5 ms·

The main issue is not cost, but safety and the disturbance of others. Safety: If you crash in a car, its very likely that you survive. With these a crash is ve

by sydd 4y ago

The main issue is not cost, but safety and the disturbance of others. Safety: If you crash in a car, its very likely that you survive. With these a crash is very likely deadly. To reach safety levels like commercial airplanes costs will need to rise tremendously. A commercial jet needs maintenance and checks after each flight by trained personnel, high quality parts that can be tracked from the refinery,... Privacy: You dont want these flying over your house 7/24. They fly much lower than commercial planes, with a mediocre camera you could spy on anyone. Crime: What if you divert one? Will there be security checkpoints at the entrance? Weather: I'm no aviation expert, but these look... flimsy. Are they able to run on cold weather? (batteries last much less in cold) Are they able to run in storms? Likely not, even commercial planes avoid them. Then I guess they suspend the service during storms, since with their "local" distances as big as the circumference of a storm cloud?

hef19898 4y ago
Safety and weather are covered by certification requirements. Those will be somewhere between small aircraft and helicopters with some eVTOL specifics. If it gets certified those bases are covered. Privacy: Regulated airspace is your friend, plis why wait for one those if you can have your own drone for the price of one Lilium ticket. Crime: Regulations also cover airport operations, so that base will be covered as well. For me the question is not if those aircraft are goong to fly (they will if it os technically possible and people fund development), but rather whether there is an actual market for those big enough to make the manufactirers and operators viable businesses. The last qiestion is hard (IMHO impossible) to answer without getting them to market first.
- sokoloff 4y ago
  There are certification requirements for both the aircraft and Ops Spec approvals for Part 135 (on-demand charter) operations. I can see that these would be certified to fly (and thus eligible for Part 91 (private) operations) far more easily than the more stringent requirements for Part 135 charter operations. The FAA thinking is that you have greater understanding as a passenger on a Part 91 operation and are better able to judge the risk yourself, whereas a Part 135 (charter) or Part 121 (scheduled airline) operation, the public cannot effectively judge the safety of the operation so the FAA holds them to a higher standard. Single engine Part 135 is possible, but there's a large amount of focus on redundancy: https://www.aviationconsumer.com/industry-news/single-engine-135/ https://www.aviationconsumer.com/industry-news/single-engine...
sokoloff 4y ago
These seem to compete more in the helicopter realm than the airliner realm. That's likely to be true of the relative level of safety of this vs a helo vs an airliner. (I've sometimes quipped that helicopters are one of the primary predators of billionaires.) While the stated/projected costs (which I doubt will be achievable), these would compete very favorably against a helicopter on a cost basis. Without the ability to auto-rotate (or a functional equivalent level of safety system), there's no way I'm getting in one nor recommending my family get in one [and I'm perfectly happy flying my family in single engine piston aircraft at night].
- lambda 4y ago
  eVTOL have to be designed to the same safety standards as other aircraft; and in fact, they will be held to slightly higher design safety standards due to their novelty, required to meet safety standards that otherwise only apply to larger transport category aircraft. You are right, eVTOL cannot autorotate, but electric motors can be far more reliable than internal combustion engines, with many fewer failure modes. Additionally, they are much lighter, and so you can have much greater redundancy. There is considerable redundancy in the lift motors on these aircraft, so one or in many cases more than one lift motor can fail while still providing safe and controllable flight. The exact level of redundancy needed is verified via probabilistic risk analysis, considering failure probabilities of different components, and as mentioned the target failure rate will be lower for these than for equivalent sized conventional aircraft due to their novelty. While there's still a lot of design and development work to do, I'd be very surprised if these didn't end up much more reliable and less prone to failure than helicopters and single engine airplanes. Note: I work for one of these startups, so I may be a bit biased, but I also have insight into the design process and safety and redundancy of systems are absolutely a top concern.
  - lambda 4y ago
    Oh, I should also say, for a helicopter autorotation is only particularly helpful if you have enough forward airspeed or height to initiate it. Helicopters come with an HV diagram indicating safe flight envelope, such that autoration could be initiated in case of an engine failure, or you are low enough for a crash to be survivable if you do not have enough height or airspeed for autoration. https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velo... In an eVTOL, if you have enough height or velocity, you should be able to glide on the wing. So you'll be wanting to keep yourself in the appropriate region of the HV curve, and your emergency engine out procedure will be much more like a conventional fixed wing aircraft, rather than a helicopter.
lambda 4y ago
I work for one of these startups, Beta. We are focusing on a slightly different market than the other entrants; we're focusing initially on cargo rather than passenger transit. One initial customer is United Therapeutics, for transporting organ transplants and artificial organs to hospitals. Another is UPS, for getting air freight from airports to distribution centers; cutting out the truck trip can save a ton of time there. We are also making a passenger variant, but since the regulatory and NIMBY concerns for the passenger air taxi market present a lot of risk, we're not betting solely on that market like a lot of the other companies are. This helps with a lot of the concerns raised in this thread. In fact, another one that I'm not sure has been brought up is vertiport design and siting concerns; right now standards on vertiports are still a work in progress, and there are questions about whether it will be feasible to get them installed, because even with vertical takeoff and landing you generally need to keep approach angles of about 15° clear, which means once a vertiport is installed you need to limit the heights of any surrounding buildings to keep the approach clear. To address a few of your other concerns: we're located in northern Vermont, we know cold weather. Actually, for our use case hot weather tends to be more of a concern; batteries and motors heat up when used, especially in the very high power vertical lift phase, so our limitations there tend to be thermal and cold air provides better cooling. Our charging stations also include air for cooling and warming the batteries; so you should be able to avoid the issues with batteries being cold on startup with our air system. All aircraft have limitations on weather that they can be flown in; crosswind limits for takeoff and landing, etc. As very lightweight aircraft, with high lift/drag, these will be somewhat lower than the limits for your big jumbo jets, but will be high enough to be useful in a lot of weather. All aircraft have requirements for design and testing for HIRF (high intensity radiated field/lightning), so these will all be certified to the same standard there. Aircraft can optionally be certified for flight into known icing conditions (FIKI); I believe our plan is to have the capability, but as an optional add on, as it requires a number of heating elements which add weight and complexity. But overall, the weather concerns shouldn't be too much different than for other small aircraft. As far as safety goes, that's obviously a concern in any aircraft. One advantage of electric aircraft is that electric propulsion systems are far mechanically simpler, with far fewer moving and wearing parts. The only real wear item of concern are the main bearings on the motors, and the landing gear. So maintenance intervals can be much longer than with ICE aircraft, and I expect reliability to be considerably higher. Additionally, electric motors can be much smaller and lighter, and thus can be made redundant. Each propeller on our aircraft will be driven by multiple independent motors (probably can't say the exact configuration at the moment), so that motor failures can be tolerated without catastrophic consequences.
willyt 4y ago
Safety can be solved with a parachute that lands the whole aircraft in the event of a catastrophic failure. These are already fitted to high end GA aircraft like Cirrus.

