Use of flaps during heavy crosswinds
- Thread starter Skyway
- Start date
clestudentpilot
Well-Known Member
I know not all, but some, especially Cessna's recommend flap settings for crosswind landings. While I know someone will ridicule me for saying it is only a "recommendation", that doesn't mean to ignore the information. Generally info isn't in a POH just because the typist is a union worker and had to read 10,000 words to get paid the full amount.
I also do realize that some POH's don't even mention crosswind landings. I know for myself, if I am unsure about a procedure to be used for a specific airplane, I think the POH is usually a pretty good place to start
tgrayson
New Member
It's a good place to start, but that doesn't mean that you have to end there. Being satisfied with that answer is simply memorizing procedures without understanding them. That isn't what this thread is about.
I personally took a 152 in at full flaps to gust 37, I never land without full flaps regardless of the wind or the gust. That said, I also don't use a slip technique to land, I crab and then straighten out in the flare while flying approach speeds of between 65-70.
Slip technique is great for teaching the student how much wing dip will be needed in the flare, so I use it for that. But for the approach phase the slip, IMO, is a pointless technique.
To the OP: Tgray gave you the only real issue as to why flaps in a crosswind can become an issue, that is the limit to rudder authority. The best reason I can give for you to tell your buddies is that flaps increase stability, they should all remember this from their ME training. We also know that an increase in stability means a decrease in control. The why is all speculation, but you might find this topic thread a good place to do some further research: http://forums.jetcareers.com/cfi-corner/89205-full-flaps.html
That said, if you don't use a forward slip and instead crab the aircraft till flare you shouldn't have any issues on rudder authority. It really depends on what technique your students are being taught to use.
As mentioned previously the use of partial flaps is certainly still a good idea to decrease stall speed without a drastic increase in drag. Some aircraft don't have a lot of power, like a 152, so if you get slow on a real gusty day and the student doesn't react with near full power quickly it can become dangerous quick. This is also what I typically teach my students, to stop at 20/25 flaps depending on aircraft instead of using the 30-40 range. But I never limit them to the use of full flaps or make them think it is some cardinal sin that will cause a subatomic eruption of the aircraft.
Maurus
The Great Gazoo
I have been in 15 knot xwinds in the 140 where I had to have full rudder to keep the plane aligned with the runway.
Only problem with that is the stronger the x-wind the more of a jerk the passengers will get when landing because of having to kick the rudder in right before touchdown. For purposes of controlling an aircraft, that technique works well.
MidlifeFlyer
Well-Known Member
I'm not sure what you are picturing but slipping all the way down final and jerking the airplane around 1 cm above the runway are not the only two things there.
If you only want to consider those two extremes, it's just as good a bet that passengers, especially those sitting behind the CG, would much prefer the coordinated flight down final and a 2 second jerk to sliding sideways in their seats and having their lunches slide sideways in their bellies (and ultimately out!) for an extended slip on 3-mile final.
Fortunately, we don't have to deal with those extremes and unless you land in a crab even the tightest 1 second "crab and kick" includes a slip (rudder to straighten and aileron to crosswind taxi position to stay on the runway after touchdown). Most pilots tend to find that happy medium of when to transition from the crab to the slip that balances both aircraft control and and passenger comfort.
Maurus
The Great Gazoo
The only way I could visualize 30+ knot x-winds in a 152 with full flaps was with a literal kick in the rudder immediately before touchdown. Otherwise yes, it is a slip, just later rather than earlier.
tgrayson
New Member
But not a necessarily stabilized one. If the aircraft were capable of a stabilized slip with that sort of crosswind, you wouldn't need to wait to the last second.
Exactly. Maurus, your forgetting momentum during the transition, you don't have to rush it so much, give it a shot. Wheels down around 45-55 knots if you approach at 65-75.
Isn't that a little fast for a 152? IIRC, POH says approach at 55kts, not land at 55 kts.
Of course it is, but it also means your under control in those nice gusty winds and won't have to fight it in with a slip. Also should a gust die you have adequate extra speed to keep from stall and allow for an easier go around. I have always been a strong advocate for "fly her to the runway" on a heavy crosswind day. Just my technique though, doesn't mean its perfect or even right but I haven't made any holes yet.
Bernoulli Fan
Controller
Be that as it may, I would like to commend clestudentpilot for going to the POH for answers to start with. Too many of my students would like to view the POH as a slightly unsavory and disorganized collection of incomprehensible characters.
Perhaps in the future clestudentpilot will be one of the rare breed who comes in for a new aircraft checkout already having looked through the POH for V-speeds and other limitations.
:clap:
BaronPete
Jaw Harp Troubadour
I fly a 150..so I'm left with even less power than you :whatever: Can you elaborate a bit on this point?
I'm still a noob student with a checkride approaching...Soaking up all I can!
Students tend to be shy about adding power when they get slow, in larger trainers like the 172 where they are 300 pounds under gross there is more than sufficient power. Aircraft like that, even if they are timid will usually still pull through fairly safely. They are also more stable and because they are heavier carry more momentum.
