Slipping in turns for precision power off 180

kontiki

kontiki

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Kontiki
I'm working on my commercial, usually flying a PA-28-201.

Sometimes in the precision power off 180 approach, my flight instructor recommends just keeping speed a little higher than best glide and slipping in the turn to get it down.

A coworker that sits in the cube across from me, built and flys a Pitts, and seemed shocked we'd do something so dangerous.

I believe he said slipping with wings level is OK, but at low altitude in a bank, if one wing stalls and cuts loose it could get ugly fast.

I think we really need to take it up to altitude and try it, to know for sure, but to be honest I really don't relish the thought of being upside down and uncoordinated.

Anybody know where to find the safe answer?
 
well if you are faster than best glide speed you really don't need to worry about stalling.

turning slips are required maneuvers for an glider rating
 
kontiki said:
I'm working on my commercial, usually flying a PA-28-201.

Sometimes in the precision power off 180 approach, my flight instructor recommends just keeping speed a little higher than best glide and slipping in the turn to get it down.

A coworker that sits in the cube across from me, built and flys a Pitts, and seemed shocked we'd do something so dangerous.

I believe he said slipping with wings level is OK, but at low altitude in a bank, if one wing stalls and cuts loose it could get ugly fast.

I think we really need to take it up to altitude and try it, to know for sure, but to be honest I really don't relish the thought of being upside down and uncoordinated.

Anybody know where to find the safe answer?
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Contrary to what many pilot's fear, stalling in a slip doesn't drop the airplane into a spin immediately and for a lot of airplanes recovering from stalling in a slip is actually easier than from coordinated flight. Many airplanes won't stall in a slip, turning or not, the slip reduces the effectiveness of the elevator. But even if you do nibble at a stall that Piper is mostly going to roll itself level. And in any case stalling at low altitude isn't all that good an idea whether or not you are slipping at the time.

Stalling from a skidding turn OTOH...:yikes:
 
As long as you are keeping the nose down, no worries.
 
kontiki said:
I'm working on my commercial, usually flying a PA-28-201.

Sometimes in the precision power off 180 approach, my flight instructor recommends just keeping speed a little higher than best glide and slipping in the turn to get it down.

A coworker that sits in the cube across from me, built and flys a Pitts, and seemed shocked we'd do something so dangerous.

I believe he said slipping with wings level is OK, but at low altitude in a bank, if one wing stalls and cuts loose it could get ugly fast.

I think we really need to take it up to altitude and try it, to know for sure, but to be honest I really don't relish the thought of being upside down and uncoordinated.

Anybody know where to find the safe answer?
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Go with what your flight instructor told you. A slipping turn to lose excess altitude is not uncommon.

Bob Gardner
 
A PA28 stall is pretty gentle and give you plenty of advance warning. As long as the wing is mostly unloaded during the slipping turn, I would not worry much about it. The PA28 is very capable of slipping while turning as long as your airspeed isn't in danger territory.
 
somorris said:
As long as you are keeping the nose down, no worries.
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:yeahthat:

Very important, keep nose down, very important.

Of course what the other folks say about slips-n-stalls is true but if the nose is down then the AOA < critical AOA and there won't be a problem. Just watch it at the round-out.
 
When I do my power-off 180s in our PA-28R-201 I just time my base to final turn so I can come in with out slipping. I typically turn in towards the runway by 30-45* after pulling my power. From that point on I just judge how fast I'm sinking at 79kts.

I have done slipping turns and don't much care for them. I have done them to make my point, but to me that means you turned in to soon. It all depends on how you were taught. I was taught to make it as normal and stable as possible.
 
Adding excess speed in a slip to lose altitude doesn't gain you anything. When you come out of the slip back to a normal glide you will have all that excess speed(energy) to lose. While you are dissipating the energy your are floating down the runway.

Your airspeed indicator will become somewhat inaccurate in a slip so you must use the aircraft attitude and feel to determine how close to a stall you are.

