Sails, Wings, and Winglets

Who hasnt noticed that most new airplanes out there today have 'winglets' attaced to the end of the wings? Some older planes are even being equipped with blended winglet technology. The result is less drag, more effiecient airflow,= less fuel burn.

If we subcribe that a sail is a wing, why not put winglets on top of the mast (some winglets extend both directions, up and down such as the A330). Would you not get the same result? Less Drag, more streamlined airflow?

Has this been tried, attempted, or is it nonsence?

Michael

At the speeds sailboats are operating, I think the drag of the winglet would be far larger then the pressure leak it eventually might stop. The added weight that far up would not do much good for pitching and sideways stability either.

Also, sails and wings are not directly comparable. AoA for a sail is at best 25-30degrees whereas a wing has an Aoa of about 1 degree. The aspect ratio is also way off. All due to the constraints of the different environments the two crafts operate in.


Just my opinion..

Michael,

If memory serves me correctly, Dennis Connor's Americas Cup catamaran "Stars and Stripes" (1988 challenge) had a hard wing sail with winglet "tips" at the top of the mastwing. The mastwing was built and tested by Burt Rutan's company, Scaled Composites in Mojave, CA. The mast tips were added to reduce vortex drag after wind tunnel testing.

I'm not sure if the savings in drag from the winglets will be all that advantageous when considering all of the other things on the boat that cause drag. You have all of the standing rigging, the trap wires, some of the running rigging, spin poles and socks (on some boats), the crew, and harware placed on the mast that will interrupt the airfoil shape... Basically and non-streamlined object on the boat.

Unless the "mastlets" give you a substantial increase in lift they really are not worth the expense. I believe the winglets on the airlines do not increase lift, but just reduce drag (and save about 10% in fuel consumption each flight) by reducing the draga for vortex generation as mentioned earlier.

I may be wrong, but I also don't remember seeing winglets on non-swept wing aircraft. This could be due to the fact that most swept wing aircraft are high speed, heavy aircraft who would benefit from the drag reduction.

what about a bouyant winglet- for a masthead bob- and accomplish 2 things at once

John R.

Michael,

Do a search on Winglets here. We talked about this a while back. Someone mentioned that it had been tried, not sure of the results. I believe the discussion was mostly about mast floats.

How winglets work.

http://www.airandspacemagazine.com/ASM/Mag/Index/2001/AS/htww.html

"Winglets" were tried years ago on A class cats. The principle is sound and the reduction in drag due to the reduction in "tip vortex" is very measurable, the problem with a rotating mast is that to have the winglet as part of the mast, when it is rotated in relation to the sail the "plate" that forms the winglet has to be very large to still offer its effects to the sail on both tacks, the head of the sail has to be "squared" off and attached to the winglet plate by something similar to a "radial traveller" so that sail and the winglet form as near as possible a "one piece" tip. An offshoot of this unsuccessful "experiment" with winglets on masts that is being adopted more and more today was the early application of the square head sail. The same problems are not an issue on aircraft wings as both components are a “fixed” one part. The "Americas Cup" "J" class boats used the same principle at the bottom of the sail when they reduced (to advantage) the "vortex" or "equalisation of pressure" around the foot of their mainsail by using the "Park avenue" boom.

Tigerboy,

Here is a Pic of the winged beast with the vortex reducing tips.

So back to another thread dealing with mast floats that improve performance.....perhaps there is a way to add a similar tip to our boats. Seem more practical than a horizontal winglet type.

And what a magnificent beast it truely was.
Where is it kept now?:

Shame it was not the same shape or even anything like the boat that was challenged in.

It did turn the AC in to what it is now, so I suppose it was progress.

Wasnt that the point? Connor & co did not know anything about the boat the kiwis already had buildt in secret, before they challenged, except the length and width (and boy, was the kiwi boat wide!). The kiwis was obviously thinking "outside the box", and to catch up they needed something really spectacular. There was no requirement for a monohull in the challenge, so they looked at the fastest sailing vessels on the planet, foilers, planing skiffs, trimarans etc., but landed on a C-class on steroids as their best option. They did pretty good under the circumstanses, I would say.


Now, I dont think SS had a proper winglet. I would say they had a tapered top on their wing to reduce tip vortex. I understood winglets to be 90degrees or so to the foil, and their primary function to reduce pressure leakage? Secondary, reduce tip vortices?

There were two of them - The first (a soft sailed version) was once owned by Steve Fossett and I believe is still active in the Great Lakes region in the US (Chicago, IL I believe). I think it was up for sale recently. The second went to a rich guy in Mexico who ran into some financial or legal trouble. The boat sat moored in the water for years (with the solid wing rigged). I saw a picture of it about a year ago where several of the wing panels were missing and boat was very neglected and a terrible state of disrepair. Apparently it came up for sale but I don't think anyone took it home.

