A teachable moment

[Cluemeister]

Did he steer off intentionally because he was out of runway, or because he lost control?

[Ed Cesnalis]

To the degree that Roger was steering I think he might have seen that he was going left where the planes where parked and allowed it to happen.

 

Andy said the parked planes were too close but that looks like a bit of telescoping creating that illusion.

[Roger Lee]

He still had runway. He had room to clear planes just like the others. He panicked and grabbed brakes to fix his long fast landing and just quit steering. We talked several times about his landing. If you watch the video closely you can see all the tattle tale signs.

[FlyingMonkey]

The runway length was not the problem, but the surface definitely contributed.  I have landed my CT on 1500ft strips, but I probably wouldn't land on one with a humped surface like that.  The CT is very easy to get squirrelly on the ground, and an uneven surface like that is kind of asking for trouble.  Maybe if the strip was long enough and you could pick a relatively flat section...

 

On those short strips, you have to be going slow or you eat up too much distance before the airplane will settle down.  Short and rough surfaces are when you should be consciously thinking you want to come in slower.  Something telling on that video is to see how much runway is *behind* him on touchdown,  hard to say for certain with the angle, but I'd guess 500ft or more.  You can't give up that much on a shorter runway.

[Ed Cesnalis]

... The CT is very easy to get squirrelly on the ground ...

 

Really?  I have more than 1,000 landings in my CT and I have not experienced that at all.

 

squirrelly is an imprecise term, what are you saying exactly?  I would interpret that to mean that a lot of corrective input is needed to maintain directional stability?

 

If your landings are on and track the centerline the roll-outs are non-eventful.  I can't help but think that squirrelly is the result of excess speed.

 

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My recomendation is to learn to land short so there is a taxi to the turn-off.  Use this remaining runway to practice taxiing / rolling out with your nose wheel elevated and all steering by your rudder.  Lower you nose-wheel for braking and turning at the turnoff.  If your landings are almost 3 point with the nose settling in a fraction of a second this is going to take some practice.

 

A soft landing at minimum speed is pretty but a greaser with an extra 15 kts is only pretty to the guy doing it.  

 

Most CT pilots land too flat, too fast and have no control over their nose wheel.  Most CT crashes aren't crashes but a flip over when the nose wheel hits the hole.

[FlyingMonkey]

I have 600 landings in the CT myself without bending anything, I might have been overly dramatic.  In a normal landing and roll-out, or taxiing, it's fine.  But as I was learning in the CT I had a few puckered moments where the airplane's narrow gear caused it to weight shift in a way that felt uncomfortable.  Once you get the feel for it it's not bad, but you can't go stomping the pedal to the stops when moving, either.    

[Roger Lee]

"I can't help but think that squirrelly is the result of excess speed."  

It has to do with lack off or over steering. You can taxi the CT on the ground at 80 mph and it is true. Speed may compound your issue, but it isn't the cause.

[Ed Cesnalis]

Taxiing a CT at 80mph should be thought of as flying while in contact with the ground.  You call it taxiing, do you have the nose wheel on the ground at that speed?

[Roger Lee]

During my test yes I did, but you are right it is more flying on the ground (since 42 would get me airborne) and keeping the stick forward  and the rudder at that speed has a lot of influence. How hard was the front wheel on the ground, I don't know because I believe rudder had more influence. This is why I love these debates. Few have ever gone outside the norms so speculation or charts reign. 

 

The point was speed didn't make me squirrely. It's all steering or pedal control. 

I fully agree slower is better, but steering is key and a 5-10 difference in speed should make no difference.

 

You control the plane and it shouldn't control you. 

[FastEddieB]

I began this thread to emphasize how much kinetic energy increases with excess speed.

 

I never took even high school physics, so my knowledge on these things is pretty sparse.

 

Can anyone more familiar with the science inform us as to the effect of speed on the centrifugal (centripetal?) force with the excess speed?

 

I have about 1,500 hours in taildraggers, much of it instructing transition courses. In all those hours I had lots of excitement, but I never got to witness an actual ground loop. While there could still be one in my future if I ever again fly tailwheel, I think it was my focusing on very low landing speeds that helped keep me out of trouble - the more speed on touchdown, the stronger the tendency to swerve. Clearly the effect is noticeably less in a nosedragger, but it's still a factor - as I think can be seen in the linked video above.

