The point of the exercise is to quantify the effect of additional weight on flight times for the stock Phantom, to determine whether the effect on flight time is linear or more complex, and if linear, to determine a ballpark predictive figure of reduction of flight time versus added weight.
The craft: a stock Phantom (with square LED electrically unconnected stuck on the door), nothing attached to camera holder slot, stock props (balanced), stock battery (SAME FOR EACH FLIGHT), full charge on the stock charger, stock TX, continuous hover at 3-4 feet in GPS/Atti mode.
The end points: 1st warning level determined by the beginning of flashing red lights. 2nd point was, after a period when progressively more throttle was needed to keep the craft hovering just off the ground, the sudden, dramatic complete power failure when the craft would drop precipitously. Had it not been only inches off the ground...it would have crashed.
1st flight, stock, no additional weight. Weight = 0 1st point 10' 30” 2nd point 13 '45”
2nd flight Hero2 in protective case, bolt, nut W = 185.1 gm 1st 6' 20” 2nd 10' 45”
3rd flight above plus additional weight W = 364.4 gm 1st 3' 26” 2nd 8' 40”
The first flight, a bare, stock Phantom, is on the ZERO weight line
The second flight represents a mid-range load on an unmodified craft.
The third flight represents a near max recommended load for a stock Phantom.
The relationships appear to be reasonably linear, meaning that generalized observations and predictions are reasonably accurate throughout the loading range at least to near 400 grams. Given that most of the forces (gravity, primarily) are constant, perhaps that should NOT be surprising. As the load increases, the first warning, based on a set level of voltage drop, occurs progressively earlier. For reasons that are less apparent, final complete power failure does not occur at the same rate as the 1st warning point, giving, with heavier loading, a progressively drawn out '”gray zone” when the warning lights are flashing, the craft is wanting to descend and it is taking progressively more throttle to keep it off the ground.
Whereas in the first and second flights the 2nd endpont, complete power failure, was sudden and precipitous, on the third, most heavily loaded flight, THAT endpoint was not not reached. Instead, the slow, progressive loss of power at full throttle made it eventually impossible to keep the craft off the floor. Had the craft been at altitude, it would have been descending even at full throttle, and probably would soon have lost power precipitously. But in this case, once the craft was on the ground and I could not lift off....I simply shut it down.
This observation is completely consistent with that of the poster who loaded his craft down with 1.5#. The craft could remain airborne for only 2 minutes. He then unhooked the weight and flew the UN-weighted craft for another 8 minutes.
So....to tweak the graph, I plotted TIME REDUCTION from unweighted flight time (in seconds) by WEIGHT ADDED (in grams).
The first flight is at the 0 weight, 0 time reduction junction. Displayed this way the data allows me to calculate the figure I hoped for. Assuming a linear or near-linear relationship, from the first addition to a stock, bare craft to the final nut or bolt on a fully tricked out (but otherwise stock) craft, each GRAM of weight is going to cost me 1.2 seconds to first warning light.
And, while I might KNOW that I have three or four minutes on a fully loaded craft after the first warning lights flash before I lose the ability to hover, the quantity of expensive gear to be lost and the uncertainties involved dictate that I will bring it craft down and back quickly once the warning sequence begins.
I have just received 2 new sets of props, 9” 2 blades and a set of 3 blades. Since the efficiency of these props will be different, but constant, I expect flight times to change, hopefully for the better. Whether those props efficiency under progressive loading will give the exact same linear slope as the stock props....upholding the 1 gram = 1.2 seconds reduced flight time of the stock props remains to be seen. But I predict it will be close.
The 1 gram = 1.2 seconds reduced flight time figure for any addition above stock weight is a relentless, cumulative burden. If I want a gimbal and one model is $300 and weighs 200 g (WITHOUT camera) that is necessarily going to reduce each and every flight by 3' 20”. Another popular gimbal weighs 180 g at $100 less, and the most expensive claims to weigh only 180g WITH GoPro 3 attached. Those differences in weight create significant to enormous losses or savings in flight time.....each and every flight.
The GoPro 2 weighs 100 g, the GoPro 3 only 74 g. That difference alone is almost 31 seconds per flight. The GoPro 3+, just announced this morning, weighs 59 g. All the better bells and whistles aside, that represents 50 seconds longer flight over the GoPro 2. I only have the GoPro 2. Where do I want to put my money for the next addition....and what will be the gains...and the losses.
