avoid compressibilty drag between the track and the body. The struts need to have minimun section area. Kinda like wings.

[ai_vin]

Not sure if this is what you want but - http://www.2020engineering.com/pdf/2020eels.pdf

[ai_vin]

BTW that link mentioned the CyberTran system this you can find more about here- CyberTran International

[aerohead]

Originally Posted by Ernie Rogers

I'M STILL WAITING--ANYBODY OUT THERE HAVE ANY INFORMATION?

(Correction on Reynolds number: 65 million)

Ernie Rogers

The ideal teardrop form(about 2.7:1 fineness ratio) outside of ground effect has a Cd 0.04.I believe Morelli developed a low drag form of which Aptera borrows from.It was never tested in ground-effect.---- Any lengthening of the ideal teardrop body of revolution exhibits an increase in drag do to skin friction.I believe Cd 0.04 is the limit.Any environmental structure within close proximity will degrade the Cd.

[trebuchet03]

Originally Posted by Ernie Rogers

Okay, guys,

I think you have wandered off the topic. (It was aerodynamics of a high speed car without ground effect.)

Shinkansen Bullet Train....................100 gm CO2 /passenger mile
U.S. Train.......................................95
Transit Bus.....................................64
Prius (two people)..........................131
Airlines.........................................3 23
X Prize car (100 mpg, 2 people)..........59

New 8 passenger rail car...................13 gm CO2e /mile

From another angle that looks a a slightly bigger picture...

BTU per passenger mile (2006)
Cars............................ 3512
Personal Truck.............. 3944
Motorcycles................. 1855
Demand Response*........ 14301
VanPool....................... 1322
Buses (transit).............. 4235
Air (certified Route)........ 3261
Rail (all)........................ 2816

*Dispatched services

Source
Chapter 2 Energy - Transportation Energy Data Book

What's confusing me is why you want to ignore ground effect while having rail (I understand you're thinking raised rail - but losses from these stationary objects will be significant).

But that said, I concur with aerohead - I don't remember the specific source, but I have read of theoretical limits approaching .04.