Canadian fatal wingwalk stunt.

[Matthew Kane 1,343]

4 hours ago, tttocs said:

It's a fun little plane capable of some cool stuff, but ya can't fly it inverted.  And, BTW, it's a hoot to do fully developed spins in and is very easy to recover.

Have you ever done a spin without your instructor or on your own? I never got the nerve up to do one alone but in Canada it was a requirement for flight training. We had a trusty old 152 Aerobat in my old flight school as well. Loved that little plane 😎

Edited October 26, 2018 by Matthew Kane

[harrry 322]

Posted by mistake....

I saw a video of a 182 aeorobatics but did not realise it was a model.

 

but to make up for it this is relevant

 

http://www.airshowsa.org.za/articles/safety-forum/why-you-shouldnt-roll-an-aircraft-not-cleared-for-aerobatics.php

 

Edited October 27, 2018 by harrry

[FDEdev 955]

You can aileron and barrel roll basically every airplane without damaging it if you know what you are doing.

Things get interesting when complete idiots are trying to do snap rolls in biz jets! That's what a Hawker 800 looks like after doing multiple snap rolls:

http://photobucket.com/gallery/user/flyingpics/media/bWVkaWFJZDo1Mjk4MzIy/?ref= 

Edited October 27, 2018 by J35OE

[Chock 17,769]

A few skin ripples is getting off lightly if someone was trying to do flicks in an H 800. They were lucky not to rip the tail off the thing putting those kind of loads on it.

[FDEdev 955]

The Hawker is an extremely sturdy airplane, it can even survive direct missile hits!  

https://imgur.com/Cbvqpf9

 

[FDEdev 955]

42 minutes ago, Chock said:

A few skin ripples is getting off lightly if someone was trying to do flicks in an H 800. They were lucky not to rip the tail off the thing putting those kind of loads on it.

If correctly flown a snap roll doesn't put a lot of load on the airplane since it has to be performed at a rather low speed, well bellow V_A. It's nothing more than an accelerated horizontal spin.

[tttocs 301]

18 hours ago, Matthew Kane said:

Have you ever done a spin without your instructor or on your own? I never got the nerve up to do one alone but in Canada it was a requirement for flight training. We had a trusty old 152 Aerobat in my old flight school as well. Loved that little plane 😎

In the US, the FAA had shifted their emphasis to spin avoidance in training so spins weren't actually required.  My instructor was kinda old-school however and had all his students do them, so up we went and I'm glad we did.  This was shortly before my flight test.  It was a confidence builder and as I said, a whole lotta fun.

However, that session was the last time I flew the Aerobat and I never did spins again.  Formal aerobatic training was always on my wish list, but like so many things I never got around to it.

Scott

[Chock 17,769]

Yup, if correctly flown in an aeroplane stressed for it, a flick doesn't put an excessive load on the airframe, but it certainly does put a load on the tail, since you are inducing a sideways load on the rear of the aeroplane to get the thing to yaw quickly, thus stalling one wing only. It's usually not that the tail cannot withstand the amount of deflection which is the problem, it's that the load this induces can come on very quickly, i.e. far quicker than you'd normally make a rudder input for most normal maneuvers; a bit like if I pressed down on someone really hard with my fist as opposed to suddenly punching them with it, the amount of movement I apply might be the same for both things, but it's how quickly the force is applied which alters the result. If you imagine rocking a fence post, which is stuck in the ground, back and forth to break it, as opposed to slowly trying to bend it one way and hoping it will snap, this is exactly why the tailplane of American Airlines Flight 587 - the Airbus A300 which crashed over Queens NYC - lost its tailplane, it was basically levered off by having repeated loads put on it very quickly.

Whilst it can help a bit to sort of think of a flick roll as a 'accelerated horizontal spin', it's not really the same as what is going on in a traditional spin; the analogy only works, up to a point. A spin entry requires that both wings are stalled, since this is what induces the nose drop as both wings of the aeroplane stop flying, with the lift differential between the wings at the the point where they stalled asymmetrically producing the autorotation part of the spin. Whereas in a flick, you definitely only want one wing stalled, so you get the autorotation from that, but not the drop which would occur from having both wings stalled.

Rudder inputs will always put a sideways load on the tailfin, especially during a flick, since the rapid input of the deflection is what induces the yaw to make one wing stall before the other. If flown sloppily, it will all go a bit pear shaped and certainly if flown at too high an airspeed it can potentially go really badly, which is why if you look in even the pilot notes for things like the Supermarine Spitfire - an aeroplane designed to be flung around in combat - it actually states that flick maneuvers are prohibited!

You give it some up elevator before kicking the rudder on in a flick, in order to get the wings close to the critical angle, it is then the large and rapid rudder deflection which causes a lift differential to make just one wing stall, but unlike with a spin entry, you don't actually want both wings to stall, since it is the lift from the wing which is still flying that induces the roll. The tricky part is that ideally, the rudder deflection is applied when the input from aft elevator is at its peak effect-wise, which isn't the same as the wing being at the critical AoA, it's when the effect of the pull up itself is at its peak as the pull up rises to the point where a break with lots of yaw on will stall one wing cleanly and not the other one. This is the bit people cock up and the bit which needs practice, and why pilots can risk putting too much rudder on at the wrong speed in an attempt to really force the maneuver if they don't understand all the mechanics behind what they are trying to achieve, which is almost certainly what was occurring to over-stress the airframe in that pic of the business jet with a load of skin rippling.

