Flying Cars And Roadable Aircraft

[Stargazer]

they have to be two-bladed, which in turn drives the diameter of the wheels

Tell me if I'm wrong here... but did you just say that the number of blades determines the diameter of the wheels?

I could be wrong here, as I can claim no expertise in helicopter dynamics... but my impression is that whether a rotor has two, three, four, five or six blades doesn't change the length of the blades in a way that will dramatically increase the total rotor diameter. At the worst the increase in the number of blades would make for shorter blades, not longer.

Or am I sorely mistaken here?

 

[Arjen]

Two-bladed propellors allow them to be stowed without any bits sticking out.

 

[Stargazer]

Two-bladed propellors allow them to be stowed without any bits sticking out.

Point taken!

 

[robunos]

Arjen has it right, two-bladed propellers (rotors?) can be stowed fore and aft inside the wheel circle without 'bits sticking out'. However, I suppose propellers with more blades could be used, but they would have fold in order to stow fore and aft like a two-blader, when not in use.
A further thought. The small version is electric powered, but would this be possible with a version large enough to be manned? This question has already been touched on, here :-

http://www.secretprojects.co.uk/forum/index.php/topic,4537.0.html

cheers,
Robin.

 

[blackkite]

Hi Grey Havoc!
How do you think about the technical level of this super machine?

 

[Grey Havoc]

Looks promising. Scaling it up to a full size manned vehicle may prove tricky though.

 

[Arjen]

How about counter-rotating propellers to double the number of blades? I magine it would add some mechanical complexity, but not as much as folding the propellers.

 

[blackkite]

Looks promising. Scaling it up to a full size manned vehicle may prove tricky though.

Thanks. And propellers are little dangerous when vertical take off mode.

 

[Stargazer]

How about counter-rotating propellers to double the number of blades? I magine it would add some mechanical complexity, but not as much as folding the propellers.

Interesting thought... but that would necessarily add quite a bit to the weight, wouldn't it?

 

[Bill Walker]

Pardon the thread drift, but...

I wonder if electrical motors could revive the interest in counter-rotating coaxial props? Instead of a heavy and expensive coaxial gearbox, how about two electrical motors, the shaft of one running through the hollow shaft of the other? Maybe somebody who knows about electrical motors could tell us if two 50 horsepower electrical motors would be much heavier than one 100 hp motor.

 

[robunos]

Contra-rotating propellers are a good idea, although I still have my doubts about electric propulsion. Then again, two sets of motors might be lighter than contraprop gearboxes.
Another thought. At each propeller station, two superposed two-blade propellers, folding like scissors, opened at 90o for flight, and closed to 0owhen on the ground. 'Folding' this way would probably only require a small system similar to a feathering mechanism...
Even simpler, would 'biplane' props be efficient enough?


cheers,
Robin.

P.S. Should these ideas be found practical and adopted, I want my percentage. I'm serious.

 

[Stargazer]

Even simpler, would 'biplane' props be efficient enough?

"Biplane props"?? As in "two rotors superimposed and rotating together at the same speed"? Would that be of any help, and has it ever been done before?

 

[Bill Walker]

Even simpler, would 'biplane' props be efficient enough?

"Biplane props"?? As in "two rotors superimposed and rotating together at the same speed"? Would that be of any help, and has it ever been done before?

Tried by Breguet brothers in 1907, and not seen since. I suspect there is a reason...

 

[robunos]

Even simpler, would 'biplane' props be efficient enough?

"Biplane props"?? As in "two rotors superimposed and rotating together at the same speed"? Would that be of any help, and has it ever been done before?

Tried by Breguet brothers in 1907, and not seen since. I suspect there is a reason...

Just an idea I had............

I think the problem with biplane props is you can't get enough separation between the individual propellers for them to be efficient enough without insurmountable mechanical problems.
OTOH, I think my 'scissor-fold' props would work...

Weren't the Breguet 'rotors' actual biplane wing assemblies, complete with wire bracing? Draggy...

cheers,
Robin.

 

[Arjen]

I think scissor-folding props would be less complicated than counter-rotating props. Probably lighter as well. Best of luck with getting those royalties

 

[jetboy]

Hi,so really ive wasted my time with this,its not real then?



cheers Don

 

[Jemiba]

Folding the prop blade uwards should be possible, too, as the diameter is limited to the inner radius of the wheel
either. So, a prop as used sometimes in powered gliders could be used, I think.

@ Jetboy : Fitting rims to those two props, protruding over the sides and then using this vehicle on the ground as
a kind of motor bike !

 

[Grey Havoc]

It's the difference between things that fly, and things that don't fly but have to ride out a pothole at 70 mph and protect their occupants against a drunk in a Ford F350. A Cirrus SR22 has about the same cab volume as a 5-series BMW or similar, but has an empty weight of about 2200 pounds versus 3500-plus pounds for the car.
And given that nobody has come up with a really successful amphibious car yet (pace all you Amphicar fans out there) asking for a flying car may be ambitious.

