slips and skids

[JW Scud]

Any aerodynamic experts out there?


Is this true?


SLIP: Reduces stall speed, lots of warning prior to stall, stall results in rolling motion towards wings level attitude.


SKID: Higher stall speed, very little to no warning prior to stall, stall results in a roll toward inverted attitude.


Thanks

[Colonel]

I frequently use a 90 degree banked side-slip on short final.

In that condition:

a) what is the AOA?
b) what is my stall speed?

Ask any TC Inspector for the answers.  They know everything.

[cgzro]

In a slip the high wing is at a greater angle of attack and therefore it stalls first and will bring you through wings level giving you more time to stop it before it takes you upside down.


In a skid, the low wing is at a greater angle of attack and therefore it stalls first and will take you through knife edge etc. while you are trying to figure it out.


As to the increased or decreased stall speeds I suspect that is airframe dependent, but no doubt others will give you an exact answer. One thing to consider however is that the ASI is not going to be all that accurate as you start to present the static port to the oncoming slipstream so knowing your exact airspeed to know the difference could prove problematic.


This is why its infinitely safer to do a steep co-ordinated turn or slipping turn to final but a shallow banked skidding turn to final is extremely unwise.


This is usually lesson number one in an unusual attitude course.

[Slick Goodlin]

[quote author=Colonel Sanders link=topic=5561.msg14545#msg14545 date=1486184969]
I frequently use a 90 degree banked side-slip on short final.

In that condition:

a) what is the AOA?
b) what is my stall speed?

Ask any TC Inspector for the answers.  They know everything.
[/quote]
Funny you should mention that scenario, my Class II instructor ride hung on the answer to that in the debrief.  I forget how it came up in the first place.

[David MacRay]

I would like to discuss something related but don't know if I have the time and energy to do it here in text.

Many moons ago, remote control radios for model airplanes were expensive and extra channels even more so. Some people flew two channel radios. That meant, setting the throttle by set screw and throwing the plane airborne, then having only elevator and rudder.

How would you like to fly like that? All turns would just be skids and you would probably fly it out of fuel to glide in dead stick for landing.

Maybe that was easier than I was expecting.  :P

[Colonel]

[quote]Funny you should mention that scenario, my Class II instructor ride hung on the answer to that in the debrief[/quote]

Do tell what the TC Inspector said.  I suspect
he got it wrong.  It's a trick question, which is
all that TC ever seems to ask, so it seems fair
that any TC Inspector answer it.

[cgzro]

The proper answer to that question is to ask if they want the wings AOA and stall speed or the fuse's.

[Colonel]

Exactly.  If someone referred to AOA of a normal
wings-level aircraft on final, would they be referring
to the AOA of the vertical fin and rudder?  Of course
not.

Now that Peter has identified the trick - the question
is NOT referring to the (vertical) wings in a 90 degree
slip - what part of the airplane [i]is [/i]making lift?  What
is it's AOA?  Is it stalled?  Hint:  what do the Cl and
Cd curves look like?

[JW Scud]

Is the indicated stall speed less in a slip and higher in a skid?

Thanks

[Strega]

My cats breath smells like cat food....  who really gives a rats ass if the stall speed goes up or down?  just deal with it?  no?


Colonel..  would you rather have an airspeed indicator, or soft TP?  I know my answer ;)