Effect of Density Altitude on Crosswinds

[vintage cessna]

It can if you stop the slipping turn after a small flight path change and then continue on a straight slipping non-turning path. Crap, I keep writing as if people actually make an effort to READ. But as I posted in another thread, this is nothing but folks spinning comments attempting to prove others have no grasp of physics. Nothing more that can be done. It's been fun, but it's getting old. Keep spinning if y'all want. Ciao.

Let me see of I have this right, and we'll say there is zero wind. The aircraft is cross controlled and that begins a slipping turn. You stop the slipping turn ( I'm not sure how that is accomplished yet) and you find yourself displaced from the original flight path. On the new flight path you can slip straight ahead. Since you are slipping straight ahead and not turning you can remain on the new flight path. In a cross wind landing, how would this compensate for drift?

 

[CharlieTango]

Let me see of I have this right, and we'll say there is zero wind. The aircraft is cross controlled and that begins a slipping turn. You stop the slipping turn ( I'm not sure how that is accomplished yet) and you find yourself displaced from the original flight path. On the new flight path you can slip straight ahead. Since you are slipping straight ahead and not turning you can remain on the new flight path. In a cross wind landing, how would this compensate for drift?

Once you are off the centerline you can recapture it with 2 slipping turns.

When not turning the yaw offsets the bank and not turn, to make the small turn add or subtract some aileron while keeping the nose down the runway. It feels like you are drifting sideways that is why we believed you could drift sideways.

 

[vintage cessna]

Once you are off the centerline you can recapture it with 2 slipping turns.

When not turning the yaw offsets the bank and not turn, to make the small turn add or subtract some aileron while keeping the nose down the runway. It feels like you are drifting sideways that is why we believed you could drift sideways.

So, IOW's , if one were to try to hold a slip on final, there is really no point in that because it doesn't stop the drift. You will continually need to make slipping turns to maintain track. So I assume when you finally will land, just before touchdown, you need to make a slipping turn into the wind?

I'm not necessarily saying this is wrong, but the only source that I have checked,the FAA Airplane Flying Handbook, says that in a slip there is forward movement as well as movement in the direction of the slip, and there is no turn. Do you have another source you could refer me to that describes it the way you do?

 

[vintage cessna]

A“
sideslip
” is entered by lowering a wing and applying
just enough opposite rudder to prevent a turn. In a
sideslip, the airplane’s longitudinal axis remains par-
allel to the original flightpath, but the airplane no
longer flies straight ahead. Instead the horizontal
component of wing lift forces the airplane also to
move somewhat sideways toward the low wing.
[Figure 8-12] The amount of slip, and therefore the
rate of sideward movement, is determined by the bank
angle. The steeper the bank—the greater the degree of
slip. As bank angle is increased, however, additional
opposite rudder is
required to prevent turning.

That is from the FAA Airplane Flying Handbook. Is that just a bunch of bologna?

 

[CharlieTango]

So, IOW's , if one were to try to hold a slip on final, there is really no point in that because it doesn't stop the drift. You will continually need to make slipping turns to maintain track. So I assume when you finally will land, just before touchdown, you need to make a slipping turn into the wind?

I'm not necessarily saying this is wrong, but the only source that I have checked,the FAA Airplane Flying Handbook, says that in a slip there is forward movement as well as movement in the direction of the slip, and there is no turn. Do you have another source you could refer me to that describes it the way you do?

My source is this thread, once presented with the correct take it became obvious.

No you don't have to do any additional turns once established on the centerline in the slip, except in the real world where crosswinds tend to come with shear and you will have to do 2 more little turns after you loose the center-line due to shear or judgement.

 

[vintage cessna]

My source is this thread, once presented with the correct take it became obvious.

No you don't have to do any additional turns once established on the centerline in the slip, except in the real world where crosswinds tend to come with shear and you will have to do 2 more little turns after you loose the center-line due to shear or judgement.

I might also add that the flight control surfaces become less effective as you slow, so that would require adjustment also.

 

[CharlieTango]

I might also add that the flight control surfaces become less effective as you slow, so that would require adjustment also.