If you are not comfortable slipping without adding airspeed, take it to altitude with a competent instructor and do it until you are comfortable.
 
dillardrg said:
Adding excess speed in a slip to lose altitude doesn't gain you anything. When you come out of the slip back to a normal glide you will have all that excess speed(energy) to lose. While you are dissipating the energy your are floating down the runway.

Your airspeed indicator will become somewhat inaccurate in a slip so you must use the aircraft attitude and feel to determine how close to a stall you are.

If you are not comfortable slipping without adding airspeed, take it to altitude with a competent instructor and do it until you are comfortable.
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:yeahthat:

I agree with him. When you come out of the slip your energy is to high to touchdown without forcing it to land. If you come in at 79Kts (P28R)/Vg, fly the pattern without slipping and flare like a short field you will make a nice but firm landing at your point.
 
somorris said:
As long as you are keeping the nose down, no worries.
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Beware of overdoing that. I've seen a number of folks get scared at the typically low airspeed reading in a slip (due to the flow distortion across the pitot tube) and just bury the nose. Then, when they kick it out, they're shocked to see 85 knots or something like that (in their 172) as they attempt to start the flare, and go ballooning off into the sunset. Know the proper pitch attitude for the desired approach speed, and just hold it regardless of what you see on the airspeed when slipped, and it will all work out just fine.

But to answer the OP's question, keeping a bit of extra energy through the maneuver and then shedding it with flaps/slip once you're sure you have the landing zone made is a great way to ensure success in this maneuver.
 
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As has been said, just make sure that it's a slipping turn and not a skidding turn. Your coworker is thinking about the consequences of getting too slow in a skidding turn. When you plan to slip while turning, always use outside rudder. Or "step on the sky".

A very wise CFI friend (Jesse) once taught me this lesson when he caught me doing it wrong. After doing my research, I was very thankful for the advice.
 
ARFlyer said:
:yeahthat:

When you come out of the slip your energy is to high to touchdown without forcing it to land. .
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Only if you have the nose too low.

By practicing at altitude you can find the ATTITUDE that will allow slipping without gaining more energy. When you find this ATTITUDE you can then slip and when you come out of the slip back to your glide ATTITUDE you will be right on speed.
 
dillardrg said:
Adding excess speed in a slip to lose altitude doesn't gain you anything.
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Drag = 1/2 * density* Csubd * Area * Velocity squared.

Putting the nose down when flying sideways converts altitude into drag like it's going out of style.

When you come out of the slip back to a normal glide you will have all that excess speed(energy) to lose. While you are dissipating the energy your are floating down the runway.
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A little bit of slip will get rid of the energy in short order.

[qupte]Your airspeed indicator will become somewhat inaccurate in a slip so you must use the aircraft attitude and feel to determine how close to a stall you are.[/qupte]

That I will agree with. In a Cessna 120 I could get the ASI to read zero in a slip to the left.

If you are not comfortable slipping without adding airspeed, take it to altitude with a competent instructor and do it until you are comfortable.
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Nothing wrong with practice.
 
I get the impression that a number of people rely on those flap things and rarely do a "pedal to the floor" slip. Correct?

(My current ride runs out of aileron before it runs out of rudder, but that seems to be not typical)
 
Maybe a silly question, but why does anyone need to slip an Arrow on a power off 180? Thing drops like a rock with the power out.


Sent from my iPad using Tapatalk HD
 
Fearless Tower said:
Maybe a silly question, but why does anyone need to slip an Arrow on a power off 180? Thing drops like a rock with the power out.
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It's a matter of balancing energy versus descent path.

Yes, with gear and flaps down, at low speed, PA28's (especially the older ones with the "Hershey bar" wings) can have a pretty significant descent rate. For that reason, you have to keep the pattern pretty tight on the power-off 180 approach. Problem is that if you get the pattern too tight, you can still end up high. OTOH, if you were to loosen the pattern, you could find yourself without sufficient energy to reach the landing zone.

