Flyaway manoeuvre
Join Date: Nov 2005
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For comparison, EH101 advocates a delta minus 15 pitch attitude change, whilst simultaneously cutting the sonar cable, pulling through to up to 136% Tq OEI and drooping Nr to the low 90s. NHP calling NR.
However, it was revealed after some discussion with AW, that the procedure has the following caveat: Day VMC, twin pilot assuming instantaneous pilot reaction . . . . hmmmm . . . . good luck night dipping then. There have been regular mumblings of a "modified" or "half" flyaway that is less severe in terms of attitude change. We shall see.
However, it was revealed after some discussion with AW, that the procedure has the following caveat: Day VMC, twin pilot assuming instantaneous pilot reaction . . . . hmmmm . . . . good luck night dipping then. There have been regular mumblings of a "modified" or "half" flyaway that is less severe in terms of attitude change. We shall see.
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Interesting thread, seems to following two avenues at the moment;
Flyaway is the technique developed for a specific ac to get you to the min power speed, often a compromise between acceleration and height loss. Normally a single defined manoeuvre mainly because it would be too difficult to teach multiple techniques for the infinite number of weight and environmental conditions. This technique will depend on many factors, control power, control response, ERG, etc.
What happens , lots of variables here, firstly the ideal situation is obviously one where you have enough power to transition normally. If not an ac manufacturer/test centre can conduct flyaway testing to establish height loss in the event of sudden power loss. This will normally be done using the defined flyaway technique (see above). Firstly you then need to work out intervention time (mentioned in earlier posts) this is actually the sum of two things, rotorcraft response time (time taken for the pilot to notice the engine has stopped) and pilot response time (time for the pilot to do something about it). Armed with this information testing can then take place to establish the flyaway height loss also described in earlier posts, normally Nr is used as control parameter for this and long story short, a load of flaways are flown and empirical derived data obtained for how much height is lost when you fly the standard procedure. Nowadays this data is used to prove a mathematical model which is used to publish ODM flyaway height loss charts.
So what does this actually all mean, basically the ht loss published will give you a pretty good idea of how much ht you will lose if you fly the published technique perfectly. We all know that engine failures rarely happen day VMC with a runway in front of you so the judgement call is on the pilot to consider all those variables, day/night/NVG/cliffs/mountains/tail or crosswinds etc. and add sensible margins if you can. Obviously if you fly something older with no flyaway data then best advice really is to try and establish the most efficient way to achieve min power speed, maybe asking the question of your operating authority as to why you doon't actually have this information?
what to do if you have a sudden power loss (flyaway technique)
and what happens if you have a sudden power loss (performance charts graphs, intervention times etc).
For my two penneth' worthFlyaway is the technique developed for a specific ac to get you to the min power speed, often a compromise between acceleration and height loss. Normally a single defined manoeuvre mainly because it would be too difficult to teach multiple techniques for the infinite number of weight and environmental conditions. This technique will depend on many factors, control power, control response, ERG, etc.
What happens , lots of variables here, firstly the ideal situation is obviously one where you have enough power to transition normally. If not an ac manufacturer/test centre can conduct flyaway testing to establish height loss in the event of sudden power loss. This will normally be done using the defined flyaway technique (see above). Firstly you then need to work out intervention time (mentioned in earlier posts) this is actually the sum of two things, rotorcraft response time (time taken for the pilot to notice the engine has stopped) and pilot response time (time for the pilot to do something about it). Armed with this information testing can then take place to establish the flyaway height loss also described in earlier posts, normally Nr is used as control parameter for this and long story short, a load of flaways are flown and empirical derived data obtained for how much height is lost when you fly the standard procedure. Nowadays this data is used to prove a mathematical model which is used to publish ODM flyaway height loss charts.
So what does this actually all mean, basically the ht loss published will give you a pretty good idea of how much ht you will lose if you fly the published technique perfectly. We all know that engine failures rarely happen day VMC with a runway in front of you so the judgement call is on the pilot to consider all those variables, day/night/NVG/cliffs/mountains/tail or crosswinds etc. and add sensible margins if you can. Obviously if you fly something older with no flyaway data then best advice really is to try and establish the most efficient way to achieve min power speed, maybe asking the question of your operating authority as to why you doon't actually have this information?
