3 ms·

I've held the opinion that we shouldn't be using multirotors but VTOLs when it comes to aerial deliveries. The multirotors are extremely energy inefficient, hav

I've held the opinion that we shouldn't be using multirotors but VTOLs when it comes to aerial deliveries. The multirotors are extremely energy inefficient, have very low MTBF, short-range and very low payload cap. On the other hand designing safe reliable VTOL is hard but solvable problem when thrown enough resources because you can draw a lot from existing aviation tech. However, Amazon has gone through quadrotors to VTOL and then they switched back to multirotor again, surprisingly. Unfortunately, most of the delivery vehicles are being built by relatively small limited resources startup-like groups. While multirotors are very easy to build, they have an enormous number of problems. I think if there was a well-funded group of 500 or so engineers working over ~5 years, there is a decent chance we can have safe reliable commercial-grade VTOL for autonomous point-to-point deliveries that can be adopted as standard. Unfortunately, this is a big capex project.

kortex 7y ago
Google has been experimenting with tailsitters, which I think is a no-brainer. Zipline is, imho, the real out of the box thinker. Catapault launch plus the snag line is Short takeoff, effectively-vertical landing, main downside is you need ground gear to land without damage. Main upside is weight savings for peak power (takeoff) is reduced, landing gear gone, and your engineering space is shrunk to solely the problem of steady state flight. I foresee the paradigm of winged mothership for last-hundred-mile, plus n-rotor drones for air-to-land leg of delivery.
- walrus01 7y ago
  Zipline's system is a much lower cost, light weight implementation of what InSitu (now a Boeing subsidiary since they were acquired) designed for the defense market, for their Scaneagle. They were by no means the first to launch or recover a fixed wing drone in that manner. As you point out it provides a lot of advantages in not needing to carry the extra weight for a VTOL, no landing gear, extra energy boost on launch. It's very close to the optimal energy usage in watts for motor, per size of craft, that can be achieved right now. The other advantage of using a single motor fixed wing craft is ability to use lithium ion batteries which are relatively higher Wh/kg density. These are not as capable of instantaneous high amps as lithium polymer are. The best commodity, commercially available lithium ion batteries are in the range of 210 to 248Wh/kg right now. The best lithium polymer batteries are about 178Wh/kg. FPV hobbyist fliers who build fixed wing and flying-wing craft use lithium ion for longer range. https://www.google.com/search?q=insitu+scaneagle&client=ubuntu&hs=uvY&channel=fs&source=lnms&tbm=isch&sa=X&ved=0ahUKEwizuM3nqu3jAhVLrZ4KHZQVDnoQ_AUIESgB&biw=1329&bih=1011 https://www.google.com/search?q=insitu+scaneagle&client=ubun...
- wereHamster 7y ago
  Zipline only works if you have a single base where you launch from land at. If you need to land at the customers site then you need VTOL capability.
  - joncrane 7y ago
    I think the idea is that the full-payload drone is launched via catapult, and the takeoff from the customer's site is without payload, allowing for lower power.
- jcims 7y ago
  Yeah I've been thinking same, possibly a UAV dirigible for the mothership. That would be cool.
walrus01 7y ago
Due to the very low energy storage density in Wh/kg for li-ion and li-po type batteries, VTOLs are the inevitable design decision a lot of companies are arriving at. For a big filming octo, capability to stay in the air for 45, 60 or 90 minutes is not essential and it doesn't need to travel far. If you look at the pilot projets for drone delivery in Canberra, it's all VTOLs. https://www.google.com/search?q=canberra+drone+delivery&client=ubuntu&hs=8pY&channel=fs&source=lnms&tbm=vid&sa=X&ved=0ahUKEwjj2di8qe3jAhWBv54KHevHCNoQ_AUIFCgE&biw=1329&bih=1011 https://www.google.com/search?q=canberra+drone+delivery&clie... The instantaneous watts required for forward flight with wings at a reasonable speed are much lower than the watts required for the same weight of craft, same general dimensions, same speed, forward flight with four, six or eight rotors.

kortex 7y ago

Google has been experimenting with tailsitters, which I think is a no-brainer. Zipline is, imho, the real out of the box thinker. Catapault launch plus the snag line is Short takeoff, effectively-vertical landing, main downside is you need ground gear to land without damage. Main upside is weight savings for peak power (takeoff) is reduced, landing gear gone, and your engineering space is shrunk to solely the problem of steady state flight. I foresee the paradigm of winged mothership for last-hundred-mile, plus n-rotor drones for air-to-land leg of delivery.

walrus01 7y ago
Zipline's system is a much lower cost, light weight implementation of what InSitu (now a Boeing subsidiary since they were acquired) designed for the defense market, for their Scaneagle. They were by no means the first to launch or recover a fixed wing drone in that manner. As you point out it provides a lot of advantages in not needing to carry the extra weight for a VTOL, no landing gear, extra energy boost on launch. It's very close to the optimal energy usage in watts for motor, per size of craft, that can be achieved right now. The other advantage of using a single motor fixed wing craft is ability to use lithium ion batteries which are relatively higher Wh/kg density. These are not as capable of instantaneous high amps as lithium polymer are. The best commodity, commercially available lithium ion batteries are in the range of 210 to 248Wh/kg right now. The best lithium polymer batteries are about 178Wh/kg. FPV hobbyist fliers who build fixed wing and flying-wing craft use lithium ion for longer range. https://www.google.com/search?q=insitu+scaneagle&client=ubuntu&hs=uvY&channel=fs&source=lnms&tbm=isch&sa=X&ved=0ahUKEwizuM3nqu3jAhVLrZ4KHZQVDnoQ_AUIESgB&biw=1329&bih=1011 https://www.google.com/search?q=insitu+scaneagle&client=ubun...
wereHamster 7y ago
Zipline only works if you have a single base where you launch from land at. If you need to land at the customers site then you need VTOL capability.
- joncrane 7y ago
  I think the idea is that the full-payload drone is launched via catapult, and the takeoff from the customer's site is without payload, allowing for lower power.
jcims 7y ago
Yeah I've been thinking same, possibly a UAV dirigible for the mothership. That would be cool.

walrus01 7y ago

Due to the very low energy storage density in Wh/kg for li-ion and li-po type batteries, VTOLs are the inevitable design decision a lot of companies are arriving at. For a big filming octo, capability to stay in the air for 45, 60 or 90 minutes is not essential and it doesn't need to travel far. If you look at the pilot projets for drone delivery in Canberra, it's all VTOLs. https://www.google.com/search?q=canberra+drone+delivery&client=ubuntu&hs=8pY&channel=fs&source=lnms&tbm=vid&sa=X&ved=0ahUKEwjj2di8qe3jAhWBv54KHevHCNoQ_AUIFCgE&biw=1329&bih=1011 https://www.google.com/search?q=canberra+drone+delivery&clie... The instantaneous watts required for forward flight with wings at a reasonable speed are much lower than the watts required for the same weight of craft, same general dimensions, same speed, forward flight with four, six or eight rotors.