This could be a balance thing, you have enough aileron to counter the rudder and maintain the 'heading' and as you slow both aileron and rudder loose effectiveness and the balance could be naturally maintained

 

[vintage cessna]

This could be a balance thing, you have enough aileron to counter the rudder and maintain the 'heading' and as you slow both aileron and rudder loose effectiveness and the balance could be naturally maintained

I know, and it will work out provided the wind has also diminished as you slow. If the wind hasn't also decreased it may require more control input.

 

[vintage cessna]

This could be a balance thing, you have enough aileron to counter the rudder and maintain the 'heading' and as you slow both aileron and rudder loose effectiveness and the balance could be naturally maintained

You fly a CT, right? I haven't flown a CT , but the other LSA's I have flown slow down at a very fast rate when you start to raise the nose on landing. To the point that even if the wind has diminished somewhat just above the runway you often need to increase control input to prevent drift.

 

[Vance Breese]

My source is this thread, once presented with the correct take it became obvious.

I feel that may be a mistake.
I have carefully read 382 posts and feel that most of the disagreement is about semantics or perspective.
In my opinion the way to avoid a debate about semantics is to define the terms in the beginning and stick to those definitions.
I feel that more people have read the FAA flying handbook than this thread so the FAA flying handbook would probably be a better source of definitions to avoid future misunderstandings.

 

[CharlieTango]

You fly a CT, right? I haven't flown a CT , but the other LSA's I have flown slow down at a very fast rate when you start to raise the nose on landing. To the point that even if the wind has diminished somewhat just above the runway you often need to increase control input to prevent drift.

Yes my CT runs out of energy very rapidly but running out of energy doesn't change my ground track it just makes me land.

I think less drift due to gradient will cause a need to adjust (small slipping turn).

 

[CharlieTango]

I feel that may be a mistake.
I have carefully read 382 posts and feel that most of the disagreement is about semantics or perspective.
In my opinion the way to avoid a debate about semantics is to define the terms in the beginning and stick to those definitions.
I feel that more people have read the FAA flying handbook than this thread so the FAA flying handbook would probably be a better source of definitions to avoid future misunderstandings.

The obvious problem here is the flying handbook chooses to describe side slips as thought the plane can fly sideways. It works in terms of using aileron to control drift and rudder to control heading but it isn't precisely correct.

 

[vintage cessna]

The obvious problem here is the flying handbook chooses to describe side slips as thought the plane can fly sideways. It works in terms of using aileron to control drift and rudder to control heading but it isn't precisely correct.

The obvious problem is you choose not to believe the plain language of the AFH. That is perfectly alright with me. I would just like to know that if the plane is not moving sideways in a slip and you are not turning, how in the world would a slip compensate for drift?

 

[Silvaire]

I don't want to step back into this but I'll repeat one thing: look at your turn indicator when you are in a slip, if you were turning the rate gyro would indicate that.

 

[whifferdill]

how in the world would a slip compensate for drift?

It doesn't. Flight path cancels drift, slip simply makes for a smoother touchdown. It truly is that simple. You are cancelling drift while crabbing down final in coordinated flight, tracking the runway. If you're drifting downwind, then you need to adjust your flight path more into the wind by turning. Then if you slip, you are only yawing the nose to make the landing smoother, not adding any additional "drift cancelling" forces. That opposite aileron in the slip only keeps the airplane from turning downwind due to the rudder input, not to "fight the x-wind". If you skidded the airplane with rudder alone, the airplane would turn in that direction, wind or no wind. If you are slipping and drifting downwind, then you need to turn the airplane's flight path more into the wind to cancel drift, not try to slip "harder".

I don't suppose we're making any progress? We were able to help Charlie Tango in this thread after a long discussion. Do you still think I'm flat wrong, or are we just saying the same thing in a different way such that neither of us understand each other?

 

[Silvaire]

It doesn't. Flight path cancels drift, slip simply makes for a smoother touchdown...

That sounds good wiff but you wouldn't be on that flight path with the nose pointed in that direction if the slip weren't cancelling the drift. Look at your airplane doing a no wind forward slip to landing to lose altitude. The airplane is flying laterally in reference to the longitudinal axis, a yaw string tells you that, the wind on the side of your face tells you that. In a crosswind you have the exact same control inputs with the exact same results.