If by successful you mean commercially successful, I have to concede, but there are at least two amphibious cars displayed on YouTube that are wildly successful from a technical standpoint - one of them with caterpillar tracks, of all things. Lightweight structures and powerplants with higher power density really are making a difference there.

Going OT for a moment; With regards as to the Cirrus SR22: http://www.telegraph.co.uk/news/aviation/10104568/Struggling-plane-floated-to-the-ground-using-its-own-parachute.html

 

[Jemiba]

The rescue system just did, what it is designed to do ! IF flying cars would become common, such devices would be absolutely necessary,
I think. Nevertheless, looking at this incident, for me it's a point against the flying car, because such accidents jeopardise people at places,
they are safe still yet. Hardly imaginable to be endangered by a traffic accident on a school yard, church yard, backyard of a kindergarten,
or open-air theater today, at least statistically not relevant. With the propagation of flying cars and its use as advertised this could change !
It won't be regarded as standard air traffic by the public, I think, and the, back to this incident, the first worker, who will NOT succeed to
jump from the scaffolding to get out of harms way, may well kill this idea !

 

[bigvlada]

Pardon the thread drift, but...

I wonder if electrical motors could revive the interest in counter-rotating coaxial props? Instead of a heavy and expensive coaxial gearbox, how about two electrical motors, the shaft of one running through the hollow shaft of the other? Maybe somebody who knows about electrical motors could tell us if two 50 horsepower electrical motors would be much heavier than one 100 hp motor.

It could be done. Electric Cessna 172 made several flights and they said the goal was to have electric engine that can replace the internal combustion one in the 150-200hp range.
http://evworld.com/news.cfm?newsid=28964

 

[kcran567]

A car that flies. To me its an oxymoron because I really don't want to drive in a car that looks like a Cessna, and I don't want to fly around in an airplane that looks like a compact car. They do neither too well. Maybe when technology allows the car to float off the ground like a Star Wars landspeeder using anti gravity. But thats 200 years away. I like the idea of a compact winged lifting body aircraft to be a personal one seat aircraft to get around in on a daily basis though, but not to drive on the ground to pick up groceries with.

 

[Grey Havoc]

http://io9.com/a-treasury-of-flying-cars-from-the-golden-age-of-aviat-510910460

 

[hesham]

Hi,


here is the Pescara flying car of 1921.


http://jalopnik.com/5916189/the-ten-craziest-failed-flying-cars/

 

[hesham]

Also from the same source,


the David Dobbins Simcopter.

 

[Stargazer]

In a topic about a Thiéblot patent for Fairchild concerning a twin-boom transport design, Jos Heyman asks the following question:

The full patent shows a reference to NX59711.
Aerofiles.com report on this as follows:
Aerocar 1946 = 2pChwM; 130hp Franklin 6AC; span: 30'0" v (est): 128 range (est): 310. Ted Hall. Roadable with demountable wing and twin-boom, twin-tail unit, a development by Hall of his twin-boom auto-plane concepts. It is uncertain if this was ever specifically produced under the Southern banner, or if it was one of Hall's projects in the works, as it was first flown at San Diego CA in 1939. POP: 1 [NX59711], made several test flights, but proved to be underpowered and the project was abandoned in the post-war slump.
Beg's the question wether the Fairchild design was supposed to have demountable tail unit (seemingly the only link to NX59711).

I'm still not sure why this Southern Aircraft prototype [NX59711] is mentioned in this Fairchild-related patent. What I can say however is that the Aerofiles entry is wrong concerning that aircraft. Here is the text at the back of a publicity photo of the type in flight:

"THE ROADABLE, EXPERIMENTAL AIRPLANE-AUTOMOBILE IN FLIGHT -- Southern Aircraft's experimental airplane with an automobile chassis for fuselage, flew successfully at Majors Field, Greenville, Texas. The wings, propeller and tail sections on the strange craft can be removed, making the Roadable a conventional automobile ready for highway operation."

So, clearly:

• About the question that "It is uncertain if this was ever specifically produced under the Southern banner", we do have a definitive answer here that it was.
• As for the name of the aircraft, it was called the Roadable, not the Aerocar.
• As for the location of the first flight, although it doesn't really say here that the "successful" flight depicted was the first one, Southern Aircraft was a Texan company and there is no reason why Southern would have first flown it in California, then shipped it back in Texas... And so if the aircraft ever ended up in San Diego, it must have been after the demise of Southern Aircraft and departure of Ted Hall.

 

[Antonio]

Latest developments

http://www.aeromobil.com

http://www.bbc.co.uk/news/technology-24635758

 

[Jemiba]

Nicely designed, a very good looking roadable aircraft, but as a two-seater it's as
long as a Lincoln Town Car (stretched version !). So I think, it's just another toy for
grown-up boys, but still missing suitability for daily use.

 

[mithril]

here is a flying automobile.. really more of an offroad buggy than a car though.
http://www.gizmag.com/skyrunner-flying-parasail-car/29627/

 

[Jemiba]

here is a flying automobile.. really more of an offroad buggy than a car though.

