So true, Scotty, so true. (Or “I can’t change the laws of physics” to give the proper quote before I am lynched by the trekkie police!)
It’s pretty simple really. A multirotor is a flying machine carrying a fixed mass. That mass is comprised of the airframe and associated flight components, the batteries and the payload.
Now, with the payload I carry on my octocopter, I know, with the batteries I use, that I will get about 10 minutes flight time under normal operational conditions. This will leave me with about 20% charge in the batteries and if necessary a bit of oomph to deal with any issues that may arise on return and landing.
Most enquiries include something along the lines of:
How long can it fly? What weight can it carry? How high can it go? How fast can it go?
So I generally reply asking what the customer would like to achieve. Again, often the reply is something along the lines of:
Up to an hour flight at an altitude of 1000m carrying a 5D. Now, that is a fictional example but some of the actual enquiries have been even less realistic. Let me tell you now, there isn’t a multirotor in the world that could do that at the moment. Some companies claim long flight times. I have seen up to 90 minutes listed. I don’t believe that, at least under operational conditions. If they did, it would be a low hover so ground effect assists lift, in non-working conditions with a minimal payload. If they make these claims, ask them to provide an uninterrupted flight video showing the mass of the payload and the conditions of the test and the battery condition before and after (we will be doing this with Versadrones stuff when we have some time).
With current battery, motor and propeller technology there always has to be a compromise within the total aircraft mass. You can carry a heavy camera, but not for long. You can fly fast, but not far. You can increase endurance at the expense of payload.
If we could make a machine that would carry a 5D for 45 minutes, we would sell thousands. At HexCam and Versadrones we like to give you realistic flight times and capabilities, so our flight times will always be under operational conditions, eg. carrying a particular camera and with some moving flight and hovering as you would expect in a normal aerial photography job.
So, can we build you a machine that will carry a 5D for 45 minutes? No
Can we build you a machine that will carry a 5D for 10 minutes? Yes, and it’s amazing what you can get done in 10 minutes if you plan properly.
Can we build you a machine that will carry a GoPro for 20+ minutes? Yes.
Will it be the same machine for both? No. Think of it in terms of cars… You wouldn’t drive a pickup truck in an F1 race. We try to match the machine to the job. Our new heavylift octocopter (below) will carry a GoPro of course, but not as efficiently as a smaller machine optimised for the job. Our small GoPro machines won’t get off the ground if you gaffer tape a 5D to them (goodness knows, we’ve tried!).
Ye’ canna’ change the laws of physics!