It's official.  Guinness World Records validated the flight (see link under Flight 1).

Two flights were achieved to demonstrate that multi-rotor aircraft can stay in the air carrying a payload for a long period of time.  While 20 minute flights were considered long in 2014, these demonstration flights show that 1 hour flights can be the norm.  Imagine the increase in commercial applications when it is common for ships to stay in the air for an hour or more carrying different payloads.  It's just a matter of finding good rotors (Tiger), flight control electronics (3DR), batteries (Panasonic Li-Ion), ESCs, and removing unnecessary weight.  Once industry realizes the importance of performance, we will also see a jump in rotor and ESC net-lift efficiency (lift after it gets itself off the ground first).

Flight 1 – Guinness World Record for Longest Electric RC Multicopter Flight (Duration). Pending Guinness review.

  • Ship Name, Rufous
  • A hover that stays within view of the stationary video camera
  • 1 ½ hrs (97 minutes 23 seconds) on 8/21/2014 @ about 4 meters above open level ground (well above ground effect and without use of thermals or updrafts)
  • Hover, while not impressive nor useful, does require more energy than typical flight speeds and as such, a good first test.
  • Pixhawk Flight Log (Time, GPS, Altitude, Speed, Volts, Amps): Guinness Flight
  • Video of the Guinness record
  • Guinness Record Book

  • Time Lapse (GoPro) of the Guinness record.

  • Ship Secrets

Earth view of the hover breaking the world record.


The officials:  Michael Allen (expert in UAV flight control; Cloud Cap Technology), Brett Faike (UAV extraordinaire; teaches UAV tech at local schools; gave FPV demo after flight), Forrest (pilot in training), and Kirby Neumann-Rae (editor of the Hood River News).


Celebrating surpassing the old record of 80 minutes (ahhh ... hey pilot ... a little less champagne and eyes on the copter ... it's not time to prune the orchard yet!).  Bud, not shown, was taking photos.  Hope you got some champagne Bud!


Co-pilot, Dr Carie Frantz ... yes this amazing looking lass is single, is an unreal outdoor bad-ass, and has a great job in case you were wondering.  Thanks for keeping pops sane Carie.


Posting the final time (for the final application to Guinness, I requested that 4 seconds be taken off because some blades of grass were brushed prior to the ship finally giving up and setting down.  An interesting note on the battery:

o The Li-Ion batteries used are rechargeable (flight was on about the 8th recharge).

o Running Li-Ion batteries down to where the ship drops out of the sky does not hurt them if the ship mass and battery voltage is engineered to invoke that event before voltage runs down too low.

o A few days later, Flight 2 was made using the same battery pack with the ship carrying a camera (see Flight 2 next).

o Li-Ion are low C discharge (not 30 or 20 or 10 ... think about 1 C).  The chemical barrier will break down if amp draw is too high. This causes the ship to loose altitude.  And if there isn't enough altitude for the battery to recover, crash. As an example, using a 4S5P battery pack (about 15000mAh), Rufous hovers and flies at moderate speed at about 8 to 10 amps depending on payload and flight demand and does great even in moderate winds. Rufous has even flown 60 mph (97 kph) on the same Li-Ion battery pack. However, get up to 15+ amps turning a sharp high-speed corner and the battery chemical barrier locks up in about 2 seconds (yes I've had to rebuild a few times before I figured this out).  So caution.  Do the calculations.  Try to design a safe ship that stays in the air at 2x the amp usage at hover. 


Flight 2 – Performance demonstration flight (actual flight versus stationary while carrying a payloads)

  • Time aloft                                                                 goal of 1 ½ hr; so far 82.9 minutes
  • Distance traveled                                                       goal of 10 km; so far 14.4km (9 miles)
  • Elevation gain (cumulative)                                        goal 300 meters; so far 378 m (1242 ft)
  • Speed           (max)                                                   goal 18 m/s (40 mph); so far 9 m/s (20 mph)
  • Speed           (typical)                                                 so far 2.3 m/s (5 mph)
  • Payloads                                                                  GoPro Hero 3+ and 3DR Telemetry Module
  • Flight Log  (Time, GPS, Altitude, Speed, Volts, Amps)  Performance Flight
  • Video                                                                        coming soon

[note:  will try to beat 90 minutes carrying a camera when I get back from Sri Lanka]

Earth View showing the flight path of the performance demonstration over my orchard.

3689612811?profile=originalPhoto taken by Brett Faike, a local multi-copter flying legend, of the flight area (man-cave on left and princess palace on right).  He treated the witnesses of the Guinness record to FPV flights afterwards using two sets of goggles so we could "ride" along (keeping the ship within visual range and over my farm, of course).


Flight #2 (with camera and telemetry payloads), Elevation Profile.


Flight #2 (with camera and telemetry payloads), Watt Profile.


Flight #2 (with camera and telemetry payloads), Speed Profile.  The wind speeds were about 2 - 4 m/s from the north..


