Quote:
Originally Posted by AndyJWest
In the days when I used to fly radio-controlled gliders this effect was very noticable - probably because their airspeed was low compared to a full-sized aircraft. In a strong wind the safest way to land was to push the nose down as you came below about 10-15 ft, and then level off about a foot off the ground to bleed off speed. Trying to maintain a constant airspeed was asking for trouble as you could only do this by diving, which put you into slower air, so you had to dive some more. I should imagine real glider pilots have the same difficulties too.
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Exactly! And you have to consider it in all aircraft... Big airliners landing at small airfields in strong wind can be seen "losing control" and "fall" the last 10 meters and do a bounce that almost blows the tires. The computers can not calculate the wind gradient as it is dependent on the physical "layout" of the obstacles around the airfield. The proper way of doing it to add x km/h to your approach speed depending on the wind. The problem is if the wind gradient is a lot less present than estimated and the field is small... Then you will have to "battle" the ground effect trying to get you plane on the ground before you run out of airfield. On large air fields major obstacles are therefore cleared from around the runway (for other reasons too
), but some small air fields can have a forest slope on one side. When the wind comes from that direction it gets really bad - we have one field nearby that is like that, many good pilots have bounced both one and two times trying to land in cross wind there.
The problem with gliders is naturally that you cannot smack the throttle if you feel the air speed drop (you always feel it first!) - hopefully you are on full airbrakes and a steep final approach which is the recommended way in heavy wind (just like you did with your rc glider!). If the wind gradient is bad you can retract the airbrakes to get a similar effect like applying throttle. In our Bergfalke case with the 90 km/h wind we approached like a cross in the sky with full air brakes and maximum side slip to have maximized kinetic energy when the wind gradient "stole" the speed. It was still really nasty. The second problem with a glider is naturally if you have added to much speed to counter the wind gradient and the field is small - then your run out of field and you cannot go around for another try
Side slipping was used a lot in old planes with crappy air brakes / flaps. I always use it in IL2 too when landing to be able to do a steeper approach. Works great!
Edit: WWII fighters with minimum forward view used side slipping while landing to be able to see the runway too... Many had bad flaps/airbrakes and in some cases it was the only way. I have flown the Tiger Moth some times and that baby has to be slide slipped at fat angles on final approach as there are no flaps at all... Remember that crossed rudders are a "no no" if the speed is to low - so beware though
02-05-2010, 11:27 PM
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