What the hell is luff curve? I checked on google and it seems to be something to do with windsurf sails, or boat sails.Pump me up wrote:6: Luff curve
- If you want a flat luff curve, choose an X2 or similar
- If you want a deep luff curve, choose a Rhino2 or similar
- If you want in-between, choose a Slingshot or similar
- Because rams sit further back in the window than equivalent inflatables (due to drag) they "feel" a bit like the R2, but without the other benefits of an inflatable.
Having limited sailboat experience, I was interested in learning more about "luff curve". This what I found on a web search.
Relating to sails, boat and windsurfer, luff curve is the depth or belly of the sail. The sail cloth/material is cut to allow excess to give profile or "depth".
So PMU is saying that the LEI is a fat belly sail anchored with 2 or 4 lines.
I had some of the best times in my life flying my fat belly sail anchored to a control bar with 4 lines.
So the amount of luff curve being one of the mast deformation factors that introduces dept or foil profile into the sail.mast deformations possible : luff curve, rotation, rake and inclination. -
If related to the LEI, then we're talking about a 180 deg luff curve?
The curve is also on a different axis than used in sail design.
Taken out of context from: http://www.lo0.com/fireball/readings/firezone-a10.htmlLuff curve seems specific to sail design. When talking LEI profile shape IMO we're considering geometry in terms of air-foil design.To understand mast tuning one must know a little about how a sail is designed and what gives it its shape. Seam taper and luff curve are the two main components to sailshape and depth. Seam taper (also known as broadseaming) is the depth built into the sail. Seam taper has a percentage depth (percentage of chord length), a maximum draft position source of the shape you see in your main when you are sailing. When you put a positive luff curve on a straight mast the extra cloth (beyond the straight luff) is cloth added to the depth of the main. Most of added shape appears in the luff. How much luff curve is the question most often asked by sailmakers.
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