6 ms·

People always seem to grossly underestimate the cost to crew-rate, and then passenger-rate vehicles. Especially with new technology, which usually involves kil

by ajarmst 10y ago

People always seem to grossly underestimate the cost to crew-rate, and then passenger-rate vehicles. Especially with new technology, which usually involves killing people along the way. It is much, much, more expensive to develop a system to the point where you can put a fare-paying passenger on it than it is to take it to where you can reliably put a sensor package in it or even a test pilot that you expect to survive. The cost of an uncrewed scale model isn't even noise in the cost of a full-size passenger-rated project, and its success isn't particular predictive of the actual project. The sonic boom problem isn't trivial. You need to be able to land the vehicle near cities, because that's where the customers are. That means you have to spend a good chunk of time (maybe a long chunk of time if you have to orbit waiting to land) flying low and slow---a vehicle designed to use fuel efficiently when high and supersonic is almost by definition going to be less efficient than traditional vehicles when forced to fly in that regime. Which means it has to carry a lot of fuel, which means weight, which means ... etc. As other commenters have noted: shaving an hour or two off of time spent at the terminal will generally be much more effective in speeding up travel. There is another city a three-hour drive from where I live, and it is faster for me to drive there than fly. And replacing the aircraft with a missile wouldn't change that.

6stringmerc 10y ago
Such a well written summary I think it should pretty much be a footnote to any of the super sonic / hyper sonic / quad-copter-automated-flying-thingy forward looking statements. I think projects like Boom are perfectly fine for rich billionaires to throw money at in their spare time, because they still run into physics and logistics. In doing research for a project, I came across some Annual Reports for the company Sabre. Some might recognize the name, as they were an in-house tech / logistics / travel operations company for American Airlines that got spun off into its own entity years back. Point being, they have a vested interest in air travel, and over and over, the CEO was concerned and frustrated by the lack of modernization in flight systems and overall system improvements. A very consistent theme, and I can't disagree with him. Looking at it another way, the scale of persons affected by system upgrades and improvements drastically overshadows those who would, uh, gain from supersonic travel. Just makes sense.
- anovikov 10y ago
  manned quad-copter is fine. i am sure it can be man-rated with tolerable expenses and will quite soon become a useful way of within-city transportation. supersonic passenger plane is in completely different league...
  - ajarmst 10y ago
    Crew-rated is radically different from passenger-rated in basic safety requirements. The problem with quad copters is that they're unstable in flight after the loss of only one engine, and lack sufficient mass in the propellors to effectively autorotate. That makes nearly any propulsion or control system failure in a crewed quad copter a probable hull-loss and crew-loss event. Even test pilots have problems with flying under those conditions. The problem isn't lifting a human to a useful height and velocity---the Romans solved that with catapults. The problem is being able to reasonably assure them that you can return them to earth safely, reliably, and sufficiently inexpensively.
    - 6stringmerc 10y ago
      My logic was more from an insurance perspective related to a point you brought up - re: transportation improvements will likely be related to population dense environments. Looking at the quad copters I have some doubts regarding navigation and/or performance during a catastrophic failure where others might be put at risk. That's not an unreasonable concern for life and property. As you noted, again, there are high thresholds regarding crew and passenger parameters. I think those also extend to functional operations. For commercial aviation, there is a good 50+ years of accident records and ways that companies have paid out for tragedies and whatnot. Adding in a new component - the quad copter model - is most definitely outside of the norm and I think will be viewed as high risk at first, even if there are great financial rewards to be reaped down the line pending success.
    - elmar 10y ago
      at the moment the electrical quad copter bigest problem is the lack of autonomy 15 minutes max time.
knz 10y ago
Isn't the main benefit of supersonic flight going to be seen over the oceans where noise concerns are less important? It's 12 hours from LAX to AKL (New Zealand). If they could get that down to six for a reasonable price there is a market. I suspect there would be even more demand for flights to Asian business hubs.
- ajarmst 10y ago
  True, but the fuel to get up to that altitude is a significant cost that can't be ignored, and the mass must be carried at takeoff (unless you want to solve the problem the way the USAF does, but I don't even want to think about passenger-rating in-flight refueling). The design flaw that finally killed the Concorde was precisely related to that --- the need for large fuel tanks and light structures left the vehicle very vulnerable to hull damage. At the other end, you have to make sure you're taking sufficient fuel for diversion to alternate airports (and there might not be a lot of airports willing/capable of taking the vehicle---that also affected the Concorde) as well as time to orbit waiting for a landing slot (if LAX is your destination, that's non-trivial). This already affects standard passenger routes --- short hops are more expensive because the aircraft doesn't spend much (or any) time at cruise altitude, where they're much more fuel-efficient. Yes, obviously these vehicles would be more economical for long over-water flights, but the problem is only partially mitigated by a longer time in an efficient regime. Those takeoff/landing costs don't go away.
ajarmst 10y ago
I forgot to add a quote from an engineer I used to work with: "Safe enough for a test pilot is very different from safe enough for the test pilot's kids."

