Some questions relating to winglets and speeds of the Boeing 777.

Some questions relating to winglets and speeds of the Boeing 777.

Flying Flying on the Boeing 777
Tuesday, 11 December 2007 20:51

Dear Captain Lim,

Thanks for answering my previous questions. I have an interview with Cathay Pacific coming up shortly. So all the help I can get will be appreciated.

On the winglets, approximately how much drag do they reduce in terms of percentage?
What is the difference between maximum range cruise and long range cruise?
What is the relationship of V1, VR and V2?

I really appreciate your time and concern.

Thanks,

Zakk

Hi Zakk,

1. On winglets, they can reduce the drag by as much as 20 % on some wings but you can do further researches on them. I will give you all the links below:-

www.aviationpartnersboeing.com

www.b737.org.uk/winglets.htm

www.visionengineer.com/aero/winglet.shtml

www.airspacemag.com/asm/mag/index/2001/as/htww.html

www.fluent.com/about/news/newsletters/01v10i1/a2.htm

2. Very briefly, maximum range cruise gives the best range in the power setting to achieve the furthest distance with the available fuel you have on board the airplane. It is used when the pilot realized that the airplane is low on fuel. It is based on zero Cost Index.

Long range cruise is the power setting in the Flight Management Computer (FMC) which gives the best cruising speed for long range. It is based on the speed which gives 99 % of maximum fuel mileage at zero wind. This power setting is used to good advantage if you have a favorable tail wind.

3. V1 is the Takeoff Decision Speed used as a reference in deciding whether a take off is to be continued or aborted when an engine failure occurs.  VR or Rotation Speed is the airspeed when the pilot begins to rotate the aircraft to lift off attitude, normally at the rate of 2 to 3 degrees per seconds, depending on the aircraft certification.

V2 is the Takeoff Safety and Initial Climb Speed. This speed is achieved prior to 35 feet above ground level. It is attained as a result of proper rotation and lift off procedures. It allows the aircraft to maintain a specified gradient in the climb-out flight path.

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