[John_Cillis 2,406]

8 minutes ago, Chock said:

Yup, if correctly flown in an aeroplane stressed for it, a flick doesn't put an excessive load on the airframe, but it certainly does put a load on the tail, since you are inducing a sideways load on the rear of the aeroplane to get the thing to yaw quickly, thus stalling one wing only. It's usually not that the tail cannot withstand the amount of deflection which is the problem, it's that the load this induces can come on very quickly, i.e. far quicker than you'd normally make a rudder input for most normal maneuvers; a bit like if I pressed down on someone really hard with my fist as opposed to suddenly punching them with it, the amount of movement I apply might be the same for both things, but it's how quickly the force is applied which alters the result. If you imagine rocking a fence post, which is stuck in the ground, back and forth to break it, as opposed to slowly trying to bend it one way and hoping it will snap, this is exactly why the tailplane of American Airlines Flight 587 - the Airbus A300 which crashed over Queens NYC - lost its tailplane, it was basically levered off by having repeated loads put on it very quickly.

Whilst it can help a bit to sort of think of a flick roll as a 'accelerated horizontal spin', it's not really the same as what is going on in a traditional spin; the analogy only works, up to a point. A spin entry requires that both wings are stalled, since this is what induces the nose drop as both wings of the aeroplane stop flying, with the lift differential between the wings at the the point where they stalled asymmetrically producing the autorotation part of the spin. Whereas in a flick, you definitely only want one wing stalled, so you get the autorotation from that, but not the drop which would occur from having both wings stalled.

Rudder inputs will always put a sideways load on the tailfin, especially during a flick, since the rapid input of the deflection is what induces the yaw to make one wing stall before the other. If flown sloppily, it will all go a bit pear shaped and certainly if flown at too high an airspeed it can potentially go really badly, which is why if you look in even the pilot notes for things like the Supermarine Spitfire - an aeroplane designed to be flung around in combat - it actually states that flick maneuvers are prohibited!

You give it some up elevator before kicking the rudder on in a flick, in order to get the wings close to the critical angle, it is then the large and rapid rudder deflection which causes a lift differential to make just one wing stall, but unlike with a spin entry, you don't actually want both wings to stall, since it is the lift from the wing which is still flying that induces the roll. The tricky part is that ideally, the rudder deflection is applied when the input from aft elevator is at its peak effect-wise, which isn't the same as the wing being at the critical AoA, it's when the effect of the pull up itself is at its peak as the pull up rises to the point where a break with lots of yaw on will stall one wing cleanly and not the other one. This is the bit people cock up and the bit which needs practice, and why pilots can risk putting too much rudder on at the wrong speed in an attempt to really force the maneuver if they don't understand all the mechanics behind what they are trying to achieve, which is almost certainly what was occurring to over-stress the airframe in that pic of the business jet with a load of skin rippling.

One thing I found different in real life vs. a sim was how atmospheric dynamics, such as chop, could yaw the aircraft and create side force on the airframe, which I could feel in the "seat of the pants".  Some aircraft were more susceptible to this than others, and flying trikes I did not feel it at all since one only has the wing and no airframe for side forces to be exerted on.  Also did not notice this in the sailplane rides I have been on, since those aircraft have skinny airframes without much side area to them.  Also never noticed this much in heavy jets as they are of course, heavy and harder for chop to exert side forces against.  Puddle jumpers were more prone to this feeling, especially when their pilots landed them in gusty crosswinds.  For realism I try to fly my sims with variable wind speed and directions, which simulates chop as well as it can be simulated and makes landings much more interesting and a challenge.

John

[FDEdev 955]

9 minutes ago, Chock said:

Whilst it can help a bit to sort of think of a flick roll as a 'accelerated horizontal spin', it's not really the same as what is going on in a traditional spin; 

So Neil Williams (and other famous aerobatic pilots) are wrong….hmmm...

[Chock 17,769]

24 minutes ago, J35OE said:

So Neil Williams (and other famous aerobatic pilots) are wrong….hmmm...

If they were of the opinion that you stall both wings in a flick, then yes they would be wrong, but I should imagine they don't think that. They may have said that a flick is similar to a spin, but I doubt they don't understand the actual difference in what is going on.

[FDEdev 955]

6 minutes ago, Chock said:

If they were of the opinion that you stall both wings in a flick, then yes they would be wrong, but I should imagine they don't think that. They may have said that a flick is similar to a spin, but I doubt they don't understand the actual difference in what is going on.

No, they don't say that it's similar. The problem is the common misconception that, as you wrote, a stalled wing stops flying. This isn't the case and to understand what a stalled wing actually does is essential in understanding spins and snaps.

[Chock 17,769]

Okay, if we want to be strictly by the book accurate in terms of fluid dynamics and Reynolds numbers etc, then yes, a stalled wing does not completely stop flying, it suffers from a significant reduction in its lift coefficient when it hits on average about 15 degrees AoA or so for a typical aerofoil. But the reason I did not go into a massively long and irrelevant discussion about that is because that's got nothing to do with the point I was making, which is that a flick is induced by a difference in lift coefficient between the port and starboard wings, but not to the point where they are so badly stalled that it cause both wings to drop, i.e. it is not the same as a spin. You've got autorotation in a flick, but you've not got both wings also dropping owing to a significant loss of lift on both sides, since that would defeat the object of trying to induce only a rolling motion.

 

Edited October 27, 2018 by Chock

[FDEdev 955]

I still don't agree and I'm definitely staying with the explanation from guys like e.g. Mike Goulian (and my own aerobatic and aerodynamic experience/knowledge). 

Btw, I have no idea how it should be possible that both wings could drop at the same time. It's either the left wing or the right wing.

 

Edited October 27, 2018 by J35OE