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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 p

by 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.

sokoloff 4y ago
> crosswind limits for takeoff and landing Most aircraft have a “maximum demonstrated crosswind capability” which is a required test flight item but is not a limitation. It has to be demonstrated during flight testing to a figure of not less than 20% of Vso, but once that’s hit, they don’t have to find a greater crosswind to determine an actual limit.
- lambda 4y ago
  You're right. The maximum demonstrated crosswind velocity isn't a limit, but more of a guideline, based on what was tested for. However, many aircraft do that testing to a higher level than is required. For instance, for a Cessna 172, 20% of Vso would be 8.2 knots, but it has a maximum demonstrated crosswind velocity of 15 knots. Anyhow, all I'm saying is that at least for our aircraft, it looks likely that the maximum demonstrated crosswind velocity will be on the low side; at least the mandated limit based on Vso, possibly a few knots higher, but like most small aircraft, much much lower than what you have for big jets.
  - sokoloff 4y ago
    Pilots will care more about the aircraft’s capabilities than the demonstrated crosswind limits. My A36 was demonstrated to only 15knots IIRC, but easily handles a 25 knot direct crosswind. Whether Beech test flew it to 11, 15, or 20 knots I wouldn’t care the least bit about. (In VTOL mode, could you wheel the aircraft into the prevailing wind for takeoff and/or land it pointed into the wind to reduce crosswind effects? [I’m a fixed wing guy with I think only 0.7 dual received in a helo.])
    - lambda 4y ago
      Yes, in VTOL mode you are generally going to want to land into the wind or wheel the aircraft into the wind for takeoff. I think that would probably be possible. But we are also concerned with CTOL performance; in order to add more flexibility, CTOL performance is something that we are focusing on heavily, as if a runway is available you can do a takeoff and/or landing with lower energy use and thus get more range, so we're designing to be able to takoff and land either CTOL or VTOL. For example, one of our use cases is cargo, such as UPS getting packages from an airplane at the airport, to its distribution center. At an airport, you have a runway available for takeoff, so you might do a CTOL takeoff, and then a VTOL landing at the distribution center, and vice versa for the return trip. And what I'm saying is that our aircraft, at least, won't have crosswind capabilities that are terribly high when doing CTOL takeoff and landing. It's pretty light and floaty and has a strong weathervaning tendency, and control surface sizes are kept limited in order to save weight and drag. It will be able to handle the minimum and maybe a bit more, but I wouldn't expect it to do well significantly above what the demonstrated crosswind velocity is. Ours is designed more as a glider that happens to have electric propulsion and lift capabilities, rather than a conventional powered aircraft, in order to be able to eke more range out of our batteries and provide a greater safety margin in the event of loss of propulsion power, but there are some tradeoffs to that design. Also, I should say that I'm a software guy, this is my first aviation related job, and I only have about 2 hours in my logbook for dual received, and our certified design is not finalized and we are still doing some trades on things like control surface sizes, so anything I say here might be wrong now or in the future. But right now, we have a fairly limited crosswind envelope.

by lambda 4y ago

sokoloff 4y ago

> crosswind limits for takeoff and landing Most aircraft have a “maximum demonstrated crosswind capability” which is a required test flight item but is not a limitation. It has to be demonstrated during flight testing to a figure of not less than 20% of Vso, but once that’s hit, they don’t have to find a greater crosswind to determine an actual limit.

lambda 4y ago
You're right. The maximum demonstrated crosswind velocity isn't a limit, but more of a guideline, based on what was tested for. However, many aircraft do that testing to a higher level than is required. For instance, for a Cessna 172, 20% of Vso would be 8.2 knots, but it has a maximum demonstrated crosswind velocity of 15 knots. Anyhow, all I'm saying is that at least for our aircraft, it looks likely that the maximum demonstrated crosswind velocity will be on the low side; at least the mandated limit based on Vso, possibly a few knots higher, but like most small aircraft, much much lower than what you have for big jets.
- sokoloff 4y ago
  Pilots will care more about the aircraft’s capabilities than the demonstrated crosswind limits. My A36 was demonstrated to only 15knots IIRC, but easily handles a 25 knot direct crosswind. Whether Beech test flew it to 11, 15, or 20 knots I wouldn’t care the least bit about. (In VTOL mode, could you wheel the aircraft into the prevailing wind for takeoff and/or land it pointed into the wind to reduce crosswind effects? [I’m a fixed wing guy with I think only 0.7 dual received in a helo.])
  - lambda 4y ago
    Yes, in VTOL mode you are generally going to want to land into the wind or wheel the aircraft into the wind for takeoff. I think that would probably be possible. But we are also concerned with CTOL performance; in order to add more flexibility, CTOL performance is something that we are focusing on heavily, as if a runway is available you can do a takeoff and/or landing with lower energy use and thus get more range, so we're designing to be able to takoff and land either CTOL or VTOL. For example, one of our use cases is cargo, such as UPS getting packages from an airplane at the airport, to its distribution center. At an airport, you have a runway available for takeoff, so you might do a CTOL takeoff, and then a VTOL landing at the distribution center, and vice versa for the return trip. And what I'm saying is that our aircraft, at least, won't have crosswind capabilities that are terribly high when doing CTOL takeoff and landing. It's pretty light and floaty and has a strong weathervaning tendency, and control surface sizes are kept limited in order to save weight and drag. It will be able to handle the minimum and maybe a bit more, but I wouldn't expect it to do well significantly above what the demonstrated crosswind velocity is. Ours is designed more as a glider that happens to have electric propulsion and lift capabilities, rather than a conventional powered aircraft, in order to be able to eke more range out of our batteries and provide a greater safety margin in the event of loss of propulsion power, but there are some tradeoffs to that design. Also, I should say that I'm a software guy, this is my first aviation related job, and I only have about 2 hours in my logbook for dual received, and our certified design is not finalized and we are still doing some trades on things like control surface sizes, so anything I say here might be wrong now or in the future. But right now, we have a fairly limited crosswind envelope.