high altitude engine performance

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high altitude engine performance

Postby Brian Z » Fri Apr 19, 2013 7:30 pm

Not sure if this is the right topic to post under, but I have an addon aircraft that seems to lose too much thrust as it climbs, Posky ERJ-135ER. What number would I change, and which way, to try to fix this? According to the information it comes with, typical cruise is 0.78 mach at 35,000. At 35,000, it will only do 0.74, with the throttles wide open. At takeoff though, it seems to perform the way it should, it just loses power too quickly as altitude increases.
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Re: high altitude engine performance

Postby Gringo6 » Mon Nov 18, 2013 4:26 pm

Is the auto throttle turned on? Sometimes the rpm is set too low when in auto throttle. This can be fixed if it is the problem by a change in the aircraft file.

Suggest you turn the A-T off and see if thrust increases
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Re: high altitude engine performance

Postby Brian Z » Mon Nov 18, 2013 5:41 pm

Nope, autothrottle is off. At takeoff it acts just like any other default/freeware jet-- you have to back off a lot after retracting gear and flaps, so that the engines don't kill you. Once you start getting high up the engine performance seems to drop way off.
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Re: high altitude engine performance

Postby Russell Irwin » Mon Nov 18, 2013 7:59 pm

I'm not sure if this will help, but if I were you I'd change my throttle climb settings.

1. Try a flex takeoff, i.e. take off with only 75% power (varies, depending on temperature, aircraft weight, runway length, etc.)

2. Do not adjust your throttles during climb unless necessary. Instead, set your IAS bug to 250 KIAS and climb at an angle so that you maintain 250. Once you get to 10,000 feet, adjust this to 320 KIAS. You shouldn't have to adjust your throttles until at least 20,000.

I've seen this problem with another aircraft (Project Airbus A321), and the forum there suggested that I adjust climb settings. In fact, this has worked so well for me that I use it on all flights now. I don't know if it will help you, but I think that it will.
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Re: high altitude engine performance

Postby Fozzer » Sun Dec 01, 2013 11:03 am

Although it doesn't apply to commercial jet engines and fuel-injected piston engines, in my normally aspirated carburettor piston engines I take great care in adjusting the "Mixture" strength to obtain the highest Exhaust Gas Temperature, and therefore the maximum power, once over 5,000 feet Above Sea Level.
Very important to obtain maximum power when flying at high altitude, and high altitude airstrips, in my Cessna 150/152, etc,... http://www.airliners.net/aviation-forum ... in/219830/

Paul...FS 2004+FSX...and fiddling with the Mixture Control... :mrgreen: ...!

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