Icon A5.. another crash Jul 27

If you are boating down a river and turn the boat around your boat speed relative to the water doesn't change.. the knot meter stays the same, I've had this happen in the Cape Cod Canal having to turn around.. sailboat at 6 knots current at 3

What I will notice is on descent or climb I've seen the indicated air speed suddenly change by as much as 20-30 knots if going through different air current layers. Descending into KMMH from 16,000 I've had the airspeed drop from 160 to 120 at 14K then from 120 up to 160 passing through 12K.. 700 ft/min VS mode

I guess part of this depends on how sharply you turn plane (since the airplane has its own inertia, etc) but I've done standard rate turns with 40 knot tailwinds that affect course by 60* and not noticed any difference in airspeed.. just a marked change in GS
 
SToL said:
I disagree but open to learning something new.

Lift and airspeed both will increase with a headwind and both will decrease with a tailwind.

This is one of the simplest methods used to determine wind direction. Turns that reduce airspeed or require increased power, are downwind turns, where as, turns that increase airspeed or allow reduced power, are into the wind.
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How does the wind change your airspeed?

Hint - it can’t.
 
SToL said:
I thought every pilot knew this.

Flying in no wind, your airspeed and your ground speed will be the same.
Flying into a headwind, your airspeed will be greater than your groundspeed.
Flying with a tailwind, your airspeed will be less than your groundspeed.
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Flying into a headwind, your airspeed will not change, your groundspeed will be slower.
Flying into a tailwind, your airspeed will not change, your groundspeed will be faster.
Flying in no wind, your airspeed will not change, your groundspeed will be the same.

If this were not true, then the things you just said every pilot knows could not be true, it’s what makes them true.
 
Palmpilot said:
Gusts or turbulence are a different subject. When you're talking about wind direction, you're talking about the direction that the air mass is moving relative to the ground. The movement of the airplane is controlled by thrust, drag, lift, and weight, not ground speed.
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I'm not arguing that the aircraft knows what the ground is doing. Stop trying to say that.

The ONLY thing the aircraft knows is how fast the wind is moving over the wing.

In a headwind, it's moving faster. In a tailwind, it's moving slower. If the tailwind is significant enough, you will have to compensate for it, either by increased power, or increased pitch angle.
 
luvflyin said:
I think there can be changes in airspeeds. ... But when you make the turn from one to the other there can be changes until your established straight ahead. There is some inertia to be overcome.
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There is no change in AIRSPEED when an airplane changes direction. There is a change in GROUNDSPEED dependent on wind direction relative to the direction of flight. These are two different frames of reference. You can prove to yourself this is true by flying standard rate turns in level flight. Your airspeed will never change, but you will drift downwind relative to the ground.
 
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aftCG said:
Is it still a good landing if you swim away from it
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Nice.. I like that. Yes?

chemgeek said:
Sailors understand the idea of relative wind, but pilots seem to struggle with this concept for some reason.
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Yeah, sailing is actually a great sport for learning about wind, airfoils, AoA, etc. When taking new people out there's this "fifth dimension" about keeping the boat on a heading relative to wind. Folks zone in on the compass and don't understand why the sails are luffing or the boat slows down and they're getting seasick

SToL said:
I thought every pilot knew this.

Flying in no wind, your airspeed and your ground speed will be the same.
Flying into a headwind, your airspeed will be greater than your groundspeed.
Flying with a tailwind, your airspeed will be less than your groundspeed.
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Yeah but turning around doesn't change your air speed just your groundspeed. Relative to the air the plane stays the same.. the air and the plane are part of the same mass
 
SToL said:
In a headwind, it's moving faster. In a tailwind, it's moving slower. If the tailwind is significant enough, you will have to compensate for it, either by increased power, or increased pitch angle.
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What if it's on a treadmill?

Flying with a 40 knot tailwind or 40 knot headwind doesn't require different power settings.. the plane will do 150 indicated or whatever.. only the GS changes

#aliens
 
**** poor takeoff planning meant unprepared pilot hit a tree that because it is larger than the FAA standard of 50’, self identified as a non-obstacle.

I posted elsewhere that Ozzy Man Reviews needs to add this one to one of his “Destination F***ed” compilations. LOL.

The lake looked plenty big if he had perhaps taxiied to where the cameraman was.

I can’t decide if I’m switching from clicking the sad emoji to the laughter emoji for the idiots crashing these things. It’s becoming cliche’ now.
 
chemgeek said:
There is no change in AIRSPEED when an airplane changes direction. There is a change in GROUNDSPEED dependent on wind direction relative to the directly of flight. These are two different frames of reference. You can prove to yourself this is true by flying standard rate turns in level flight. Your airspeed will never change, but you will drift downwind relative to the ground.
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Yeah. I get that. I understand it completely. But when there is a sudden change, unlike when flying standard rate circles, there can be. It doesn't last long. Read my post again
 
Someone on another forum is making a similar, if somewhat more nuanced, argument.

My response:

It’s momentum relative to what? The air mass or the ground?

Analogy...

