Flaps for Landing

[Ed Cesnalis]

1 hour ago, FlyingMonkey said:

Honestly, at our approach speeds I never found overshooting to be a big issue.  If it happens I just go into a shallow left bank (if making left traffic) and bring things back to centerline.  If flying a very tight pattern you might land a bit past the numbers, but it's no biggie unless the runway is very short.

Where pilots get into trouble is with a 'panic' correction when too close to stall, or skidding around the turn to try to minimize the problem.  This is especially dangerous in an airplane with a fast and unforgiving wing.  That should be a go-around.

I have found in the CT that if you just use a normal coordinated bank up to 30° or so (you probably only need half that unless you overshot into the next county), it usually works out fine.  And go-around is always in you back pocket.

Good post, I agree with all points except limiting bank to 30.  If needed I use as steep a bank as necessary but when doing so I keep my nose low and my wings not heavily loaded. I rely on bank I guess because its going the other way and not skidding into trouble.  In the end my instincts are safer.

[Tom Baker]

I have a lot of time sitting in the right seat watching others do landings. A couple things that have a big impact on the pattern size are engine idle RPM, and coordination.

I prefer an idle RPM around 1750-1800, and I fly a fairly big power off pattern, not rushed at all.

As far as coordination I often found that if I did a pattern after the student had done a couple, using the same landmarks for making my turns as they did I would wind up way high. It is really easy to let the CT be uncoordinated when gliding power off, and it has a dramatic effect on gliding distance.

My experience with the CTLS is that the extra flaps do not change the rate of descent much, but they do allow for a slower speed and steeper approach path. The slower speed on touch down means you need to absorb less energy to get the airplane stopped. This is desirable for short runways.

[FlyingMonkey]

1 hour ago, Ed Cesnalis said:

Good post, I agree with all points except limiting bank to 30.  If needed I use as steep a bank as necessary but when doing so I keep my nose low and my wings not heavily loaded. I rely on bank I guess because its going the other way and not skidding into trouble.  In the end my instincts are safer.

There is no aerodynamic reason to limit bank if your speed is high enough, other than all the normal cautions about aggressive maneuvering close to the ground.  Many instructors teach limiting bank angle to 30° in the pattern, so I'm echoing that as a general guideline for pilots of all skill levels.

[FlyingMonkey]

1 hour ago, Tom Baker said:

My experience with the CTLS is that the extra flaps do not change the rate of descent much, but they do allow for a slower speed and steeper approach path. The slower speed on touch down means you need to absorb less energy to get the airplane stopped. This is desirable for short runways.

I think I agree with this.  Rate of descent with 30° flaps is not hugely different from 15°.  However, the gliding *distance* is greatly reduced.  For that reason I have taken to only going to 30-40° flap settings when I am on final with the runway made.

I will always try to err on the side of being high instead of low.  I can always slip to lose altitude, even with a dead engine, but I can't gain altitude if the engine quits. 

[Ed Cesnalis]

33 minutes ago, FlyingMonkey said:

There is no aerodynamic reason to limit bank if your speed is high enough, other than all the normal cautions about aggressive maneuvering close to the ground.  Many instructors teach limiting bank angle to 30° in the pattern, so I'm echoing that as a general guideline for pilots of all skill levels.

Limiting the 30° bank to only when 'speed is high enough' defeats the purpose because the higher speed requires a bigger turn.

The 30° limit serves no purpose without wing loading.  A CTSW is short winged, short coupled, with very light wing loading even when compared to a 172 which has very light loading itself.  I don't fly my CTSW like heavier planes with comparatively heavy wing loading.  Steeply banked but lightly loaded turns in my CTSW is the easy way out of most things because the radius can be so tight that only a minimum of altitude is lost.  This descending turn is a better option for exits than a wing over or a level minimum speed turn 95% of the time.

What I'm trying to say is that its not just a skill level thing but also an airplane thing and the line, say your 30° line moves a bit.  When you have a 28' wing span, a 39kt stall speed, 11lb wing loading and short coupling you have some advantages that you can use (maneuverability) and sometimes more time for corrections (recovery).

