Wing down during final approach.
I started this thread to ask why so many pilots side slip all the way down the final approach
And I can do a crab or a wing down, but I happen to prefer wing down even though I have to teach crab if I am working to the French PPL syllabus.
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My miserable opinion after just 250hous is that any aircraft is crabbing to some extent wherever it is going, except directly into or out of any wind. I've never flown big stuff but I can't see that size makes all that much difference apart from response time? As for this transition thing I tend to try to "square it up" as late as possible, just as the wheels start to bend the grass is best, but certainly nowhere near 300feet. Then it seems it is aileron down rather than wing down cos the wheels are on the ground.Nice to see Chuck back. Your sort of experience is in short supply.
Last edited by Crash one; 2nd Feb 2014 at 11:06.
I had switched to sitting out this one, as I am not sure I am qualified. But I do recall, years ago, discussions with the chief instructor of my first soaring club. He was an advocate of touching down in a slip. John started out in B17's during the war. His early airline experience was piston and he transitioned to jets like many of his peers. He felt he knew where the engines were and how much wing down he could do without harm. He was not big on the crab and kick method.
I did my 10 hours of acro training in a Pitts S2A. That instructor was a little younger. He was flying P51s at the end of the war but didn't make it overseas. Later he was training the young jocks who flew in Korea. We spent a bunch of time doing landings, including heading to the big airport for hardtop and crosswind. That was all wing down. I think it would take a leap of faith for either the pilot, or especially the instructor to get the timing right in the Pitts to kick it out at the last minute. This is especially true at my skill level.
I know I will not try it in the C140 I rent. I would be willing to be shown by somebody covered by insurance. Personally I like the slow motion touchdown, or takeoff, where nothing is hurried and all control inputs are slow and steady. I like to prolong the touchdown as long as possible, a slow tradeoff of wings vs wheels bearing the weight.
Bryan
I did my 10 hours of acro training in a Pitts S2A. That instructor was a little younger. He was flying P51s at the end of the war but didn't make it overseas. Later he was training the young jocks who flew in Korea. We spent a bunch of time doing landings, including heading to the big airport for hardtop and crosswind. That was all wing down. I think it would take a leap of faith for either the pilot, or especially the instructor to get the timing right in the Pitts to kick it out at the last minute. This is especially true at my skill level.
I know I will not try it in the C140 I rent. I would be willing to be shown by somebody covered by insurance. Personally I like the slow motion touchdown, or takeoff, where nothing is hurried and all control inputs are slow and steady. I like to prolong the touchdown as long as possible, a slow tradeoff of wings vs wheels bearing the weight.
Bryan
dash6, Smokey,
You don't need to transition to wing down to stop any sideways drift. If you hold the crab throughout the round out & hold off the aircraft will continue to track down the runway. As the nose rises to the landing attitude you feed in rudder to align the fuselage with the runway.
Applying rudder will not change the direction of travel of the aircraft, certainly not in the couple of seconds it takes for the aircraft to run out of energy & touch down. Crosswind or not, the aircraft will continue to track down the runway after you put in the rudder. The only thing you need to do with the ailerons is keep the wings level.
You don't need to transition to wing down to stop any sideways drift. If you hold the crab throughout the round out & hold off the aircraft will continue to track down the runway. As the nose rises to the landing attitude you feed in rudder to align the fuselage with the runway.
Applying rudder will not change the direction of travel of the aircraft, certainly not in the couple of seconds it takes for the aircraft to run out of energy & touch down. Crosswind or not, the aircraft will continue to track down the runway after you put in the rudder. The only thing you need to do with the ailerons is keep the wings level.
The amount of drift will be proportional to the strength of the x-wind component, the inertia of the aircraft and the length of time that the x-wind has to act on the aircraft.
In certain circumstances this may well be negligible, as you suggest, but with a light aircraft in a strong x-wind it is most assuredly not trivial!
FBW
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It's just using one of the tools available to you in the later stages of the approach. Nothing wrong with side slip, it's very useful to be able to do it effectively and safely, and is a skill that should be practised regularly.
Obviously it's not appropriate in all aircraft, and even more obviously you wouldn't use it while cruising.
This video gives a nice view of the slips that are available. How many do you use?
