Math Equation of Flight Time VS Weight..

[rfernandez]

Has any of the engineers in this forum have come up with an equation for flight time versus added weight?
FYI forget about the 1 second per gram bit.. it does not add up, My Taco-RC gimbal with FC-200 camera weights in at 165g
Now if I use that in an equation of FT= AW/time. Where 165g /60 = 2.75 (2min. 45 sec). FT= flight time, AW = added weight.
Variables to take in to account are the added electrical consumption of the gimbal motors and gimbal controller.

I wrote an email to Taco-RC and their response was that the 2208 motors should consume less than 1 amp. I looked up the specs and i found the following: Constant current is 6A, No load current is 0.6A And Peak is 12A.

If you take the average weight of a stock Phantom is 1165g RTF. Mine with the gimbal weights in at 1330g and I am getting on average 16.5 to 17.5 min landing with at to around 18% of battery left.
Now something here does not add up, so there has to be a valid equation to predict flight time reduction to weight added,

Now that is something to bake ones noodle... :arrow: :evil:

 

[grochester]

Possibly a non-linear equation. For example, extra motor rotations required for lift may not be directly proportional to extra weight lifted due to the fluid dynamics of air and efficiency of propellers.

 

[Cr8tive_leo]

Air density/pressure, wind, all sorts of numbers for the equation. Also the health of your battery.

 

[brushlesheaven]

Thats right and did anyone do any testing on
our original P2V lipo battery. I know from my expierience so fare
with lipos that there is no 2 the same 5200 mah ( real 5200 mah )lipase out there...

 

[SlackerATX]

How balanced the gimbal is...wind speed...aggressive flying. In general what % of the time the gimbal sits outside it's natural position and the force required to maintain that position. (Not to mention the obvious power and PID setting that will directly impact battery consumption)

 

[rfernandez]

I was not looking for a precise equation but a general rule of thumb. I know about the variables and we don't have all the numbers needed to make it a precise number< but close is good enough to get an Idea.
Here are the numbers that I do have:

Battery at 100% at take off
landing at around 18% capacity
Total Flight time 16:32
Gross wight 1330g
Battery Life at 93%, No 2 at 93% no. 3 at 98%
Stock Props. near perfect balance (video is perfectly smooth )
TACO_RC Gimbal with V3 Shell
ALT Pressure at 29.98
winds 220/5 kts
No aggressive movements.

Roll: P=10, I=.1, D=19, Power=110,
Pitch: P=10, I=.1, D=19, Power=90,