

Australian built Hoverbike prepares for takeoff - yock
http://www.gizmag.com/hoverbike/18813/

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saulrh
On the one hand, do want. On the other hand, if I remember correctly the only
people that survived the Endor speeder bike chase were Jedi. On the other
other hand, maybe this would finally fix the "drunk driving" problem, one way
or another.

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hugh3
Bad places to use a speeder bike:

1\. In a dense forest

Good places to use a speeder bike:

1\. Most other places

The Empire was not big on picking the right tool for the right job.

~~~
SamReidHughes
Using a speeder bike in a forest is fine if you drive at a safe and
comfortable speed. It's when chasing jedi that things go sour.

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hugh3
I was unconvinced, until I read this bit:

 _Possible applications include aerial cattle mustering_

Now I have a new dream job: hoverbike cowboy.

~~~
underwater
Large farms in Australia use trail bikes and helicopters to muster cattle
already.

~~~
whatusername
For refernce -- Anna Creek Station is slightly larger than Vermont or Isreal.
<http://en.wikipedia.org/wiki/Anna_Creek_station>

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Luyt
Looking at <http://www.gizmag.com/hoverbike/18813/picture/135534/> , I'd like
to see the protective grille extend over the entire front fan duct, with holes
small enough that not even your hands can get through. Suppose you have a
small collision with an object, which could throw you over the handlebars and
into the front propeller...

~~~
regularfry
I'd like to see one that's not a first-shot prototype :-)

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tvon
Curious why they decided to only put an apparently safety cage over part of
the propellers, that's fine if you don't fall off and never wreck, but I could
easily see a mishap exposing a limb to the unprotected region.

~~~
brettnak
In the article he states that he will be fully covering the rotors.

"The propellers, which are currently largely exposed, will also be fully
covered in a mesh to ensure limbs don't get too near the blades."

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extension
What about _hair_?

~~~
Tichy
Saves the cost for a haircut?

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inam
"...there will be room for a computer override of sorts to stop amateur pilots
tipping over"

I don't know. I still think there's too much of a risk in the whole thing
being top heavy due to the blades being below the rider. Envisioning being at
5,000 ft. and all of the sudden looking at the world upside down while
rocketing to the ground.

~~~
saulrh
Most high-performance combat aircraft these days are rather aerodynamically
unstable and only stay in the air because their computers are constantly
correcting, and they do it all with thirty-year-old technology. Plus, remember
those quadrotor drones. This thing will only crash if its computer does, and
the government is going to force them to make their software so bulletproof
that that's not going to happen.

~~~
Someone
…and by the time that software is so bulletproof, this technology will be 30
years old, too.

That is a bit of an exaggeration, but with modern designs, you need wind
tunnel data, you have to program a simulator, so that you can test control
software without crashing a zillion expensive hardware systems, you need
ejection seats and an array of test pilots trained in a flight simulator that
behaves exactly like the hardware is thought to behave, etc.

The advantage here is that you could program the software so that it always
stays far, far away from danger zones. With fighter aircraft, that is not an
option. However, if you do that, the thing will not sell.

~~~
saulrh
True, but this is also several orders of magnitude simpler than a modern
combat aircraft. It has vastly simpler dynamics, it doesn't have to deal with
control surfaces, it doesn't have to be stable with irregular patches of
supersonic flow on its wings, and so on. It'll probably only take three or six
years, I bet.

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nradov
It's a cool idea but I expect it will have a serious dead man zone between
about 40 - 200ft altitude. In that range you're too low to use a parachute but
too high to survive a crash.

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nikcub
This didn't work in the 50s:

<http://www.aviastar.org/helicopters_eng/bensen_b-10.php>

but it may work today with fly-by-wire

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Kilimanjaro
I like the concept but, can we replace a huge propeller with three or four
inline and directionable small propellers for better stability?

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tocomment
You get less thrust that way.

~~~
redthrowaway
Also worse efficiency, more complexity, more expense, and more things to go
wrong.

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saulrh
And, since this is already being steered by a computer-controlled vectored
thrust system, giving it more fans won't make it any more stable in the first
place. This system is plenty actuated.

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marssaxman
Want this so badly.

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rkon
Google 'Ground effect'. Floating on an air cushion 2 feet off the ground just
proves that he can strap two overpowered fans together -- it's not actually
generating much lift like a helicopter would. He'll definitely make it to
10,000 feet... when he has two fans that are each two miles wide.

~~~
saulrh
I don't think that ducted fans get a lot of wing in ground effect, given that
ducts already prevent the formation of wingtip vortices.

~~~
rkon
I don't think ground effect while hovering involves wingtip vortices at all.
His 'flying' figures are only speculation, and all he's proven is that he can
hover.

His 'official' specifications: " _Hover (out of ground effect) – >10,000ft
(estimated)_"

"Assuming mass moved is constant then a helicopter hovering in free air will
be required to produce a force equivalent to V2 (speed after passing through
the rotor) - V1 (starting speed of air) where V1 is some value above 0 given
that the air is already moving downwards before reaching the rotor.

When close to the surface (generally considered 1/3-2/3 of the rotor
diameter), air forced downwards through the rotor disc is restricted in its
flow by the ground. This produces an area of high pressure below the disc and
in turn, reduces the duct effect and hence the downwards velocity of the air
above the disc. This reduces V1 while V2 remains relatively static, so the
value of V2 - V1 increases. From the equation F = M x A we can see that the
'lift' of the rotor disc is greater when in ground effect."

[http://en.wikipedia.org/wiki/Ground_effect_(aircraft)#Wing_i...](http://en.wikipedia.org/wiki/Ground_effect_\(aircraft\)#Wing_in_ground_effect_with_helicopters)

~~~
saulrh
Also from the ground effect page:

    
    
      Wingtip vortices are a major cause of induced drag,
      which refers to any drag created as a side effect of
      generating lift.
    

Less drag -> more efficiency -> less power required to maintain altitude. I
don't know how much of a factor this would be compared to the cushion, though,
so we'll just have to wait and see. Given that he's already bought and engine
and molded a nice, shiny shell, my guess is that he has plenty of power.

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maeon3
Roll up to the club with this and accidentally put out the windows of the cars
next to you when a rock gets lifted up and hurled at 250 mph.

