

The Fastest Helicopter on Earth - gvb
http://spectrum.ieee.org/aerospace/aviation/the-fastest-helicopter-on-earth/0

======
joshwa
While interesting, this is a puff piece written by the designers of the
helicopter at Sikorsky.

------
todayiamme
Is it just me or the writing style of this article is really weird? It's as if
different people have written different sections. Some of it sounds like a
pre-flight briefing manual sans the helpful illustrations and other parts
sound like a PR fluff piece. For example;

>>>But here's the catch. When a helicopter flies forward, the rotor blades
experience a dramatic variation in airspeed. That's easy to see if you imagine
a miniature version of yourself perched on the tip of a helicopter rotor
blade. If the helicopter were hovering, you'd feel a constant 800-km/h wind in
your face as the rotor spun around. If the helicopter were to fly forward, you
would note that the wind was stronger on what's called the advancing side,
when the rotor was moving in the same direction as the helicopter, but that it
would be noticeably weaker when the rotor was on the retreating side. By the
time the helicopter reached 150 km/h, you would feel a wind speed of 950 km/h
on the advancing side, versus 650 km/h on the retreating side....<<<

I had to re-read this paragraph at least 2-3 times to understand what it
exactly meant. It was just too vague. What direction should I face? Am I
moving clockwise or counterclockwise? What does it mean that the rotor is
moving in the same direction as the helicopter?

Then there was this paragraph, which sounds... fake considering the tone of
the rest of the article.

>>>With everyone's nerves on edge, the X2 started up its engine at 6:30 a.m.,
and the helicopter took off. Within a few minutes the X2 had reached a speed
of 350 km/h. A dozen people watched from the ground as the airspeed crept up,
first to 400, then 410, and finally topping out at 435 km/h—not quite the goal
we'd set, but good enough for this round. Cheers and applause broke out on the
ground. The pilot slowed the X2, turned it around, and flew back to land on
the runway.<<<

The same person who had trouble explaining the simple imagery of a rotating
blade can't write something as flowery as that. It's just too unlikely.

~~~
bad_user
I understood that paragraph without problems, and I'm not even a native
English speaker.

------
avar
While the Sikorsky X2 might have some niche uses rescue missions probably
aren't one of them. It's tiny. A tiltrotor[1] aircraft like the V-22 Osprey
seems a much better fit if you need to get there fast _and_ do something
meaningful like rescue work.

1\. <https://secure.wikimedia.org/wikipedia/en/wiki/Tiltrotor>

~~~
whyenot
The X2 is not a production model, it is an experimental aircraft. According to
the article, the technology used in the X2 will eventually be used in
production models that will presumably "go fast and do something meaningful."
Otherwise nobody would buy them ;)

~~~
avar
Well there's still plenty of uses for a fast and helicopter. Patrol missions
for one. But hopefully they'll be able to scale this up to bigger sizes.

Does anyone know if that would be much harder? I.e. is it inherently harder to
make heavier helicopters go faster? Or do you just have to scale up the
fabrication.

~~~
icegreentea
I imagine like everything in aerospace, 'just scaling up' isn't as simple as
it is. Drag increases non-linearly as you scale up for one thing, and with
something as tricky as the rotors of helicopter, you probably have to do all
sorts of nuts stuff to get it to work. For one thing, you can't just make the
rotor span larger (with same rotation speed), cause then your increasing the
velocity of the rotor tips which could cause all sorts of problems.

------
Mongoose
Anyone know of a decent biography of Igor Sikorsky? Most of the ones I'm
finding on Amazon are either fluff or kids books.

------
akamaka
The article really should have mentioned the BA-609 tiltrotor aircraft. It's
the civilian version of the V-22, and nearly ready for production.