...are we just saying the same thing in a different way such that neither of us understand each other?

Seeing that apparently none of us have crashed yet I suppose that's the best answer we're gonna get out of this thread.

 

[whifferdill]

That sounds good wiff but you wouldn't be on that flight path with the nose pointed in that direction if the slip weren't cancelling the drift.

Did you see my video where I went from coordinated flight, then slipped left and right with no flight path change? It made no difference that it was done in no wind. If I'm crabbed in a x-wind, flight path tracking the runway, and then slip without changing my flight path, how can you say that the slip is now the reason for my flight path? How does the slip all of a sudden cancel drift when a slip doesn't change your flight path, and I was cancelling drift before the slip? OK, no progress. Question asked and answered. That's all I came back here looking for. Smooth landings -

 

[Vance Breese]

The obvious problem here is the flying handbook chooses to describe side slips as thought the plane can fly sideways. It works in terms of using aileron to control drift and rudder to control heading but it isn't precisely correct.

Are you suggesting that an airplane can only fly in the direction it is pointed?

 

[CharlieTango]

The obvious problem is you choose not to believe the plain language of the AFH. That is perfectly alright with me. I would just like to know that if the plane is not moving sideways in a slip and you are not turning, how in the world would a slip compensate for drift?

The slip compensates for drift the same way a crab does. You slip/crab on a heading that produces a ground track that is similar to the runway's (extended) center-line.

 

[vintage cessna]

It doesn't. Flight path cancels drift, slip simply makes for a smoother touchdown. It truly is that simple. You are cancelling drift while crabbing down final in coordinated flight, tracking the runway. If you're drifting downwind, then you need to adjust your flight path more into the wind by turning. Then if you slip, you are only yawing the nose to make the landing smoother, not adding any additional "drift cancelling" forces. That opposite aileron in the slip only keeps the airplane from turning downwind due to the rudder input, not to "fight the x-wind". If you skidded the airplane with rudder alone, the airplane would turn in that direction, wind or no wind. If you are slipping and drifting downwind, then you need to turn the airplane's flight path more into the wind to cancel drift, not try to slip "harder".

I don't suppose we're making any progress? We were able to help Charlie Tango in this thread after a long discussion. Do you still think I'm flat wrong, or are we just saying the same thing in a different way such that neither of us understand each other?

I have understood everything you have said. The problem with you theory is, when it comes time to land. If you straighten out the nose with rudder, and as you say aileron doesn't prevent or compensate for drift, then you wil land with some drift and side load. I suppose if you did this at the last moment the drift wouldn't be much and the landing would be acceptable.

 

[vintage cessna]

The slip compensates for drift the same way a crab does. You slip/crab on a heading that produces a ground track that is similar to the runway's (extended) center-line.

What you are saying doesn't make any sense. In a slip the nose is aligned with the runway heading regardless of wind direction. In a crab your heading is to the left or right of RWY heading.

If in a slip and the nose aligned with the RWY, if the plane does not have a sideways movement, how would it not drift off course in a cross wind?

 

[FlySince9]

No, I surrender. As the Borg would say, " resistance is futile".

Oh don't stop now!

 

[whifferdill]

I have understood everything you have said. The problem with you theory is, when it comes time to land. If you straighten out the nose with rudder, and as you say aileron doesn't prevent or compensate for drift, then you wil land with some drift and side load.

If you crab down final and do nothing but straighten with rudder (no aileron, no slip), then you will start a slow turn in the direction of your rudder input, not drift due to the x-wind. There's a difference between turn and drift. Go up in your airplane and apply rudder while keeping the wings level with aileron. No need for wind. The airplane will start a slow, inefficient, and constant skidded turn. Same thing happens when you straighten out in a x-wind with rudder only. It is NOT the x-wind that starts moving you off runway track, assuming you were previously tracking properly in a crab.

And yeah, if you time it right, you can skid to straighten out the x-wind landing and touch down before the airplane has turned a significant amount away from the runway track. Some people land this way, though it's much easier in trikes than in tailwheel airplanes. It is literally "crab and kick", rather than "crab and slip".

 

[CharlieTango]

Are you suggesting that an airplane can only fly in the direction it is pointed?

