V-22 has been deployed!

[MMike]

10 of them....

http://www.philly.com/inquirer/special/iraq/20070920_Osprey_squadron_is_off_to_Iraq.html

[ire]

that is one cool looking aircraft.
http://media.philly.com/images/20070920_inq_osprey20z-a.JPG

[BurlyShirley]

deathtrap

[3D.]

I wonder how you'd land it, if one motor went down

[Zark]

I wonder how you'd land it, if one motor went down

You'd use the term "land" loosely:disgust1:

Its pretty cool from a tech perspective, but I really hope they've got the bugs worked out and training nailed. They've had some horrendous accidents already.

[ire]

I wonder how you'd land it, if one motor went down

Couldn't you cut the remaining motor and do the free rotor thing? I know helicopters can kinda land(albeit harsh) by doing that.

[ohio]

Is the plan to give them to the insurgents who will then crash and die inside them?

[ohio]

MMike, engineering question: why don't turbine engines work for this application?

[MMike]

Uhhhhh......they are turbines...I thought they were anyway...

[Toshi]

Uhhhhh......they are turbines...I thought they were anyway...

yup

http://www.fas.org/man/dod-101/sys/ac/v-22.htm

"Two 6150 shaft horsepower turboshaft engines each drive a 38 ft diameter, 3-bladed proprotor"

proprotor, hehe

[jdschall]

My wife's uncle is one of the head engineer's for the Marine Corp (he's a civilian) on this project. He's been working his fool ass off lately trying to get all the bugs out. He claims this latest version is much better than the older ones which were prone to falling out of the sky at a moments notice. I remain skeptical.

[ohio]

Uhhhhh......they are turbines...I thought they were anyway...

I mean jet vs turbo-prop

as in "why do you need a prop (or proprotor per Toshi's post)?"

[MMike]

Turbo fans are for creating thrust. Turboshafts (helicopter) and turboprops are for creating torque to turn the props/rotors

[MarinR00]

Well, they worked in "Transformers." That counts for something, right?

[Spero]

Couldn't you cut the remaining motor and do the free rotor thing? I know helicopters can kinda land(albeit harsh) by doing that.

Autorotation...that's my guess.

[ohio]

Turbo fans are for creating thrust. Turboshafts (helicopter) and turboprops are for creating torque to turn the props/rotors
... which then create thrust. Are you doing this to torture me, or am I really not asking the question the right way?

Why not use a turbofan? Helicopters use rotors for two reasons:
1) you need to the CoG to be below the point of thrust, and with only one point of thrust it couldn't be a turbofan or you'd be firing hot exhaust into your cabin (unless it was shaped like a donut... which would be super cool),
2) You use the rotor itself for directional control, so need to be able to manipulate the blades' orientations.
Those reasons are moot on the V-22. You have two points of thrust mounted above and well away from the cabin and I'm assuming the blades are fixed like any other turboprop. Aren't turbofans far more efficient (in terms of packaging size and power:weight... not sure about fuel but I would assume that too)?

[Spero]

... which then create thrust. Are you doing this to torture me, or am I really not asking the question the right way?

Why not use a turbofan? Helicopters use rotors for two reasons:
1) you need to the CoG to be below the point of thrust, and with only one point of thrust it couldn't be a turbofan or you'd be firing hot exhaust into your cabin (unless it was shaped like a donut... which would be super cool),
2) You use the rotor itself for directional control, so need to be able to manipulate the blades' orientations.
Those reasons are moot on the V-22. You have two points of thrust mounted above and well away from the cabin and I'm assuming the blades are fixed like any other turboprop. Aren't turbofans far more efficient (in terms of packaging size and power:weight... not sure about fuel but I would assume that too)?

I have no technical experience with this whatsoever, but I think the key to the v-22 is the size of the rotor blades...I don't think two turbofans would be able to support vtol on that size aircraft (though I know harriers just have directional nozzles that vector power from the powerplant(s)?).

[MMike]

Well if you want vertical take-off and the ability to hover, fans likley are not a good idea....if the thrust from the exhaust is what makes you go, that's a little sketchy to be loading in and out of the aircraft with the engines running. With rotors, it's just a little windy. Fans, you'll either get sucked into the intake, or BBQ'ed by the exhaust, and then flung 200 yards away.....

[Westy]

Aren't turbo props a lot more efficient? I'm guessing range would be drastically reduced with a turbo fan.

Using props and a chopper like swash plate they can probably control the thing in VTOL mode a lot better. With props they can balance the thrust with engine speed and prop pitch. A fan would be with throttle only, much harder. Get a good cross wind and you have to throttle up one side. A turbo fan's throttle response probably isn't fast enough to respond but altering prop pitch is.

[MikeD]

Aren't turbo props a lot more efficient? I'm guessing range would be drastically reduced with a turbo fan.

Using props and a chopper like swash plate they can probably control the thing in VTOL mode a lot better. With props they can balance the thrust with engine speed and prop pitch. A fan would be with throttle only, much harder. Get a good cross wind and you have to throttle up one side. A turbo fan's throttle response probably isn't fast enough to respond but altering prop pitch is.

I am SO glad you didn't design stuff for GI JOE.

[Westy]

I am SO glad you didn't design stuff for GI JOE.


I was too busy working on my kung fu grip back then.

[ohio]

Aren't turbo props a lot more efficient?

Isn't that what they're using?

MMike answered my question... Venting hot exhaust and thrust directly onto landing crews, boarding passengers, and carrier decks is probably not appreciated.

[MMike]

Isn't that what they're using?

MMike answered my question... Venting hot exhaust and thrust directly onto landing crews, boarding passengers, and carrier decks is probably not appreciated.

To them I say, "Suck it up Princess"

[jdschall]

http://machinedesign.com/ContentItem/57963/Longtimecoming.aspx

I reckon they spin kinda slow.

[Westy]

http://machinedesign.com/ContentItem/57963/Longtimecoming.aspx

I reckon they spin kinda slow.

333 rpm. Stupid government could have saved a bunch of money by using some ceiling fans.

[jdschall]

333 rpm. Stupid government could have saved a bunch of money by using some ceiling fans.

and if they could have just dropped it by a factor of 10, maybe Beck could have loaned them a turntable or two (and a microphone). I'm calling my wife's uncle to complain...