Russian carrier taking off with snow on wings
05-03-2012, 02:59 PM
#52
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Joined APC: Mar 2012
Posts: 72
Very observant of you.
What is laughable about it? Reduced thrust reduces the climb gradient somewhat, and in the event of an engine failure, it is reduced substantially. Are you really saying that having a lesser climb gradient is as safe as having a greater one? My point is that light frost has, and I quote, "has about the same impact on safety margins as a reduced thrust takeoff" (in reality, I would guess that light frost on the spoilers has no measurable effect, as the airflow is turbulent at that point anyway). Instead of responding with words like "drivel" and "laughable", how about something more substantive?
What is laughable about it? Reduced thrust reduces the climb gradient somewhat, and in the event of an engine failure, it is reduced substantially. Are you really saying that having a lesser climb gradient is as safe as having a greater one? My point is that light frost has, and I quote, "has about the same impact on safety margins as a reduced thrust takeoff" (in reality, I would guess that light frost on the spoilers has no measurable effect, as the airflow is turbulent at that point anyway). Instead of responding with words like "drivel" and "laughable", how about something more substantive?
Again, I don't know why I'm responding... I don't post anything 'substantive' to you because I have read your responses to others and they are beyond drivel... Which again leads me to my point about my suspicion that you are not a pilot.
Climb gradient with one engine out (the only time it matters) is the same with a full thrust take off and a reduced thrust take off. It would take me a couple of hours to explain the basic physics involved to a non-pilot type, but there it is. Substantive, informative, and also the last second I will waste on this ignorant topic. The Russians are lucky to have lived through that take off. The ATR was not as lucky, and apparently (no video from that one) just as ignorant.
Add an engine failure to your frosty take off scenario and maybe (doubt it) you'll rethink your position. I don't make this shtuff up... It is written in blood.
Bye.
05-03-2012, 04:57 PM
#53
Gets Weekends Off
Joined APC: Feb 2006
Position: B-737NG preferably in first class with a glass of champagne and caviar
Posts: 5,995
My answer would be "for the same reason we take other chances which are much more risky" (e.g. reduced thrust takeoffs, reserve fuel of an hour vs. two hours, using the MEL vs. fixing everything, flying at optimum altitude instead of one with more margin). It's all a risk-benefit equation, and frost that's only on the spoilers makes somewhere between virtually and absolutely no difference. Deicing fluid on the wing (or rain, for that matter) have a far bigger impact on the airflow. When we deice just because there's frost on the spoilers, we're paying hundreds of dollars to decrease the wing's aerodynamics.
Gotta say that the logic behind this train of though is extremely illogical, which is contrary to the mantra of most pilots that "Safety is paramount.".
05-03-2012, 08:18 PM
#54
Gets Weekends Off
Joined APC: May 2008
Posts: 879
If you truly were a pilot, you would have noticed that TOGA takeoffs result in a greater acceleration than you get with reduced thrust (meaning more runway to stop on if you need to), and a greater climb rate (it saves fuel to do TOGA takeoffs because you climb more rapidly). Given these FACTS, saying that you have just as much of a safety margin at reduced thrust as at TOGA is absurd.
Frost on the spoilers is invisible to the free stream, because it's hidden in the boundary layer, which is turbulent at that point.
As for the Russian crew, they may not be all that "lucky", even if they were very stupid. I'm pretty sure that the only time ice has taken down a slatted wing airplane was the SAS MD-80, and that had nothing to do with stalling.
I think the reason you don't want to continue this conversation, is you can't defend your position - you just hide behind vaguaries like "It would take me a couple of hours to explain".
Or maybe you're just trying to hook me, in which case, touche! Nicely done! People putting out bad information really gets me.
That's exactly the point - safety isn't impacted by light frost on the spoilers. If you're worried about that, then I hope you don't fly through rain. As I said, heavy rain can reduce L/D max by 30%, which is in the same ballpark as heavy frost all over the wing. Make sure you avoid rain if that truly is your mantra. And use TOGA every time too, carry 2-3 hours of contingency fuel on every flight, refuse to fly any airplane with an MEL on the GPWS/predictive windshear/yaw damper/etc, use autobrakes MAX/MED on every landing, and so on.
Last edited by FAULTPUSH; 05-03-2012 at 08:38 PM.
05-04-2012, 04:46 AM
#56
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Joined APC: Mar 2012
Posts: 72
If you truly were a pilot, you would have noticed that TOGA takeoffs result in a greater acceleration than you get with reduced thrust (meaning more runway to stop on if you need to), and a greater climb rate (it saves fuel to do TOGA takeoffs because you climb more rapidly).
WE do not calculate climb gradients based on both engines operating at flex or full thrust. WE plan on worst case for all take-offs. Again, it would take me hours to explain this to a non-aviator. Again, your 'point' is nothing more than useless drivel.
I don't explain them because WE already know what I am talking about, but because you are not a professional aviator, you need me to spell it out for you. There is no need for me to explain-- as I said before, it is good that the REST of the world does not agree with you!
It is like a sports commentator explaining how the ball going over the fence is a home run... if you are the person that needs that explanation, you are probably not watching the game to begin with.
Oh, the irony.
Bye bye again troll.
05-04-2012, 09:26 AM
#58
Gets Weekends Off
Joined APC: May 2008
Posts: 879
Yeah...I would think that someone who is serious would take the time to make their case instead of just making ad-hominem attacks.
Nice dodge. The worst case allows you to meet the climb gradient requirements at the reduced thrust settings on one engine. Ominous made the claim that "Climb gradient with one engine out ... is the same with a full thrust take off and a reduced thrust take off". That is laughable.
But back to the point at hand - light frost that is only on the spoilers is invisible to the freesteam airflow, and thus other factors have a much larger impact on safety, yet nobody loses any sleep over the other things. That is my original point.
There's a lot of things that many people take as fact that are not truly the case:
- there's no gravity in outer space (had to throw it in - it's my favorite urban legend)
- when two molecules of air separate at the leading edge to go around the wing, they meet up again at the trailing edge
- the reason performance is so substantially reduced on one engine is due to loss of induced lift (I've seen that answer taught by a GA designee)
- the "air pressure" on top of the wing is less than on the bottom.
- any frost on the wing will impact the stall angle.
- all the safety advances made in aviation save lives.
Perhaps we need a new thread for urban legends?
Last edited by FAULTPUSH; 05-04-2012 at 09:43 AM.
05-04-2012, 10:08 AM
#59
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Joined APC: Mar 2012
Posts: 72
Pity.
05-04-2012, 11:23 AM
#60
Gets Weekends Off
Joined APC: May 2008
Posts: 879
If you're a flight test engineer, I'm sure you can dumb it down to my level. Are you saying that with the higher speed that you may (will?) have on a FLEX takeoff, the increased excess power due to the higher speed compensates for the reduction in thrust, resulting in the same gradient?
BTW - I can prove I'm a pilot, with the following:
If you're at a BBQ, how can you tell which people are pilots and which are flight attendants?
1. Flight attendants are the ones eating standing up
2. Pilots are the ones who have their tray in their lap.
To which, an Airbus pilot says "Huh? I dont' get the second part." <-----------PROOF!!
Last edited by FAULTPUSH; 05-04-2012 at 11:34 AM.
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