I am told the soft-sail Stars & Stripes is in Florida, currently owned by somebody in the Tampa/St. Pete area. I have notes about this and the name of the owner in one of my notebooks, but can't find it right now.

There was a video posted somewhere of the soft sail SS blasting trough a fleet of monohulls. It was made by the new crew/owner, so it's definately sailing. I see that there is a copy on thebeachcats.com..
http://www.thebeachcats.com/modules...&file=index&req=getit&lid=49

Linky no worky

The link worked for me...and it was fun to watch! It took some time to download, however.

That rocks! The look on the guys face on the first monohull (28 or 30 footer) was priceless as she rolled through his lee doing probably three times his speed.

So as not to hijack this thread, I posted my remark about winglet shaped mast head floats here.

GARY

Here is a good winglet
GARY

Gary, could you please post the link in the tinyurl link? For whatever reason, I can't get tinyurls.

I was in Auckland just after Conner lost the Cup to the Kiwis. I was walking around the port area and saw both Black Magic and the humungous challenger on the hard. The failed challenge boat made Black Magic look like a Sabot.

They were both close to the YC where the Cup was kept. I looked in the front door and it was sitting in a case just inside. That didn't last long because some nutter took a hammer to it.

When I was looking for the pic I read something about it being in Key West availible for charter. I didn't pay attention to date so that may have been a while ago. That would be the soft sail version.

other forum thread about mast head floats

Shame it was not the same shape or even anything like the boat that was challenged in.

It did turn the AC in to what it is now, so I suppose it was progress. [/quote]

Fay (I think that was his name) got what he deserved.

1. Perhaps a mast-top winglet system would actually work in wave-piercing cats like A-class cats: Since pitching is not helpful to this concept, the wave-piercers seem to do it less.
2. Has anyone actually tried measuring pitching in wave piercers vs lets say- Marstrom conventional hull shapes?
This could be done from a digital video tape or a CD: at 1 second intervals, measure angle of mast rake for each boat. They should be sailing parallel to another to weather in appreciable waves for several minutes.
Put data on Excel sheet, (or by some magic maths which I do not possess)---determine which pitches less, and how much less!

SS soft sail and wing together

SnS soft sail

SnS wing sail as it sits today...... I downloaded these pics from an advertisement advertising it for sail..... Cannot remeber the site now.

Boat was used for chartered crusies and the boat is very run down..... The wing is riddled with spiders on the inside.

2nd

3rd

can't imagine that its too good for the boat to sit there with the hard wing up.

Imagine if a squall came down through there from the wrong direction... ouch!

Winglets are vertical extensions of wingtips that improve an aircraft's fuel efficiency and cruising range. Designed as small airfoils, winglets reduce the aerodynamic drag associated with vortices that develop at the wingtips as the airplane moves through the air. By reducing wingtip drag, fuel consumption goes down and range is extended.

Aircraft of all types and sizes are flying with winglets -- from single-seat hang gliders and ultralights to global jumbo jets. Some aircraft are designed and manufactured with sleek upturned winglets that blend smoothly into the outer wing sections. Add-on winglets are also custom made for many types of aircraft.

Since the 1970s, when the price of aviation fuel began spiraling upward, airlines and aircraft manufacturers have looked at many ways to improve the operating efficiency of their aircraft. Winglets have become one of the industry's most visible fuel-saving technologies and their use continues to expand.
Winglets increase an aircraft's operating efficiency by reducing what is called induced drag at the tips of the wings. An aircraft's wing is shaped to generate negative pressure on the upper surface and positive pressure on the lower surface as the aircraft moves forward. This unequal pressure creates lift across the upper surface and the aircraft is able to leave the ground and fly.
Unequal pressure, however, also causes air at each wingtip to flow outward along the lower surface, around the tip, and inboard along the upper surface producing a whirlwind of air called a wingtip vortex. The effect of these vortices is increased drag and reduced lift that results in less flight efficiency and higher fuel costs.

Winglets, which are airfoils operating just like a sailboat tacking upwind, produce a forward thrust inside the circulation field of the vortices and reduce their strength. Weaker vortices mean less drag at the wingtips and lift is restored. Improved wing efficiency translates to more payload, reduced fuel consumption, and a longer cruising range that can allow an air carrier to expand routes and destinations.

To produce as much forward thrust as possible, the winglet's airfoil is designed with the same attention as the airfoil of the wings themselves. Performance improvements generated by winglets, however, depend on factors such as the basic design of the aircraft, engine efficiency, and even the weather in which an aircraft is operating.

