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  #21  
Old 11-13-2022, 01:03 PM
riobison riobison is offline
 
Join Date: Jul 2011
Location: Oliver BC & Red Deer Alberta Canada
Posts: 473
Default

Quote:
Originally Posted by N184DA View Post
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
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  #22  
Old 11-18-2022, 01:24 PM
Nived17's Avatar
Nived17 Nived17 is offline
 
Join Date: Aug 2016
Location: Milwaukee, WI
Posts: 54
Default My spiciest landing x-wind

Quote:
Originally Posted by Sully73 View Post
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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  #23  
Old 11-18-2022, 07:19 PM
andoman andoman is offline
 
Join Date: Jul 2006
Location: Payson, AZ
Posts: 122
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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
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  #24  
Old 12-01-2022, 08:19 AM
Pete O Static Pete O Static is offline
 
Join Date: Sep 2021
Location: Lac Brome, Quebec Canada.
Posts: 18
Default

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.
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  #25  
Old 12-02-2022, 12:26 PM
andoman andoman is offline
 
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Location: Payson, AZ
Posts: 122
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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.
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-HRII project: paint and panel to go!
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  #26  
Old 12-02-2022, 07:46 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 8,684
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Quote:
Originally Posted by andoman View Post
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?
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  #27  
Old 12-02-2022, 09:37 PM
andoman andoman is offline
 
Join Date: Jul 2006
Location: Payson, AZ
Posts: 122
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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.
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"The plane won't build itself..." RV-7A N7.62MM sold
-RV4 purchased. Extensive refurbishment complete. “Takes off by it’s self, flys hands off, lands by it’s self...”
-HRII project: paint and panel to go!
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  #28  
Old 12-03-2022, 01:48 AM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
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Quote:
Originally Posted by andoman View Post
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??!
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  #29  
Old 12-03-2022, 03:10 PM
andoman andoman is offline
 
Join Date: Jul 2006
Location: Payson, AZ
Posts: 122
Default 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:

Quote:
Originally Posted by Pete O Static View Post
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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"The plane won't build itself..." RV-7A N7.62MM sold
-RV4 purchased. Extensive refurbishment complete. “Takes off by it’s self, flys hands off, lands by it’s self...”
-HRII project: paint and panel to go!

Last edited by andoman : 12-03-2022 at 03:16 PM.
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  #30  
Old 12-31-2022, 04:45 PM
Pete O Static Pete O Static is offline
 
Join Date: Sep 2021
Location: Lac Brome, Quebec Canada.
Posts: 18
Default

Quote:
Originally Posted by andoman View Post
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.
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