Obviously it's not appropriate in all aircraft, and even more obviously you wouldn't use it while cruising.
This video gives a nice view of the slips that are available. How many do you use?
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RNT11, loving that video, especially the epaulettes.
Flying as I do out of a military airfield, we don't do big circuits. Sometimes I go to other airfields, fly a circuit which avoids local villages &c, then compare it to the noise abatement diagram in the clubhouse and find I've just flown INSIDE the villages they say to go OUTSIDE.
And that's in a spamcan - it could be tighter still in something more sporty...
Flying as I do out of a military airfield, we don't do big circuits. Sometimes I go to other airfields, fly a circuit which avoids local villages &c, then compare it to the noise abatement diagram in the clubhouse and find I've just flown INSIDE the villages they say to go OUTSIDE.
And that's in a spamcan - it could be tighter still in something more sporty...
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Flying as I do out of a military airfield, we don't do big circuits.
Excellent video. I am a small pattern kind of guy. Was the cub guy a slip or crab on final advocate though? I am unsure.
I think you are confusing track with heading. If you align the aircraft so that you are flying the runway heading, a crosswind will indeed drift the aircraft sideways while it is still airborne.
The amount of drift will be proportional to the strength of the x-wind component, the inertia of the aircraft and the length of time that the x-wind has to act on the aircraft.
In certain circumstances this may well be negligible, as you suggest, but with a light aircraft in a strong x-wind it is most assuredly not trivial!
FBW
The amount of drift will be proportional to the strength of the x-wind component, the inertia of the aircraft and the length of time that the x-wind has to act on the aircraft.
In certain circumstances this may well be negligible, as you suggest, but with a light aircraft in a strong x-wind it is most assuredly not trivial!
FBW
Here's the crucial bit: applying rudder does not change the direction in which the aircraft moves through the air. The direction of travel through the air will continue to be towards the windward side of the runway, add in the effect of the wind & the aircraft will continue to track down the runway centreline, even if the wings are level. It's an aircraft, not a boat. The rudder does not turn the aircraft, not at 2,000', not at 6".
(OK, if you shove in a bootful of rudder & keep the wings level, an aircraft will gradually, slowly, eventually change direction, but we're talking about the last second or two of flight here. There isn't enough time for the rudder to change the direction of travel at the end of a crabbed approach.)
OK, propswinger, I see your point.
If you keep the crab on all the way to touch down then I agree, you would be tracking the runway centreline but touching down with side loading.
In your scenario, the facing of the aircraft is changed by rudder, which does not change the direction of travel of the aircraft, just the direction it's facing, so that you land with the aircraft aligned with the direction of travel.
All well and good, but my point is that after removing the crab angle, there's a period of time when the aircraft is now drifting sideways - pointing parallel to the runway, but developing a lateral component due to the X-wind.
Depending on the strength of the x-wind component, the inertia of the aircraft and the length of time that the x-wind has to act on the aircraft, this may be insignificant enough not to be a problem - as you suggest - but on the other hand it may be very significant indeed.
FBW
If you keep the crab on all the way to touch down then I agree, you would be tracking the runway centreline but touching down with side loading.
In your scenario, the facing of the aircraft is changed by rudder, which does not change the direction of travel of the aircraft, just the direction it's facing, so that you land with the aircraft aligned with the direction of travel.
All well and good, but my point is that after removing the crab angle, there's a period of time when the aircraft is now drifting sideways - pointing parallel to the runway, but developing a lateral component due to the X-wind.
Depending on the strength of the x-wind component, the inertia of the aircraft and the length of time that the x-wind has to act on the aircraft, this may be insignificant enough not to be a problem - as you suggest - but on the other hand it may be very significant indeed.
FBW
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All well and good, but my point is that after removing the crab angle, there's a period of time when the aircraft is now drifting sideways - pointing parallel to the runway, but developing a lateral component due to the X-wind.
EUREKA!
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All well and good, but my point is that after removing the crab angle, there's a period of time when the aircraft is now drifting sideways - pointing parallel to the runway, but developing a lateral component due to the X-wind.
I see there to be 3 methods:
1. Slip final through the flare & hold off until both mainwheels are on the ground
2. Crab final through the flare & hold off, yaw in flat turn to align the aircraft a bare instant before both mainwheels touchdown.
