Side Slips

[Warren]

Hi all

I have been told you can side slip a Ctls with flaps  extended, reading the Poh I can’t find it mentioned.

Just wondering if this is correct or not?
Thanks

Warren

[GrassStripFlyBoy]

I won’t specifically answer your question as I own a SW, but think about this in any airplane:  if you can’t side slip it with flaps, then it is not possible to land a crosswind with flaps.  That always goes against logic for airplanes that state no slipping with flaps extended.  I slip the heck out of my SW with flaps down.

[FlyingMonkey]

I agree with Darrell.  I probably use a slip to adjust my glide path on 60-70% of my landings, because I prefer to come in a little high and then scrub off the excess altitude on short final.

Some of the earlier Cessna singles are the only airplane I know of specifically that have cautions about using a slip with full flaps, because the flaps blank out the tail and there's a chance you might get into a condition where to lose tail authority.  This was later corrected, but since so many people trained on those Cessnas, it became a bit of aviation folklore not to slip with full flaps.  In most airplanes, CTs included, it's not a problem.

 

[Towner]

Don’t know that I’ve ever slipped with 40 degrees (cause I rarely use 40), but I do with 30 and 15 all the time.

Be careful with 30 because your airspeed wants to build if you aren’t paying attention and can bust your speed for the flap setting 

[Eddie Cesnalis]

I slip at 30 more than 40.  40 produces such a steep slope.  At 40 I'm more proned to point the nose down knowing speed bleeds off quickly and easily.  

Slipping at 40 works fine for me.

[Roger Lee]

You should be practicing at altitude and not on top of the runway because if you screw it up it's going to hurt. Leave a way out at altitude until you're sure you have your procedures down pat.

[coppercity]

Side slips (for crosswind correction) and forward slips (increased descent rate) can be performed with the CT at any flap setting.  There is a bit of tail blanking with full flaps using a full rudder forward slip. Not dangerous as it is subtle, but you might notice a slight pitch oscillation when it occurs and is easily remedied with a reduction in rudder and pitch down motion.  I have not noticed it at 30 deg or less flap settings.    

[Warren]

Thank you all for your comments. Very useful tool I intend to use.

[Anticept]

A sidebar: I find you can get a significantly faster descent rate without flaps greater than 0 as well. The flap speed limitations and consideration of the inaccuracy of the airspeed indicator mean that I have to slip at a really low drag speed.

Other aircraft have much higher flap limits and I don't have issues with those.

[FlyingMonkey]

On 9/14/2022 at 11:13 AM, Towner said:

Don’t know that I’ve ever slipped with 40 degrees (cause I rarely use 40), but I do with 30 and 15 all the time.

Be careful with 30 because your airspeed wants to build if you aren’t paying attention and can bust your speed for the flap setting 

Yes.  I have found at all flap settings that if you just push the rudder hard over and use opposite aileron, the airplane does indeed speed up.  I usually add back pressure to the stick at the same time I put a hard slip in, and adjust as necessary to keep my airspeed where I want it.  If you do it this way you 'll find you actually need a lot more back stick than you think, and it will feel a little unnatural at first because it feels like you are pulling your nose higher than you should.

FWIW, our flight school uses Diamond DA-20s, and they report the same behavior in a slip.  It might just be normal for slippery composite airframes.

I agree with Roger, practice at altitude.  Once you get it down you can slip all the way down to ground effect easily, if needed.

[FlyingMonkey]

18 hours ago, coppercity said:

Side slips (for crosswind correction) and forward slips (increased descent rate) can be performed with the CT at any flap setting.  There is a bit of tail blanking with full flaps using a full rudder forward slip. Not dangerous as it is subtle, but you might notice a slight pitch oscillation when it occurs and is easily remedied with a reduction in rudder and pitch down motion.  I have not noticed it at 30 deg or less flap settings.    

I have definitely noticed the pitch oscillation, even with 30°.  But I'm pretty aggressive with my slips and my approach speeds tend to be pretty slow compared to some, so that might be why I see it with less than full flaps.  I usually just let it do its thing, the oscillations cause little inconsistencies in the descent rate but otherwise no issues.

[Anticept]

One thing I suggest if you prefer to fly high in the approach is complete the slips and get back to your approach speed at least a quarter mile out. There shouldn't be obstacles by that point, and even if there were you should have enough energy to carry over them if need be.

[Tom Baker]

I don't think the picking up of speed in a slip has to do with a clean airplane, I think it has to do with fuselage side area. Aircraft that have a thin aft fuselage section seem more prone to pitch down in a slip, causing the speed to go up.

[FlyingMonkey]

2 hours ago, Tom Baker said:

I don't think the picking up of speed in a slip has to do with a clean airplane, I think it has to do with fuselage side area. Aircraft that have a thin aft fuselage section seem more prone to pitch down in a slip, causing the speed to go up.

Could very well be...I never took aerodynamics in school.  

[Anticept]

If you're picking up speed in a forward slip and you don't want to, raise the nose. Same rules apply to holding airspeeds as any decent, pitch for airspeed. Don't forget the ASI is inaccurate during a slip.

When you forward slip, you should not be picking up speed at all when done correctly, while greatly increasing drag and altitude loss, and while holding a selected airspeed of your choice accounting for inaccuracies.

During a slip, part of the stabilator will be blanked by the tail, reducing its effectiveness.