Opinions on a Hypersonic Tunnel based Transportation System

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Discussion Overview

The discussion revolves around a proposed hypersonic tunnel-based transportation system, exploring its feasibility, potential challenges, and alternative approaches. Participants engage in technical reasoning, conceptual clarifications, and debates regarding the implications of using hydrogen and the design of the system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the primary challenge of hypersonic travel is the need to remove air in front of the vehicle, proposing a design that uses a tube filled with gas to reduce drag.
  • Another participant warns against using hydrogen due to safety concerns, referencing historical incidents like the Hindenburg disaster.
  • Concerns are raised about the potential for increased drag due to wall/blockage effects in the tunnel, questioning the effectiveness of the proposed design.
  • Participants discuss the challenges of steering a hypersonic vehicle in a tunnel, with one suggesting that control surfaces and retro rockets could be used.
  • There is skepticism about the ability of metallic foam to mitigate shockwaves within the tunnel, with one participant arguing that shockwaves would remain strong until they contact the wall.
  • Another participant highlights the complexity of hypersonic flight, stating that it involves more factors than just drag, including viscosity.
  • One participant expresses a willingness to explore alternative gases for the system, emphasizing the need for a gas with a good lift-to-drag ratio.
  • There is a suggestion that if the tunnel needs to be large enough to avoid ground effects, it may be more practical to remain above ground.
  • A later reply frames the discussion as an academic exercise, encouraging radical ideas while acknowledging the challenges faced by the aerospace community.

Areas of Agreement / Disagreement

Participants express a range of opinions, with no consensus reached on the feasibility or safety of the proposed hypersonic tunnel system. Multiple competing views remain regarding the design, materials, and potential challenges associated with hypersonic travel.

Contextual Notes

Participants acknowledge limitations in their understanding of quantitative drag analysis and the complexities of hypersonic flight, indicating that further exploration and analysis are needed to address these issues.

  • #31
Ground effects at 220 mph and ground effects at 3800 mph are entirely different animals. In fact, to my knowledge, no work has been done on ground effects at that speed because it simply isn't practical. It is a disaster waiting to happen. One tiny anomaly in the flight and the whole thing goes up in a fireball. There just is no time for corrections at that speed.
 
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  • #32
I'm sorry, but do you know how expensive it would be to:
1) Build a tunnel across the Atlantic Ocean that could support itself and the stuff inside it
2) make the train chamber a near VACUUM for its entire length?

First off, the pumps required to maintain vacuum alone would probably use more electricity per year than New York State. Not to mention the maintenance required (this means constant trips to the middle of the ocean for repairs on pumps and generators and associated safety controls). Then you have to worry about maintaining the line. Out there in the middle of the Ocean.

Then, you've got the cost of running the stretch of mag-lev and all the maintenance and repair that goes into that...And you've got to have a method of retrieving passengers if the train malfunctions while way out there along the line (I guess you could put rest stops/platforms out there every so often, but still).

This just does not seem like a more cost effective route than planes...At least not for a while.
 

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