[Roger Lee]

A basic rule of thumb is as speed doubles the kinetic energy quadruples. ke=1/2m*v²

 

 

^Eddie,

 

^{I flew helicopters for a few years then to taildraggers for the first time. Because of my helicopter time I never really had much to do with the taildragger CFI. Helicopters are all about dancing on the pedals. You do what you need to do to keep things straight without over or under control and remaining calm when you failed the first two.}

 

I would land at different speeds and didn't have a ground loop. Speed may add to your problems once started, but steering either by too much or lack of gets you in trouble. Will speed cause a more pronounced ground loop due to extra energy, no doubt, but the speed didn't cause it. There are many taildraggers of different sizes that land at different speeds so speed isn't what causes the loss of control. It's pedal control and early recognition of impending issues and not getting behind that eightball and or over controlling. Failing to recognise you are swerving and correcting it without over controlling is the key.

 

A slow speed keeps the guy with poor pedal control down at a slower skill set speed and gives them more time to react and when they fail at that reduce the effects you caused to the airframe.

 

Can anyone ground loop, here is your absolutely. Yes

 

 

Swerving in a CT nose wheel aircraft is no different. Swerving comes from either lack of or too much steering.

I do agree it may hurt more with additional speed, but I tend not to land when there is a ground squirrel on the runway. You hit'em, they bite your front wheel, it goes flat, the nose swerves, you over correct because the squirrel won't turn lose and swerve off the runway, it goes into the ditch and flips the plane.

 

Darn squirrels. 

[Ed Cesnalis]

Roger,

 

You are correct, its not speed that causes the directional problem.  Speed is fine when your momentum is going down the runway center-line.  Where speed becomes a problem is when you try and correct and get back to the center-line.  It takes 2 turns to get back and speed will dictate how much of a correction you can make before your grip on the runway lets go or one of your mains comes up and wing tip goes down.

 

The experienced pilot that lands tracking the centerline won't struggle with a bit of excess speed but a weak pilot that has to correct to stay on the runway or to get back to the center might have a series of problems that wouldn't exist at minimum speed.

[Roger Lee]

"but a weak pilot that has to correct to stay on the runway or to get back to the center might have a series of problems"

 

You got that right.

Now you identified a big problem in the video crash I posted.

 

 

When I help people transition I try to keep them from pumping and moving the stick all over and holding it steady. Number one problem I see with most. The same with the pedals. No quick sharp movements. Make them small and easy. Usually very little input at speed makes a fair difference and make your correction sooner than later. .

[Anticept]

Angular velocity and translational velocity are 100% independent of one another. Speed has an effect only in so far as it can be converted to angular momentum.

 

That said, because the CG is behind the mains on a taildragger, once a ground loop begins, the aircraft wants to follow the tail. It's aggrivated by the fact that friction increases as the aircraft rotates and the wheels go sideways. As the aircraft turns, one wheel spins faster than the other, and I theorize that because it's the inside wheel spinning slower, its friction is a little higher as points of rubber stay in contact longer and tries to twist, further aggrivating the turning tendency. Plus, people react by slamming on the brakes, aggrivating it even more.

 

Also, think about it like this: from a physics standpoint, breaking is the same as trying to push a two wheeled wagon. It will want to turn around on you.

 

Nosegear airplanes have the CG in front of the mains. The airplane wants to follow the CG, so it is hard to ground loop. Braking is like trying to pull a moving wagon to a stop.

 

It's a lot more complex than this, but that's the basics of what I know about it.

[pointpergame]

Let me jump in with a slightly sideways question.   As a pilot with fewer than 200 hours and the last 100 dragging tail on a grass strip, I haven't really had a lot of "saving it" practice.     I can feel it when my J-3 starts thinking about swapping ends.    In my prior 400 landings there might have been only 3 or 4 times where proactivity prevented a ground loop. Maybe.   

 

    So here is a serious question from a serious student:   how might that hapless gentleman have gotten the experience he needed to avoid his over-controlling loss of control?   

