I'd like to produce maps for gliders in mountains.
I'm looking to display the reachable area by a glider taking off from a given point (obviously with the corresponding DEM).
For a first approach I'll suppose that we are in static air, no thermal ascent, no wind.
So like water gliders only go down.
Gliders have a specific slope (the glide ratio).
I started thinking that my problem is similar to a flood inundation analysis. But I cannot find how to input a specific slope in any of the hydrology modules I explored.
@Spacedman propose a first approach by creating a raster representing a shallow cone centered on the take off point and having the glide ratio as slope. It is a good approach without any obstacles.
Imagine you have an obstacle on the straight line for example there is a cylinder.
The area behind this cylinder may appear as "reachable" but the distance behind the cylinder from the take off point is (straight D)+𝚷(cylinder_radius). So obviously there is 𝚷(cylinder_radius)/glide_ratio difference in height.
Is there another approach that I could use?
Implementation of approach without any obstacles:
G is glide ratio (ie: ∆D/∆z)
(x₀,y₀,z₀) is taking off point
(x,y,z) are coordinates of a point on the glider reachable area
(x,y,zₑ) are coordinates of the projected point on the earth DEM
Hₑ is height over the ground
Obviously if Hₑ≥0 it is reachable otherwise not.