by sydd 4y ago

hef19898 4y ago

Safety and weather are covered by certification requirements. Those will be somewhere between small aircraft and helicopters with some eVTOL specifics. If it gets certified those bases are covered. Privacy: Regulated airspace is your friend, plis why wait for one those if you can have your own drone for the price of one Lilium ticket. Crime: Regulations also cover airport operations, so that base will be covered as well. For me the question is not if those aircraft are goong to fly (they will if it os technically possible and people fund development), but rather whether there is an actual market for those big enough to make the manufactirers and operators viable businesses. The last qiestion is hard (IMHO impossible) to answer without getting them to market first.

sokoloff 4y ago
There are certification requirements for both the aircraft and Ops Spec approvals for Part 135 (on-demand charter) operations. I can see that these would be certified to fly (and thus eligible for Part 91 (private) operations) far more easily than the more stringent requirements for Part 135 charter operations. The FAA thinking is that you have greater understanding as a passenger on a Part 91 operation and are better able to judge the risk yourself, whereas a Part 135 (charter) or Part 121 (scheduled airline) operation, the public cannot effectively judge the safety of the operation so the FAA holds them to a higher standard. Single engine Part 135 is possible, but there's a large amount of focus on redundancy: https://www.aviationconsumer.com/industry-news/single-engine-135/ https://www.aviationconsumer.com/industry-news/single-engine...

sokoloff 4y ago

These seem to compete more in the helicopter realm than the airliner realm. That's likely to be true of the relative level of safety of this vs a helo vs an airliner. (I've sometimes quipped that helicopters are one of the primary predators of billionaires.) While the stated/projected costs (which I doubt will be achievable), these would compete very favorably against a helicopter on a cost basis. Without the ability to auto-rotate (or a functional equivalent level of safety system), there's no way I'm getting in one nor recommending my family get in one [and I'm perfectly happy flying my family in single engine piston aircraft at night].

