Wing mast

[Bogan 8]

Hasn;t Stars and Stripes sat on a mooring for 15 years with a wing mast still up?

[Guest]

I have read this thread and thought I might contribute a bit, as the one who developed Omer wing sail.

 

Wings are more efficient than sails in two aspects; a.wings have better lift/drag ratio, and therefore can provide more driving force, b.wings provide lift while having a smaller angle of attack and therefore are better for upwind sailing.

 

The main problem is not the theory. It is the question of how to make an efficient wing, with simple structure, easy to use, reliable, light weight, inexpensive, and good for all sailors in any weather condition.

 

There are two different ways to approach the design of wing sails:

The first approach is the hard (rigid) wing. This type of a wing sail is the closest to aircraft wing. It is very aerodynamically efficient, has a better aspect ratio and, very high performance with relatively small sail area.

The trade offs are: it has to be a complex structure to enable variable geometry of wing's camber (flaps), it is not reefable, it can't be taken down and folded, it does not have enough sail area in running down wind, and, it is very expensive.

Hard wing sails are very good for extreme speed sailing, for racers and professional sailors, and for other exotic uses. Also, small boats like C class and A class catamaran that have relatively small wings, can benefit the advantages of hard wing sails.

 

The second approach is the soft wing sail. This wing sail is made of sail cloth, and if designed properly, it can be hoisted, reefed and folds exactly like a main sail. It is not limited in size, it is easy to handle, simple as any main sail, no complex mechanics, no "tail" rudders, the wing turns and wind vanes spontaneously, simple variable camber (in "Omer" wing sail it is done by changing the angle between the mast and the boom), no hinges, trailing edge twists spontaneously (no need for internal twisting carbon spars), no moving parts, no problems on anchor or in the marina, and, it is relatively inexpensive.

The trade offs: Soft wing sails are less aerodynamically efficient than hard wing sails, therefore, need more sail area (good for down wind), one has to hoist and fold it, and to keep on with handling sails and sail cloth.

Soft wing sails are good for cruisers and cruiser/racers, and are suitable and robust for recreational service.

 

I truly believe that wings (of all kinds) are the next step in the evolution of sails.

 

It is not any more a question of whether wing sails are more efficient than sails. They are!

 

The questions should be now: what is the right wing sail for a specific use, what is the right wing for a specific sailor, is the wing well designed for it's purpose and, which kind of wing sail is the most cost effective.

 

 

 

Ilan Gonen,

 

Omer wing sail.

[BelowPAR 0]

has a better aspect ratio

Cool post. What is a better aspect ratio? Are you talking very high aspect? And thus needing more apparent to get moving? Is this why we have only seen wings on multis, just because the type of sailing is different and they take the apparent much further forward and there is therefore more of it.??

 

My only understanding of the aspect ratio comes from kitesurfing glider design, in which a low aspect kite equals good low end and easy but slowish to fly, while high aspect is a pain to fly but very rewarding if you handle it correctly.

[Atom Ant 0]

This is an interesting thread. It has been clear for a long time that wing sails are more efficient than soft (traditional style) sails. I guess the direct comparison is a wing and because we are talking wings lets consider an almost direct comparison - a hang glider. I flew hang gliders for around 10 years. When I started hang gliding it had lost its reputation for being a sport for the crazy super brave, but was still largely misunderstood and I suspect still is today. For the benefit of this thread I'm not including parapentes in this but rather hang gliders which have a frame and use sail cloth and battens to form their aerofoil shape. Hang gliders come in two basic styles. One is a lower performing but easier to fly "single surface" hang glider. The sail cloth forms the "top surface" of an aerofoil and has semi flexible battens to stiffen the sail cloth. The shape of the wing is largely determined by the cut of the cloth but is "stiffened" by the battens. This lower performing design is not unlike an ordinary sail on a yacht - flexible, and provides lift but not in the most efficient manner. It's used for training purposes because it's more forgiving, and more importantly it has a low stall speed. It also has a lower lift/drag ratio, and a lower top speed. A higher performance hang glider is known as a double surface. It still uses sail cloth, but has a "top surface" and a "bottom surface". The shape of the wing is also determined by the cut of the sail cloth, but the shape is held more rigid by fixed aerofoil shaped battens, on the top surface and more or less straight battens on the bottom surface. The sail shape can be altered somewhat by changing the shape of the battens but of course this is not for the uninitiated. (this can’t be done on the fly but rather is a process that is carried out after a significant amount of research before one goes changing the wing shape and with it its stability characteristics) This wing has a higher lift/drag ratio, a better glide angle at higher speed, a higher top speed and because it's more efficient it will carry a larger load per sq m of surface area. It is also a little heavier than its single surface cousin, and is not as easy to fly. Some designs will have a higher stall speed too.