[FlyingMonkey]

3 hours ago, Ed Cesnalis said:

Limiting the 30° bank to only when 'speed is high enough' defeats the purpose because the higher speed requires a bigger turn.

The 30° limit serves no purpose without wing loading.  A CTSW is short winged, short coupled, with very light wing loading even when compared to a 172 which has very light loading itself.  I don't fly my CTSW like heavier planes with comparatively heavy wing loading.  Steeply banked but lightly loaded turns in my CTSW is the easy way out of most things because the radius can be so tight that only a minimum of altitude is lost.  This descending turn is a better option for exits than a wing over or a level minimum speed turn 95% of the time.

What I'm trying to say is that its not just a skill level thing but also an airplane thing and the line, say your 30° line moves a bit.  When you have a 28' wing span, a 39kt stall speed, 11lb wing loading and short coupling you have some advantages that you can use (maneuverability) and sometimes more time for corrections (recovery).

Wing loading doesn't really have anything do do with my point.  In any airplane, with any wing loading, overbanking at slow speed will cause a turning stall.  If you are a little uncoordinated at the time and you have enough stick in it, you are now into a snap spin at low altitude (probably <400ft in a CT when making the base-to-final turn).

I stand by my statement that steep turns at less than 500ft AGL and at approach speeds can be dangerous.  Can experience tell you how close you can cut the margins?  Sure.  But as I said, the 30° rule is to protect new pilots from performing "stupid pilot tricks".  I will also state that if you need more than a 30° bank angle to get back on centerline in time to land, then go around for the love of God.

[WmInce]

6 minutes ago, FlyingMonkey said:

. . . "the 30° rule is to protect new pilots from performing "stupid pilot tricks".  I will also state that if you need more than a 30° bank angle to get back on centerline in time to land, then go around" . . . 

Concur totally.

[Ed Cesnalis]

13 minutes ago, FlyingMonkey said:

Wing loading doesn't really have anything do do with my point.  In any airplane, with any wing loading, overbanking at slow speed will cause a turning stall.  If you are a little uncoordinated at the time and you have enough stick in it, you are now into a snap spin at low altitude (probably <400ft in a CT when making the base-to-final turn).

I stand by my statement that steep turns at less than 500ft AGL and at approach speeds can be dangerous.  Can experience tell you how close you can cut the margins?  Sure.  But as I said, the 30° rule is to protect new pilots from performing "stupid pilot tricks".  I will also state that if you need more than a 30° bank angle to get back on centerline in time to land, then go around for the love of God.

30° can't by the right number for my Comanche, 201, and Bonanza and still be the right number for my CTSW.

Wingloading is quite relevant to your point, if you leave your wings loaded your point stands even if 30 is a conservative number.  My point is there is another route very accessible to a CT pilot.

I don't often overshoot and have successfully avoided it with steep banks.  95% of my canyon exits are done the same way.

[Warmi]

It has been always my understanding that  the stall speed increases in a banking turn only if you attempt to maintain altitude , in other words, load the wings.

If I need to do some rather steep turns at low speeds ,  I feel quite safe as long as I don’t load wings ( descending turn ) - it feels quite natural, safe and intuitive to me.

[Madhatter]

The greatest cause of ga fatalities is turn to final (FAA data). Low speed a lttle tail skid, nose drops which drops lower wing. When wing is lifted with aileron the angle of attack on that wing is increased due to down aileron and stalls first. No chance of recovery at 500 feet. There is a lot of data on this . The type aircraft is irrelevant . Watch that slip indicator. It happens in about 1 second. Lots of videos on this.

[Runtoeat]

A good cautionary point.  Can't be repeated enough.

[Ed Cesnalis]

This is reading like one side advocates obeying the 30* limit (for the love of god) and I am advocating something reckless.