Flight Team

  • Design/Engineering                                 Forrest Frantz
  • EE/Flight Engineering                              Jim Frantz
  • Test                                                       Marty Frantz
  • Pilot                                                       Forrest Frantz
  • Copilot                                                   Carie Frantz


Acting Guinness Judges/Timers

  • KirbyKeumann-Rea             Hood River News                       Editor
  • Michael Allen                     Cloud Cap Technologies             Flight Control Software
  • Brett Faike                         Multi-Rotor Extraordinaire           Software Developer


Ship Summary:                                                                                1.65 kg (w/ camera & telemetry)

  • Frame                       Quad Carbon tube w/ open front for photography             62 g
  • Flight Controller         3DR Pixhawk + 3DR Power Module                               34 g
  • Motors                      T-Motor MN3508-29 380KV                                         328 g
  • Propellers                  T-Motor Carbon 16 x 5.4                                             116 g
  • ESC                          Afro 20A                                                                     31 g
  • Batteries                   Rechargeable Panasonic NCR18650B 4S5P                 930 g
  • Camera                    GoPRo Hero 3+                                                            76 g
  • Telemetry                 3DR Radio V2                                                               19 g
  • Wires & Misc           Long wires runs were magnetic wire                                54 g


Design Elements of Note

  • The electronics platform (EP) was eliminated to save weight (previous EP added 8 grams).  The battery doubled as the EP.  The flight controller (FC) was bonded directly to the battery, which was bonded directly to the frame.  The battery has a strong electro-magnetic field around it.  3DR deals with this issue by putting the sensitive elements, the GPS antenna and Magnometer, separate so it can be placed away from the battery.  In this case the GPS/Compass was bonded to the starboard-fore motor arm away from the battery.  This is a testimony to the excellent design of the FC as it did its job that close to a large battery.  Even though this worked, it is not recommended nor fully tested.
  • The ESC have their heat sinks removed.  To ensure cooling, the ESCs were placed directly under the tips of the propellers to get positive prop wash.  The loss in lift is much lower than the loss in weight.  To help protect from shorts, spray the ESC with electrical silicone.
  • Wiring in right sized.  The normal EE rule of 3% tolerated loss is put aside.  The rule is replaced by physics of electrical transmission.  A larger wire area cross-section  produces less heat that is measurable in watts.  And a larger wire area cross-section weighs more thus taking more watts to lift it.  Thus watt usage can be calculated for all wire sizes and thus optimized.  Some wire insulation is weak or can break down in sunlight.  Magnetic wire was used where possible.  But multi-wire strands are recommended to prevent wire breakage due to stress aging.
  • Li-Ion batteries are about 50% more efficient (watts hours/gram) than LiPo for multi-rotor flight.
  • Metal screws/nuts/washers replaced with nylon.  The only exception are the propeller screws which are aluminum.
  • Metal screws/nuts/washers and clamps replaced by bonded parts.
  • Gussets, screws/nuts/washers, and plates replaced by continuous masts and bonding.
  • Metal spacers replaced by short nylon spacers.
  • The most efficient propellers and motors were used – Tiger T-Motor.
  • Props and motors statically and then dynamically balanced.



Ship Performance:

  • Vibration Average Score               0.05 gs.
  • Stability Score:                            0.14 degrees.
  • Photography                                see test photos



Photo taken from tripod (baseline) with GoPro Hero 3+ at med 7m.


Photo taken from Rufous.  The camera was hard mounted, so now need to work on camera isolation that works.


Test Flight Highlights:  Prior to “Flight 1” the ship crashed three times. 

Crash 1 – Tried saving 2 grams by using Single Ply Carbon Skin Nomex core sandwich panels for motor mounts.  The Nomex core on one motor sheared causing a cascading event where all of the motors sheared.  Picture the ship moving away in an uncontrolled fashion with one motor suddenly floating away and quickly followed by the other three motors as the frame and battery kept flying in a deep descent.

Crash 2 – Really stupid piloting.  I cut power after a landing but forgot to disengage the motors (throttle lower left).  As I bent over the ship, my belly pressed the throttle to full and I got a face full.  Luckily wearing protective goggles and thick clothing.  Sometimes it takes a hard lesson to learn – always disengage the motors and the first thing one does when approaching the ship is to push the red button on the Pixhawk. 

Crash 3 – Had been suspicious of one motor mount bond (didn’t sand all surfaces on all the mounts).  The suspicions came true as one motor left the motor mast and the ship impaled itself into the lawn (photo below) after some high speed runs that loosened the faulty bond.  This crash broke one of the motor masts.  The motors are held on with nylon screws that are sized to shear off without harming the frame.  This works most of the time, but not this time.


Anyone interested in beating this record (the 100 minutes mark is itching to be broken), friend me and I'll gladly pass along what you need to do to satisfy Guinness.  I only ask that we are gentlemen and set records using engineering and piloting skill minimizing the use of ground lift (e.g., please avoid a hover off of a hot tar roof above a heated wall or on a side of a hill/ridge or in ground effect).  We want to show industry what is possible under normal flight conditions.  I also ask that you fully disclose your ship so we can all learn from what you achieved.  Thanks.

If you have any engineering questions, I'll will answer them below.

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  • MR60

    Agreed.  I'm flying it with a camera now.  Will hopefully post the results before going to Sri Lanka.  

  • Congrats!  
    Do you have the schematics on how your built the Li-Ion battery?

  • Congrats... Now get this flight time with a usable payload....

  • MR60

    Comments on other duration videos.  Some of you will or have seen videos of ships flying longer than 1 1/2 hours.  No matter how these flights are accomplished, try to take away what you can in knowledge from their flights.  But also ask, were lift effects used to extend the flight? I've personally contacted all of these flyers to ask them to repeat their flight on open level ground to:

    - Minimize use of ground effect (flying close to the ground).

    - Minimize use of thermal and hill lift effect (e.g., flying above the wall of a heated building over a tar roof).

    Rufous (the above multicopter), for example, has done several flights of over 1 1/2 hours in wind and calm without the need of wind lift.  It doesn't take long to repeat flights in a manner meaningful to industry.

    I'd like to suggest that we move forward using engineering and design to break the next barriers and do so over open level ground:

    - 100 minutes and then

    - 2 hours.

    The goal is to demonstrate to industry that long flight times are possible (and necessary) in normal flight conditions.  If someone wants to try to break those next two barriers, friend me.  I'll gladly help and share what I know.

  • MR60

    Thanks for all of the support and interest.

    • Yes, a flying battery is an appropriate description.  This is definitely a minimalist design.
    • PID - Haven't done a lot with PID research in regard to flight time.  Do lower settings help?  I don't know how much.  Settings for Rufous were typical. All setting can be found in the log file that is attached in the blog.
    • Li-Ions are 50% more energy dense.  So a 1.5 hr flight would be reduced to a 1 hr flight.
    • The build.  There are several posts on the building method.
    • Payload impacts on flight time.  Hughes - You always ask the tough questions.  On a flight this long, take the added payload / 10ish to get the minutes reduction.  So if you added a 70 gram Go-Pro, the flight time would decrease about 7 minutes.  Add a 200 gram gimbal, reduce another 20 minutes.  You can see how critical weight is.  This only goes to a point, of course.  Add too much weight and you need to rescale the motors, or increase to an octa and thus increase the number of parallel cells, or use higher C LiPo (an immediate 1/3rd reduction in flight time).  So some engineering is involved in moving up to a 1kg payload.  This ship as it is configured, couldn't carry that much and fly for an hour.  My first attempt would be the octa with maybe 32 to 40 batteries to keep the C low enough and really work on a light weight frame.
    • Level - Bond the ship in stages for a perfectly level platform.  This is discussed in a recent post.  But basically, bond the masts first using shims to keep the masts in plane during the cure.  Then add the motor mounts (taped to the full-scale drawing) on a perfectly flat surface and lay the frame onto the mounts during cure.  Even doing this, one might slip.  Either heat up the mount and remove/rebond or add shims between the motor and mount to get it perfectly level.  I had to do the later on one motor mount.
    • Definitely a family effort.
      • Jim (brother #1) is a retired NW Airlines pilot with an Electrical Engineering degree.  He is constantly trying to push my weak piloting skills (loaning me expensive copters to up my flying time), teaching me efficient flying methods, teaching me how to handle and make electrical parts, and design/build test electronics for identifying the most efficient motors and props.
      • Marty (brother #4) is a maniac flyer doing flips and death rolls.  He will put a copter into a cement wall at 60 mph and expect it to survive.  Most of our build methods come from trying to keep him supplied in ships that can survive that type of abuse.  We are finally there.  He now has a ship that is designed like a car where the passengers can walk away from a 40 mph crash.
      • Dr. Carie, my oldest daughter and astro-geo-microbiologist, came down to co-pilot the event, ensuring that settings and procedures were closely followed for a safe and successful flight.
    • No props at full throttle?  Not only is that an interesting question, I actually don't know why you are asking it.  That might mean that you know something I don't about efficiency for durability.  Care to share your thoughts behind the question before I answer it?
    • Greg - Insightful response that gets at the point of the demonstration.  Once multi-copters are commonly flying for 1 hour or more, the commercial applications will skyrocket.  Builders will migrate to efficient flight electronics, motors, props, and ESCs where weight is minimized and performance maximized.  Light structures will become the norm and off-the-shelf.  Software/hardware developers will be incentivised to build payloads for a slew of useful applications.
  • Great construction! Congratulation guys, and thanks for sharing the details, it will improve new copters :) Was there any damage on the batteries?What would be a safe time of flight not to damage batteries??

  • Congratulations to the new world champions............... guess from the names it was a family effort ;)

  • MR60

    Hi Forrest,

    Very nice write up. For a useful paylod of about 1kg, what flight time would you measure on your setup?

    What glue/bond do you use to glue motors on carbon masts and how do you ensure they are perfectly horizontal, in the same plane?

  • Wow, what a great achievement ? Hats off to you brother ! Pls share your parameters file and some additional info which you feel is required for others to build similar.

  • Nice job to beat microdrones with such DIY project.

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