Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Trent772
#1802053
Airbus speak here, the Tractor boys will have to explain their added coal switches :pirat:

As the Airbus has static throttles, i.e. during flight, they stay in a spring loaded gate, TOGA refers to Take Off Go Around.

You have Idle, Climb Flex/MCT and TOGA. Full power is limited by time, MCT is max continuous thrust (used when single engine for example).

On a normal takeoff you will pre programme an artificial OAT which reduces the takeoff power when Flex/MCT is selected. On the minibus, you would start at idle, advance the thrust levers and pause to allow the engines to spool up, then smoothly advance to the Flex/MCT detent. On the Trent A330, that is not required as the engines FADEC protects the acceleration by itself, you can go straight to Flex/MCT.

If you want all the beans, you would go to TOGA and they all arrive !

Once at acceleration altitude, You bring the thrust levers back either from TOGA or Flex/MCT to Climb where they stay for the rest of the flight and the autothrust system looks after everything.

Now, on approach, if you need to go around, by advancing the thrust levers to TOGA, it not only summons all the beans, but more importantly, sequences the flight guidance system into the go around mode, either via the flight directors or via the autopilot.
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By matthew_w100
#1802064
Trent772 wrote:On a normal takeoff you will pre programme an artificial OAT which reduces the takeoff power when Flex/MCT is selected.


I still don't understand why this is the method used. If reduced power take off is an important and regularly used flight process, why isn't there a proper auto pilot/throttle regime to support it? Surely the requirement didn't come only after all the flight control s/w had been written, necessitating what to me, the layman, looks like a work-around if not an actual bodge? Why does it accept a manual OAT anyway, instead of using, you know, a thermometer?

Also, am I being thick or is it counter-intuitive that *upping* the OAT *reduces* the power demanded? If I'm somewhere hot in my SEP I want all the power I can get!
PeteSpencer, tfin25 liked this
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By Trent772
#1802123
Pete,

Correct - TOGA is seldom used unless you are performance restricted, or there is forecast wind shear or in my case of my last flight - I simply wanted to have fun because our company was going bust.

Matthew,

The simplest way to reduce thrust on takeoff is to tell the brain it is hot outside. It does the rest. Just an easy solution. Will only reduce thrust to around 75% max, or climb thrust. Been done that way for years. Simple, foolproof, efficient.
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By Trent772
#1802124
Upping the OAT reduces the margins on the limiting temps of the engine. It therefore restricts thrust.
matthew_w100 liked this
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By Rob L
#1802128
Trent772 wrote:Airbus speak here, the Tractor boys will have to explain their added coal switches :pirat:
That doesn't help me ...what are Tractor boys and what are coal switches?

Trent772 wrote:As the Airbus has static throttles, i.e. during flight, they stay in a spring loaded gate
What is a spring loaded gate?

Trent772 wrote:TOGA refers to Take Off Go Around

Well that answered the question, eventually :wink:

To be honest, a lot of us know this, but not all. Why subject this GA forum to all this Pprune stuff. Just use a re-direct.

Rob.
Here's the rest of Trent's post , down below ↓

Trent772 wrote:...You have Idle, Climb Flex/MCT and TOGA. Full power is limited by time, MCT is max continuous thrust (used when single engine for example).

On a normal takeoff you will pre programme an artificial OAT which reduces the takeoff power when Flex/MCT is selected. On the minibus, you would start at idle, advance the thrust levers and pause to allow the engines to spool up, then smoothly advance to the Flex/MCT detent. On the Trent A330, that is not required as the engines FADEC protects the acceleration by itself, you can go straight to Flex/MCT.

If you want all the beans, you would go to TOGA and they all arrive !

Once at acceleration altitude, You bring the thrust levers back either from TOGA or Flex/MCT to Climb where they stay for the rest of the flight and the autothrust system looks after everything.

Now, on approach, if you need to go around, by advancing the thrust levers to TOGA, it not only summons all the beans, but more importantly, sequences the flight guidance system into the go around mode, either via the flight directors or via the autopilot.
klutz liked this
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By Paul_Sengupta
#1802140
As I CFIT wrote:Nothing to do with noise or fuel savings. In fact, reduced thrust take-offs and climbs actually increase total fuel burn to 'top of climb'.


But won't TOC be further down-route? It should be done in mpg...
By As I CFIT
#1802359
Paul_Sengupta wrote:
As I CFIT wrote:Nothing to do with noise or fuel savings. In fact, reduced thrust take-offs and climbs actually increase total fuel burn to 'top of climb'.


But won't TOC be further down-route? It should be done in mpg...


Reduced climb thrust prolongs the climb and delays the achievement of the higher TAS associated with high altitude flight. The most efficient way to climb a jet transport is to use full climb thrust and fly a precise speed schedule which is based on weight, OAT, wind and an airline-prescribed time/fuel cost bias which is entered into the computer.