I'm going to the high country in Colorado next month and would like to use the solo up there. Has anyone used a solo higher than 12,000 ft ASL? Is there a published service ceiling?
Maximum Service Ceiling?
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It will depend on density altitude, battery condition, and weight. So max service ceiling is generally between 12,000 and 15,000ft. Bear in mind that even if you can take off and fly around, you will be doing so at much higher throttle than normal. The solo normally hovers at about 35% throttle. Up that high it will take a lot more power to hover. And even more to fight wind. Which also means you have less wiggle room fight wind. The controls will be less responsive as well. So take off and do some close in maneuvering to get a feel for it first.
You might also investigate slightly longer, slightly higher pitch props. I think there are 11x5s available from MAS....
Thank you all. I have already installed the Master Air Screw propellors. I am using a GoPro 3 White with the gimbal. Nothing additional to add weight.
Hmmmmm.....Service ceilings are usually the result of inadequate air density for the engines, which use oxygen, to perform.
I believe that more power (current/amperage) would not be consumed at higher rate at a higher altitude. The density of air would change, but the weight of the UAV would not. Therefore the same amount of thrust would be constant to hover regardless of altitude. This would certainly require the motors to spin faster to achieve that thrust, and less "head room" ( until maximum speed of motor is reached) would be available, but the current draw would approx. stay the same. The load on a motor is the determining factor in "power" being used.
You're talking around it, methinks. In order to hover at higher density altitudes, the motors will have to spin at higher RPM to generate the necessary thrust. (Since the ESCs on SOLO are fancy PWM generators, we are really varying the output voltage to change the speed on a motor) So, holding voltage constant (or hold current constant if it pleases you), there will HAVE to be an increase in current (or voltage). W=VA, so you will have an increase in the wattage drawn per unit time, which is the definition of power. So there absolutely will be an increase in the power drawn. The service ceiling in this case is related to the batteries ability to supply current.
Nope. The service ceiling is ONLY dependent upon the ability of the motors to spin at a speed to produce thrust equal to the weight of the aircraft! If you run out of voltage or current that wont allow to motors to spin as fast as needed then and only then will a service ceiling be reached (or of course if motor design/prop design limits are reached). The motor ONLY sees a load per wattage. It does not care what the rpms are as long as the load is the SAME. Motor with Y amount of load draws X amount of current at Z rpms. Same motor with 1/2 Y of load will spin faster with same amount of wattage, or will spin at same speed with less wattage. Wattage/fuel consumed is ALWAYS load dependent. It is that way in ANY power plant.
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Not necessarily. LESS load will cause the motors to spin faster also! Less load with subsequently LESS amperage will also cause the motors to spin faster (until the amperage falls below a certain threshold)
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I'm not sure what's being debated here. If you're suggesting it will not require more power to spin the motors faster due to less sense air, that is simply incorrect.
Dobie has an interesting point, however. Yes, it takes more power to spin motors faster in general, HOWEVER there is less air resistance against the props at higher altitude, which means that the props will spin faster given the same power (the air is not slowing down the props as much as at lower altitudes). Therefore, at higher altitudes, given the same power, we will have BOTH an increase of prop speed AND a loss of thrust due to the lower air density. Which one "wins"? I suspect that the answer can be deduced by taking it to the limit of zero air pressure (outer space), in which the props spin free of all resistance, but produce NO thrust.
Last summer I flew above 12,000' ASL in Colorado using both the stock and APC 11" props. The Solo was more stable with the APCs. Flight times were reduced about 20% I would say.
Yes. That is my contention. There may be a slight decrease in flight time due to the parasitic drag of friction within the bearings caused by the increased rpm but that should be negligible. Additionally, with the increase in altitude comes a decrease in ambient temperature. This will result in the motors running cooler, which should allow for more voltage/current to be applied (if available from the battery) than at lower altitude, resulting in even more rpms
As those the standard APC 11x4.5 multirotor props? Anything special to do in order to mount and use them?
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I'm sorry but that assumption is simply not true. Power consumption increases significantly. And as such, flight time decreases significantly. Controllability suffers noticably as well.
They are the standard props; but they must be reamed out to fit the Solo motors. Rich West did a video on this I believe. I followed his steps and glued the nuts to the props.
Here is some info:
11" Props on stock Solo motors
I like the 11" in cool air at altitude, but feel they make the motors hotter in the warm summers here in AR. So I don't tend to use them for general flying. I do think they make the Solo more stable but slightly more sluggish; could be an imagined or real perception. At altitude I think they are worth the effort.
The kv parameter of the motors and battery voltage will limit the maximum RPM, but power consumption will decrease (not increase) along with the decrease in thrust that can be attained.
A larger prop is the simplest solution to compensate for thinner air. The other solutions would be to use higher propeller pitch, higher kv motors, or higher battery voltage. In each case, total power consumption at hover should remain about the same. Power consumption in forward flight should actually be slightly less at the same airspeed. There could be small variations due inefficiencies if the the motors were not correctly propped, i.e. not loaded near the peak of their efficiency curve. Propellors have an efficiency curve also. As pitch increases, the thrust to drag ratio degrades (at least in hover).
A larger prop is the simplest solution to compensate for thinner air. The other solutions would be to use higher propeller pitch, higher kv motors, or higher battery voltage. In each case, total power consumption at hover should remain about the same. Power consumption in forward flight should actually be slightly less at the same airspeed. There could be small variations due inefficiencies if the the motors were not correctly propped, i.e. not loaded near the peak of their efficiency curve. Propellors have an efficiency curve also. As pitch increases, the thrust to drag ratio degrades (at least in hover).
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