# Calculating the maximum altitude of a drone [duplicate]

Is there an equation to find the maximum altitude that a drone or quadcopter can fly to ?

In the US, drones are required to stay in visual range. How far away can you see?

There is also a free AOPA app that you could look into to help keep you out of trouble (or form hurting me as I fly around in my airplane at 145 MPH trying to keep an eye out for smaller things like birds and drones):

B4UFLY is an easy-to-use smartphone app that helps unmanned aircraft operators determine whether there are any restrictions or requirements in effect at the location where they want to fly.

Key features of the B4UFLY app include:

clear "status" indicator that immediately informs the operator about the current or planned location. For example, it shows flying in the Special Flight Rules Area around Washington, D.C. is prohibited. Information on the parameters that drive the status indicator A "Planner Mode" for future flights in different locations Informative, interactive maps with filtering options Links to other FAA UAS resources and regulatory information

• Re visual range, I could quite easily strap a drone to my backpack and hike to the summit of Mt Whitney, Pike's Peak, or many another 14K ft mountain. So would the drone be able to take off at that altitude? (I once was given one of those little toy electric helicopters, which would hover in the Bay Area's sea level air, but not at my ~5000 ft home.) Jun 27, 2018 at 16:45
• I don't know. The electric motors are likely expecting a certain amount of resistance from the prop pushing on air, which in turn has an impact on current flow. The ESC in the drone may limit the speed the motor can turn (RPMs). With the less dense air, the props can spin freer and the motor might overspeed or overcurrent if not limited by the ESC. If the ESC does limit the RPMs or current, than maybe you could use blades with more pitch to make up for the less dense air and still be able to fly. A nonturbonormalized gas engine loses HP with alititude, I'd have a hard time getting to 14K. Jun 27, 2018 at 18:55
• I was flying this morning, having to pick out a 34' wingspan/30' length aircraft 2 miles away to follow in for a landing. I knew what I was looking for and where, and it was white moving 100 MPH against a green trees background. I wouldn't be able to pick out a 2-3 foot drone barely moving (relatively) that far away. Jun 27, 2018 at 18:59
• It's not just a matter of power, it's that the less dense air produces less lift per rotation, and of course there are going to be purely mechanical limits on the max speed of an electric motor. (Non-turbo'd piston aircraft get a double whammy, of course.) But my point was that if your drone could fly from the summit of a fourteener, you'd have no trouble keeping in visual contact, while 14K ft from sea level would be a different story :-) Jun 28, 2018 at 17:55
• Try different pitch blades to make up for the lower density, or perhaps larger diameter or wider chord. If you and the drone are both at 14K, then yes I suppose you'd be able to keep it in sight. Jun 28, 2018 at 18:00