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Flight time and efficiency

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Hi,
I'm still trying to wrap my mind around calibrations and their effect on performance. I've been reading posts regarding higher capacity batteries to increase flight time but I've been considering what other factors might be involved. Another post mentioned the center of gravity and I've been thinking about how this might effect things. I did notice that after calibrating the accelerometer on a perfectly level surface that when I pick up the drone by putting my fingers under the right and left prop arms the drone leans slightly backward ( the rear skids touch the ground first). In one of the battery posts I saw a reference to moving the camera forward to compensate for a heavier battery. Something to consider but why should this be of concern? I'm still not sure. Other posts mentioned very short flight times in windy conditions and another referenced much longer flight times when flying very slow. I next considered the effect of a steady crosswind and was thinking that just a variation in the power applied to the props should easily compensate and that didn't seem it would have much effect on the amount of power required but then I realized that the crosswind increased the effective weight that had to be overcome to maintain altitude. So considering the factors such as inertia, wind resistance. center of gravity all come into play and have me somewhat bewildered and suspecting that there are things that I haven't even considered. I'd like to hear what others think about or have to add to any of this.
Jim F.
 
You just had to complicate everything, didn't ya?o_O:)

Actually, I'm rather glad someone, in this case you, has taken a step back and considered there's probably a heck of a lot more to making a multirotor fly, specifically with things that can influence flight time, than what is readily apparent. You brought up some things that are indeed relevant. Rather than add to them and write another marathon post I'd like to see others dive in with their input.
 
Bottom line is anything that makes the motors work harder will drain the battery faster. Flying faster, dramatic altitude changes, wind, added weight, changes in CG, and rapid direction changes are all going to work against you.
 
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From what I've seen the higher capacities can give a few extra minutes according to some.and ohers no change, you pays your money and take your chance, best to just fly it and learn it's strengths and weaknesses, take on board what others say but don't become obsessed with having to find a conclusion or answer for everything, like a car they will all perform slightly differently.
 
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I think your trying to over analyze all this. Just go out have fun and fly.
There's been a fairly high number of posts regarding batteries and how to get the most out of them. Not having a lot better to do I was considering the flip side of the coin. I enjoy doing this.
 
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Hi,
I'm still trying to wrap my mind around calibrations and their effect on performance. I've been reading posts regarding higher capacity batteries to increase flight time but I've been considering what other factors might be involved. Another post mentioned the center of gravity and I've been thinking about how this might effect things. I did notice that after calibrating the accelerometer on a perfectly level surface that when I pick up the drone by putting my fingers under the right and left prop arms the drone leans slightly backward ( the rear skids touch the ground first). In one of the battery posts I saw a reference to moving the camera forward to compensate for a heavier battery. Something to consider but why should this be of concern? I'm still not sure. Other posts mentioned very short flight times in windy conditions and another referenced much longer flight times when flying very slow. I next considered the effect of a steady crosswind and was thinking that just a variation in the power applied to the props should easily compensate and that didn't seem it would have much effect on the amount of power required but then I realized that the crosswind increased the effective weight that had to be overcome to maintain altitude. So considering the factors such as inertia, wind resistance. center of gravity all come into play and have me somewhat bewildered and suspecting that there are things that I haven't even considered. I'd like to hear what others think about or have to add to any of this.
Jim F.
We just have to wait for more efficient batteries.. yes, much more efficient before we'll get any longer flight time! And be 100% sure that these batteries will NOT fit in any now excisting drone. Cause "they" will sell new drones.... :eek:
 
I think your trying to over analyze all this. Just go out have fun and fly.

Flight time is what it is, and there is little we can to add any significant amount of flight time to what we have. What is significant? You tell me what it means to you. In my opinion 1 minute even 2 is not significant, 5 minutes is where I would realize any true benefit, anything less in not worth even thinking about, let alone paying extra money for. Aftermarket high mAh batteries do not provide a significant increase in flight time, only coming in around 1 minuter longer. Even using a Plus HV battery in an H480 does not add any significant flight time.

