Crosswind Takeoffs

[Sexual Chocolate]

SOP for a X-wind landing: crab into wind, straighten with rudder before flare, into-wind wing down with initial touchdown on the appropriate main wheel.

Say you're operating on the X-wind limit, in fairly gusty conditions, from a strip cut out of the trees and with alot of mechanical turbulence.

Used to have a job on a 182 with a dodgy nosewheel that would develop a serious shimmy if you held the nosewheel on when approaching rotation speed, and spent alot of time operating out of strips like the one described above. I know, I know - shimmy is a defect shd be entered in the MR etc etc. That aside...

Directional control being a priority, I started using a technique where i'd leave the pressure off the nosewheel, aileron into wind etc, and as the wing started to energise i'd use much the same procedure as you do for landing and drop the into wind wing while poling over a little and keeping the into-wind wheel on the deck - allowed me to build up a little more speed, get a better margin over the stall which seemed like a good idea given the gusty conditions. Then rotate as normal.

With practice I found it worked really well in strong crosswinds, felt smoother and more controlled than holding all three wheels down, gave better directional control and gave me more protection from the Mech. turbulence.

Question is: I did this recently with a new employer who freaked out and claimed I was going to bury a wingtip. Thinking it through, I can't see the difference between dropping a wing when landing and dropping a wing on takeoff. What do PPRuNerz think?

[swh]

Your new employer might have saved your life.

Always want a positive rotation in such conditions, best angle, above tree height lower the nose to normal climb.

Delay the takeoff if windshear exists.

[VH-ABC]

So you developed this technique due to a problem with your 182's dodgy nosewheel.......?

Maybe you could have gotten that prob fixed, then moved onto the test pilot stuff my friend.

[Captain Sand Dune]

Should work really well if you've got a flat main as well...:} :} :rolleyes: :rolleyes:

pure gold!!!

[Sexual Chocolate]

First of all, i'd like to thank VH-ABC for repeating what I myself acknowledged in my original post. Clearly, after careful consideration and realising that you knew nothing of the commercial, personal or career circumstances under which I chose to continue operating this aircraft rather than MR-ing the nosewheel, you felt that you were the most suitable person to pass judgement on my decision.

Secondly, i'd like to thank swh and request a little clarification. Positive rotation, sure - allways a good idea. Why best angle? If the strip's a short one then yes on that too. But if the intention is to clear the messy air ASAP I would have thought you want minimal time below the tree line which means fastest possible climb which means best rate yeah? Delay the takeoff if windshear exists - do you mean until the windshear goes away or until you have higher speed in the T/O roll?

Finally, I intentionally spelt out the logic behind my thinking in the hopes that someone or manyone could point out the flaws in my thinking and rather than giving me a do this do that response, help me to understand the incorrect principles behind my apparently suicidal tendancies.

[Oktas8]

Finally, I intentionally spelt out the logic behind my thinking in the hopes that someone or manyone could point out the flaws in my thinking and rather than giving me a do this do that response, help me to understand the incorrect principles behind my apparently suicidal tendancies.
You seem to be more experienced than I am in your kind of operation (strip work etc), but I'm so pleased to find someone who wants to know why rather than just what that I'd like to help if I can!

Regarding why a technique might be deemed safe for landing but not for take-off - perhaps it might be helpful to look at the likely effects of unexpected changes in airspeed.

On landing in turbulence, if we suffer a sudden loss of airspeed, the aircraft lands a little early. No big deal I think. If we suffer a sudden increase in airspeed, we float a little further, which might be a small problem (centreline control being more difficult), but at least we will certainly be landing in the near future, for which we are configured and have the appropriate speed.

On taking off though, turbulence might put us into the air at too low a speed to be safe. In this case a sudden loss of airspeed is very bad: I can picture the aircraft developing significant drift immediately before touching down again on the main wheels, which will cause a swing out of wind (into wind if taildragger). The aircraft is now drifting to the downwind side of the runway, and not aligned with centreline either. At high speed the pilot's correction is likely to induce yawing oscillation.

It seems to me that the old rule to "hold the aircraft on the ground and rotate at a higher than normal speed" is designed to stop the aircraft getting airborne and then touching down again with drift. Your technique does seem to carry a strong risk of this happening, unless there is no chance at all of windshear.

Hope this makes sense...
O8

[DeRated]

Wing down, A/c aligned with the strip (flapless preferably), nosewheel just out of the dirt... and the 182 will fly off when ready (at a higher airspeed than dragging it off too early).

Reducing the slip angle as the speed builds up, even if the aircraft comes back to the ground, it is still aligned and accelerating.

So no requirement to climb immediately at a low airspeed in turbulent conditions.

Then, when the airspeed (and ground clearance) is sufficient, reducing the rudder pressure allows the aircraft to roll/yaw into the wind, ailerons to wings level and continue climbing away.

Overall, a very smooth procedure.........

The basic requirements are:

Know your aircraft handling.....

Be good at x-wind landings/take-offs......

The more practice, the better you get, the smoother your flying becomes, the less nervous your pax are......:p

Some pilots don't try (or learn) anything different from what they were taught during basic training. (and that was from an instructor teaching what they had learnt in basic training........!) :confused:

Not a great idea in low wing a/c.... because most don't have the roll/yaw control of Cessnas - or the wingtip clearance at max Xwind.

Hot Choccy - you can only get better by trying......

(Loved the 182 in the Qld bush - lot of fun)

[Sexual Chocolate]

Oktas8 & DeRated - thanks for your replies guys. Good to get some food for thought and constructive perspectives. Cheers!

[4SPOOLED]

i always though you just closed your eyes gripped the stick tight, counted to 3, hit the throttle let her rip, rounded up a tad over normal take of speed, wiped the sweat from your forehead then started thinking about landing...

On a seriouse note, i put full ailerons into wind, apply power, as IAS increases slowly roll the ailerons back to a centred position at the exact point i intend to round up...I always use a stab of back stick just to stop any unwanted shimmey in the nose wheel and to minimise rolling friction for better performance. I wouldnt want the wing in a drop because one wing would would leave ground effect a tad before the other causing unwanted roll or yaw, at least with the A/C flat you can point the nose into the wind and fly as per normal as soon as your off the ground.