erdb

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About erdb

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  1. erdb

    Boats and foils comparison

    Here is the distance between INEOS and LR during the last race: The min distance between the two was 19.24 m at the start. The closest they got during that last cross was 30.9 m. Pretty close to what I got from the scaled screenshot. Of course, this is the distance between the GPS antennas or whatever reference point they calculate from that on the boat.
  2. erdb

    Boats and foils comparison

    I've been doing that already using the TWA, speed and VMG data: In a way it's more accurate, because it corrects for wind shifts (as long as the TWA data is accurate). From the GPS tracks, we could get radius of tacks and jibes by each boat and G forces, but it's not that easy. We could also get minimum distances between boats. That'd be relatively simple.
  3. erdb

    INEOS Team GB

    I've posted it in the other thread: LR missed INEOS by about 31.5m or 1.4 sec. I think at this level, that's a pretty safe margin. INEOS didn't risk collision. They risked being penalized. There was no sudden turn, the boats were approaching each other on mostly straight trajectory, and LR would have avoided collision anyway. What the umpires knew from the GPS tracks, probably seconds before the boats met, that the boats were not on collision course, so even if LR continues straight, they would have never touched INEOS' diamond. Therefore, no penalty.
  4. erdb

    Boats and foils comparison

    Ha, you're right! Somehow I've missed that. It's not Lat/Lon, it's converted to meters, but we have positions with 20Hz frequency! I don't really know what to do with it, but it's cool. Let me know if you have any ideas.
  5. erdb

    Boats and foils comparison

    Funny, I was just looking at that. The boat images don't scale accurately on Virtual Eye when you zoom in, but the little circles showing the tracks of the boats seem to be 3 seconds apart. I scaled the image based on the circles and the speeds of the boats at that time and draw the dimensions of the boats on the image (with yellow lines of course). It seems the closest they got was 31.5m, which at those speeds was about 1.4 seconds. That was the true delta in that race. If LR gets there 1 second earlier, they win and we get to watch another race the next day in 20 kts of wind...
  6. erdb

    Boats and foils comparison

    I haven't seen GPS coordinates so far. At least not in the files I'm able to get based on his instructions. There may be a way, because the virtual eye display needs those coordinates, too. Maybe Dorox could figure out how to pull those as well. I was also wondering about what technology the umpires use this time. I remember in SF and Bermuda there was an additional system on top of GPS that allowed getting boat and camera positions with 1-2 inch accuracy both for the umpires and for Stan Honey's graphics. I wonder if there's something like that now. The on-screen graphics did seem a bit jumpier, especially during the ACWS.
  7. erdb

    Boats and foils comparison

    I've done the height analysis as well, but I don't know how accurate these numbers are. I doubt LR sails 70 cm higher than INEOS. Height during tacks:
  8. erdb

    Luna Rossa Challenge. AC 36

    FCS and its software are the same for all teams. How they cant the foils is up to them and it changes depending on conditions and speed. Here is foil cant angle during tacks for INEOS vs LR. The main difference is that LR dips the new foil deeper for a few seconds after tack while accelerating. We've seen all teams do it during the ACWS. However, INEOS seems to have minimized this acceleration / low foil cant period.
  9. erdb

    Boats and foils comparison

    I haven't implemented the height analysis in my code yet. Do we know where they measure it? Bow? What's the theory behind correlating height with vmg? I think the height numbers could depend a lot on pitch and heel angles and the optimal height may be different for each boat.
  10. erdb

