The International Hydrofoil Society (IHS) Hydrofoil Correspondance Archives

General: IHS Administration Design of Foils: Foil-Struts-Controls-Performance Design of Vessels: Hull-Machinery-Costs-Performance/Ops History of Hydrofoils: People-Vessels-Operations Hydrofoils: Commercial Hydrofoils: Military
Hydrofoils: Models Hydrofoils: Pleasure Hydrofoils: Sailboats R/D: Student Projects/Thesis etc. Sources, Buy/Sell: Brokers-Builders-Designers-Operators Miscellaneous:Hybrids-Other High Performance Vessels-etc.

Updated last February 27, 2005

Miscelaneous: Hybrids-Other High Performance Vessels-rtc.



Miscellaneous:Hybrids-Other High Performance Vessels-etc.      Scroll To Top Top

    Why Aren`t There More Hydrofoils?
      Why Aren't There More Hydrofoils?!

      [16 Apr 98] After researching hydrofoils I conclude that they are far superior with respect to handling, performance, and comfort, than a normal displacing hull. So why then are they not used much anymore? In all my research I can only find one reason that sticks out: the foils can only be so big due to stress factors and drag. A huge ocean liner can carry much more than a hydrofoil, yet it is slower. Do you know of any other reasons, perhaps design drawbacks or facilities, the hydrofoil is becoming a prehistoric way of transport? -- Tristan Lee Andrews (tlandrew@learn.senecac.on.ca)
      [19 Apr 98] First, regarding size, the foil lifting capacity is an area function, increasing with the square of the speed. So in the practical speed range of 40 to 50 knots with the size of the hydrofoil craft increasing by a cubic function, the foil dimensions become relatively quite large. A Navy study concluded that a 2,000 ton hydrofoil was about a limiting size. Range is another consideration. Hydrofoils can be shown to compete commercially with aircraft up to about 300 miles on a time basis for downtown to downtown routes. This takes into consideration time to and from airports and the ability of the hydrofoil to go downtown to downtown. Hydrofoils have demonstrated their ability to provide superior rough water passenger comfort. So in adverse sea conditions, sea state three and above, their ride quality and speed are better than other high speed seacraft. The real problem is that hydrofoils have a high first cost on the basis of cost per seat mile. It has been determined that the acquisition cost is the driving factor in most acquisition decisions. To increase the use of commercial hydrofoils, studies that I have been involved with indicate that there is a market for small, 100 to 300 seat capacities, at speeds in the 40 to 50 knot speed range, with submerged foils and automatic control systems. But the first cost has to be made more attractive than available hydrofoils on the market today. I would like to see some concentrated design effort put into this area by a responsible designer and builder. ? Robert J. Johnston

      [18 Apr 98] I am also under the impression that interest in "the hydrofoil" is fading. Very few yards are pursing this concept. Rodriquez itself seems not to be interested in developing new ideas. Is there anything that can be done to foster a new breed of Hydrofoils? A few ideas: An agreement between IHS and Fast Ferry Magazine; Make available all studies carried out in the US on the field to all the interested parties via IHS web pages; Disseminate the hydrofoil ideas to all shipyards building fast ferries. -- Diego G. Mazzeo (diegomazzeo@tiscalinet.it).

      [21 Mar 98] I am trying to determine the possibilities and performance capabilities of using hydrofoil boats for personal yachting. I once rode on a trial craft that was to be utilized commercially in the Great Lakes (USA) but it never happened. This particular craft was about 60 feet long and was fast and smooth. -- Art Leo (dab1@flash.net)

