What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Slip with full flap

New member here. Returning to aviation after almost 20 years and am considering buying a used RV6/7.

Hypothetically ...

At 8000 feet my engine quits. All the normal restart procedures fail. I see a 2000 foot runway about 2 miles off.

So I head to my chosen approach area and begin a spiral, hoping to roll out on 1/2 mile final at 500 feet.

But, it turns into about 1000 feet agl and I'm just passing 85 mph - slowly bring on full flaps. Still gonna overshoot more than I want.

Can I aggressively slip with full flaps without fear of an exciting pitchover at low altitude?
 
Slipping with flaps........

One of the items on my RV-4 Flight Testing Cards was, at altitude, to apply full flaps at flap/landing speeds, slow to approach speeds and slip her with full flaps, left and right (which is done in the Cub nearly every landing, at least one direction.....:)). At the control deflection that you would likely do on a final approach (I don't remember doing full control deflection as "normal" had the desired effect), I didn't find any untoward problems...and she wanted to come DOWN........ Again, I am very used to slipping as I was raised on Cubs........

If you slow them up on final approach, they will want to come down just with full flaps. When I'm out practicing engine-out approaches, I find more often than not, I need to work the flaps including retracting them to keep her on the "glide slope". My left hand is on the (manual) flap handle using them as another control. And, as my instructor used to say (on final): If you want to come down, pull back on the stick. Want to come down faster: pull back more. Knowing where your stall speed is, of course.....

And pulling back power with a controllable pitch prop can be like a speed brake as well.....

Flight-testing your new ride will tell you a lot as well......

YMMV
 
I had the same question. Slips with full flaps work great on the RV-4. Looks like the space shuttle coming in.
 
I slip my 8 all the time with full flaps. BUT--at least on "my" plane, it starts shuttering at 71 KIAS. (About 81.6 if you're in MPH) So I don't get slower than the 71 Kts obviously.
 
The stricture against slipping with full slaps dates back to the Cessna 170, I believe -- and the very earliest models had a smaller vertical fin than the later ones.

It's my impression that the don't slip with full flaps advice once had merit but has since taken on a life of its own. That notwithstanding, the advice to try it at altitude is excellent advice.

I don't know, but I'd be cautious about spinning with full flaps. Potential for flap overspeed in the recovery, and potential for blanking the rudder. The Waco biplanes had trailing edge cutouts at the fuselage, and that was for spin recovery. I think...
 
The stricture against slipping with full slaps dates back to the Cessna 170, I believe -- and the very earliest models had a smaller vertical fin than the later ones.

It's my impression that the don't slip with full flaps advice once had merit but has since taken on a life of its own. That notwithstanding, the advice to try it at altitude is excellent advice.

I don't know, but I'd be cautious about spinning with full flaps. Potential for flap overspeed in the recovery, and potential for blanking the rudder. The Waco biplanes had trailing edge cutouts at the fuselage, and that was for spin recovery. I think...

Quite a few earlier 172's were placarded "Avoid slips with full flaps". Wasn't clear to me how they were supposed to land in a cross wind(!). They weren't "forbidden", just to "avoid". The issue was, apparently, that the downwash off the flaps could hit the horizontal stabilizer and cause some pulsation in the controls, which apparently un-nerved some pilots. I agree about flaps extended-I cannot imagine how one could recover from a full spin without exceeding the flaps-extended airspeed limits.
 
The stricture against slipping with full slaps dates back to the Cessna 170, I believe -- and the very earliest models had a smaller vertical fin than the later ones. ....

I used to have a 170. The restriction was because at the maximum flap speed, in a full slip, it would abruptly pitch down. At less than max flap speed, it was okay, at least at the weight and CG that I tested it.

The thing was, it was based upon test.

You need to determine the characteristics of your plane, yourself. Give yourself plenty of altitude.

Dave
 
I can attest.......

I also had a C-170. I'm pretty sure the slip w/flaps restriction was limited to the C-170B and the L-19. The combination of the "barn-door" flaps and the rather large rudder caused a situation where the flaps could blank out the tail. With the tail blanked out, the aircraft acted somewhat like a flying wing and the flaps became like elevators.

I tried it at altitude and confirmed that with full flaps and max slip, it DID tuck under. Rather exciting even when expected.

Later when the C-172 changed to a much smaller rudder (swept-tail), the rudder authority was much reduced and the problem went away.
 