lambda 4y ago
eVTOL have to be designed to the same safety standards as other aircraft; and in fact, they will be held to slightly higher design safety standards due to their novelty, required to meet safety standards that otherwise only apply to larger transport category aircraft. You are right, eVTOL cannot autorotate, but electric motors can be far more reliable than internal combustion engines, with many fewer failure modes. Additionally, they are much lighter, and so you can have much greater redundancy. There is considerable redundancy in the lift motors on these aircraft, so one or in many cases more than one lift motor can fail while still providing safe and controllable flight. The exact level of redundancy needed is verified via probabilistic risk analysis, considering failure probabilities of different components, and as mentioned the target failure rate will be lower for these than for equivalent sized conventional aircraft due to their novelty. While there's still a lot of design and development work to do, I'd be very surprised if these didn't end up much more reliable and less prone to failure than helicopters and single engine airplanes. Note: I work for one of these startups, so I may be a bit biased, but I also have insight into the design process and safety and redundancy of systems are absolutely a top concern.
- lambda 4y ago
  Oh, I should also say, for a helicopter autorotation is only particularly helpful if you have enough forward airspeed or height to initiate it. Helicopters come with an HV diagram indicating safe flight envelope, such that autoration could be initiated in case of an engine failure, or you are low enough for a crash to be survivable if you do not have enough height or airspeed for autoration. https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velo... In an eVTOL, if you have enough height or velocity, you should be able to glide on the wing. So you'll be wanting to keep yourself in the appropriate region of the HV curve, and your emergency engine out procedure will be much more like a conventional fixed wing aircraft, rather than a helicopter.

lambda 4y ago

I work for one of these startups, Beta. We are focusing on a slightly different market than the other entrants; we're focusing initially on cargo rather than passenger transit. One initial customer is United Therapeutics, for transporting organ transplants and artificial organs to hospitals. Another is UPS, for getting air freight from airports to distribution centers; cutting out the truck trip can save a ton of time there. We are also making a passenger variant, but since the regulatory and NIMBY concerns for the passenger air taxi market present a lot of risk, we're not betting solely on that market like a lot of the other companies are. This helps with a lot of the concerns raised in this thread. In fact, another one that I'm not sure has been brought up is vertiport design and siting concerns; right now standards on vertiports are still a work in progress, and there are questions about whether it will be feasible to get them installed, because even with vertical takeoff and landing you generally need to keep approach angles of about 15° clear, which means once a vertiport is installed you need to limit the heights of any surrounding buildings to keep the approach clear. To address a few of your other concerns: we're located in northern Vermont, we know cold weather. Actually, for our use case hot weather tends to be more of a concern; batteries and motors heat up when used, especially in the very high power vertical lift phase, so our limitations there tend to be thermal and cold air provides better cooling. Our charging stations also include air for cooling and warming the batteries; so you should be able to avoid the issues with batteries being cold on startup with our air system. All aircraft have limitations on weather that they can be flown in; crosswind limits for takeoff and landing, etc. As very lightweight aircraft, with high lift/drag, these will be somewhat lower than the limits for your big jumbo jets, but will be high enough to be useful in a lot of weather. All aircraft have requirements for design and testing for HIRF (high intensity radiated field/lightning), so these will all be certified to the same standard there. Aircraft can optionally be certified for flight into known icing conditions (FIKI); I believe our plan is to have the capability, but as an optional add on, as it requires a number of heating elements which add weight and complexity. But overall, the weather concerns shouldn't be too much different than for other small aircraft. As far as safety goes, that's obviously a concern in any aircraft. One advantage of electric aircraft is that electric propulsion systems are far mechanically simpler, with far fewer moving and wearing parts. The only real wear item of concern are the main bearings on the motors, and the landing gear. So maintenance intervals can be much longer than with ICE aircraft, and I expect reliability to be considerably higher. Additionally, electric motors can be much smaller and lighter, and thus can be made redundant. Each propeller on our aircraft will be driven by multiple independent motors (probably can't say the exact configuration at the moment), so that motor failures can be tolerated without catastrophic consequences.

willyt 4y ago

Safety can be solved with a parachute that lands the whole aircraft in the event of a catastrophic failure. These are already fitted to high end GA aircraft like Cirrus.