View Single Post
  #20  
Old August 23rd 10, 10:10 PM posted to rec.aviation.soaring
mike
external usenet poster
 
Posts: 149
Default required LD versus required MC to make it home ??

On Aug 22, 8:10*pm, akiley wrote:
Hi All,

I'm aware of and use the math formula to get my rental Cirrus back to
home base, but I like to back it up with SeeYou mobile. *I know it's
recommended to use required LD to target making sure you have entered
a correct polar and safety altitude. *But this doesn't account for
winds does it? *If you are flying away from your target wondering how
far you can safely fly, you can't depend on required LD because big
headwinds can make this number useless. *As an example, I notice I've
got 25LD required to my home base. *I turn around and because of the
headwinds, I can only make 18LC. *Outlanding anyone.

I'm curious about MC required to target. *Wouldn't that be better to
use if you make sure all data is correct such as polar, winds, safety
altitude and make sure the correct target is activated. *This way, I
can wander away from my home field and I know if my MC doesn't fall
below about say 7 (which plays out to about 20 LD in no wind) I am
fairly assured of making it and that this MC will be wind aware. *Of
course it can't know about hitting lots of sink, but it seems a better
way for my type of non task, local soaring.

Before I finish, I would like to note that the MC to target NavBox in
SeeYouM doesn't always update very quickly if you change the winds
aloft manually. *For this problem, I scroll the MC value untill the
little glide slope type indicater on the left side of SeeYou centers,
then compare that MC to the required MC NavBox.

akiley


I look at "altitude required", with either an auto or manually set MC,
depending on the time of day. For a final glide, I climb to the
altitude I feel is appropriate for the glide home and then adjust my
speed, depending on the air mass I am gliding through.