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distance front wing from mast?

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windmlv
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distance front wing from mast?

Postby windmlv » Mon Oct 12, 2015 6:18 pm

Looking at different foils it appears some front wings are very close to the mast and others further away.
So what difference does that make in performance/stability etc.?
Or does it even matter?
Just curious and I know that we have a lot of foil theory forum users on here.

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Re: distance front wing from mast?

Postby Denisesewa » Mon Oct 12, 2015 11:57 pm

closer to the mast is stronger with less stress on the fuselage, trim and mounting position of the mast on the board take care of any other differences, no perceivable performance advantage to the different designs, just strength IMO.

windmlv
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Re: distance front wing from mast?

Postby windmlv » Tue Oct 13, 2015 2:11 pm

Thanks, I can understand the "less stress" on the fuselage.
It appears most foil designers are opting to go closer to the mast.
Still wondering if there are other advantages or disadvantages that I don't know of.
I don't see any with the front wing directly under the mast which in theory would be the strongest but may upset the stability.

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Re: distance front wing from mast?

Postby Stefan » Tue Oct 13, 2015 4:56 pm

windmlv wrote:Thanks, I can understand the "less stress" on the fuselage.
It appears most foil designers are opting to go closer to the mast.
Still wondering if there are other advantages or disadvantages that I don't know of.
I don't see any with the front wing directly under the mast which in theory would be the strongest but may upset the stability.
Strength is the main advantage, but it changes the balance point so having an adjustable track (4 bolt) is a good idea if you're not use the same manufacturers board.

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Re: distance front wing from mast?

Postby Maic » Mon Oct 19, 2015 7:57 am

Hi, we built and we actually ride this:

Image

http://www.bladefoil.com for more pictures

The simple concept behind it was to make a stiffer and simpler to assemble foil,
and we are very proud to say that all works as we aspected.

You can change a wing or the entire fuselage in a very few minutes.
with this design we basically put the base for a foil platform that can evoluted for a good numbers of years just making research and development on the wings and the fuselage.

As you can see from this image if you ride a spotz foil you must not change nothing on your board.

Image

the "axial mast" feel very very strong and stiff as costruction.
so it works...!!!!

we are based in central Tuscany, Italy.
Maicol

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Re: distance front wing from mast?

Postby revhed » Mon Oct 19, 2015 8:39 am

Strange that when we test flew this design idea MANY years ago it would not turn well and just felt wrong.
This design idea seems to makes sense in that having the STRUT mounted directly over, or very close to the F wings lift takes most of the stress away from the fuse,
and makes the STRUT to board mount postition, or close to, equal distance beteen your feet, like Spotz.
This also reduces the lever force on the board as compaired to the conventional design.
So not really that hard to come up with this design from a structurally efficient point of view, thats why it was tried.
I question how well your "new" design idea turns and feels?
It sure looks like there is very little surface area between the bottom of the STRUT and the F wing
I wonder how stiff and durable this connection is?
R H

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Re: distance front wing from mast?

Postby windmlv » Mon Oct 19, 2015 2:30 pm

Interesting concept from "Bladefoil". Photos/video of it in use?
I just realized that I used the term "mast" as a heading for this thread.
Okay, the vertical "thingy".

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Re: distance front wing from mast?

Postby Peter_Frank » Mon Oct 19, 2015 2:48 pm

If the mast is positioned further forward (or has a hugely swept shape) or rearward, the turning dynamics and directional stability will change by a huge factor IMO.

I dont know if for better or worse and how much, but it will definitely change a lot.

For example - if it does not track as good if mast forward, you have to put a bigger rudder/stab/swept rear wing instead, which means more drag and it might turn at a larger radius (less lively).

Mayby not the case I dont know, just an example of what one could think might happen :naughty:

It is all about the turning dynamics, as you have a huge surface on the mast as a pivot point, and mast will act as a stabilizer to some extent if aft of the wing COE

They will all work of course, but differently :D

8) PF

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Re: distance front wing from mast?

Postby Bille » Mon Oct 19, 2015 4:40 pm

Peter_Frank wrote:If the mast is positioned further forward (or has a hugely swept shape) or rearward, the
turning dynamics and directional stability will change by a huge factor IMO.

I dont know if for better or worse and how much, but it will definitely change a lot.
...

8) PF
Same thing happens, when Ya change the sweep angle of the rudder, on a
catamaran ; the Helm will react , WAY different !!

Bille

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Re: distance front wing from mast?

Postby abel » Mon Oct 19, 2015 6:01 pm

Denisesewa wrote:closer to the mast is stronger with less stress on the fuselage,
trim and mounting position of the mast on the board take care of any other differences, no perceivable performance advantage to the different designs, just strength IMO.
I have to disagree on the "less stress on the fuselage"
(stress= moment on the fuselage and the mast that want to rotate them towards the board)

The moment forces on the attachment point of the fuselage should be balanced.
i.e. short length for big surface for the front wing; and larger length for smaller surface on the rear wing.
Normally the moments shall ~cancel each other and there will be only an axial force along the mast.
On the other hand, an example of worst case would be nosing up at high speed and having the front wing out of the water.
If the mast is on top of the front wing the max. moment will be relative to the entire length of the fuselage.
If the mast is e.g. 1/3 after the front wing, then the moment on the fuselage will be smaller by ~33%.
The moment on the mast will also be lower (but at lesser degree)


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