You can yaw but that is an attitude change, to change your flight path you have to do a turn. To begin and end a drift 2 turns are required flying sideways is what it seems like, a visual illusion.

Look at this drift to centerline and notice the 2 turns in the ground track. If you add the turns to the drift between it seems like flying sideways but it isn't, planes need to turn twice they can't correct drift by flying sideways.

 

[vintage cessna]

Did you see my video where I went from coordinated flight, then slipped left and right with no flight path change? It made no difference that it was done in no wind. If I'm crabbed in a x-wind, flight path tracking the runway, and then slip without changing my flight path, how can you say that the slip is now the reason for my flight path? How does the slip all of a sudden cancel drift when a slip doesn't change your flight path, and I was cancelling drift before the slip? OK, no progress. Question asked and answered. That's all I came back here looking for. Smooth landings -

If you come out of the crab and then slip, and the slip does not compensate for drift, how would you remain on the same flight path? Are you relying on intertia?

Why not just come out of the crab wings level? You can do that in a manner that doesn't swing the nose around to the right.

 

[CharlieTango]

What you are saying doesn't make any sense. In a slip the nose is aligned with the runway heading regardless of wind direction. In a crab your heading is to the left or right of RWY heading.

If in a slip and the nose aligned with the RWY, if the plane does not have a sideways movement, how would it not drift off course in a cross wind?

it doesn't drift off course because the drift is compensated for by a flight path that produces a ground track that is similar to the runway center-line.

On one hand the you and the air mass are drifting across the runway but on the other hand your flight path is into the crosswind enough to cancel that. The icing on the cake is the sideways attitude that causes the gear to align (rudder authority permitting).

 

[vintage cessna]

You can yaw but that is an attitude change, to change your flight path you have to do a turn. To begin and end a drift 2 turns are required flying sideways is what it seems like, a visual illusion.

Look at this drift to centerline and notice the 2 turns in the ground track. If you add the turns to the drift between it seems like flying sideways but it isn't, planes need to turn twice they can't correct drift by flying sideways.

I'm going to get a visit from the SPCA for beating a dead horse here. I can tell you this, the FAA Airplane Flying Handbook has been around for a long time. I have never seen anyone challenge the basics that are in that book until I visited this forum. In the end it doesn't really matter as long as the right control inputs are used.

 

[CharlieTango]

If you come out of the crab and then slip, and the slip does not compensate for drift, how would you remain on the same flight path? Are you relying on intertia?

Why not just come out of the crab wings level? You can do that in a manner that doesn't swing the nose around to the right.

Some people do come out of the crab wings level and manage to get tires on the runway before too much drift develops.

Others transition to a slip and minimize side-loading.

 

[whifferdill]

If you come out of the crab and then slip, and the slip does not compensate for drift, how would you remain on the same flight path? Are you relying on intertia?

For you, "slip" is a red herring in this discussion. Flight path alone cancels drift. You can fly a constant flight path in coordinated flight, slipping left, or slipping right.

If you think left aileron in a left x-wind is what is cancelling drift, here is what you need to do - Fly crabbed and tracking the runway, and then apply a slip with LEFT rudder and RIGHT aileron. You will still be tracking the runway, and "cancelling" drift, but you will just be even more misaligned with the runway. Flight path still doesn't change. Have you ever considered this? Hint: don't actually touch down this way.

Why not just come out of the crab wings level? You can do that in a manner that doesn't swing the nose around to the right.

Post # 396.

 

[CharlieTango]

I'm going to get a visit from the SPCA for beating a dead horse here. I can tell you this, the FAA Airplane Flying Handbook has been around for a long time. I have never seen anyone challenge the basics that are in that book until I visited this forum. In the end it doesn't really matter as long as the right control inputs are used.

If the handbook wasn't challenged I would still be thinking that steady state crosswind actually impacts my aircraft as I drift into it. I now grasp the physics better.

Rudder authority produces only so many degrees of yaw before a turn develops and hence the limitation on crosswind capability. Its good to get that, at least for me.

 

[vintage cessna]

For you, "slip" is a red herring in this discussion. Flight path alone cancels drift. You can fly a constant flight path in coordinated flight, slipping left, or slipping right.

