Crosswind 90 degrees. Which Way?
Join Date: May 2002
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I did enjoy, after the front appeared, on Saturday with a certain Piper single attempting to land.
Avalon tower: "VH-ABC be advised that the crosswind on Runway 18 is now 36 knots".
VH-ABC: "HALLELUJAH!"
Points for having a go but there was no way. Back from whence he came.
Avalon tower: "VH-ABC be advised that the crosswind on Runway 18 is now 36 knots".
VH-ABC: "HALLELUJAH!"
Points for having a go but there was no way. Back from whence he came.
I can tell you that with exceptionally strong crosswinds and a forward C of G you can run out of elevator authority in the V-tails
Full fuel and Chuckles and I up front get nowhere near it - full fuel and 235kg in the front seats puts you on the forward limit!
Dr
Last edited by ForkTailedDrKiller; 16th Mar 2009 at 02:49.
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This came up for me yesterday when departing from Avalon East with some 15+ crosswind. In my particular aircraft I need a right crosswind versus a left and I was happy to see that 17 was in use. With a left crosswind I get issues with the torque of the engine combined with the left crosswind weather-cocking me into the wind particularly when I lift of the nose wheel early as per normal operating procedure.
If it is at or just after sunrise or just before sunset: with the sun behind you.
Torque and weathercock issues aside, I'm with Glekichi and his reasoning. The only other one I could think of would be if other traffic are already established in the circuit, you would use the same runway.
Torque and weathercock issues aside, I'm with Glekichi and his reasoning. The only other one I could think of would be if other traffic are already established in the circuit, you would use the same runway.
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I can't beleive what I am reading here!! Me thinks all of you have way too much time on your hands!!!
Clearly there is both an academic side as well as a "real world" scenario. Give the academic answer on the test and give the interviewer an answer that will save the company money!! It's that simple, don't complicate it!
Clearly there is both an academic side as well as a "real world" scenario. Give the academic answer on the test and give the interviewer an answer that will save the company money!! It's that simple, don't complicate it!
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I got it straight again - so I don't think I had "run out of rudder" - just a once in 30 yr brain fade!
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Thanks
Altimeters, Arnold E and a few others were right on to it. No trick to it. If you let the wind counter the P factor you will have more control authority especially so in something like an A36 Straight tail or FTDK's V tail. I was just interested to see what you all thought. Thanks for the replies.
Groggy
Groggy
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The original thread was about a 90 degree x/wind, quite frankly in that case you take off in whatevrer the hell is the most convenient direction to depart! Because there is no difference at all! if its 90 degrees to the runway! Simple really!
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Whichever way is easiest to join given your current heading (join midfield crosswind and save time rather than doing a 180 and coming from the "dead side".
Failing that just try to remember which tyre is in the worst shape and spread the wear and tear around between L and R. (OK this one is mostly a joke.)
FRQ CB
Failing that just try to remember which tyre is in the worst shape and spread the wear and tear around between L and R. (OK this one is mostly a joke.)
FRQ CB
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The comments regarding propeller torque are valid for the mustang or something similar, but should not be a problem on your light single like a C210. It has a certified crosswind limit (which you should not be exceeding unless you want to void your insurance policy), and that crosswind limit (as someone has said earlier) does not have direction limitations. The aircraft has been demonstrated as capable in that crosswind from either direction, so it can be done safely.
However....
If runway length & obstacles are a consideration, have a good think about the wind direction at a few hundred feet.
This is because the wind direction just a few hundred feet above the ground can be quite different to the pure crosswind you have on the ground. The change in direction and increase in strength of the wind with altitude is known as wind gradient.
If it was a nice long runway, I'd take either. If it was a marginal length runway, I'd have a look at the area forecast wind direction at 2000', and make sure I was taking off into wind.
And if I was landing on same marginal runway with pure crosswind, I'd fly a couple of crosswind legs over the top of the runway first and find which way I'm holding drift. This allows you to work out which way the wind is above the ground, and avoid tailwinds on final or increasing tailwind with altitude during a missed approach.
However....