This 30* limit mostly applies to typical trainers flown by students and the advice is given by their instructors (maybe its documented as well, I don't know).  The advice very much applies to new pilots and their upgraded Cirrus, Mooney, Bonanza, Comanche, ...

I'm pointing out that there is such a wide slow speed performance gulf between these aircraft and my CTSW that if 30* is a reasonable limit for a Comanche that really might bite the pilot quite easily here then its not the right number for my CTSW.

Our 39kt stall speed, short wings, short coupling and flaperons change the line where safe margin exists.  If a need for a 40* bank for instance to not overshoot final bothers you in your CT how are you possibly going to land in an environment full of shear?

I was check out in 2006 by and extremely good CFI (and whatever you call a guy that instructs in 747s).  He owned a CTSW and a Yak at the time.  The checkout took a short time with one correction.  I was told that I was not flying a skyhawk and my 30 degree banks in the pattern were less safe than 40+ degrees because I was needlessly blind in the turns for a much longer time than made sense.  I found this to be true immediately, that extra 10-15 degrees of bank in my CT created a condition that felt similar to my Skyhawk at 30 degrees.  

For me, in the pattern there is no reason for this 30 limit in my LSA but lots of reason for the much more rapid turn that allows me to see the traffic.

[Ed Cesnalis]

You stall your CT (even on base to final) with stabilator input not flaperon input.  The 30* limit is limiting the wrong control here.

(the 30 limit can actually cause the spin entry when the pilot high sides the stick to limit the bank.)

 

The way I stay safe without the 30 limit is by trimming my stab for 55kts where I have a nice centered stick and great protection from stall.  If I'm about to overshoot final, to remain safe all I have to do is a turn with zero back pressure. That works very well because so little altitude is lost that I can recover a new glide path on final.

 

[Tom Baker]

Ed, if you can't make the turn to final with 30° or less bank angle you have done something wrong. Plan your turn so you don't have to excede the limit. Plan to use only 20° and steepen to 30° if you need it. The increase in stall speed goes up by the same percentage regardless of the airplane your flying, and approach is flown normally at the same 30% above stall speed. The margins remain the same between aircraft. Also because of our lower speed we can fly the same ground track as those faster airplanes with less bank angle.

[Ed Cesnalis]

16 minutes ago, Tom Baker said:

Ed, if you can't make the turn to final with 30° or less bank angle you have done something wrong. Plan your turn so you don't have to excede the limit. Plan to use only 20° and steepen to 30° if you need it. The increase in stall speed goes up by the same percentage regardless of the airplane your flying, and approach is flown normally at the same 30% above stall speed. The margins remain the same between aircraft. Also because of our lower speed we can fly the same ground track as those faster airplanes with less bank angle.

Tom, I never said I can't, not doing anything wrong.  I don't want to use 20-30*, why take away my maneuverability and keep me blinded by my wing?  Less bank angle in a CT is the wrong objective.

Its just plain wrong to say a CT needs the same margin (in bank angle) as a Cirrus. Insisting to treat my CTSW the same as these heavier airplanes causes pilots to employ meaningless margin and give up other safety advantages the CT has to offer.  Another point is that a more steeply banked CT gains a lot of visibility out of the sky light.  I do my turn with better visibility in 10 seconds where your asking for me to be blinded for 30 seconds with no real benefit.

The increase may go up by the same percentage but I might be going as much as 20kts slower!!!!!      Compared to a spin entry in even my old Skyhawk that can happen quite suddenly on this turn with the controls crossed in an effort to limit bank in my CTSW I have a ton of extra time.  I can deviate for an unloaded steep turn without a big correction, can't do that in the faster heavier planes.

[FlyingMonkey]

The 39kt stall speed of the CT does not "protect" you from a turning stall, it just happens at a slower speed.  Stall speed increases with bank angle, wing loading has nothing to do with it.  Wing loading comes into play in determining at what speed in level flight the wing will stall (in the case you cited, 39kt); once you start turning the effect of the turn is very predictable in what happens to stall speed.

