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Cross Wind Component

Sully73

Active Member
I am in phase one flight testing with my RV-4. I was faced with a 13 mph crosswind component today and found that I had to use all my rudder and some braking to keep it on the runway. Is this normal for a RV-4? I plan to re-check my rudder travel but I am asking if there is any thing else I should be doing?
I had full flaps and approach speed of 75 mph. Should I approach faster and with less flaps to sustain more airflow?
Any other suggestions?
Thanks in advance
BTW...I love my RV-4....
Jon
 
My experience with the -6 is that 15 knots direct is pretty much it for me. That's with the wing way down and lots of opposite rudder, maintaining those inputs all the way to walking speed. I'd say 13 knots and 15 knots are pretty much the same number, with the difference being a rounding error between wind gradient and AWOS accuracy/placement.
 
I have an RV3 and I typically am at 85mph in final for wheel landings. By the time I touch down I’m at 70-75 mph. And like you mentioned, make sure you are thinking of brakes on the downwind side in case the wind wants to weathervane you and get the tail down before you lose rudder effectiveness
 
MY POH numbers

I am in phase one flight testing with my RV-4. I was faced with a 13 mph crosswind component today and found that I had to use all my rudder and some braking to keep it on the runway. Is this normal for a RV-4? I plan to re-check my rudder travel but I am asking if there is any thing else I should be doing?
I had full flaps and approach speed of 75 mph. Should I approach faster and with less flaps to sustain more airflow?
Any other suggestions?
Thanks in advance
BTW...I love my RV-4....
Jon

Jon,
When I demonstrated my max crosswind component it was 18 kts. I vowed then to set my personal max below that. No "magic pilot stuff" was required to safely land, but had my hands (and feet) busy.
OSH 2022 has 26 g-34 x-wind, and it ripped off my rudder chains.
Proof that a Max exists for a reason.
Hope that helps.
Daddyman
 
My experience with the -6 is that 15 knots direct is pretty much it for me. That's with the wing way down and lots of opposite rudder, maintaining those inputs all the way to walking speed. I'd say 13 knots and 15 knots are pretty much the same number, with the difference being a rounding error between wind gradient and AWOS accuracy/placement.

Same here for my RV-6 and I suspect the RV-4 would have similar numbers since they use the same rudder.

Now.....waiting for the posts about routinely landing in 42kt crosswinds....seems to happen every time this topic comes up. :D
 
I landed my 6A one day in IA and it was 25G32 and probably 70* off the runway. I had plenty of rudder to manage the landing and can't remember if the pedal was to the floor or not. Can't speak to issues of managing the wind once the wheels hit in a tail dragger though. I am sure that is a whole different kettle of fish. I have the larger 8 rudder, so that makes it a bit less comparable. That said, I usually can't use full rudder in a slip, as it is more powerfull than the wing's turning force and will over correct.

Larry
 
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I won’t cite specific crosswind numbers, as it is almost impossible to know what the wind conditions actually are at your moment of touchdown….but as to the OP’s question on flaps, yes - if crosswind is reported to be at values that are making me nervous, I use less (or no) flaps for final approach and landing in all three of our TD RV’s. Just feels more solid that way.

Paul
 
I won’t cite specific crosswind numbers, as it is almost impossible to know what the wind conditions actually are at your moment of touchdown….but as to the OP’s question on flaps, yes - if crosswind is reported to be at values that are making me nervous, I use less (or no) flaps for final approach and landing in all three of our TD RV’s. Just feels more solid that way.

Paul’s no flap landing approach is also what I use here in Oklahoma when the winds are 20+ gusting to 30+. Spring and late fall in Oklahoma always provides more days with strong crosswinds than not. If we limited ourselves to less than 15 knot crosswinds there wouldn’t be many days to fly during the spring and fall.
 
I am in phase one flight testing with my RV-4. I was faced with a 13 mph crosswind component today and found that I had to use all my rudder and some braking to keep it on the runway. Is this normal for a RV-4? I plan to re-check my rudder travel but I am asking if there is any thing else I should be doing?
I had full flaps and approach speed of 75 mph. Should I approach faster and with less flaps to sustain more airflow?
Any other suggestions?
Thanks in advance
BTW...I love my RV-4....
Jon
For me & my RV4,,

Crosswind component greater than 15KTS, I won't even try.
10-15KTS, I will attempt, determining factor if I continue/abort is if I run out of rudder on final
 
That said, I usually can't use full rudder in a slip, as it is more powerfull than the wing's turning force and will over correct.
Larry

I find this hard to believe. Perhaps you meant ‘using full rudder in a slip requires a bank angle that I feel uncomfortable with’.
 
