Stall behavior

[FlyingMonkey]

Hey all...

 

A couple of days ago I took one of my pilot friends up with me for his first ride in the CTSW. We's a pretty light guy, but the airplane probably had 28-30 gallons in, so I'd guess our weight around 1290-1300lb. I demonstrated a power off stall for him, zero flaps at 2600 MSL. The airplane was perfect in the stall, a light buffet, then full stall. I held the stick full to the rear and the nose just rocked a little in pitch, 800fpm descent rate. No yaw or tendency for one wing to drop.

 

However, the buffet occurred at 50 knots indicated, and the stall at 48-49. Speed in the full stall read 50 with the nose just rocking. This seems fast to me...shouldn't the full stall at gross and 0° flaps be closer to 45 knots? I know speed indications are off near stall, but don't they normally read low, and not high? This has me rethinking my 55 knot approach speed...

[Ed Cesnalis]

I keep finding myself at 49kts or less on approach when I am light, pitching down does little to help, that is at 975lbs gross.

 

Your scenario would call for 65kt approach when at gross and zero flaps. By the time I slow to 65 I am already at 15 and looking for 62kts to deploy 30. Do you approach at 55, at full gross, with no flaps?

[Tom Baker]

Remember that the listed stall speeds are calibrated and not indicated.

[Ed Cesnalis]

Remember that the listed stall speeds are calibrated and not indicated.

 

Calibrated doesn't do me much good. If I'm not sure I will do a stall at current weight and landing flaps to know what to expect, 1.3 then becomes my confirmed indicated minimum.

[FlyingMonkey]

I keep finding myself at 49kts or less on approach when I am light, pitching down does little to help, that is at 975lbs gross.

 

Your scenario would call for 65kt approach when at gross and zero flaps. By the time I slow to 65 I am already at 15 and looking for 62kts to deploy 30. Do you approach at 55, at full gross, with no flaps?

 

I approach typically at 55 knots, 15° (most common) or 30° flaps. Usually hit about 51-52 knots over the runway threshold.

[Ed Cesnalis]

I approach typically at 55 knots, 15° (most common) or 30° flaps. Usually hit about 51-52 knots over the runway threshold.

 

Then your basis of 50kt IAS stall at zero flaps doesn't apply to the conclusion that 55 might be too slow. How about adjusting for flaps and weight? Heavy you might try 55@30 and 60@15 and light 50@30 and 55@15.

 

Higher speeds yet for zero.

[Tom Baker]

Calibrated doesn't do me much good. If I'm not sure I will do a stall at current weight and landing flaps to know what to expect, 1.3 then becomes my confirmed indicated minimum.

 

Andy was comparing the number from the book to what he was seeing from the indicator. I was just pointing out that these are 2 different types of speeds.

[sandpiper]

For me, 55K on final, 15 flaps, and light = a lot of float. Whereas 55K, 15 flaps, and near gross still has a little float but not near as much.

[Ed Cesnalis]

Andy was comparing the number from the book to what he was seeing from the indicator. I was just pointing out that these are 2 different types of speeds.

 

Ah,

 

He was comparing, as well the stall at 50kts to his 55kt approach speed, that was my focus.

[FlyingMonkey]

Sorry if I was unclear. I meant it looked like my stall speeds are higher than book speeds, and am wondering if that means my 55kt speed for approach might be a little slow. I don't notice float at that speed as Joahn mentioned, but I'm usually power off.

[Ed Cesnalis]

Yes it indicates that you are too slow to approach in that configuration ( zero flaps ) unless 10% is your margin but you use flaps so compare your demonstrated stall speed with landing flaps and then add your margin.

 

If you stall at 45 IAS with approach/landing flaps and your margin is 30% then your minimum approach speed is 58.5 knots. Your zero flaps stall speed doesn't mean a lot unless you are going to approach and or land with zero flaps.

