pinched this line from the N20 thread
And if we're to switch masts (from carbon to aluminum), why not consider a wing-shape rather than teardrop? Might as well upgrade if major changes are going to happen anyway...
someone help me out here, i can't make sense of it
teardrop section is pretty easy to understand
but wing-shape section seems impossible to me as 99% of wings don't have a symmetrical chord section as they only need lift in 1 direction
a mast needs lift in both directions, so it has a symmetrical chord section, so it's basically a teardrop!
OR, does wing section just mean it's longer in the major axis?
if so is there any accepted definition of when a teardrop mast becomes a wing mast?
there is graph on the web somewhere showing wing mast efficiencies compared to major axis length as a percentage of sail foot length
it starts with masts where the major axis makes up 5% of the sail foot and moves up to around 20%?
this would imply that any teardrop section mast that was at least 5% of the sail could be called a wing mast. but that would mean my 26 year old nacra has a wing mast and the general feeling in cat world is that that is not true
so when is a wingmast a wing mast, 10% and up?
or it it something completely different from a teardrop mast
You can have a symmetrical wing. It is not as efficient as a regular wing on an airplane, but it would work. It just depends on the angle of attack of the airstream/wing. That is how planes can fly upside down, greater angle of attack.
You probably refer to Tom Speers work on wingmasts on http://tspeer.com
A wingmast gives more lift for less drag compared to a pear shape. But you have to tune the wingmast right, otherwise it is worse than the pear shape (probably so at least). I would say the pear shape is more forgiving.
I dont think there is a set definition of when a mast becomes a wing mast.
What they are refering to is the shape of the mast's cross section. The Acat and the HT masts have a wing mast shape. The i20 and aluminum Tornado masts were teardrop.
I can post a picture if you need one of both mast styles in cross section.
But can you sail upside down with a wing mast?
I've tried it, it isn't fast.... <img src="<>/blush.gif" alt="blush" title="blush" height="15" width="15" />
lol
I can post a picture if you need one of both mast styles in cross section.
a pic would be great!
I am not an expert, but here goes.... the wingmast is not as
fat
(from beam to beam when mast rotation is 0), allowing for a smoother transition to soft sail. To make up for the lack of
fatness
, the shape is
deeper
(from bow to stern when mast rotation is at 0).
I assume the smoother transition to sail allows for better wind flow and better use of a higher percentage of the sail area (i.e. the frst few inches of sail from the mast). The wing mast also seem to be more
bendier
in the important axis that allows sail shape to be more controllable.....
I have a photo that shows the depth of the Blade wingmast versus a H16 and stock Nacra 18 Square. It is also a good comparison of old sail cut versus new sail cut.... however; I am an idiot and cannot figure out how to attach a picture that is not already on a web site....
Your N5.2 has a tear drop mast, so picture a mast skinnier, but deeper. More bendy from side to side, less bendy front to back. Maybe?
Experts: please correct...
In my opinion the most important feature seperating the teardrop masts from the wing mast is the curvature on the leading edge. With the first it is basically halve a cylinder, with the latter it is an cut-off ellips (the sharp end). The elliptical leading edge has better aerodynamic properties relating to slow seperation and reattachment of the flow further along the sail.
The other aspect is the bending characteristics. Wingmast seem to talk more to you and it is easier to find the optimal setting. Of course the drawback is that you loose the optimal setting more quickly as well.
Nothing is 100% free ride !
Wouter
Wouter
Yeah mine won't shut up! Just rubbishes on about all sorts of stuff, so gets a bit distracting and need to re-focus and tell it to be quiet.
My 5.8 is a teardrop shape and my A is an old ali wingmast, not as stiff as the new carbon ones. Its a trade off with mast rotation as there are times you want rotation but a tight leech. The more rotation the more the main blocks bend the wingmast over loosing power so I have to compromise on the rotation.
regards
Wingmast seem to talk more to you and it is easier to find the optimal setting. . . Wouter
I have a terrible time.
ok, i thinks i've got it now
while searching for pics with google the best 1 came from this site! but i couldn't find the actual thread it was from
anyway, i've pinched the diagram, added some text and attached it to this post
correct me if i'm wrong
when looking at a section of a teardrop mast a circle drawn to touch both sides at it's widest will also touch the leading edge. the trailing edge will generally be an extra 1-3 circle radius out from the circle
when looking at a section of a wing mast a circle drawn to touch both sides at the widest will not touch the leading edge, which generally will be further forward of the circle by about a radius. the trailing edge will be at least 2 or 3 circle radii further out
as the leading edge of a wingmast is
sharper
it's working range of angles to apparent wind is quite narrow, but it works very well within that range so mast rotation adjustment is very important
the blunter teardrop mast isn't as aerodynamically efficient as the wingmast but has a greater working range of angles to the apparent wind, making perfect mast rotation less important.
what no independent pics after the upgrade???
thanks Rick