Correct, Ground Track = Gravity Well/Field of Earth which is where inertia lies. Inertia adds the 'ground track' component to the equation when you add an acceleration component off the wind. You can't leave gravity out of any energy equation.
Slowflight Question
- Thread starter Funkeruski
- Start date
Correct, Ground Track = Gravity Well/Field of Earth which is where inertia lies. Inertia adds the 'ground track' component to the equation when you add an acceleration component off the wind. You can't leave gravity out of any energy equation.
Secondary issue not under debate. The only issue is one of inertia vs acceleration with a changing aspect of the airframe to wind separate of the airframes inertial path. It is inconsequential, however it does exist.
Captain
Final Approach
Maybe if you better explained your theory of inertia and how it effects a plane turning from upwind to downwind. Describe an airplane in steady (smooth) air blowing 300kts over the ground.
What would happen to a C-150 doing steady turns over and over in such a condition. No wind shear and no turbulence. Just a steady wind blowing 300 kts. What happens to the plane?
What would happen to a C-150 doing steady turns over and over in such a condition. No wind shear and no turbulence. Just a steady wind blowing 300 kts. What happens to the plane?
Understand that due to inertia, when you add an acceleration off the wind, the heading of the airplane & therefore the aspect of the wing to the relative wind will lead the change in the path of the mass of the airplane. This is because the airplane travels within the Earths gravity which acts perpendicular to the center of mass of the Earth. Think of gravity as the atmosphere and inertia as the airplane where when you make that turn you skid. Gravity, water, and air all act in a similar fashion as far as drag dynamics go, however they operate at different and independent rates which causes skidding. It's this bit of skidding in a turn that causes an angular difference between the path of the aircraft and the relative wind to the wing. It's during this time where we are waiting for one path to reintegrate with the other in a steady state that we create a loss differential in lift as we head off the wind and pick up lift as we round into it. Magnetism acts similarly and produces the lead/lag turning errors. We operate aircraft in 2 fluids, gravity and atmosphere, boats handle in 3 fluids. Did that help?
Captain
Final Approach
Not really.
So, if the airmass is moving at 300 kts at 5,000 feet what happens to the plane doing circles (besides having the center of it's circle move across the ground at 300 kts)? Again...assume it's a steady 300 kts and there is no turbulence (or wind shear for those nit picking that angle).
btw, I know the wind never blows at 300 kts. I just find that using an extreme helps to make a point.
So, if the airmass is moving at 300 kts at 5,000 feet what happens to the plane doing circles (besides having the center of it's circle move across the ground at 300 kts)? Again...assume it's a steady 300 kts and there is no turbulence (or wind shear for those nit picking that angle).
btw, I know the wind never blows at 300 kts. I just find that using an extreme helps to make a point.
You have some very odd physics.
The strength of the wind is irrelevant for the most part, only the direction and quantity of the acceleration (turn) relative to into or away from the wind. A turn away from the wind will have a shift turning the wings away from the relative wind as the mass of the plane proceeds on it's inertial path. The angular difference is proportionately represent by the Gs you are pulling in the turn and is the same force interaction. Lomcevocks and tumbling maneuvers are the extreme examples of this effect.
If you're in SoFla, I'll keep explaining over beer, you can't see my hands and I can't explain it without, (anybody who has met me just blew Coke out their nose.
)
Last edited:
Captain
Final Approach
That's the point. If I'm in a 600 kt (see I doubled it for you) wind and I make a standard rate turn to the right then I simply turn to the right. Earth is flying by but my airplane does NOT care. It's just a turn. I do not lose lift as I turn to downwind and I suspect you are saying that I do.
It's a fact that I do not. I'll be happy to argue this point till the cows crow.
It's a fact that I do not. I'll be happy to argue this point till the cows crow.
Clark1961
Touchdown! Greaser!
- Joined
- Jun 7, 2008
- Messages
- 17,737
- Display Name
Display name:
Display name:
"Captain," you started the ****ing contest, I finished it. Wind shear can have an impact during just about any phase of slow flight.
