I think its time for a new DIY Drones contest which I would like to propose.
The T3 is fun, but it doesn't have any real point other than the winner gets some bragging rights.
At the end of the day, speed is not the goal for most of us so a competition that measuers speed yields no useful information that helps us move forward as a group.

The contest I would like to proprose is an ongoing endurance contest, instead of running over a timeframe, it is continuous and reviewed weekly so that the leaderboard shows who currently has the greatest endurance on each given platform. (Lets stick to commercially available models not custom built ones).

As part of the contest you would submit information such as prop size, battery capacity, cell count, model, weight and payload details etc.
The benefit of this is that we would be able to tabulate the results and publish a document showing the endurance relationship to weight and battery capacity for every type of model that is commonly flown.

That would save us all a LOT of messing around and would be a golden resource for newcomers, even the FPV community could benefit from the data we can extract from an Autopilot.
For each model eg Skywalker, Bixler, Skyfun etc we would be able to publish recommended motors, prop and battery for maximum endurance.

This would also be an excellent resource for people who are trying to choose the right platform.
For example, if you know you need to lift 500 grams of payload then you can find out which model is going to be able to do that with the longest endurance. It would even give you the battery, motor and prop choice in order to achieve your goal.

This information is basic stuff that almost all of us struggle with and can end up costing a lot of money through trial and error trying to figure out. My thinking is that the hardware and software are open source, yet our own individual knowlege is not collated very well, you have to read through thousands of conflicting forum posts to try and put it together yourself. If we all worked together and shared the information we learn daily, then it will make it easier for all of us and we would have some scientific measures behind a lot of the 'opinions' that go into current recommendations. Just as important as the sucessful combinations are the failed ones as these can act as "don't do this" examples for newcomers. These aren't captured anywhere at the moment.

You can also use the data to benchmark changes you make to your own platform, if we have a standardised way of measuring endurance, then instead of just saying "I got 35 minutes" in a post, you can actually measure your real relative performance to other setups, then measure the increase or decrease in performance when a change is made to one of the variables.

The other benefit of this is that it will also push manufacturers to consider efficiency more as they try and get their products into the leaderboard, especially on the airframe front.

I am happy to co-ordinate it and get it off the ground if there is support from the leaders here at DIY Drones.
I can build something to collate and deseminate the data and perhaps later on down the track we could webify it so it is fairly automated.

The key thing where I might need some help is measuring the endurance from a log file in a way that is fair and ideally automated.

I forsee the goal would be something like...

- Launch
- Fly at the slowest speed possible without stalling in Auto mode
- Loiter over a target with 100m radius until your battery cuts out
- Land

Details to be accurately recorded in order to have a valid entry:

 

Model Type: eg Skywalker, Skyfun, Bixler etc
Model Modifications: eg removed landing gear
All Up Weight: preferably metric
Cell Count: 2S, 3S, 2P4S etc
Battery Capacity: in mAh
Battery Manufacturer / Model:
Battery weight:
Motor Brand:
Motor Model:
ESC:
Prop Spec:
Payload Description: GoPro etc
Payload Weight:
Approx average speed during flight:
Attach log file:

For each model we will record the out of box dry weight as a comparison.
There would be no restriction in terms of the numbers of entries per person, the more times you enter, even with poor results, the more valuable the data would become. I would encourage people to enter with every combination of battery they can for their model type.

So what do you all think? 

Views: 1484


3D Robotics
Comment by Chris Anderson on January 5, 2012 at 2:25pm

Toby, cool ideas and in line with what Gary and I have been discussing for future rounds. The next round, however, will be announced tomorrow and is an autotakeoff and landing round. Just a point of clarification: most of the T3 competitions are not based on speed (you can see the full list here), and the winners get actual prizes, not just bragging rights. 

Comment by Toby Mills on January 5, 2012 at 2:35pm

cool, thanks for the clarification chris.

 


100KM
Comment by Hein du Plessis on January 5, 2012 at 2:44pm

Great idea Toby, if well published, the results will be invaluable to newcomers (and me!)

Just a few suggestions:

- I'm not too keen on flying until my batteries cut out :) They (the batteries) are quite expensive not to mention risking my whole rig! Perhaps distance per mAh consumed?

- Maybe loiter is not the best mode to test with since the model will be continuously turning. A straight line would be easier to compare performance.

