Demonstrated Crosswind Capability?

Certificated airplanes all have a demonstrated crosswind capability, frequently 17 knots (20 mph), which means that the factory has demonstrated that the plane can be landed in that crosswind by an average pilot, to paraphrase the FARs rather heavily. (FAR 23.233(a) is part of the answer but I bet there's more than that).

We've all read stories of varying levels of credibility about how much crosswind an RV can handle, but are there any authoritative demonstrated crosswind capability numbers in line with FAR 23 for the various RV models? Please, DO NOT POST HOW MUCH CROSSWIND YOU'VE LANDED IN AND GOTTEN AWAY WITH. THAT'S NOT THE QUESTION.

Flew solo this morning for the first time after the most recent spinal surgery, after three flights with a CFI buddy in the RV-9A. According to the G3X (handy little critter!), winds (all out of the south) were 15 knots at 1,000 ft; 25 knots at 500 ft; 20 knots at 200 ft; and at the surface, sometimes as little as 6 knots, sometimes more. (I've not downloaded the data to get surface winds). The gusts meant that I couldn't get any reliable wind info on the 90 degree crosswind landings, and I don't know what average pilot technique is, and I had flaps 10 or 20 to get the nose down on final, so my numbers don't answer my own question.

Anybody got any *reliable* information?

23.233(b) The airplane must be satisfactorily controllable in power-off landings at normal landing speed, without using brakes or engine power to maintain a straight path until the speed has decreased to at least 50 percent of the speed at touchdown.

Interesting that a power off landing is required for 23.233. AC90-89B only references taxi testing in crosswind conditions. Sounds like a good experiment for a retired engineer to perform On thing that I have noticed about landing in gusty crosswinds in you're -9A is that it is easy to over control the airplane in pitch. Not that the airplane is "twitchy", but pitch seems more sensitive in the flair.

On another note, now that I am becoming marginally proficient with the G3X/GTN650, and the Almost a -14 seat mod is installed I am REALLY enjoying flying this beautiful machine. I think I am in love....don't tell my wife!

On the 7A what I find is the rudder is especially effective - you could probably do much better than the formula. On the other hand, it's a light airplane, and the trick won't so much be landing on the runway; instead, getting to the hangar.

So, I have found the formula to be a good yardstick.

Dan

32 kts direct crosswind is the limit for me and I don't want to do it again.

I skipped sideways for 72 feet of the 150' wide runway but I got it stopped and didn't groundloop. It did take all the rudder I had and the right wing almost touched.

The crosswind capability of these aircraft is amazing!

I was once given an runway 24 as the active when the winds were out of the north, gusting to 50 kts. I lined up, put in full control deflection and got blown sideways. I went around and landed on 36. That was a flight I will never forget!

should be "taxiing limit"

DanBaier said:

... On the other hand, it's a light airplane, and the trick won't so much be landing on the runway; instead, getting to the hangar...

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I'll second that. Flying an RV-4 out of Troutdale, OR in the winter months one routinely sees steady winds with 20 to 30KTS+ gusts but it's typically straight down the runway. The close in final landing phase can be a bit twitchy but doable. Everything else after that is very difficult... taxiing to the hangar, opening/closing the canopy, wrestling the plane in/out of the hangar.

t

Hi

You are wasting your time asking such a question I think. RV's are not certified aeroplanes and are not tested in the same way. Besides that what on earth is an average pilot?

All you are likely to get is I did this speed or that speed as has started to happen despite your request for it not to.

I flew my 9A for 5 years and it is very capable in crosswinds its limits were set by my ability and it could no doubt have exceeded them.

I am curious about what you mean about using flaps to get the nose down. 90% of the time I used full flap as I do in my 4. More drag slower touchdown speed and you actually want the nose up in the flare to land on the mains.

For what its worth I used 15knts as a go no go before take off.

Hi Ed,

I think I know just what you are looking for - an actual flight test matrix/build-up using Cooper-Harper ratings to determine at what crosswind you drop from Level 1 to Level 2 handling qualities. Unfortunately, I don't know of anyone that has taken the time to do the study. The problem, of course, is that you can build a test matrix, but you can never find all of the wind conditions that you need to finish it. If you want a 17 knot direct xwind, for instance, you'll just not get that unless you go chasing runways around the west in the windy months. I've alwasy thought the best way to do it is to pick a lakebed with a steady wind, and go vary landing heading relative to the wind. Fun to talk about, but I don't know anyone bored - I mean dedicated - enough to do it.