That's the minimal solution, I think. Probably not needing a PPL and able to use quite a lot
of places for take-off and landing, here it's the car part, that to myopinion somehow lacks
suitability for daily use.
About the Aeromobil, watching it taking-off, I have the feeling, that it needs even smoother
runways, than most aircraft !

 

[Grey Havoc]

http://blog.sfgate.com/techchron/2013/11/20/google-flying-cars-zee-aero/#18174101=0​

 

[Jemiba]

An elecrically driven manned multicopter ! To be used as a car, to y opinion the wheels would
have to be enlarged considerably, as with those small castors, it would have the same driving
characteristics, as a shopping cart on the mentioned grocery store !

 

[Orionblamblam]

To be used as a car,

The term "flying car" is one of those that seems misapplied. To me, a "flying car" is a (primarily) road vehicle that can (secondarily) fly. A "roadable aircraft" is an aircraft that be taken on roads. Vehicles like this, and the Moller concepts, are not "flying cars," since they are not even remotely roadable. "Personal VTOL" would be better, but it doesn't exactly roll off the tongue.

 

[Jemiba]

Good definition, to my opinion, but looking at most publications about them, the terms are more
or less used interchangeably. and the vehicles built until now are more or less all roadable aircraft
only, with the exception of those motorised paragliders maybe.
A "personal VTOL" principally could change matters, because the need to drive more than, say 100 m
would be eliminated, if landing on every open spot would be allowed. So it's back to the problems of
certifying such a thing !

 

[F-14D]

Good definition, to my opinion, but looking at most publications about them, the terms are more
or less used interchangeably. and the vehicles built until now are more or less all roadable aircraft
only, with the exception of those motorised paragliders maybe.
A "personal VTOL" principally could change matters, because the need to drive more than, say 100 m
would be eliminated, if landing on every open spot would be allowed. So it's back to the problems of
certifying such a thing !

I would say the problems with certifying a personal VTOL and the operators would be enormous, especially given the landing issue you mention. Airplanes now are expensive enough that they tend to "cull" the general public from getting one. And that's a Good Thing. The new East span of the SF-Oakland Bay Bridge opened Labor Day weekend. Less than 12 hours later (I think it was actually less than 8) they had their first accident caused by a drunk driver. Also, the same night, someone tried to drive to Oakland on the old, closed span. The story was the person didn't realize it was closed. To do so, they had to miss all the news reports for months, signs, flashing lights, cones, etc. and maneuver around all the barricades. Do we really want these people to be able to not only run into, but also plummet down on us?

A roadable aircraft, OTOH, might be a worthwhile thing if it ever could be made effective (i.e. not a lousy airplane coupled with a lousy car) economically and be certified at a less than ruinous cost (are you listening FAA & DoT?). Interesting monograph on this at: http://www.volanteaircraft.com/role.htm

 

[F-14D]

Besides, Mike Mercury had one of these over 50 years ago!
(kinda looks like something Moller would come up with).

 

[Jemiba]

Yes, that's probably, what common man would have described as a "flying car", when the
substitution of cars at least by helicopters seemed to be around the corner. Strange, that
today very few people are still having this idea anymore! Our expectations for the future
have become have become smaller, as I don't dare to say: more realistic. :-\

 

[dan_inbox]

Our expectations for the future have become have become smaller, as I don't dare to say: more realistic. :-\

In the general population, the proportion of drivers capable of passing a Private
Pilot Licence has not increased by much.
Conversely, the proportion of idiots/fanatics/jihadis/cuckholded/begrudged/etc
who would be a serious danger to the public if they could crash an airplane onto
whatever, this proportion is higher than ever.... and not going to diminish
anytime soon.

(how do I get rid of that darn flag?)

 

[Jemiba]

That's a problem, although a car can be used in a very similar fashion, too. Of course,
still yet, you're relatively save in your backyard, but with easy access to rc-models/multi
copters, that can be guided via real time video transmission, that safety has gone anyway.

 

[Orionblamblam]

In the general population, the proportion of drivers capable of passing a Private
Pilot Licence has not increased by much.
Conversely, the proportion of idiots/fanatics/jihadis/cuckholded/begrudged/etc
who would be a serious danger to the public if they could crash an airplane onto
whatever, this proportion is higher than ever.... and not going to diminish
anytime soon.

This is the "precautionary principle" line of argument. When someone comes up with a good idea and it is shot down, not implemented, or indefinitely delayed because of...
"Yes, but... crazy people!" Thus no flying cars (or low-cost practical aircraft).
"Yes, but... accidents!" Thus no new nuclear powerplants (yay, we get to burn more fossil fuels)
"Yes, but... booga boooga!" Thus people freak out over vaccines or particle accelerators

It's basically the enshrinement of cowardice into law or policy in order to justify the maintenance of the status quo. Very useful for those already in power as a way to prevent innovation... and to protect their positions.

 

[Jemiba]

If flying cars become a standard means of transport, maybe a guidance system could be
installed as a mandatory measure, It would allow use only over approved areas, or better
fly the vehicle autonomously in such approved airways. Still faster, than going by car, but
avoising at least most densely populated areas. The political quarrels will be interesting, of
course, about what will become a restricted area and what not !