The more you live the more you realize how things change. While your going through it,change sometimes seems to take forever but only when we reflect back does it seem so obvious and apparent. Oddly one area of change that hasn’t progressed much since my birth in the early seventies is that of high-speed travel, pretty much jet travel was and still is the predominant way most of us can get from place to place the fastest.
Jet Speed… still the same as your grandpa’s
So that’s been forty plus years … And lets see how much we have improved.
|Year introduced||Airplane (Model)||Cruise Speed||Mach #|
|1958||[wiki] Boeing 707-[/wiki]320||604 mph||0.89 Mach|
|2011||[wiki]Boeing 787 [/wiki] Dreamliner||567 mph||0.85 Mach|
Net gain. 6% slower speed today via air travel than in 1958 (in all fairness the Boeing 787 is a ton more fuel efficient and has much longer range). But considering the Boeing 707 ushered in the jet over 55 years ago I think it’s a little disheartening. Its not that aeronautical engineers don’t know how to make airplanes go faster, quite the contrary many military planes break the sounds barrier all the time. The problem is doing it within commercial economic constraints it’s just not practical, case in point the [wiki]Concorde SST[/wiki].
The economics and technical challenges of supersonic flight make it unlikely that a faster air travel is something coming to the masses in the near future. Serious technical challenges crop up once you get to speeds approaching mach 6 , heating and structural challenges become a real problem, plus the cost of in terms of fuel load to push through the atmosphere at increasing hi-speeds is pretty prohibitive and even today’s top high-speed fighters require in-air refueling if the gun open the throttles for too long. So in nutshell high-speed air travel short of rocketry is not likely anytime in the near future.
High speed “rail”, re-imagined
Which brings me to the point of this post, While i likely may not see it in my lifetime, my feeling is that the future of hi-speed transportation is not in the skies but on the ground and more likely in a tube. Yes I’m talking about about high-speed rail or more precisely very high-speed evacuated tube maglev .
Basically this involves placing a magnetic levitation train on a monorail type track, inside a partially(or fully) vacuum sealed tube/tunnel . Then through magnetic induction or perhaps even jet power we begin to propel the train at very high velocities inside this evacuated tube. This solution solves a few fundamental challenges in one fell swoop. First by being inside a near vacuum you greatly eliminate or reduce the aerodynamic loads on a high speed vehicle, no wind resistance very high speeds with minimal energy expendetures. You greatly reduce thermodynamic (heating) effects for similar reasons, finally the maglev solves the last issue by minimizing friction and surface contact issues associated with high velocities. What this means is that we can literally accelerate a train to high speed mach numbers 3,5,10,25 all with minimal energy requirements .
High Speed rail, human factors limit upper limit
Of course there are some challenges with this sort of high speed travel.
Construction costs This is by far the biggest hurdle, at the moment its prohibitively expensive to lay down new regular railroads in any densely populated modern country, there simply isn’t the available land. Not to mention the per mile cost, but i suspect perhaps using TBR (Tunneling boring machines) with a combination of future automated construction techniques coupled with material and building advances will shrink initial costs. And once the benefits are realized costs can be amortized over a 10 to 50 year period.
Human factors: Once the economic aspects and technical considerations are resolved, we run into perhaps the biggest limiting factor , human physiology. Its a fairly daunting physics problem how to deal with high-g loads for sustained periods of time. Keep in mind that accelerations and deceleration’s , turns , climbs and descents at cruising speeds of 4000 mph pose a real hazard to the passengers. This means any such system needs to be planned carefully to avoid such high g loads. Emergency stops would be pretty hairy since coming to a stop at 4,000mph requires time and would produce some unwanted g-loads on passengers, so slowing down will certainly pose a great challenge. These are all likely solvable, after all people travel in airplanes at 500-600mph everyday without major issues.
Benefits and of high speed travel
Now lets get into some fun theoretical s, assuming a cruising speed of 4000 mph, which is a very doable velocity, and assuming a acceleration time slightly faster than an airplane taking off. of 1G 9.8 m/s/s (can be adjusted) to reach the cruising speed.
Time to reach cruising speed at 2G (18.6 m/s/s) acceleration
|Start||Destination||Distance (miles)||Cruise Speed||Travel time|
|New york||Chicago||790 miles||4000 mph||30min|
The travel times aside the other benefits include
Comfortable smooth ride without turbulence or uncomfortable cabin pressure
Larger space to walk around much like todays long haul train cars
Faster city-center to city-center transit times
Ability to commute to work
Short of teleportation or near FTL travel this may be the most realistic and practical travel solution that may become available in our or our children s lifetimes. I do hope i can at least see a working prototype someday. That would be fantastic. What are your thoughts.