- Also important to mention re. the battery is the discharge capability, eg 20c / 15c. Higher discharge rates = heavier batteries.

My contrib:

Model Type:     Skywalker V4
Model Modifications:     Minor reinforcements
All Up Weight:     ~2.2kg
Cell Count:     3s
Battery Capacity: 10000 mAh (2 x 5000)
Battery Manufacturer / Model: Zippy
Battery weight: 808g (404g ea)
Motor Brand: Scorpion
Motor Model: Scorpion SII-3014-1040 Brushless Outrunner M
ESC: H-KING 50A Fixed Wing Brushless Speed Contro
Prop Spec: APC style propeller 9x6-E
Payload Description: Nothing Besides Basics
Payload Weight:
Approx average speed during flight: ~35kph
Attach log file:

I don't have a way to measure mAh used at the moment, but I can say I've flown 13.3km and battery voltage went down from 12.6 to 11.9.

Comment by Toby Mills on January 5, 2012 at 2:55pm

The ESC will cut out before the battery gets to an unsafe level of discharge, if you fly your circle 10m above the ground then you can safely land without risking your plane. Alternatively if you know its about to run out, then you can land at that point and end slightly early.

I was thinking it might be best to keep clear of getting people to measure mA per hour themselves because not everyone has a current meter and also it introduces variation (no gaurantee the current meter is calibrated correctly).

My thinking around a circle was that it eliminates wind to a degree. If you go in a straight line then wind hits you constantly in one direction. If you circle, then the wind is behind you and in front of you for the same amount of time, thereby eliminating it (to a degree) as a factor.

A straight line might also not be practicle at the higher end of endurance, my skyfyun can fly for 38 minutes and cover 20+km in that time which would be illegal in most countries to fly out of sight. A circle keeps it a level playing field for everyone and makes it easy to land when you run out.

 

 

Comment by John Culp on January 5, 2012 at 3:12pm

This subject is also drawing interest at the rcgroups grim reaper wing thread.  Here's a report of a 72 min. flight:

http://www.rcgroups.com/forums/showpost.php?p=20312026&postcoun...


100KM
Comment by Hein du Plessis on January 5, 2012 at 3:19pm
The default cut out for my esc (and I guess its pretty standard) is 3.5 volt which can reduce battery life. I'm also not that good a pilot to land without the option to come around again...

Most of my flights involve zigzags with me in the center so the model is always in line of sight.

The tests should be done when there is little or no wind, I think, otherwise the figures can't really be compared. Gliding downwind does not compensate for the struggle upwind.

Just my thoughts..
Comment by microuav on January 5, 2012 at 3:31pm

see @ the imav2011 outdoor rules the endurance element.

http://www.imav2011.org/competitions/explanation-missions


The jury needs to measure the total capacity of the battery used for the
endurance MAV. The team will use an energy logger that is provided by the
organization to charge the empty battery that will be used for the endurance
flight to its full charge. The logged energy is the total energy in the above
equation. This will be done on the practice day prior to the competition day.
Immediately after the team’s competition slot, the same battery will be recharged
by the team to its full charge using the energy logger. The logged energy is the
used energy in the above equation.

Comment by Toby Mills on January 5, 2012 at 3:34pm

@microuav yes this would be great, but a little impractical for a global challenge that is ongoing.

We need a method that is easy for beginners to use and is repeatable globally by anyone without specialist equipment. We are not going to get perfect results but we should see very useful approximations.

It sounds like there would be concerns about running batteries flat. Perhaps we would have to leave it up to peoples discretion on when they stopped. Not everyone has chargers that measure how much energy was put back into a flat battery.

 

Comment by Dez Socks on January 5, 2012 at 3:48pm

Excellent idea.Stops searching through forums looking at other peoples set-up that may or may not work

I'm sure we can find a accurate way of measuring amount of energy consumed even if there is slight variation.We cant count on all factors as weather,wind,quality of battery etc being the same but as a group these variations can be accounted for by taking a lot of averages not just single tests.Maybe a restriction to mods on the outer frame due to aerodynamics affecting flight time eg. camera,exposed antenna,gps etc.


3D Robotics
Comment by Chris Anderson on January 5, 2012 at 4:02pm

BTW, we'd like T3 competitions to be open to both planes and copters from now on. Low battery situations with copters are a lot scarier than with planes, so I think endurance is risky without good telemetry giving battery capacity.

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