I find this hard to believe. Perhaps you meant ‘using full rudder in a slip requires a bank angle that I feel uncomfortable with’.

You are probably correct. I guess I have an internal brain limit on how far I am willing to bank the plane over on short final where I do most of the aggressive slipping, though I tend not to be afraid of aggressive banking in the pattern. That said, when I have full rudder applied, I have been unable to stop the turning tendency with aileron and need to back off the rudder. Maybe some day I will try this at altitude to prove you right or wrong, though I suspect you are right.

Larry
 
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In my RV-4, landing with full flaps and the tail on the ground, a crosswind once blew me maybe 10 feet laterally because the wing was still generating too much lift with full flaps. Don't know if this phenomenon was considered in other opinions offered.

And in my RV-8, I observed that flaps down could reduce rudder effectiveness.

Others with more experience may have better observations.
 
Thanks

I am in phase one flight testing with my RV-4. I was faced with a 13 mph crosswind component today and found that I had to use all my rudder and some braking to keep it on the runway. Is this normal for a RV-4? I plan to re-check my rudder travel but I am asking if there is any thing else I should be doing?
I had full flaps and approach speed of 75 mph. Should I approach faster and with less flaps to sustain more airflow?
Any other suggestions?
Thanks in advance
BTW...I love my RV-4....
Jon

Thanks for all of the good information and advice. I feel better now.
I will do the following:
1) Re-measure rudder travel with someone in the cockpit actuating the pedals.
2) Practice no-flap crosswind landings.
 
yup to all replies, keep your speed up, flaps or half flaps, (you can practice with this some time)
Also consider cheating a bit if you have a wide long runway, bye landing on the far side and using the extra width as you fly more into the wind.
 
Remember that during a cross wind landing the main reason we apply aileron into the wind is to augment rudder authority by introducing adverse yaw. The up aileron with it’s leverage out on the wing “virtually” makes your rudder bigger. And as you slow down applying more and more in-wind aileron adds more beneficial adverse yaw. Thank you adverse yaw.

An secondary benefit to keeping the upwind wing down is to limit the effects of a sudden gust from picking up the wing. With high-wing aircraft being more affected. This is the most common reason given for cross controls with upwind wing down during cross-wind landings given to new pilots during training. Probably because it avoids the whole dissertation on adverse yaw. And I further suspect the majority of flight instructors have never had the adverse yaw benefit explained to them or thought of it. And it really doesn’t matter because it isn’t so much as to “why” as it is to “how”.
 
Remember that during a cross wind landing the main reason we apply aileron into the wind is to augment rudder authority by introducing adverse yaw. The up aileron with it’s leverage out on the wing “virtually” makes your rudder bigger. And as you slow down applying more and more in-wind aileron adds more beneficial adverse yaw. Thank you adverse yaw.

An secondary benefit to keeping the upwind wing down is to limit the effects of a sudden gust from picking up the wing. With high-wing aircraft being more affected. This is the most common reason given for cross controls with upwind wing down during cross-wind landings given to new pilots during training. Probably because it avoids the whole dissertation on adverse yaw. And I further suspect the majority of flight instructors have never had the adverse yaw benefit explained to them or thought of it. And it really doesn’t matter because it isn’t so much as to “why” as it is to “how”.

I was always taught that the down aileron creates more drag than the up aileron, and on takeoff or landing has the effect of pulling that wing backwards - the adverse yaw that can be beneficial in a crosswind. With a left crosswind and using left aileron input, the right aileron is down and basically dragging that right wing backwards (in affect), which should help your right rudder effectiveness. However, on our RV’s the adverse yaw created by aileron deflection is lessened because we have Frise ailerons. The leading edge of the up aileron extends below the wing on the bottom, creating some drag in an attempt to equalize differential aileron drag. It makes it nice for flying because you don’t need much, or any, rudder when making standard rate turns in flight. It doesn’t offer much help in a crosswind though, other than holding the upwind wing down in gusty conditions.