We're not alone of course. In my old job, we defined a crosswind test matrix for the Shuttle back in 1988. When we finished the last flight in 2011, we had collected some data points, but never filled the matrix. Best laid plans.....

owning the runway

Paul, you forgot to mention that in your old job.... you guys "owned" the biggest darn lake bed around.... that I have ever seen!
On the OP topic, I find in my 9A that pointing the nose down leads quickly to accelerating out of airspeed limits for full flaps. Perhaps that is why Ed has used less than full. And habit from Cessna days when CFI's always taught crosswind landings that way.

I didn't mention my flap settings I use for cross wind landings.

It is simple, I use all of them, regardless of the wind conditions.

Ed, we need to get together and go fly some.

Anecdotal evidence here, I've landed my short tail 6 in a 20kt gusty 90 degree direct crosswind with turbulence coming off the hangars immediately to the side of the main 13/31 paved runway at my home airport because our 04/22 turf x-wind runway was too muddy to attempt landing upon. Kept it on the pavement but needed all the rudder my plane had, and surely removed some excess rubber from the tires. Neither I nor my plane were particularly happy with it, but it was a "great" landing in that the plane was still usable afterwards
Now, I've set 15kts as my personal direct x-wind limit... any more than that is just unpleasant and risky.

not so much crosswind NUMBER, but GUST delta

so I am a low-time -9a pilot, don't fly frequently, not proficient at all.

....so for me, a full on 5 knot crosswind with gusts to 15 is too much!
the variation is what makes control difficult.
Now, I have little to no comparison except spam cans 25 years ago, but the wind sure likes to get under the 9's wing and make the final approach and flare, ummm, 'not stabilized', when it's gusty.
When I was young and had reflexes etc., I once flew a crappy flight skool Cherokee 140 in a pretty stiff 90 degree + - crosswind....maybe 20 kts.
I had no problem holding it in a full cross-control slip, nice stable approach, but I still drifted a bit across the 100' wide runway during the flare and touchdown. ( about 15 hrs under my belt)
After several unsatisfactory touch 'n goes, I parked it and went to talk to my instructor. We went up immediately, and he tried one......
'pardner, we are exceeding the crosswind capability of this aircraft! THAT's why you're having trouble."
I doubt I'll get to try that anytime soon in my current ride, but as many have said, personal limits and acceptable rubber on the runway trump the aircraft's limitations for most of us.

First, "demonstrated cross wind" is a certification requirement for normal aircraft. It's based on stall speed and is not considered limiting.
Second, most RVs have very good rudder authority. Touching down aligned with the runway with no side drift is usually not the problem. The problem arises, as several have posted already, at around 45-50 knots, when only friction keeps you from sliding sideways. Weight, tire tread, and runway surface are the key factors, which, of course, can vary. Which is why it is so hard to characterize.

flyboy1963 said:

... I once flew a crappy flight skool Cherokee 140 in a pretty stiff 90 degree + - crosswind....maybe 20 kts.
I had no problem holding it in a full cross-control slip, nice stable approach, but I still drifted a bit across the 100' wide runway...

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I owned a Cherokee 140 for about 10 years and put about 800 hours on it... the thing could make childs play out of crosswind landings better than any other plane I ever flew. I routinely flew it in crosswinds that I would never dare in my RV6.

I have landed in a crosswind strong enought to cause me to start sliding out of the pilots seat (belted) due to booting full left rudder HARD and significant right bank. But, since it is anecdotal and not part of a study, I'll keep the reported xwind to myself.

Neal@F14 said:

Anecdotal evidence here, I've landed my short tail 6 in a 20kt gusty 90 degree direct crosswind with turbulence coming off the hangars...

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Therein lies the problem with x-wind anecdotes - you never really know how much wind you're exposed to. The very fact that you were experiencing turbulence off the hangars indicates that the 20KT reported wind (from a 33' high anemometer) was already significantly cut, not only by the hangars, but because it will also diminish closer to the runway height.

BobTurner said:

First, "demonstrated cross wind" is a certification requirement for normal aircraft. It's based on stall speed and is not considered limiting.
.....

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The regulations base the demonstrated number as a minimum based on stall speed (0.2 x Vso)

However manufacturers can, and do, test to a higher number.

My Tiger POH list 16 kts as the demonstrated value, which is in excess of 1/5 of Vso.