Stalls, and turning.

[Tomo]

It's time we revisited this topic I believe... the latest accident of the Spitfire just reinforces the matter that even experienced pilots can get caught out and end up in a bad way.

 

I'm no instructor and it's been a while since I studied this, but from memory an aeroplanes stall speed at around 45˚ angle of bank at level flight (not climbing, or descending) is about 1.5G with a wing loading of 1.2 times stall. What that means is if you stall at 40kts wings level, you now stall at 48kts.

 

At 60˚ bank, level flight; it jumps up to a 2G turn, and 1.4 times the stall, so that would be 56kts for our 40kt stalling aeroplane.

 

This is in ideal conditions... smooth air etc...

 

So give yourself a mental challenge if you don't already know it, and think about what your aircraft speed needs to be for a certain bank angle. Don't forget to factor in climbing or descending into your thoughts.

 

Stall stick position is always a good indication also.

 

Just my few thoughts for the night, fly safe everyone

 

 

[Ultralights]

stall speed is irrelevant when it comes to stalling, AOA is.

 

 

[Billzilla]

stall speed is irrelevant when it comes to stalling, AOA is.

If you want to be really fussy, the AoA can also vary a little; the higher the speed the lower the stalling AoA is, but it's not a big enough effect to worry about.

 

To give an example of why AoA is more important than airspeed, back in the 80's when I was instructing I'd show the students a low-G arc, and at the top of the arc as the nose was level with the horizon the airspeed in the Piper Tomahawk would be down to only 40 kts with no stall warning horn blaring away. They stall S&L at 48 kts clean.

 

 

[djpacro]

Some info that I received from an overseas body which I forwarded to some-one for a coroner quite some time ago:

 

We have found the xxxxx to have very variable stall characteristics from one example to another, which we think is due to the fact that the leading edges and wing tips are rather hand-crafted and prone to variation, plus of course the basic shape. Some exhibit a sharp wing drop at the stall (more than 50 degrees) while other are fairly wings level. We require each one to be carefully evaluated and if necessesary, wing root stall strips used differentially (ie higher on one leading edge than the other) to even things out and minimise wing drop, plus give better pre-stall buffet warning. Some builders fit stall warners.The aeroplane is not difficult to fly and gives good speed cues, but like a Harvard, if you pull slightly too hard at the top of a loop it will flick off looking as though you meant to do an avalanche !

I have flown some Experimental Amateur-builts that I choose not to try again for health reasons. There was one in which I was unable to do a common garden loop - it was always an avalanche. Another had vastly different spin characteristics left and right.By comparison, a certified airplane would not be permitted more than a 15 deg uncontrollable roll at stall.

 

 

[Guest nunans]

I was going to ask a question some time ago but couldn't find a relavant thread to ask it in.

 

In relation to tommos numbers about angle of bank in a turn and incresed stall speed, is a wing level skidding turn a

 

real option (ie no increase in stall speed)? i bear in mind the recipe for spin = stalled + yawing so this would be one problem with my idea.

 

 

[bexrbetter]

When I drive down the street looking for a certain side street and suddenly see it, I don't slam on the brakes and desperately try to turn like some do putting myself at risk, I go past and casually find the next street or a clear area further up to turn back.

 

It seems to me some of these accidents happen, on face value anyway, through pilots struggling to get into position when they could just relax and go around again. Maybe the concentration of making the runway is draining the brain's resource of understanding what the plane is doing at that moment?

 

Forgive me if my analogy is way off, it's a casual observation and not directed at this particular incident.

 

 

[Admin]

(Couple of Off Topic posts removed)

 

 

[Guest Andys@coffs]

For those that want a specific text to read on stall vs roll John Brandons writing cover it at a level appropriate to rec flyers here. These turtorials can be accessed from this forums menu under resources, Tutorials

 

Andy

 

 

[facthunter]

The best way to do a turn is to use the lift forces from the wing and keep the balance ball centred. Slipping or skidding is a no-no. It's always an angle of attack that gets you into trouble. If you are in the top of a loop or barrell roll or bunting forward you can still be unstalled at very low speeds. If you unload the wing by forward stick you become unstalled virtually instantly, but you can easily stall it again as you can't get much lift at slow speeds. Nev

 

 

[Guest nunans]

So nev are you saying the increased drag from a wing level skidding turn may be worse than to just bank as required and add the backpressure?