Other airplanes with normal hinged ailerons exhibit much greater differential aileron drag. About a lifetime ago I flew DC-3’s and this type of adverse yaw was easily demonstrated. With it’s long wing and huge ailerons the effect was amazing. When we had a new pilot we would demonstrate what we called “steering toward the crash”. With a crosswind component of no more than 7 knots, we would takeoff with feet flat on the floor. Of course the DC-3 has a lockable tailwheel, but on the -3 the tail would come up very early in the takeoff roll, so it didn’t pin your direction for very long. With a small crosswind component the nose of the airplane would start to point into the wind early in the takeoff roll. That’s when we would “steer toward the crash”, like in a car. Roll the yoke in the direction the nose was starting to point. The nose would stop deviating and as speed built up, it would start going the other way. You could literally steer the airplane back to the centerline and stay there with nothing but aileron drag control - feet still flat on the floor. Of course you had to make sure engine power was even and not too much crosswind, but it taught a new tailwheel pilot a lot about the importance of proper flight control input.
 
Remember that during a cross wind landing the main reason we apply aileron into the wind is to augment rudder authority by introducing adverse yaw. The up aileron with it’s leverage out on the wing “virtually” makes your rudder bigger. And as you slow down applying more and more in-wind aileron adds more beneficial adverse yaw. Thank you adverse yaw.

An secondary benefit to keeping the upwind wing down is to limit the effects of a sudden gust from picking up the wing. With high-wing aircraft being more affected. This is the most common reason given for cross controls with upwind wing down during cross-wind landings given to new pilots during training. Probably because it avoids the whole dissertation on adverse yaw. And I further suspect the majority of flight instructors have never had the adverse yaw benefit explained to them or thought of it. And it really doesn’t matter because it isn’t so much as to “why” as it is to “how”.

Neither of the two reasons you mention for keeping the wing down in x-wind are it at all. Some airplanes (like RVs) have nearly no adverse yaw. And gusts and turbulence can pick up either wing.

You keep the wing down in x-wind purely to counter the turn that would otherwise develop by using the rudder to align the airplane with the runway.
 
Neither of the two reasons you mention for keeping the wing down in x-wind are it at all. Some airplanes (like RVs) have nearly no adverse yaw. And gusts and turbulence can pick up either wing.

You keep the wing down in x-wind purely to counter the turn that would otherwise develop by using the rudder to align the airplane with the runway.

+1. More specifically, if you don't bank the wind will simply blow you sideways. The sideways force due to the wind is much larger than the sideways force from the rudder (the rotational torques are in balance).
 
For me & my RV4,,

Crosswind component greater than 15KTS, I won't even try.
10-15KTS, I will attempt, determining factor if I continue/abort is if I run out of rudder on final

I remember that from training.

What I have found with my RV4 is that I'm able to maintain alignment on final with 25+- knots 40 to 60 deg off the runway but I was maxed out on rudder.

Even able to stay lined up until I lowered the tail and at that point when I suddenly weather vaned 40 degs into the wind and skidding down the runway and off into the field. I honestly thought that I was going to drag my wing tip. Luckily no damage except to my pride.

What I found is that with full rudder my tail wheel will unlock and stay that way until I'm able to kick it straight. Of course when your on the ragged edge that wont happen. Then when the tail comes down the tail wheel is in a free castering mode until until you can kick it straight and lock it again.

For me my max limit in this plane is a 15 kt crosswind.

Like anything its the sudden gusts that will get you. Then mix in high density air strip altitudes, mountainous terrain and of course shorter and narrower strips all add up especially when deciding to go with a flap or no flap landing and burning off a few extra knots for the gust factor etc.

Tim
 
My spiciest landing x-wind

I had full flaps and approach speed of 75 mph. Should I approach faster and with less flaps to sustain more airflow?
Any other suggestions?
Thanks in advance
BTW...I love my RV-4....
Jon

