Stalling Video

[dutchroll]

Thought I'd put this up on the off chance anyone was interested. This shows an extended stalling sequence I did 2 days ago for the benefit of demonstrating controllability and recovery (particularly related to the Model 12 but it could equally apply to many aircraft).

 

Yeah my lips are moving - I had intended to provide a running commentary counting off speeds, altitudes, inputs etc, but my brand new intercom-iphone connector failed to record anything but a blank audio file. Some troubleshooting is required!

 

Stall is conventional with buffet onset immediately before, then a small pitch down. Full backstick was held until recovery some time later. A couple of small banks were made with aileron while fully stalled (note, aileron is not effective in all aircraft during a stall, and may be quite counter-productive in some! It was just for demonstration - do not oppose wing drop with ailerons in a standard stall recovery!). Applying opposite aileron to roll out did result in a wing drop (the precursor to an incipient spin) but this was easily controllable with opposite rudder, which you can clearly see.

 

Big engine, big prop = very rapid recovery upon applying power and releasing the backstick.

 

Stalling with bank on (e.g., a "base turn" config) yields much the same results. No big surprises in this aircraft.

 

 

 

[Guest asmol]

I would have expected a big difference in the angle of attack between stall and normal flight but it looks almost the same in flight.

 

In fact your stall just looks like a power off descent, why is this ?

 

 

[Ultralights]

16° AOA = stalled 15°AOA= Unstalled..

 

so only a 1 degree pitch change is required to unstall the wing. with a bit of practice, and good instructor, you can get stall recovery done in about 10 to 20ft height loss max.

 

 

[Guest asmol]

But there doesnt seem to be even 10 degrees between normal flight and the stalling ? unless its one of those GoPro distortion things.

 

 

[Happyflyer]

But there doesnt seem to be even 10 degrees between normal flight and the stalling ? unless its one of those GoPro distortion things.

It's the angle between the wing chord and the relative airflow. Because the aircraft is descending quite rapidly the relative airflow is coming from below, just imagine a line about 16 degrees down from the wing chord line.

 

 

[SDQDI]

Remember though it is AOA to the wind not the horizon so in straight and level wind flow will be relatively horizontal but once power off and slowed down into the stall the airflow will be coming from a slight downward angle so calculating AOA off the visual horizon we have with the camera will be slightly off.

 

Happy beat me lol but yes what he said ;-)

 

 

[facthunter]

Yes, Pitch attitude you can see but the relative airflow you can't see. (Unless you have a tuft of wool in front of you in a glider). Any time you stall in a turn you will be requiring more lift to maintain height and that involves more drag so the speed decay will be more rapid. While we are talking AoA it is also an energy management situation. You are running out of kinetic energy, ( V squared) so unless you use the big donk quickly the energy will come from height loss. Nev

 

 

[dutchroll]

Yeah everyone is pretty much on the right track here.

 

The pitch attitude shown by the camera relative to the horizon is not necessarily indicative of the angle of attack. Also wing incidence is a factor, and the attitude required for level flight also varies according to a number of factors.

 

As a matter of interest, the upper and lower wings also interact in their production of lift by virtue of their proximity to each other. Curtis Pitts designed his biplane aerofoils so the upper wing stalls before the lower one and creates a pitch down moment before both wings can stall.

 

 

[facthunter]

That's the way it's meant to be but DeHavilland with the DH82 put automatic slats on the upper (forward ) wings Nev

 

 

[Guest Maj Millard]

Foward wing or 'dominant ' wing ( lower wing on a Beech Staggerwing) should always stall first to ensure nose drop. A couple of degrees extra angle of incidence will ensure this.

 

 

[Catsy]

For interests sake, I always show students this video, it details exactly which part of the wing stalls first. The slow motion part is very useful also.

 

 

It really shows the wing washout effect (how the wing is aerodynamically engineered to stall the wing root (closest to the fuselage) first then out towards the wing tip):

 

- How it reduces the angle of incidence on wing tip compared to wing root,

 

- How the wing tip reaches critical angle later,

 

- How the wing is engineered to ensure the wing root stalls first, thus providing control buffet and a more stable stall.