Last edited:
I slip my 7 with full flaps all the time. Slow her down and she descends fast. Slipping increases the rate of descent even more. As has been said, know your stall...and don't. Used to slip my 4 with full flaps frequently as well.
 
Quite a few earlier 172's were placarded "Avoid slips with full flaps". Wasn't clear to me how they were supposed to land in a cross wind(!). They weren't "forbidden", just to "avoid". The issue was, apparently, that the downwash off the flaps could hit the horizontal stabilizer and cause some pulsation in the controls, which apparently un-nerved some pilots. I agree about flaps extended-I cannot imagine how one could recover from a full spin without exceeding the flaps-extended airspeed limits.

That was what I was taught also. I actually had a CFI demonstrate the "pulsation" once. A non-event.
 
I also had a C-170. I'm pretty sure the slip w/flaps restriction was limited to the C-170B and the L-19. The combination of the "barn-door" flaps and the rather large rudder caused a situation where the flaps could blank out the tail. With the tail blanked out, the aircraft acted somewhat like a flying wing and the flaps became like elevators.

I tried it at altitude and confirmed that with full flaps and max slip, it DID tuck under. Rather exciting even when expected.

Later when the C-172 changed to a much smaller rudder (swept-tail), the rudder authority was much reduced and the problem went away.

I am quite familiar with the suggestion to avoid slips with full flaps, however I have almost 1000 hours in L-19s, manual flaps as well as electric flaps, and I’ve tried the slips at all different airspeeds, attitudes and flap settings, I could never find the mysterious “tuck under”. Now the CH2T Alarus (piece of junk) bucks like a wild bronco with flaps in a slip, as does the Evektor light sport to a lesser of a degree.

As for the OP, get a comfortable RV pilot (doesn’t have to be an instructor per se) and play with slips at altitude.. also play with slowing down to “mush” it in (just be sure to build your speed for the flare), and also try S-turns on final. Hopefully you’ll never have the engine out that you are practicing for!
 
I was once a passenger in an Eastern Airlines A-300 Airbus. This plane was about the same size as a B-767. We were landing in Atlanta. I was pretty much in the back of the plane, when suddenly, I started feeling something very weird. I finally realized, the pilot was slipping the airplane. Don't know how kosher that is for an airliner, but if you're sitting in the back, it sure felt weird.:eek::eek:
 
I prefer no slips, lots of stress on the vert/rudder (I see lots of rudder skin cracks).
I've really misjudged things if I need to use full flaps and a slip.
 
Last edited:
New member here. Returning to aviation after almost 20 years and am considering buying a used RV6/7.

Hypothetically ...

At 8000 feet my engine quits. All the normal restart procedures fail. I see a 2000 foot runway about 2 miles off.

So I head to my chosen approach area and begin a spiral, hoping to roll out on 1/2 mile final at 500 feet.

But, it turns into about 1000 feet agl and I'm just passing 85 mph - slowly bring on full flaps. Still gonna overshoot more than I want.

Can I aggressively slip with full flaps without fear of an exciting pitchover at low altitude?

RV's slip well - just practice at altitude. The deck angle (and angle of descent near the ground in a full flaps descent) could be alarming to someone who hasn't experienced it. It will take a bit of nose down push on the stick.
 
I prefer no slips, lots of stress on the vert/rudder (I see lots of rudder skin cracks).

Where do they show up, Walt? Any speciffic problem areas?

(2000-hour RV-6 here, always interested in tips about cumulative degradation)

- mark
 
I recall an older thread on this topic. It is a long thread with good posts. Please search for that thread. Yes you can slip an RV or a Boeing 737 747 757.767 777 787 but you may make passengers uncomfortable.
 
I prefer no slips, lots of stress on the vert/rudder (I see lots of rudder skin cracks).
I've really misjudged things if I need to use full flaps and a slip.

From a power off maneuver at under 75 MPH??

I think Van himself would argue that point.

That's when you use the slip. So you should know how to do a slip in comfort.
 
Alternatively go around and try again. Not advocating one way or another, just different ways to skin the proverbial cat. Most pssengers hate skips because its a seemingly dramatic maneuver.

Edit: it's been pointed out to me that the premise of the tread is following an engine failure. My comment about going around...well, it's obvious why that's not possible post-engine failure.
 
Last edited:
Back
Top