After over 800hr in my -4 and countless x-wind landings over the years, I finally had my spiciest crosswind landing last week. I took off with a strong headwind at 4pm runway 33R at MWC winds were 290 17-26. Didn't think anything of it. Met a friend for an hour or so nearby and returned after dark around 6pm. There has been construction around the MWC airport with regular NOTAMS for ground ops and closed taxiways. Did I listen to the NOTAMS? yes. Did I fully comprehend the NOTAMS that day?... the answer was no. Returning to MWC, the winds had picked up. I was confused as the controller vectored me for runway 22R. I did listen to the ATIS and noted that 33R was now closed due to it now being dark and the runway lights and PAPIs for 15L/33R out of service. I flew the 1mi final to 22R in a 40 deg crab angle looking at the runway in the gap between my left wing and the left side of the cowl. I knew I would have to work for it. Long story short, I got it down and snapped the screenshot of foreflight attached while taxiing. Full left rudder and a significant amount of left brake was applied. The airplane did start to yaw right around 30kts and had I not grabbed more left brake, it certainly would have ground looped (something I never thought possible in an RV-4). I decided that in the future, anything over 20kts direct would be worth considering diverting elsewhere. Not worth the bent metal.

As for your comment on higher speed on the approach, I wouldn't recommend the higher speed in steady x-wind being that it would only lengthen your flare. Typically you would increase approach speed by half of the gust factor but that is more so when landing into a headwind. As always, the trickiest moments are when the tail is no longer flying and its weathervaining around 25-35kts.
 

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Tim,
Your tail wheel should NOT unlock at full rudder deflection.
I recommend some adjustment to your TW linkage.
IIRC there is an informative thread (or a few) ref Rocket Links causing some wild rides because they would unlock the TW on one side with relatively small rudder inputs.
FWIW, I’m in the camp of sloppy loose TW chain adjustment. When I’m near full rudder deflection I don’t want the added input of full tailwheel deflection to suddenly kick in as the tailwheel contacts the runway.
I know many like a responsive tailwheel position married to their rudder, but it’s worth flying ones plane in both ranges of adjustment to see what really works for you.

R/
Dan
 
One thing I consider when it comes to personal X-wind limitations believe it or not is OAT. When it is really hot out, my limit increases vs when flying in winter. Simply because 15kts at -5C has much more power than 15 kts at +35C due to the air density. I really do notice the difference.
 
I don’t think this is correct since surface winds are not not reported as a true airspeed.
Ie.: tower and AWOS anemometer and surface windsock indications are not corrected for temperature.
 
I don’t think this is correct since surface winds are not not reported as a true airspeed.
Ie.: tower and AWOS anemometer and surface windsock indications are not corrected for temperature.

Huh? An anemometer is designed to measure the actual speed of the air going by, regardless of density or temperature. If this is not ‘true airspeed’ what is?
 
FORCE = Mass X Acceleration
The cups on the anemometer do NOT spin based on the SPEED of the air molecules but rather by the FORCE those molecules are imparting.
An indicated 15 KTS windspeed at temps of -5C and +35C are showing the same FORCE though the molecules of air are moving faster at the higher temp due to the lower mass of the air.
I don't believe the AWOS anemometer generated windspeed is corrected for temperature. If so, it cannot be a TRUE windspeed. It is an INDICATED windspeed.
 
FORCE = Mass X Acceleration
The cups on the anemometer do NOT spin based on the SPEED of the air molecules but rather by the FORCE those molecules are imparting.
An indicated 15 KTS windspeed at temps of -5C and +35C are showing the same FORCE though the molecules of air are moving faster at the higher temp due to the lower mass of the air.
I don't believe the AWOS anemometer generated windspeed is corrected for temperature. If so, it cannot be a TRUE windspeed. It is an INDICATED windspeed.

There’s no need to ‘shout’. -:)
Anemometers are carefully designed so that, after they reach equilibrium with the wind, there is no net force. On the with the wind side, there is a force equal to some coefficient times the air density times the wind speed minus the cup speed. On the opposite side there is a equal but opposite force, from a different coefficient (due to the back side being shaped differently than the front side) times the air density times the wind speed plus the cup speed. These numbers have to be averaged over the 180 deg of rotation. Notice that the air density appears the same on both sides, so it cancels out. There is a small complication if there is significant turning resistance in the bearing. But, basically, the rotation speed is proportional to the true airspeed. As it should be. Since the data goes to the NWS, can you imagine trying to explain to the general public how ‘windspeed’ is not really the speed of the wind??!
 
Apoligies

Apologies, Bob; no shouting intended. I should have used quotation marks vice caps. I hope my comments are always taken as a polite "discussion."
Apologies also to those following this thread for the Bob and Dan hijack...

My original comment on crosswinds in this tread came as a response to Pete:

because 15kts at -5C has much more power than 15 kts at +35C due to the air density.