The BA-609, with the speed and range of an airplane, has tremendous potential,
and is _the_ reason why Sikorsky started resealching faster helicopters.

~~~
philwelch
The V-22 should make for a very interesting engineering story when all of the
history comes out. Tiltrotors inherently have a lot of moving parts, plus a
very complicated aerodynamic profile as they transition from helicopter mode
to airplane mode. It took decades to develop it, at least one fatal accident,
and a lot of technology risk throughout, and all the while it was a prime
candidate for cancellation. The only thing that saved it was its suitability
for the Marine Corps, who needed an aircraft that could carry more Marines a
longer distance than helicopters.
([http://en.wikipedia.org/wiki/File:MV-22B_combat_radius_in_Ir...](http://en.wikipedia.org/wiki/File:MV-22B_combat_radius_in_Iraq_compared_with_CH-46E_combat_radius.svg))

It's probably not too far from the truth to say that, just like stealth
aircraft, we wouldn't have usable production tiltrotor aircraft today if it
wasn't for the political tendency to spend vast amounts of money on
unnecessary and implausible military contracts. Not an argument either way,
just an observation.

~~~
icegreentea
To be fair, initial stealth technology wasn't even THAT expensive. The initial
development of 'true' stealth (Pave Blue/F-117) cost about 2 Billion USD in
R&D and a total of about 7 Billion for all the planes and everything else.

Furthermore, it wasn't even that implausible. Some Soviet physicist already
wrote the paper telling us how to calculate Radar Cross Sections. The initial
prototyping was a huge success (pretty much matched up exactly what their
expected/calculated values).

Now, the B2. That's a different story. It's very hard to justify 2 Billion
dollar bombers, no matter how you spin it.

Linkie here: <http://www.ausairpower.net/Profile-F-117A.html> and also Ben
Rich's excellent (though somewhat biased) book Skunk Works.

~~~
philwelch
The 2 billion dollar price tag is misleading, though--the design cost was
supposed to be amortized over a much larger order of planes.

------
regehr
Everyone knows Airwolf is faster.

~~~
adolph
Truely: Airwolf's conventional top speed is 560 km/h compared to the X2's 435
km/h. With turbo boosters, Airwolf could go Mach 1+, so really nothing has
progressed past the 1980's.

Source: <http://en.wikipedia.org/wiki/Airwolf_(helicopter)>

~~~
jacquesm
Except that airwolf's special capabilities are all fictional.

------
unwind
It must have a massively robust landing gear design.

~~~
thu
Do you mean more massive than a normal helicopter? Why? The article seems to
state that the newly available technologies made their new helicopter lighter
than before.

~~~
unwind
Heh. I see I was down-modded, which wasn't very surprising. I was trying for
exactly the kind of pun/humor that I know HN doesn't appreciate.

ObJokeExplanation: For me, the wording of the title was misleading in a funny
way, since helicopters generally don't break speed records while _literally_
on Earth.

~~~
randallsquared
HN does sometimes appreciate that, but you have to lead a bit. Maybe if you'd
quoted the title immediately before your response, since most people will have
read one or more other comments (and maybe the article itself... shocking, I
know) before reading your comment. The headline has expired out of memory at
this point. That's my excuse for why I didn't get it.

------
tocomment
Why is the double rotor design not more popular than the way most helicopters
are made?

~~~
gvb
My guess is complexity. The double rotors require coaxial drives and the
helicopter itself ends up being taller. The top rotor maintenance is going to
be more difficult.

The Kamov company's helicopters were all(?) double-rotor.
<http://en.wikipedia.org/wiki/Kamov>

Kamen Aerospace has double rotor helicopters without the coaxial drive
(interleaved rotors) <http://en.wikipedia.org/wiki/Kaman_Aircraft>

~~~
stan_rogers
Complexity, yes, but for a different reason -- gyroscopic precession. Cyclic
inputs for differential lift require that the actual (mechanical) blade
adjustment be at an angle to the change in the lift produced. With a single
rotor you can accomplish that with a simple mechanical linkage (and a bit of
body english -- the angle of input precession is rarely at the "proper" 90
degrees). Counter-rotating blades mean two sets of blade pitch controls (swash
plates, rods, followers and linkages, etc.) and, if you want to avoid
unplanned pitch adjustments, a servo system that can moderate cyclic control
input based on direction (input will be much more sensitive to fore-aft
adjustment than to left-right without a compensation circuit).

~~~
jacquesm
> if you want to avoid unplanned pitch adjustments

I read that as 'detours to the nearest hospital'.

