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By: - 24th January 2005 at 14:32 Permalink - Edited 1st January 1970 at 01:00
I believe it is to prevent the engines from being damaged by thermal shock. They run them for 2.5 minutes at an intermediate power setting, to allow the internal engine temperatures to stabalise, then a similar amount of time at takeoff power for the same reason. I think I read this in 'Flight Intl' some time ago.
There is a great deal of research & development that goes into maintaining the correct temperatures & clearances inside a modern jet engine. I think it is fair to say that the Russians are still in the early stages with their high bypass turbofan engines.
By: - 24th January 2005 at 19:12 Permalink - Edited 1st January 1970 at 01:00
HP81 is correct in his answer, we may also get over this prob with the Zap engine coming shortly so I am lead to believe..
A225HVY
By: - 24th January 2005 at 21:52 Permalink - Edited 1st January 1970 at 01:00
Thanks for the replies and info fellas. :)
-Dazza
By: - 24th January 2005 at 21:58 Permalink - Edited 1st January 1970 at 01:00
I believe it is to prevent the engines from being damaged by thermal shock. They run them for 2.5 minutes at an intermediate power setting, to allow the internal engine temperatures to stabalise, then a similar amount of time at takeoff power for the same reason. I think I read this in 'Flight Intl' some time ago.
There is a great deal of research & development that goes into maintaining the correct temperatures & clearances inside a modern jet engine. I think it is fair to say that the Russians are still in the early stages with their high bypass turbofan engines.
An AN124 at PIK yesterday told ATC "we will need the usual 4 minutes on the runway before departure."
By: - 28th January 2005 at 16:55 Permalink - Edited 1st January 1970 at 01:00
Libyan AN124 5ADKL due in STN on Sat 1900z dep 2100z
A225HVY
By: - 31st January 2005 at 13:58 Permalink - Edited 1st January 1970 at 01:00
My mate who used to be a controller at STN said that this run up was a nightmare as it effectively closed off the airport for several minutes at a time as these power settings had to be set on the runway. It also did no favours with the locals due to noise.
By: - 31st January 2005 at 15:36 Permalink - Edited 1st January 1970 at 01:00
Stuff the locals!!
All the aircraft are ICAO chapter III noise certified no probs there
A225Hvy
By: - 2nd February 2005 at 16:16 Permalink - Edited 1st January 1970 at 01:00
You can also cheat on those tests! If there's a noise recorder somewhere beneath the flight path on climb out, designed to record the noise level of the aircraft flying overhead, the pilot can throttle up to use high thrust to get airborne, then throttle back to reduce the noise over the recorder, then throttle up again to continue climbing.
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By: Dazza - 23rd January 2005 at 00:09
I was up at EMA tonight and was fortunate enough to get there in time to see an AN-124 depart, as usual once lined up on 09 the engines were run at two different power settings for several minutes before commencing its take-off run. Why do these heavies have to do this? I've never found a definitive answer so I thought I'd ask you learned folk! :)
-Dazza