 

 

[facthunter]

The wing would be the most efficient way of providing the force towards the centre of the turn, in all circumstances. Any other way is less efficient. Additionally steep turns not balanced are a control risk. You are set up to "flick" Nev

 

 

[boingk]

If you want to be really fussy, the AoA can also vary a little; the higher the speed the lower the stalling AoA is, but it's not a big enough effect to worry about.To give an example of why AoA is more important than airspeed, back in the 80's when I was instructing I'd show the students a low-G arc, and at the top of the arc as the nose was level with the horizon the airspeed in the Piper Tomahawk would be down to only 40 kts with no stall warning horn blaring away. They stall S&L at 48 kts clean.

Did the same in a C150 with my CFI - almost zero-G over the top of an arc and very low airspeed (less than 40kt) but still flying happily and no stall warning.

 

- boingk

 

 

[Tomo]

stall speed is irrelevant when it comes to stalling, AOA is.

As true as this is, I often wonder if it's the problem of why there is such a problem with people stalling their aeroplane 'accidentally', which often times ends in disaster!

 

Before you all decide to tie me in the stocks, I'm just trying to think practically now... but how many people stall their plane and crash doing negative G push overs?? Most times it's by someone, now lets face it, pulling back on the stick, increasing AoA - in return decreasing speed. The main component of LIFT is airspeed and AoA... however without airspeed, AoA is a bit useless.

 

You could get all philosophical but I just get a little frustrated when people say, 'airspeed hasn't really got everything to do with it' and use push overs and the like as descriptions... anything that makes it negative, you don't need lift!! If anything the lift is transferred to the top of the wing.

 

Any thoughts on that? I'm just wondering why people still 'don't get it' and stall and spin their plane into the ground! Stall stick position is probably more valuable than just saying AoA. (I know they're the same thing...but...)

 

 

[Ultralights]

pulling back on the stick until stall, the stick position will be same, weather it be at 40 kts straight and level, or at 100kts pulling out of a dive, its called stall stick position...as tomo said, learn it and remember it , could save your life one day.

 

 

[Bandit12]

As true as this is, I often wonder if it's the problem of why there is such a problem with people stalling their aeroplane 'accidentally', which often times ends in disaster!

I wonder sometimes whether some of the problems come from the lack of unusual attitudes recovery, as well as spin training. Not just your average stall training either, with the nose raised, power off and hold smoothly, but stalls in a descending turn, with the aircraft out of balance and a more sudden control movement (just like someone who quickly pulled a turn tighter to prevent an overshoot on finals).

 

I know that I didn't learn these from the standard PPL curriculum, and I also question the value of an EMR course 10 years later if you haven't been practicing in the interim. I don't think it is as much a problem that people can get into a bad situation - you can't train people to be able to avoid all possibly bad situations all of the time. But when it happens and you don't have the skills to recognise what is happening and how to get out of it, your odds aren't going to look good.

 

 

[Gentreau]

The turn onto final seems to be a common point at which these stall/spins occur.

 

They can be avoided if the pilot just holds the standard turn until the aircraft comes back to the extended runway line.

 

So I'm curious to hear opinions on this question.

 

Why does it sometimes seem that pilots have a obsession with "not overshooting the turn to final" ?

 

Is there something drilled into students ? If not why are people so bothered by it ?

 

Sure it's nice to be lined up perfectly from two miles out, but the only time when your exact alignment to the runway (in VMC) matters is as you cross the threshold.

 

.

 

 

[facthunter]

IF you've only done the close throttle and pull the stick back to hold the altitude stall thing you have little to prepare you for the inadvertant stall that usually happens in a turn when you've overshot the runway centreline on a base leg. People who assist the turn with a bit of rudder are flirting with death too. I think we teach stalling wrong. (Not everybody, just most). Really steep gliding turns are a good trainer . Have plenty of height and keep a lookout for traffic below..Nev

 

 

[boingk]

How about people just avoid the things altogether, have good airmanship... and heaven forfend... be *good pilots*?

