The concept of a flying car will eventually succeed

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

Turd Ferguson

Well-Known Member
HBA Supporter
Joined
Mar 13, 2008
Messages
5,879
Location
Upper midwest in a house
It's estimated that ~300 different companies are designing/building some kind of flying car/VTOL aircraft for the upcoming revolution in travel. Giant drone versions are likely to be the winner. Checkout Homepage Volocopter
 

Dusan

Well-Known Member
Joined
Sep 15, 2014
Messages
193
Location
Canada
Giant drone versions are likely to be the winner.
I tend to disagree here. The low specific energy of current batteries are emphasising aerodynamic efficiency of the aircraft configuration. Lift per Drag ratio is the parameter that drives the cruise performance regardless of aircraft type. Multi-rotor configurations are worse hover performers than the classical tail-rotor helicopter configuration only because they tend to have higher disk loading, a consequence of simplified control and mechanical design. Edgewise rotors/propellers have anyway a poor Lift per Drag ratio. Conventional helicopters rarely achieve a L/D of 5, I'm not sure of multi-rotors, I haven't seen too many published L/D for them, but I assume they are worse than conventional helicopters - only considering drag interference between multiple rotors, correct me here if I'm wrong.

The 'dirtiest' fixed wing aircraft is still able to achieve a L/D of 10 - and this means it needs half the energy to achieve the same range or endurance vs an aircraft having L/D of 5, at similar weight, size and speeds.

This is the reason I believe the next "flying car" (I prefer personal aircraft) will actually have wings and able to transition to a more efficient wing-borne flying mode.

The technical 'battle' is not who has the best motor, or controller or even the highest specific energy battery system - but which configuration is able to achieve the best aerodynamic effectiveness in cruise and hover. The problem here - not solved yet, despite 70+ years of VTOL history - is that Disk Loading determines hover performance and Lift per Drag ratio determines cruise performance, and they are mutually exclusive. A high DL determines a low L/D and vice versa.
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
6,587
I tend to disagree here. The low specific energy of current batteries are emphasising aerodynamic efficiency of the aircraft configuration. Lift per Drag ratio is the parameter that drives the cruise performance regardless of aircraft type. Multi-rotor configurations are worse hover performers than the classical tail-rotor helicopter configuration only because they tend to have higher disk loading, a consequence of simplified control and mechanical design. Edgewise rotors/propellers have anyway a poor Lift per Drag ratio. Conventional helicopters rarely achieve a L/D of 5, I'm not sure of multi-rotors, I haven't seen too many published L/D for them, but I assume they are worse than conventional helicopters - only considering drag interference between multiple rotors, correct me here if I'm wrong.

The 'dirtiest' fixed wing aircraft is still able to achieve a L/D of 10 - and this means it needs half the energy to achieve the same range or endurance vs an aircraft having L/D of 5, at similar weight, size and speeds.

This is the reason I believe the next "flying car" (I prefer personal aircraft) will actually have wings and able to transition to a more efficient wing-borne flying mode.

The technical 'battle' is not who has the best motor, or controller or even the highest specific energy battery system - but which configuration is able to achieve the best aerodynamic effectiveness in cruise and hover. The problem here - not solved yet, despite 70+ years of VTOL history - is that Disk Loading determines hover performance and Lift per Drag ratio determines cruise performance, and they are mutually exclusive. A high DL determines a low L/D and vice versa.
Helicopters evolved to look the way they do because that's what worked. Anyone who ever reads aviation history and sees the pictures of all the stuff that was tried will know this. Physics has not changed since the earliest attempts at flight, nor has the air.

Furthermore, a multirotor drone thing isn't going to autorotate, so now you're stuck with relying on complex electrical and electronic systems to keep you from crashing. And with my experience with electrical things in airplanes, I know that it will not be simple, or cheap, or light, to achieve that.

I've said it before: Something really successful is likely to show up suddenly, all complete, and flying capably and safely. It will be kept quiet until then in order to get as many worldwide patents as possible, and to avoid the usual negative press from crowds of disappointed prospective buyers. It won't be something designed to fleece gullible investors.
 

henryk

Well-Known Member
Joined
Mar 8, 2010
Messages
6,723
Location
krakow,poland
This is the reason I believe the next "flying car" (I prefer personal aircraft) will actually have wings and able to transition to a more efficient wing-borne flying mode.
-yes !

f.e. "circular" wing =low span, L/D circa 10 ...
 

Aesquire

Well-Known Member
Joined
Jul 28, 2014
Messages
3,075
Location
Rochester, NY, USA
The L\D issue ( as a measure of performance/success ) is why I'm impressed with Black Fly. cruising on wings makes a big difference.

The Aston Martin craft is leather seats and pretty, but carries motors not used in cruise. Dornier and Yak built "successful" VTOL planes with " useless in cruise" lift engines, and the F-35 VTOL version has a big heavy fan & drivetrain that's dead weight between landings.