Having a solid figure for weight = lost flight time allows me to consider that further dimension in pros and cons for every possible alteration and $ spent.
The craft: a stock Phantom (with square LED electrically unconnected stuck on the door), nothing attached to camera holder slot, stock props (balanced), stock battery (SAME FOR EACH FLIGHT), full charge on the stock charger, stock TX, continuous hover at 3-4 feet in GPS/Atti mode.
The end points: 1st warning level determined by the beginning of flashing red lights. 2nd point was, after a period when progressively more throttle was needed to keep the craft hovering just off the ground, the sudden, dramatic complete power failure when the craft would drop precipitously. Had it not been only inches off the ground...it would have crashed.
1st flight, stock, no additional weight. Weight = 0 1st point 10' 30” 2nd point 13 '45”
2nd flight Hero2 in protective case, bolt, nut W = 185.1 gm 1st 6' 20” 2nd 10' 45”
3rd flight above plus additional weight W = 364.4 gm 1st 3' 26” 2nd 8' 40”
The first flight, a bare, stock Phantom, is on the ZERO weight line
The second flight represents a mid-range load on an unmodified craft.
The third flight represents a near max recommended load for a stock Phantom.
The relationships appear to be reasonably linear, meaning that generalized observations and predictions are reasonably accurate throughout the loading range at least to near 400 grams. Given that most of the forces (gravity, primarily) are constant, perhaps that should NOT be surprising. As the load increases, the first warning, based on a set level of voltage drop, occurs progressively earlier. For reasons that are less apparent, final complete power failure does not occur at the same rate as the 1st warning point, giving, with heavier loading, a progressively drawn out '”gray zone” when the warning lights are flashing, the craft is wanting to descend and it is taking progressively more throttle to keep it off the ground.
Whereas in the first and second flights the 2nd endpont, complete power failure, was sudden and precipitous, on the third, most heavily loaded flight, THAT endpoint was not not reached. Instead, the slow, progressive loss of power at full throttle made it eventually impossible to keep the craft off the floor. Had the craft been at altitude, it would have been descending even at full throttle, and probably would soon have lost power precipitously. But in this case, once the craft was on the ground and I could not lift off....I simply shut it down.
This observation is completely consistent with that of the poster who loaded his craft down with 1.5#. The craft could remain airborne for only 2 minutes. He then unhooked the weight and flew the UN-weighted craft for another 8 minutes.
So....to tweak the graph, I plotted TIME REDUCTION from unweighted flight time (in seconds) by WEIGHT ADDED (in grams).
The first flight is at the 0 weight, 0 time reduction junction. Displayed this way the data allows me to calculate the figure I hoped for. Assuming a linear or near-linear relationship, from the first addition to a stock, bare craft to the final nut or bolt on a fully tricked out (but otherwise stock) craft, each GRAM of weight is going to cost me 1.2 seconds to first warning light.
And, while I might KNOW that I have three or four minutes on a fully loaded craft after the first warning lights flash before I lose the ability to hover, the quantity of expensive gear to be lost and the uncertainties involved dictate that I will bring it craft down and back quickly once the warning sequence begins.
I have just received 2 new sets of props, 9” 2 blades and a set of 3 blades. Since the efficiency of these props will be different, but constant, I expect flight times to change, hopefully for the better. Whether those props efficiency under progressive loading will give the exact same linear slope as the stock props....upholding the 1 gram = 1.2 seconds reduced flight time of the stock props remains to be seen. But I predict it will be close.
The 1 gram = 1.2 seconds reduced flight time figure for any addition above stock weight is a relentless, cumulative burden. If I want a gimbal and one model is $300 and weighs 200 g (WITHOUT camera) that is necessarily going to reduce each and every flight by 3' 20”. Another popular gimbal weighs 180 g at $100 less, and the most expensive claims to weigh only 180g WITH GoPro 3 attached. Those differences in weight create significant to enormous losses or savings in flight time.....each and every flight.
The GoPro 2 weighs 100 g, the GoPro 3 only 74 g. That difference alone is almost 31 seconds per flight. The GoPro 3+, just announced this morning, weighs 59 g. All the better bells and whistles aside, that represents 50 seconds longer flight over the GoPro 2. I only have the GoPro 2. Where do I want to put my money for the next addition....and what will be the gains...and the losses.
Having a solid figure for weight = lost flight time allows me to consider that further dimension in pros and cons for every possible alteration and $ spent.