      [21 Mar 98] I am presuming that you are speaking of motor yachts rather than sailing yachts. There are operating many hydrofoils of proven design operating in the size range you mention, though they are designed as ferries or tour boats. There are also several on the drawing boards waiting for someone to bankroll the detail design and development. I believe that one royal personage had a Boeing Jetfoil outfitted as a yacht in Saudi Arabia or a neighboring country. On a smaller scale, Harry T. Larsen, a Boeing employee, successfully added foils and an automatic control system to his Bayliner. Please spend some time exploring the links section of the IHS webs page. There is a South African and an Italian site that could interest you, also Harry Larsen's site. If you could provide any specifics on the nature of your interest... whether you are a the designer or the customer, areas in which the yacht is intended to operate, etc. that might help generate more useful info. -- Barney C. Black (webmaster@foils.org)
      [Date/Time=03-23-2002 - 12:49 AM]    Name:webmaster@foils.org [Msgid=237127]

    Polesye operators wanted!!
      Fast Flying Ferries is looking for operators who have polesye hydrofoils in their service. We have some question's on how to polisch the alloy foils.
      [Date/Time=04-24-2002 - 3:07 AM]    Name:Capt Mark van Rijzen dutchhydrofoils@wanadoo.nl, [Msgid=251014]

    Volga in the movies

    Largest Ever `Hydrofoil`
      The Soviet Babochka / Sokol military hydrofoil reportedly of 465 tons full load displacement is considered to be the largest hydrofoil type ever built. Scanning through an old issue of Hovering Craft and Hydrofoil journal (Volume 9, Number 2, November 1969) I found a photo of what must surely be the largest ever application of a ?hydrofoil? on a ship. I have included the photo as an attachment below. The text with the photo stated:

      "Hydrofoil provides launching ?lift?. This unusual appendage was fitted to the stern of the 43,000 tg [presumably Gross Tonnage] fishing parent and factory ship ?Vostok? for her launch from Admiraltisky yard, Leningrad. A hydrofoil strutted from a lattice after poppet structure provided a degree of lift prior to the buoyancy aft taking effect."

      Note: Hovering Craft and Hydrofoil is now published as Fast Ferry International

      [Date/Time=05-12-2002 - 7:02 AM]    Name:Martin Grimm seaflite@alphalink.com.au, [Msgid=258418]
      Attached File  "largefoil~JPG.zip" - size 91448   Click Here To Download

    Tidal Turbine Design Info Needed      ViewThread

      I am a mechanical engineering consultant currently operating in the area of gas turbine component manufacture. I have an interest in
      steering my future business towards the growing renewable energy industry, and for this end have an opportunity to become involved in the design of a 0.5 to 1.0 MW tidal turbine type project. I have designed and built a few small wind generators for college projects so have an appreciation for basic fluid dynamics, but having graduated from university in '85 and now because of a lack of practice, must admit my fluid dynamics expertise is rather 'rusty'.

      The design areas I am particularly interested in: hydrofoil profiles /
      lift / angle of attack / blade structural design - manufacture, dynamic similarity - modeling etc. I would appreciate your comments on this matter and look forward to hearing from you in the near future. -- Gene Hourihane, Rotamet Technologies Ltd., Ireland.
      [Date/Time=06-19-2002 - 7:57 PM]    Name:Gene Hourihane info@rotamet.com, [Msgid=273493]

    Tidal Turbine Design Info Needed
      Gene
      I know a few people who have adapted water pumps successfully to waterturbines to generate electricity off the grid at old Mills on rivers here in the US. The technology, to make these adaptions can be found on the Web at a number of Back-to-NATURE SITES.

      To get more technical you should check out the technology behind WATERJET Pumps. These have become very popular over the last 15 years and as a result there is a lot of information available. The large ones used for passenger and car ferries might be close to what you need. There are a number of design codes out there in two and three dimensions that should be able to help you.

      My experience was in the design of 40000 hp waterjet pumps for the US Navy's PHM Hydrofoils and Surface Effect Ships. They were all Very high speed two stage Mixed Flow devices similar to the the fuel pumps on NASA's Saturn 5 Appollo Moon rockets of the 60's/70's. You can find some usefull info still in the NASA Archives at their Web site.


