Fbm3rd From United States of America, joined Mar 2005, 162 posts, RR: 0 Posted (6 years 1 month 2 weeks 4 hours ago) and read 2237 times:
Check out the pic... The caption says that the engine is being blown in the wind. But if that were not the caption, I would have thought the engine was on. So my question is, what part of the engine is NOT moving that would be moving had the engine be on and moving???
Corey07850 From United States of America, joined Feb 2004, 2500 posts, RR: 5 Reply 1, posted (6 years 1 month 2 weeks 4 hours ago) and read 2219 times:
Quoting Fbm3rd (Thread starter): Check out the pic... The caption says that the engine is being blown in the wind. But if that were not the caption, I would have thought the engine was on. So my question is, what part of the engine is NOT moving that would be moving had the engine be on and moving???
Nothing that you could see from the picture except for maybe the heat from the exhaust, and maybe the photographer being sucked into the engine
320tech From Turks and Caicos Islands, joined May 2004, 479 posts, RR: 5 Reply 4, posted (6 years 1 month 2 weeks 4 hours ago) and read 2164 times:
The caption states that it's an 8 second exposure. The fan has made more than one rev in that time, so I would say it's not possible to estimate how fast the fan was turning.
The only obvious thing that says to me that the engine isn't running, is the lack of heat out of the exhaust. Everything else looks like it could be running.
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
Sfomb67 From United States of America, joined Dec 2005, 416 posts, RR: 0 Reply 5, posted (6 years 1 month 2 weeks 3 hours ago) and read 2117 times:
Generally engines windmilling will have the midspan shrouds clanking, and you can usually see that the first stage fan is not up to speed. If you can't tell, and/or don't know for sure, STAY CLEAR.
As far as some parts not turning, yes there are, but you can't see them. Do not rely on trying to see them.
SapphireLHR From United Kingdom, joined Mar 2006, 103 posts, RR: 0 Reply 9, posted (6 years 1 month 1 week 6 days 14 hours ago) and read 1675 times:
Quoting 320tech (Reply 4): The only obvious thing that says to me that the engine isn't running, is the lack of heat out of the exhaust. Everything else looks like it could be running.
Anti Collision lights on ?? The only true verification that the engine is or is not running under power.
MtnWest1979 From United States of America, joined Nov 2005, 1976 posts, RR: 2 Reply 10, posted (6 years 1 month 1 week 6 days 12 hours ago) and read 1563 times:
Quoting Viv (Reply 6): The engine IS moving. Just not under its own power.
Actually, only the fan is moving, not the engine.
Also, if one was there looking at it live, the direction of the fan movement could also indicate. Spins backwards if the wind is coming from behind.
M404 From United States of America, joined Nov 2003, 2191 posts, RR: 5 Reply 11, posted (6 years 1 month 1 week 6 days 6 hours ago) and read 1375 times:
Most times I've been near a windmilling engine you will hear a very obvious clicking that is not there when under power. I'd love a technical answer to what that sound is as have only heard generalities. Something to do with the blades. Also the beacon lights should be on if under power.
Less sarcasm and more thought equal better understanding
Corey07850 From United States of America, joined Feb 2004, 2500 posts, RR: 5 Reply 12, posted (6 years 1 month 1 week 6 days 6 hours ago) and read 1340 times:
Quoting M404 (Reply 11): Most times I've been near a windmilling engine you will hear a very obvious clicking that is not there when under power. I'd love a technical answer to what that sound is as have only heard generalities. Something to do with the blades. Also the beacon lights should be on if under power.
The individual blades are not solidly mounted on the compressor or turbine wheel so they can expand and contract with the heat of the engine. Essentially each blade is "loose" and when the engine is spinning the centrifugal force locks the blade into place. When the engine is windmilling imagine the blade at the 12 o'clock position resting on the wheel due to gravity... As it rotates toward the 6 o'clock position the blade "falls" the short distance engineered in for expansion...This metal to metal contact is what causes the clanking sound
Lehpron From United States of America, joined Jul 2001, 7028 posts, RR: 25 Reply 13, posted (6 years 1 month 1 week 6 days 5 hours ago) and read 1277 times:
Quoting Viv (Reply 8): A slow shutter speed makes the compressor blades appear blurred.
Those are the main bypass turbofans, the compressor blades are deep inside, sorry to nitpick.
The meaning of life is curiosity; we were put on this planet to explore opportunities.
M404 From United States of America, joined Nov 2003, 2191 posts, RR: 5 Reply 14, posted (6 years 1 month 1 week 5 days 21 hours ago) and read 1155 times:
Corey - Thanks a bunch. OK, I had it right - heat expansion spacing in the blade mounts. Finally I got confirmation. Could not get the illustration - said I wasn't authorized. Oh well, as long as I can get into employee parking - - -
Less sarcasm and more thought equal better understanding
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