I really liked the Dornier. I suspect a "next generation" version with 4 Pegasus engine pods & without the eight lift engines would have been better.

Volocopter has at least given actual thought to the issues of multiple death blades that most of the "man carrying drone like multicopters" ( aka human cuisanarts ) ignore.

We need a good, unambiguous NAME for the human cuisanart types. ( which I deliberately miss spell for legal reasons ;). )

They Ain't Flying Cars.
 

Aesquire

Well-Known Member
Joined
Jul 28, 2014
Messages
3,075
Location
Rochester, NY, USA
 

Rhino

Well-Known Member
Lifetime Supporter
Joined
Apr 8, 2004
Messages
1,874
Location
KTHA
...USA Federal Government right wing terminology.
Oxymoron. You've got your left and right confused.
I think it's actually rather easy to build a flying car...
That's actually true. But the thread title says one that will succeed. That requires a viable, marketable product, and we're nowhere near having that. We never will be until we solve the dichotomy of what makes an airplane suitable vs what makes a car suitable. What makes a good plane doesn't make a good car, and vice versa.
...Physics has not changed since the earliest attempts at flight, nor has the air....
Been to Los Angeles lately?
 
Last edited:

jedi

Well-Known Member
Joined
Aug 8, 2009
Messages
3,008
Location
Sahuarita Arizona, Renton Washington, USA
Oxymoron. You've got your left and right confused.

That's actually true. But the thread title says one that will succeed. That requires a viable, marketable product, and we're nowhere near having that. We never will be until we solve the dichotomy of what makes an airplane suitable vs what makes a car suitable. What makes a good plane doesn't make a good car, and vice versa.

Been to Los Angeles lately?
Referng to post #79 page 4 "left and right confused"? No I do not think so. We must be speaking different languages. I thought the "Federation" was the left and Luke was inclined to the right. Also,** "The Force comes in two flavors: Light Side (good) and Dark Side (bad)."

We are on the verge of politics here so I can't say much more.

To bring the subject back to flying cars, Can we agree that Luke's "land speeder" had successful flying car attributes in spite of it's limited altitude and speed capabilities. It's superior off road capabilities and lack of dependence on airports or sky ports* as the electric VTOL multicopter junkies tend to say is what made it practical.

I think there is a lesson here.

* Volocopter (Homepage) is looking to hire VoloPort designers.
** Google "What are the two sides of Star Wars? ".
 
Last edited:

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
6,587
No pitch or collective control of the autorotating section means no control as to where it lands or at what vertical velocity, and it also means little stability. Just about as deadly as without the autorotative feature.

And it's just a picture, not a proven device. I could draw an antigravity machine, in flight, with people in it, flying at 600 MPH, but that doesn't make it real or possible.
 

REVAN

Well-Known Member
Joined
Dec 6, 2016
Messages
354
Location
Tucson, Arizona USA
Helicopters evolved to look the way they do because that's what worked.
I'll agree if you add, "for how it was being used". The thing is, helicopters never succeeded at fulfilling the role of a flying car, or PAV commuter, or whatever you want to call it. They are too expensive to build, too hard to to operate, too expensive to maintain and far to inefficient to compete with cars in more than 99.99% of potential applications. In fact, they lose pretty drastically to fixed wing airplanes in most applications as well. There is a niche for helicopter operations, as evident by the current helicopter market. However, it's a niche. It's not widespread and never will be without some disruptive technology to overcome the helicopter's inherent limitations.
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
6,587
There is a niche for helicopter operations, as evident by the current helicopter market. However, it's a niche. It's not widespread and never will be without some disruptive technology to overcome the helicopter's inherent limitations.
And that is the key. Some disruptive technology. Every helicopter operator would gladly buy a machine that could do more and cost less. But nobody has come up with such a machine. Nobody. It's not as easy as it seems to the wishful thinkers.
 

Rhino

Well-Known Member
Lifetime Supporter
Joined
Apr 8, 2004
Messages
1,874
Location
KTHA
Referng to post #79 page 4 "left and right confused"? No I do not think so. We must be speaking different languages. I thought the "Federation" was the left and Luke was inclined to the right. Also,** "The Force comes in two flavors: Light Side (good) and Dark Side (bad)."
You weren't talking about Star Wars. Nor was I.

We are on the verge of politics here so I can't say much more.
Yep.

To bring the subject back to flying cars, Can we agree that Luke's "land speeder" had successful flying car attributes in spite of it's limited altitude and speed capabilities. It's superior off road capabilities and lack of dependence on airports or sky ports* as the electric VTOL multicopter junkies tend to say is what made it practical.
The land speeder wasn't a flying car. It didn't travel on roads. And we're talking about Earth, not Tatooine. We have to come up with a concept that works here, and we aren't close to that.
 
Top