Dangerous teaching

[nomadpete]

If turning back, do you turn into the wind (assuming there's a degree of crosswind)?

In GLIDING (please take this in the context of glider activities) -

Murphy's law dictates that there will seldom be an ideal wind blowing straight down a strip. So, PRIOR to take off, you check the wind sock and predetermine which way the cross wind component is. Then you say to yourself, "In the event of rope break at (X height) I will pull the cable release, lower the nose and turn downwind, then turn back". All in the one movement. That way, the downwind part of the turn (away from the strip) is made with the greatest glider speed added to the crosswind speed, and the last part of the U- turn is made after speed has bled off, allowing the cross wind to drift you back onto line with the runway. After that you still have to deal with a downwind landing. The goal is to avoid a 'S' turn onto final at low air speed and height.

 

Of course, this practice would only translate to noisy aeroplanes at a much greater height. Generally a glider is being towed with an airspeed that is gives a higher margin before stall speed, than can be expected with a powered aircraft set up for climb. Combine that with a much nicer sink rate, and the manoever becomes a practical emergency procedure for a glider whilst still being very risky for a powered aircraft.

 

The decision to turn a glider back MUST be made automatically and instantly, whilst airspeed is still high. That is why it must be rehearsed in the mind as part of each pre takeoff checklist. The height at which it is a safe option will depend on all variables such as obstacles, wind speed, lack of safe ground ahead, aircraft performance.

 

 

[Gforce]

[Guest Howard Hughes]

Impressive, but a power off turn (with no reaction time allowed for), is a lot different to an engine failure at 300 feet!

 

 

[facthunter]

He knows it is going to happen so the reaction time is not there. This shows that you have to enter the turn immediately to have any chance of getting there. There was really no height to spare, so had there been the slightest hesitation or less bank used it would not have worked. With two people it wouldn't have worked either. He was never high enough to require a sideslipping height loss which would have been the only safe situation. Nev

 

 

[Sapphire]

There is lots in the reaction time advantage. As you are climbing you can concentrate on your glide angle distance, phyche yourself up with confidence and pick a safe point to kill the power. Try the same while concentrating on the radio with your eyes glued to multiple conflicting traffic. The instant fright in some pilots would put them near stall requiring hundreds of feet to get best L/D speed, if that is even known. By then the turn back to the airfield hasn't even started and the opportunity lost.

 

 

[nomadpete]

There is lots in the reaction time advantage. As you are climbing you can concentrate on your glide angle distance, phyche yourself up with confidence and pick a safe point to kill the power. Try the same while concentrating on the radio with your eyes glued to multiple conflicting traffic. The instant fright in some pilots would put them near stall requiring hundreds of feet to get best L/D speed, if that is even known. By then the turn back to the airfield hasn't even started and the opportunity lost.

A real engine fail on takeoff is completely different from a rope break on a glider launch. With a glider, there is no grey area. Rope breaks - it is instantaneous and unambiguous. You are usually flying at 20kts or so above stall speed and can use that to execute the 180 without massive height loss. So the training kicks in instantly since there are no other decisions to delay things. However, when an engine falters it is seldom an instantaneous failure, and a first reaction (whilst the mouth is checking for the right expletives) is to scan the instruments and assess what is going on. Those seconds are all it takes for airspeed to bleed off even if you did put the nose down (draggy ultralight verses a slippery glider) and you cannot get it back without trading off a lot of height. Next reaction is to try to stretch the glide whilst turning low............ very risky. I'd rather opt for a controlled survivable crash rather than the likely stall and spin that would be next.

One other consideration is this: I had my Lightwing fan stop at about 300 feet. Now, if I had everything going for me and I managed to instantly execute a perfect 180, (in reality it would need closer to 500' height) I would have another big problem. I would be landing downwind with a set down point that left me with less than half of the strip to get on the ground and come to a stop before the fence stopped me. In the event I landed ahead and rolled to a stop just past the end of the strip. Lightwing glide ratio = 9:1, Training two seat Glider ratio = 30:1 That's three times further.

 

 

[Bandit12]

That video showed two things really well. First, just how far off the centreline the Fox had got. Second, this guy practised it, and still didn't do a great job on the second aproach. He touched down heavily with a lot of sink, sideways and on the edge of the strip. He needed to go to full power just to stop himself from wrapping it up in a ball.....

 

 

[Camel]

 

Just to state the obvious in case anyone missed it, the aircraft was well and truly airborne say 100 feet over the parked aircraft, on return he touched down at where the aircraft was parked so my point is if the strip length was shorter he may not have made it given he had everything in his favour include no weight i.e. passenger. Also in strong wind there is advantage to get back but the chance of stalling in turn much higher plus a much faster ground speed. ( referring to steep turns downwind if someone has a easy explanation for the inexperienced so they may understand the danger of the downwind turn in strong wind. Please do so. )

 

 

[Sapphire]

The way I understand it if you turn to downwind you create an immediate decrease in lift as your IAS will drop off. Then the plane is accelerated by trading off some height and you achive same IAS and same lift. Net result is less time in the air. Turning into wind is the opposite. Your IAS increases, and use that to stay in the air longer. However, turning into wind decreases your ground speed and turning downwind increases your ground speed. The one into wind will help you avoid a stall and allow a tighter turn. The wind gradient into wind will go against you compared to downwind. Work that all out in your one second reaction time.

 

 

[Gnarly Gnu]

Is this* being serious or is it a bit of a spoof?

 

* downwind turn stall

 

 

[Sapphire]

*serious and no spoof*-learn your basic principles of flight.

