MERGED power curve / floats posts

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Meatservo
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Re: MERGED power curve / floats posts

Post by Meatservo » Wed Nov 21, 2018 11:30 am

photofly wrote:
Wed Nov 21, 2018 11:11 am
Meatservo wrote:
Wed Nov 21, 2018 11:04 am
This is the exact equivalent of the many "crosswind landing" debates we see here.
Yes, it is. Everyone has their favourite way of doing that too, and anyone who does it some other way must be crazy, or suicidal, or incompetent, or all three.
I contend that there is only one way to properly land in a crosswind...
:-)
You may laugh, but if you really examine the two going notions, "sideslip" versus "kicking out the crab", the latter is simply a very last-minute application of the former. They both use ailerons into the prevailing wind to stop the aircraft from skidding and/or rolling downwind.

I'm not calling anyone crazy or incompetent. Most of the time when you listen to someone explain their technique, it turns out they are doing the same thing as everyone else but explaining it differently. Except, apparently, the Australians and New Zealanders.

Any crosswind technique that involves neutral ailerons at the point of touchdown, or the point of liftoff, is going to result in rubber skidding laterally on the takeoff surface. That isn't down to someone's opinion, that is physics. How much it skids,and for how long, depends on the weight and speed of the aircraft, the percentage of the relative wind that is lateral to the plane's direction of travel, and the ability of the tyres and the surface to permit skidding without upsetting the plane. On floats or skis, which I realize very few of you fly, that ability is "zero"

I have the opportunity at my job to conduct auto-landings. Many pilots would benefit from observing one of these in a crosswind. The aircraft uses ailerons to track the localizer- to touchdown. In the last fifty feet, it uses the IRS as reference to align the fuselage with the runway using rudder. Any drift off the localizer caused by this rudder input is countered by the ailerons as they pull the plane back. This causes the plane to touch down with the upwind wheels first, with opposite rudder holding it straight on centreline. There is a lower crosswind limit for autolanding, because the autopilot doesn't "kick out the crab" like a real pilot might if the crosswind was severe. The manual cautions pilots to avoid this skidding manoeuvre on dry pavement.

I don't know if this counts as "thread drift" or not, but thanks for the interesting and polite conversation.
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Re: MERGED power curve / floats posts

Post by photofly » Wed Nov 21, 2018 11:47 am

Any crosswind technique that involves neutral ailerons at the point of touchdown, or the point of liftoff, is going to result in rubber skidding laterally on the takeoff surface. That isn't down to someone's opinion, that is physics. How much it skids,and for how long, depends on the weight and speed of the aircraft, the percentage of the relative wind that is lateral to the plane's direction of travel, and the ability of the tyres and the surface to permit skidding without upsetting the plane.
If we're going to "physics" this, note that at the instant of lift-off, the weight on wheels is by definition zero, so the airplane can slide sideways without losing any rubber. Which is equivalent to agreeing with you that it must skid, but pointing out the amount of that skid can be "none". The idea of the pop-it-off technique is make the duration of the "marginal contact" as short as possible, which is the goal behind making the rotation speed slightly faster than normal.

While the amount of skidding should be kept to a minimum, we do allow some rubber to be worn away in all sorts of normal operations, that's why we have rubber tires that need replacing periodically, even with perfect flying technique.

I take your point that floats behave differently, and that the pop-it-off technique wont work on them. I asked why we don't use one-float-at-a-time on wheels, and it turns out that some people do. Result :)
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 8:01 pm

"sideslip" versus "kicking out the crab", the latter is simply a very last-minute application of the former.

If you watch an airliner on approach in a moderate crosswind, the wings are level throughout the whole crab procedure. WHEN the pilot fails to kick out crab at the last moment and correct any follow on effects, you may see a wing low overcorrection into the wind. That wasn't the intended maneuver but a failure to do the maneuver properly. Any airline pilots please correct me if I am wrong !

