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Guest Murf

Thrust Reduction

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Guest Murf

Hi folks,Is there a formula or table that can be used to calculate the appropriate assumed temperature for thrust reduction? I realize there are a lot of variables considered (RWY, TEMP, GW, etc) but I would like to be performing this properly instead of just using a guess.Thanks,

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Guest wkzzo

Murf, what is used is something called a flight planning and performance manual, they are specific to aircraft, engine spec and operator .I know of know formula that would cover every different engine spec and customer option. I thought someone had written an excel document that calculated fuel loads and other specifics but Im not sure if it calculated thrust requirements. Sorry cant be of more help.

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Guest Murf

Thanks for the reply Wallace!As you state these values are airline specific but it would be nice if there was some sort of general table that could be used. When a derated takeoff would normally be used I have just been taking a shot in the dark at the assumed temperature, but like everyone else here striving for maximum realism I'd like to be able to come closer to the RW values.Thanks again,

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Guest wkzzo

I guess I should have stated that the QRH's supplied with the specific aircraft also have this information Murf.

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Guest HepburnUGA

Hey Wallace,I have been looking around the Internet for the past few weeks looking for an NG QRH and can't seem to find one (probably for good reason :) ). Can you send me a PM if you know of a good source from which to acquire one?Take care,

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Guest wkzzo

Sorry Jeff ,I wouldn't know where to find one for private use. You might try Bill Bulfers site, I dont know if his cockpit companion guide covers any of that kind of info though. http://www.fmcguide.com/

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Guest HepburnUGA

Understood, I just thought it couldn't hurt to ask. Any chance of a photocopy of that assumed temperature calc. page? I could probably throw together a quick spreadsheet to calculate this if I had the info.Thanks!

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Guest wee_davie_2612

To manually calculate the assumed temperature for a derated thrust takeoff requires a Runway Analysis (aka Takeoff weight) chart. An example taken from a 737 Flight manual is shown below:http://forums.avsim.net/user_files/70578.jpgFrom this, assumed temperature settings can be found as can Climb Limited Weights for the reduced thrust. You can't use this method for contaminated runways thoughThere's not much you can do in FS to copy this procedure unfotunatley.If you want I can post the pages from the Flight manual that describe how to use this sheet and perform the calculations.CheersDavidP.s. The airline, whos flight manual I have a copy of, uses a program called ACCULOAD that is far more accurate in calculating these temps and limitations, it'll also calculate for packs on/off, contaminated runways and a bunch of other variables. Here's the blurb: http://forums.avsim.net/user_files/70579.jpg

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Guest wkzzo

If it was up to me I would gladly do it Jeff, But its proprietary documentation, so unfortunatly I cannot.

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