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Measuring junk sailing performance

  • 11 Oct 2019 15:57
    Quote
    Reply # 7928309 on 7926219
    Deleted user
    Anonymous wrote:
    Robert wrote:

    Will need updates to the JRA Tested Boat specs, e.g. is the sail area of the Weaverbird wing the same as the single-ply sail?

    rself



    I can confirm that the sails are of the same area and planform.

    OK David. Thanks. No change with Weaverbird.

    Anyone with knowledge of Amiina specs willing to fill in the spreadsheet?

    1 file
  • 10 Oct 2019 08:16
    Quote
    Reply # 7926219 on 7923053
    Anonymous member
    Robert wrote:

    Will need updates to the JRA Tested Boat specs, e.g. is the sail area of the Weaverbird wing the same as the single-ply sail?

    rself



    I can confirm that the sails are of the same area and planform.
  • 08 Oct 2019 17:13
    Quote
    Reply # 7923053 on 4913961
    Deleted user

    Amiina 2019 polar plots....and Weaverbird single-ply cambered sail polars from 2018 for comparison.

    There is a pocket of anomalous Amiina data (see draw_circle.jpg of boat speed vs true wind speed plot) which pulled the median boat speeds off the curves for 12, 14,and 16 knt wind speed (TWS) polars. The circled anomalous points show Amiina going at less than 1 knt in 15 knts of wind. Not actually sailing? In the polars the anomaly is obvious so I leave it to the viewer to fit-by-eye the single median at 70 deg TWA that's off the curve.

    The Amiina sample size of 10,000 sentences gives a very good look at the boat's performance.

    Best I can tell overall Amiina and Weaverbird (with the single-ply cambered sail) are nearly equal.

    Amiina view and download link:

    https://drive.google.com/drive/folders/1c4c41vK4vYFG7kirp1nBfaE0kYZ8KWBa?usp=sharing

    I'll add Weaverbird with wing sail and Amiina to summary plots similar to those found in Reply # 6936247 on 6922879.

    Will need updates to the JRA Tested Boat specs, e.g. is the sail area of the Weaverbird wing the same as the single-ply sail?

    rself


    19 files
    Last modified: 08 Oct 2019 17:20 | Deleted user
  • 06 Oct 2019 16:47
    Quote
    Reply # 7919979 on 4913961
    Deleted user

    Weaverbird wing sail polar plots.

    Only the 10, 12, 14, and 16 knt wind speed wingJR polars had ample sample sizes for meaningful comparison with stndJR polars from 2018.

    But all the polars can be viewed and downloaded here :

    https://drive.google.com/drive/folders/1qmtQxcRnPYB7VPQIPNTQk14KtHnXrxE7?usp=sharing

    11 files
    Last modified: 06 Oct 2019 16:50 | Deleted user
  • 05 Oct 2019 18:08
    Quote
    Reply # 7919044 on 7918380
    Anonymous member
    Anonymous wrote:

    Are weaverbird close reach boat speeds different between port and starboard tacks due to mast effects?

    rself
    Is it just my browser? or is this font really , really small?
  • 04 Oct 2019 20:46
    Quote
    Reply # 7918380 on 4913961
    Deleted user

    Are weaverbird close reach boat speeds different between port and starboard tacks due to mast effects?

    In 2018 performance data was collected on Weaverbird which had a single-ply, cambered JR. In 2019 Weaverbird was fitted with a wing sail which encloses the mast and data collected again.

    The results for beat and close reach courses (4 plot figure), true wind angle (TWA) between 30 and 60 degrees, show that on average stbd tack speeds are a slightly greater than port tack speeds for BOTH enclosed and exposed mast sails. 

    The 2018 and 2019 wind conditions [TWA (deg)vs TWS (knts)] shown in other two figures.

    Mast effects were put forward in the early days of JR when single-ply flat panels were the norm. Perhaps flat sails and mast effects co-occur?

    If flat sail performance data were collected for Weaverbird comparisons could be made with already in-hand wing and cambered data.

    download link:

    https://drive.google.com/drive/folders/1MxsHDyOtmWSc_vJ62ji69oiiZr2rsM6L?usp=sharing

    rself

    3 files
    Last modified: 05 Oct 2019 14:43 | Deleted user
  • 30 Sep 2019 02:33
    Quote
    Reply # 7908666 on 7908394
    Deleted user
    Anonymous wrote:

    Can these diagrams tell us something about Amiina's performance?
    To me it looks mainly as modern art  -  that is, it looks cool but tells me nothing...

    Arne

    Hi Arne--Not yet. I haven't gotton to the polar plots yet. It takes me time to familiarize myself with my code after a year.

    It should tell you though about the real world of data collection before its boiled down to nice curved lines in polar plots. Very messy with lots of variablity. But the graphs of wind speed vs wind angle compared across amiina vs weaverbird wing vs weaverbird standard will give you an idea of the conditions during each of these data collection periods. See JRA newsletter #79 for Alan's explanation of relevance.

    amiina vs W-wing vs W-stnd scatterplots lnk: plots are gridded...easier to compare.

    https://drive.google.com/drive/folders/1MpvHNonVcskcP8pcqrq9IpaqmeZKwrGF?usp=sharing

    Last modified: 30 Sep 2019 02:46 | Deleted user
  • 29 Sep 2019 23:00
    Quote
    Reply # 7908394 on 4913961
    Anonymous member (Administrator)

    Can these diagrams tell us something about Amiina's performance?
    To me it looks mainly as modern art  -  that is, it looks cool but tells me nothing...

    Arne
  • 29 Sep 2019 15:10
    Quote
    Reply # 7907803 on 4913961
    Deleted user

    Amiina 2019 boat speed, wind angle and wind speed plots. Port tack vs stbd tack overlay to see if there is any difference.

    Alan et. al. also collected reefed sail vs full sail msmts which I've plotted up as an overlay. One of the histogram plots is included comparing the "reefed" wind speeds aganist the "full" wind speeds to see if the file designations made sense. They do. "reefed" -> greater than 10-12 knts wind and "full" -> less than 10-12 knts.

    Amiina view and download link:

    https://drive.google.com/drive/folders/1c4c41vK4vYFG7kirp1nBfaE0kYZ8KWBa?usp=sharing

    amiina vs W-wing vs W-stnd scatterplots lnk: plots are gridded...easier to compare.

    https://drive.google.com/drive/folders/1MpvHNonVcskcP8pcqrq9IpaqmeZKwrGF?usp=sharing

    rself

    7 files
    Last modified: 29 Sep 2019 17:27 | Deleted user
  • 28 Sep 2019 18:53
    Quote
    Reply # 7907088 on 4913961
    Deleted user

    Weaverbird 2019 wing sail plots and comparison with 2018 W-standard rig.

    These are the port-stbd-tack comparison plots which more-or-less overlap so (like the 2018 data) I won't be separating them. 

    weaverbird view and download link

    https://drive.google.com/drive/folders/1qmtQxcRnPYB7VPQIPNTQk14KtHnXrxE7?usp=sharing

    It occurred to me that there is an opportunity to do a mast effect comparison. Weaverbird current wing sail encloses the mast. 2018 standard junkrig exposed the mast. Closest to "everything-else-being-equal" as possible. I believe current consensus is the mast effect on upwind courses is small, if existent at all.

    So the expected result is equal overlap of boat speed frequency distribution(s) between wing and standard for upwind courses (30-60 deg?).

    rself


    6 files
    Last modified: 29 Sep 2019 15:14 | Deleted user
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