PDA

View Full Version : Flygprestanda Optimised Takeoff data


lost soul
14th Jul 2002, 10:30
I have recently joined a company that use FP Optimised T/O data in their 737 operation but I have been unable to obtain a decent "preface" which explains all or some of the oddities of this system. In particular why some airfields seem to gain nothing from the use of Bleeds-Off performance! The normal ban on use of reduced thrust takeoffs when using Improved Climb also seems not to exist. Anyone got any good notes on this??

Checkboard
15th Jul 2002, 04:08
You use improved climb to maximise your uplift from a particular runway - obviously if that is your aim, you aren't going to used reduced thrust! It isn't a "ban" as such - more like common sense.

mutt
15th Jul 2002, 04:26
Checkboard,

Your logic is correct if you are using "improved climb" as a way of increasing takeoff weight.

"Optimized V-speed Takeoff Charts" are a different animal altogether, in this case there is nothing stopping you from using assumed temperature or a derated thrust with "improved climb".

Lost Soul,

Paste the "offending" parts of the chart on here and we can have a guess at it.

Cheers

Mutt.

411A
15th Jul 2002, 05:24
Hmmm, wonder if this is the "overspeed takeoff" that was used on certain runways (rny 16, ZRH for example) with Boeing and Lockheed aircraft.

lost soul
15th Jul 2002, 05:47
Checkboard and 411A-- it is obvious from your comments that you have never seen these types of charts-- very different from the usual "single flap setting" performance charts used by most airlines. The usual rules do NOT apply. Often ONLY "improved climb" is offered for example. Each page can have multiple flap settings depending what is computed to be the optimum flap for that temp/wind/runway combination.
411A "improved climb" is what you refer to as an overspeed takeoff where excess TODA is used to accelerate the aircraft to a higher speed to improve the gradient in the initial climb. It can result in MUCH higher speeds than usual.
Mutt- I will try and get a copy to show you-- it may take a day or two! Meanwhile if anyone else out there is actually familiar with these strange things maybe they can add their thoughts!

mutt
15th Jul 2002, 05:48
Overspeed, Improved Climb, Optimized V-speeds, they are different names for the same thing, using the excess field length to increase your takeoff speed and therefore increase your climb gradient/weight.

The only difference is that the first two are only used when they are needed, optimized V-speeds utilize this excess runway length all the time.

Mutt.

ironbutt57
15th Jul 2002, 21:55
Lostsoul...we recently changed from Jeppesen to the above mentioned charts...have also noticed many differences RE: bleeds off take-off effect on the climb-limit weight...seems these charts are much more "refined" where as the previous ones used were "coarse" so to speak....I do prefer the new charts...but they are in deed "more detailed"....the overspeed/improved climb call it what you like shortens the acceleration(level off) sector, thus improving the overall gradient to 1500' agl

lost soul
15th Jul 2002, 22:12
Ironbutt! Thanks for your comments-- was starting to think that I was the only person that had seen these-- what I am looking for is a "preface" to these charts. My company seems not to have much expanded info on them and emailing Flygprestanda produced absolutely no results! Have you access to any notes or decodes for some of the more obscure details? I struck a situation recently where operating out of a tricky airport in Nth Scandinavia-- lots of obstacles-- and the Bleeds Off correction was nil! Can't see how that could be true??
For those who have never seen these charts- quite different from the usual Jeppeson type (Single Flap config) charts-- have a look here.Optimised Takeoff Perf (http://www.flygp.se/sturup.htm)

Techman
15th Jul 2002, 23:40
I used to work with these charts many moons ago.

Might still have the preface you are talking about tucked away somewhere. I'll get back to you after I have looked through all my boxes of 'stuff'.

mutt
16th Jul 2002, 03:56
Lost Soul,

That chart is for an Airbus...... you never said that you were going to talk about Airbus............... Aghhhhhh :):):)



Mutt.

411A
16th Jul 2002, 04:27
lost soul
"Much higher" speeds, you say? Hmmm, four knots does not seem all that much higher to me, but then again from an Airbooos perspective, maybe so.:rolleyes:

lost soul
16th Jul 2002, 05:20
I'm using these charts on 737-300's-- the only web example I coud find was the Airbus one. On the 737 Improved Clmb pages the speed increases are MUCH higher and often there will be up to 3 different flap settings on the one page!

mutt
16th Jul 2002, 07:36
411A,

Would you feel happier if I showed you a chart with a 35 kt speed increase for a 5 degree increase in temperature...... :):)

Lost Soul,

Boeing charts are normally produced using a program called Standard Takeoff Analysis Software (STAS), I looked through all of the outputs available and your chart isnít one of the standard outputs. So I cant help you with an explanation :(

Flygprestanda on the other hand, should not only be able to give you a detailed explanation of each and every figure on those charts, they should be able to justify the weights and speeds with calculations from the AFM!

Mutt.

[email protected]

lost soul
16th Jul 2002, 20:07
Thanks everyone for your inputs- I (We) have at last managed to get Flyprestanda to come up with an explanation of their charts- after about six months of unanswered emails! By next week I will know a lot more about this rather unusual product!

411A
16th Jul 2002, 21:36
Well, at least they DID answer. Jeppesen on the other hand, usually NEVER does.

mutt
17th Jul 2002, 04:15
411A,

Cant agree with you on this, we have a 1 working day turnaround on emails to Jeppesen, they have never failed to answer one of my questions.

But there again, I do work for a real airline! :):)

Lost Soul,

I'm glad to see that you got an answer, please reveal all next week.


Mutt.

ironbutt57
17th Jul 2002, 18:47
why would u need takeoff charts from jepp for a cessna 411?:D

411A
18th Jul 2002, 03:10
Not for the 411, Ironbutt, the JetStar.