Personal Aerial Vehicle (PAV) to take your commute into the third dimension

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Terrh

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Nov 12, 2016
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73
Location
Windsor, ON, Canada / Detroit, MI, USA.
I think that my approach to solving this problem would be to have two separate vehicles. It must be a lot easier to design a plane that can carry a small, 1000lb car than make a car that can fly or an airplane with road manners.

A 1000lb car, or room for a pair of motorcycles, sounds easy enough to design to me.
 

Kingfisher

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Aug 14, 2013
Messages
448
Location
Perth, WA, Australia
PAV commuter?

Been there, done that 50 years ago, it works: https://en.wikipedia.org/wiki/Canadair_CL-84

It works: "Despite the fact that the CL-84 was very successful in the experimental and operational trials carried out between 1972 and 1974, no production contracts resulted."

It works: "There were two main reasons for the technical success of the CL-84 design. Aerodynamic considerations were given a very high priority, and the controlling of power was kept as simple and direct as possible. The propeller disks extended slightly beyond the wingtips, so the whole of the wing (except for the portion above the fuselage) was immersed in the propeller slipstream. This, together with full-span leading edge and trailing edge flaps which were programmed with wing tilt angle, ensured that the wing was never stalled. Trim changes were minimized by programmed tilting of the tailplane. All programming was based on extensive testing in the wind tunnel and on an outdoor mobile test rig. The power of both engines was controlled by a single "power lever" in all flight regimes. To provide crisp thrust control during hover, movement of the power lever caused a direct adjustment of blade angle, analogous to the collective pitch control of a helicopter, with the propeller cpu governor making a follow-up adjustment of blade angle to maintain the selected rpm. The direct adjustment of blade angle was faded out automatically as the blade angle increased with increasing forward speed."

It works: "The CL-84-1 performed flawlessly, demonstrating versatility in a wide range of onboard roles, including troop deployment, radar surveillance and anti-submarine warfare. It could perform wing transition from zero airspeed and accelerate to 100 knots in 8 seconds."

It works: "In the face of gale storm conditions, the "84" performed magnificently in tasks such as ferrying troops and "blind-flight." Phase 3 and 4 trials proceeded immediately after, but, despite rave reviews from over 40 pilots, the CL-84-1 did not land any production contracts."

Now... take that well proven and demonstrated viable aircraft configuration and control model, and use modern electric motors to eliminate the majority of power system complexity. One main configuration and control computer (with two backup systems) should be able to manage all of the previously complicated mechanical control linkages, mixers, and modulated hydraulic systems. Today these computers would be the size of an iPad.

Make it smaller and lighter than the military prototype, use modern materials where advantageous.

Having a more efficient forward flight mode will extend the range and speed of the "cruise" portion of your commute far better than a PAV helicopter or lift-fan-only design. The Canadair prototype was a 300 MPH aircraft; scaling back the cruise speed requirement to 125 MPH would permit large reductions in required power, battery and structure weight, complexity, etc.

Making a thicker, slightly larger, and higher lift wing (taking advantage of the reduced speed requirement) will also create the ability to have some amount of power-off glide. Not great by any means, but a lot better than some of the tinfoil hat ideas. Using the computers to their best advantage, and using a rapid wing tilt emergency mode, in a total power failure you might be able to glide fast and steeply downwards, putting energy into the rotor/propellers, tilt the wing upwards at the bottom of the glide, and use the kinetic energy in the rotor/propellers to have five or eight seconds of vertical landing capability just like the last few seconds of a helo autorotation.

OK, let me have it with both barrels... flame away :)
Hello VB,
I really apologize for not responding to this great post of yours. I have a weird thing with the forums, sometimes I get all fired up and post stuff, and then I don't even look at the response.
There are some similar old designs to what I have posted, one with tilting wings and 4 rotors, the other only 4 tilting rotors and fixed wings. I have summarised them in a little patent paper regarding my proposal, which I've submitted as a provisional application, just for the record. The CL-84 was not one of them, and I had never heard of it. It is interesting it was so successful in its mission, and the failures where all mechanical. Same was true for the other designs, regarding the failures, but not as much success. The "84" seems to have gone a fair distance on the way to prove itself.
Like you said, the electric motors with computer aided control should reduce this failure potential. All your other comments I agree with, too, although not sure about the autorotation, one would need variable pitch for sure. Maybe it's a must have anyway to extend the speed envelope, but not on first prototype. I have had my main parts 3D printed to make a model about 800mm wingspan. I realise full scale requirements are much tougher, just want to have some fun. But by the slow pace I work at, others will pass me by....
 