Any A/C can do the crab technique but the airliners with their huge weight compared to their lifting surface and low hung wing and engines MUST use crab technique most of the time in a crosswind

Crab with a C-150 is counter- productive If you do not make a perfect transition to landing, drift will mess up your landing and track and may set you up for an accident because you are now transitioning to the wing low method at the worst possible time .
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Re: MERGED power curve / floats posts

Post by C.W.E. » Wed Nov 21, 2018 8:08 pm

Crab with a C-150 is counter- productive If you do not make a perfect transition to landing, drift will mess up your landing and track and may set you up for an accident because you are now transitioning to the wing low method at the worst possible time .
If done properly here will be no drift thus no sideways movement.

I always use the crab into wind method for every airplane I fly.

If you have sideways movement at touch down using the crab and rudder /aileron decrab method and have sideways movement at touch down you are doing it wrong.
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 8:10 pm

Its perfectly fine in light/moderate steady wind to apply the "pop" it off technique, with immediate transition into the wing low offset ball method to track the centreline till assurance of no PLOP down will happen.

In high/ gusty x-winds that MAY get you into trouble and so flying off with the upwind wheel only is obviously favoured, then into the wing low tracking climb out.

Hint: If your car grill comes equipped with a freshly deposited seagull or Canadian goose as you approach the airport in your vehicle for your flight, it is probably safe to say its going to be a single wheel take-off !
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 8:15 pm

If done properly here will be no drift thus no sideways movement.
I suspect that CWE is actually Ace McCool therefore it is a perfectly correct statement.

Myself, being far from polishing Ace s shoes, muddle my way through landings and on the ODD occasion, makes something studio picture passable :roll: :roll:
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 8:26 pm

On floats or skis, which I realize very few of you fly, that ability is "zero"
Being a lower time float pilot ( 1500 hrs) the combination of nose low landing WITH drift is a deadly combination. very unforgiving in the floatplane arena. My fondest memories, ( apart from delivery flights) have been flying floats.
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 8:42 pm

his actually is how I take off in a crosswind. I thought I was doing it right. Controls into wind, the tail comes up, or the nose lifts, as the case may be, rotate, first one wheel then the other
In 2018, Teachers teach to the minimum. What you described may be referred to as an advanced procedure but normal in 1965
When I refer to Backside approaches, it is normal to me in certain conditions BUT is never taught because it is an advanced procedure.
We are in the same boat !

PS: If the weather aint CAVOK, students don't fly in these days :roll:
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 8:44 pm

Heck , In an earlier time flying in 200 and1/2 was ok VFR weather in the right conditions and area and in a stable WX system
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Re: MERGED power curve / floats posts

Post by C.W.E. » Wed Nov 21, 2018 8:49 pm

In 2018, Teachers teach to the minimum. What you described may be referred to as an advanced procedure but normal in 1965
In other words flight training today is grossly inadequate.

And who is responsible for this sorry state of affairs?
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 9:42 pm

And who is responsible for this sorry state of affairs?

Hmm, Lawyers? Pray tell me please cause I know not !
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Wed Nov 21, 2018 9:44 pm

Or perhaps our PC society who can never fail a student ( discriminatory ) or say it as it is ?
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Re: MERGED power curve / floats posts

Post by youhavecontrol » Thu Nov 22, 2018 3:54 am

A lot of people seem to love bashing instructors. As an instructor with 5 years and 2k hours of it, I can say that pretty much everything that has been discussed on this topic so far is taught and practiced with our students with regards to proper crosswind techniques and aircraft control on the back-side of the power curve.

The difference between my AvCanada posts and reality is that in reality my quality of instruction is regularly monitored and assessed through actual peer review, and my actions have consequences to my job. I have an in-house evaluation annually, a flight test average to maintain, teaching standards meetings, and an Exam every 3 years with Transport Canada. I have to be extremely careful with the words that I use when I teach and I have to ensure that my instruction will be carried out in a way that is not only safe, but actually beneficial to the student's current state of progress.

