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Asymmetrical thurst



 
 
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  #1  
Old March 10th 08, 11:34 PM posted to rec.aviation.ifr
Jim Carter[_1_]
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Posts: 403
Default Asymmetrical thurst

Watching the videos of the heavies crabbing to a landing in high cross winds
prompts me to ask: why don't they use asymmetrical thrust instead of
kicking it straight in the flare?

Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?

Have these techniques gone the way of the steam gauges?

  #2  
Old March 11th 08, 12:56 AM posted to rec.aviation.ifr
Matt Whiting
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Posts: 2,232
Default Asymmetrical thurst

Jim Carter wrote:
Watching the videos of the heavies crabbing to a landing in high cross winds
prompts me to ask: why don't they use asymmetrical thrust instead of
kicking it straight in the flare?


Too slow and too hard to manage.


Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?


Poor instructors.


Have these techniques gone the way of the steam gauges?


The first technique (differential thrust) never existed to my knowledge
and the second technique is alive and well with well-trained pilots.

Matt
  #3  
Old March 11th 08, 01:09 AM posted to rec.aviation.ifr
Mortimer Schnerd, RN[_2_]
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Posts: 597
Default Asymmetrical thurst

Matt Whiting wrote:
Watching the videos of the heavies crabbing to a landing in high cross winds
prompts me to ask: why don't they use asymmetrical thrust instead of
kicking it straight in the flare?


Too slow and too hard to manage.



At least in a jet. The time delay involved in spooling up probably has the most
to do with it not being currently used.


Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?


Poor instructors.


Have these techniques gone the way of the steam gauges?


The first technique (differential thrust) never existed to my knowledge
and the second technique is alive and well with well-trained pilots.



I've used differential thrust before so I know the technique exists. However I
was flying something with piston engines which essentially had instant reaction
to throttle inputs. Passengers liked it better than the more usual methods
because it presented them with a more conventional view looking out the window,
hence less anxiety. When you land on just one wheel after a successful slip to
a landing, they think you've screwed up.



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com


  #4  
Old March 11th 08, 01:16 AM posted to rec.aviation.ifr
Jay Maynard
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Posts: 521
Default Asymmetrical thurst

On 2008-03-11, Matt Whiting wrote:
Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?

Poor instructors.


Interesting...because the first CFI I flew with in 15 years had me use the
exact same technique my primary instructor taught me: point it down the
runway with the rudder, hold it over the centerline with the ailerons. I had
thought that was the standard light aircraft approach to the problem.

Have these techniques gone the way of the steam gauges?

The first technique (differential thrust) never existed to my knowledge


I wouldn't expect differential thrust to be manageable with a
turbofan/turbojet because of the time lag between throttle and thrust.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
http://www.hercules-390.org (Yes, that's me!)
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  #5  
Old March 11th 08, 03:11 AM posted to rec.aviation.ifr
Robert M. Gary
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Posts: 2,767
Default Asymmetrical thurst

On Mar 10, 4:34*pm, Jim Carter wrote:
Watching the videos of the heavies crabbing to a landing in high cross winds
prompts me to ask: why don't they use asymmetrical thrust instead of
kicking it straight in the flare?

Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?

Have these techniques gone the way of the steam gauges?


Slipping has been used for crosswind technique long before crab&kick.
The crab&kick was only made possible by the invention of the
nosewheel.

-Robert
  #6  
Old March 12th 08, 01:02 PM posted to rec.aviation.ifr
Kobra
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Posts: 119
Default Asymmetrical thurst


"Jim Carter" wrote in message
. net...
Watching the videos of the heavies crabbing to a landing in high cross
winds
prompts me to ask: why don't they use asymmetrical thrust instead of
kicking it straight in the flare?

Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?


I see no reason to pray. There's little difference in out come with the
crab technique or the forward slip. One you put the plane in a slip early
and keep constant control pressures thru-out your approach and the other you
put the plane in a crab, relax your control inputs and put the plane in a
slip in the last 10 seconds or so. Either the plane has enough rudder
authority or it doesn't in either situation. Neither is superior IMO and
definitely neither makes one a super pilot over the other. Seems to be
personal preference.

If you are proficient at one of these techniques you've got it covered. I
don't think that there is any situation when one of these crosswind landing
techniques is the preferred and only safe way to land over the other.

Kobra


  #7  
Old March 12th 08, 02:55 PM posted to rec.aviation.ifr
Mortimer Schnerd, RN[_2_]
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Posts: 597
Default Asymmetrical thrust

Kobra wrote:
Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?


I see no reason to pray. There's little difference in out come with the
crab technique or the forward slip.




There is one reason you should always pray: the wind is seldom a constant. As
you're coming in on short final and the wind rapidly shifts, will it happen at
the worst possible time? Will it do something so violent as to be totally
unexpected and leaving you no time to recover? *That's* why you should pray.

I can recall what started as a normal but gusty landing in a Cherokee Six. I
touched down acceptably and rolled a couple of hundred feet, then found myself
flying again; only this time I was cocked into the wind at about a 40 degree
angle to the runway at an altitude of about 2 feet. I had been rolling so far
after my touchdown that I had completely relaxed; all that was left to do was
taxi. Heh heh... the wind had other ideas. I firewalled it and managed to keep
from coming down sideways. *That's* the kind of stuff that causes me to pray at
hinky moments.



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com


  #8  
Old March 12th 08, 09:22 PM posted to rec.aviation.ifr
Stubby[_2_]
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Posts: 6
Default Asymmetrical thurst

A B-52 pilot told me part of the approach setup was to dial in the right
angle for the landing gear so a crab would be possible while the plane was
rolling straight down the runway.

"Kobra" wrote in message
. ..

"Jim Carter" wrote in message
. net...
Watching the videos of the heavies crabbing to a landing in high cross
winds
prompts me to ask: why don't they use asymmetrical thrust instead of
kicking it straight in the flare?

Even in a single, why don't we see more forward slips to a landing

instead
of crab, kick, and pray?


I see no reason to pray. There's little difference in out come with the
crab technique or the forward slip. One you put the plane in a slip early
and keep constant control pressures thru-out your approach and the other

you
put the plane in a crab, relax your control inputs and put the plane in a
slip in the last 10 seconds or so. Either the plane has enough rudder
authority or it doesn't in either situation. Neither is superior IMO and
definitely neither makes one a super pilot over the other. Seems to be
personal preference.

If you are proficient at one of these techniques you've got it covered. I
don't think that there is any situation when one of these crosswind

landing
techniques is the preferred and only safe way to land over the other.

Kobra




  #9  
Old March 19th 08, 02:28 PM posted to rec.aviation.ifr
Sam Spade
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Posts: 1,326
Default Asymmetrical thurst

Jim Carter wrote:
Watching the videos of the heavies crabbing to a landing in high cross winds
prompts me to ask: why don't they use asymmetrical thrust instead of
kicking it straight in the flare?

Even in a single, why don't we see more forward slips to a landing instead
of crab, kick, and pray?

Have these techniques gone the way of the steam gauges?


Using differential thrust would be asking for disaster.

The proper technique is fly the crab just as you would do an an ILS
localizer to remain on course during a crosswind. It is not a crab;
rather, a coordinated flight wind correction (track vs heading.

Then, as the flare begins down aileron is placed into the wind as the
opposite rudder is used to align the nose with the runway. If down
correctly, the wings remain level as the aircraft touches down, thus
preventing an engine pod from scraping the runway.

It wasn't always taught this way, but has since at least 1980, or so.
It had to be demonstrated on rating rides in the simulator with maximum
certified crosswind for the airplane.
 




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