At 30° bank angle, stall speed goes up 8%.  At 45°, it goes up 18%.  So your 39kt stall goes to 42kt at 30° and to 46kt at 45°.  If you are flying your approach at 45kt, and make a 45° level turn, you will stall the airplane.  Which is why I mentioned originally that if you are slow enough and make a turn, you could be in danger.  "But only an idiot makes a CT approach at 45kt" you say.  Fair enough, but here's how it happens:

1) Pilot changes to 40° flaps on base, speed drops to a reasonable 50kt, which is almost exactly 1.3 * Vso of 39kt.

2) Pilot makes turn to final, but the crosswind is more than expected and he overshoots.  Drat!  He's concerned with his alignment and doesn't notice speed down to 49kt.

3) Pilot takes aggressive corrective action, and does into a 45° turn to get back on centerline.  He's not on a particularly tight pattern, and is a hair low already and wants to preserve his altitude to be on the right glide slope.  So he makes an essentially level turn.  He also subconsciously feeds a bit more left rudder in to hurry the turn, creating a slight skid.

4) In the 45°, 1.4g turn, at idle power, induced drag causes speed to bleed off quickly.  The 49kt airspeed bleeds to 45kt in a couple of seconds.  The pilot is totally confused when his skidding turn snaps into a full-blown spin and hes's suddenly staring at the spinning Earth.  The last he checked his speed was 50kt and he had plenty of margin...  

Epliogue:  The exactly same sequence of events with the only change being a 30° bank agle, results in no stall and no spin, because the airplane is still 4kt above stall when the pilot rolls out of the turn. We all know we'd never let the above sequence happen, but so did half of the dead pilots that did.  

"The stall speed in a manoeuvre (V_SM) increases as the square root of the load factor (LF)."  That is regardless of the wing loading or aircraft weight.

https://www.caa.govt.nz/fig/advanced-manoeuvres/steep-turns/

 

 

[Tom Baker]

Ed, which side of the airplane do you fly from?

[Ed Cesnalis]

15 minutes ago, FlyingMonkey said:

The 39kt stall speed of the CT does not "protect" you from a turning stall, it just happens at a slower speed.  Stall speed increases with bank angle, wing loading has nothing to do with it.  Wing loading comes into play in determining at what speed in level flight the wing will stall (in the case you cited, 39kt); once you start turning the effect of the turn is very predictable in what happens to stall speed.

At 30° bank angle, stall speed goes up 8%.  At 45°, it goes up 18%.  So your 39kt stall goes to 42kt at 30° and to 46kt at 45°.  If you are flying your approach at 45kt, and make a 45° level turn, you will stall the airplane.  Which is why I mentioned originally that if you are slow enough and make a turn, you could be in danger.  "But only an idiot makes a CT approach at 45kt" you say.  Fair enough, but here's how it happens:

1) Pilot changes to 40° flaps on base, speed drops to a reasonable 50kt, which is almost exactly 1.3 * Vso of 39kt.

2) Pilot makes turn to final, but the crosswind is more than expected and he overshoots.  Drat!  He's concerned with his alignment and doesn't notice speed down to 49kt.

3) Pilot takes aggressive corrective action, and does into a 45° turn to get back on centerline.  He's not on a particularly tight pattern, and is a hair low already and wants to preserve his altitude to be on the right glide slope.  So he makes an essentially level turn.  He also subconsciously feeds a bit more left rudder in to hurry the turn, creating a slight skid.

4) In the 45°, 1.4g turn, at idle power, induced drag causes speed to bleed off quickly.  The 49kt airspeed bleeds to 45kt in a couple of seconds.  The pilot is totally confused when his skidding turn snaps into a full-blown spin and hes's suddenly staring at the spinning Earth.  The last he checked his speed was 50kt and he had plenty of margin...  

Epliogue:  The exactly same sequence of events with the only change being a 30° bank agle, results in no stall and no spin, because the airplane is still 4kt above stall when the pilot rolls out of the turn.  He all know we'd never let the above sequence happen, but so did half of the dead pilots that did.  