TFF

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Joined
Apr 28, 2010
Messages
13,054
Location
Memphis, TN
There is a company with a Robinson R-44 converted to electric. It can do about two traffic patterns to hover in the safe range of battery care. Any more and it would junk them. I don't think it can take a passenger.
 

Aesquire

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Jul 28, 2014
Messages
2,415
Location
Rochester, NY, USA
I say thee Nay! Nay!

That said, looks good.

Free wing is not a good idea here I think. You want control of wing position because of the dynamic range of airflow as the wings tilt. A free wing is a special case design like a Flea. Works fine in it's deliberate limited control scheme.

Aka. Don't cross the streams.

The ultimate flying car IMHO ( except for Thunderbirds Are Go ) was in the TV show "The Magician", starring Bill Bixby as a do-good who used magic tricks to help people. One season he was headquartered at The Magic Shop but others he flew around in a 727 with the rear stairs as a car ramp to disgorge his Corvette. Or was it one season with the plane? Whatever, it was functional.

Scaling that down is going to be tricky. Suzuki had a two seat car that might work, or you can go for the Smart mini car & death trap.

( rant on ego driven sales of stupidly expensive junk to idiots with raging blazing hatred towards German over engineering..... deleted ;) )
 

Victor Bravo

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Jul 30, 2014
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KWHP, Los Angeles CA, USA
As has been discussed on several of these threads, a homebuilt airpane the size of a Cessna Caravan, but configured with a rear ramp like a Skyvan or C-119 Boxcar could easily carry a purpose built two seat enclosed motorcycle. The road vehicle doesn't have to be side by side seating, thus allowing the airplane to be within reason width wise.

This is the Auster B.4, an airplane that is essentially a modified Taylorcraft with large clamshell doors to be used as an air ambulance.

b4_in_flight.jpg
 

Kingfisher

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Aug 14, 2013
Messages
448
Location
Perth, WA, Australia
I say thee Nay! Nay!

That said, looks good.

Free wing is not a good idea here I think. You want control of wing position because of the dynamic range of airflow as the wings tilt. A free wing is a special case design like a Flea. Works fine in it's deliberate limited control scheme.

Aka. Don't cross the streams.

The ultimate flying car IMHO ( except for Thunderbirds Are Go ) was in the TV show "The Magician", starring Bill Bixby as a do-good who used magic tricks to help people. One season he was headquartered at The Magic Shop but others he flew around in a 727 with the rear stairs as a car ramp to disgorge his Corvette. Or was it one season with the plane? Whatever, it was functional.

Scaling that down is going to be tricky. Suzuki had a two seat car that might work, or you can go for the Smart mini car & death trap.

( rant on ego driven sales of stupidly expensive junk to idiots with raging blazing hatred towards German over engineering..... deleted ;) )
So true that a lot things we take for granted were spawned by a writer of either book or film. The english speaking parts of the world seem to have bit more imagination and sense of humour in these things. Especially tv ads are way better than in Germany. All that Starwars airtraffic is so cool, and plausible if one had the machines to do it.
I guess some German things are overengineered, especially the upmarket stuff. Regarding the multicopter, though, I'm not even sure who invented it. When I was still poor/in school, I had tampered with the idea of steering a multiengined Rc plane, or helicopter, with its motors via the speed controls. The problem was I only had one motor, and it was so weak it couldn't even lift its own weight.
 

harrisonaero

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Oct 31, 2009
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565
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Coeur d'Alene, ID
Sheesh. The whole point of a flying car is that it can drive to an airport and then operate as an airplane with all the inherent aero advantages. If you want a VTOL don't bother with the car part- just land at your destination.

And while you're improving your design, you'll find that at the rotors get larger everything becomes more efficient.

