cactusflyer

My Feedback: (4)

But Jack..... You are wrong! Once again I ask, What do you think makes the plane turn! Or as you put it, "relatively quick change in direction from traveling into or perpendicular to it...."

All of you mythmongoers present nearly the same scenario.....quick, abrupt, immediate, etc. turns? How do these take place. With the guy with the wind tunnel analogy, he wants to spin the model 90 or 180 degrees to see the Myth....how in the world does that apply to flying a plane full scale or model?

Luckily for me, early on, I was surrounded by super aero geeks that laughed at me when I blamed the myth......after all I just KNEW there was a downwind turn phenomenon. I read about in the modeling press.....more laughter directed my way that day at the flying field! One of the smart guys said to me " So John, how much ELEVATOR were you pulling in that downwind turn ?" I said " Not too much, the pane was really going fast on the dead stick base leg turn to final" . He smiled and the lightbulb turned on.....stick pressure is our only indicator of airspeed. Certainly not ground speed in any case....after that day back in 1974 I have never " noticed" the downwind turn phenomenon again.


Tailwinds,

John

jfetter

I think this can be summed up (for me anyway) with a question to you, and your answer. Question, would you say when you are flying perpendicular to a 20MPH wind, holding a fixed heading to a point on the ground and than make a fairly sharp turn downwind that your plane speeds up (ground speed) 20 MPH;

1.) Instantaneously?
2.) Within a second or two?
3.) Never changes speed relative to the ground?

Honestly, I am curious what you would say here...

Jack

chuckk2

"will affect lift momentarily"
Remember for the umpteenth time - - The plane is flying IN THE AIR, which is almost always moving relative to the ground.
Unless a gust, wind shear, or something similar is involved, the forces in the turn have nothing to do with the wind.
This INCLUDES LIFT!
How do I know? Well, there's this FAA thingie in my pocket that says I'm supposedly competent to pilot full size aircraft.

bjr_93tz

The whole change-of-direction argument relies on the forces changing the direction of flight coming from some non-airmass based source. Since the airplane can only generate forces relative to the airmass it's flying though then these forces are pilot/airplane commanded.

A control line model swinging around a person would experience a downwind turn (and an upwind one), while a free RC plane can't.

Seriously, if you were to walk around in circles on the back of a flat bed truck doing a steady 5mph you'd feel no need to speed up or slow down during your turn, but the bloke at the bus stop would see you speeding up and slowing down relative to himself. Downwind turn myth is really that simple..

highhorse

My Feedback: (2)

Jack,

Sorry dude. There's zero aerodynamic difference between quick turns, fast turns, steep turns, shallow turns, manned, unmanned, large, small, heavy, light or any other airplane with regard to the question "Is there a variance during a turn in speed/altitude/lift which is attributable to and varies with the wind direction?"

The answer is no, and observations to the contrary are proven to be attributable to optical illusion and/or gusts (which may be either + or -, but are in either case not relevant to the question at hand)

If you can't stomach the truth or simply can't get your mind around it...then perhaps YOU should unsubscribe and leave us to our errant ways.

cubcrasher

My Feedback: (6)

My plane tells me what it wants and I give it to it.

radfordc

My Feedback: (14)

Hmmm...sounds like my wife.

cubcrasher

My Feedback: (6)

grotto2

My Feedback: (2)

Due to the rotation of the earth, the speed of the earth's surface at the equator is about 1040MPH.
Under these conditions do I have to worry about my aircraft when turning from east to west?

TPL33

So that's why full sized aircraft take off and land into the wind? Controlled airports are required to use the runway "most nearly aligned with the wind". Your statement is ridiculous!

RZielin

My Feedback: (1)

Yes, of course that's why airports require the runway "most nearly aligned with the wind". It's certainly an important issue. Airports are on the ground. They're in the business of transitioning planes from ground to air and vice versa. It's only to shorten the takeoff and landing ground rolls (and to lower the ground speeds involved when the plane transitions from ground to air or vice versa). Why did you think any of us take off into the wind?

Once the plane is off the ground, it's free of interactions with the hard surface of the airport. It doesn't matter aerodynamically whether it's with the wind or cross wind or against it. Airspeed is the same in all directions. If you don't believe that, watch my videos linked in post #1247. It's only 15 min of your time that just might change your perspective forever. I hope it helps.

cactusflyer

My Feedback: (4)

Jack,

The posts above should clear things up for you. But since you asked me, here we go....First of all, the plane on the constant heading in the crosswind is TRACKING downwind. So it already moving downwind a bit. The rate of increase in ground speed in the downwind direction depends on the rate of turn (bank angle). As the plane rolls into the turn the heading starts to change,the downwind GS increases and the GS along the original past of flight decreases.....the plane reacts with the surrounding air. The turn is accomplished by changing the direction of the lift (vector vector). The wind cannot sneak up on the plane! The ground speed rate of increase depends on the rate of turn.

I suggest that you click on this link from in the earlier post and read the article from Flying magazine. It puts the whole thing in perspective.

http://www.flyingmag.com/pilots-plac...d-turns-really


Tailwinds

John

David Gladwin

So, you have done this thread to DEATH and still you have proven only three things:
1. Australian pelicans know (a lot) more about flying than those in the northern hemisphere and
2. The moon is made of green cheese, and
3. Aircraft are more educated about wind than some of those who fly them !