 

Sweet, dear, zombie Jesus.

 

- boingk

 

 

[Bandit12]

I'm going to have to disagree with you boingk - you can avoid things all you like, take no unnecessary risks and demonstrate good airmanship, and still get caught out. Just because you are a "good pilot" doesn't mean you will do it right every time, won't ever get distracted or stressed, won't experience target fixation, won't lose situational awareness....... I'm no expert and no instructor, but I know how much better I felt from the day I started to learn about unusual attitudes.

 

 

[Guernsey]

The turn onto final seems to be a common point at which these stall/spins occur.They can be avoided if the pilot just holds the standard turn until the aircraft comes back to the extended runway line.

So I'm curious to hear opinions on this question.

 

Why does it sometimes seem that pilots have a obsession with "not overshooting the turn to final" ?

 

Is there something drilled into students ? If not why are people so bothered by it ?

 

Sure it's nice to be lined up perfectly from two miles out, but the only time when your exact alignment to the runway (in VMC) matters is as you cross the threshold.

 

.

What you say is true Gentreau however one GA training airfield in South Australia uses a left runway and a right runway operating on different radio frequencies so there is a risk of head-on collisions when two aircraft are on their base leg if they extend that leg.

 

Alan.

 

 

[boingk]

I'm going to have to disagree with you boingk - you can avoid things all you like, take no unnecessary risks and demonstrate good airmanship, and still get caught out. Just because you are a "good pilot" doesn't mean you will do it right every time, won't ever get distracted or stressed, won't experience target fixation, won't lose situational awareness....... I'm no expert and no instructor, but I know how much better I felt from the day I started to learn about unusual attitudes.

I agree with that, but a big part ofbeing a 'good pilot' is being aware of these things and how to minimise their effects, negate them, or avoid them to begin with. I wouldn't regard myself as anything special as a pilot - I've only got 80-something hours - but some people just seem to have the wrong attitude. Its not 'what happens' to you, its 'how did I get myself in this situation'. Once you realise how you can avoid bad situations or negate them when they do happen and are beyond your control, then you really start learning about being a 'good pilot'. At least, thats what I've been taught.

 

- boingk

 

 

[Jabiru7252]

What you say is true Gentreau however one GA training airfield in South Australia uses a left runway and a right runway operating on different radio frequencies so there is a risk of head-on collisions when two aircraft are on their base leg if they extend that leg.Alan.

Parafield operates on separate frequencies when the Tower is in control. When the airfield is CTAF then only certain runways are used and one frequency.

 

 

[Gentreau]

What you say is true Gentreau however one GA training airfield in South Australia uses a left runway and a right runway operating on different radio frequencies so there is a risk of head-on collisions when two aircraft are on their base leg if they extend that leg.Alan.

That sounds like a recipe for disaster, how on earth are they allowed to do that ?

 

 

[dazza 38]

What you say is true Gentreau however one GA training airfield in South Australia uses a left runway and a right runway operating on different radio frequencies so there is a risk of head-on collisions when two aircraft are on their base leg if they extend that leg.Alan.

Same as Archerfield when I flew there in the late nineties.When pilots trained and flew GA 5 0r 6 aircraft in each circuit. Probably won't have much of a problem these days.

 

 

[Ballpoint 246niner]

The turn onto final seems to be a common point at which these stall/spins occur.Why does it sometimes seem that pilots have a obsession with "not overshooting the turn to final" ?

 

Is there something drilled into students ? If not why are people so bothered by it ?

 

Sure it's nice to be lined up perfectly from two miles out, but the only time when your exact alignment to the runway (in VMC) matters is as you cross the threshold.

 

.

I see many pilots and students looking inside the turn, chasing the runway onto final- in doing so they fail to maintain a constant bank angle, tightening up the turn as you say, or skid it with rudder or lose the correct horizon reference attitude(airspeed) any one of these will contribute to bringing you closer to the stall; and clearly at a very dangerous point in the circuit!

 

Correct turning vigilence is one of my hobby horses, and "dirty" unco-ordinated turns show poor piloting. This may be a contributor IMHO.

 

The turn will finish when it finishes- forcing it can be fatal.