Keeping proper CG balance will always help flight times a little. But significantly? There that "S" word again! Is it even worth the trouble and work to re-position the camera for a possible minute or less?? I'm with AH-1G, don't waste time overthinking it, spend that time enjoying it.:cool:
 
Flight time is what it is, and there is little we can to add any significant amount of flight time to what we have. What is significant? You tell me what it means to you. In my opinion 1 minute even 2 is not significant, 5 minutes is where I would realize any true benefit, anything less in not worth even thinking about, let alone paying extra money for. Aftermarket high mAh batteries do not provide a significant increase in flight time, only coming in around 1 minuter longer. Even using a Plus HV battery in an H480 does not add any significant flight time.

Keeping proper CG balance will always help flight times a little. But significantly? There that "S" word again! Is it even worth the trouble and work to re-position the camera for a possible minute or less?? I'm with AH-1G, don't waste time overthinking it, spend that time enjoying it.:cool:
A forum is a place where someone can discuss items of interest to them. I don't consider posting here wasting my time.
 
After my initial post I recalled the procedure to calibrate the accelerometer while airborne in no wind conditions. I'm wondering if this would somehow take into account the displaced center of gravity. When I first read of the airborne method I had no idea why it would ever be desirable to do it that way. Perhaps to compensate for the displacement? Still confusing to me.
 
I don't consider posting here wasting my time.
Hold on a second! I never said it was a waste of time to post a question here, and I don't even know how it came across that way. I was only saying it was a waste of time to peruse an insignificant increase in flight time. Please read my post again, I made no such statement.:oops:
I recalled the procedure to calibrate the accelerometer while airborne in no wind conditions.
Please direct me to this "Airborne " accelerometer calibration procedure. I have never heard of this before and I want to know more. Was this a post on this forum or a YouTube video? I have never come across this in the manual..
 
Hold on a second! I never said it was a waste of time to post a question here, and I don't even know how it came across that way. I was only saying it was a waste of time to peruse an insignificant increase in flight time. Please read my post again, I made no such statement.:oops:

Please direct me to this "Airborne " accelerometer calibration procedure. I have never heard of this before and I want to know more. Was this a post on this forum or a YouTube video? I have never come across this in the manual..
It's described on page 45 of the revised user manual (TYPHOON H USER MANUAL Vcho3-2.pdf). It's the only method described in the Typhoon "USER MANUAL RS-V1.2 "
 
Did all these calibrations really needed to be done? Or just an inquisitive mind?
 
Did all these calibrations really needed to be done? Or just an inquisitive mind?
I suspect that none of the calibrations are required but simply result in smoother, more efficient performance.
 
Since you enjoy doing this, some of us view your reply's to be argumentative rather than productive.
Why don't you actually experimenting with your aircraft, then give us the results?
We can talk/argue/question and give self opinionated answers for every nook and cranny until stupid sets in, it's not worth it!
 
t's described on page 45 of the revised user manual (TYPHOON H USER MANUAL Vcho3-2.pdf). It's the only method described in the Typhoon "USER MANUAL RS-V1.2 "
I see you are talking about an H480 and a procedure that is not the the factory manual, I have Plus and this is not a Plus procedure.
Since you enjoy doing this, some of us view your reply's to be argumentative rather than productive.
Why don't you actually experimenting with your aircraft, then give us the results?
We can talk/argue/question and give self opinionated answers for every nook and cranny until stupid sets in, it's not worth it!
Ditto!
 
I suspect that none of the calibrations are required but simply result in smoother, more efficient performance.

You might want to revisit that stand if you ever experience a flyaway or flight behavior you didn't expect. Consider it, at the least, as cheap insurance.
 
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After my initial post I recalled the procedure to calibrate the accelerometer while airborne in no wind conditions. I'm wondering if this would somehow take into account the displaced center of gravity. When I first read of the airborne method I had no idea why it would ever be desirable to do it that way. Perhaps to compensate for the displacement? Still confusing to me.

Any effort to "calibrate" accelerometers while the aircraft is in flight or in motion will be an exercise in futility, and quite possibly cause more harm than good. The initial accelerometer calibration is probably the most critical of all the calibrations performed on a multirotor. A compass calibration really isn't necessary if GPS is not also employed. You can fly without a compass or GPS, you won't fly without accelerometers.

