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
Hi Ted,
It was really an exercise in making a high endurance copter with (mostly) inexpensive parts, he definitely proved it could be done, but you don't really end up with a practical copter for actually doing anything.
As for motors, KDE is currently probably best with Tiger Motor (T-Motor) a strong second. There are also other good manufacturers, but those stand out and aside from supplying very well made motors they actually provide adequate operational specifications at a variety of throttle settings, prop sizes and various number of battery cells. (This is very important for figuring appropriateness for a particular platform.)
There is a lot of talk about Simon K capable ESCs being "better" but for the most part most better ESCs are of similar efficiency. I use Quattro 4 in 1 ESCs where 20 to 25 amps is an appropriate current rating and am quite happy with them. They have several advantages (no need for a power distribution board or rats nest and less interference with the flight controllers magnetometer (compass). Because of their aluminum plate they also have superior heat dissipation to most ESCs. If you need larger ESCs the KDE ones are reputed to be very good and T-motor as well. For smaller ones the better Turnigy ones from Hobbyking have proven reliable.
Currently the proximity sensor problem isn't about the sensors at all, it is about implementation in the "autopilots" firmware.
There is some work currently with optical flow which uses a camera, but there is very little current implementation of proximity sensors for navigation.
This will change, but it is just getting started.
Sonar is not as good at this as you might hope and is very subject to noise, absorbing materials, off angle reflections and beam divergence.
And the inexpensive little angle IR led sensors are pretty much useless.
Laser range finders are starting to be used for simple altitude, and a scanned one could work pretty well for horizontal obstacle / opening detection, but it is barely getting started in firmware and is not a simple project.
The goal of this is "SLAM" simultaneous localization and mapping which permits real time path finding and following.
That is not a simple computer task and generally requires a multicore processor for reasonable implementation (and a whole lot of very high level programming).
There are major university and government projects working on this.
Best Regards,
Gary
Thanks Gary,
Now I have some companies to examine.
If it isn't about the sensors, but rather the firmware, perhaps I can improve things. I have been programming computers for over three decades, and that experience includes some embedded systems and precision agriculture mapping applications. Perhaps with my software engineering experience and quantitative bent, I may be able to contribute something beneficial in that realm.
But if that is the case, what sensors are worth examining, and what size copter would be best to carry them (ideally, if something the size of a Blade 350 QX2 or Walkera X350, or bigger, something that has an effective return home and position holding capability, so that the risk of catastrophe is minimized)? Or is it the case that there are no sensors available that I could use? If labs are making their own, to use to test their software, it isn't feasible for me as I do not have a lab that could make a good sensor.
But then, if it really does require a multicore processor, it will be a while before it can be deployed. On the other hand, I can make my C++ code fly relative to commercially available competitors, so if I can code the firmware in C++, it may be feasible to make it run acceptably on at least the best of the available FC. My ecommerce software, which I have been working on lately, is more than twice as fast as my fastest competition. Your description of the challenges involved in SLAM just make me want even more to try, as soon as I can get/make a good working platform to run my code on. After all, if it was easy, it wouldn't be worth my time. ;-)
Thanks for this. I appreciate it.
Cheers
Ted
I flew bunch of coreless brushed driven toy quadcopter modded into FPV. My tip for you is that any stock coreless brushed driven quad can only carry 30~35% extra from its stock weight, anything beyond that is reduced in performance. All you can do right now is to remove anything that is not necessary on H107D/C main frame such screw, support plastics, thick wires and thing that you can remove without compromising the structural integrity of the quad frame and its flying characteristic. For you reference i got a bunch of cheap mini FPV quad project i did that perform better than bigger brushless multirotor, flew extremely well under various weather condition and longer runtime after huge reduction of weight. Check at my project blog for your tips and references: http://www.supermotoxl.com/FPV/UAV-models-builds-and-flight-reviews...
Also i build 3d printed version too smaller than X4 on other section of my blog. All flew well on 500mah 1s for 12 min. Remember lightweight is everything.
Hi David,
Thanks.
You want to check on the links you provided in that blog, as those for the propellers are broken. But, had you considered something like the Genfam GF 5030 3 blade propeller (or printing your own 3 or 4 blade propeller - something I'd do if I were to seriously investigate 3D printing of multirotor copter parts).