If runway length & obstacles are a consideration, have a good think about the wind direction at a few hundred feet.
This is because the wind direction just a few hundred feet above the ground can be quite different to the pure crosswind you have on the ground. The change in direction and increase in strength of the wind with altitude is known as wind gradient.
If it was a nice long runway, I'd take either. If it was a marginal length runway, I'd have a look at the area forecast wind direction at 2000', and make sure I was taking off into wind.
And if I was landing on same marginal runway with pure crosswind, I'd fly a couple of crosswind legs over the top of the runway first and find which way I'm holding drift. This allows you to work out which way the wind is above the ground, and avoid tailwinds on final or increasing tailwind with altitude during a missed approach.
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In an American built aeroplane (ie the propellor spins clockwise from the cockpit), the torque effect will need right rudder to keep the nose straight down the runway. A crosswind from the right helps to nullify this effect, a crosswind from the left exaggerates it. That said, the only aircraft I have flown that has even come close to being a concern is an Airtractor 802. (I have not flown a high performance warbird.) They can nearly run out of rudder on takeoff in a strong left crosswind, however they are fitted with rudder trim. It is generally only when you forget to set the trim before takeoff that you start to worry. Therefore, I would surmise that the direction of crosswind should be of little concern to any reasonably skilled pilot unless:
a) You are flying a tailwheel aircraft and,
b)it has a lot of horsepower.
a) You are flying a tailwheel aircraft and,
b)it has a lot of horsepower.
If you are flying a taildragger which has no differential braking system, then even if it's low horsepower, it can bite. Therefore if everything else is equal, put the crosswind on the favourable side to counteract any torque or gyroscopic effect. Other trick when it's right on the limit is to take off at a slight angle across the runway (if it's wide enough) to reduce some of the crosswind component.
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Mach E
I'm not so sure that that technique actually helps a lot.
eg. assume somewhere like YSSY with a 45m runway width and (say) you need 500m to get airborne, if you start at the far edge of that runway and reach the other edge when airborne then the angle offset is about 5 degrees, which will decrease the 90 degree crosswind component by about 0.4%.
With a 'normal' GA airstrip, the width is usually 30m and the angle offset becomes about 3.4 degrees and a 0.18% xwind component improvement.
Now as for an 18m wide strip......
Other trick when it's right on the limit is to take off at a slight angle across the runway (if it's wide enough) to reduce some of the crosswind component.
eg. assume somewhere like YSSY with a 45m runway width and (say) you need 500m to get airborne, if you start at the far edge of that runway and reach the other edge when airborne then the angle offset is about 5 degrees, which will decrease the 90 degree crosswind component by about 0.4%.
With a 'normal' GA airstrip, the width is usually 30m and the angle offset becomes about 3.4 degrees and a 0.18% xwind component improvement.
Now as for an 18m wide strip......
Last edited by Biggles_in_Oz; 17th Mar 2009 at 11:08. Reason: yeah we're supposed to be able to cope with max demonstrated xwind., but......
Oh good oh. I'm presented with this dilemma daily when taking the old P-51 out for a gallop
PS. Come for a buzz in my Seafury one day. That'll screw you six ways left of sunday!
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Some of my considerations for runway selection with 90 degrees of X-Wind
HD
- Sun direction and elevation
- Winds aloft
- Terrain on departure
- Houses/buildings/populous areas
- Circuit direction, First turn into wind may help
- Established traffic pattern
- Preferred circuit direction – ERSA
- Torque/P effect etc
- Runway slope
- Airspace proximity
- terrain/structures on windward side that could generate shear/turbulence
- If Ag strip, where is the loader?, land toward depart away from
- Direction of departure/arrival
- Which end are you parked on/vacating to
- Where is the Bowser/Hangar
- If runway 13/31 , avoid 13, this could mean bad luck
- If wind is too strong, where is nearest pub?
HD
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given engine torque, P- factor and slipstream on a single engine aircraft, I would try to take-off using the rwy with crosswind counter-acting these effects...even slightly....but there's lots more to take in consideration...I would say rwy slope & obstacles are main issues...
