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what's the diff. between wing and teardrop mast? #157498
10/17/08 05:52 PM
10/17/08 05:52 PM
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erice Offline OP
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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


eric e
1982 nacra 5.2 - 2158
2009 weta tri - 294
-- Have You Seen This? --
Re: what's the diff. between wing and teardrop mast? [Re: erice] #157500
10/17/08 06:11 PM
10/17/08 06:11 PM
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West coast of Norway
Rolf_Nilsen Offline
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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.

Re: what's the diff. between wing and teardrop mast? [Re: Rolf_Nilsen] #157524
10/18/08 08:16 AM
10/18/08 08:16 AM
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Atlanta
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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.

Re: what's the diff. between wing and teardrop mast? [Re: Rolf_Nilsen] #157525
10/18/08 08:25 AM
10/18/08 08:25 AM

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Originally Posted by Rolf_Nilsen
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.


But can you sail upside down with a wing mast?

Re: what's the diff. between wing and teardrop mast? [Re: ] #157541
10/18/08 02:06 PM
10/18/08 02:06 PM
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Eastern NC, USA
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Originally Posted by andrewscott
But can you sail upside down with a wing mast?


I've tried it, it isn't fast.... blush


Tom
Re: what's the diff. between wing and teardrop mast? [Re: tshan] #157559
10/18/08 08:53 PM
10/18/08 08:53 PM

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lol


Re: what's the diff. between wing and teardrop mast? [Re: bvining] #157560
10/18/08 08:55 PM
10/18/08 08:55 PM
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erice Offline OP
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Originally Posted by bvining
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.


a pic would be great!


eric e
1982 nacra 5.2 - 2158
2009 weta tri - 294
Re: what's the diff. between wing and teardrop mast? [Re: erice] #157596
10/19/08 02:40 PM
10/19/08 02:40 PM
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Eastern NC, USA
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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...


Tom
Re: what's the diff. between wing and teardrop mast? [Re: tshan] #157633
10/20/08 03:29 AM
10/20/08 03:29 AM
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North-West Europe
Wouter Offline
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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 Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
Re: what's the diff. between wing and teardrop mast? [Re: Wouter] #157635
10/20/08 03:54 AM
10/20/08 03:54 AM
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Originally Posted by Wouter

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.

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.

Re: what's the diff. between wing and teardrop mast? [Re: erice] #157637
10/20/08 05:13 AM
10/20/08 05:13 AM
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Kingston SE South Australia
JeffS Offline
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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


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: what's the diff. between wing and teardrop mast? [Re: Wouter] #157640
10/20/08 05:56 AM
10/20/08 05:56 AM
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Originally Posted by Wouter
. . .
Wingmast seem to talk more to you and it is easier to find the optimal setting. . . Wouter


I have a terrible time.

Re: what's the diff. between wing and teardrop mast? [Re: fin.] #157647
10/20/08 08:02 AM
10/20/08 08:02 AM
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Posts: 757
japan
erice Offline OP
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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.


eric e
1982 nacra 5.2 - 2158
2009 weta tri - 294
Re: what's the diff. between wing and teardrop mast? [Re: erice] #157648
10/20/08 08:05 AM
10/20/08 08:05 AM
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erice Offline OP
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what no independent pics after the upgrade???


eric e
1982 nacra 5.2 - 2158
2009 weta tri - 294
Re: what's the diff. between wing and teardrop mast? [Re: erice] #157744
10/20/08 04:52 PM
10/20/08 04:52 PM
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japan
erice Offline OP
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erice  Offline OP
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thanks Rick

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eric e
1982 nacra 5.2 - 2158
2009 weta tri - 294

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