The shapes and sizes of winglets, and the angles at which they are mounted with respect to the main wings, differ between the many types and sizes of aircraft produced but they all represent improved efficiency. Throughout the aviation industry, winglets are responsible for increased mileage rates of as much as 7%.
Aircraft manufacturers and makers of add-on winglets have also reported improved cruising speeds, time-to-climb rates, and higher operating altitudes.
The use of winglets throughout the aviation industry in the U.S. and overseas is constantly growing. Winglets now appear on powerless hang gliders soaring above mountain ridges and from seaside cliffs. Sailplane builders around the world have included blended winglets to their designs and the sleek, graceful gliders are silently soaring farther than ever Corporate-size Learjet's were the first commercial aircraft to use winglets. Now, several decades later, winglets are incorporated into the designs of many other business jets such as Gulfstreams and the Global Express: a new aircraft built by Lear's parent company, Bombardier.

Retrofitting winglets to existing business jets is also a fast-growing market within the aviation industry itself. Many winglet marketing firms report their products help increase aircraft roll rates and lower approach and takeoff speeds.

Winglets are now quite common on large jetliners and many tower as high as six feet. The first big jetliner to carry the innovation into the air was the MD-11, originally designed and built by McDonnell-Douglas and now part of the Boeing aerospace family. Other Boeing aircraft flying with winglets are the 747-400F, the version currently being built, Boeing BBJ business jets which are custom-built 737s, and the C-17 military transport. Boeing is also offering winglet options on new advanced models of the 737 series of passenger jets.

Most prominent foreign carrier of winglets are the many models of the 300 series of jetliners designed and built by Airbus Industries. The future A380 Airbus, a huge intercontinental double-deck jetliner now under development, will also utilize winglet technology.

The first homebuilts with winglets on the general aviation market were the Vari-Eze and Long-Eze models designed by Burt Rutan, a pioneer in aircraft design innovations. Now, the majority of homebuilt aircraft coming out of shops, garages, and hangars around the world display winglets of varying shapes and sizes.

I had an e-mail discussion a while back with Dave Ellis. I had asked him his opinion about the possibility of masthead floats being designed so they actually give lift, and the possibilities of having fixed or articulating masthead winglets (which he refers to as end plates). Here is one of his responses, and I found it very interesting:

Thank you very much for all the info. Great stuff. I like the idea of using something more 'aerodynamic' than the traditional hobie bob 'football' at the masthead.

Michael

Not only for airplanes. Big butt Fans has added wing tip vortex's to the large overhead fans used in industry to cool factories. These fans operate at lower speeds, generate more air flow. Apparently the engineers have tested with software, wind tunnels, and independent testing.

www.BigAssFans.com

I have used endplates on my RC boat they seem to greatly improve the sail's power, even if the head is twisting off a bit. I even made up a big carbon one (650mm) for my taipan but have never got a chance to rig it up yet.

Picture please?

The concept of an automatic inflation chicken float attached to a square top main and shaped as a winglet has been discussed a couple of years ago in this forum.

The idea was to improve safety and the challenge remains the same: how to maintain or improve performance through the winglet shape, given the losses due to more weight in a bad place (high).

If my memory doesn't fail, the chosen inflation system was a paintball gas cartridge and the winglet-float would be attached to the sail instead of the mast to facilitate maintenance.

Luiz

This is why the genoas on racing mono hulls are so annoyingly low. The deck acts like a winglet to separate the pressures until the trailing edge.

Matt

hmmm...never thought of that. I always knew that the deck sweeping jibs and genny's were higher performance but I never really wondered why (besides the additional sail area)...thanks.

It is either that or the fact that alot of monohull class rules and handicap rules are written in a way that only used the area of the triangle between mast, deck and forestay. This same rule resulted also in designs with small mainsails and huge overlapping genua's. These setups were ONLY faster because the area of the overlap was not taken into the handicap rule while the total mainsail area was. If the rules were written to use actual area's then a larger mainsail and smaller jib would have proven to be faster.

Guys, alot of design features are the result of how the class/handicap rules were written not per se because it is aerodynamically better.

Wouter

End plate effect is accepted dogma for deck sweeping jibs.

To take it one step further. Why doesnt cruisers have deck sweeping jibs? Well, some do, but most of them retrofit roller furling, and recessing the furling drum is a major job. Newer cruisers sometimes have the furling drum recessed, but usually only in the higher price range. Another major problem with deck sweeping jibs in cruisers is lack of visibility, and building lasting opaque sails for cruisers is hard/expensive.