Maiden Flight of Stephen's Long Endurance Hexa Design

Hi folks,

this is my first post here. I was looking for some UAV for mapping and same as Gerard Toonstra came across Stephen Gienow's great "concept design for a long endurance hexa".

And here it is!

I'll post more details within the next weeks.
Here is a video of the maiden flight(s) of this configuration under windy conditions:

Thanks a lot to Stephen for posting this setup and for his help!

Thorsten

Views: 1535

Comment by Erle Ellis on August 28, 2013 at 1:00pm

Sweet!

Comment by Stephen Gienow on August 28, 2013 at 4:52pm

Very cool!  It is great to see my concept for this particular copter come to life like this.  Now I just can't wait for the endurance tests.

Comment by Erle Ellis on August 28, 2013 at 4:56pm

I can't wait either!  

Comment by Thorsten on August 29, 2013 at 7:30am

Results of the first endurance test with:

  • 2 x 6500mAh 4S batteries
  • 3.11kg all-up weight (including camera)
  • loiter (some stabilize)
  • 22% battery power (amps) left

Flight time: 30 min

30min is ok for me for now and there is potential to reduce the weight by about 200-250g. Compared to Steve Westerfields numbers (2 * 6000mAh, 2.8kg and 42min) my hexa is about 11% heavier but has about 8% more battery power. So in total it is about 3% (if this calculation ic correct) less efficient but provides only 70% of the endurance. Any idea?

Comment by Thorsten on August 29, 2013 at 7:57am

Stephen, I just saw you let the battery run down to 13%. When I plugged the batteries to the charger it reported 14.78 V. Sounds a little to high - or?

Comment by Stephen Gienow on August 29, 2013 at 8:18am

Thorsten-

The voltage you saw on the lipo charger was the voltage at rest.  The important voltage is the voltage under load.  You can see this via a telemetry uplink using mission planner while the copter is in the air.  

Using 80% of the battery is one practice, but I've found it a bit restrictive.  Instead, I use the rule of thumb that the lipo cells should never drop below 3V each, under load.  My answer used to be that the ESC would cut off before voltage drops low enough to damage the lipo, but I looked it up and SImonK firmware has no low voltage cutoff.  In that case, you have to simply monitor the voltage and land before it reaches 13V.  13V still divides out to 3.25V per cell, but it is getting dangerously close to 3V and the voltage drops faster on the low end of the cycle.  So I always plan my flights to land right before hitting 13.00V.  Be conservative for this, because in those low voltages the voltage can really drop when you're not looking.

Comment by Stephen Gienow on August 29, 2013 at 8:25am

I did some further research and most ESC cutoffs kick in at 3.2V per cell, or 12.8V.  That would seem to square with my method, since landing by 13V has ensured that my ESC cutoffs never kick in.

So my recommendation to you is watch the voltage on the telemetry uplink (you have the 3DR power module for monitoring voltage and current, right?) and land before you hit 13.00V.

Comment by Stephen Gienow on August 29, 2013 at 8:30am

ANd I'll add one more comment because I cannot stress this enough: the 13V limit is the voltage under load, while the copter is flying.  This is not the same as when you check the voltage using the charger or a multimeter.

Comment by Erle Ellis on August 29, 2013 at 8:51am

So am I correct in assessing that this rig can now do a 30 min image acquisition mission?  Or is this still in progress?

Comment by Stephen Gienow on August 29, 2013 at 9:06am

From what Thorsten has posted: yes.  Further testing may reveal a longer endurance.  I don't think he has taken it on waypoints yet though.

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