Anatomy of a 301 km Flight

Today I flew my Cyclops EPO for an incredible 7 hours and 8 minutes, covering 301 km (301 km !!!) in one flight.

After flying my Maja for 126km I decided 200km would be my next challenge. I got the Cyclops with that in mind, it was very very efficient straight out of the box and after my first flight test I realised it was capable of much more.

I did 5 flight testing sessions where I tested different speeds, C of G positions and propellers. The data from my last two sessions suggested 300km was possible with good conditions so that became my goal.

I planned my mission with a couple of waypoint path options that I could switch between using do_jump. After a hand launch I switched to auto for a very gentle climb reaching 50m of altitude over about 2km. I flew a few laps of a 2.5km lap, before switching to a 3km lap and then a 3.5km one which used a do_jump command to fly continuous laps at 60m altitude.

To monitor my progress I’d made battery consumption schedules for 250, 280 and 300 km. My calculations said that I would need to run my batteries down to 10% remaining to reach 300 km. The first half of the flight was very calm and I was ahead of schedule. But the wind picked up in the afternoon and it became apparent that I might finish with less than 10%. I tried to help the situation in the last hour by varying my speed around the lap. I flew at 14 m/s for the head and cross wind sections, and dropped to 13 m/s when I had a tail wind. I hadn't done any calculations to support that, it just seemed that I could make the most of the tailwind section by dropping my power there a little.

I’d decided in advance to end the flight when the battery dropped to 12 V (3.0 V per cell) and I could see as I passed the 280 km and 290 km milestones that it really was going to be tight. The voltage was hovering either side of 12 V as I approached the 300 km mark so I knew it was time to bring it in, but I also knew that Mission Planner can underestimate the distance compared to the GPS log. I decided to fly to 303 km to be safe. The way the laps worked out it was 305 km when I hit the ground, and just as well because the GPS log came up as 301 km. If I’d come in when Mission Planner told me 303 I would have been member of the 299 club.


The telemetry log file is 47 MB (linked below) and Mission Planner crashed when I tried to create the KML file (I tried on three different machines). It did manage the GPX file thankfully.
Key specs:

  • Cyclops E with V-tail
  • APM 2.5
  • Panasonic 18650B Li Ion batteries. 4S7P, 23,800 mAh
  • Aeronaut 11x9 prop
  • Hobbyking telemetry
  • Distance covered: 301km (according to GPS log file, 305 km according to Mission Planner)
  • Flight duration: 7 hr 8 min 10 sec
  • Average groundspeed 41.7 km/hr

Log File (47MB)

E-mail me when people leave their comments –

You need to be a member of diydrones to add comments!

Join diydrones


  • There were 24 batteries in a 4S7P configuration making a total of 23,800 mAh.

    Is that a typo? Do you mean 28 cells?



  • 300km

    @ Mustafa TULU - No it's a Commercial Off-The-Shelf (COTS) battery. They are Panasonic 18650B Li Ion batteries that I bought on ebay for about $10 each, the batteries were the most expensive part of the setup. There were 24 batteries in a 4S7P configuration making a total of 23,800 mAh. The batteries weigh 47 g each, and I put them in a plastic holder which I drilled holes through to lighten further.

    (I'd have loved to have them welded but I couldn't find anyone locally to do that)

    @ vova reznik - sorry I missed that from my list. It's a Hacker A30 52S UAV 

    @ wayne garris - yes you're right it is a very very efficient airframe. Kudos.

    @ Ted Van Slyck - good question. I took a book and a chair. When I did my Maja 126km flight I read most of George Orwell's 1984 checking on the flight every other page to monitor the flight. But this time I had company for almost all of the flight. Thanks Steve and Rudy. They did the aerial filming, and had a lot of fun chasing each other too as you can see from this pic.

    I don't know if you know the game cricket, but it was a lot like watching a good cricket match. It ticks over all day and think you know how it's going to progress but as it gets closer to the end the excitement builds as it comes down to the wire.


    @ Gary McCray - I don't know. I think R. Montiel's massive 100km return flight was very impressive, more impressive than mine as he flew 100km away from himself. That's 200 km as the crow flies, but I think his total distance covered was about 250 km. He used a glider with solar cells and relied on thermals for lift.

    @ Gary Mortimer - thanks.

    @ BacklashRC - hear hear

    @ Antonie Kruger - I had a car cigarette lighter adapter for it, and I had the car engine running much of the time. I actually drained the car battery to the point that I couldn't start the engine when I tried the first time after about an hour. That could have ended the mission but fortunately I had some jumper leads.

    @ wayne garris - yes there is more to be squeezed out of it. I got about 41.5 W for the first half at 13 m/s 45 W once I shifted to 14 m/s. I haven't been able to open the whole file in excel (it is 300 MB). I get an error message saying the whole file can't be opened. I can see the last hour and a half is missing.

    My last day of testing was for flying with 8P4S. I didn't have enough batteries so I used 7P4S plus some ballast. It handled the weight well and the data said I would hit about 325km. I ordered 4 more batteries and planned to do the attempt with 8P4S but they didn't arrive in time.

    @ Reto Buettner - thanks that's high praise. And thanks again for all your help with the drive chain selection.

    You're right about the susceptibility to wind. My testing showed the best speed was 13 m/s so I relied on a calm day. I was ahead of my schedule in the morning when it was calm but the wind came up a little in the afternoon (to 10 - 20km/hr) and it knocked me back, I only just made the 300km mark.

    @ Tommy Larsen - Hacker A30 52S UAV 

    @ Ted Van Slyck - that's exactly how I tested my setup. Flying laps with different settings and using the record of the airspeed and current in the telemetry log to find out which was most efficient.

    @ Justin Martin - I like your idea, but the problem would be how to standardize a useable payload so you can compare achievements.

    My calculations say that I could do 223km with a NEX5 and roll gimbal (assuming the camera and gimbal weigh 400g together and I could mount it in the fuselage without upsetting C of G). It would mean dropping 2S4P of batteries but keeping the AUW about the same.

  • Wow! I love your work! It's posts like yours that keeps me coming back to DIY Drones. Thank you. 

  • Moderator

    Are you offering to hand in your badge Reto? (;

  • I love that you were able to just let it go and then chase it around. oh and doing the do_jump's for the different size rings was a great idea. Well done!

  • T3
    Assuming the pack went to 0% that .86 km perwatt/hr. That's really good. It would be cool to have an efficiency challenge, so its about more than total capacity. The more batteries you add, the smaller that number will be. My guess is that if moglos cut about a pound from the planethee efficiency would go up about 25%.

    With a pitot tube and ammeter we could find best range speed too, that would be cool.
  • This is fantastic!! What engine did you use?? :)

  • 100KM

    Congratulations Moglos!

    Over 300km and over 7 hours is a great achievement. I am in awe. Even more knowing you have neither a university nor a aviation company backing you, but just you doing this in your spare time for fun with COTS components.

    The only weak point might be the slow flight speed, making such flights susceptible to wind. But I don't want to narrow your great accomplishment.

    300km being the new benchmark, 100km hardly seems worth a badge anymore ...

  • 100KM


     Nice flight, it would be interwsting to squeeze even more out of it. I was reviewing your log files. interesting, the average wattage is about 45 watts. At least that's what i can see from the replay. I am converting to CSV but still waiting on it to convert. is that what you would estimate?

  • Moderator
This reply was deleted.