My experience tells me that a reported 15kt wind at a cold temperature has the same relative effect on an aircraft as a 15kt wind at a hot temperature. Or at lower or higher field elevations.
As I said before, I believe "15 knots" is a reported relative force. The actual speed of the molecules imparting that force is different at different air densities, but the effective force is the same.

A clearer original response to Pete would have been: I don't use OAT to determine my personal crosswind limits on any given flight. I don't believe a reported 15 kt wind has "much more power" in the winter. If I'm wrong and it does, then my rudder has correspondingly greater authority so its moot.

R/
Dan
 
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I don’t think this is correct since surface winds are not not reported as a true airspeed.
Ie.: tower and AWOS anemometer and surface windsock indications are not corrected for temperature.

Nothing to do with reporting wind as a true airspeed. Sailors will understand what I am getting at. The pressure of the wind when it's very cold is more than when it's very hot. If it's moving at the same speed, cold air will exert more pressure against a given surface than warm air. In winter a 10 knot X wind will have more pressure against your tail than in summer.
 
Nothing to do with reporting wind as a true airspeed. Sailors will understand what I am getting at. The pressure of the wind when it's very cold is more than when it's very hot. If it's moving at the same speed, cold air will exert more pressure against a given surface than warm air. In winter a 10 knot X wind will have more pressure against your tail than in summer.

The sail, your plane and the wind speed instrument are all reacting to the same force. Sure, cold air will will make the wind relatively more powerful when hitting an object and forcing it to move, due to being denser and have more effect on your sail boat but it has the same affect on the instrument, so it is all relative. NOt a physicst, but am guessing that the wind instrument is more like IAS than TAS, but it doesn't really matter as it is reporting on the ultimate force of the moving air and that is all that matters, Just like TAS is not relevant for determining stall speed. The wing and the airspeed instrument are both reacting to density changes the same way, therefore no need for compensation. The IAS reading may not be accurate, but it shouldn't be in this case, as it would be useless if it was, unless you are REALLY good at doing math in your head.

If the NWS was temp compensating the wind speed, you would have to be doing a lot more math to figure out what actual force you will be fighting on landing. As long as the data is force based, the number is relative and therefore beneficial to you. Same way that you want your IAS to be un-compensated when trying to determine when your wing will stall. There is a time and place for both relative indications and true indications. Pilots should be more interested in the relative force applied to their planes than the true numbers that separates speed from density.
 
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Excellent posts here. The concept of IAS being a perfect pilot reference has been brought home when sea-level flatlander pilots fly up to the high country and can't get over how strange it feels to be in the landing pattern with higher ground speeds despite having the same IAS. In fact there have been a handful of pattern stall-spin accidents when the unaccustomed pilot gets distracted by the ground speed and subconsciously slows down so things look right out the window based on their visual cue experience instead of trusting IAS.
 
The sail, your plane and the wind speed instrument are all reacting to the same force. Sure, cold air will will make the wind relatively more powerful when hitting an object and forcing it to move, due to being denser and have more effect on your sail boat but it has the same affect on the instrument, so it is all relative. NOt a physicst, but am guessing that the wind instrument is more like IAS than TAS, but it doesn't really matter as it is reporting on the ultimate force of the moving air and that is all that matters, Just like TAS is not relevant for determining stall speed. The wing and the airspeed instrument are both reacting to density changes the same way, therefore no need for compensation. The IAS reading may not be accurate, but it shouldn't be in this case, as it would be useless if it was, unless you are REALLY good at doing math in your head.

If the NWS was temp compensating the wind speed, you would have to be doing a lot more math to figure out what actual force you will be fighting on landing. As long as the data is force based, the number is relative and therefore beneficial to you. Same way that you want your IAS to be un-compensated when trying to determine when your wing will stall. There is a time and place for both relative indications and true indications. Pilots should be more interested in the relative force applied to their planes than the true numbers that separates speed from density.

Waay too complicated. The main difference is that the anemometer has no resistance to the wind, regardless of temp. I can say from experience however that a 15 knot crosswind in the Caribbean is very different from a 15kt crosswind in the Arctic.
 
Simple

These discussions are interesting, however, the only thing that really matters is that you fly the airplane…

I often chuckle at work when the same guy asked for a wind check five times on final and the controller finally answers “…it’s blowing…”
 
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