Hey guys, my group is interested in using a multirotor aircraft for near surface remote sensing (earth science applications). We'd like to have the most flexible and versatile platform. For us, this means high payload capacity, reliability, and versatility with respect to configuration. The ArduCopter stuff is particularly appealing to us as it offers the greatest flexibility for mission planning, development, etc.
We are interested in building a CineStar 8 but using ArduCopter electronics (APM 2.5). From my forum searches I see that many people have done similar things, so I know this should be possible.
I'd appreciate some guidance on several things (my background is not in RC electronics):
* What motor/prop/ESC/lipo configurations will give us the best payload capacity/flight time balance? I've used the eCalc online tool, but most of this goes way over my head (I know that I will need to grasp it fully before we continue, but I don't know where to start!)
* How to expand the APM 2.5 outputs so that all 8 motors can be controlled in addition to stabilizing a camera gimbal? Is there another way to stabilize/control the gimbal without expanding the outputs?
* Assuming that we have an airframe, is my checklist here close to complete for the whole build?
And for adding on a controllable 3-axis gimbal
The ESCs are a particular mystery to me. I played around with the eCalc tool and couldn't figure out the proper ESC to use for the AXI 2828/12 motors (for example). I kept getting errors indicating that the max current was greater than the battery could supply. So, any additional information on how to select batteries/motors/ESCs would be very much appreciated (including just pointing me to the relevant literature).
One more question: Can the gimbal/shutter controls be integrated into a flight plan from the Mission Planner? It appears that they can, but I don't know what is involved to get that capability.
Thanks in advance!
I will try to help:
1. Propellers - APC 14x4.7 SF, you need 4 pusher and 4 regular
2. ESCs - Any 60A opto, like hobbywing
3. Motors - AXI 2826/12 or equivalent. I have some used ones available here: www.rcgroups.com/forums/showthread.php?t=1808801 Please note you would have to change out the regular length shafts for the short shafts that are included. I also include the radial propeller mounts.
4. Batteries - Either 4S or 5S. I fly 4S
5. I believe the APM 2.5 supports 8 motors and stabilized gimbal without modification
6. Radio - I use a Spektrum DX8 but Graupner makes good stuff too.
7. These guys make good power distribution boards for large octos: Power Hungry Systems
8. 3-axis gimbal might be overkill.. depends on what you are looking to do. You can also just use the yaw of the copter with a 2x. Probably not as smooth of video though.
Hope that helps!
Wow, that's great information, Adam.
Any input on how motor/prop/battery pairings influence flight time and payload?
Is there a reason other than aesthetics to use a power dist. board instead of the "Deans rings" some users have made? The Power Hungry systems solution looks nice, but it's $275 and I just want to know if that's worth it.
I recommend using bus bolts, it's a tried and true method of power distribution, and it makes future repairs and component changes easy without the risk of loose connectors, plus it makes a tidier circuit path. You want all the circuits to originate at the same point if possible. The prices being charged for PDBs are ridiculous.
It depends on how much weight you need to carry. You can see an apples to apples comparison here of amps drawn and ESC temps: http://vimeo.com/42225781
The Power Hungry Systems have tested their ring extensively, so there is a bit of peace of mind there. There isn't really a problem with making your own. It will essentially be the same thing - copper ring with power connections.
Josh, you also have to take into account the pilot. ;)
Half the questions in your list hint that there's not a single guy with multicopter experience in your group. While the APMs are potent flight controllers, they don't have an error forgiveness variable that you can dial down as you gain experience. And as I'm looking at a $3000+ wish-list, your first mistake might be a costly one :)
You'll need at least two more machines before you can safely operate the Cinestar8:
- One very small and cheap quad, maybe a WLToys v929/939, with lots of spare props and parts. Once you can fly that miniature thinghie for a couple of minutes with it's front facing you, you're OK for the Cinestar :)
- One diydrones quadcopter with the FC that you'll use on the bigger octo, to learn tuning, P/I/D values, connections and general operating procedures. Also the do's and dont's at way lower expenses.
Either that, or hire a seasoned drone pilot.
Thanks for the reply and perspective, Para. Please don't take my admitted ignorance of the topic to represent the knowledge base of our working group. I am essentially on a fact finding mission to figure out what it would take to construct and operate a beast of this size. I fully anticipate that we will make numerous mistakes and I realize how costly they may be.
To that end, we've definitely planned on following your suggested pathway. First, we intend to source a small Blade qMX (or like) trainer as our first step. We collaborate with a lab that is already flying a smaller ArduCopter sourced from jDrones, so we'll benefit from that experience the entire way. There's also another researcher in an aligned discipline who just received a RTF CineStar 6 w/ MK controls. Within a larger working group we can leverage the experience of colleagues who even more experience flying fixed wing and multirotor aircraft in earth science applications.
Since our primary objective is to develop the earth science sensing capabilities of UAVs, we would like to have a platform which can accommodate large sensing payloads such as lidar scanners, hyperspectral cameras, etc. We fully appreciate that safely operating such an aircraft will require a progression of skills development.
That's a good point. You don't want your first mistakes on this expensive of a platform.
Hey guys. I appreciate your input before, so I'm asking for a little help again.
We've decided that we're going to buy the following package:
I think that will be a nice progression because the Quad will have nearly identical electronics to the CineStar 8, and will allow us to learn how to configure and use the APM before stepping up to the bigger platform.
I've been putting together a parts list, and I decided that I should probably make an electronics diagram so I could ensure I can put it together and that I have all the required cables. I hope that you guys will take a look and tell me what I've done wrong (picture below).
I have a few questions regarding the setup:
I think that's all the questions for now. Please take a look and share your wisdom.
The output on the APM's PM is only 2.25A, correct? You will need to bypass the the PM with the power supply to the PD so that motor power is not drawn through the PM.
Thanks, Al, you're the first person to mention anything about that. My understanding was that the 2.25A was to the APM, and that the full current is able to pass through the PM. I cannot find any information specifying that the PM should not be used to power the motors. If it were bypassed to go to the PD, the only current draw measurements available would be the APM draw, right? Since that's trivial, we are really concerned with knowing the motor/ESC draw. What have I missed? Thanks again, Josh.
No, you have it right. Sorry for the misdirection.