You’re walking down the aisle of a train moving at a constant speed of 60 mph. You stumble and fall. Is it relevant to your injury likelihood whether you’re walking in the direction the train is moving or in the opposite direction?

In the case of a plane, the only thing that matters is its momentum relative to the air mass. In a 60 kt wind, a 100 kt plane could be moving over the ground at 40 kts into the wind or 160 kts flying downwind. In both situations the “lift” and stall likelihood are identical. The plane has no way of knowing what the ground is doing*. In your scenario, something would change momentum-wise if the plane started doing 360’s in that wind as the groundspeed went from 40 kts to 160 kts. It doesn’t. Under a hood you could not feel anything different from doing the same 360’s in still air.

Back to the ICON, as it made the right turn in an airmass moving left to right in the video, it would behave exactly as it would in still air. A wing does not know or care what the ground - or water - below it is doing.


*The only way to determine what the plane is doing relative to the ground is via navigation sources - or to look.
 
luvflyin said:
I think there can be changes in airspeeds. Yeah, the airspeed isn't going to be different when flying with a headwind vs flying with a tailwind. But when you make the turn from one to the other there can be changes until your established straight ahead. There is some inertia to be overcome. It would be momentary and would have to be a very tight turn to be significant. But if you're on the edge of a stall it might make the difference. The extreme example is you're flying into a headwind and the wind makes an immediate shift to a tailwind. You're airspeed is going to change until the plane overcomes it's inertia and gets stabilized.
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I think a lot of the confusion on this subject comes from people trying to do the analysis using a frame of reference that is attached to the earth's surface. However, it's not necessary to use that reference frame, and it complicates the analysis. The principle of special relativity says that you can get valid results using ANY unaccelerated reference frame to do the analysis. That is a principle of physics that has been experimentally validated many times over that past 100 years.

For a steady wind, it's much easier to see what's going on if you use a reference frame that is attached to the air mass instead of the ground. Doing that makes it immediately obvious that a turn in a steady wind affects the airplane in exactly the same way it does when the wind is dead calm. The only thing that changes is the airplane's track over the ground, but that has no effect on the airspeed as long as you are high enough to be out of ground effect.

(Whether the plane in this case was high enough to be out of ground effect, I'm not sure.)
 
SToL said:
I'm not arguing that the aircraft knows what the ground is doing. Stop trying to say that.

The ONLY thing the aircraft knows is how fast the wind is moving over the wing.

In a headwind, it's moving faster. In a tailwind, it's moving slower. If the tailwind is significant enough, you will have to compensate for it, either by increased power, or increased pitch angle.
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No. The only thing the airplane knows is how fast the AIR is moving over the wing. Wind has nothing to do with it.

Think about an air ballon. Once it leaves the ground it’s airspeed never changes, it is always 0, but it’s groundspeed changes based on the wind.
 
SToL said:
I thought every pilot knew this.

Flying in no wind, your airspeed and your ground speed will be the same.
Flying into a headwind, your airspeed will be greater than your groundspeed.
Flying with a tailwind, your airspeed will be less than your groundspeed.
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And what do you conclude from that?
 
I highly recommend the book stick and rudder to you guys that are struggling with this. He explains it excruciating detail. And there’s pictures. Lol
 
If you were aboard that aircraft, the airspeed indicator would not change in the turn, no matter where you did it in relation to the wind blowing past a pin stuck to the ground. You’re already flowing downstream with it.

The best analogy of why the downwind turn stuff doesn’t matter is a boat making circles on a river. To the observer on the shore, the boat is moving downstream. To the boat, it’s just making circles at the same speed.
 
SToL said:
Let's say you have a 45 knot headwind and your airspeed is indicating 45 knots. You are effectively hovering.

Without making any changes to airspeed or pitch attitude, turn downwind, what's going to happen?
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Your airspeed will still be 45, and your groundspeed will be 90.

I mean no offense by this, I’m just curious, do you have an ASEL, or only rotorcraft cert?
 
Salty said:
Your airspeed will still be 45, and your groundspeed will be 90
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Correct. And the wing won’t care. If there’s a bunch of tall trees behind you, you’ll get to the crash in the trees twice as fast as a no-wind scenario... but the aircraft doesn’t care.
 
Once you leave the ground you are moving with the mass of air. Just like the hot air ballon is. That’s why you drift off the runway in a crosswind as soon as you leave the ground. (if you don't correct for it)
 
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From reading this thread, I find it amazing that we don’t crash more often.

Relative to headwinds and tailwinds. (Not associated with wind shear) your AIRSPEED won’t change, your RATE of climb won’t change, your ANGLE of climb with change as GROUNDSPEED changes.
 
Knowing that the earth is flat... how does that affect airspeed vs ground speed?
 
FastEddieB said:
Someone on another forum is making a similar, if somewhat more nuanced, argument.

My response:

It’s momentum relative to what? The air mass or the ground?

Analogy...

You’re walking down the aisle of a train moving at a constant speed of 60 mph. You stumble and fall. Is it relevant to your injury likelihood whether you’re walking in the direction the train is moving or in the opposite direction?

