Topic: Osprey gets the go ahead

[Tus-XC]

http://www.foxnews.com/story/0,2933,170742,00.html

Pentagon Approves Osprey Production
Wednesday, September 28, 2005
 
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WASHINGTON — The Pentagon (search) on Wednesday gave the go-ahead to begin full-rate production of the V-22 Osprey (search), the hybrid helicopter-airplane that the Marine Corps considers vital to the future of its air fleet.

The Osprey program has been threatened since 23 Marines died in a pair of crashes during testing in 2000.

The go-ahead to start full-scale production was approved by the Defense Acquisition Board (search).

Sen. John Cornyn (search), R-Texas, said before the official announcement that he anticipated that step.

"Full-ation military aircraft, and would be great news for our national security, our troops and the employees at Bell Helicopter," he said.

"As the military transforms to adapt to new and changing threats, this next generation of aircraft will be critical in keeping America safe and ensuring that our troops have the very best."

A joint venture of Boeing Co. (search) and Textron Inc.'s Bell Helicopter (search) unit builds the aircraft in Texas and Pennsylvania.

According to Bell, the current plans include the delivery of 360 aircraft to the Marines, 50 to the U.S. Air Force and 48 to the Navy. The total program is worth in excess of $19 billion to Bell and Textron through 2018.


"With this decision, tilt-rotor technology has come to life in a big way," said Michael A. Redenbaugh, chief executive officer of Bell Helicopter.

A December 2000 Osprey crash in North Carolina, which killed four Marines, was caused by a titanium hydraulic line that ruptured.

A crash earlier that year in Arizona killed 19 Marines and was blamed by investigators on pilot error.

The Osprey tilt-rotor aircraft can land and take off like a helicopter and fly like an airplane. Commanders say the Osprey can haul more troops and equipment farther than existing helicopters. It was designed to replace the aging helicopters in the Marine Corps fleet.


Cool plane bout time it got approval. 
 

[Capt_Bearslayer_XC]

It is only 'cool' if it works.

So far, it hasn't worked very well. 

23 dead men can attest to that.

I just hope that when my brethern are out there using these things, that more of them don't die b/c of technical incompetence.

[Matsukasi]

Tilt-a-whirl coffin.... yay

Not.

All of them should be set on fire and pushed off a mountain.

[Villa64]

Great time to have Bell stock.

First the ARH contract, now the tilt rotor.

[Tus-XC]

The plane does work, and if it wasn't for 2 things those accidents would have never happend.  The first being that it wasn't put together the way it was designed.  I can't remember all the details, but it was somthing along the lines that the manufactures didn't like some of the specifications the design (made purely on a cadd system) gave them, so they decided to change them.  The resulted in that hyrdolic line going out.  the second was simple, a stupid pilot trying to show off.  I have no clue what was going through that pilots head, but you don't do that when you don't have the expierence to handle it yet, especially in a new bird.  other than that, the plane is a good one, and extremly innovative.

[Villa64]

The accident in Arizona involved some aerodynamics that hadnt been invented yet, because they hadnt flown a tiltrotor yet to find out about them.

[Tus-XC]

Thats partially right, the vortex ring state was caused by the pilot taking the osprey in at too steep an angle of attack.

[Villa64]

My impression was that at the time, there was no limitation to the approach angle, because they didnt know that vortex ring state was going to be such a huge issue.  If that is the case, then how would the pilot know to avoid that region?

[Tus-XC]

can't remember all the specifics, else i would have said somthing however its the same concept that happens w/ helos when the hover a few feet above the ground for to long.  Essentially what happesn is you push out all air out thats beneath and you essentially just fall.  So this vortex ring state they've known about for a while.  From what i do remember though, the pilot over shoot the runway a bit and decided to bring it in steeper in order to make the landing look good in front of the generals instead of aborting and going around for a second pass.

[Villa64]

The controversy regarding vortex ring state is that although it is a known phenomenon in RW,  they still didnt know much about its effect in tilt rotor.  Vortex ring state is caused in RW when the downward speed of the rotor (read:  the whole aircraft) exceeds the speed of the induced flow as it is processed downward by the rotor system.  We are taught that the 1,2,3 rule applies:

10 kts or less airspeed
20% or more torque applied
300'/ min or greater rate of descent.

But this is in an aircraft that the rotor thrust is always applied 90 deg to the waterline of the aircraft (85 deg in an AH64, hooah).  Might be more difficult to predict the region in an aircraft where the rotor system itself is manipulated to different angles relative to the airframe, which itself is maneuvering on different vectors than straight forward.

Also, I had read that the vortex ring state was induced when the pilot pitch the nose down, causing the state to occur on the forward portion of the rotor (not sure what its called on a tiltrotor), due to the pitch down moment, combined with the high rate of descent of the aircraft.  What lift the guy had was halved by that maneuver, and increased the rate of descent to one that was unrecoverable.

I havent read about it lately, I might have the specifics wrong.

Villa