T3 Back to the Future


Remember back, way back in autopilot years probably about 20. The year 2009 and the first round of our gentlemens (ladies are allowed just none have ever entered) competition the T3 challenge.

Back then just flying way points was hard and all this gear was expensive. Ardupilots were made at Sparkfun in batches that ran out quick.


Lets try it again I suspect this time the challenge would really be flying it faster than somebody FPV racing.

Read about the first time here for hints and tips. 

As tech has moved on all aircraft types welcome lets make it not above 50m and 5 laps. All of course autonomous. Extra marks if that is from take off to landing.I will count the time from take off to landing so screaming dives to the start will not help. KMLs as evidence please!

UPDATE: Rovers (and boats) are also allowed! There will be a special rover/boat class, and you only have to beat other vehicles in that class. The course for such ground/water vehicles is 100m x 100m. 

I will accept FPV times for the sake of science and should they be much much quicker it will give the pure FPV crowd something to brag about.

An Easystar (yes before HK copied it) made one lap in less than a minute in 2009 so 5 in 5 minutes should be more than possible. 

As ever the time frame is flexible but why don't we all meet back here on August the 1st and find out who won!

Please add your entries and adventures below. Points are always awarded for silliness, just as long as its safe!


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  • @TCIII
    I'm only kidding about the extensions. I'll welcome any extra time we can get.

    I was in such a rush to meet the deadline that I was making costly mistakes. This time I'll pace myself and rebuild carefully.

    I just talked to Traxxas support about the always-on esc, they've agreed to replace it as well as the one that I smoked. For a small fee of course, but considering they're a few years old, it's a damn good deal.
    Great customer service.

    Frantically rebuilding,

  • Admin


    Well I and my support crew went to my T3 overflow parking lot course only to find puddles as deep as 3 inches. It had rained last night and it rained this afternoon and it looks like it may rain this evening.

    My Crusher Rover is water resistant, but 3 in deep puddles is pushing it. 

    It takes about two days without rain for the parking lot to dry out.

    Waiting patiently.



  • Another week? Just when I thought the pain was over.
    On Friday I hit a goal post and did more damage. After burning out the esc last week I sloppily put the wires back in with my XT60 under the motor wires rather than on top. The heat from the motor melted the solder in the connection but was contained within the heatshrink, until hitting the pole. Now there's solder everywhere. Steering servo saver post snapped off, and my gps module landed ~10' away. Ouch!
    For some reason, the replacement esc is always on when powered, and is overheating on the bench while plugged in but not moving, and one of my 3s lipos now has a bad cell.
    APM is showing a yaw drift of about 5°/s with the same gps/mag that I used with pixhawk. I'll try erasing eeprom then reloading firmware.
    I was quite upset yesterday about not submitting a decent run, but also satisfied that I did all I could.
    Guess I'll start a full teardown/rebuild tonight.
    I refuse to quit.
    @Gary_ Please no more extensions

  • T3

    Okay, I went out and gave it another try to see if I could get it any faster. Here's the result.

    3702067178?profile=originalI knocked 57 seconds off the time for a total of 316 seconds. Not bad and it was running fairly well. Max speed was around 10.5-11 ms^-1 on the straights. I quickly tried putting intermediate waypoints but it only seemed to slow things down so I went back to my 4 waypoint mission to get this done.

    Here's the KMZ file.

    Faster Submission

    I did find again that if you modify either of the NAVL1 parameters within the Tower app, it will crash.

    Also, I don't know how you do this but I know in MP, when you make a mission, you can tell it to essentially repeat a mission after drawing the four waypoints. When I downloaded the points from the rover onto my phone, it only grabbed the 4 points. There was no way to repeat. It's probably a limitation within the app but it's something I noticed.

    I also found that if I am in the middle of a mission and abort by going to MANUAL, it will stop. When I put it back in AUTO, it will resume the mission. However, if I load a new mission after I go to MANUAL, it seems to want to go to the next waypoint of the original mission before starting the new mission. Am I missing some setting or is there a way to reset it? I have tried pulling the CH7 switch in AUTO to have it RTL and while it comes back, it will then try to continue to the next waypoint before starting a new mission. That was kind of difficult to deal with.

    Anyway, there's my new submission.

    Dropbox - Link not found
    Dropbox is a free service that lets you bring your photos, docs, and videos anywhere and share them easily. Never email yourself a file again!
  • Admin

    Hi Gary,

    Fine by me.


    Tom C AVD

  • Moderator

    If there are no objections from our early entries, I might just let this competition roll on until next Monday then absolutely close it. So the hammer really really really will fall on Monday the 17th of August..... That gives everybody one more week to prepare and weekend to try.

  • Admin


    The rover only slows to make the turns otherwise it moves at the CRUISE_SPEED setting until it comes to a turn.

    At high CRUISE_SPEEDS (12 - 15m/s) I set the SPEED_TURN_DIST to around 30m from the turn and go for a SPEED_TURN_GAIN percentage that gets me around 5m/s for the turns. That way I can run at very high speeds in the straightaways, but slow enough before a turn to minimize any overshoot or roll over.


    Tom C AVD

  • T3
    So the braking parameter doesn't go into effect for those points then? I have my vehicle slow to 35% of cruise throttle at 75% for the turns so I would have thought intuitively that it might slow X meters from each waypoint.
  • Admin


    The additional waypoints in the straightaways do not slow the rover down one bit as far as I can tell.

    They just keep it on a straight and narrow path from the beginning waypoint through each turn and then back to the beginning.

    The surface of the parking lot that I am running on is full of dips and rough patches that can throw the rover off course without the additional intermediate waypoints.

    Once I get a T3 run in early this week with the telemetry working correctly I think that I can show a very straight point to point tlog run. I did not see any weaving on the straightaways during the runs that were done without the telemetry.


    Tom C AVD

  • T3

    Why so many point in your mission? Wouldn't that slow things down?

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