On Apr 14, 10:11*pm, wrote:
* * *Sure, the air will swirl around some as it leaves the prop. It
has to, since there is no such thing as a drag-free propeller. But
it's manageable. Anyone who thinks he can design a better propeller or
airplane or anything else is well advised to do his research first so
as to avoid spending vast sums of money making the same mistakes
dozens of other guys have already made. If the OP, who is a PPL
student and has been known to "know better than the experts" in the
past, wishes to design and build himself a phenomenally new and
successful airplane or flying car, he'll have a pretty hard time doing
it. There are hundreds, maybe thousands worldwide, of aeronautical
engineers who know the limits of the physics and materials involved
and they are often employed at very good salaries by huge aircraft
manufacturers who wish to save even a few percent on fuel consumption,
drag, safety risks and other costs just to give themselves a
perceptible advantage over the competition. Any large improvement at
this point is going to require some new technologies that don't exist
yet. Better to spend the time discovering those new technologies.
There are many garages and barns and landfills full of pointless
efforts at designing a new airplane. Most successful new designs are
variations on the same old theme we've had for a long time now.

It is true that I am still a student PPL. And it is true that I tend
to fish in ponds long deemed to be devoid of fish. But I know that I
know less than others. However, in areas of science that I am
passionate about, I feel that it is better to not accept stocks answer
that smell fishy.

On the matter of flying cars, yes, someday I would like to take a shot
at design some kind of flying vehicle. It would be a daunting task to
say the least, but that would not deter me. Though it is true that
1000's of people have sought to make flying cars and failed, if you
look at their designs, many of them are cars with wings on them. I
doubt that this is the right way to make a PAV.

In the early days of flying, there were many things tried by many
people that we now know with certainty could not possibly work lest
they violate basic physical principles. Hindsight might be 20/20, but
forethought and more rigorous paper analysis could have preempted many
of these attempts, but people tried them anyway. They tried them
perhaps because they could not contain their passion and desire to
make a breakthrough. This is where I get my encouragement from, not
from thinking I know better. I learned a while back that discplined
thought, the kind that requires doing nothing but sitting still and
thinking, can be an inexpensive way to solve a problem.

I do have an idea about propulsion, which, ironically, was derived
from my initial exploration into whether backwash could cause lift.

*IF* my suspicions are correct, there would exist a new type of
propulsion system that would have very desirable attributes as far as
flying cars are concerned. It would, indeed, require a restatement of
the explanation of aerodynamics above the wing. But as I have no idea
whether it is correct, so I cannot yet say either way. I have tried
little paper models at home, which all seem to confirm my suspicions,
but needless to say, paper models do not constitute proof, and in any
case, I do not understand the physics well enough to be able to
explain them to someone else, even though I am convinced that what is
happening is _not_ entirely explained by prevailing aerodynamic
theory.

So if I were to begin fiddling with this problem, the first thing I
would do is focus on the parts that matter, to see if there is
anything worth pursuing. If it turns out that I am wrong, I would
abort.

I would _not_ spend years tweaking some aspect of the vehicle until I
finally squeezed 3% more efficiency out of it. As you noted, there
are many people who are much better than I ever will be at that.

-Le Chaud Lapin-