Oldman
Pre-Flight
This makes sense to me.
Henning: Let's put it up for debate. Can shear turn your KIAS 95 into KIAS 75?
- oldman
skidoo
Line Up and Wait
Someone forgot to include the small effects of the rotation of the earth, and the centrifugal force (of the rotating earth) affecting the weight force and the fact that your aircraft weighs less at higher altitudes, etc...
But, for any significance, I tend to agree with Captains assessment, in reference to a moving, non turbulent, non shear air mass.
Wind is relative to something. It seems that what one person describes as wind is interpreted differently relative to something else. When describing something with wind, without including relative to what, then that leave it open for others to misinterpret what was meant. I think Captain was pretty clear as to what his wind description was relative to...
But, for any significance, I tend to agree with Captains assessment, in reference to a moving, non turbulent, non shear air mass.
Wind is relative to something. It seems that what one person describes as wind is interpreted differently relative to something else. When describing something with wind, without including relative to what, then that leave it open for others to misinterpret what was meant. I think Captain was pretty clear as to what his wind description was relative to...
I had shear take me from 115 to 60 (below stall) in an Ag Cat 3' off the deck with no altitude to give up for airspeed. I ended up upside down in the stand of oats; sent out to get the field fertilized before the front so it would get rained in. I almost beat the front, I was in the last half of the last pass on an uphill field, c`est la avion, I told him I didn't want to do it. I figure as long as I object or warn them of the likelihoods, if I tear up their stuff I'm in the clear.
I don't believe Captain has ever argued that shear effect does not exist. He's just not catching on that everything is a ground reference maneuver whether you like it or not. Gravity = Ground reference extended perpendicularly out to the edge of the planets 'gravity sphere of influence'. That gravity field is the plane/medium in which inertia reacts and that reacts a rate separate from the airframes relative direction to the wind.
Try this: Acceleration (g's) pulled off the wind physically will skid the back of the wing into the wind reducing lift. That help?
Last edited:
Captain
Final Approach
No. What you are arguing makes no sense to me. I recognize the words are English but the order you've selected to put them in makes no sense whatsoever.
Gravity pulls object towards the center of the earth. It's effect is proportional to your proximity to the earth. For our purposes we are all the same distance so gravities effect is the same regardless of altitude. Horizontal motion is not a factor in gravity. The only exception to that would be if your horizontal motion was enough to create a centrifugal force to off set you own weight. This is how an orbit works. Our little planes flying at 120 kts or 500 kts have a negligible effect in this aspect.
Gravity pulls object towards the center of the earth. It's effect is proportional to your proximity to the earth. For our purposes we are all the same distance so gravities effect is the same regardless of altitude. Horizontal motion is not a factor in gravity. The only exception to that would be if your horizontal motion was enough to create a centrifugal force to off set you own weight. This is how an orbit works. Our little planes flying at 120 kts or 500 kts have a negligible effect in this aspect.
Gravity is not a point, it is a field and acts similar to a fluid.
skidoo
Line Up and Wait
It is not really an exception. The factor is always there. What you are arguing about is the significance. Because in our cases, it is not noticeable and therefore its insignificant or negligible, but it is still there. The argument seems to center around insignificance... You are arguing about the practical application, where others may argue perhaps some insignificant fact, if indeed was a fact, which the argument turns into whether the particular insignificant portion is indeed a fact or not...
skidoo
Line Up and Wait
Of course it is not a point. It is a force. Please expand on your gravity/fluid idea...
Gravity creates drag on what it influences, the most most observable being light. The observed actions & reactions at the interface are very like those in fluid dynamics. Gravity also drags on space-time the same way.
That idea was proposed by Aristotle and was on the way out by the time of Galileo. Newton's theory formulated inertia as his three laws of motion, no gravity involved. This works fine for the flying we do.
Inertia gets involved with gravity only in the framework of general relativity and, except for our GPS, where the software handles the details, won't have any bearing on our flying. Certainly not enough to detect on a turn.
What interface? How can gravity drag space-time the same way when gravity is a bending of space-time caused by a mass?
