I’m working on an enhancement to the copter battery failsafes that will calculate live throughout flight how much battery power is required to execute a complete RTL sequence. Rather than going into the technical details of how, I will get right to the survey questions I need responses to:
Assuming you have a fairly normal copter, not some ludicrously over or underpowered machine, and you have fairly normal ground speed and climb/descent speed parameter settings:
In a climb, what % above hover is the mAh consumption?
In a descent, what % below hover is the mAh consumption?
In level cruise flight, what % above or below hover is the mAh consumption?
Using my solo as an example, it hovers at 20 amps.
In a climb, it is 20% higher than hover at 24 amps.
In a descent it is 10% lower than hover at 18 amps
In level cruise it is 20% lower than hover at 16 amps
I’d like to see if these percentages are generally the same or close enough to the same across as many copters as I can survey here. This will help me determine good default parameters that can apply to most copters.
Please post your data if you know it or can check it the next time you fly. Thanks!
At very minimum, you should specify vertical speed.
Without it the numbers are meaningless.
At best, you would provide whole test methodology , describe parameters to set climb/ descend parameters, and ask pilot to wait for reaching full vertical speed with some horizontal speed in a given mode… that would give you better data.
Good to see you are working on better energy estimate.
The vertical speed is whatever the operator has set the WPNAV_SPEED_UP and WPNAV_SPEED_DN parameters for. Which is what the calculations will use to determine time in each phase of flight. I have the math all worked out already. I just need to gauge a reasonable variance from hover for each phase of flight.
I’d be interested in providing data from my two work Solos with gimbals/gopro and MAS 1045 V1 propellers if that’s wanted, but I’m having difficulty finding how to filter down segments of the log to get the averages for the data that you want. I have 117 dataflash logs from this year between the two.
I’m currently graphing:
BARO_ALT
GPS_SPD
Curr_Curr
Are those appropriate to help me pick the correct “states” (ascend, descend, forward level flight, hover)?
the target vertical speed affects the numbers you get, trying to have 15m/s climb will use much power just to fight the drag, and having a target of 10m/s will idle motors completely.
So you do not need only data, but sane conditions
I just flew in some for you:
windspeed is 7-8m/s , I did the tests whith groundspeed og maximum 10cm/s(poshold)
battery voltage around 45.5v
Hover 69A
Climb at 2.7m/s is 83A
Descend at 2.4m/s is 55A
Right. This is what I was referring to when I said:
Thanks! That is +20% for the climb, just like mine was. Your descent is -20%, more efficient that mine which was -10%. What was your level cruise flight?
“What was your level cruise flight”
That would be about 69A , I wrote that the wind were 7-8m/s so the “hover” I wrote down was equivalent of a “cruise” with GS about 7-8 m/s
if wind gets significantly slower next few days - I’ll do some cruise speed vs power tests of different speeds.
Yeah your right, forgot the drag. But this is really special from copter to copter. The formulas I gave so far should be applicable to every copter.
If I find the time I will do some comparison between reality and the calculations.
There should be a climbrate which is the most efficient because the drag scales quadratic with the speed. Interesting to know to maximize range on missions.
BTW for the others: amps alone do not give accurate data.
Energy -> [Wh] = W x h
Power -> [W] = A x V
With li-ion batteries, the voltage range of the cells may be quite significant. Therefore my “descents” at the end of the flight actually pull more amps than the climbs during the beginning of the flight.
An energy-based architecture instead of a current-based architecture would be very useful before implementing this in my opinion. Just like @palm369 said, amps alone are not really that accurate. This should be transitioned into Wh (energy), not Ah.
I agree. However we are not presently capturing or calculating the battery’s capacity in watts. And it’s not something I’m looking to take on right now.
