Just to place Adaptive Stagger Rotor idea in the public domain.

[Dave_Jackson]

Sikorsky has thirteen patents for Variable Diameter Rotors.

OK, UniCopter now has one 'patent-excluder' for Adaptive Stagger Rotors (http://www.unicopter.com/1464.html).


Dave

[IFMU]

Sikorsky has thirteen patents for Variable Diameter Rotors.
Dave
... but not many flying!

-- IFMU

[Graviman]

:eek: Complicated powertrain with multiple gearboxes not complex enough eh, Dave?. Hmm, sliding spline or electric motors - you've probably saved some mad inventor the patenting costs... :uhoh:

Mart

[Dave_Jackson]

Mart,

Which of Sikorsky's 13 patents are you refering to? ;)


6,655,915 ~ Drive system for the retraction/extension of variable diameter rotor systems
6,578,793 ~ Method and apparatus for fiber strap termination
6,568,906 ~ Conformal sliding bearing
6,454,532 ~ Harmonic drive system for the retraction/extension of variable diameter rotor systems
6,398,497 ~ Blade lock system for variable diameter rotor systems
6,030,177 ~ Drive system for a variable diameter tilt rotor
6,019,578 ~ Variable diameter rotor blade actuation system
5,735,670 ~ Rotor system having alternating length rotor blades and positioning means therefor for reducing blade-vortex interaction (BVI) noise
5,655,879 ~ Mounting arrangement for variable diameter rotor blade assemblies
5,642,982 ~ Retraction/extension mechanism for variable diameter rotors
5,636,969 ~ Torque tube/spar assembly for variable diameter helicopter rotors
5,620,304 ~ Rotor system having alternating length rotor blades and positioning means therefor for reducing blade-vortex interaction (BVI) noise
5,620,303 ~ Rotor system having alternating length rotor blades for reducing blade-vortex interaction (BVI) noise


Dave

[IFMU]

Mart,

Which of Sikorsky's 13 patents are you refering to? ;)


Dave

Dave,

I bet they pay guys to make that stuff up.

-- IFMU

[Graviman]

How many guys/gals work on the Long Island site, anyhow?

Mart

[21st Century]

Sikorsky submitted a Variable Diameter Rotors (VDR) Tiltrotor concept to NASA Ames quite a few years ago including a scale model. The NASA engineers tasked with the initial assessment felt that it did in fact incorporate enough safe guards to be a potentially viable production aircraft. (that was late 90's and not much or any forward movement has been released from either NASA or Sikorsky since).

[Dave_Jackson]

From today's news:
"The United States has built a regime on the misguided notion that stronger patent rights always lead to more innovation,"
"The agency granted 164,000 patents in 2004, up from 90,000 in 1990:"
Full story (http://www.theglobeandmail.com/servlet/story/RTGAM.20061128.wpatentt29/BNStory/Technology/home)

It would be interesting to know what percentage of these patents are ever utilized in commercial products.


Perhaps, Sikorsky has no intention of producing variable diameter tilt-rotors. Unlikely, but, maybe the intent of the patents is to restrict Bell's ability to improve their competing tilt rotors.


Dave

[Matari]

I searched this forum and I couldn't find this variable diameter rotor concept referenced anywhere. Mods, please move or delete if redundant.

Interesting video from 2007:

Helicopter Blade Technology - Variable Length Rotor - Video - Breakthrough Awards - Popular Mechanics (http://www.popularmechanics.com/technology/industry/4224761.html)

This concept relies on centrifugal forces to move the blade out at higher RPMs, and a spring mechanism to bring it back in at lower RPMs. Wonder what advantage that is given that most rotor systems operate at a more or less constant RPM (within green arc, of course).

[Dave_Jackson]

Matari,

There may not be any reference on this forum but their is quite a bit of info on Google.

This is a 126 page report The Attributes of a Variable-Diameter Rotor System Applied to Civil Tiltrotor Aircraft (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19970005490_1997006487.pdf)


Dave

[riff_raff]

Dave,

As I'm sure you're well aware, most patents are only worth the paper they're written on. I'm not the brightest mechanical engineer around, but give me a few days and I can come up with a way around 99% of the mechanical utility patents I've seen. It's not that the patents were poorly constructed, it's just the nature of the design process.

Even though they're mostly worthless in the long run, there's two reasons that large companies still file lots of patents. First, they have lots of attorneys on retainer with nothing better to do. And second, they have a fiduciary obligation to their shareholders to at least make a token effort to protect their IP.

As for Sikorsky's VDR, they abandoned the idea a few years back when it became obvious that the complex device could never likely be made reliable enough for actual service. However, they have been asked to take a second look at the concept as part of the US military's JFTL study program.

Ares Homepage (http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogScript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3A27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3A36f8aeda-b332-433e-9d4a-25f9404ee5f2)

[Dave_Jackson]

riff_raff,

I agree with what you are saying.

The US patent system needs some overhauling. The Congress has been try now for a number of years but it is said that the drug industry and two specific companies have been fighting it. United Technologies was one and I think that 3M was the other.

Dave

[John R81]

Off topic (ish) but in case you want to check on patents then each country has its own agency and most can be accessed online. The UK one is at Intellectual Property Office - Welcome to the Intellectual Property Office (http://www.ipo.gov.uk/)

The "patents tab, online patent services and search patent " will bring you to the option of seraching in 4 different ways, the most useful being the EPO database from which you can perform a world wide patent search from the comfort of your own keyboard.

Selecting the quick search, world wide, by person, and entering "sikorsky" gets 838 hits, and you can refine from there using the advance search option.

Interestingly, Eurocopter have 1,798 patents (more than Sikorsky), 373 of them concerning rotors in some way, nothing on variable diameter rotors but 1 (1997 filing) for variable pitch rotor blades made using a resin moulding.

Amazing what you can do with the internet when bored.

Edited to add:

Frank D Robinson has 2 patents and neither relate to tree surgery

[forget]

riff raff, As I'm sure you're well aware, most patents are only worth the paper they're written on.

50 to 1 he doesn't hold a single patent. Any takers? :hmm: