The quads in question are the Hubsan H107D and H107C.
On a 380 mAh battery, the H107D flew for a little over 4 minutes, while the H107C flew for a little over 10 minutes. I suppose the difference is due to the FPV camera that is always on on the H107D. There is a camera in the H107C, but it is on only if there is a microSD card installed (and I do not have one yet).
On a new 500mAh battery, the H107D flew for over 6 minutes, much as I expected given the flight time on the 380 mAh battery. But the H107C flew for only 8 minutes on a new 500 mAh battery. I do not understand why.
Is there a good resource that shows the math relating the key properties of the batteries, the motors and propellers in use to the flight time? (I am no stranger to complex mathematical models; I am just a stranger to this sort of engineering.)
I haven't done enough testing to provide statistically significant results (I have 5 500 mAh batteries, supplied as an upgrade to the 380 mAh battery they come with, so I could spend weeks testing enough to get statistically significant results), but this result has me puzzled. I know the 500 mAh battery is longer and heavier than the 380 mAh battery (but both fit the Hubsan quads I have), but should that result in such a reduction in flight time? I thought the bigger battery should result in a longer flight time. Did I waste my money getting the 'upgraded' batteries?
Thanks
Ted
Replies
You are right in your latest thinking - weight is a massive influence along with simple stuff like prop balance etc.
The weight of the FPV equipment will have a much larger impact then it's current draw which over a few minutes flight will be tiny compared to the power used to remain airborne.
Thanks Ben
OK, then, I assume that LiPo batteries that provide a lot more energy will also weigh more, and thus, for a given set of motors, may be counter productive. So what, then, is the trick to get longer flights? More powerful motors along with the bigger batteries, and lighter bodies (but how does one do that unless on has a very good 3D printer? Speaking of a good 3D printer, is there one, or a complete kit to make one, that is up to the task of making extremely light and yet extremely durable, bodies and frames this small?
I have all the parts to make another Hubsan H107C, but with the enhanced motors that are available for it. Would that, with the stronger motors, get a better result from the 500mAh battery?
Following on with what you have said, how does on balance a propeller? You say that is simple, but I am so new at this, I have no idea how to do that. What other 'simple' things should I look at, and is there a resource that shows/describes what to do and how? I only started studying all this about 3 weeks ago (but, I am an old scientist, and so am a quick study).
Also, are there other propellers, such as ones that are slightly larger or smaller, with 3 or 4 blades, and at different angles, that could provide a better result.
What would you expect, in terms of flight length, from something like the Walkera Y6 Scorpion, which has 2 motors and propellers on each of 3 arms? With the extra motors/propellers, should it be able to carry a larger payload in batteries, and thus obtain a better flight length? What about the Walkera X8 Spacewalker, which has 8 arms, each with a motor and propeller? If that could provide a benefit in terms of flight length, what about putting two motors and propellers on each of the Spacewalker's arms, analogous to how Walkera turned a tricopter into a hexacopter? Just how far could one go?
I guess part of the trick would be that the increased number/power of the motors should be associated with a weight that does not increase as fast as the weight of the motors (and are there more powerful motors that draw less energy while weighing less and providing more thrust?), and that the increase in energy consumed by the extra motors should not increase as fast as the energy stored in the batteries. Will a 2Ah LiPo battery weight 4 times as much as a 500mAh LiPo battery? But then, that brings me back to the mathematical relations among all these variables. I still need a good source on that.
I guess, in terms of what I need, I need not only pointers to information I can use, but also to parts suppliers that can provide what I need in Canada (or that can ship to Canada).
Thanks
Ted
Yes, yes, and yes.
The flight conditions and profiles were identical, and I charged the batteries fully.
I repeated the tests today, in identical conditions, with the same results.
A subjective impression (since I do not have any means of weighing these things), is that the H107D is lighter than the H107C, and thus benefits more from the extra power while the extra weight of the bigger Battery stresses the H107C's motors more, making them draw more energy and reducing the amount of time available to fly. Is there another explanation? I am guessing the FPV camera is why, even with the benefit of the bigger battery, flight times are 25% shorter for the H107D. (Is there a way to turn off the FPV camera/video feed, so that the flights can be more comparable?).
In any event, I want to conduct some experiments with copters the size of the Hubsan, and it would be useful to have a mathematical function that relates all these things...
Thanks
Ted
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