 

 

[turboplanner]

Don't know where you got that from Sapphire the aircraft is like the bee in the bus - it's flying in a slug of air, doesn't know the bus is doing 80 km/hr

 

The aircraft is pulling it's way through a moving patch of air so airspeed doesn't change - it's groundspeed which changes.

 

See this link, Motz's post #173 to see the unexpected hazard in a descending turn:

 

http://www.recreationalflying.com/threads/you-have-been-told-by-kevin-walters.40364/

 

 

[Sapphire]

Ever heard of inertia? We are talking about momentary effects which in very light a/c is small.

 

In doing a 180 deg turn power off, I would more consider a direction to turn that puts me in best position for a landing. Also, I would prefer a turn downwind initially at a higher altitude that allows a turn into wind onto final. Again, lot depends on direction of wind in relation to airfield and how high you are. A lot to consider in your 1 sec reaction thingo.

 

 

[turboplanner]

At ground speed, yes.

 

 

[Sapphire]

At ground speed, yes.

You will always have ground speed until the a/c stops????????????????

 

 

[Gforce]

Just to state the obvious in case anyone missed it, the aircraft was well and truly airborne say 100 feet over the parked aircraft, on return he touched down at where the aircraft was parked so my point is if the strip length was shorter he may not have made it given he had everything in his favour include no weight i.e. passenger. Also in strong wind there is advantage to get back but the chance of stalling in turn much higher plus a much faster ground speed. ( referring to steep turns downwind if someone has a easy explanation for the inexperienced so they may understand the danger of the downwind turn in strong wind. Please do so. )

I posted this video ( not mine ) to domonstrate that IMHO, the 180c turn back is rarely ever, a safe option and never the safest option. This was done with no passager, probebly in nil wind ( hench the pilots ability to take off and land in different directions and I would suspect, minimal fuel so in a very artificial environment. Try it with 2 up, full fuel and your weekend bags... It may not come out like that at all !

 

 

[Sapphire]

I've seen grossly overweight in critical situations and pushing up daisies.

 

 

[facthunter]

If you are going to do the turning down wind thing and ILLUSIONS and reality we had better start a new thread. I suspect it has been done thoroughly before, in which case maybe start back there. It is quite a hard thing to get your mind around and some won't be convinced at the end of it. Nev

 

 

[metalman]

*serious and no spoof*-learn your basic principles of flight.

I agree You should learn the basic principles of flight, once an aircraft leaves the ground it's indicated airspeed is unaffected by which direction the wind is coming from only ground speed differs , otherwise we would have to adjust our IAS depending on where the wind is blowing from, have you ever decreased your IAS by whatever tailwind component you have, or added your head wind to your IAS , that kind of thing would kill more pilots than turn backs do!

 

 

[facthunter]

There is a wind gradient effect that can bring you undone climbing in a tailwind situation. ie the freestream velocity is higher than the wind near the ground. same as in a flowing river where flow at the middle is faster than at the bank. Nev

 

 

[Sapphire]

I agree You should learn the basic principles of flight, once an aircraft leaves the ground it's indicated airspeed is unaffected by which direction the wind is coming from only ground speed differs , otherwise we would have to adjust our IAS depending on where the wind is blowing from, have you ever decreased your IAS by whatever tailwind component you have, or added your head wind to your IAS , that kind of thing would kill more pilots than turn backs do!

Metalman, I'll bet you a box of welding rods [ss] I am right under conditions I already explained. You turn into wind and once established straight and level your IAS is comfortably the same. However your ground speed changes, as you said, and becomes slower. So you are changing your speed relative to the ground when turning into a headwind [or tail wind as well]. If you tried to maintain your same ground speed then your IAS would change [by changing power] See the relationship? Lets look at it with numbers. You have a ground speed of 100 kts and you turn into wind and now you have a ground speed of 80 knots and so in relation to the ground you have slowed down. But he a/c has inertia [look it up]. It will not slow down instantly. That is where you IAS increases just for a few seconds. Not much and other errors affecting the accuracy of the asi may mask it [especially if the turn has a little slip in it] Gliding books discuss this effect in relation to entering thermals and changes in wind velocity. Your explanation doesn't relate to anything I wrote.

 

 

[metalman]

Metalman, I'll bet you a box of welding rods [ss] I am right under conditions I already explained. You turn into wind and once established straight and level your IAS is comfortably the same. However your ground speed changes, as you said, and becomes slower. So you are changing your speed relative to the ground when turning into a headwind [or tail wind as well]. If you tried to maintain your same ground speed then your IAS would change [by changing power] See the relationship? Lets look at it with numbers. You have a ground speed of 100 kts and you turn into wind and now you have a ground speed of 80 knots and so in relation to the ground you have slowed down. But he a/c has inertia [look it up]. It will not slow down instantly. That is where you IAS increases just for a few seconds. Not much and other errors affecting the accuracy of the asi may mask it [especially if the turn has a little slip in it] Gliding books discuss this effect in relation to entering thermals and changes in wind velocity. Your explanation doesn't relate to anything I wrote.

Sure mate, I'm not your instructor so I'll bow out

 

 

[turboplanner]

You could have fooled me Sapphire, you're the first person I've ever come across that flies an aircraft by groundspeed.

 

 

[Sapphire]

You could have fooled me Sapphire, you're the first person I've ever come across that flies an aircraft by groundspeed.

Sorry, cant help you.

 

 

[Gnarly Gnu]

Sapphire I thought you were referring to the "downwind turn stall" myth, I agree when doing a teardrop turn it should ideally be into any cross-wind there may be simply to minimise the turn radius.