      Best of luck
      Bill White


      [Date/Time=06-19-2002 - 11:25 PM]    Name:Bill White whitewn@speakeasy.net, [Msgid=273553]

    Tidal Turbine Design
      It's interesting to note that the premier waterjet designer and builder, KaMeWa (now part of Rolls-Royce, I think), began its existence in the mid-1800s as a manufacturer of water turbines to pump water for irrigation and other uses.
      [Date/Time=06-20-2002 - 7:43 AM]    Name:William Hockberger w.hockberger@verizon.net, [Msgid=273639]

    SES Super USA and Super Mexico      ViewThread
      Though they are not hydrofoils, I am looking for every kind of information about the Ulstein, Norway, built SES-Vessels "Super USA" and "Super Mexico", especially their current location and material condition.
      [Date/Time=06-29-2002 - 1:59 PM]    Name:C. Schramm c_schramm@t-online.de, [Msgid=276854]

    SES Super USA and Super Mexico
      C. Schramm

      I can.t help on these two vessels, but I know that there are people here who can answer your questions. There are experts in all kinds of advanced vehicles here, so feel encouraged to use this section of the Bulletin Board to talk about all kinds of craft.

      Bill White
      [Date/Time=06-29-2002 - 7:15 PM]    Name:Bill White whitewn@speakeasy.net, [Msgid=276916]

    Ekranoplan Consultant Wanted      ViewThread
      I am much interested in Ekranoplan. For further understand and commercial industry in the Korea. I wish to contact with a consultant regarding Ekranoplan. If you could please assist me. Thank you. 
      
      

      [Date/Time=08-16-2002 - 8:09 AM]    Name:Kunkiw Lee treeson62@hotmail.com, [Msgid=296625]

    Power Generation from Hydrofoils
      A little update, the maths are far better that my old figures. The mechanical /time /foil lift and drag/advantages stay around the same +_120... it's the density and slip factors that are the trouble. We know that we have to start with 840x that of air/water density, I have the approx. sums that rotating water foil turbines get. But I still don't think anyone knows this. Ours will be much higher and constant. I still think only test tanks will show this very high figure. The working film is starting to look fantastic. But it's a lot of work for our web team (Florain and dad) to show the world it is feasible to get all the RE you want from Old Man River and Mrs Tide. Who needs expensive dams when you can have energy from the flow all the way to the sea, and then you still have even more at about ^60% Tide. Full article in AYRS London, Catalyst magazine, summer 02.


      [Date/Time=08-18-2002 - 12:49 PM]    Name:Ken Upton ken@cyberlifeboat.org, [Msgid=297585]

    Asymetrical Leeboards Sail Canoe      ViewThread
      I have been sailing/racing a sail canoe for several years. Most sail canoe skippers use a single leeboard.

      I'm curious as to how much my canoe's windward performance could be improved by using a pair of asymmetrical leeboards, one at a time on each tack.

      Given a top speed of 4 knots to windward, and leeboard underwater dimensions of about 3 ft long by about 8 inches wide, what asymmetrical cross-section would be best: ie what max thickness, what front-to-back location of the max chord height, and is blunt entry better than sharp entry for the leading edge?

      Does anyone have any sketches showing optimum cross-section for selected velocities thru the water at the 1-6 knot range? Would cavitation cause problems at this low a velocity?
      [Date/Time=11-22-2002 - 4:42 PM]    Name:Dan Reiber danreiber@adelphia.net, [Msgid=342085]

    Asymetrical Leeboards Sail Canoe
      I learned to sail by rigging our canoe for sail and making my own leeboards. I never got around to making a rudder - just steered with the paddle. My leeboards were asymmetrical, carved by eye. Today I'd use XFOIL to design a custom section and make templates to accurately profile the shape. Still, my canoe literally sailed circles around the Sunflower from which I got the sail rig.

      ...what asymmetrical cross-section would be best? ...is blunt entry better than sharp entry for the leading edge?

      You want to shape the leading edge as accurately as possible to the
      coordinates of your chosen section. The right leading edge shape is neither blunt nor sharp. It's one of those Goldilocks things. It's better to be just right.

      You might want to try one of Selig's model glider airfoils, like the S7012 http://www.nasg.com/afdb/show-airfoil-e.phtml?id=1055 or the S7075 http://www.nasg.com/afdb/show-airfoil-e.phtml?id=1057. They are intended to work well at low speeds.

      Don't forget that the deeper you make your boards, the less drag due to lift there will be.

      ...the 1-6 knot range... Would cavitation cause problems at this low a velocity?

      The foil will stall before you reach cavitation. You got no worries about cavitation with a canoe.

      [Date/Time=11-23-2002 - 5:49 AM]    Name:Tom Speer me@tspeer.com, [Msgid=342291]

    WIG aircraft - are they AMVs?      ViewThread
      Should ekranoplans be considered as members of the category of Advanced Marine Vehicles (AMVs)? If so, the IHS should endeavor to locate technical information and make it available on the AMV CD-ROMs it is preparing.
      [Date/Time=12-04-2002 - 6:49 PM]    Name:Barney C Black webmaster@foils.org, [Msgid=346886]

    WIG aircraft - are they AMVs?
      My own view is that ekranoplans are definitely AMVs. Although they cruise entirely above the surface of the water (at least they intend to, and there's a problem if they don't quite succeed), they derive their good performance from being close to that surface. They could cruise above a land surface, too, but landing would then become more of a concern, as most have been designed to land and take off from water. By being designed for best performance close to the surface, ekranoplans give up good performance away from it. Some can climb up to considerable altitude, but they make poor airplanes and are very inefficient there. It's a good capability for climbing above a bridge or a ship or jumping from a lake to a bay or something, but you wouldn't want to have to pay for a lot of operation in that manner.

      When the Soviet engineers were doing so much to develop ekranoplan technology, they designed them to be built in shipyards using high performance marine vehicle materials and processes, rather than in aircraft production facilities. They have to be able to live in a marine environment and to take a certain amount of pounding when landing and taking off, as well as minor wave impacts while flying. (Seaplanes have to endure much of the same, but they also have to be good airplanes and fly efficiently at altitude, so they're properly built in aviation facilities.)

      I don't know of any focused consideration by our own Coast Guard and aviation regulators to sort this issue out, but I think it has been carried further in certain foreign areas, where ekranoplans have appeared to be nearer to actual use. I think Australia is one such, probably Russia, maybe Germany?
      [Date/Time=12-04-2002 - 6:52 PM]    Name:Bill Hockberger w.hockberger@verizon.net, [Msgid=346887]

    Special Event Vendors?      ViewThread
      Hi, I help organize Aerospace America International Airshow, June 13-14-15, 2003, at Will Rogers World Airport, Oklahoma City. A few years back, about 1993, I attended a hot air balloon fest in Middletown, Ohio (or it might have been Battle Creek in '94) ... anyway, someone there had a hydrofoil used as a "ride," driving it around in a grassy field. It was not overly expensive for passengers but it got a LOT of interest. Is anyone aware of such a vendor still doing this? I would like to be in touch regarding our event -- audience expected 85,000 to 100,000. Airshow office phone: 405-685-9546 or fax: 405-695-9567. Email: SkymarketOKC@aol.com Attn: Betsy Fry. Oklahoma City is home to Tinker Air Force base, and more.
      [Date/Time=02-10-2003 - 9:54 PM]    Name:Betsy Fry Skymarketokc@aol.com, [Msgid=375871]

    Re; Special Event Vendors?
      Hello Betsy,

      Sounds like your intriguing "hydrofoil ride over the grass" was probably a small hovercraft instead!There might be a hovercraft association or club in your neck of the woods that can help if you can't find the original vendor.Good luck.Garry Fry,I'm in Australia,no relation that I'm aware of!


      [Date/Time=02-11-2003 - 8:53 AM]    Name:Garry Fry gfry@vtown.com.au, [Msgid=376077]

    Re; Special Event Vendors?
      Could this have been a hovercraft--a vehicle that rides on a cushion of low pressure air?

