Nope, pic I saw was greener.
-- IFMU

Mart,

Walter Rieseler is referred to, in Germany at least, as the 'forgotten pioneer'.

I think that you will find his unique control system very interesting. Here is information on it;

• Wilford WRK Gyroplane
• On the NACA Search page and Enter Search Term 'TN-492'.
• US patent 1,975,124

____________

IFMU,

The grass is always greener on the other side. ;)


Dave

In searching for the picture, I found this:

http://www.aviationtoday.com/Assets/...-Left-Quad.jpg

But this looks like an old picture compared to the december issue of AIN.

Unable to download NASA pdf of control system analysis, but yes it was ahead of it's time. It certainly demonstrates that a cost effective hingeless gyro is practical. Maybe even manouvreable.

I think part of the difficulty with modern hingeless rotors is that the rotor frequency is so much higher now, due to the higher speeds and lower rotor mass. This means that any rotor eigenmode is comparable to the rotor frequency, so there is inevitably lead angle required in the pitch link. Although the tip radius was quite small, those tip heavy blades would likely have all sorts of interesting modes.

Actually, there are days when i catch myself wondering whether you are right about laterally seperated rotors. It would push roll reaction times way down, since heli does not have to pendulate to new equilibrium. I have even pondered about smaller control only rotors, like Sikorsky's early VS-300! But these days a good SCAS control system can response shape the cyclic input to get a reasonable response. I think keeping the cost and weight of the machine down is more important.

It will be interesting to see how the X2 development engineers overcome the difficulties if the envelope is pushed above 250KIAS. Clearly active tip control will become critical to avoid blade divergence. I would be curious how much higher the blade 1st bending frequency is pushed too. So roll response may approach that of fixed wing...

Mart,

In IFMU's article it says; You mention;Why does Sikorsky feel that 6,500 pounds is the lower end for ABC helicopters? There does not appear to be any technical reason for this remark. Perhaps, Sikorsky has no interest in them, or in other companies, building ABC helicopters with less than 6 seats.

_____________


Rieseler's means of producing 'Absolutely' Rigid Rotors by using aerodynamically balanced pitch instead of aerodynamically balanced flap is ingenious.

I'm going to look into it further, since it might be a logical step toward the UniCopter's and the Nemesis' Advancing Blade Concept. It will be posted as a separate topic on a new thread from this X2 thread if it continues to look good.


Dave

Here's another similar picture I found on some German site:
http://img505.imageshack.us/img505/861/x2wj0.jpg
and this one was from last year:
http://www.vtol.org/news/X2GroundTestStartnightime.jpg
-- IFMU

Rieseler, helico or tail-sitter???

What difference with a tail-sitter?
http://www.rotaryforum.com/forum/att...5&d=1189528965

An other tail-sitter:

http://www.dailymotion.com/search/h%...sonnel_extreme

International Internet Theft Ring.
 

quadrirotor,

The Austrian (OOPS make that German) pilot of the little coaxial must have gone on a diet. This time he was able to keep the craft off the ground. :)


Are you here to steal back the picture I stole from you?
Or, are you the one who just stole IFMU's X2 picture. :eek:

Dave

IFMU,

It's nice to see the X2 in the flesh at last (or was this a mockup?). Somehow it looks all innocent there, despite what it is going to achieve. I'm always amazed how a pile of parts can slowly, but magically, become a machine in the hands of talented test fitters.

I bet it's starting to look the business at Schweizer now...

Wikipedia entry..
 

http://en.wikipedia.org/wiki/Sikorsky_X2
http://upload.wikimedia.org/wikipedi.../X2_attack.JPG
:ok:

I think this one has a better handling, as she could have a vectorizing tail...


http://www.rotaryforum.com/forum/att...0&d=1194272226

What would that buy, besides a more aft CG? Consider that a rigid rotor helo has lots of control power an zero airspeed already.

-- IFMU

At an all-hands meeting, Jeff Pino claimed first flight target date is 1/15.

A bare rotorhead run was performed late last month.

Looking at those pix reminds me of the ill fated Cheyenne......too complex for what you achieve.
P.S. Jeff Pino seems to be slipping the date again...first flight was supposed to be before Christmas.

Great news! :D

Take your time guys, and make it the success it deserves to be.
Us X2 fans have waited patiently this long...

I often wonder if the people at any big aerospace company that release flight dates are in touch with the project, or are isolated from it by layers of management. Maybe this is not the case here, but I wonder.

I guess we'll find out, in another month!

-- IFMU

IFMU, i can only speak from the perspective of having been involved in the design, analysis, testing & development of many ground vehicles for various industries (it still ain't helicopters :sad:). Any particular objective date will be more a target for the engineer's to aim towards. A well run project will adjust to the development activities, but will not dictate them.

Let's face it this is a complex helicopter program, not a train timetable!

Mart;
The originally promised date was late 2006.
Perhaps the Engineering dept. should set the Engineering dept's target date. Not the Hyperbole dept.

Perhaps you recall;

Dave,

The original date communicated to subs when the program started was actually mid 2006.