In order to keep an ace in the hole, the technique which appears to me to be most successful is to carry a bit of extra energy, and then dump the excess once you're certain of making the landing zone. At that point, you could drop the nose to reduce AoA and increase descent rate, or pull the nose up to increase drag further on the back side of the power curve, but both of those have serious down-sides. OTOH, a slip will kill that excess energy without increasing airspeed and drop you into the landing zone while allowing you to quickly reduce drag again and stablize the descent as you approach the flare point.
 
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Capt. Geoffrey Thorpe said:
I get the impression that a number of people rely on those flap things and rarely do a "pedal to the floor" slip. Correct?
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For me, it kind of depends on the airplane. I use both flaps and slips in the 170 but it has really small flaps.

Similar with flying a Warrior. Flaps are more effective, but not quite the drag of a 172.

I haven't found a need to forward slip 172s much.



Sent from my iPad using Tapatalk HD
 
kontiki said:
A coworker that sits in the cube across from me, built and flys a Pitts, and seemed shocked we'd do something so dangerous.
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A Pitts pilot thinks a power off slipping 180 is dangerous? He needs his Pitts card revoked! :D I took some video of how I do it in mine every time. Haven't died yet:

http://vimeo.com/34737384
 
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Ron Levy said:
In order to keep an ace in the hole, the technique which appears to me to be most successful is to carry a bit of extra energy, and then dump the excess once you're certain of making the landing zone.
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I agree with what you are saying....guess I have just found that adding flaps alone has been enough of an 'ace in the hole' to make the intended touch down spot in that particular airplane.
 
bobmrg said:
Go with what your flight instructor told you. A slipping turn to lose excess altitude is not uncommon.

Bob Gardner
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Thanks Bob. Some of the previous posts had me worried.

I got into a situation a few months ago where I had to do a tight base into a controlled airport and was not only making a tight turn but was high, so I simply made the turn into a slipping turn. It seemed natural enough and I put it on the numbers. I was proud of myself at the time, but started thinking I had done something dangerous when starting to read through this thread.

I NEVER slip without the nose down. On my checkride, the old curmudgeon DPE YELLED, and I mean SCREAMED, "KEEP THAT NOSE DOWN WHILE YOU ARE IN A SLIP!" I don't think he's supposed to yell, but as a result I don't think I'll ever slip without the nose down again although it was down as far as the instructor had taught me.
 
MBDiagMan said:
I NEVER slip without the nose down. On my checkride, the old curmudgeon DPE YELLED, and I mean SCREAMED, "KEEP THAT NOSE DOWN WHILE YOU ARE IN A SLIP!" I don't think he's supposed to yell, but as a result I don't think I'll ever slip without the nose down again although it was down as far as the instructor had taught me.
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First time I did a slip my CFI scared the crap outta me..."NOSE DOWN!!!"
...I never forgot again;)
 
MBDiagMan said:
I NEVER slip without the nose down. On my checkride, the old curmudgeon DPE YELLED, and I mean SCREAMED, "KEEP THAT NOSE DOWN WHILE YOU ARE IN A SLIP!" I don't think he's supposed to yell, but as a result I don't think I'll ever slip without the nose down again although it was down as far as the instructor had taught me.
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Doc, have you ever gone to altitude and tried to stall your airplane while slipping like you would do in an approach to lose altitude? In most airplanes, you don't need to be any more concerned the your nose attitude (airspeed) during a slip than during a straight-in coordinated approach. Curious how your Cessna behaves. The planes I've tried this in (Champ, Cub, RV, Pitts) won't really even stall in a full slip, much less show any tendency to spin...the fear of which is the reason many folks get nervous during slips and tack on unnecessary airspeed, which defeats the purpose of the slip. YMMV in different airplanes. Not saying you're likely doing that, but many do. Now if you did a skidded approach, I'd pucker like most folks seem to do during slips...before they gain enough experience to realize how benign they generally are.
 
