US AOPA pilots test fly (im)possible turns (various a/c)

[Garfly]

 

 

 

[Yenn]

I wonder if the Bonanza would have done better with a much steeper turn. What I saw looked very shallow.

 

I used to reckon I needed more than 500' with my RV4, but I was using a much shorter runway and my climb speed was always higher than max climb speed.

[facthunter]

To get the same turn radius with a faster plane you need more bank angle. They probably didn't want to GO there as it is inherently more risky..The 3 second delay equals more distance (in the wrong direction) as well. They  didn't mention more headwind  but the main message is there. I think it was covered well enough. Only JUST making it shows that easily you may not have made it. Nev

[walrus]

Demonstrated and taught in a Eurofox to do this. Immediate action is to get the nose down and achieve best glide followed a turn at a rate mindful that stall speed increases in a turn. That is what is critical. You must turn just above the stall for the bank angle.

 

‘’Don’t try this without a qualified instructor.

[Garfly]

 

This is from an AOPA article in 2017:

 

"Every basic flying handbook, including the Pilot’s Handbook of Aeronautical Knowledge, includes a diagram that shows the exponential increase in stall speed associated with bank angle. But bank angle itself isn’t the culprit. As the notes—too often overlooked—for the diagram point out, the graph is predicated on a level turn, and it is load factor that drives the increase in stall speed.  //

 

It’s important to understand that increasing bank angle alone doesn’t lead to a rapid rise in stall speed ...

 ... if you unload the wing—even if you’re a bit sloppy with the rudder or inadvertently bank too steeply in the turn—you won’t stall. And if you don’t stall, you won’t spin."

 

https://www.aopa.org/news-and-media/all-news/2017/november/flight-training-magazine/the-right-formula

[walrus]

yes, it is the load factor that determines the stall, but load factor is proportional to rate of turn. No load factor increase, no turn. Simples.

 

The difference between Your best glide speed and your straight and level stall speed determines the best rate of turn you can make. The Eurofox magic number for this exercise is 70 knots. It’s stall is somewhere around 35 knots - so you can pull almost a sixty degree steep turn at 70 without stalling. 

 

‘Don’t try this without instruction!

Edited June 5, 2021 by walrus

[facthunter]

It's a pretty good article. The "having things out of shape" was well qualified as it needs to be. "Unloading" the wing is a fairly foreign concept to the average pilot but it IS the "essence" of the solution to the problem.. No ONE "thing" is the sliver bullet. Unloading a wing is not something that can be done for long., as you have to lose lift required to unstall and that means you are going earthwards at an increasing rate at that point.

     Force =s Mass  x Acceleration. applies here.  You don't have the force when the acceleration stops.  Read the article a few times and think about every bit. Nev

Edited June 6, 2021 by facthunter
expand

[Yenn]

They didn't mention that it is always better to turn towards any crosswind component. That will tighten up the turn, but you will need to start aligning with the runway earlier.

[facthunter]

Are you sure you don't have that Rs about?  The other way (with the wind) often results in an overshoot of the runway centre line and a tendency to rudder it to increase the rate of turn to correct.  Nev.

[Garfly]

 

Unloading in the turn is well covered in this seminar video from 16:28 for about 10 mins. The topic here is the Canyon Turn, the other emergency course-reversal manoeuvre, this time with power available but with minimum radius the big factor.

 

 

[Yenn]

Yes Facthunter I did get it Rsabout.

[kasper]

On 05/06/2021 at 10:18 PM, Garfly said:

 

This is from an AOPA article in 2017:

 

"Every basic flying handbook, including the Pilot’s Handbook of Aeronautical Knowledge, includes a diagram that shows the exponential increase in stall speed associated with bank angle. But bank angle itself isn’t the culprit. As the notes—too often overlooked—for the diagram point out, the graph is predicated on a level turn, and it is load factor that drives the increase in stall speed.  //

 

It’s important to understand that increasing bank angle alone doesn’t lead to a rapid rise in stall speed ...

 ... if you unload the wing—even if you’re a bit sloppy with the rudder or inadvertently bank too steeply in the turn—you won’t stall. And if you don’t stall, you won’t spin."

 

https://www.aopa.org/news-and-media/all-news/2017/november/flight-training-magazine/the-right-formula

Absolutely agree.

 

I used a T85 thruster to demo this many years ago - in the 'impossible turn' if you shove the stick forward till its zero G and put in full aileron and rudder it will turn without stall no matter what ... and with the high drag and low speed it was entirely safe to roll/rudder out in the opposite direction with nose down and then pull back with wings level as airspeed allows.

 

In a T85 you turn 180 degrees with minimal heading displacement and are flying the opposite direction at approach speed with under 200ft lost.

 

As it was an impossible turn I was strongly guided not to demo it again as it might give people undeserved confidence in the ability to do the turn ... you must unload the aircraft and if you in panic or without thought do not it will probably kill you ... 

 

For me in a T85 I would consider an impossible turn possible from 500ft.

In the HM290 flea its the same 500ft and the same for even the Raven 912 at MTOW.

In all aircraft I fly I practice the 'impossible turn' at height and have a known and practiced personal procedure for low level engine failure. 

 

I currently do not fly higher performance aircraft so have not gone out at height to work out my personal performance limits for the aircraft but the same principle applies - without G load you can turn without stall and its all about how you come out of that situation and get back into landing mode.

 

And for the record I have used the remove G  to turn at low level once in an actual engine failure situation and I and the aircraft are still here to tell the tale .

[facthunter]

I've been doing this "forever" but don't bring it up often lest people try it without really comprehending what is happening and that won't work well usually..  We. ALL know a stall is an angle of attack thing and not a speed, don't we???  BUT if asked what your plane's stall speed is you say 43 knots (or whatever) straight away . What is it when you are pulling out of a dive at 2.5 G?  Who knows and you only know the "G" if you have a "G" meter.. 

  Anyhow I don't DO 2.5 G dives so who cares.?   Well you can't guarantee that someday, somehow you might have to. Could be a rotor near a ridge . Wake turbulence. A dust devil without the dust .You could flick out of a turn. Good news though. it won't stall unless YOU  stall it by putting the angle of attack to the relative airflow above around 14 degrees with the ELEVATORS..

  Unless you drive a taildragger you don't often push the stick forward ..  so it's not the normal thing to be doing in most circumstances. Nev .