[gbigs]

None of this incident shows a deficiency in technique or flying skill.  The plane still had runway, he turned off and hit a rock/debris.....end of story.

 

Piper PA-30 Twin Crashes, Sets House On Fire, Pilot Killed - Plane On Way To OSHKOSH  http://www.avweb.com/avwebflash/news/Airplane-Crashes-Into-House-Pilot-Killed-226590-1.html

[Ed Cesnalis]

 

    So here is a serious question from a serious student:   how might that hapless gentleman have gotten the experience he needed to avoid his over-controlling loss of control?   

 

This pilot's background was flying a Piper Cherokee with his feet flat on the floor.  You can get away with it in that plane, little adverse yaw and bullet proof gear.

 

He bought the CTSW but wasn't quite up to the transition into it from the Cherokee, the transition pilot was frustrated.  He could have developed good stick and rudder skills at first or later when he bought the CT but it never happened.

 

Big difference between your cub skills and his lack of tricycle skills.

 

Biggest thing any of us can do is to become proficient especially at landing at the lowest possible speeds.  Given that most CT major mishaps come from planting the nose gear in a hole and flipping over, a CT pilot could master control of his nose gear.

[Tom Baker]

Take it from an experienced tailwheel instructor who also teaches in the CT. The CT of course will land differently than the Cub, but if you treat the landings the same you will be in good shape.

[Roger Lee]

"The plane still had runway, he turned off and hit a rock/debris.....end of story"

 

I talked to him at length the day after. He didn't turn off the runway on purpose. He didn't want off the runway. He wanted to go straight and stop. He made errors that cost him or at least the insurance company about $75K. He had just dropped his insurance to $80K. The original estimate to repair was off almost $30K.

[gbigs]

"The plane still had runway, he turned off and hit a rock/debris.....end of story"

 

I talked to him at length the day after. He didn't turn off the runway on purpose. He didn't want off the runway. He wanted to go straight and stop. He made errors that cost him or at least the insurance company about $75K. He had just dropped his insurance to $80K. The original estimate to repair was off almost $30K.

 

Was his "inadvertent" turn off the runway due to improper flying skills or unstable landing?  That is what I argue with....if he had not hit that rock/debris he would not have flipped and the result would have been different.

[FlyingMonkey]

It all started with too much speed.  The rest snowballed from there.

[Ed Cesnalis]

When the observer comments 'bumpy, bumpy' on roll out, chances are the speed is too high.  Be kind to your airplane, slow down for bumps, in the air or on the ground.

[gbigs]

When the observer comments 'bumpy, bumpy' on roll out, chances are the speed is too high.  Be kind to your airplane, slow down for bumps, in the air or on the ground.

 

He was on a rocky dirt strip.  The speed is unknown...and on that kind of surface you could be taxiing at idle and feel the bumps.  I have taxied at 20kts with no issue in the CT on smooth pavement.

[Roger Lee]

"Was his "inadvertent" turn off the runway due to improper flying skills or unstable landing?'

 

Both

 Andy is correct,

"It all started with too much speed.  The rest snowballed from there."

It was one bad decision after another.  The very first mistake was going to a difficult runway with poor-fair landing skills.

 

 

If he hadn't quit steering, let go of some brake, had landed slower, had landed at the beginning of the runway and not panicked when he thought he would overrun he probably would have been okay and made the stop.

 

In the original clip I have you can see the wheels skipping off the dirt. They were locked up and he wasn't firmly on the ground so his only course of action at that very moment was reduce the brake pressure and steer, steer, steer and don't freeze up. He froze and the plane veered off to the left without any correction,.

 

When I take my wife out to the track I always tell her steer, steer, steer and never quit steering until that vehicle comes to a stop. She learned the hard way one day by spinning off the track completely out of control. Panic set in when she started to spin and then all thought process goes out the window.

[FlyingMonkey]

 

When I take my wife out to the track I always tell her steer, steer, steer and never quit steering until that vehicle comes to a stop. She learned the hard way one day by spinning off the track completely out of control. Panic set in when she started to spin and then all thought process goes out the window.

 

When I took vehicle operator courses as a Police Officer from professional drivers, they had a mantra they always hammered into us:  "Steering is *always* more important than braking."