Idea for longer flight FPV

[Kilby]

Hey guys, I wanted to bounce an idea off the group that has been jumping around my head for the last few weeks. I'm going to do a new FPV build this winter, but I really wanted to build something that gets much longer battery life then what I'm used to. Watching the DJI S800 on the AP side of things got me thinking about a new type of FPV set up. In short, I was wondering what performance would be like if I built a TBS discovery with longer arms that hold a motor/battery/prop config more like the S800. 6S battery, lower kv motors and 15 inch props on a small light weight (in comparison) FPV craft.

I've tried running some numbers through eCalc, but I'm not 100% sure i've got everything accounted for. From what I'm seeing, it could be a flight time of around 30-35 minutes. Does anyone else want to try running some numbers and see if i'm right? I'm sure there has to be a proper set up here somewhere, and how cool would it be to get 30 minute FPV flights on a quad?



-Terry

 

[Maarten_NL]

Can you show a screenshot of the eCalc, I'm very interested in your view.

 

[FerdinandK]

Hello Terry,

This copter is able to do so:

It is using the NX 4006 530KV Hobbyking motors, 14x8 props, hobbywing 18A ESCs, Naza and the Horizon HD cam. Here the flight-time is arround 30min with one 4S8000er Zippy (more with a maxamps.com 4S11000).

here a video:

The key is, that your frame is as lightweight as possible, my frame had about 120gr.

best regards

Ferdinand

 

[DennyR]

I think a tricopter would be even more efficient running 15" props.
Something like a Turnigy Talon.

 

[Kilby]

Thanks, FerdinandK, for helping to confirm my theory. I wonder, does your set up work with a 6s battery? If you are able to get flight time like that from a 4s, I wonder how a 6s would work?

-Terry

 

[FerdinandK]

For a 6S setup you need (good) motors with less KV compared to a 4S setup. The enery you take with you is determined by the mass of the battery (whatever voltage it has) you only cut down the current, but you have to pay for this in the motor-windings.

I have this 6S hexa based on the rc-timer 360KV motors with 15x7 props, which runs also for quite some time (more than 40min in hover):

but the Graupner propellers are better for flying.

best regards

Ferdinand

 

[Kilby]

FerdinandK, what do you think of those motors? I was checking them out last night. The price is great, but that always makes me wonder about the quality. Would you recommend them?