    INEOS Team GB

    Just found this. Very interesting analysis. I like the bubble theory. I always thought their issue was related to some last-minute "upgrade" before the ACWS that completely screwed everything up they had before, but they couldn't change it back because they declared the foil for the ACWS already. Among all the upgrades they did after the ACWS, there was probably one that's responsible for 90% of their improvement, which fixed the main issue. The rest is just the usual development all teams had. I also like the discussion on design foil AOA. I thought a lot about this while making the VPP. It changes a lot of things. As you explain take off is one of them, but I couldn't really model that with my simple tools. However, even at top speed, that foil to foil arm angle determines hull pitch and yaw angles, shifting weight distribution, hull aerodynamics and could also affect how well the keel can be sealed to the water. Tried to compare pitch and cant angles from ACWS race 8 and Prada cup race 1. Unfortunately the conditions were a bit different, but these were the two closest races in TWS. This is all straight-line / steady speed data. Positive pitch angle on these graphs is pitch forward. Upwind ACWS race 8, TWS ~12 kts, boat speed ~31 kts: Upwind Prada RR1: TWS 13.5 - 14 kts, boat speed ~33 kts: INEOS's pitch angle is actually lower in the Prada RR than in the ACWS. On the other hand, foil is canted out more, but that could be the result of higher TWS and smaller jib with lower center of effort, which requires higher cant angle. Also notable that both AM and ETNZ sails with much more pitch forward than INEOS. Downwind: ACWS race 8, TWS ~12 kts, boat speed ~37 kts: Downwind, Prada RR1: TWS 13.5 - 14 kts, boat speed ~41 kts: Same trend downwind, pitch angle is lower for INEOS in the Prada RR thank in the ACWS. Foil cant is higher in the Prada, again that could be because of higher TWS, smaller jib. Once again, both AM and ETNZ sail with much more pitch forward than INEOS. Based on this, I don't think they increased the foil arm to foil angle, because that would produce more pitch forward when up to speed. The changes are probably due to different foil profile, flap control or flap size. What's interesting is that I expected more pitch forward downwind, but that's apparently not the case. The 1st gen boats were sailed very differently. They sailed with a lot more pitch and yaw, especially downwind. Probably the newer foils provide much better lift control with the flaps, and the pitch (foil AOA) doesn't have to change that much as speed increases. This lets them keep the keel closer to the water.
  11. erdb

    Prada Cup

    Both upwind and downwind performances were actually very close. Almost identical VMGs. Upwind INEOS was a bit lower and faster: Downwind INEOS was a lot higher and a lot faster (probably due to the cunningham), but still almost the same VMG as LR. However, last weekend they had much better downwind VMG than LR, so without the cunningham issue, they could have won by a much bigger margin I think. Although there may be a bunch of issues with this "favored tack" analysis, but this is my favorite now for showing what made a difference during the race: Once again, INEOS was far superior tactically:
  12. erdb

    Prada Cup

    So no racing tomorrow either according to Ben. I have to say as awesome the boats and racing turned out, the program sucks big time. Starting with no reserve day for the Christmas regatta, too short or too few races, no plan B if a boat gets damaged, and no rules to make boats come out racing. Knowing the generally shifty conditions, they could have come up with a better system to rearrange the course, too. Set up multiple upwind gates and identify the correct one 1 min before the start. You spend 300 million+ on a program for a couple of 20 min races started when everyone gave up watching due to delays. Disappointing.
  13. erdb

    Prada Cup

    What if the race is cancelled? Does INEOS wins the RR by default or the race is then postponed for tomorrow? What if they can't race tomorrow for any reason?
  14. Hi, Is it possible to get Dorox´s AC36 raw data?

    I would really appreciate it. A zip file would be nice.

    Are you going to take also the one from today´s race?

    Many thanks,
    Saverio

    1. Show previous comments  2 more
    2. erdb

      erdb

      Wow I just realized I have no idea how this forum works. What is a Status Update and who am I talking to? :D

      If you're asking me Dorox, I'm fine now, the method above works perfectly for getting the data off the server and I have my python code to go from there. Thanks a lot again.

    3. X35 GER50

      X35 GER50

      HI Erdb, I got the link from Dorox. Unfortunately I am not a Python specialist. Do you have the different raw data sorted out so that I can plot only what I need (height, vmg, etc).

      I can create plot but I need data already organized.

      Thanks for any help,
      Saverio

    4. X35 GER50

      X35 GER50

      Hi Erdb can you share the data of your latest  plots, LR Vs IN?

      what do you mean by your latest plot, time on the right tack?

      many thanks

      saverio

  15. erdb

    Luna Rossa Challenge. AC 36

    That's a profile I was experimenting with once but it's based on NACA64012 http://airfoiltools.com/airfoil/details?airfoil=n64012-il