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I think most forms of assisted takeoff technology would reduce electrical power requirements for takeoff, but not put much of a dent in the climb power (unless

by mliben 6y ago

I think most forms of assisted takeoff technology would reduce electrical power requirements for takeoff, but not put much of a dent in the climb power (unless you can catapult/ JATO all the way up to cruising altitude, which would be challenging). Since climb power is still significantly higher than cruise power, and is effectively thermal steady state for these components (10-20min), it would still drive the propulsion system sizing.

hbrav 6y ago
You could have another aircraft tow you, like gliders sometimes do. Doesn't seem terribly practical though.
- mliben 6y ago
  Not exactly what Talyn Air is doing, but along the same lines- separating out the "lift/climb" vehicle from the "cruise" vehicle. It can actually be a very compelling design!
- omgwtfbyobbq 6y ago
  That could be a great use case for lighter/smaller electric motors, since a tow plane could take off, assist with takeoff, turn around and land, charge, and repeat. The tow plane wouldn't need as large of a battery pack, but having good power to weight for towing other plants to whatever altitude is very important.
  - mchusma 6y ago
    I feel like this is something that drones/100% automated ops can really help with. Power satellites (basically giant solar arrays transmitting power) are also interesting (https://www.geekwire.com/2020/space-force-will-test-solar-power-transmission-x-37b-space-planes-next-mystery-flight/ https://www.geekwire.com/2020/space-force-will-test-solar-po...). We could have these complex automated systems to make electric aircraft much more viable, which is cool in theory.
    - outworlder 6y ago
      Power satellites are interesting. But here's the thing: For most aircraft (except some gliders), covering them fully with solar panels is not even close to the power they need in cruise, correct? So a power satellite would have to generate _at least_ the same W/m2 as the sun (around 1.4kw/m2( just to break even with a solar panel, but most likely much, much more, by orders of magnitude. For a 747, I've seen figures from 90 MW to almost 200MW. If the receivers were at the wings only, that would be almost 6MW per square meter if you take the lower figure. For a target as small as a plane, this would look like an energy weapon from science fiction. Even something like this would not cut it: https://en.wikipedia.org/wiki/MIRACL https://en.wikipedia.org/wiki/MIRACL For general aircraft the numbers look better. Then again, they are much smaller. I can't wait for power satellites to be deployed, but they will mostly be servicing ground stations.
throwawayboise 6y ago
You still need enough reserve power at the end of a flight to do a rejected landing/go around, or you won't get certified. If you are relying on some kind of catapult, rail gun, or rocket assist to take off, not sure how that happens.
- sokoloff 6y ago
  An early rejected landing still requires less power than a static takeoff, so you could get by with a mix of craft and assistive power.

by mliben 6y ago

hbrav 6y ago

You could have another aircraft tow you, like gliders sometimes do. Doesn't seem terribly practical though.

mliben 6y ago
Not exactly what Talyn Air is doing, but along the same lines- separating out the "lift/climb" vehicle from the "cruise" vehicle. It can actually be a very compelling design!
omgwtfbyobbq 6y ago
That could be a great use case for lighter/smaller electric motors, since a tow plane could take off, assist with takeoff, turn around and land, charge, and repeat. The tow plane wouldn't need as large of a battery pack, but having good power to weight for towing other plants to whatever altitude is very important.
- mchusma 6y ago
  I feel like this is something that drones/100% automated ops can really help with. Power satellites (basically giant solar arrays transmitting power) are also interesting (https://www.geekwire.com/2020/space-force-will-test-solar-power-transmission-x-37b-space-planes-next-mystery-flight/ https://www.geekwire.com/2020/space-force-will-test-solar-po...). We could have these complex automated systems to make electric aircraft much more viable, which is cool in theory.
  - outworlder 6y ago
    Power satellites are interesting. But here's the thing: For most aircraft (except some gliders), covering them fully with solar panels is not even close to the power they need in cruise, correct? So a power satellite would have to generate _at least_ the same W/m2 as the sun (around 1.4kw/m2( just to break even with a solar panel, but most likely much, much more, by orders of magnitude. For a 747, I've seen figures from 90 MW to almost 200MW. If the receivers were at the wings only, that would be almost 6MW per square meter if you take the lower figure. For a target as small as a plane, this would look like an energy weapon from science fiction. Even something like this would not cut it: https://en.wikipedia.org/wiki/MIRACL https://en.wikipedia.org/wiki/MIRACL For general aircraft the numbers look better. Then again, they are much smaller. I can't wait for power satellites to be deployed, but they will mostly be servicing ground stations.

throwawayboise 6y ago

You still need enough reserve power at the end of a flight to do a rejected landing/go around, or you won't get certified. If you are relying on some kind of catapult, rail gun, or rocket assist to take off, not sure how that happens.

sokoloff 6y ago
An early rejected landing still requires less power than a static takeoff, so you could get by with a mix of craft and assistive power.