I have been searching high and low for a good affordable large hexa system, with the main objective to lift 500gr (camera, FPV transmitter, etc) for as long as possible, and have the video stabilized.
The S800 looked ok, but due to some issues around the boom flexibility and cost, I ditched that idea. The Carbon Core, Steadidrone H6X also looked very nice, but once again cost played a big role.
So, I stumbled across the Tarot T810, for $330 I got the frame. I needed to add some extras for folding landing gear (not retract) and the camera rail mount which was not included.
I'm doing a build log to not only "hopefully" help someone out there, but also have a place to get some input from the community in getting the max flight time. The Hexa will be used for local security missions and possibly also help in the Rhino Poaching crises we're facing in South Africa.
My system:
- Tarot T810 Frame
- Sunnysky 4112S 400kv
- 40 Turnigy Plush
- 15X4.7" props
- APM (of course!) - Looking forward to a maiden flight on AC3rc6
- Martinez gimbal controller
- Brushless Gimbal
- Gens Ace 6S 5500Mah X 2
- Estimated AUW including gimbal and camera - 5.3kg
The frame went together nicely, only issue I had was the hole in one of the landing gear braces was skew, I just drilled it straight with a bigger drill bit.
Here is a view of the frame in it's folded position. It folds nice and small - about 900mm in length
Here are the motors I'm planning to use, hopefully I get my flight time. Powerrrr! Notice the ESC mounting plates under the motor mount.
I like the prop attachment.
I also like the way the booms lock in place with a dovetail clamp, very secure.
Here is a shot of the little power distribution "lugs" - I just soldered all the power wires in place with huge amounts of solder.
I'm planning to install the ESC's under the motors, I have read about some scare stories on RCGroups about this idea, but I have never personally had problems with this.
I am however a little concerned about the wire gauge for power - using 16AWG to the motors and 12AWG to the battery. I'll do a full power test to see if they heat up, and by how much.
I'm wating for my ESC's to arrive, and will continue the log once they're here!
Comments
That's cool man Thanks,
As you were saying I could just use that resister adapter as a start up. Plug the battery into that resister adapter into the MR with battery and then plug the second battery in normally. After unplug the resister adapter and plug the first battery in as normal without the resister adapter to avoid sparks & spikes.
Right??
Thank you Thomas for the great info.
Interesting the difference in size between 5W (on the right) and 3W (on the left). I'm skeptical about the 5W rating - it seems likely that it could take a lot more. Anyway, you don't have to go with these silicon resistors. Any cheap resistor will work, but some are more easily broken (ceramic).
Yes, no bother. This is my "no spark" pre-charge adapter, quick and dirty but sturdy enough. The solution doesn't need to be like this - lots of options including on-board with a separate set of small leads. The wire doesn't need to be heavy like the 10-gauge I used. The most current it would carry on 6s is 25V / 10ohm = 2.5A, and steady-state current in my case is 0.5A. Here is the 5W resistor I used ($1.49):
http://www.digikey.com/product-detail/en/RS00510R00FE73/RSC-10RCT-N...
If I put this on-board, I might go with a 3W instead of 5W, since the 3-watt size is much smaller.
http://www.digikey.com/product-detail/en/RS02B10R00FE70/RSB-10RCT-N...
Just make sure heat can ventilate in case the resistor is left engaged by mistake - 3W will eventually get really hot. But for a 30-second start-up and no gimbal loads, the 3W is probably fine. For heavier loads, a 5-ohm or even smaller would be a better choice.
@Thomas Field,
This is great, thanks for all the detail. I hope it's not too much bother, could you show us some images? I'm kind of a visual learner and I'm having trouble imaging what you've done. Could you send some links to the resisters you used. This sounds like great info to further protect against crashes.
Hope it's not too much bother.
Yes, the arc illustrates very high current rushing in to "instantly" charge up all the ESC and BEC capacitors. The current could start off at hundreds of amps - limited only by the capacitors' internal equivalent series resistance (ESR), the wiring resistance, and the battery source resistance (very low).
That arc will eat away your connectors eventually, starting with the thin gold plating. The extreme inrush current can also be hard on capacitors, especially the low-grade electrolytic caps used on ESCs. Abuse shortens their lifespan and gradually degrades the effectiveness.
To avoid this, I pre-charge the aircraft's DC power bus using a simple adapter with in-line 10-ohm 5-watt power resistor. Other low resistor values would also work. The 5W resistor barely gets warm even if left in place, carrying about 0.5A. The bus voltage goes up to about 20VDC in my case (NAZA and RX drain plus ESC idle current), but if you have gimbal motors or other loads you could see higher current (consider using a smaller resistance).
After the pre-charge, I connect the second battery pack which brings the bus up to 25VDC without a noticeable spark (probably a tiny one is there). Finally I remove the resistor adapter and connect the first battery pack straight through. This procedure adds a few seconds to each power up, but does avoid the Big Spark. Sometimes I leave the resistor adapter attached to a spare 6s pack and use that for each pre-charge.
For single-pack harnesses or convenience, you could make the inrush resistor a permanent part of the on board harness. I might do that "next time" since the silicon power resistor is lightweight. After the pre-charge inrush is over, bypass the resistor with a wire jumper made of insulated bullet connectors rated to carry the full load current. Make sure the bypass plugs can't short to carbon or metal parts when loose! In theory you could bypass the resistor with a beefy toggle switch, but watch the switch DC current rating. A switch rated to disconnect 100+ amps at DC is likely too big and heavy.
@Stubugs,
I think I know what you are saying. Are you referring to using capacitors? I ask because my NASA also thinks that I'm at a lower voltage, but my capacity is just fine. I can't figure out why my voltage looks so low when my capacity is just fine. I've also noticed a big spark to as well, but I thought that was just because I'm using 6S. ARe you saying that these issues are due to using capacitors?
Because of the initial load tried putting a resistor on a small lead from battery first but even a pot heavy duty resistor got that hot that it melted the heat shrink
And naza thinks battery is low voltage
So now I have 4mm male and female plug and touch the end first for the flash then slide it in at least the connector don't join on the burnt bit
Stu
Nice.
I put my caps inside the booms at the halfway mark between the the battery and the ESC. I'm only using one cap per ESC though.
Your setup looks good.
Yes I read up quite a bit on using extra capacitors
And thought bes be safe that sorry
Stu
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