I need to be able to calculate the line-of-sight minimum altitude between two objects on the earth taking into account the objects between them. Calculating LOS is pretty easy and there are numerous online calculators for that, but none of them take into account objects between them.
For example, say I have two communicating sides - a RC pilot and an RC plane. Supposing it can fly 100km (D) away, then what is it's minimum flight altitude H_ant2 to remain in LOS when there is a known obstacle with height H_obs at a distance L away from RC operator who holds the radio at height H_ant1. I would need to have an expression that let's me calculate the minimum flight altitude so I could draw a function graph which shows flight altitude in respect to distance from the RC pilot.
The exercise seemed pretty trivial at first, but after doing little math I found it to be out of my scope of knowledge because there are a lot of variable and constraints to take into account.
If someone could provide me an formula for calculating minimum altitude I would be very grateful. However if someone can just point me into right direction and help me with an explanation then that would be of help to. I know there are probably numerous ways to solve this, but I would like to stick with the most easiest to grasp and implement (that means no dif. equations please).