3D Robotics

T3 Contest, Round 3

First, congratualulations to Brian Wolfe, the winner of the second round of the T3 Contest. Now it's time for Round 3. This round's objective is to break the Stanford team's UAV altitude record of 7,142 feet by doing at least 24 circles with a 300ft climb and descent in each, as shown above. (This won't really beat his official record, because there won't be an official judge there. But you'll get bragging rights, at least). The winner will have the highest cumulative altitude, but anyone who exceeds 7,142 feet will win a prize. As usual, you must submit a KML track and video in the comments below. Evidence that fun was had is welcome (and may influence Gary's point assignment blackmagic equation), but is not required. Deadline is Midnight PST on November 29th.
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  • T3
    Yes, of course performace will change with altitude.

    Secondly, I observed that there was little conversion of potential energy to kinetic energy due to drag. I didn't have an airspeed sensor installed (I was trying to keep it light and minimise battery consumption) but will post a plot of ground velocity versus altitude. I think that I was able to "toast" everyone by optimising the propellor/motor to the airframe, keeping it a lightweight as possible, optimising climb rate, descending without motor running, putting the servos in the tail, respecting centre of gravity, minimising electronics, keeping the flight smooth, optimising the flight plan, keeping the battery warm, etc.

    This competition was just a kind of simulation and it certainly would not be expected to achieve the same results without the 400ft ceiling.
  • Christophe,
    I am not sure if I will agree with you on the first point - because I canno't see why decreased density of air should decrease performance. Propeller can be selected to be efficient also in thinner air, and drag would be redused. (After all, commercial airplanes fly high in order to save fuel).

    In theory I can agree with you on the second aspect. Potential energy when plane is in the highest position could be exchanged into kinetic energy/increased speed until plane is is lowest pos., then again excanged into height/potential energy. If there was no drag - the plane would theoretically go all the way up to the highest pos. The idea is interesting. However, in practice with those light airframes used (and control loops), I don't think (m)any of the participants did benefit much from this effect. But I will post a speed plot from my entry later, then we can see what really happened. Maybe this effect could explain why Mark Griffin litterally toasted the rest of us in this round? Would be interesting to see his speed plot as well.
  • Congratulations on this very nice flight.

    Please allow me express a few thoughts when one asks himself which altitude could be obtained if climbing for real.

    -First (as you certainly considered) the decreasing density decreases the performance with altitude. Some computations could probably estimate the altitude you would have achieved if climbing for real.

    -But a second aspect is more difficult to estimate as it depends on the implemented control strategy and loops. I would be interested to see some airspeed plots of the latter flights, as when you constantly descend again, it is very likely that there is some kinetic/potential energy exchange that helps to climb the first meters "for free" (especially with a higher aspect ratio aircraft).
  • Moderator
    I think this is how it stands for overall all three rounds combined

    Vassilis 24
    Mark Griffin 16
    Brian Wolfe 13
    Krzysztof Bosak 13
    Brakar 13
    Andrus Kangro 12
    Jesse Jared 8
    MarcS 6
    Bill Premerlani 6
    IOS 6
    Sami Finnila 5
    Chris Anderson 3
    Icebear 1
  • Moderator

    That should be better ;-)
  • Thank you for the clarification about the time-log Krzysztof. As you know I had hard time to belive the log, but chouse to beleive that before my own sence of time. Also thank you for the artistic image which clearly shows what actually was my strategy for this race. Based on experience, I had found that average climbrate with my configuration was something near 20%, and average decline rate about 10-15%. Based on this I made the track consisting of two circles (8 waypoints each) and used the first 6 waypoints for climb and the remaining 10 waypoins for decline. Total length of the track was set to allow for 100m climb and declination.

    It should also be noted that the flight-location is in a quite hilly landscape and that the flight probably was affected by wind/turbulence.

    BTW Gary, it looks like my altitude is the only one given in metres. (I know I have told you before the UK switched to metric units decades ago. However, it's ok with me that you keep pints. In my mind the UK wouldn't be the same without them).
  • Gary,
    I didn't mean my post as a submission. I don't think it would be fair anyway since that flight was back from September before the T3-3

    Since the inspiration behind the competition was to compare to the Stanford record, my goal was to clarify that the official record attempts had used less than half of the batteries' capacity due to winds blowing us off of the allowed airspace. So I was just trying to give the people competing in the T3-round3 a more realistic number to compare to.

    As far as I am concerned, getting to 3000m is a feat (that's what all the teams in the class had done on a 2100mAh battery), and Chris and MarcS surpassed that. A little bit over 4000m was the best we had done with a 2600mAh battery, and Mark definitely broke that. But I find it interesting that although we had different airframes and completely different size of batteries, we achieved similar efficiencies.

    Either ways, it was cool to keep track of the competition! Curious to see what the next one is going to be :)

  • T3
    Hey Gary,
    I'm running a PicPilot (I've also called it a Pic32 Pilot), my own home brew AP - not the commercial Pico Pilot. Minor thing. Thanks,
  • Moderator
    Zouhair, perhaps you could furnish a little more information, I see that your climb topped out at 200m but that must be because you have 60m tall obstructions around you. Do you have a KML and numbers for the total climb?? Maybe I missed it but I can't see either, I have to put the rubbish out for the bin men that might take me maybe 24 hours before I get round to posting the results but Mark chickening out just below 20k seems to have it ;-)
  • Moderator
    Joe, Im very sorry but I can't allow the entry from you guys, it broke the not above 400' rule, but I say that with my tail between my legs as I have followed Dans work for a couple of years and I often quote it as the way forward and containing mucho coolness. Those members here that have not looked at the links here should. We are truly honoured to have such a team join our little bun fight.
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