45 knots on base, hmmmm

[Ed Cesnalis]

I'm glad the summer air is over. Yesterday's flight was with a simple 10 knot west wind.

 

On my landing approach I used a closed throttle and 30° flap setting, trimmed for 55 knots and I came out of my turn to base at 45 knots. I saw the slowing right away and did the turn with forward stick pressure and exited with my nose down more than 25°.

 

My instincts say pitch down and my experience says power will fix as well but this time I decided to do neither and instead see if the airspeed will come back and it didn't. I finished the base leg near 30° nose down and brought in power for my turn to final. Speed normalized and final and landing were normal.

 

On reflection I am visualizing a lee side rotor right in the pattern down below 500' agl in the area that would be a tight base for a CT. The wind was smooth and so was the over the falls glide path.

 

I really expected to simply regain needed speed due to a steep pitch down attitude and I'm sure it would have prior to losing all of my altitude.

[Jim Meade]

I've read this twice and still don't understand it so I'll get back on my combine repairs and see what evolves.

[Ed Cesnalis]

Terrain on downwind is about 600' then drops rapidly. The pink shows my flight path and the blue the 10kt west wind. I have needed a lot of power here before and only now after thinking about it, the wind is following the terrain and sinking enough on base to need power and an extremely low pitch attitude.

 

[WmInce]

Just imagine a German dive bomber diving toward a target with 30 degree flaps, throttle at idle, making a turn at 45kts and the picture starts to form.

 

Not a credible analogy.

 

Besides that . . . those German pilots were quite good!

[Ed Cesnalis]

We have lots of rotors that cross the runway from the big glacial moraines when the wind is southerly. After looking again the big ridge crossing downwind but not the runway is a natural set up for a rotor that doesn't cross the runway but is right there for a very tight pattern.

 

When it is rotoring here it would be tough to do a dead stick from pattern altitude.

[FastEddieB]

What is the stall speed of your CT in the configuration where you saw 45k indicated?

 

It just does not sound like much of a margin if gusts or rotors are anywhere in the picture.

 

In any case, I would not have chosen to linger there and experiment with pitch and/or power or neither. If I understood your original post, that is. Like Jim I read it a couple of times to get the drift.

 

 

[Ed Cesnalis]

Stall is 39kts. Like most of my landings this was dead stick practice and with my nose down almost 30° I was expecting to see the speed recover.

 

With the nose down and my hand on the throttle and smooth air I was comfortable. Actually I did the prudent thing in that I could have made my final turn without power but decided to get in a better energy state and figure it out later.

 

I did learn something obvious that never occurred to me before, if you have to cross a big ridge close to the ground on downwind you might find meaningful sink on the other side especially if the wind is square to the ridge. Why would this be a lesson to me? I know this when I'm flying but my brain doesn't consider it because I'm in the pattern?

[Jim Meade]

Ah, you mean like at Sturgis, SD.

 

Good point. I used to teach at a short, narrow airport with lots of trees, buildings and other generators of mechanical turbulence. At first, the students were just trying to get keep the clean side up, but as they developed experience and skill one could teach them that they could look at wind direction and speed and make some very accurate estimates of when and where the gusts would affect them. They could then be ready to apply control inputs that were very well coupled with the gusts and thus "stay ahead of the airplane". It's a skill that once learned we all can apply.

 

It is impossible to over state the value of learning ground reference maneuvers and applying that knowledge to pattern work. Too many CFI's treat GRM as artifical exercises when they should be always taught with reference to pattern work. Wind direction and speed for ground track, banking according to wind direction and speed, learning to attitude fly with the eyes out side the cockpit and the ears open to variations in motor pitch and cabin wind noise.

 

Oh, was I on a rant? Sorry.

[Ed Cesnalis]

Mystery solved, I can now replicate. All I need is to fly solo with low fuel and no baggage, at that weight when I close the throttle and lower the nose to the normal attitude with 30flaps my speed goes right under 50kts, same thing with another 3-400 lbs and the resulting speed is around 55kts.

[Tom Baker]

I had a student say the other day, that without me in the airplane the pitch attitude on approach was really different from what he was used to seeing.

[Ed Cesnalis]

I had a student say the other day, that without me in the airplane the pitch attitude on approach was really different from what he was used to seeing.

 

I assume the student's target was a set approach speed and there was no adjustment for the lighter weight of flying solo.

 

I also assume that the closed throttle, 30 degrees, drooped wingtip level technique does adjust for the lower weight and I'm still at 1.4Vso but at a lower speed. If this is correct its an easy way to get your lower stall speed before landing when you are light.