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GlassRat
40116.  Sat Dec 17, 2005 2:41 pm Reply with quote

In the question involving chickens and Rolls-Royce gas turbine engines in the final episode of series 3, the picture in the background is not an RR engine.

All RR engines rotate clockwise when viewed from the front, but the one pictured would go anti-clockwise. The photo wasn't inverted because the blade numbers were the right way round.

It could possibly have been a V2500 (made by IAE) or a BR700 series (BMW-Rolls-Royce), both of which rotate anti-clockwise & are manufactured by RR joint ventures. Probably more likely to be a General Electric or Pratt & Witney engine, and quite an old one too, as it has clappers between the fanblades.

Your eagle-eyed rodent,
GlassRat

 
JumpingJack
40117.  Sat Dec 17, 2005 2:44 pm Reply with quote

Terrific post, GlassRat.

We will check with the Picture Elf.

 
eggshaped
40130.  Sat Dec 17, 2005 4:09 pm Reply with quote

Glassrat, if that is correct, it is by far the best QI quibble I have heard from this series.

Wonderfully geeky and eagle-eyed in equal proportions.

 
Flash
40148.  Sat Dec 17, 2005 5:05 pm Reply with quote

Is it possible that the picture was inverted, but that we were looking from the inside, outwards? I only ask.

 
GlassRat
40222.  Sun Dec 18, 2005 3:50 am Reply with quote

No, because you could see the whole of the fan and the pointy nosecone, which you wouldn't be able to see from the inside of the engine. Also, the blades would be numbered on the front.

Having slept on this, doubt starts to creep in ... the "RR engines turn clockwise" statement may only truly apply to RR engines designed and manufactured in Derby (the original RR plant). Military engines from Bristol may turn anti-clockwise, but will have been designed by (or based on designs of) the Bristol Siddely engine company, which was taken over by RR in 1966.

Then again, the birdstrike requirements are an airworthiness requirement from the civil certification authorities (EASA, FAA), which wouldn't necessarily apply to military engines, so it's not an unreasonable assumption that it should be a civil engine.

Hopefully someone will be able to put me out of my misery & tell us what it really is!

 
Gray
40224.  Sun Dec 18, 2005 4:36 am Reply with quote

Good quibble!

Does wing structure have to be designed differently to accommodate engines that turn in different directions? I.e. is there any difference in torque direction on the engine mounting, or do the internal fans rotate in different directions to make it all balance out?

Simply: if you put an anti-clockwise-turning engine on a wing designed for a clockwise-turning engine, would the wing crackup?

 
violetriga
40227.  Sun Dec 18, 2005 5:39 am Reply with quote

Jet engines are like toilet flushes - they turn the opposite way in Australia ;)

double ;)

 
djgordy
40235.  Sun Dec 18, 2005 5:55 am Reply with quote

Apparantly aero-engines manufactured in the UK turn clockwise and those made in the US turn anti-clockwise.

http://www.blonnet.com/2005/10/31/stories/2005103101830600.htm

 
GlassRat
40259.  Sun Dec 18, 2005 7:57 am Reply with quote

Quote:
Does wing structure have to be designed differently to accommodate engines that turn in different directions? I.e. is there any difference in torque direction on the engine mounting, or do the internal fans rotate in different directions to make it all balance out?

Simply: if you put an anti-clockwise-turning engine on a wing designed for a clockwise-turning engine, would the wing crackup?

Good point. Yes the pylons (where the engines attach to the aircraft) are different for clockwise & anti-clockwise engines, to account for the different stresses.

You are right again that some modern engines have contra-rotating cores that spin in the opposite direction to the fan. This cancels out some of the torque, but not all.

Finally, if you stuck a clockwise engine on a pylon designed for an anti-clockwise engine, your just asking for trouble ... not least from the commercial & legal depts of the company that supplied the original engine & want you to fit another one of theirs!

 
GlassRat
40260.  Sun Dec 18, 2005 8:01 am Reply with quote

Quote:
Jet engines are like toilet flushes - they turn the opposite way in Australia ;)

No, that would be the coriolis force.

If it happened to gas turbines, you would never get over the equator ... as soon as you got close they would start spinning the other way and push you back where you came from!

 
Gray
40644.  Mon Dec 19, 2005 2:47 pm Reply with quote

So the Earth has a large equatorial waist-band of crashed aircraft that have run out of fuel trying to escape?

 
GlassRat
40942.  Tue Dec 20, 2005 4:30 pm Reply with quote

And they tried to convince us they were just parking those aircraft in the Nevada desert. Now we know.

(Yes, I know ... just imagine it is for the sake of the joke.)

 
GlassRat
40947.  Tue Dec 20, 2005 4:34 pm Reply with quote

The photo on the show looked like one of these:
http://www.rolls-royce.com/media/gallery/defence/lrg_pegasus_8.htm
but directly from the front, with numbers on the blades.

 
tetsabb
40994.  Tue Dec 20, 2005 8:02 pm Reply with quote

Related (allegedly true, but probably another of my Urban Myths) story from my Gatwick days.

Air India were testing the windshield of an aircraft for resilience to bird strikes. They fed bird carcasses into a large gun-type arrangement.
First they tried a sparrow. It bounced off.
Next, a thrush. It bounced off.
Then a crow, which again bounced off.
Pleased with progress, they decided to go for something much larger, so a guy was sent off for a chicken.
He came back, put the chicken in the gun, and fired.
Through the windshield it went. Through the cockpit.
It finally came to rest halfway down the passenger compartment.

He had got hold of a frozen chicken........

 
Flash
40996.  Tue Dec 20, 2005 8:06 pm Reply with quote

Quote:
We looked into the frozen chicken story, which is very pervasive (mostly in a form which involves the Americans lending their cannon to a less-intelligent nation) and there's no basis for it.

post 39966

 

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