Affect of half bank on climb gradient

[barrichello72]

Hi everyone
During my last recurrent on the 605 i was told that the usage of the 1/2 bank feature reduces the climb gradient by 0.38%: dors anybody know the reason behind it?

[Willit Run]

Think back to private pilot days and the effect of bank vs airspeed vs vert.speed..................

Generally where I come from, when you bank a plane you lose vertical lift component.

[BARKINGMAD]

Did you mean "reduced bank" INCREASES climb rate?

If so, yes it does, as you are taking less energy out of the equation to turn at the "normal" rate.

Think lift vector, induced drag and all the other ATPL groundschool science.

I used to use it frequently on 737 towards ToC as it maintained a better rate of climb whilst conforming to Lateral Nav needs.

Also, if in Hdg mode, passengers awake and looking out the window don't like it when the aircraft rolls to approx 25 AOB at high altitude, it makes them think "here we go, we're all going to die!".

If using this feature, remember to reset normal bank angle to avoid embarrassment later in the descent/approach. :)

[Naali]

If I got it right,someone else has also experienced the Wiiide tuuurn when A/P tries to catch up,with half bank on... ;).

[BizJetJock]

The increased drag due to the increased lift required to turn will always reduce the climb rate/angle. The greater the bank the greater the reduction.
For the 605, page 06-04-18 of the AFM gives you figures for 15 degrees of bank clean and flaps 20, which are 0.30 and 0.38%.
The important thing to remember is that the reason we use half bank following an engine failure is that at V2 with flaps 20 or Vt clean we do not have our normal margins above the stall, so bank should be limited to 15 degrees. Also at high level we use it for the reasons others have given. Luckily the Challenger automatically reverts as we descend or, if you've activated it lower, when you try and commence an approach.

[Mad (Flt) Scientist]

Did you mean "reduced bank" INCREASES climb rate?

Depends what you are comparing it to. The wording is vague.

The use of half bank will reduce the climb capability compared to straight-ahead capability, but will not reduce it as much as using full bank would. So it is increased compared to full bank. (And it's probably close enough to the same change as to be not worth worrying about)