3. Combination: Crab final until at some point a transition to a slip is made, leading to a slipped landing. Where that transition is can vary. Some start it prior to the flare - even a few hundred feet AGL - others as they flare, and yet others just prior to landing as an addition to the crab method.
My preference is a combination technique, starting the yaw & wing down as I flare. I don't like a slipped final because of the added drag (unless I want extra drag for some reason) and unpleasant side forces for my pax. I found that a pure crab method relied too much on a precision timing and if misjudged resulted in either landing still with some crab not yet removed, or a drift starting if slightly early and needing some wing down anyway to prevent the drift. A gust could also interfere with the timing and need some wing down anyway.
In Islanders in Shetland the rate of yaw just wasn't sufficient to allow a crab only method to work in the really strong winds (gale, strong gale & storm force). By the time the aircraft was part way aligned it would start to drift. Even using asymmetric power to increase the yaw rate wasn't always sufficient. The end result was that I'd yaw at max rate just before touchdown (with asymm. power if needed) while lowering a wing to counter the immediately developing drift.
1. Slip final through the flare & hold off until both mainwheels are on the ground
2. Crab final through the flare & hold off, yaw in flat turn to align the aircraft a bare instant before both mainwheels touchdown.
3. Combination: Crab final until at some point a transition to a slip is made, leading to a slipped landing. Where that transition is can vary. Some start it prior to the flare - even a few hundred feet AGL - others as they flare, and yet others just prior to landing as an addition to the crab method.
My preference is a combination technique, starting the yaw & wing down as I flare. I don't like a slipped final because of the added drag (unless I want extra drag for some reason) and unpleasant side forces for my pax. I found that a pure crab method relied too much on a precision timing and if misjudged resulted in either landing still with some crab not yet removed, or a drift starting if slightly early and needing some wing down anyway to prevent the drift. A gust could also interfere with the timing and need some wing down anyway.
In Islanders in Shetland the rate of yaw just wasn't sufficient to allow a crab only method to work in the really strong winds (gale, strong gale & storm force). By the time the aircraft was part way aligned it would start to drift. Even using asymmetric power to increase the yaw rate wasn't always sufficient. The end result was that I'd yaw at max rate just before touchdown (with asymm. power if needed) while lowering a wing to counter the immediately developing drift.
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T
All the examples here seem to be taildraggers often flapless ones at that and I can well see the reasons why crossed controls side slips etc become far more important but!
In strong winds if you need to bring in aeleron and rudder you have got it wrong in heavier singles, twins , etc.
The perfect situation would be bringing the aircraft straight at the point the wheels touch so anything else means you are hanging mid air holding off!
Ok none of us get it right So those techniques are required to stop the aircraft being blown across the runway. Being purist though and that is not required.
The other option is to fly it on especially in strong winds and not to sit there attempting to hold off but basically to put it down.
Maybe not a chairmans landing but a firmer arrival. In such winds the last thing you want is to be hanging in there 6 feet off the runway waiting for the aircraft to sink.
Pace
All the examples here seem to be taildraggers often flapless ones at that and I can well see the reasons why crossed controls side slips etc become far more important but!
In strong winds if you need to bring in aeleron and rudder you have got it wrong in heavier singles, twins , etc.
The perfect situation would be bringing the aircraft straight at the point the wheels touch so anything else means you are hanging mid air holding off!
Ok none of us get it right
So those techniques are required to stop the aircraft being blown across the runway. Being purist though and that is not required.The other option is to fly it on especially in strong winds and not to sit there attempting to hold off but basically to put it down.
Maybe not a chairmans landing but a firmer arrival. In such winds the last thing you want is to be hanging in there 6 feet off the runway waiting for the aircraft to sink.
Pace
Last edited by Pace; 3rd Feb 2014 at 10:54.
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Nice video but did you notice that it was dead calm? The only time the grass moved was when the plane's wing wake caused it (at time 30 sec.)
I suspect he taxies out of the hangar like that...
I suspect he taxies out of the hangar like that...
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It was an excellent demonstration of an approach, landing and running down the grass with the tail in the air using the forward slip technique.
It is a very useful method of teaching airplane handling skills.
It is a very useful method of teaching airplane handling skills.