That sounds great Chris.
We'll be taking measurements to put into the JavaScript program at
https://ushawks.org/designer/.
The first thing to note about the actual program is that many of the locations and lengths are relative to other locations and lengths. This is helpful for a program where you want to vary things and have them properly affect other things. But for taking raw measurements, this "everything is relative" approach is somewhat difficult. So I've created a form (below) that makes it easier to capture the raw measurements as absolute values. We can then convert those to the relative measurements that the program expects. With that goal in mind, here's how you should take the measurements to fill out the form (below).
You will probably want to print the form so you can have it with you. If you can't print it, then just write it down on paper so you'll have it in your hands when you do the measuring. You can use any convenient units, but it's best to use the units of your measuring tape to reduce conversion errors. In most cases that will be feet and inches. That way you can just write them down on the form. Also, there may be some things that are hard to measure. Just make your best estimate, and write it down. We can always change it later.
Start with the glider fully set up, and be sure that it is properly tied down and secured. We will need it fully set up to get the locations (x,y,z absolute coordinates) of the wing geometry. It might be convenient to have the keel be as level as possible.
The program assumes that the "y" axis lies along the keel, and that the "z" axis is up. That means that the "x" axis points out toward the right wing (for a right-handed coordinate system). The
origin (where x, y, and z axes meet) can be anywhere along the keel. But for this procedure, we're going to pick the location where a line joining the two wingtips crosses the keel because it simplifies the measuring process. The easiest way to find this
origin is to stretch a string from one wingtip to the other and mark the keel (using tape or marker) where that string crosses the keel. We will call that point the
origin of our model.
Once you have the
origin, you can begin to make the 18 measurements and fill out this form:
| Name | Value | Description |
| Length of Leading Edge | | Length of the leading edge from nose to tip |
| Length of Keel | | Length of the keel |
| Keel Front y | | Distance from the origin to the front tip of the keel |
| Keel Rear y | | Distance from the origin to the rear tip of the keel |
| Wing Tip x | | Distance from the origin to the right wing tip |
| Wing Tip z | | Vertical distance between the origin and right wing tip (this might be hard to measure, so just estimate it) |
| Control Bar Height | | Vertical distance from the base tube to the keel (perpendicular distance from the keel to the base tube) |
| Control Bar Width | | Width of the base tube from corner to corner |
| Control Bar Location | | Distance along the keel from the nose to the apex of the control frame |
| Control Bar Rake | | Horizontal distance along the keel from the apex of the control frame to the base tube (this may be hard to measure, so just estimate it) |
| Cross Bar at Leading Edge | | Distance along the leading edge from nose to cross bar junction where the cross bar meets the leading edge |
| Cross Bar at Keel | | Distance along the keel from the nose to the cross bar where it crosses the keel |
| Cross Bar z from Keel | | Vertical distance between the keel and the cross bar (typically 0 to a few inches) |
| Kingpost at Keel | | Distance along the keel from the nose to the kingpost (you can also measure from the rear of the keel and subtract from the keel length) |
| Kingpost Height | | Vertical distance (perpendicular to keel) from the keel to top of the kingpost |
| Kingpost Rake | | Horizontal distance (parallel to keel) between top and bottom of kingpost |
| Trailing Edge | | Distance along the keel from the nose to the trailing edge of the sail |
| Rear Wire | | Distance along the keel from the nose to the rear wire where it attaches to the keel |
Please call or text if you have any questions.
Have fun!!
Posted: Mon Sep 13, 2021 12:41 pm
