Comment by bufferoverflow 6 days ago
It's an impressive achievement for an amateur.
He has separate motors for vertical and horizontal flights, which simplifies the design, but creates a rather bad inefficiency, the vertical motors create lots of drag during the horizontal flight.
Maybe it's not a big deal, I'm not sure. Making motors rotate would add weight for sure, thus reducing the range.
Very similar design already used by Wing. I'm guessing they did a fair bit of analysis and modeling of the cost, range, complexity, safety, etc. etc. tradeoffs before settling on what they're using currently.
https://en.wikipedia.org/wiki/Wing_Aviation#/media/File:Wing...
Two impressive things about Wing's design are 1) load paths are designed to break the airframe in controlled ways 2) the 4 blade props have alternating shorter and longer blades for quieter aeroacoustics
Adam Savage did a video tour of their factory recently, worth a watch
> Adam Savage did a video tour of their factory recently, worth a watch
Thanks! https://www.youtube.com/watch?v=_BXm6dTHvY0
I'm a big Waymo and Wing fan, but hadn't seen that.
It's great, check out the Slo Mo guys video from that same tour for the prop smoke vortex https://www.youtube.com/watch?v=5yaAFLpLmVg
Adding a tiltrotor mechanism is surely not worth the added complexity and weight, in this case. You're right though on the added weight and drag from having separate motors and props.
There are lots of DIY variations on the theme -- here's one: https://hackaday.com/2022/08/22/optimising-a-rc-tilt-rotor-v...
Shameless plug: https://aliptera.com/
Tilt-rotor on all 4 motors with an extra twist: the wing shape adds to the lift in vertical mode, so you can use smaller motors, so they're more efficient even in horizontal mode.
And the weight (and drag) penalty is ~5% given the actuators and subassemblies for tilting don't come for free either.
This is also the most the penalty will ever be as electric motors continue increasing in specific power, and quite rapidly this century so far.
It's actually not a terrible inefficiency.
With this config, the cruise motors and prop are optimally sized for cruise - which gives non trivial gains to both eta for propulsive motor efficiency and prop efficiency.
Vs a tiltrotor/wing/body in which the cruise motor has to do double duty as lifting motors. Given it takes anywhere from ~4-7x more power to hover (depending on disc loading) than to cruise, you can see how the motors are not in an optimal throttle/rpm band in this case. Archer's CTO Munoz has actually said this publicly.