In your smaller 150 which if I remember they have 100 HP right? I know it is 10 less than a 152. Anyways in an aircraft like that you are typically flying near maximum weight with an low powered engine. In a high drag situation, such as full flaps, and running slow, consider around 50 knots slow on a gusty day, if you loose 10 knots to a gust you are now at 40 knots. Your first reaction will be a pull back loosing probably a few more knots and then adding power.
This is a very tough situation for a low powered aircraft to get out of: pitched at a high angle of attack, very slow, with a lot of drag. Full power may be needed to make that save but more importantly GET THE NOSE DOWN and that one step is what most new guys miss. The second those controls feel sloppy let the nose down, that nose will give you airspeed and reduce your AOA away from stall.
So the overall thing to learn is don't get slow. But if you do your first reaction should be to lower the nose followed by a good increase in power. Don't be timid with the power, too much is infinitely better than too little. If you give enough power when you lower the nose you won't even loose altitude, practice this with slow flight at altitude to see what I mean.
Here is how:
Tell your CFI you want to do some slow flight. Go up and get it slowed down and stable at say 40 knots and bring the power back to an approach power which will send you sinking. Let the descent stabilize than stop it by shoving the nose forward and jamming the power in, feel the aircraft seat push up on your butt, that is the sink rate reducing and the controls become more responsive from your airspeed going up. If you don't see it than have your instructor do it and watch the instruments (don't forget to listen and feel it as well, your a VFR guy
). Good luck bud.Tell your CFI you want to do some slow flight. Go up and get it slowed down and stable at say 40 knots and bring the power back to an approach power which will send you sinking. Let the descent stabilize than stop it by shoving the nose forward and jamming the power in, feel the aircraft seat push up on your butt, that is the sink rate reducing and the controls become more responsive from your airspeed going up. If you don't see it than have your instructor do it and watch the instruments (don't forget to listen and feel it as well, your a VFR guy
Or my personal favorite, "it's like a boat that's not up on plane, and too heavy to float. You have to keep the speed up to keep it from sinking. Let me show you the region of reverse command."
BaronPete
Jaw Harp Troubadour
Students tend to be shy about adding power when they get slow, in larger trainers like the 172 where they are 300 pounds under gross there is more than sufficient power. Aircraft like that, even if they are timid will usually still pull through fairly safely. They are also more stable and because they are heavier carry more momentum.
In your smaller 150 which if I remember they have 100 HP right? I know it is 10 less than a 152. Anyways in an aircraft like that you are typically flying near maximum weight with an low powered engine. In a high drag situation, such as full flaps, and running slow, consider around 50 knots slow on a gusty day, if you loose 10 knots to a gust you are now at 40 knots. Your first reaction will be a pull back loosing probably a few more knots and then adding power.
This is a very tough situation for a low powered aircraft to get out of: pitched at a high angle of attack, very slow, with a lot of drag. Full power may be needed to make that save but more importantly GET THE NOSE DOWN and that one step is what most new guys miss. The second those controls feel sloppy let the nose down, that nose will give you airspeed and reduce your AOA away from stall.
So the overall thing to learn is don't get slow. But if you do your first reaction should be to lower the nose followed by a good increase in power. Don't be timid with the power, too much is infinitely better than too little. If you give enough power when you lower the nose you won't even loose altitude, practice this with slow flight at altitude to see what I mean.
Here is how:
Tell your CFI you want to do some slow flight. Go up and get it slowed down and stable at say 40 knots and bring the power back to an approach power which will send you sinking. Let the descent stabilize than stop it by shoving the nose forward and jamming the power in, feel the aircraft seat push up on your butt, that is the sink rate reducing and the controls become more responsive from your airspeed going up. If you don't see it than have your instructor do it and watch the instruments (don't forget to listen and feel it as well, your a VFR guy
I gotcha, just wanted to make sure I was clear. The 150 is pitifully powered. You are correct in that it has 100HP total, but in reality probably only like 60 usable. I figure 100HP would be with the engine redlining on a "standard" day which we just don't have in Alabama. :crazy: I would guess that the usable horsies would be somewhere in the area of 60-70ish?
Anyway, when you say losing another 10 kts to a wind gust do you mean that the wind ballooned you nose high, thus draining some airspeed?
The HP question isn't my field, maybe one of the mechanics here can give some more information. Lower RPM is certainly less horsepower (work/time), but how much I would have no clue.
For your losing airspeed, I suggest you read into wind sheer a little bit. Gusty conditions imply wind will increase and decrease rapidly, right? So you are flying along at 50 knots with the wind at 20 knots. Now the wind picks up to 30, putting your airspeed at 60, to counter this you slow down back to 50. Now you are at 50 knots with 30 knots of wind and suddenly the wind dies back down to 20 knots, now your airspeed is 40 knots. That was the scenario I was referring too, pitch isn't a factor but instead the sudden loss of windspeed.
opcorn:, You want some more Coke?
Edit: P.S. Just make sure that whatever you do, put the damn airplane on the ground w/out bending it.
Could you pass the milk duds please