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
remove spaces and make the obvious substitutions to reply by mail
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.

On Sep 22, 9:18*am, Stefan wrote:
Robert Moore schrieb:

A slip is a slip is a slip.
From The FAA H-8083-3a, *Airplane Flying Handbook

Ok, so in the USA there exist several different brands of slips.

In the rest of the world however, a slip is a slip is a slip. Which is
how airplanes see it, too, I suppose.

More countries than the USA see it as separate ideas. In
Canada we see things as forward or side-slipping:

http://www.tc.gc.ca/civilaviation/ge...artII/Ex15.htm
http://www.tc.gc.ca/civilaviation/ge...3723/ex15..htm

The airplane doesn't care which we are doing, and it feels no
difference in airflow. The difference is in the ground track relative
to aircraft heading, which makes all the difference to the pilot,
since he wants to meet the surface at a certain place and if he uses a
sideslip when there's no wind, he'll be in the rhubarb well off to the
side of the runway, the same place he'll end up if he uses a forward
slip when he's trying to correct for crosswind.
The Air Canada pilot was a sailplane pilot, too, familiar with
slipping, and had operated sailplanes out of Gimli so he knew the
place. If anyone else had been at the controls it might not have
turned out so pretty.
I don't know why so many pilots are afraid of slipping, and why
some aren't getting the training and testing. As you can see in the
links, Canada mandates and tests for it and we use it all the time,
even in 172Ms that make no fuss at all doing it with full flaps. 172s
have too little rudder authority to make a slip really useful, though,
and once we start the students in the Citabrias they find out what a
good slip really looks like. My Jodel with its all-flying rudder (no
fin) will slip so aggressively that it scares almost anyone, and this
in a little airplane with short wings that needs no flaps in the first
place because it descends so steeply with power off.
Canada also mandates the spin demo for private students (ours
get to perform the full entry and recovery) but it's not on the PPL
flight test; Commercial flight test candidates have to enter and
recover on command from the examiner. It's another technique too few
pilots are familiar with. We don't kill people doing it, either.

Dan

george wrote in

m:

A number of aircraft that I've flown do not have flaps and the
sideslip was an everyday common maneuver .
I found the practice was frowned upon in the modern aircraft as
there were claims that the elevators were shielded and all manner
of problems could develop


The only one I've seen with that notation was the Cessna. It wasn't
prohibited but the plane seemed to slightly porpoise when you did it.

--

"Jim Logajan" wrote in message
.. .
| Amine wrote:
| 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?
|
| Glider pilots use them on occasion for rapid descent and they are expected
| to demonstrate proficiency in them on the practical exam.

How do you maintain alignment with the tow plane?

"Bertie the Bunyip" wrote in message
...
| Amine wrote in news:18e46a13-6294-4b68-9775-
| :
|
| 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 emergency descent at velocities way above the normal limits. The
| pilot's makeshift technique was to engage a sideslip to decelerate the
| aircraft (which by then had no flaps, and only minimal hydraulics).
|
| Now I thought that sideslips (and crabs--whatever the difference
| between the two is...) were only to be used to handle crosswinds.
|
| They're different and they aren't just used for 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?
|
| PS: I have read about many cases of jetliners that had to make
| emergency descents at abnormally high speeds, but the AC143 seems the
| only one to have used the sideslip.
|
|
|
| it isn't.
|
|
| Bertie

"Bertie the Bunyip" wrote in message
...
| Robert Moore wrote in
| 2.60:
|
| Stealth Pilot wrote
| Sideslips are a very useful tool because they allow you to
| substantially increase the drag, which makes you descent like a
| plumbers toolbag, but doesnt change the forward speed. so you have no
| increased risk of stalling as you wash off the height.
|
| What you have described is the "forward slip". Although control usage
| is the same in both, a "side slip" is used to correct for a crosswind,
| and a "forward slip" is used to descend more rapidly on final without
| having the airspeed increase. If one is not landing, I suppose that it
| would just be a "slip".
|
| Airliners normally do not use either because of the increased discomfort
| caused the passengers....both being uncoordinated flight.
|
| Actually, they do. The 72 and 70 were kind of excepetions because of the
| risk of dragging a flap or pod, but most jet airliners land better in
| crosswinds when slipped.
| Even the autopilot will slip it if you're doing an autoland
|
|
|
| Bertie
|
|

You're an idiot. Stay in context dumb ass.

"Bertie the Bunyip" wrote in message
...
| Stefan wrote in news:1fb3$48d7ad48$54487392$9846
| @news.hispeed.ch:
|
| Robert Moore schrieb:
|
| What you have described is the "forward slip". Although control usage
| is the same in both, a "side slip" is used to correct for a crosswind,
| and a "forward slip" is used to descend more rapidly
|
| A slip is a slip is a slip.
|
|
| No it isn't.
|
|
| Bertie

Then how is it different, dumb ass.

"Bertie the Bunyip" wrote in message
...
| Stefan wrote in
| :
|
| Bertie the Bunyip schrieb:
|
| You're full of ****, stefan.
|
| Still better than completely hollow like you.
|
| Slips are slips no matter where you are and slips, while
| aerodynamically identical have different references.
|
| Of course they have different references... visual references, that
| is: In one, you look straight ahead, in the other, you look slightly
| to one side. I'm fully aware that this difference is enough for simple
| minded like you to think they are two different maneuvres.
|
|
| Yeah, right backpedaling boi.
|
|
| Bertie

"Bertie the Bunyip" wrote in message
...
| Stefan wrote in news:9cc9b$48d7b746$54487392
| :
|
| Robert Moore schrieb:
|
| A slip is a slip is a slip.
|
| From The FAA H-8083-3a, Airplane Flying Handbook
|
| Ok, so in the USA there exist several different brands of slips.
|
| In the rest of the world however, a slip is a slip is a slip. Which is
| how airplanes see it, too, I suppose.
|
|
| You're full of ****, stefan.
|
| Slips are slips no matter where you are and slips, while aerodynamically
| identical have different references.
|
|
|
|
|
|
| Bertie
|
|

You're full of ****. A slip is a slip, and you are a sap.

"Stefan" wrote in message
.. .
| Robert Moore schrieb:
|
| What you have described is the "forward slip". Although control usage
| is the same in both, a "side slip" is used to correct for a crosswind,
| and a "forward slip" is used to descend more rapidly
|
| A slip is a slip is a slip.
|
| I always wondered why so many flight instructors celebrate the art of
| making simple things seem complicated. I finally came to the conlusion
| that it's to look more impressive to the female students.

Cuz they have their heads up their asses, just like Bertie Buttlick.