Mishandling a forward slip

[Colonel Sanders]

The erroneous conclusion that people will
reach is that they will think that it's only
funky airplanes that you can play tricks
with unloading the wings, and not requiring
them to provide any lift.

Not true. Tex Johnston rolled the Boeing
707 prototype (367-80 for the pedants)
twice at the Seattle Hydroplane Races, at
1500 feet. When he was inverted, and
the wings were not providing any lift, how
did he not fall out of the sky and crash
and die? He entered the roll at low altitude,
remember.

[Jonathan Goldsmith]

The other tactic I advise, is to begin with a gentle angle of bank and if it looks like its not working then to increase to a greater one angles of bank.

That is terrible advice and one of the reasons pilots still fly into corners they cannot recover from. Observe someone which routinely flies near the edge of the air and notice the turn radius increases as they fly past an object.

[Shiny Side Up]

The other tactic I advise, is to begin with a gentle angle of bank and if it looks like its not working then to increase to a greater one angles of bank.

That is terrible advice and one of the reasons pilots still fly into corners they cannot recover from. Observe someone which routinely flies near the edge of the air and notice the turn radius increases as they fly past an object.

Please re-read carefully all of what I had to say and think through it. What corners that can't be recovered from are you talking about? I've yet to get into a turn that I couldn't roll out of.

Interesting how you can develop all sorts of forces from things other than the wing though:

Wings?! We don't need no stinking wings!

I could teach ONE thing to people it would be:

DON'T FEAR THE BANK ANGLE

Easier said than done. I would speculate that only a small proportion of human beings can truly lose their fear of bank angle - related to the fear of falling, one of the only two we're born with. Its possible that not all of us have an innate fear of bank angle and thus some probably make better pilots than others, at least ones capable of anything one might consider remotely aerobatic. This is one of the things I've found that training early (that is to say young) really helps with, since the older people tend to get, if they haven't overcame said fear earlier, the more ingrained it gets (combined with the fact that slips and falls beceome significantly more damaging the older you get, falling beceoms more worrisome).

[Colonel Sanders]

pilots still fly into corners they cannot recover from

What?

We are discussing turns. I think you must be talking about
recoveries from vertical downlines at low altitude. I routinely
am pointed straight down at 500 feet and 180 mph. Full
power and +6G and I am level at the surface. Great fun,
but most people don't do that and is distinctly outside the
scope of this discussion. I am not advocating that PPL's
attempt low-altitude vertical aerobatics. Even solo and
positive G only.

[Jonathan Goldsmith]

And I would assume you planned the pullout to start at 6g easing off near the end to arrive at the desired altitude. This is an example of a turn starting out gentle and increasing the bank when it became apparent it was not working out.

Consistent with the November 3, 2006 preliminary report, the NTSB's May 1, 2007 final hearing determined that "pilot error" caused the plane crash that killed Lidle and his flight instructor Tyler Stanger. The investigation was unable to determine which person was at the controls. The aircraft had only about 1,700 feet (520 m) of width in which to make the 180-degree turn, but this distance was effectively reduced to 1,300 feet (400 m) by the 13-knot (24 km/h) easterly winds that day. A bank angle of at least 53 degrees would be required to successfully execute a 180-degree turn in this distance. If the required bank was not initiated early then, as the turn progressed, the bank angle would have needed to have been increased, possibly resulting in an aerodynamic stall. The investigation was unable to determine if the plane was stalled at the time of the crash. An animation of the flight path combining radar data with a Coast Guard video of the East River was also presented.

[Shiny Side Up]

Sometimes I think people are having their own discussion in their head and forget that typing it down and hitting post is "outer voice".

Respectfully Mr Goldsmith, you haven't read the thread and aren't replying in the context.

[Jonathan Goldsmith]

You're right about that. Somehow this became bank angle and turns, not slipping. My apologies.

[pdw]

The example was a good one though.

[Colonel Sanders]

Yes, of poor decision making. The pilot should
have never ended up there, in the first place.

[Shiny Side Up]

You're right about that. Somehow this became bank angle and turns, not slipping. My apologies.

Appology accepted. Incidentally bank angles and turns are related to slips. Where and why do people slip airplanes? Why are slipping turns good but skidding turns bad? Incidentally I was referring to specifically how to make a turn and line up where one wants in relation to the runway, where the pilot should already be in a descent. Typically one might slip that turn to make it work a bit better too, but hazardously people skid it instead. Skids vs slips, sort of pertinent to "how do people mishandle slip".

[digits_]

So you can basically replace an unloaded wing with a broomstick with ailerons on , right ? I don't claim it is impossible to fly such an approach, only that at one point he has to leave this 'wing unloaded' equilibrium. Or does he land with an unloaded wing as well ? I don't see how this would be physically possible.

There's a teensy weensy bit of exaggeration going on, on both sides, I think.

Interesting how you can develop all sorts of forces from things other than the wing though:
http://www.youtube.com/watch?v=ZId2oiK1pr8

I think it is a bit off topic, but I'll ask it anyway because it's been bugging me. I really can't see any way in which an airplane can land without having any load on the wing from approach to touch down. Assuming your wheels are mounted on the bottom of your airplane, you'll have to get the wings level for touch down. That means, for them not to generate any lift, you'd need to have an extremely hight AoA, far beyond a 'normal' stall, or have a TAS of 0. Since you are flying/floating/falling the approach, your TAS is not 0, probably even quite high (?). That leaves the stall option. Still, I don't see how it's possible, not in practice, nor in theory to get a survivable rate of descend in such a way.

