Effect of Bank Angle and Pitch changes on Stall Speed

[kaz3g]

hi Rankamateur

 

It's very kind of you but I'm very much an amateur too. And I'm nowhere near as sharp as I was 40 years ago...but a lot more cautious.

 

Wiser pilots than me say that every flight is a new learning experience. I just hope I never stop learning.

 

Kaz

 

 

[motzartmerv]

Sounds like a fun move kaz.

 

What I'm getting at is the reason it stalled had nothing to dk with bank angle , slip, flap, rate of turn. And everything to do with where the stick was. That position won't change (generally speaking) :)))

 

 

[facthunter]

. You stall the plane with the elevator. YOU!... Nev

 

 

[kaz3g]

Sounds like a fun move kaz.What I'm getting at is the reason it stalled had nothing to dk with bank angle , slip, flap, rate of turn. And everything to do with where the stick was. That position won't change (generally speaking) :)))

Yes Merv, of course...and I unstalled it by shoving the stick forward and squaring things up with the rudder (power would have made it float even further).

 

What I am getting at is that the stall speed increases with angle of bank in a turn and it's easy to forget that if you are already close to the stall speed for straight and level flight then you will be even closer when you crank on a fair bit of bank in a turn.

 

I don't have an angle of attack indicator so I fly on my attitude and monitor my airspeed indicator reading as I suspect most others here also do. I don't consciously watch where I have the stick and don't really know what the ASI was reading when the wing dropped either. But it wasn't a vicious drop...quite lady like, really.

 

I learned the importance of approaching at the right attitude many years ago when I took an Astir CS for a winch launch and quick circuit after washing the bugs off it. I was already well and truly on the way up when I realised the ASI wasn't working properly (water in the pitot). That got my senses going!

 

Kaz

 

 

[kaz3g]

Just an additional thought, Merv, and I'm grateful for your contributions...

 

The focus on the stall stick position, as opposed the attitude of the aircraft, has always been a niggling concern to me.

 

It's not just because it sort of presumes that your attention is inside the aircraft, rather that whether or not the aircraft will actually stall right then is conditional on so many other factors.

 

Its nearly 30 years since I looped an aircraft by myself (although I had an awesome ride in Ian Temby's Yak 52TW a while back). The old Decathlon BIK certainly didn't stall whenever I held the stick nearly all the way back because I was travelling at the entry speed of 122 knots when I did it. Power wasn't the limiting factor because even further back the old Blanik L17's such as GOY and GIG looped just as well if not better at 86 knots with no noise up front (I did love flying them for their lovely handling characteristics)

 

Yes, if you doodle along straight and level at constant power with the stick just rear of the stall stick position you will stop flying but I'd be looking out the window at the horizon rather than watching where the stick was.

 

Kaz

 

 

[facthunter]

Everyone should be able to do a safe circuit in a basic plane without the ASI working.. One day a wasp will show you why.

 

In a turn who is going to say Er...my bank angle is 45, so my stall speed now is perhaps eleventy knots? so I need blimey percent increase on my normal manoeuver speed for my current weight and so on. It will be all over before you work it out.

 

Do some balloon busting, streamer cutting and dog fighting in a STRONG plane and find out how to do the tightest turn possible . But do it flapless for safety. ( so you don't excede your max flap speed.)

 

Kaz, you don't look where the stick is and it's not the pressure as that drops off as the speed reduces. You can judge it in relation to your knee or anything. that works as a datum.Nev.

 

 

[motzartmerv]

I understand kaz. But I have concerns also.

 

The angle of attack has nothing to do with horizon. Or the attitude. It's that sort of thinking that leads to these issues.

 

The angle of bank in a decending turn does not increase the stall speed ( alone)

 

You don't need to watch where the stick is. You hav it in your hand and being aware of where it is is crucial.

 

The elevator stalls the aeroplane. Not the horizon, not the bank angle, not the speed, not the slip, not the attitude. The elevator alone..

 

Using the airspeed and attitude to keep you from the stall is a potentially deadly mind set.

 

As I am sure you are aware, the aeroplane can stall at any speed,and in any attitude.

 

 

[Aldo]

Merv

 

Agree with all of what you are saying, an easier way to explain may be that the stall has everything to do with the angle of relative airflow to the leading edge of the wing (a lot of people don't understand this concept).

 

In the situation that Kaz is talking about at some point in time after the turn the nose had to come up to bleed off the speed that had built up in the turn and this where the stall angle may have been approached (not during the unloaded turn) and if still turning when this happened then the angle of the relative airflow may have changed quite suddenly as would the g loading.

 

Its all about inertia, you may apply all of the control inputs to change direction but the body in motion wants to continue in the original direction it was travelling (the same reason you get a high speed stall).

 

Additional to this is the fact you are doing something you don't normally do and when you look out the front the picture is vastly different to what you are used to and control inputs start happening by instinct to get you back to where it looks like what you know, add to this is that the ground is close and looks to be sliding past due to wind and you have a recipe for disaster.

 

You are able to do an 80 deg banked unloaded turn and never stall the wing this is achieved (as you would be well aware) by rolling in to the desired bank angle and letting the nose go to where it wants to but at some point in time you are going to have to deal with inertia and the relative airflow.