(hint- invented in 1939 and is used very successfully all over the world today)
 

Victor Bravo

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KWHP, Los Angeles CA, USA
^^^^^^ +1 ^^^^^^^

Another thing in favor of an "airplane" flying car is that even the people who own FAA certified helicopters usually can't land at their destination. Either the city/county laws won't allow it, or the cops show up and cause problems because they got a "crash" 911 call, or the neighbors are upset, etc. The whole George Jetson rooftop platform thing is very very hard to achieve. If it were doable, there would be twenty thousand lawyers and surgeons and white collar crooks commuting to work every day in their A-Star, not just a small handful of really wealthy folks that do it now.

So if the multi-copters and Uber-Air Taxis and and all the other potentially viable VTOL personal transport stuff actually became available to the public at a reasonable cost... there is still this "societal barrier" that would be even harder to break than the technical/mechanical barriers.

As unfortunate as it is, I would guess that when the E-Volo is finally in the hands of the average Joe, they will be flying from airport to airport for a long time, until there is an infrastructure of urban STOL-Ports, or VTOL ports or helipads that are actually accessible and affordable to the general public.

In the meantime, it seems logical that the "airplane" flying cars and PAV's that are designed to operate at airports and then drive into town will be in daily use, and (again unfortunately) the PAV / VTOL owners will not be able to get the full benefit of that technology.

I hope I'm wrong. I hope that multi-copters and VTOL PAV's will be allowed to operate wherever they can fit. But logic tells me that (at least in America) our liability lawyers and risk-averse city managers will be terrified of the mult-copters landing in the city park or baseball field.
 

BBerson

Light Plane Philosopher
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Dec 16, 2007
Messages
13,253
Location
Port Townsend WA
Four wheels and two drive belts could be fitted to any R-22 and then drive it down the road to the local airport or heliport field and takeoff.
But who wants a two-seat (1.5 seat? with wheels) that costs $150 per hour to operate?
 

Riggerrob

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Sep 9, 2014
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1,448
Location
Canada
^^^^^^ +1 ^^^^^^^

Another thing in favor of an "airplane" flying car is that even the people who own FAA certified helicopters usually can't land at their destination. Either the city/county laws won't allow it, or the cops show up and cause problems because they got a "crash" 911 call, or the neighbors are upset, etc. The whole George Jetson rooftop platform thing is very very hard to achieve. If it were doable, there would be twenty thousand lawyers and surgeons and white collar crooks commuting to work every day in their A-Star, not just a small handful of really wealthy folks that do it now.
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Helicopter commuting is already popular in Brazil's larger cities because elites fear driving. They fear driving because of all the street crime, gang wars, car-jacking, kidnapping, etc.
Brazil has such huge wave disparities that the rich can land wherever they can afford to land, while city council ignores millions of poor people.
 

Riggerrob

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Sep 9, 2014
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Canada
Kingfisher's original sketch reminds me of a multi-copter patented in France during the 1950s. Try to picture a small car surmounted by the world's greatest roof-rack!
It had four rotors. The rear rotors folded forward to stow along the sides of the roof, while the forward rotors folded aft. The body was a typical, small European sedan that could be driven on surface streets.

Now the challenge is to update this old patent with modern horsepower and electronics.

For short-range commuting, wings are irrelevant.
 

Victor Bravo

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For short-range commuting, wings are irrelevant.
Define short range... three city blocks away? To go three blocks, yes you can use a rocket belt or a Harrier style vectored thrust turbine.

I'm pretty sure that wings (whether fixed or rotating) will start to become favorable quickly once you increase the commute distance above 4 or 5 miles.
 

BBerson

Light Plane Philosopher
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Port Townsend WA
Yeah. I don't think inner city air transport can happen. Gravity always wins. The futurists don't have an answer for total safety yet.
Might work to a boat dock with overwater flights.
 

Victor Bravo

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Inner City air transport may be different than a Personal Air Vehicle commuter. That huge Sikorsky in the video was definitely not a small personal transport!

BTW I got to fly on the Los Angeles Airways version of that once when I was a kid.

Here's the thing - Wings that are fixed on the fuselage, or wings that are always in a state of autorotation (gyroplane) are pretty reliable, likely to be reliable in a city environment. As long as you don't base the primary flightworthiness of the craft on Dilithium Crystals or Mollerium or the Jupiter Battery, you have a chance of achieving good enough reliability to operate in a city environment. That famous video of a gyroplane delivering mail on top of a NY skyscraper happened 80 years ago.