We need to consider that a multirotor disrupts the four forces of flight commonly used to describe what it takes to make an airplane fly. An image showing a depiction of the usual 4 forces of flight is attached for casual reference. The directional arrows represent those forces. For a winged airplane we have lift over weight, thrust over drag. For a multirotor we have thrust over weight and thrust over drag. Although a propeller does generate a lift vector, for our purposes were dealing primarily with thrust. There is no lifting body to assist the flight of a multirotor. They are, for the most part, 100% dead weight.
Four-Forces.jpg
Because a multirotor does not have wings it does not generate lift. Lift is replaced with thrust, with that thrust generated by multiple motors. A multirotor differs from an airplane in another way. An airplane does not require gyros or accelerometers to keep the airplane balanced in level flight. That process can be easily accomplished by balancing the forces of flight through power management and control surface trim offsets. Airplanes don't hover (well, some can but that's a subject for another day and a different type of forum) so there's no need of a device that measures very small differences in altitude or air pressure, and having the engine or engines mounted in a manner where thrust is generated parallel to the direction of flight instead of perpendicular to any flight direction other than in the vertical plane there's no need for devices to monitor disturbances from horizontal that would disrupt level or hover flight.

Because a multirotor uses multiple motors to stay in the air and remain controllable there needs to be a means to rapidly sense any imbalance and send signals to a computer that will tell individual motors what they need to do to keep the aircraft level. A multirotor in level flight or a hover does not have all the motors turning at the same speed, ever. Because no air mass is ever stationary the motors on a multirotor are in a state of constant RPM flux to deal with minor air movements that disrupt the attitude of the aircraft. Every motor is constantly speeding up or slowing down in some amount to maintain the balance necessary to provide hover flight or just keep the multirotor generally level for the direction of flight being commanded. Guess what devices perform that task? The accelerometers.

Accelerometers should always be calibrated with the aircraft motionless. Ideally the aircraft will be sitting level or very close to level in an environment where the surrounding air mass is as still as possible. Although you will rarely, if ever, see a stationary accelerometer display a zero value (because the earth is always moving and gravity varies slightly) a motionless accelerometer should produce a value that falls within a very narrow range of motion. Our flight controllers use a motionless accelerometer as a zero reference point. As we do not have the ability to input a force offset to correct a calibration error due to positional drift over time we might presume our flight controllers have the means to do that automatically.

It is not possible to calibrate an accelerometer in motion, especially those used for a multirotor when the multirotor is in flight. There is for all intents and purposes no such things as a "no wind" condition, something that never happens because the propellers generate wind forces, and the FC is continuously adjusting motor speeds to maintain balance. This is why is it so important that we do not disturb the aircraft during the initial power up/boot up sequence. During that sequence the accelerometers perform a self calibration. If you have ever seen a multirotor with a good flight controller drift all over the place in hover on a calm wind day, and I know you have, the cause of that was most likely failure to perform the initial accelerometer calibration, moving the aircraft during the boot up sequence, or zero position drift occurring over time that would require a new calibration to correct. The accelerometers never established a zero reference point.

Just for fun consider how a multirotor FC has to deal with center of gravity issues. Unlike an airplane the pilot does not have the ability to offset elevator trim to deal with a minor imbalance, although our FC's do essentially the same thing using a different method. The accelerometers "sense" the imbalance created by the weight that offsets the CG. So they send info to the FC that causes the FC to add power at the motors that need to carry extra weight while reducing power to motors opposing the "heavy lifters". In aviation there's no such thing as a free lunch so any imbalance always ends up costing us something in fuel, distance, or flight time. As we use batteries our fuel and flight time are pretty much the same thing. Our aircraft do not have a glide ratio as there is nothing but the motors to provide thrust for lift. An airplane uses it's wings to generate 40% or more of the lift needed to keep it in the air, making them vastly more efficient than a multirotor.

Accelerometers are very important and we should treat them accordingly. I don't know anyone that could fly a multirotor and maintain control without them.
 
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