I'm not going to take a student with only 9 hours under his belt and start flying circuits in 20G30kt winds, just so he can get frustrated and overwhelmed... then later get accused of "time building" with the poor kid while he watched me do all the landings. It's true that some can take the side of caution too far, but If you've never been an instructor, you're "experienced" opinion of flight instruction doesn't hold much weight.
Heck , In an earlier time flying in 200 and1/2 was ok VFR weather in the right conditions and area and in a stable WX system
Yeah, more people died back then too... thinking they could handle that crap on their own.
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Re: MERGED power curve / floats posts

Post by Aviatard » Thu Nov 22, 2018 4:08 am

aeroncasuperchief wrote:
Wed Nov 21, 2018 8:42 pm
In 2018, Teachers teach to the minimum.
Nonsense.
aeroncasuperchief wrote:
Wed Nov 21, 2018 8:42 pm
PS: If the weather aint CAVOK, students don't fly in these days :roll:
More nonsense.
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Re: MERGED power curve / floats posts

Post by Meatservo » Thu Nov 22, 2018 12:55 pm

aeroncasuperchief wrote:
Wed Nov 21, 2018 8:01 pm
"sideslip" versus "kicking out the crab", the latter is simply a very last-minute application of the former.

If you watch an airliner on approach in a moderate crosswind, the wings are level throughout the whole crab procedure. WHEN the pilot fails to kick out crab at the last moment and correct any follow on effects, you may see a wing low overcorrection into the wind. That wasn't the intended maneuver but a failure to do the maneuver properly. Any airline pilots please correct me if I am wrong !

Any A/C can do the crab technique but the airliners with their huge weight compared to their lifting surface and low hung wing and engines MUST use crab technique most of the time in a crosswind

Crab with a C-150 is counter- productive If you do not make a perfect transition to landing, drift will mess up your landing and track and may set you up for an accident because you are now transitioning to the wing low method at the worst possible time .
OK, I will!

Like I said before, the perception of there being two distinct techniques is mostly a result of people explaining the
same thing two different ways.

The "crab" is always "kicked out". On a high-wing plane it might be "kicked out" some time before touchdown, and the aileron input necessary to control the resulting lateral drift results in the plane approaching the landing surface with a wing down.

On a low-wing plane with underslung engine pods, the crab angle is "kicked out" in the last twenty feet or so. Opposite aileron is still applied in order to keep the upwind wing from lifting, and also to control lateral drift. The wings are kept level or nearly level because the geometry of the plane requires it. On a more massive plane, very late application of the "cross controls" and smaller degree of aileron input into the wind is aided by the plane's mass and relatively high speed, which negates some lateral drift and also allows the aircraft to somewhat tolerate some lateral drift on touchdown, especially on wet runways. Just the way you might not de-crab a skiplane if landing on a slick, icy lake.

The result is the same however: in either scenario the plane touches down with so-called cross controls. The controls are deflected that way for the same reasons. Therefore my attitude is that it's not some entirely different technique, but instead it's the same technique, applied earlier or later as appropriate considering the type of aircraft and the surface condition.

I guess I can agree that a distinction exists in the sense that a plane may or may not be aerodynamically sideslipping immediately prior to the moment of touchdown. But, as photofly has pointed out, the only thing that counts in crosswinds is what the aircraft and the controls are doing when the aircraft is in contact with the runway.

The reason I disagree with the perception that there are two completely unrelated techniques is that I have seen pilots on light high-wing aircraft decide that they will practice landing "like an airliner". I would rather explain the whole process in common terms, with modifications to the technique as appropriate for the aeroplane type, rather than foster the perception that there is a whole new technique to learn at some future point. It's basically just about using ailerons and rudder together to control track, heading, and side-loading on the gear, in a timely fashion, to a greater or lesser degree depending on the aircraft type.

