Re: [goking] Mountain profiles for Ws
I keep looking though old posts and comments concerning yuris calculations to show a way forward
to accomplish exits away from non vertical slopes. There seems to be an agreement that a 45 degree AoA during the first few seconds
will give max distance away from the vertical. This gives maximum side force. moving you away from the wall while keeping drag
higher ,meaning you fall slower giving more time as you fall,to move away. The actual pitch angle would be about 10 degrees more.nose up
the first couple seconds. 35 degree WS nose down pitch angle would equal 45 degree AoA assuming 80 degree flight path for first 3 seconds.
There have been a few comments to say that alot of WS flights move away faster from exits than yuris calculations show. Is this
due to accelerated push offs , upslope /lift winds , light Wsuiters with larger ghost type wings? Theory says 200ft out
400ft down 60 degree achieved average angle . That seems about right. Also seems you could be at about 4 sec220 ft down and have established
a 60 degree flight angle. The actual angle of the cliff at this point is < 80 degrees to clear. with a 5mph pushoff.
As you get to this approximate 4second fall, 220ft down ,70mph glide speed,60 degree angle, if you maintained the same pitch angle your
AoA would now be 25 degrees. This puts your wing in the fully stalled region , but not at the 45 degree desired optimun.
So your WS is not producing as much lift and about the same drag.. So,as I am dealing here with averages, It would seem to be better to launch
at 10 more nose up to start. Also In the 6 second fall area your approaching bestglide speed which which would be approximate 10 degree nose
down pitch giving 10 degree AoA. So then there would be only about 15 degrees of pitch angle. change as you went from the 4-6 to say 8
second range. The.Problem is the transition from this 45AoA theory optimun through the 20/30AoA degree critical stall region as you go nose up.
Also in the couple seconds you go through this transition you loose lift. Possiblly the transition is quick enough along with dynamic effects that these
problems wouldnt occur. but it is at a critical point.
Most of my experience suggests that it could be best to start at 45 but be stabilised 55 degree nose down by the time you reach 3-4 second fall.,
so that your AoA would be <15 degrees giving max lift but out of the stall area .This gives a more stable platform even though you have to go
through a few more seconds of pitching up to get to your cruise speed.
I am sure I didnt see all of yuris posts. But one thing about his graph which compared 45degree AoA distance to best L/D AoA distance
for the launch cycle, is that he should have used best sink AoA. This gives equal lift to the 45 AoA launch. You biuld up speed faster which
is not so good for the fall distance but your wing is operating in a more stable position. If you launch to hit a 55 degree nose down pitch at
3 seconds and 130ft+ down , you can then start a nose pitch up of about 5 degrees per second and you avoid this transition through the
critical stall area. , at a critical point of flight.