If you think left aileron in a left x-wind is what is cancelling drift, here is what you need to do - Fly crabbed and tracking the runway, and then apply a slip with LEFT rudder and RIGHT aileron. You will still be tracking the runway, and "cancelling" drift, but you will just be even more misaligned with the runway. Flight path still doesn't change. Have you ever considered this? Hint: don't actually touch down this way.



Post # 396.

Yes the flight path cancels the drift. In slip the airplane has a sideways movement component , that is why you don't drift.

What I have considered is that in a crosswind you land the airplane properly, you just don't know why you have. So , the discussion is purely academic.

 

[whifferdill]

Yes the flight path cancels the drift. In slip the airplane has a sideways movement component , that is why you don't drift.

Did you even read my post above? If the "sideways movement component" of a slip is what is cancelling drift, how is it that you can slip in both directions in a left x-wind, and still not drift off runway track?? Shall I shoot a video of this too? You are getting less argumentative, we must be getting close.

 

[Vance Breese]

The obvious problem here is the flying handbook chooses to describe side slips as thought the plane can fly sideways. It works in terms of using aileron to control drift and rudder to control heading but it isn't precisely correct.

You can yaw but that is an attitude change, to change your flight path you have to do a turn. To begin and end a drift 2 turns are required flying sideways is what it seems like, a visual illusion.

Look at this drift to centerline and notice the 2 turns in the ground track. If you add the turns to the drift between it seems like flying sideways but it isn't, planes need to turn twice they can't correct drift by flying sideways.

In my limited experience in fixed wing aircraft I found I could fly sideways through the air (uncoordinated flight).
I found the nose was seldom pointed at my destination so I feel I was flying sideways in relation to my ground track.
I am puzzled by your divergent perspective.

 

[vintage cessna]

Did you even read my post above? If the "sideways movement component" of a slip is what is cancelling drift, how is it that you can slip in both directions in a left x-wind, and still not drift off runway track?? Shall I shoot a video of this too? You are getting less argumentative, we must be getting close.

You can't slip to the right in a left crosswind and not drift off course.

Sure, I read your post, I just fundamentally disagree with it. I have posted a reference from a source material, you have not. So we will just agree to disagree.

 

[whifferdill]

You can't slip to the right in a left crosswind and not drift off course.

Oh man, this one is so easy. Next x-windy day, video will happen - even though you may disagree with what you see on video. So far, we have helped one person in this thread. To me, that is worth it.

 

[CharlieTango]

In my limited experience in fixed wing aircraft I found I could fly sideways through the air (uncoordinated flight).
I found the nose was seldom pointed at my destination so I feel I was flying sideways in relation to my ground track.
I am puzzled by your divergent perspective.

My nose seldom points at my destination, that is because of WCA not flying sideways through the air mass.

You are correct you can fly sideways relative to your ground track, that is due to the drifting air mass that you are flying within.

 

[vintage cessna]

Oh man, this one is so easy. Next x-windy day, video will happen - even though you may disagree with what you see on video. So far, we have helped one person in this thread. To me, that is worth it.

Ok, can't wait to see the video. Now that you have done your good deed for the day by helping CT, maybe you can help him with the DA issue.

 

[MAKG1]

My nose seldom points at my destination, that is because of WCA not flying sideways through the air mass.

You are correct you can fly sideways relative to your ground track, that is due to the drifting air mass that you are flying within.

You can fly sideways in no wind at all. It's a good proficiency exercise to adjust position on the runway in a low approach, all while keeping the nose pointed straight ahead.

 

[vintage cessna]

Some people do come out of the crab wings level and manage to get tires on the runway before too much drift develops.

Others transition to a slip and minimize side-loading.

One last thing CT. Do you see a problem with your logic and how you have contradicted what you have said before?

It is very possible to transition to a slip from a crab and not minimize side load but eliminate it.

 

[dtuuri]

You can't slip to the right in a left crosswind and not drift off course.

Oh man, this one is so easy. Next x-windy day, video will happen - even though you may disagree with what you see on video.

Well, you can certainly make a left turn while banked to the right, then after turning a certain amount stop and hold it in a forward slip. I suspect that's all the video will show.

dtuuri