Statistically, when is a stall more likely to happen?

[Ada Elle]

If you bring the nose up with power, the airflow from the engine over the elevator will make the elevator effective and get the nose up higher. If you then take that power off the nose will drop every time. This does not mean you have necessarily stalled. It just means the airflow over the elevator can't hold the nose up any more. Just as a nose drop doesn't necessarily mean a stall, if you don't get the nose drop it doesn't necessarily mean you haven't stalled. You could be mushing down fully stalled but the design of the aircraft is such that the centre of pressure hasn't moved back far enough to over power the elevator and cause a nose drop. In the end, if you don't get the stick back too far you won't stall.

It wasn't a gradual drop, though, more of a break - and I could hold the nose up without power down to about 40 knots, then it dropped about 15 degrees. With the stick in the same position from level flight, power off, I couldn't get it to drop the nose at all.

 

This aircraft has a stabilator with an anti-servo trim tab (like a Cherokee). Next time I'm in a Warrior I'll have to see if it behaves like this as well. I remember the Warrior mushing in the stall, too.

 

 

[Guest SrPilot]

From Buddy Holley and the Big Bopper to now, how many take-offs have resulted in otherwise mechanically sound airplanes becoming scrap a couple of hundred yards off the end of a runway? Old Man Emu

Ouch, OME, you forgot Ritchie Valens. He was on board that Bonanza too, and he was a great singer with a bright future ahead of him as were all three of these guys.

 

Here's a link to one of Richie Valens' albums in case he or his voice doesn't come to mind.

 

https://www.youtube.com/watch?v=7piklxzPMpg

 

I don't believe The Day the Music Died crash was a takeoff-stall crash. The Civil Aeronautics Board (now NTSB) investigators concluded that the crash was caused by flight into instrument conditions while neither properly certified nor equipped to do so, and a deficient weather briefing. The conclusions are still debated.

 

A tribute song to the 3 sang by a singer who died in a car crash on the way to an airport.

 

 

Here's a link to the news account (CNN, 3/4/2015) of the NTSB's consideration of reopening the crash investigation.

 

http://www.cnn.com/2015/03/04/entertainment/buddy-holly-plane-crash-reexamined/

 

[in the U.S., the old Civil Aeronautics Board (CAB), which investigated airplane crashes, was replaced by the National Transportation Safety Board (NTSB)].

 

A link to the original accident report:

 

http://www.ntsb.gov/investigations/AccidentReports/Reports/CAB_2-3-1959.pdf

 

 

[facthunter]

Elle The elevator is more effective when "blown" by the propwash, as is the rudder. The pitch attitude isn't the direct cause of a stall, It's the AoA basically controlled by the elevators. To get lift you need a positive pitch attitude and airflow. If you are hanging on the prop with a high pitch attitude and you will have the stick back to do this, when you cut the power you will RAPIDLY wash off speed so the plane will quickly lose height due loss of lift from the wings which are most likely stalled fully. Docile stall planes achieve their characteristics mostly by having elevators with limited back stick effectiveness and a C of G range not too far to the rear. Nev

 

 

[Ada Elle]

Elle The elevator is more effective when "blown" by the propwash, as is the rudder. The pitch attitude isn't the direct cause of a stall, It's the AoA basically controlled by the elevators. To get lift you need a positive pitch attitude and airflow. If you are hanging on the prop with a high pitch attitude and you will have the stick back to do this, when you cut the power you will RAPIDLY wash off speed so the plane will quickly lose height due loss of lift from the wings which are most likely stalled fully. Docile stall planes achieve their characteristics mostly by having elevators with limited back stick effectiveness and a C of G range not too far to the rear.

Nev - thanks, but I know that. My question was, in the same plane/CoG/configuration, why the docility of the stall depended on the pitch attitude just before attempting to stall.

 

From S&L: hold the nose in S&L attitude, stick fully back, mush at about 40

 

From 10 degrees nose up: hold the nose there, stick fully back, sharp-ish nose drop (10 degrees up to about 5 degrees down) when the ASI reads below 40

 

 

[facthunter]

I thought I explained that with the more RAPID loss of speed and corresponding lift. The steeper you get the more rapid and extent of speed change. Draw your weight lift drag vectors. Nev

 

 

[Ada Elle]

I thought I explained that with the more RAPID loss of speed and corresponding lift. The steeper you get the more rapid and extent of speed change. Draw your weight lift drag vectors. Nev

My original question was about stall stick position.

 

To quote the excellent djpacro (whose book was next to the cash register at the moorabbin pilot shop - very tempting...) at http://www.ozaeros.net//stalling/stalling.htm

 

For any given centre-of-gravity position, there is a simple relationship between stick position and angle of attack.

and we know that planes don't stall at a speed, they stall at an AoA.

 

so why, for the same stick position (fully back) do I seem to get a different AoA at the same CoG? (as experienced by the stall behaviour - mush vs drop).

 

 

[facthunter]

Because your elevators (as a primary control), are more effective when power is on, and the closer to vertical you get in pitch, weight acting more from the rear plus drag slows the plane quickly. Stick position related to stall is only valid if you don't change other essential parts of the equation. It doesn't make the concept invalid. If you want a knock down drag out dissertation on this. It's been done before. I doubt anything I have said is in conflict in substance with what's written in the link you posted. Nev

 

 

[Ada Elle]

Because your elevators (as a primary control), are more effective when power is on, and the closer to vertical you get in pitch, weight acting more from the rear plus drag slows the plane quickly. Stick position related to stall is only valid if you don't change other essential parts of the equation. It doesn't make the concept invalid. If you want a knock down drag out dissertation on this. It's been done before. I doubt anything I have said is in conflict in substance with what's written in the link you posted. Nev

If we are going to agree that speed doesn't contribute to stall, then why does the drag there matter?

 

I don't want a dissertation. I want to understand.

 

 

[Head in the clouds]

If we are going to agree that speed doesn't contribute to stall, then why does the drag there matter?I don't want a dissertation. I want to understand.

My students were noticeably divided into those who considered flying to be an art and those who thought of it as a science.

 

The art oriented ones learned to fly quickly and well, and although it was part of the curriculum, they never really needed to understand the science.

 

The science oriented ones tended to be slower to learn each discipline. I think they held themselves up, forever worrying about the minutiae instead of grasping the overall concept. Interestingly, once they learnt the art, they began to understand the science.

 

I'm a mixture of both, but generally science oriented ...

 

 

[Kununurra]

When you least expect it