.......so why not move onto another myth, those involved in aircraft spin recovery, recently the subject of an excellent article in the EAA magazine !

I will be more than interested to passively read of the latest theories put forward by the usual RCU pundits, no doubt theories and practices missed by the real aviation community for the last 100 years !!

First just lets concentrate on "standard" spin recovery, ie that applicable to MOST aeroplanes, and for Don's sake you can discuss the Buggs Mueller method, for Pitts and Eagle fliers, later. !!

Fire away !!

David.

-JC-

My Feedback: (26)

Turbo, remember a smiley face behind every sentence that is sarcasm. Otherwise we may think you actually believe what you typed there :-) Believe it or not, a large percentage of americans actually think evolution is a hoax. Scary, but true :-)

flyinfool1

My Feedback: (2)

I recently earned my PPL. One of the most common maneuvers done during my training was slow flight. So we are up in a Cessna 172 with the nose pointed way up into the sky and the stall horn screaming because airspeed is on the verge of a stall. Stall speed is 54 mph normal landing speed is 65 mph. We would fly at 60 mph. We are flying circles and figure 8s in conditions from 0 to 25 mph wind. Once the plane was trimmed and the power level set to hold altitude, there was no problem making circles and figure 8s and never once did the plane try to fall out of the air as it repeatedly went from "upwind" to "downwind" while flying on the verge of a stall.
Also never once did my instructor mention any kind of warning about making the turn to the downwind leg of the pattern.

I guess it is true what I have been hearing on the news that there is a real danger that some modern airline pilots have lost or at least deteriorated the skills and ability to actually fly the airplane due to the computers and auto pilots doing everything for them all the time.

speed is life

David, saw a common Barn Swallow chasing a mosquito attempt a downwind turn which resulted in an upset and spin. This brings to mind; do you suppose that there is a difference in spin recovery technique between African and European Swallows?
- Mike

Selleri

Unladen or not?

jfetter

So I take it by your answer that you are saying the plane changes speed relative to the ground instantaneously then, yes? Remember, in my example you are holding a fixed course to a point on the ground, perpendicular to the wind direction, meaning you are not travelling with the air mass...

Jack

jfetter

Actually I'm not criticizing you or anyone else, which is why I said those that are should just unsubscribe and save us all the dramatics. I used my illustration because I've personally witnessed it in action, some don't seem to be getting the question fully but if you read it again, hopefully you will...

Jack

jfetter

No, my example says holding course perpendicular to the wind direction, to a fixed point on the ground, not moving to the side with the air mass at all. I am trying to give the most extreme condition to determine if you think the plane changes GS instantly or if there is any delay at all, simple as that...

Jack

chuckk2

The plane changes relative to the ground, not the air that it's flying in (depends on how you look at things, since relative to the air only, the plane can change with control input, power etc.). Instantaneous is not possible, due to the fact that the air doesn't move that fast.
Although, a wind sheer can be a quite rapid change. An accident at Lambert Field years ago sort of proved this.

Once (and only once, thank the Lord), I ended up almost upside down over a runway on takeoff. It turned out that the major cause was a combination of a roll effect caused by some hangers parallel to the runway, and turbulence from a departing airliner. The tower didn't say a thing ???
I rolled level, continued the takeoff and departed, reporting turbulence as I left.

Explaining what happens is much harder than understanding it by observation, both in and out of a plane.

JackD

My Feedback: (4)

Jack, reaching a groundspeed of airspeed +20 (flying directly downwind) will take exactly whatever it takes the plane to turn 90+ degrees. You were flying perpendicular to the wind, so you are crabbing (with respect to the ground), so it will be more than a 90 degree turn. As soon as that turn is completed, you will be flying at a groundspeed of airspeed + 20

hugger-4641

My Feedback: (6)

A large percentage of the world once believed the Earth was flat and at the center of the universe. Being in the majority does not make you right.

jfetter

Physics seems to elude some and this is just going in circles now. There is no doubt an aircraft moves with the air mass and doesn't feel the effect at all with any standard maneuver as it and the air are moving as one.. but it's also plain physics that an object changing directions (with mass and inertia), simply can't change speed instantaneously. I am not arguing this is a common effect or relevant in full scale aircraft flying normally, I am saying it is very possible to see this effect for an R/C pilot, always flying relative to his own position and not generally moving with the air mass but rather fighting it to maintain a constant heading/position relative to the ground. Accept it or not, it's physics and not too hard to demonstrate with a 3D plane in a stiff breeze. Remember also that an R/C pilot tends to keep the plane at a constant GROUND speed, not air speed, understand that and you'll get the gist of my argument...

Jack

PacificNWSkyPilot

My Feedback: (19)

I love all the "science" being passed around here.

You go faster downwind, because there's wind helping you, and reducing your drag. Going upwind, you're fighting it, and it increases your drag and fights you.

We take off into the wind because it increases our airspeed as far as the wings are concerned, but it's actually slower, because what's really being increased is the windspeed against the plane.

Let me put it more scientifically for you. Every time I ride a jet to or from the west coast and we get a nice tailwind, we get there an hour sooner. Sooner = faster. When we're fighting a headwind, we get there later. Later = slower.

If a Cessna flies at 80 knots against a solid 25 knot headwind, the speed it actually is moving is about 55 knots. If it's flying with a 25-knot tailwind, that Cessna is actually moving about 105 knots.

I'll let you guys take it from here.

~ Jim ~