Since you have built 3D printed quads, can you provide links to some of those you made? I see you have a fondness for WL's V929. What do you think of WL's more recent offerings, such as the V262 Skylark and V202 Scorpion? And what about the latest offerings from Walkera? What would you be able to do with Walkera's Y6 Scorpion or X8 Spacewalker? Do you think you could obtain a better result with these (with the greater number of rotors) than you did with the V929 (or that you could with the V222)? Have you tried?
I notice you also didn't say anything about the motors or propellers in that blog. Surely, if one can go the route of making a 3D printed frame/body, one could examine the range of motors, propellers, and batteries that are small enough to make a copter, and even make the propellers with the size and shape your calculations indicate as being optimal; right?
I like the Skylark as the body is made of extremely thin plastic (is there anything lighter than that that can be used for the same purpose) and yet it is almost as durable as the hubsan and MUCH lighter, and I like the notion of having a body to keep things together and protected. Besides, a flying wire frame is just plain ugly. ;-) I find that even though the Skylark is much lighter than the Hubsan, it does not fly significantly longer than the Hubsan on the same battery (though I do not yet have objective measurements on that - it is just a subjective impression for now).
Can one print a body where the frame and body combined weigh less than the Skylark. perhaps making use of bigger batteries feasible: a body and frame whose parts are paper thin, as strong as steel but as light as a feather? The more I think about 3D printing, the more I like the idea, but I have yet to find a source for either the printer or the materials used for printing in Canada at a price I can afford. Think about it: if you can print these things, using plastic or nylon, or something else that is both strong and light, then you can experiment with the number of blades, the length and shape of the blades, and the angle they form relative to the axis on which they spin. And if you're going that route, why not find the best quality, most efficient motor that can be obtained to spin propellers of that size at the right speed? Alas, I still do not have the basic science reference that tells me how to do that, though I am sure such a reference exists because engineers have had to do this sort of thing at different scales for over a century.
For your reference, I have a math and science background, and have mostly worked in computer programming. What I am after is a really tiny multirotor (that is extremely stable when flying, which my reading indicates is improved by having more rotors - but I guess that needs extra long arms and larger propellers), to which I can attach multiple sensors to measure different aspects of the natural environment, and which I can use to develop and test swarming flight, specifically with a view toward detecting objects moving toward it, so the copter can take evasive action and avoid a collision. I'd hazard a guess that a collision between a drone and a bird, or other aircraft, would not do either any good, and so are best avoided (something I'd like to write code to automate - unless that has already been done and deployed in open source software). Obviously, for such experimentation, the copters I use must be as inexpensive as possible, and yet carry at least multiple proximity sensors. Unless the US military is funding you, you really do not want to do such experimentation using the commercial kits as they're much too expensive. If I will crash, I'd rather it be a copter that cost less than $100 to build than a copter made from a 3DR kit costing five to ten times as much. But this experimentation really needs something that will remain in the air at least for the better part of an hour, if not longer. But, I do not yet know if that is possible.
Of course, it will take me a really long time to reach such an ultimate objective (I take the attitude that if it were easy, everyone would be doing it and it thus generally wouldn't be worth doing). For now, I will be following your example, and making my own clone, as it were, of a Hubsan from the spare parts one can get for it. Mine, though, will have the upgraded motors one can get for it and will not have the camera. But, I will do that AFTER I learn how to properly handle a soldering iron (I just bought one, and I think my next tool will be a dremel, followed by a 3D printer that I can rely on to produce quality parts, if such things become available in Canada at a price a working man can afford). And, I will be watching your blog. among other resources, for further information as you make that available.
Thanks again
Ted
Hi Ted,
! The better part of an hour - lets say 45 minutes. !
In order to do that, none of the current truly small quad copters can even come close and nothing under a hundred dollars stands a chance.
45+ minutes is in our world very rarified territory and it takes truly optimized multicopters to have any chance of achieving it.
Everything needs to be optimized:
Lightest frame and big slow props on motors optimized to turn prop to provide sufficient thrust at hover weight of copter and battery just the right size and weight to be optimal with motor/props chosen.
Probably the smallest motor currently with sufficiently optimal efficiency to accomplish this time goal is the KDE 2814 515KV motor swinging 13" or 14" propellers on a purpose built carbon fiber tube frame.
And those motors alone are $72.00 each.
I am using them on a Hoverthings FLIP Pro FPV Gimbal with extended arms to take the 14" props.