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I did power off 180 in Arrow for my CPL. In this video called aim markers as touch down point.( I later change to second centerline as got more comfortable)
http://www.youtube.com/watch?v=-X9npT35MtU&feature=player_detailpage#t=286s

Arrow was one of the easiest to make power off 180 in my opinion

For my CFI; however, I had to do power off 180 in Mooney M20J. That was a pretty painful experience at gliding speed around 100 mph. I had to come higher and slip her at near level pitch attitude just to keep airspeed at the bay. Otherwise, Mooney picks it up airspeed in the matter of seconds

So in my opinion slipping is pretty safe (unlike skidding)
 
Capt. Geoffrey Thorpe said:
It would be pretty hard to maintain a yaw in the other direction.
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Depends how much power you have on the other engine. :wink2: Point is, it doesn't matter what you call it as long as you do whatever it takes to put the airplane where you want it and don't stall doing it.

Different planes have different techniques. The Grummans do well on this task by using half flaps and modulating the flaps for glide path control since there is little change in lift coefficient but a lot of drag change with flap changes. That lets you modulate L/D very nicely without changing speed, much like gliders and S-3's. OTOH, it is not a good technique in Cessnas due to the dramatic changes in lift coefficient (and thus stall speed) with flap changes. On Pipers, you can just about use the J-bar like a collective in a helo in this situation, making small, continuous flap position changes, withal it with more lift coefficient change than the Grummans but less than the Cessnas.
 
Ron Levy said:
It's a matter of balancing energy versus descent path.

Yes, with gear and flaps down, at low speed, PA28's (especially the older ones with the "Hershey bar" wings) can have a pretty significant descent rate. For that reason, you have to keep the pattern pretty tight on the power-off 180 approach. Problem is that if you get the pattern too tight, you can still end up high. OTOH, if you were to loosen the pattern, you could find yourself without sufficient energy to reach the landing zone.

In order to keep an ace in the hole, the technique which appears to me to be most successful is to carry a bit of extra energy, and then dump the excess once you're certain of making the landing zone. At that point, you could drop the nose to reduce AoA and increase descent rate, or pull the nose up to increase drag further on the back side of the power curve, but both of those have serious down-sides. OTOH, a slip will kill that excess energy without increasing airspeed and drop you into the landing zone while allowing you to quickly reduce drag again and stablize the descent as you approach the flare point.
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I do it by selecting a pattern that I think will work out slightly high with two notches of flaps, I can then dump more if needed.

I also had the engine pulled on me once much further away from the airport during my arrow check out. Took it to the flare with the gear up then went around. CFI hadn't expected me to make the runway and was wanting me to set up for a nearby field. She was however happy with my choice:wink2: I know the Com PTS wants a good wheels down landing but real world a belly landing is another viable option if the prop stops IMO.
 
Apache123 said:
Just wow.
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Seriously, once you get comfortable exploiting the airplane's capabilities, it really does feel like cheating...given how easy it is to put it down where you want without the need for power. It slips so effectively that you can put it where you want from a wide range of angles above your touchdown point, power off. It's not much of a glider, but I feel the incredible slipping capability really gives you the option of stuffing it into an emergency landing spot that would be difficult in many other planes. The slip in the video was not even full deflection. Power off full slip comes down 3,200 fpm. I really love that about the airplane. Plus it's a lot of fun. :)
 
whifferdill said:
Seriously, once you get comfortable exploiting the airplane's capabilities, it really does feel like cheating...given how easy it is to put it down where you want without the need for power. It slips so effectively that you can put it where you want from a wide range of angles above your touchdown point, power off. It's not much of a glider, but I feel the incredible slipping capability really gives you the option of stuffing it into an emergency landing spot that would be difficult in many other planes. The slip in the video was not even full deflection. Power off full slip comes down 3,200 fpm. I really love that about the airplane. Plus it's a lot of fun. :)
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Lots of ways to make the plane loose lift, much harder to add it back.
 
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