Thanks for that. I used to do s similar thing on the Menéstral. Take it up to 3000ft and stall, recover from the stall by putting the nose down without adding power until you were no longer stalling, then pull back again until another stall and so on until I had descended to 1000ft when I would add power and climb back to 3000ft and do it again. It cured me of my “trepidation?” for stall exercises.
I didn’t know it had a name though?
See this is what I’m talking about. @gallois you can’t compare driving on the road and flying a plane. The physics at play are not the same.
You want to see a nose below horizon stall? Here, watch this king stall spin, recover, still be nose 60° down and stall spin again:
johnh wrote:
At #2, you’re still slow. If you pull a bit too hard, you will stall again. That’s a secondary stall. No idea what it’s called in French (décrochage secondaire seems obvious, but who knows).
I can add that it is an accelerated stall. You are too aggressively trying to pull out of the dive after the primary stall (particularly with a wing drop). I’m pretty sure that it is part of the PPL syllabus, but of course it may be called something else entirely in French.
I can add that it is an accelerated stall
Not necessarily – if you don’t let the airspeed recover a bit before pulling then you will still be at Vs. As I understand it, an accelerated stall refers to a stall at >Vs, for example because you are in a turn.
@gallois – a good exercise is what is sometimes called a “falling leaf” (and sometimes not) – stall and just hold the stall. In any well-adjusted plane, you can do this
until you run out of altitude or get bored, using the rudder pedals to keep the wings level. It’s a great exercise. The nose will bob up and down as the plane accelerates, partly unstalls, pitches up and stalls again, etc – hence the name.
The conditions to induce a secondary stall include the fact that the nose is well down after stall recovery, and the airplane accelerating downward. Pulling to arrest the dive requires a pull of more than 1G, so the stall speed is now faster. I have done spin testing when the instrumented G pull to recover the dive after the spin recovery was 2.5G, so the airspeed required to not secondary stall is about double the 1G stall speed in that configuration. Thus it is necessary to allow the plane to accelerate to the speed at which the G pull for dive recovery is possible without stalling, before making the pull, to prevent a secondary stall.
Airborne_Again wrote:
You need both power and pitch to climb. No amount of power will make the aircraft climb if you pitch down!
@Airborne_Again. Could you elaborate (preferably with equations)? I’m not saying it is in incorrect, just that it isn’t obvious to me. I can imagine a scenario with the airplane in a shallow pitch down attitude such that the vertical component of thrust is downwards, but that the lift generated by the flying surfaces is sufficient to still result in a climb.
This is obviously impossible if the airplane is pointing directly down. As you change the attitude of the airplane by pitching up, at some point you cross the point where a climb results, but why is that point the horizontal? Is there some easy way to see this? Or is it just that in practice, the point is close to the horizontal? If so, how close? Could you still end up in a climb with a pitch angle (relative to horizontal) of say -5 degrees?
I have only taken a single aerobatics lesson, but I do remember the instructor telling me to add power when recovering from a stall when the nose was still pointing downwards. (Don’t recall what pitch attitude though, but it was definitely shallow). This was different to what I had learnt in other aircraft. It might be that this was completely unrelated to the point above.
Oh come on @hazek do you really think that that video proves your point? Yet you think that driving on a road physics are that different. But just in case it was why I gave the analogy of a low pass down a runway.
IIRC and it is a long time since I was at school both the prop on and aircraft and the wheels on a car provide forward motion.
Even in a slip or a slide there is a certain amount of motion towards the point you are aiming. On an aircraft adding power does not translate all that energy into lift. Some of it goes into yaw, roll, and forward moments. So yes in that way you can use a car on a road as an analogy. Many of the moments are the same. The thing missing in the car is, for the most part, lift unless of course by not turning the wheel you shoot off the edge of a cliff. But then that wouldn’t really be lift would it?
But I’ll try another analogy. You are coming into land. At about the height of a double decker bus (as described in many text books) you start the flare (a pitch moment or raising the nose) you go from a 3° descent angle to about 1°. And then gradually we pull back more and more so that we touch down softly on the main wheels. Why do we do that? Now in a lighter aircraft for instance like a Robin or a DA 40 you might reduce power to idle or near idle before the flare and rely on inertia to take you through the flare and to touch down. In a slightly heavier aircraft like a PA28 you might want to hold a bit more power into the flare otherwise you might come down with a bump.
Either way of you.are a bit fast or carrying a bit too much power and force the aircraft to touch down you are likely to bounce.
How high you bounce and what you do about it is a decision you have to make as PIC which is why you look at things like length of runway, wind speed etc before flight and update as you go along. Do we agree so far?
During the bounce unless you take action you are not really in control.
To take back control you might want to add a little bit of power then reduce slowly and lower the aircraft gently back onto its main wheels. Only really works If you are not going to run off the end of runway or if you do there is no obstacles to stop you suddenly.
The other choice is a go round. So you bounce, whoops apply full power and the aircraft will usually climb on it’s own but at what speed?
Now this is where we appear to differ.
As mentioned you are no longer in control during the bounce and you may find the nose pointing to the sky or at the ground or you might be lucky and it’s aiming at the horizon. My automatic reaction decided on through practice of recovery from unusual attitudes, is to first begin to pitch the nose to level flight. That is my initial reaction. My second reaction is to add power slowly and to control both yaw that comes with adding power and possible roll, depending on the aircraft type and wind direction etc. This does not mean that I will wait until I have achieved nose on the horizon before starting to add the power., I am simply maintaining control until I am ready to “rotate” so to speak and pitch up to climb at Vy and do another circuit, better this time.
IMO not to adjust pitch before adding power could:- in the event of a nose down attitude adding power first risks flying the nose into the ground.: In the event of a nose up attitude from the bounce adding full power quickly, risks not only risking a lag (full power not arriving immediately) but also an attitude conducive to a stall as part of the lift component of the increased power will likely increase angle of attack.
On top of that you still have to deal with the yaw moment and the possible roll moment.
I’m sorry if this all doesn’t fit with your physics knowledge but you have not shown me anything yet to make me change the methods I have acquired over the last 40 years.
If this doesn’t fit your picture of how everyone should fly a go around you should remember that in my first post on this thread in answer to Bosmantico I wrote that I didn’t like to be so prescriptive.
So if it’s “pitch, power, drag” for me and “power, pitch, drag” for everyone else. That’s okay with me.
Nota I have deliberately not mentioned the drag part as aircraft configuration brings a lot of different effects.
hazek I have never attacked you personally even though you decided on a personal attack on me and my nature despite the fact I have never met you. I would ask you to stop that. It is unnecessary. We can disagree without personal attacks.
@gallois, I want to extend my deepest apologies if my words came across as a personal attack – this was never my intention.
While I strive to stick to facts upon reflection, I recognize how the tone of my messages and my choice of overly emotional language may have crossed a line. For any distress or discomfort this caused, I truly am sorry. Moving forward, I will be more mindful in selecting my words and how I present my arguments, ensuring they are respectful and do not inadvertently leave a negative impression.
🙂👍
