Windmills or windturbines? There's a difference. In Delft we have 1 windmill and a few windturbines around the Technische Universiteit.

Windturbines yes, sorry.

- windmilling does NOT produce energy. Its is simply the first stage (N1) compressor blades spinning due to wind blowing across them.

something I always wondered about seeing engines windmill is does it not cause extra wear and tear having an engine slowly turning with no Oil pump/Oil Pressure to keep it lubricated? I know its only turning slow but its still metal + metal

It's what a windmill does. Engines do the same if there is enough wind.Look here. Cheers.

You never asked a question on these forums without going to google first?

something I always wondered about seeing engines windmill is does it not cause extra wear and tear having an engine slowly turning with no Oil pump/Oil Pressure to keep it lubricated? I know its only turning slow but its still metal + metal

Im guessing whatever the fan is connected to - some sort of shaft (no sexual innuendo implied...) is lubricated so it can spin freely.Im guessing the noise it makes is to warn ground grew that the turbine is spinning which I'm guessing if something did get drawn into it by the wind cause some minor damage to the fan blades themselves, or a moor extreme example of someone sticking their hand into the fan blades and even at that speed could cut it clean off.Cheers,Tim

Im guessing whatever the fan is connected to - some sort of shaft (no sexual innuendo implied...) is lubricated so it can spin freely.Im guessing the noise it makes is to warn ground grew that the turbine is spinning which I'm guessing if something did get drawn into it by the wind cause some minor damage to the fan blades themselves, or a moor extreme example of someone sticking their hand into the fan blades and even at that speed could cut it clean off.Cheers,Tim

I'm in training on the 737, but I flew the 727 for a while which had the old JT8D engines. I'm assuming the noise the CFM56 makes when windmilling is the same that the JT8D made, though I suppose I could be wrong, but what caused that was actually the fan blades. Click here to see that the base of a fan blade is shaped so that it fits into a slot (ignore the arrow and mid-span shroud - just look at the base of the blade). When the fan stage is just windmilling, the blade has a little room in the slot, so as it rotates, it makes a clinking sound. But don't worry, there is no grinding metal as it windmills.David Lynn

David,Ahh ok that makes sense.I was watching a documentary on Rolls Royce making their turbofan engines and they showed the gap and it is literally nanometers. I just thought it would of been more of a safety feature but i guess that seems to be a by-product... Unless you hear it so much you stop listening. Cheers,Tim

Inflight if a turbine engine fails and is still windmilling (assuming it doesn't seize when it fails) it will produce some benefits. The core will windmill at a considerable speed which will be turning the accessory gearbox. So you will get some residual hydraulic power. If the engine failure was due to a flameout from weather or an interuption of the fuel flow, the engine can be relit by simply reintroducing fuel and ignition. The starter isn't required. There are minimum N2 speeds listed in the checklist for an inflight restart. The checklist will usually tell you a minimum speed to fly at various altitudes to achieve the N2 speed for a restart without starter assistance. If the N2 is below the minimum you will use the starter just like a normal start on the ground. It's all layed out in the abnormal checklists. Hiram Hunt

something I always wondered about seeing engines windmill is does it not cause extra wear and tear having an engine slowly turning with no Oil pump/Oil Pressure to keep it lubricated? I know its only turning slow but its still metal + metal

Not really- the Engineers took that into account. There are very very high precision bearings on the spools and shafts. Not to mention they are very well lubricated.Little or no wear.

You never asked a question on these forums without going to google first?

Nope. I even google what I'll have for lunch every day. I can't live without Google. But what does it matter to you?

I'm in training on the 737, but I flew the 727 for a while which had the old JT8D engines. I'm assuming the noise the CFM56 makes when windmilling is the same that the JT8D made, though I suppose I could be wrong, but what caused that was actually the fan blades. Click here to see that the base of a fan blade is shaped so that it fits into a slot (ignore the arrow and mid-span shroud - just look at the base of the blade). When the fan stage is just windmilling, the blade has a little room in the slot, so as it rotates, it makes a clinking sound. But don't worry, there is no grinding metal as it windmills.David Lynn

Is this the sound you were talking about?http://www.youtube.com/watch?v=qv0sBTvpcOgOf course this is someones privately owned RB211...and it was not currently serviceable at the time the video was shot...but you get the general idea!Cheers,

Of course this is someones privately owned RB211...and it was not currently serviceable at the time the video was shot...but you get the general idea!

For some reason, instead of thinking this person needs help, i'm actually a bit jealous.

It's what a windmill does. Engines do the same if there is enough wind.Look here. Cheers.

Oh that, I saw it last week when I was passed on the highway at Schiphol.I saw the engines were windmilling. I thought the engines was running, but it wasn't :Drooling:So that was meeting the windmilling.Is the sound of windmiling also made in the NGX?

Is this the sound you were talking about?

Of course this is someones privately owned RB211...and it was not currently serviceable at the time the video was shot...but you get the general idea!Cheers,

my bike makes the same noise when I'm cycling on my bike, time to buy a new bike for me buddy!

Cmon your dutch! You should know :(

I thought there were talking about to build a windmill in the NGX or something like that! (joking):Party:No cheating on the NGX please :(

Lol guys, I'm not joking but I live in the polder here and if you take off from Lelystad - EHLE, you see a "sea of windmills" I'm not exaggerating but I think you will see a few hundred's of windmills

I believe him too, I saw it with my own eyes

If it is windmilling fairly fast a CFM-56 will make a similar sound, Handy video of the CFM-56 and how it works:http://www.youtube.com/watch?v=nSQzvimD3cc&feature=relatedAl

Is this the sound you were talking about?

Of course this is someones privately owned RB211...and it was not currently serviceable at the time the video was shot...but you get the general idea!Cheers,

Yep, that's the sound.David Lynn