That is the observation of gravity, the source is not known.
BTW again, I never said it mattered, I just said it existed, I always stated that it will not have any noticeable effect since the component is so tiny.
Last edited:
Sorry- it doesn't drag on itself. You haven't described the nature of the interface either.
You also haven't explained why you felt the need to invoke general relativity on the effects of wind on a turn. You were simply trying to confuse the issue with a non-sequitor.
Captain
Final Approach
Im not debating about anything of insignificance. My objection was when someone posted the plane needs to counter lost lift when turning out of a head wind. This is a common misconception as there is no lost lift and thats been my only point of contention.
I've been trying to suss out what Henning was referring to. That lost lift I described or something else. It appears it's something else and I couldn't care less about that effect. Also, I'd think if that was the argument (gravity and inertia and such) there would be reference to east or west headings as that would greatly affect the centrifugal forces acting on the plane.
Since the east / west thing has not been brought up I assumed he wasn't talking about that. One more time, my only position is that wind does not affect the plane except for ground track. I'm speaking of steady wind and not local turbulence or wind shear.
Actually I was trying to state why the downwind turn is a myth and where it came from. Adding the gravity well of the Earth was a way of introducing the separation of the aircraft's aerodynamic vector path with its inertial vector path and showing how you can change the angular perspective of the relative wind to the wing slightly ahead of changing the flight path causing a marginal loss of lift.
Told you, beer and you can see my hands and it will become clear in 6 seconds.
Last edited:
Don't worry. Neither does he.
gismo
Touchdown! Greaser!
I'm afraid it would require more beer than I'd care to drink at one sitting to accept your notions that "gravity creates drag" or that an airplane turning in a steady wind experiences any force or acceleration due to the wind. The effect of wind in a downwind turn has zero basis in fact other than the increase in groundspeed as the tailwind component increases which can be incorrectly perceived as an increase in airspeed.
The simplest approach to disproving any wind effect when turning is to consider the difference between an airplane turning in still air with the Earth moving below the air and airplane vs the same airplane turning in a homogenous airmass moving over the Earth. No matter how you look at it, the laws of physics will indicate no difference between those two scenarios and as long as the airplane remains at a fixed distance from the Earth's center of mass the effects of gravity will be constant on all headings during the turn.
Last edited:
Nope, the issue is to demonstrate loss of lift in a downwind turn due to inertia. I can demonstrate that in 6 seconds with the motion of one hand, 12 seconds using 2 hands to represent the divergent angles of 'path and point' if I have to go an extra step. It also becomes instantly apparent why this will never effect safety of flight in the slightest.
just make a video, post it someplace, and link it here.
Captain
Final Approach
I think I understand what he's trying to say. The fact that you can swirl your drink with no displacement while in an airliner going 500 kts sorta disproves his theory...but I do look forward to the video.
There is no loss of inertia when making a turn from headwind to tailwind...just to be on record again.
There is no loss of inertia when making a turn from headwind to tailwind...just to be on record again.
Anybody wants video they're welcome to come buy me a beer and shoot it.
12 seconds of video? Shouldn't take long. Just use your iPad to shoot it too.
gismo
Touchdown! Greaser!
Well, at least we can agree on that.
Bring yours
Why? You're the one that said it takes 12 seconds if we could see your hands move. You've already spent more time trying to weasel out of it than it'll take to actually prove your point (if you can).
Skylane81E
Final Approach
Or bring your butt up here and I've got beer.
Why? Why would I? Why should I more to the point?
I understand that there is a difference between the direction the plane is pointing and the plane is traveling when you make a turn and the harder you make the turn the more difference there is and this creates an angular difference between the wind and the wing which when turning down wind will cause a slight reduction in lift and turning into the wind will create a slight increase. I already know that skidding motions cause divergence between angles of pointing and progress and this changes the alignment of the wing cord to the relative wind.
Because you said you could explain it if we could see you hands move. I merely suggested how it could be done.
I don't think anyone is buying the bolded part. You're not explaining something well or you are wrong.