Thanks for the reply and figures - yeah I can't seem to get hold of the flap figures anywhere! FCTM just gives the basic speeds and RoD.
Can anybody verify I'm doing the following correctly to calculate descent angle as its been ages since I last did trigonometry. At least this way I can just note the RoD in different flap configs over the next month or so and calculate the descent angles that I'm after.
Lets say you want to descend 5000ft, and you are currently at 10000'. You have an IAS of 250kts so, lets say, a groundspeed of 300kts - your RoD is 1700fpm - is the following calcuation correct?
Using the right angle triangle - you know the vertical as its the height you want to lose - 5000'
It takes 3 mins to lose the altitude at your RoD. Therefore travelling at 300kts you will travel 5nm/min so you will cover 15nm which is 24135m which is 79183ft. So using TAN can you do Inv Tan (O/A) = descent angle?
Inv Tan x (5000/79183) = 3.61 degrees? sounds about right but maybe its just luck that the wrong calculation brought an answer that looks about right...