I like to be proven wrong, would be mighty cool if it were possible

[Colonel Sanders]

The people on this thread remind me of some PhD's
in mechanical engineering that I have met over the
decades.

If your car won't start, don't bother asking them
what's wrong, because they won't be able to figure
it out.

[pdw]

The slight left bank with right rudder implied in the opening thread is so very far from the zero AOA of wings-vertical flyby/approach of the Stewart Youtube example, though an eye-opening and realistic aerobatic example.

On final in the commercial or private GA aircraft is often a max gross cargo or pax situation, so you'd never be dreaming of a zero AOA, just holding as close to wings level in keeping loadfactor to a minimum .... knowing the chance of any upset recovery is close to nil.

[Colonel Sanders]

The erroneous conclusion that people will
reach is that they will think that it's only
funky airplanes that you can play tricks
with unloading the wings, and not requiring
them to provide any lift.

Not true. Tex Johnston rolled the Boeing
707 prototype (367-80 for the pedants)
twice at the Seattle Hydroplane Races, at
1500 feet. When he was inverted, and
the wings were not providing any lift, how
did he not fall out of the sky and crash
and die? He entered the roll at low altitude,
remember.

[DonutHole]

kinetic energy / ballistics?

[Colonel Sanders]

Good boy!

[pelmet]

The erroneous conclusion that people will
reach is that they will think that it's only
funky airplanes that you can play tricks
with unloading the wings, and not requiring
them to provide any lift.

Not true. Tex Johnston rolled the Boeing
707 prototype (367-80 for the pedants)
twice at the Seattle Hydroplane Races, at
1500 feet. When he was inverted, and
the wings were not providing any lift, how
did he not fall out of the sky and crash
and die? He entered the roll at low altitude,
remember.

Don't try it at work though...

"The Boeing 720B took off for a training flight from Frankfurt International Airport (FRA), Germany at 09:33. The crew reported reaching 13.000 feet at 09:38. The IFR flight schedule was abandoned and the crew continued VFR to carry out some training manoeuvres between VOR Kitzingen and the Roethenbach beacon. A complete roll was flown, but while attempting a second roll, the plane went out of control in the inverted position. The Boeing became overstressed, disintegrated and crashed in flames between Petersdorf and Forst."

http://aviation-safety.net/database/rec ... 19640715-0

[Colonel Sanders]

I suspect that pilot didn't have 1/100th of
the skill of Tex Johnston. When an unskilled
pilot screws up, it's not exactly a surprise.

This Luftansa pilot can't land in a crosswind, either:

[Rookie50]

I suspect that pilot didn't have 1/100th of
the skill of Tex Johnston. When an unskilled
pilot screws up, it's not exactly a surprise.

This Luftansa pilot can't land in a crosswind, either:

Yep. I'm sure from the sound you can hear, its only 10 knots or so too.

[Cat Driver]

Yep. I'm sure from the sound you can hear, its only 10 knots or so too.

You defend such mismanagement of an approach and out of control touch down?

[Rookie50]

Yep. I'm sure from the sound you can hear, its only 10 knots or so too.

You defend such mismanagement of an approach and out of control touch down?

No, I don't . Don't think it's landable, and should have been aborted sooner actually.

[akoch]

Wow!

I'm a low time pilot, but I'll say you are very very wrong. It is perfectly landable. This is why we go out and practice x-wind landings, right? Often asking the least favourable runway to make sure we "get it". Losing the upwind wing like this when we kick the rudder to align with the centreline is a beginner's mistake indeed. Guessing he did not practice enough of it. Perhaps more understandable at the PPL beginner level, no excuse for an ATPL pilot.

[Cat Driver]

I find this thread depressing.

How is it possible to have so many posts about a basic airplane handling issue?

Slipping is basic airplane handling...period.

[akoch]

To defend it - I don't find that stalling in a slip is something common, or something many people practice. When I had this question myself, I tried to research and ask around. Nothing came out of it, even some high-time pilots admitted they did not try stalling it in a slip. So I elected to just go and explore it a bit at altitude. And having done it, I understand better why most people don't bother - for all practical purposes it is not likely to happen.
On the other hand - I did hear comments from some people who were reluctant to use slip at all. That is odd and wrong indeed.

[Rookie50]

Wow!

I'm a low time pilot, but I'll say you are very very wrong. It is perfectly landable. This is why we go out and practice x-wind landings, right? Often asking the least favourable runway to make sure we "get it". Losing the upwind wing like this when we kick the rudder to align with the centreline is a beginner's mistake indeed. Guessing he did not practice enough of it. Perhaps more understandable at the PPL beginner level, no excuse for an ATPL pilot.

I'd say I'm very, very correct. I remember this video -- if I remember, the comments were, was that it was a 45 knot wind at a really high crosswind angle. Now I'm sure most out there would not run out of rudder and could land in that. Not me. The article below explains how the aircraft ran out of control authority due to the airbus design. Perhaps look at the facts, before judging the pilot. How would you do in 47 knots?

http://www.spiegel.de/international/ger ... 81796.html