Here are some comments on various "airliners":

The manual from a popular transport category low-wing twin-jet aeroplane recommends a wing-low touchdown up to about 26 knots of crosswind component, after which it recommends a partially crabbed touchdown in order to avoid further bank angle which may result in wingtip or engine pod strike. This manual states that while zero sideslip landings are possible with the fuselage crabbed as necessary, this isn't recommended on dry runways due to directional control and gear side-loading limitations.

The manual for another popular, similarly-sized transport-category jet with a high wing recommends a wing-low sideslip touchdown right to the maximum recommended crosswind of 35 knots.

The manual for yet another popular commuter-category jet with a long, highly swept wing and fuselage-mounted engines (therefore pretty stubby landing gear) recommends a wings-level touchdown with lots of downwind rudder just prior to the moment of touchdown. It does however specifically mention the significant amount of simultaneous upwind aileron necessary to keep the wings level and the gear firmly stuck to the runway during this manoeuvre. In fact, even this aircraft will touch down slightly upwind-wheel-first in high crosswinds: This is directly from the manual: As rudder is applied the aircraft will tend to roll in the direction of the rudder input. To counter this, simultaneous input of rudder and opposite aileron is required to keep the wings level. In this wings level condition there will be some sideways drift. A slight, into wind, wing down should control this sideways motion.

I don't see two distinct techniques here, I see a continuum incorporating surface condition, wind intensity, and aircraft design.

I realize I'm simply arguing semantics here. I assure you I land and take off the same way as everyone else on every aircraft I have ever flown. I am simply communicating my opinion that the whole thing might be easier to teach if we stop regarding the art of crosswind runway manoeuvres as two distinct approaches to the same problem. Any technique you discuss for one aircraft type is going to be dangerous to apply on another aircraft type if modifications are not made to the technique.

Sorry for the long post.
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Re: MERGED power curve / floats posts

Post by C.W.E. » Thu Nov 22, 2018 1:10 pm

Crab with a C-150 is counter- productive If you do not make a perfect transition to landing, drift will mess up your landing and track and may set you up for an accident because you are now transitioning to the wing low method at the worst possible time .
I do not agree.

As long as the airplane is tracking straight down the centre line and is longitudinally lined up with the centre line as the wheels touch the runway inertia will keep it stable.

Of course if a pilot does not have the airplane handling skills to do that kind of landing they could lose control and wreck it.

It all comes down to a pilots skills level.

I used to like wet ice landings because there was no need to kick it straight on touch down, you can just keep it pointed into wind and it will slide to a stop in a straight line.
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Re: MERGED power curve / floats posts

Post by CpnCrunch » Thu Nov 22, 2018 2:13 pm

C.W.E. wrote:
Thu Nov 22, 2018 1:10 pm

I do not agree.

As long as the airplane is tracking straight down the centre line and is longitudinally lined up with the centre line as the wheels touch the runway inertia will keep it stable.

Of course if a pilot does not have the airplane handling skills to do that kind of landing they could lose control and wreck it.

It all comes down to a pilots skills level.

I used to like wet ice landings because there was no need to kick it straight on touch down, you can just keep it pointed into wind and it will slide to a stop in a straight line.
I find it more natural to transition to wing down at about 50ft in a small plane, as that seems to give more precise control over lateral drift and feels more natural and is more stabilized. If you're comfortable landing a 150 in a gusty crosswind and land within 1ft of the centreline and no lateral drift at touchdown using the kick method, then that's great.
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Re: MERGED power curve / floats posts

Post by C.W.E. » Thu Nov 22, 2018 2:58 pm

I find it more natural to transition to wing down at about 50ft in a small plane,
Could that be because that was the way you were taught?
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Re: MERGED power curve / floats posts

Post by C.W.E. » Thu Nov 22, 2018 3:19 pm

If you're comfortable landing a 150 in a gusty crosswind and land within 1ft of the centreline and no lateral drift at touchdown using the kick method, then that's great.
I am comfortable doing it that way because it works best for me.

