From the pictures of UrbanAero flying car: https://www.urbanaero.com/cityhawk, I can see that can achieve VTOL using the two propeller in front of and in the back of the passenger compartments. However, I am not sure how does it move forward. The propellers don't look like they would rotate, and there are exhaust ports in the back of the vehicle that suggest air would come out and push the car forward. However, this requires an impeller, not a propeller. Could anyone explain this to me? Thank you very much!
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2$\begingroup$ I suppose the same way as a helicopter—by pitching down a bit. $\endgroup$– Jan HudecCommented Nov 19, 2021 at 19:17
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5$\begingroup$ Looks like vaporware... not clear that there are any real examples of this concept flying at all, neither forward, backward, or in any direction. $\endgroup$– Ralph J ♦Commented Nov 19, 2021 at 23:39
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$\begingroup$ The airplane as such was vapourware from 400 BC to 1903 AD. $\endgroup$– boglCommented Nov 20, 2021 at 15:15
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5$\begingroup$ @bogl That's true, and as such it received correspondingly little attention on internet message boards during that same timeframe! 😄 $\endgroup$– Ralph J ♦Commented Nov 20, 2021 at 16:18
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2$\begingroup$ @bogl: And a good many things that were vaporware in that time period still are, many of them for good reasons :-) $\endgroup$– jamesqfCommented Nov 20, 2021 at 18:03
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3 Answers
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It would fly forward the same way a quadcopter does: have the aft motor controller increase current, thereby increasing aft fan lift, creating a pitching moment downward and moving the fan arcs out of planarity with the horizontal, thereby creating a thrust component. One would have to develop an anti-torque system to counter the increased torque of the rear fan, but that’s not unrealistic.
Now that being said, I agree with Ralph J’s analysis: That thing is nothing more than idiotic vaporware by some pie in the sky software geek or actual con artists looking to part you from your money. Flying cars, moisture farming, solar roadways, etc. are apparently very luring for well meaning but scientifically illiterate people who want real life to be like The Jetsons. Plenty a con man can easily take a pigeon like that for a ride…
answered Nov 20, 2021 at 15:06
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$\begingroup$ Yes, 4 rotors may be better! A ducted scaled up quad might work. $\endgroup$ Commented Nov 20, 2021 at 15:18
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2$\begingroup$ it is propelled forward by two things in combination: 1) money and 2) gullibility. $\endgroup$ Commented Nov 20, 2021 at 20:34
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$\begingroup$ @nielsnielsen: Gullibility is bottomless, it's ecstatic. $\endgroup$– minsCommented Nov 20, 2021 at 23:55
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The Urban-Air question, with provided downlink, does seem to show a viable twin rotor design that may provide a more stable flying platform than that experienced with the Avro VZ-9 Avrocar concept from 1959-1961.
Some fairly serious research was done by Avro for use as a modern US Army and Air Force transport vehicle. Although strongly contributing to "flying saucer" legend, excessive gyroscopic effects (before the age of computers) doomed the design.
It is entirely possible 2 rotors may make it much easier to fly.
The Avrocar used vectored thrust for horizontal motion. For lift, the Urbanaero is essentially a ducted Chinook helicopter. At low airspeeds, not a great deal of thrust would be needed to manuever this "air taxi". The advertisement claims variable pitch rotors.
answered Nov 20, 2021 at 14:10
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I can indeed see the two large propeller fans inside the craft, with guiding vanes to direct the exit flow left/right (cannot detect any fwd/aft adjustment). The propellers provide take-off lift, after TO the craft can be tilted forward in order to introduce a forward component of the lift vector, indeed like helicopters do. Temporarily more lift from the aft rotor, point the exhaust vanes slightly sideways to compensate for its increased torque.
Flying with the craft seems to be theoretically possible, but there are serious questions about its safety.
- There is no fixed wing, and therefore it cannot glide back to earth upon a power failure. This would have to take place via autorotation, like in a helicopter, but because of the propeller exhaust vane arrangement autorotation airflow would always be vertical through the rotors. Which is not recommended!.
- Both the rotors are required to always be operational, otherwise the balance would be distorted, resulting in a crash. Are they mechanically coupled to ensure this?
- The power source is electric motors power by hydrogen. This is not mature technology even in electric cars, and are those hydrogen pressure tanks in the picture below? Under high pressure just behind the passengers?
Yeah a flying car might one day be feasible. Even an electrically powered flying car could be done - when all the technology is matured out by experience, since flying takes place at higher altitudes than driving.
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2$\begingroup$ In the bottom graphic, interesting choice of tense that they use: "... is the world's first H2 powered vtol." Their little dream is nothing but a plan right now; to say "will be" would express confidence in the future, although "is hoped to be" would perhaps be more accurate. Upvoted for comments about not-yet-mature technologies. $\endgroup$– Ralph J ♦Commented Nov 21, 2021 at 13:15
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1$\begingroup$ @RalphJ: I also noted their first "design" was with classic batteries, but it was challenged, so they switched to fuel cells. Currently their "prototype" flies with a classic fuel engine, to test the fuselage and the control panel electronics. $\endgroup$– minsCommented Nov 21, 2021 at 13:38