 

You might want to try the stalls again and confirm the 50kt number it sounds high, also do the same thing solo and see how different your stall speed is when you are light.

[Anticept]

Indicated and calibrated speeds can be a few knots off in extreme cases. Remember that instrument installation varies from a/c to a/c. Calibrated airspeed is what the aircraft "feels", and indicated airspeed is an approximation.

[FlyingMonkey]

I'll do some more testing. The airplane feels pretty good at a 55kt approach speed with 15° or more flaps, even when heavy. I might be worrying about nothing since at 15° the nose is low and the AoA is thus significantly lower than when intentionally stalling at a high AoA. I have not yet practiced 0 flap landings, when I do I plan to use 60kt as the approach speed.

[FlyingMonkey]

CTLSi, I understand what you are saying. The slower speed means you come into the round out and rotate almost immediately into the flare. With more speed you get a few seconds after you arrest your descent before the sink starts and you need to flare. The downside of more speed (besides more energy), is those extra few seconds means time floating down the runway, which makes it harder to land short in a short field, and a flatter glide for obstacle clearance on approach.

 

Either way can work well, it's just preference IMO. I am much closer to the "full stall landing" camp, but not as married to it as Eddie and CT. Good on you for trying it both ways to see what works for you.

[Roger Lee]

I agree with Andy, it's just preferences.

 

One type of landing isn't any better than the next from 55 to 60 on an approach. One even has more of a error margin. It's just different comfort zones and techniques that work for that individual.

[Doug G.]

Here you go, this should end the argument, or not.

http://www.pilotworkshop.com/tips/landing_airplane_safely.htm

 

[Ed Cesnalis]

Doug,

 

The best part " a perfect landing for most general aviation aircraft is one where the aircraft touches down smoothly on the center line at just above stall speed with the yoke nearly full aft. The pilot then holds the nose wheel off as long as possible and smoothly lands it as elevator effectiveness is lost."

[FastEddieB]

"a perfect landing for most general aviation aircraft is one where the aircraft touches down smoothly on the center line at just above stall speed with the yoke nearly full aft. The pilot then holds the nose wheel off as long as possible and smoothly lands it as elevator effectiveness is lost."

 

Be still, my heart!

 

[Roger Lee]

Hi Ed,

 

Too analytical and too ridged on the task and performance side.

 

A perfect landing is smooth (with any stick position and any speed that accomplishes your specific task under your specific situation) and you get to put the plane away and use it again another day for the life of the plane without any repairs or damage.

I have lots of perfect landings, have never dropped a CT and I rarely meet your definition.

 

Your perfect landing description isn't for all planes, all situations or for all pilots.

[Ed Cesnalis]

So you want to redefine perfect to mean mediocre?

[Roger Lee]

It has nothing to do with mediocre. Your definition doesn't fit all circumstances , planes or pilots.

We have been land our CT's for years and yet very few probably meet that definition 100% of the time. So you are basically saying we are all mediocre? I would say we are all pretty good because we have tens of thousands of hours and landings that seem to work and don't meet that definition.

 

Smooth is smooth regardless of that definition.

[FastEddieB]

...landings should have a goal of...not scaring newbies as passenges, and getting down without messing with outers unduly.

 

I do not tailor my landings to my passenger's expectations.

 

That said, my passengers are normally fairly impressed by how slow and soft and uneventful the landing was.

 

If you have watched my landing videos, please point out the scary part - I don't see it.

 

As to the second "goal", I cannot decipher "messing with outers unduly".

[Roger Lee]

Original post

 

Stall behavior

 

 

Landings are done. The beat down, mutilated, maimed and did I leave out dehydrated almost dead horse has left the building.

[Ed Cesnalis]

Smooth is smooth regardless of that definition.

 

Smooth is a very low bar

[Roger Lee]

Then we are talking about the Limbo and that takes expertise and finesse, so that means your low bar definition is off too.

 

Still not stalls.