 

In both versions the wing tips have “washout” built into them. This is where the wing tip is flying at a higher angle of attack than the rest of the wing. On a yacht this is know as “twist”. For hang gliders it provides some longitudinal stability – in other words it is there to stop them nose diving into the ground.

 

A single surface hang glider will have a max l/d (glide angle where you will glide furthest at a specific speed) of around 7:1. A double surface hang glider will have a max l/d of around 15:1. There may be better ones now but this is good enough for the illustration. Compare this to a normal glider (hard surfaces, higher aspect wing, exotic construction etc) can have a max l/d of between 50 – 100:1. It costs a lot more, uses more runway when landing and can’t be self launched (unless it’s a power glider but that’s a whole other story).

 

A hang glider can be folded up and transported on a roof rack, whereas a glider can be broken down a little bit and transported in a long trailer, but it’s still a bigger permanent structure. It’s just a matter of deciding what you want.

 

So there you have it, soft sails, semi soft wing sails, hard sails, you choose what you want. It would seem to me that the Omer sail design could quite easily be far more efficient than a normal sail, provide far more efficiency for a similar amount of setup time and allow us to enter a new dimension of sailing.

[Fogg 427]

Good one AA!

 

Question - did he die in the end?

[Atom Ant 0]

Yeah Nah Yeah! It depends on what you call another dimension I suppose. There were times while flying when I thought I'd died and gone to heaven but alas no, what goes up must come down, and I always landed on the same planet. Having said that after a while you start to view it from another perspective...

[Guest]

has a better aspect ratio

The higher aspect ratio the less induced drag.

[Guest]

Yeah Nah Yeah! It depends on what you call another dimension I suppose. There were times while flying when I thought I'd died and gone to heaven but alas no, what goes up must come down, and I always landed on the same planet. Having said that after a while you start to view it from another perspective...

 

Correct, Gravity is the 3rd most powerful force in the world.

 

2nd being Murphys Law and

1st being a wife in a bad mood.

[Guest]

I have read this thread and thought I might contribute a bit, as the one who developed Omer wing sail.

 

Wings are more efficient than sails in two aspects; a.wings have better lift/drag ratio, and therefore can provide more driving force, b.wings provide lift while having a smaller angle of attack and therefore are better for upwind sailing.

 

The main problem is not the theory. It is the question of how to make an efficient wing, with simple structure, easy to use, reliable, light weight, inexpensive, and good for all sailors in any weather condition.

 

There are two different ways to approach the design of wing sails:

The first approach is the hard (rigid) wing. This type of a wing sail is the closest to aircraft wing. It is very aerodynamically efficient, has a better aspect ratio and, very high performance with relatively small sail area.

The trade offs are: it has to be a complex structure to enable variable geometry of wing's camber (flaps), it is not reefable, it can't be taken down and folded, it does not have enough sail area in running down wind, and, it is very expensive.

Hard wing sails are very good for extreme speed sailing, for racers and professional sailors, and for other exotic uses. Also, small boats like C class and A class catamaran that have relatively small wings, can benefit the advantages of hard wing sails.

 

The second approach is the soft wing sail. This wing sail is made of sail cloth, and if designed properly, it can be hoisted, reefed and folds exactly like a main sail. It is not limited in size, it is easy to handle, simple as any main sail, no complex mechanics, no "tail" rudders, the wing turns and wind vanes spontaneously, simple variable camber (in "Omer" wing sail it is done by changing the angle between the mast and the boom), no hinges, trailing edge twists spontaneously (no need for internal twisting carbon spars), no moving parts, no problems on anchor or in the marina, and, it is relatively inexpensive.

The trade offs: Soft wing sails are less aerodynamically efficient than hard wing sails, therefore, need more sail area (good for down wind), one has to hoist and fold it, and to keep on with handling sails and sail cloth.

Soft wing sails are good for cruisers and cruiser/racers, and are suitable and robust for recreational service.

 

I truly believe that wings (of all kinds) are the next step in the evolution of sails.

 

It is not any more a question of whether wing sails are more efficient than sails. They are!

 

The questions should be now: what is the right wing sail for a specific use, what is the right wing for a specific sailor, is the wing well designed for it's purpose and, which kind of wing sail is the most cost effective.

 

 

 

Ilan Gonen,

 

Omer wing sail.

 

 

so they'd be perfect for a mullet boat

[Guest]

so they'd be perfect for a mullet boat

Now that would make a few people turn in their graves.

[Guest]

there is a compromise that hasn't really been explored to much and that is the use of "cams" like windsurfers use in some types of race and freeride sails.

 

These "cams" create very powerfull sails, and the difference is especially noticable if the breeze is a bit up and down. The Sails of the same size but with cams allways sail through the light spots without even noticing, while the normall RAF type sails tend to die in the light spots.

 

there is no reason why a "cam" like batthen system coudln't be developed for a normall rig. There are some challenges to overcome for sure, but it sure would be interesting to try.

 

would there be performance benefits.....I have no idea.