"The stall speed in a manoeuvre (V_SM) increases as the square root of the load factor (LF)."  That is regardless of the wing loading or aircraft weight.

https://www.caa.govt.nz/fig/advanced-manoeuvres/steep-turns/

 

 

Andy,

You are not hearing what I am saying, your post quoted above doesn't apply because everything you say above applies to a loaded wing.  I am increasing my bank without increasing my stall speed. You only get to 1.4g by pulling back on the stick, and pulling back on it a lot, I'm saying don't do that part.

You know I'm flying the canyons in the Sierra, true most of my flights.  I spend a lot of time in an 75° bank and I am turning but at no more than 1g because I am trading altitude for wing loading.

2 minutes ago, Tom Baker said:

Ed, which side of the airplane do you fly from?

Tom,

Mostly left, sometimes I can only get a shot from the rig

[Tom Baker]

Just now, Ed Cesnalis said:

Tom,

Mostly left, sometimes I can only get a shot from the rig

if you are flying a standard left traffic pattern for the left side of the airplane then you don't gain any extra visibility with a steeper turn, unless you have an excessive bank angle.

[FlyingMonkey]

If you only make descending turns, you can keep the stall speed from coming up, that's true.  You made it sound like there was something special about the CT because lower wing loading compared to a Cirrus or other heavy airplane, regarding making steeper turns in the pattern, and there isn't.  

[Ed Cesnalis]

A CTSW will roll to any bank angle without stalling, it is well capable of doing rolls.  How is this possible?

My CTSW will do a descending turn at 90° and 1G or less. How is this possible?

You have your formulas that says stall increases with bank and while that can be true in real life its not the bank but the aft stick that causing the stall.  Remove the aft stick  and change to a descending turn and that stall business goes away.

 

[Ed Cesnalis]

1 minute ago, Tom Baker said:

if you are flying a standard left traffic pattern for the left side of the airplane then you don't gain any extra visibility with a steeper turn, unless you have an excessive bank angle.

we have a right and left traffic field.  I don't limit bank really so maybe I have an excessive angle at times.

Turning a CT steeper than other planes that are heavier and / or have longer wings makes sense everywhere not just in the pattern, the extra visibility often works.

[FlyingMonkey]

Just now, Ed Cesnalis said:

A CTSW will roll to any bank angle without stalling, it is well capable of doing rolls.  How is this possible?

My CTSW will do a descending turn at 90° and 1G or less. How is this possible?

You have your formulas that says stall increases with bank and while that can be true in real life its not the bank but the aft stick that causing the stall.  Remove the aft stick  and change to a descending turn and that stall business goes away.

 

Again, the math is for level turns.  Of course you can unload the airplane at steeper bank and keep the g forces low. But try a 90° bank keeping the airplane at 1g on your base-to-final turn and let me know how much altitude you have left when you roll out.  And I hope you have the flaps up to prevent the overspeed...  

[FlyingMonkey]

3 minutes ago, Ed Cesnalis said:

Turning a CT steeper than other planes that are heavier and / or have longer wings makes sense everywhere not just in the pattern, the extra visibility often works.

Now you are back to confusing me.  What does the weight or length of the wing have to do with steepness of turn?  If a steep turn is a valid technique in a CT, then why not in say, a Cessna 210?  If you are keeping your loading down by being in a descending turn, what does weight or wing length matter?  It's either good technique or it's not.

Are you talking about roll rate or something?

[Ed Cesnalis]

Just now, FlyingMonkey said:

Again, the math is for level turns.  Of course you can unload the airplane at steeper bank and keep the g forces low. But try a 90° bank keeping the airplane at 1g on your base-to-final turn and let me know how much altitude you have left when you roll out.  And I hope you have the flaps up to prevent the overspeed...  

90° at 500' would be excessive silly.  All you really need is a centered (trim) stick and no back pressure.