blackstar said:
RanulfC said:
It's not a "compromise" design as each "pod" would be optimized for its role. Highly specialized usually means highly costly too, and in fact the overall "efficiency" of passenger and cargo aircraft suffers seriously from the time it take to unload, load, and then launch again. Containerizing cargo actually increases overall throughput and eifficiency if done correctly, there is every indication it could do the same with passengers given the right airframes.
It absolutely is a compromise. That design is not optimized for fuel economy (high wing, twin booms--lots of drag). And it would carry around more mass than it needs to, such as the connectors for the pod and the twin booms.
I was actually addressing your comment "Trying to convert something that is not designed for the purpose to carry passengers is just not going to be efficient" specifically since the pods are going to be optimized for their respective role while the "airframe" itself will be less "economic" for fuel there would be savings due to less "down" time between flights and an overall higher flight rate. Fuel efficiency is currently one of the highest rated requirements for commercial aircraft, but this "priority" arrangment has changed before and could again.
If this makes so much sense, can you point to any airline designer that has seriously considered such a design in the last 20 years?
Boeing has looked at it, Airbus is part of the group studing a similar system for Europe, the main reasoning being that the overall passenger through-put on the larger, high capacity aircraft is hitting a limit and every study has shown that breaking up the single large loads into more easily managed smaller payloads is going to be a better path over the long run. The problem is that any study or work that assumes the use of current "specialized" aircraft requires major expansion of airports and processing facilities, along with a major increase in the number of aircraft that have to be bought and serviced per passenger load. In addition this also increases the fuel needs, reduces passenger comfort and traffic control issues.
One solution is a BIGGER aircraft such as the BWB but that brings in it's own issues with needing major changes to airport and processing facility infrastructure simply to allow the BWB to interface with passenger terminals. Worse from many airline perspectives the BWB is only going to make the "hub" situation worse with longer on-load/off-load times and much greater passengers numbers that have to be processed and routed to the "nodal" flight assignments which in and of itself is going to require more "nodal" aircraft, which are going to be competeing with the BWB for space at the terminal or new terminals. Passenger survey's have shown that an inheirent issue with the BWB is going to be passenger acceptance due to lack of windows and "off-center" passenger seating arrangements.
Another solution is something similar to the suggested system which would de-couple passenger in/out-processing, and "cabin" refurbishment between flights and drastically shorten the ground loiter time leading to a higher throughput rate overall.
The "Crossbow" style airframe is only one of several different types of vehicle being looked at and frankly it WAS specifically "designed" with Air-Launch rocket vehicles over other uses. Another example would be those suggested by Mike Snead:
http://mikesnead.net/
With his "Configurable Air Transport" system, though it would require two different airframes with all the extra design, construction, and operational issues that entails. Still it's been noted that combining the BWB with such a system eliminates a majority of the airport and passenger terminal issues as the "un-loading/loading" would be de-coupled from the actual facilties themselves.
"Clip-Air" is a similar concept though as I understand it they would like to develop it in the direction of combining with the European trans system.
http://clipair.epfl.ch/home
http://www.secretprojects.co.uk/forum/index.php?topic=19696.0
Though these are all "concepts" at this stage the very real need for more efficent air transportation has not been lost on commecial and military planners. Modular transportation has worked to make just about every other form of transportation more efficent, more economical, and to highly increase overall utility. It's probably past time that air transportation took the next logical step.
But "change" is difficult, especially given the nature of the change suggested and there is resistanct to undertaking the rather radical changes needed to bring these concepts into real-world use. However the writing is clear and despite the resistance I fully expect to see something similar to these concepts flying in the near future even if only for research purposes.
Randy