Cat3 Autoland,
Thanks for the plug, but if my teaching was so good why did you look so puzzled?
. .Crosswind Limits.
Here are my answrers to the questions above.
1. b.. .Sweeping back the wings decreases aspect ratio. Decreasing aspect ratio decreases the gradient of the CL:Alpha curve. So for any given gust induced change in alpha, the CL change will be smaller for a swept wing than for a straight one. So increasing sweep back angle decreases gust load in any given gust.
. .2. b.. .The CL: alpha slope is a straight line up to the stall, so doubling the intensity of the upward gust would double the increase in CL. A gust causing a 1 degree increase in angle of attack increased CL by 0.15 from 0.55 to 0.7. A gust of twice this intensity would therefore increase CL by twice as much which is an increase of 0.3.
. .3. b.. .The CL : Alpha curve is a straight line up to the stalling angle, so within this range, if a 1 degree increase in alpha produces an increase of 0.06 in CL, then a 5 degree increase in alpha will produce an increase of ( 5 x 0.06 = 0.3) in CL.
Load factor = lift / weight and in straight and level flight this equals 1. So assuming the aircraft was in straight and level flight prior to the gust, its load factor would have been 1. Although the weight of the aircraft is not given, its load factor of 1 can be expressed as a ratio of CL to some figure representing weight, provided the ratio of the two is equal to 1. That is to say the load factor before the gust equals 1 which can be expressed as 0.44 / 0.44.
. .On this basis the load factor in the gust is equal to the new CL / 0.44 which is = (0.44 + 0.3) / 0.44.
The new load factor is therefore 0.74 / 0.44 which is 1.68.