Keeping the legalities and the bureaucratic paperwork aside for a moment... a small 1 seat personal gyro with "jump" capability (and a decent pilot) could safely and reliably operate on and off the top of a city parking structure, using 50-60 year old aircraft technology and materials. No Secret Sauce. No alien battery technology. No 5000 RPM fan blades being turned by a bunch of 10,000 RPM engines. NO !(#*% COMPUTERS.
 

BBerson

Light Plane Philosopher
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Port Townsend WA
Almost no chance of getting an approved personal autogyro or helicopter landing area in a major city now.
Even a 5 pound drone can kill you. A person was injured in Seattle from a small drone.
 

Kingfisher

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Aug 14, 2013
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448
Location
Perth, WA, Australia
Here is an update to my project. Obviously Opener and Vahana have beaten me to it, but I got it to fly on a small scale. Still find the free wing interesting, but it is probably not necessary. At this point I think a wing that tilts with the engine as one unit and is fully immersed in the propeller slipstream is probably best.
[video]https://1drv.ms/v/s!AlOiWyKLXM2DgjFLUcRCYbGx66md[/video]
 

BrettG

New Member
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Jul 10, 2014
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Location
CA, USA
Here is an update to my project. Obviously Opener and Vahana have beaten me to it, but I got it to fly on a small scale. Still find the free wing interesting, but it is probably not necessary. At this point I think a wing that tilts with the engine as one unit and is fully immersed in the propeller slipstream is probably best.
[video]https://1drv.ms/v/s!AlOiWyKLXM2DgjFLUcRCYbGx66md[/video]
Howdy Kingfisher,

Interesting design, thanks for sharing the video! I look forward to more!

I'm with a company that's been in this space since before those two you mentioned. I've flown many configs, including things like yours, though with direct control of the wing tilt (though we moved away from tilt wings). You will probably not find a linear actuator that is light enough and fast enough for good tilt control, and most servos are not precise enough to hold accurate position of such a powerful effector. The best results we've had are with the Dynamixel servos by ROBOTIS. I've used the MX-106R extensively, and a few of their smaller ones, these work great and handle lots of abuse: http://www.robotis.us
 

Kingfisher

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Aug 14, 2013
Messages
448
Location
Perth, WA, Australia
Howdy Kingfisher,

Interesting design, thanks for sharing the video! I look forward to more!

I'm with a company that's been in this space since before those two you mentioned. I've flown many configs, including things like yours, though with direct control of the wing tilt (though we moved away from tilt wings). You will probably not find a linear actuator that is light enough and fast enough for good tilt control, and most servos are not precise enough to hold accurate position of such a powerful effector. The best results we've had are with the Dynamixel servos by ROBOTIS. I've used the MX-106R extensively, and a few of their smaller ones, these work great and handle lots of abuse: http://www.robotis.us
Hi BrettG,

Thanks for sharing your experience. Makes me wonder what company it is you're with, I think I have an idea. The robotis servos will come in handy if I ever get to built something bigger, I think they are too heavy for my small scale, but I haven't looked at all the options yet. Price is a factor....I've just received some more powerful conventional servos for this model, I'll give that a shot next. Attached is short paper I wrote with regards to control strategy and possible advantages and disadvantages of the idea. I haven't included excessive control forces and precision of actuators, but share your concerns there.
 

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Dusan

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Sep 15, 2014
Messages
72
Location
Canada
Hi Kingfisher, great for sharing your work!

I think the biggest problem for VTOL aircraft design is the disparity in power between hovering and cruising. This VTOL conundrum is somewhat alleviated by the high efficiency of electric propulsion, but the lift in hover still needs to be increased without consuming much more power. Just tilting the rotors will not do; e.g. for a cruise L/D of 10, thrust needs to be increased 10 times for VTOL operation, and power rises even more, exponentially. Designing the aircraft for efficient VTOL operation, low disk loading is needed, leading invariably to large rotor disk area, which is detrimental to efficient cruise operation. Having the wings in the rotor's slipstream they are just dead weight, even worse they consume energy as boundary layer friction. Some gain can be achieved by putting them in front of the rotors, as here: http://aliptera.com/development.html#Lip Wing
 
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