This copter is definitely not optimized for maximum endurance but it is my hope to be able to accomplish near 30 minute practical flight times.
There is one other "trick" that you can use to get longer flight times and that is a straight lithium battery as opposed to LiPos. You can get 30% + more energy out of them per unit weight (but they are very limited as to maximum current output).
18650 is the correct battery designation, but this is very specialized territory.
I am using special enhanced Multistar LiPo batteries which can give about a 20% boost in performance to battery weight ratio.
Currently, the best truly small brushless quadcopter made is the BNF (Bind and Fly) Blade 200 QX (which I also have).
It sells for $230.00 and requires a Spektrum at least 5 channel receiver at around $160.00 for a DX6i.
It can manage 12 to 15 minutes of flight, a bit longer with available over sized batteries.
But third party (Phoenix) carbon fiber airframe is available for it that can accommodate larger batteries while still reducing weight and give you a longer flight time but still not much over 20 minutes.
The propellers are just too small to yield good efficiency at higher weights.
You might be able to use 18650 batteries on the CF frame version that could get around 30 minutes if you can get the max power requirements to work out though.
Basically if you want something approaching an hour you need to add a decimal point to your expected investment and double or triple the size (for now anyway).
Best Regards,
Gary
Thanks Gary,
This is gold.
What you say is not much of a surprise. It seemed to me that since so many quads available no have such short flight times, it must be hard to do.This is precisely WHY I want to do it. ;-) If it was easy, everyone would have done it by now; and in such a case, it wouldn't be worth doing as I could just buy what I wanted.
I have a math and science background, with a lot of computer programming experience, but I am brand new to the realm of robotics in general, and the science involved in developing a good multirotor copter. I have picked up several books that introduce, in an intelligent way, the reader to robotics using Arduino boards. Alas, I have yet to find the corresponding book(s) dealing with how to do the kind of optimization you are talking about. Are you able to recommend a book or three that deals usefully with the science and engineering involved in designing and building a highly optimized multirotor copter? I guess what would be very good is something that documents several projects I could build, based on what I see in the book, and which gives the current main suppliers of parts in Canada and elsewhere. And of course, if there is open source software that can be used to do some or all of the optimization calculations, so much the better (computer code is something I can adapt to my own purposes, once I understand it). Maybe after a few years of studying this (and experimenting as my budget allows), and with the improvements that are inevitable in the technology in this area, my objective may well be feasible: not today, but before I die.
On Amazon.com, the only Multistar LiPo battery is the 3S 5200 mAh for Walkera's Qaudcopter QR X350 Pro. Is that the one you're using? If so, I may be in trouble as amazon.com tells me that it does not ship to Canada. And, Multistar LiPo batteries are completely unknown to amazon.ca.
I DO have a Blade 200QX on it's way (seemingly on a very slow boat from China). I have some questions about it. 1) Will it work properly with the DEVO controllers that Walkera uses for their copters: If so, I should be in good shape as I will have a DEVO 4 and a DEVO 7 by the end of next month (they're coming on a slow boat from China too). 2) I have seen reviews that talk about improved performance for the Blade 200QX by replacing the original propellers by GF5030 propellers. Do you find these reports plausible? The link given showed propellers with 2 blades, but searching I found also GF5030 propellers with 3 blades. Do you have a sense as to whether such propellers would provide a benefit? Am I likely to damage anything by trying the 3 blade propellers the same radius as the 2 blade propellers was reported on? 3) Where can I find a supplier (Canadian, or someone who ships to Canada), for the Phoenix airframe and Multistar batteries you mentioned? What would be the largest battery you'd try for this? Would it be feasible to just get extra spare parts for the Blade 200 QX to build up a second unit around the frame you mentioned (maybe a project for next summer)? If so, can one just put longer arms on that Phoenix frame to accommodate bigger propellers?
Do you have a website where you document your project that you mentioned above, so I can bookmark it and see how your efforts inthis area progress? If so, I'd love to see the URL.
Thanks
Ted
Hi Ted,
On my Quadcopters are Fun Web site there are several pages you should find useful:
http://quadcoptersarefun.com/index.html
Regarding the Blade 200QX I have an introductory page on that all by itself:
http://quadcoptersarefun.com/Blade200QX.html
For basic understanding of quadcopters the following page:
http://quadcoptersarefun.com/Quadcopters.html
And the Build a quadcopter page
http://quadcoptersarefun.com/BuildAQuadcopter.html
You might want to take a particular look at the Quadrysteria Black Mamba frame near the bottom of the above page, it is about the smallest thing that can carry a GoPro and Gimbal effectively and is very well made.