      It is difficult to imagine how the underwater wings of a hydrofoil could function on a grassy field. You may need to redefine your question.
      [Date/Time=02-11-2003 - 8:50 PM]    Name:Ray Vellinga rvelll@hotmail.com, [Msgid=376506]

    Re; Re; Special Event Vendors?
      Hovercraft! Once you folks got me pointed in the right direction, things have worked out nicely. I found a hovercraft distributor who has a dealer in our state. They are going to display a 10 man model ideal for search and rescue in these parts (we have A LOT of police and emergency personnel at the Airshow). Not only that, they'll do the rides I was wondering about.
      And I've learned the difference between a hydrofoil and a hovercraft! Thank you very much!!!

      Betsy
      [Date/Time=02-12-2003 - 8:54 AM]    Name:Betsy Fry SkyMarketOKC@aol.com, [Msgid=376791]

    Help with a dynafoil      ViewThread
      I recently aquired a Dynafoil by Hydrocraft (a jet ski size hydrofoil build around 1970) it is in good shape but the fuel pump doesn't work I was wondering if anybody knew anything about this particular hydrofoil or even knows where to get parts for one.
      If any one has information please call me.

      Jonathan Javetz at:
      706 714 4903
      thank you
      [Date/Time=05-30-2003 - 1:52 PM]    Name:Jonathan Javetz schwartz1101@cs.com, [Msgid=444435]

    Re; Help with a dynafoil
      Rebuild kits are available for the injectors on the Dynafoils, but I need to know which size engine you have, the 440 or the 340. It can also be refitted with dual Mikunis for a rated HP of 55, but not necessary to have the extra HP.
      [Date/Time=06-05-2003 - 6:27 AM]    Name:Scott Smith ssmith@syntheon.com, [Msgid=447373]

    Hydrobowl and HPC Watercraft Symposium
      Friday October 24, 2003
      2003 HP Symposium Series:
      Human Powered Hybrids - Taking advantage of the surrounding environment
      A Panel Discussion
      Paul MacCready, Jake Free and Sid Shutt
      Calif State Univ Long Beach Noon to 3 pm

      Saturday October 25, 2003
      Hydrobowl - $30.00 per boat entry fee. Free to spectators
      100 meter flying start sprint
      100 meter 10 pin slalom
      2000 meter criterium
      static thrust
      LB Marine Stadium, 8am-12noon

      HPV day at the Encino Velodrome on Sunday the 26th
      Contact Carole Leone, traslo@fix.net

      2003 HP Symposium Series:
      Propeller Design for low power, high efficency
      4 Sessions & Panel Discussion
      Jake Free, Bill Patterson, Sid Shutt, Jack Norris and Andy Bauer
      Monday October 27 at CSULB. Noon-4

      Contact:

      Bill Gaines
      714-744-8439 (eve) 714-403-5053 (cell) 626-812-2199 (m-f,7-3)
      william.gaines@NGC.com (days)gainesw@aol.com (once a week)

      HUMAN POWERED HYBRIDS:
      Taking advantage of the surrounding environment

      In the design of low or limited power systems energy utilization is critical. Clearly the direct energy source needs to be highly efficent. Indirect energy sources can be siginificantly exploited, and at times even exceed the contribution of the direct source(s). This Panel discussion will explore these issues and their application to human powered vehicles.

      Some of the indirect sources that will be exploried are:
      Sails, Kites, Special Propellers/Windmills, Solar Power, Surfing, Soaring on updrafts, as well as correctly riding water currents eddies and rip tides taking advantage of turbulances

      Panel speakers = Paul MacCready, Sid Shutt, Jake Free

      ******************************************************
      Propeller Design Individual sessions: Between 12:00 and 4:00 ET (Engineering Technology) Building at Long Beach State University

      Jake Free: independently developed basic thoeries and advanced "Analogy" theories (marine)

      Bill Patterson: helocopter applications of air propeller as well as "Minimum induced loss" (circulation) throries of Larribbee (air)

      Andy Bauer and Jack Norris: Efficiency theories based on Theodorsen: "Minimum induced and minimum profile drag propellers made understandable" (especially air)

