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-   -   Forward Slip landings (https://www.airlinepilotforums.com/technical/125256-forward-slip-landings.html)

Douglas89 11-07-2019 02:24 PM

Forward Slip landings
 
I have my PPL checkride tomorrow (pending weather). I feel I am about as prepared as I ever will be. My CFI says I am probably one of the most prepared PPL students he has had. Extremely nervous...

I think I will do pretty good on the oral, but I am worried about the practical. I am most worried about steep turns and the forward slip to landing.

My steep turns are not bad, but sometimes on my left steep turn I bump the altitude a bit on roll out. I can't always get the trim out quick enough to not climb as I roll out (I try to put forward pressure while I take the trim out but will struggle to keep it from climbing). I have been doing 1 swipe of trim and then just back pressure for the steep turns. Before I was doing 2 swipes of trim, which was more difficult to not bump altitude on rollout.

The forward slip landings are my biggest concern. My approach and the slip itself is good, but I get so much float down the runway. I end up probably 200'-300' past the 1000' markers. When I start the actual forward slip on final I pitch for 70 kts. There is a park with lots of trees before the runway we typically land on (17). The air is turbulent over the trees, so I really do not want to go less than 70, because there is a tendency for airspeed to bounce around when flying over the trees. I do not want it to drop too much.

The chief flight instructor said if you have excessive floating you either have too much airspeed or not looking down runway enough. By the time I round out I am doing about 65-68 kts. I verbally tell myself to pick up my eyes to look down runway when I roundout.

Any suggestions so I do not float as far?

DontLookDown 11-07-2019 02:53 PM

What type of plane are you flying?

DontLookDown 11-07-2019 02:57 PM

Nvm I just saw another post from you indicating C172.

Youíve already been given good advice.

Some C172s donít recommend slips with full flaps. Adding full flaps after taking out the slip is one way you could add drag and limit the float.

Considering your checkride is tomorrow, donít overthink anything. Stay relaxed and confident and youíll do fine

JamesNoBrakes 11-07-2019 05:31 PM

So if you are at 70kts in the slip creating all that drag, just imagine the energy state you come out to when you straighten out with no drag on the fuselage. Thatís kinda like coming in at 75kts from a crazy high approach. The two things you can do are slow down in the slip or adjust the approach path shorter and round out higher to bleed more airspeed quicker to increase sink.

EMAW 11-07-2019 06:35 PM

Maybe I’m out of the loop, but 70 knots while forward slipping to a landing seems counter productive. I haven’t been in a single or worked on any of those maneuvers in years though.

Douglas89 11-07-2019 07:29 PM

Quote:

Originally Posted by EMAW (Post 2920031)
Maybe Iím out of the loop, but 70 knots while forward slipping to a landing seems counter productive. I havenít been in a single or worked on any of those maneuvers in years though.

Yea, maybe I should come in slower. I fly a 172N. It is lighter than the R models and definitely floats a bit more when landing. The few times I have flown a 172R, after roundout they just sit down.

Normal approach speed on final is 65. Perhaps like James mentioned, perform the slip at a slower airspeed. Maybe 65 instead of 70. I know that even a 5 kt. difference in airspeed on landings makes a pretty big difference in the 172.

Blackhawk 11-08-2019 01:40 PM

Your approach speed should be 1.3 times the stall speed in the configuration you are using. Usually stall speeds in GA airplanes are published for maximum gross weight. Since your weight is most likely less than maximum gross if you use the published stall speed to figure your approach speed you will still be fast. There is a formula for determining the decrease in stall speed with a decrease in weight but I canít remember it off the top of my head. Itís the same principle as pushing the nose over in an upset to decrease your stall speed. At an ďextremeĒ example at the top of a loop an airplaneís airspeed will be well below the published stall speed yet as long as you push (decreasing the aircraftís weight), you will not stall and will have full aileron effectiveness (which is how you do a half Loop with a roll).
Hope this helps instead of confusing.

JamesNoBrakes 11-08-2019 10:21 PM

Important to remember that you IAS during a slip is not a direct representation of the relative wind, the static port is either seeing more or less pressure than normal due to being exposed on the side of the fuselage, depending on which way you are slipping. So 70kts isn't really 70kts. Also, slipping at x pitch attitude (high drag situation), if you come out of that slip and don't change pitch attitude, you're going to pick up a ton of speed real fast due the lower drag, so you usually pitch up some as you come out of the slip, which all means you have to take into account the actual approach path, which isn't quite as simple as aim where you want to go, you have to make compensations.

Douglas89 11-10-2019 06:49 PM

I appreciate all the input from everyone. I passed the checkride! Woohoo. Honestly, I'm not as relieved from the stress leading up to the checkride as I thought I would be... I guess just knowing the mountain I still have to climb (Instrument, Comm, CFI)

My steep turns were very good. Stayed on altitude, maintained 45 bank, hit wake turbulence on roll out. They were probably the best steep turns I have ever done actually.

Landings were okayyy... The winds were from the North (normally from the south). So I am not as familiar landing on Runway 35. The approach is pretty different as Runway 35 has a very large displaced threshold. I tried to lock in on the papi. My approaches were stabilized but not as good as what I have been doing. I feel there were things I did not do as well as I normally do so I was disappointed in myself for that, but regardless I have my private pilot certificate now and can start working on my instrument.

TiredSoul 11-10-2019 08:13 PM

Congrats on your first milestone.
Stay humble, stay smart and enjoy the journey ahead of you.


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