I find it easier to stay aligned with the centre line using crab than slipping into wind especially in changing wind conditions on approach and landing.
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Re: MERGED power curve / floats posts

Post by CpnCrunch » Thu Nov 22, 2018 4:06 pm

C.W.E. wrote:
Thu Nov 22, 2018 2:58 pm

Could that be because that was the way you were taught?
I can't really remember to be honest. I think I was taught both methods, but I just find the wing down method easier and more natural. I crab to about 50ft and then transition to wing down.
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Re: MERGED power curve / floats posts

Post by C.W.E. » Thu Nov 22, 2018 5:54 pm

There is nothing wrong with your technique especially in that it is what you are most comfortable with.

I can't remember if I ever used the slip on approach method as my teachers taught me the crab method and pointed out how natural crabbing s as you are flying with the controls balanced and not sitting at an angle to your flight path and being pushed sideways in the seat.

However we all have different likes and dislikes and as long as safety is not compromised what ever technique works for each of us is O.K.
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Re: MERGED power curve / floats posts

Post by aeroncasuperchief » Thu Nov 22, 2018 6:03 pm

Aviatard wrote:
Thu Nov 22, 2018 4:08 am
aeroncasuperchief wrote:
Wed Nov 21, 2018 8:42 pm
In 2018, Teachers teach to the minimum.
Nonsense.
aeroncasuperchief wrote:
Wed Nov 21, 2018 8:42 pm
PS: If the weather aint CAVOK, students don't fly in these days :roll:
More nonsense.

OKAY, It looks like I got told ! :o
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Re: MERGED power curve / floats posts

Post by C.W.E. » Thu Nov 22, 2018 6:38 pm

While we are on the subject of what they are taught I would like to comment on the most annoying things they are not taught based on what I observed during my flight training career.

Using brakes to control taxi speed and not reducing power.

Chasing the airspeed needle in the climb resulting in a roller coaster path.

Failure to level off properly.

Inability to judge height above the runway when landing.

Those were the most common faults I observed.

Now I have a question.

How are they issued a PPL if they can not fly the aircraft properly?
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Re: MERGED power curve / floats posts

Post by youhavecontrol » Fri Nov 23, 2018 12:37 am

C.W.E. wrote:
Thu Nov 22, 2018 6:38 pm
While we are on the subject of what they are taught I would like to comment on the most annoying things they are not taught based on what I observed during my flight training career.

Using brakes to control taxi speed and not reducing power.

Chasing the airspeed needle in the climb resulting in a roller coaster path.

Failure to level off properly.

Inability to judge height above the runway when landing.

Those were the most common faults I observed.

Now I have a question.

How are they issued a PPL if they can not fly the aircraft properly?
If I had a dollar for every time I had to say, "reduce the power FIRST before applying the brakes to slow down," I could probably afford an extra vacation every year. Every item you listed is most definitely taught by good instructors at least... but after that PPL license is in their hands, it's anyone's guess how long it takes for dumb habits to show up again. I often hop into the Seminole with students and have to re-teach them how to taxi, use trim, level-off... all that stuff. For some reason, it's a new plane and they seem to think new rules must apply.
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Re: MERGED power curve / floats posts

Post by Blakey » Fri Nov 23, 2018 11:33 am

C.W.E. wrote:
Thu Nov 22, 2018 5:54 pm
There is nothing wrong with your technique especially in that it is what you are most comfortable with.

I can't remember if I ever used the slip on approach method as my teachers taught me the crab method and pointed out how natural crabbing s as you are flying with the controls balanced and not sitting at an angle to your flight path and being pushed sideways in the seat.

However we all have different likes and dislikes and as long as safety is not compromised what ever technique works for each of us is O.K.
I find the "slipping on approach" to be better when learning as it is merely a matter of increasing the deflection during the flare and landing. The only time I use it now is if the crosswind is such that I'm not sure I will have enough control authority to stay on the centerline after landing. If I need full control deflection to maintain track on approach, chances are I need to find another runway to land on!
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