      Sid Shutt: Taking characteristic LD curves/properties through to the build (including Reynolds integral); Proceeding from calculations to evaluating the result (primarily marine)


      *****************

      Propeller Panel Discussion "questions" to each method; motion to static thrust/helocopter / hovercraft? Similarities and differences of air and water propellers: sections, geometry, others

      Speaker Biographies:
      Paul MacCready: Paul has an academic background in Physics and Aeronautics and pioneered the use of instrumented sailplanes and powered aircraft in atmospheric measurements. He has won noumerous national soaring championships. The techniques he develpoed are standards used by pilots everywhere. His design of the ultra-light flight vehicles, Gossamer Condor, Albatross, solar powered Penguin, Bionic Bat, Solar Challenger and Helios expand the concept of the motto Do more with less. His work in recreating the giant pterodactyle featured in the IMAX movie On the Wing explored the earliest evolution of Earthling flight and its need to make use of the surrounding energy.

      Sid Shutt- built the HYDROPED series which was the worlds second human powered hydrofoil to fly behind the Flying Fish. During the early years, the Hydroped and Flying Fish went back and fourth as keeper of the world speed records and DuPont Prize attempts. Hydroped was the first human powered hydrofoil to take off from the water. Along with being a pioneer in hydrofoil sailboats, Sid is without a doubt the worlds formost authority on designing and building human powered hydrofoil propellers!

      Bill Patterson: Through being a professor at CalPoly, Bill and his students were the first humans to fly a human powered helocopter DaVinci III. They used minimum induced loss Larribee techniques for the propellers that powered the rotors for the 'copter. The roters themselves should also present a good perspective on human powered propellers!

      Jack Norris and Andy Bauer: From being glider/sailplane champions to being tecnical director for the Voyager Aircraft Project (you know, the one that flew around the world on a single tank of gas?). Norris and Bauer will present efficiency theories, "Minimum induced and profile drag made understandable" based on Theodorsen.

      Jake Free: Since 1985 after hundreds of propeller designs and thousands of installations including those for HP hydrofoils, displacement boats, single and multi seat, kinetic sculptures, submarines, (with first places too numerous to mention) his formulas and algorhythoms have been anathama to the public. In this presentation he will show techniques ranging from a :30 second estimate to a full-blown world class build using his own "analogy" theory.

      The contact for details is Bill Gaines at GAINESW@aol.com
      [Date/Time=10-03-2003 - 4:36 AM]    Name:Bill Gaines GAINESW@aol.com, [Msgid=518983]

    Hamilton Walker and Dynaplane Info      ViewThread
      I have been looking for a foil-supported craft called the Cushion Craft built by a guy called Hamilton Walker and also a boat called the dynaplane. Can you help?
      [Date/Time=10-21-2003 - 8:35 PM]    Name:Waqas Kamran Ahmad waqas@ahmad1995.fsnet.co.uk, [Msgid=529463]

    Re; Hamilton Walker and Dynaplane Info
      "Dynaplane" is a term, originated by E.P. Clement of DART Marine Consultants in the 1960s, I believe, that describes a stepped planing hull with stern stabilizers. If you have access to a library with naval architecture materials, you may be able to find a copy of E.P. Clement's article written with D.H. Desty entitled The BP Dynaplane High Speed Research Boat. Also, I found with a key word search that there is an article by Wallace Cloud in the September 1968 issue of Popular Science Magazine titled New Dynaplane: Twice the Speed on Half.... You can find old copies of magazines for sale on the eBay website, or you can get copies of Popular Science articles from John Muxlow (contact him at jj.muxlow@ns.sympatico.ca)
      [Date/Time=10-25-2003 - 7:45 PM]    Name:Barney C Black webmaster@foils.org, [Msgid=532301]