Generally for carrying a GoPro and Gimbal 8" or 9" props are about the smallest I would consider for efficiencies sake and that sets the minimum frame size.
And for more in depth understanding of quadcopter design:
http://quadcoptersarefun.com/QuadcopterDesign.html
Best,
Gary
I am also currently constructing a smaller is better page you might find interesting:
http://quadcoptersarefun.com/SmallerIsBetter.html
Gary
Thanks Gary,
I appreciate all these links.
BTW: My Blade 200 QX finally arrived today. Silly me, I did not order a transmitter for it when I ordered the quad itself, so that is ordered now, and will arrive probably Monday or Tuesday (I found a Canadian supplier, with branches across the country so no Canadian is very far from one of their outlets, which means shipping is inexpensive and fast, in marked contrast to most of the Asian vendors).
BTW: Had you seen this? http://www.rcgroups.com/forums/showthread.php?t=1880665
I wonder to what extent his methods scale down to really tiny size, especially the use of carbon fibre tubes 1 mm outer diameter. I mean he achieved a flight of over two hours. That would be wonderful if it can be scaled down to something the size of the Blade 200QX, or smaller. Can you image that kind of efficiency in Blade's upcoming pico? ;-)
The key is probably the motor, finding one that is designed to be slower, but with greater torque, a matching ESC, and suitable propellers. It is all about ratios of these things against the dimensions of the copter, and it's weight, right? If so, then it reduces to finding a manufacturer that can provide what is needed.
For that matter, what else uses the motors in the Blade 200 QX, and what is the largest propeller (2 blade and 3 blade, or even 4 blade) that that motor, and the ESC used, can handle? It looks to me like there is space for a 5 inch, or even a 5.5 inch propeller would fit without adjacent propellers hitting each other. That should greatly improve efficiency over the 4 inch propellers it comes with, right? But I do not want to burn out the motors or ESC on my first Blade 200 QX.
Cheers
Ted
Ah End of Days - been there done that.
It is actually possible to build an endurance copter with those cheap components, lots of people have done it and I have a set of those cheap RC Timer motors myself.
However, it is NOT a practical quadcopter, it handles very poorly, is very failure prone and is mostly good for hovering quietly in a very wind sheltered area for a relatively long period of time.
It is an experiment with cheap parts on a setup optimized for one thing only - holding its own self aloft in a static hover for the longest period of time.
These particular RC Timer motors are very low quality and often arrive barely or not functional and they have short service lives.
They are cheap junk really.
I have been there.
To get into the practical aspect of long endurance copters you really cannot also be about cost cutting at the same time, one or the other, not both.
A practical long endurance copter that is actually designed to fly around and do something is not the same as a record attempt copter that is only designed to move minimally while hovering quietly above the ground.
Even though my current writing is about the necessity and benefit of very small quadcopters, the fact remains that the biggest propellers spinning at the slowest speed are the most efficient - always - period.
However they also have a downside, increasing dynamic instability (especially on quadcopters) and slowness of response.
For taking videos or photos, the dynamic instability can definitely become problematic and even for basic control in gusty winds.
And the slowness of response can make the copters sluggish.
Basically a practical balance always needs to be struck.
When I started I was attracted by all the cheap parts available, now I am attracted to the best parts for the job.
In motors for instance, KDE multirotor motors generally have 3 ball bearing races with at least one larger bearing which supports the lions share of the axial load.
They are also the most efficient motors available, which is critical for the longest (practical) flight times.
Their motors are optimized both for efficiency and longevity and the motor is the core ingredient of any multicopter system.
The bottom line is if you want a practical quadcopter with exceptional longevity you really have to use the best components and that also generally means the most expensive.
This is my current main quadcopter, a Hoverthings Flip FPV Pro G with extended frame arms, KDE 2814 515KV motors, 14" props (13 are generally better for this copter), a Quattro 4 in 1 ESC and a Pixhawk flight controller with a Sony AS100V sport camera.
This represents the best components I can buy, it gets around a safe 25 minute flight time the way it is configured with the optimized low C Multistar 6600MAH LiPo battery.
Best Regards,
Gary
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