In the case of a plane, the only thing that matters is its momentum relative to the air mass. In a 60 kt wind, a 100 kt plane could be moving over the ground at 40 kts into the wind or 160 kts flying downwind. In both situations the “lift” and stall likelihood are identical. The plane has no way of knowing what the ground is doing*. In your scenario, something would change momentum-wise if the plane started doing 360’s in that wind as the groundspeed went from 40 kts to 160 kts. It doesn’t. Under a hood you could not feel anything different from doing the same 360’s in still air.

Back to the ICON, as it made the right turn in an airmass moving left to right in the video, it would behave exactly as it would in still air. A wing does not know or care what the ground - or water - below it is doing.


*The only way to determine what the plane is doing relative to the ground is via navigation sources - or to look.
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Yeah. Momentum. Inertia. In the airmass. While comparing air speed to ground speed is one way to illustrate a point, it's not valid when discussing what is happening to the wing in the air and whether or not the angle of attack is going to change. Which happens at predictable air speeds for set weights and configurations. In the air, 'sudden' changes in wind speed and direction can affect the airspeed of the airplane until it's momentum, or inertia, pick a word, stabilizes it in the piece of air it is in.
 
luvflyin said:
Yeah. Momentum. Inertia. In the airmass. While comparing air speed to ground speed is one way to illustrate a point, it's not valid when discussing what is happening to the wing in the air and whether or not the angle of attack is going to change. Which happens at predictable air speeds for set weights and configurations. In the air, 'sudden' changes in wind speed and direction can affect the airspeed of the airplane until it's momentum, or inertia, pick a word, stabilizes it in the piece of air it is in.
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Changes in the wind slowed or direction is precisely what was NOT being discussed. The discussion is about turning doenwind absent shear or gusts.
 
luvflyin said:
...In the air, 'sudden' changes in wind speed and direction can affect the airspeed of the airplane until it's momentum, or inertia, pick a word, stabilizes it in the piece of air it is in.
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True, but that's a different situation from the pilot initiating a turn in a uniformly-moving air mass. We gotta keep the scenarios straight or we'll be lost!
 
My aircraft know nothing. Wind does not change airspeed unless the wind itself changes, as in gusts or shear. Once the airplane takes off, it is part of the airmass it is flying in.
 
Salty said:
Your airspeed will still be 45, and your groundspeed will be 90.
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Ugh, no it won’t. Flying into a 45kt headwind and indicating 45kts on the ASI is not going to equal a ground speed of 90.
 
Ryanb said:
Ugh, no it won’t. Flying into a 45kt headwind and indicating 45kts on the ASI is not going to equal a ground speed of 90.
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I think you should read his post completely. my post was answering his question.
 
Go up on a day with high winds aloft, and do some standard rate turns in complete circles, your airspeed will remain the same.. of course this does not factor gusts or shear just a stable air mass
 
SToL said:
I'm not arguing that the aircraft knows what the ground is doing. Stop trying to say that.
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We agree that the airplane has no way of knowing what the ground is doing. The problem is that the only way to know whether you're flying upwind or downwind is to know how the air mass is moving relative to the ground. The aircraft has no way of knowing that.

The ONLY thing the aircraft knows is how fast the wind is moving over the wing.
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The only thing the aircraft knows is how fast the RELATIVE wind is moving over the wing. Relative wind is not what is being referred to by the terms "upwind" and "downwind."

In a headwind, it's moving faster. In a tailwind, it's moving slower. If the tailwind is significant enough, you will have to compensate for it, either by increased power, or increased pitch angle.
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In a steadily-moving air mass, the relative wind is not affected by the direction or speed of the air mass relative to the ground.
 
Try it. Pick a day with a steady (not gusty) wind, and go fly in a circle, constant power and rate of turn. Does your indicated airspeed change anywhere through the circle? Don't look at the ground. Better, bring someone with you and do it under a hood so you really don't look at the ground.

Your airspeed won't change. Now, if you do look at the ground you'll see that you are steadily moving downwind, but the airplane can't tell that from the air around it.
 
I think it is safe to say that despite the high accident rate, Icon is still convinced that the product it is infallible, and treats them as such.. flying low and slow and maneuvering close to the ground requires a certain set of skills..
 
Palmpilot said:
True, but that's a different situation from the pilot initiating a turn in a uniformly-moving air mass. We gotta keep the scenarios straight or we'll be lost!
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Yeah. Your right. Not a thread for advanced aerodynamics.
 
These discussion airspeed/tailwind/etc always reminds me of my technical mechanics course back in engineering school. We got a daily problem to work and if you got them right for enough days, you could skip the midterm or final.

The prof had a collection of doozies to “stop you at the Goal Line” as he said. One I had once was to calculate the relative speed of a bug walking on a rotating turntable in a train traveling down a track to another bug flying in a car moving 90 degrees to the the train track. I died on the one foot line. Taught me everything I ever need to know about relative motion as in this case, airspeed vs ground speed.

Cheers
 
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