by ajarmst 10y ago

6stringmerc 10y ago

Such a well written summary I think it should pretty much be a footnote to any of the super sonic / hyper sonic / quad-copter-automated-flying-thingy forward looking statements. I think projects like Boom are perfectly fine for rich billionaires to throw money at in their spare time, because they still run into physics and logistics. In doing research for a project, I came across some Annual Reports for the company Sabre. Some might recognize the name, as they were an in-house tech / logistics / travel operations company for American Airlines that got spun off into its own entity years back. Point being, they have a vested interest in air travel, and over and over, the CEO was concerned and frustrated by the lack of modernization in flight systems and overall system improvements. A very consistent theme, and I can't disagree with him. Looking at it another way, the scale of persons affected by system upgrades and improvements drastically overshadows those who would, uh, gain from supersonic travel. Just makes sense.

anovikov 10y ago
manned quad-copter is fine. i am sure it can be man-rated with tolerable expenses and will quite soon become a useful way of within-city transportation. supersonic passenger plane is in completely different league...
- ajarmst 10y ago
  Crew-rated is radically different from passenger-rated in basic safety requirements. The problem with quad copters is that they're unstable in flight after the loss of only one engine, and lack sufficient mass in the propellors to effectively autorotate. That makes nearly any propulsion or control system failure in a crewed quad copter a probable hull-loss and crew-loss event. Even test pilots have problems with flying under those conditions. The problem isn't lifting a human to a useful height and velocity---the Romans solved that with catapults. The problem is being able to reasonably assure them that you can return them to earth safely, reliably, and sufficiently inexpensively.
  - 6stringmerc 10y ago
    My logic was more from an insurance perspective related to a point you brought up - re: transportation improvements will likely be related to population dense environments. Looking at the quad copters I have some doubts regarding navigation and/or performance during a catastrophic failure where others might be put at risk. That's not an unreasonable concern for life and property. As you noted, again, there are high thresholds regarding crew and passenger parameters. I think those also extend to functional operations. For commercial aviation, there is a good 50+ years of accident records and ways that companies have paid out for tragedies and whatnot. Adding in a new component - the quad copter model - is most definitely outside of the norm and I think will be viewed as high risk at first, even if there are great financial rewards to be reaped down the line pending success.
  - elmar 10y ago
    at the moment the electrical quad copter bigest problem is the lack of autonomy 15 minutes max time.

knz 10y ago

Isn't the main benefit of supersonic flight going to be seen over the oceans where noise concerns are less important? It's 12 hours from LAX to AKL (New Zealand). If they could get that down to six for a reasonable price there is a market. I suspect there would be even more demand for flights to Asian business hubs.

ajarmst 10y ago
True, but the fuel to get up to that altitude is a significant cost that can't be ignored, and the mass must be carried at takeoff (unless you want to solve the problem the way the USAF does, but I don't even want to think about passenger-rating in-flight refueling). The design flaw that finally killed the Concorde was precisely related to that --- the need for large fuel tanks and light structures left the vehicle very vulnerable to hull damage. At the other end, you have to make sure you're taking sufficient fuel for diversion to alternate airports (and there might not be a lot of airports willing/capable of taking the vehicle---that also affected the Concorde) as well as time to orbit waiting for a landing slot (if LAX is your destination, that's non-trivial). This already affects standard passenger routes --- short hops are more expensive because the aircraft doesn't spend much (or any) time at cruise altitude, where they're much more fuel-efficient. Yes, obviously these vehicles would be more economical for long over-water flights, but the problem is only partially mitigated by a longer time in an efficient regime. Those takeoff/landing costs don't go away.

ajarmst 10y ago

I forgot to add a quote from an engineer I used to work with: "Safe enough for a test pilot is very different from safe enough for the test pilot's kids."