    Re; Hamilton Walker and Dynaplane Inf
      "Cushion Craft" was also the name given to a series of smaller Air Cushion Vehicles (ACV's) or hovercraft. Is it possible that these may be the craft you have in mind? They would not have had any foil support however.
      [Date/Time=11-28-2003 - 9:51 AM]    Name:Martin Grimm seaflite@alphalink.com.au, [Msgid=551215]

    supercavitating spoiler      ViewThread
      I am a french student working about supercavitation. I am looking for any information about a process which allows to increase lift a gives a better seakeeping and stability, by reducing motions. It is a little cavitating spoiler put at the trailing edge, also called interceptor.
      I would like to have informations about the aplications of this process.
      Thank you
      [Date/Time=04-01-2004 - 12:08 PM]    Name:Ga? Jouannic Gael.jouannic@caramail.com, [Msgid=624747]

    Re; supercavitating spoiler
      Ga?

      Most interceptors installed on ships are really not supercavitating at all.

      A good source of information is the company Maritime Dynamics. They have designed and installed many interceptors worlwide. Their web site is at

      http://www.maritimedynamics.com/products/interceptors.htm

      They operate by changing the vertical pressure on the rear of the hull in front of the interceptors. This pressure change is caused by the interceptors blocking the flow of the boundary layer flow over the hull.



      [Date/Time=04-01-2004 - 7:15 PM]    Name:Bill White whitewn@speakeasy.net, [Msgid=625025]

    Re; Re; supercavitating spoiler
      Many thanks for your answer and the link you gave.
      Yet I am still sure it exist cavitating spoiler put on the trailing edge of a foil: I am now studying it in Russia where it seems to be known for 30 years. But I miss information concerning their applications.
      [Date/Time=04-02-2004 - 4:57 AM]    Name:Ga? Jouannic Gael.jouannic@caramail.com, [Msgid=625227]

    Re; supercavitating spoiler
      The Russians were apparently developing torpedo designs which operated in a supercavitating mode through the use of a particular nose shape that promoted a vapour cavity over the aft portion of the torpedo. This may have had a wedge or step to trigger the cavity aft of the nose.

      Supramar AG in Switzerland has also been researching the use of foil profiles with a groove that promotes (or prevents?) supercavitating flow. I don't know if that was also intended to serve as a means of motion control. Some information about this work is on the Supramar website:

      http://www.supramar.ch/
      [Date/Time=04-15-2004 - 12:19 AM]    Name:Martin Grimm seaflite@alphalink.com.au, [Msgid=631273]

    Re; Re; supercavitating spoiler
      Gael, Martin

      Martin, I can confirm your memory on Russian supercav torpedoes that used sharp edges on the nose to form a vapor cavity over the rest of the body to minimise skin friction drag and play with the boundary layer flow. You can find non technical papers on the subject in various hydrodynamic society papers over the last fifeteen years.

      The US Navy has utilised the basic technology successfully on several projects over the years. But I am not aware of any published information on the subject.

      I also have never heard the term "interceptor" used with the technology in this country though.

      Best Wishes
      Bill White
      [Date/Time=04-16-2004 - 6:35 PM]    Name:Bill White whitewn@speakeasy.net, [Msgid=632302]

    Re; Re; supercavitating spoiler
      I would classify an inceptor as a Gurney flap for the hull. You might be able to apply research on airfoils with Gurney flaps to the maritime application. Also look for research on divergent trailing edges. Given the flow separation ahead of the inceptor, it really acts like a wedge. Personally, it seems like anything you could do with an inceptor you could do more efficiently with a flap, but I suppose there are some issues of mechanization that make the inceptor attractive.

      I agree it's not supercavitating - it's ventilated. The gas behind it is air, not water vapor.
      [Date/Time=04-18-2004 - 7:20 PM]    Name:Tom Speer me@tspeer.com, [Msgid=633026]

    Re; Re; Re; supercavitating spoiler
      BILL, We had an Anti-torpedo torpedo program under BTI. Totally successful, but cancelled when BTI went.
      Respy, NAT K
      [Date/Time=04-20-2004 - 10:33 AM]    Name:NAT KOBITZ KOBITZN@CTCGSC.ORG, [Msgid=633856]


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