Crab, slips, and crossed controls

On Sep 22, 5:37*pm, "Capt. Geoffrey Thorpe" The Sea Hawk @See My
Sig.com wrote:
"Amine" wrote in message

...

Hey,

Some of you may have heard of Air Canada 143 [http://www.youtube.com/
watch?v=dfJIpA2gv1g] which ran out of fuel in mid air and had to make
an .

Oh, the Gimli Glider...

The

pilot's makeshift technique was to engage a sideslip to decelerate the
aircraft (which by then had no flaps, and only minimal hydraulics).

Ok, I wouldn't describe it as a "emergency descent at velocities way above
the normal limits" - they were trying to glide into a former airport for a
landing. Since they didn't have any flaps, they had to come in faster than
usual and the pilot used a slip to control the glide angle (not decelerate)
since he didn't have flaps / spoilers / power to work with.
Nothing makeshift about that.



Now I thought that sideslips (and crabs--whatever the difference
between the two is...) were only to be used to handle crosswinds. I
didn't read anywhere that they could be used to bleed excessive speed,
although it makes sense from an aerodynamics perspective. Anyone out
there used sideslips for anything other than crosswind approaches?

It was used in this case to control the glide angle - a typical thing to do
in aircraft without flaps and sometimes a handy tool if you do have flaps..
I used to fly a Cessna 120 which didn't have flaps - I would slip in to a
landing more often than not.

But a very aggessive side slip tend to be uncomfortable for passengers.

--
Geoff
The Sea Hawk at Wow Way d0t Com
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When immigration is outlawed, only outlaws will immigrate.

Many air show pilots use a slip to simply scrub off some altitude or
airspeed entering a show line if the entry is a bit high or fast or
both. I usually employed this in the entry turn which was almost
always a descending turn into the show line. It's quite common to see
pilots of high performance tail wheel airplanes like a Pitts for
example, using a slipping turn onto final approach, then holding in
the slip correcting the turn into a slipping transition to a short
straight slipping final.
I like to think of slips not so much as a maneuver per se, but simply
an application of diliberate crossing of controls to achieve a
specific result from the airplane. In other words, a slip should be
considered as much of the pilot's normal control application as any so
called "coordinated" input of controls.