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US20050172881A1 - Transonic hull and hydrofield (part III-A) - Google Patents

Transonic hull and hydrofield (part III-A) Download PDF

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Publication number
US20050172881A1
US20050172881A1 US10/774,728 US77472804A US2005172881A1 US 20050172881 A1 US20050172881 A1 US 20050172881A1 US 77472804 A US77472804 A US 77472804A US 2005172881 A1 US2005172881 A1 US 2005172881A1
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hull
speed
lateral
drag
hulls
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Alberto Alvarez-Calderon F.
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Individual
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Priority to US10/774,728 priority Critical patent/US20050172881A1/en
Priority to EP05711645.1A priority patent/EP1718518B1/fr
Priority to AU2005212216A priority patent/AU2005212216A1/en
Priority to PCT/US2005/001662 priority patent/WO2005077745A1/fr
Priority to CNA2005800108937A priority patent/CN101052561A/zh
Publication of US20050172881A1 publication Critical patent/US20050172881A1/en
Priority to US11/502,326 priority patent/US20070107646A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/32—Other means for varying the inherent hydrodynamic characteristics of hulls
    • B63B1/40—Other means for varying the inherent hydrodynamic characteristics of hulls by diminishing wave resistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
    • B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
    • B63B1/14—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected resiliently or having means for actively varying hull shape or configuration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
    • B63B1/18—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydroplane type
    • B63B1/20—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydroplane type having more than one planing surface
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T70/00—Maritime or waterways transport
    • Y02T70/10—Measures concerning design or construction of watercraft hulls

Definitions

  • the present invention specifies new unique design shapes, features, and methods of operation which qualitatively improve and extend the scope of the transonic hull TH and the transonic hydrofield TH inventions of patent application Ser. Nos. 08/814,418 and 08/814,017.
  • the scope of the present invention is summarized below:
  • the new invention is an all weather stealth transonic hull capable of operating in new high speed hydrofield regimes of the transonic hull, which now includes the hypercritical, transplanar, and X regimes.
  • the hull of the present invention is also referred to in certain important cases as TH-II, and its broadened hydrofield is TH-II.
  • Other embodiments of the present invention are improvements applicable to TH and TH-II.
  • FIGS. 1, 2 , 3 and 4 are examples of the prior art related to this invention; are views of the cover planform and profile view of TH, and planview of TH of the present invention;
  • FIGS. 5, 7 a, 7 b, 9 , 10 , 11 , 12 a, 12 b and 14 f cover examples shown in previously filed application Ser. No. 08/814,418;
  • FIG. 8 specifies the relation between drag and V/ ⁇ square root ⁇ L for TH and IACC hulls
  • FIGS. 13 a and 13 b disclose the TH-II and TH-II in hypercritical regime
  • FIGS. 14 a and 14 b disclose the TH-II and TH-II in transplanar regime
  • FIGS. 14 c and 14 d disclose the stern profile and flap
  • FIG. 14 e discloses the combination of the stern flap and profile thereof
  • FIG. 15 discloses the TH-II and TH-II in X-regime
  • FIG. 16 discloses the stern and side flap for control
  • FIG. 17 discloses the TH and TH in sea waves with lateral flaps for control
  • FIGS. 18 a - g disclose the TH 3-D shape for operation in adverse seas and stealth operation
  • FIGS. 19-28 c disclose further embodiments and structures associated with the TH and TH of the present invention.
  • FIGS. 29-49 disclose further additional embodiments and structures associated with the TH and TH of the present invention.
  • Displacement hulls sustain boat weight by buoyant lift. As designed in the past and present, they have an upper speed limit called “hull speed,” near and above which hydrodynamic resistance (drag) grows at a high exponential rate, for example, as in FIG. 1 .
  • the “hull speed” occurs when the length between bow and stern waves generated by and traveling with the translating hull equals the geometric length of the hull. This situation is expressed numerically when the ratio of boat speed in knots divided by square root of boat length in feet equals 1.34.
  • Displacement hulls are very efficient well below hull speeds with weight-to-drag ratio of over 100. At extremely low speeds, the efficiency ratio increases to much higher values, because drag approaches zero but weight remains constant. However, near or above hull speed, their weight-to-drag ratio decreases rapidly and becomes physically and economically unacceptable. Therefore, higher speeds of displacement hulls is attainable principally by increasing hull length. Unfortunately, the speed advantage of length is not large. For example, the nominal “hull speed” of a 50 foot hull is 9.5 knots, but for 300 foot hull speed, it is only 23 knots.
  • the “hull speed” limit is intrinsic of displacement hulls, because of their wave generation properties as they translate in the water, i.e., “wave making.”
  • the length of waves generated by the hull exceed the geometric length of the hull, as shown in FIG. 2 , the situation becomes critical.
  • the increasing size of bow wave with increasing speed induces a further drop of the trough near midbody, leading to incremental sinkage of the hull and an increase of hull's angle of attack.
  • the increase of angle of attack impedes further speed increase unless very large power is available to climb over the bow wave and enter the planing regime, the limitations of which will be discussed later on.
  • the principal characteristics of displacement hulls which cause and determine their maximum operational speed envelopes are available in various sources (for example, “A Comparative Evaluation of Novel Ship Types,” by MIT's Professor Philip Mandel) and is summarized on the left side of FIGS. 3 and 4 .
  • the operational speed envelope covers speed-to-length ratios of 0.8 to about 1.0 or 1.1 for commercial ships, which is well below their “hull speeds” of 1.34.
  • Military ships have speed envelopes that include “hull speed” (for example, a cruiser ship at 1.35) and even above “hull speed” (for example, the slender destroyer operating at speed-to-length ratio of about 1.7). Above the speed ratios described, the required size and weight of conventional power plants and hydrodynamic problems of propulsion at the lower weight-to-drag ratios become unacceptable for the missions of the ships.
  • planing hull in which weight is supported by a hydrodynamic lift force from momentum change (as distinct from buoyant lift), can overcome the speed limits of displacement hulls, and furthermore that they are efficient at high speed.
  • planing permits high boat speed, it does so only for boats with an approximately flat underbody having relatively light weight and equipped with large propulsive thrust.
  • the limiting characteristics of this hull is the presence of dynamic drag due to momentum change, shown in FIG. 5 for the limiting case of inviscid planing. In practice, these hulls operate at angles of attack of 3° to 6°.
  • the inviscid weight-to-drag ratio for optimum flat plate planing case is 19 and 9.5 respectively.
  • planing hulls are best exemplified by the ski boats and similar sports craft which below their planing speeds (for example, below a speed-to-length ratio of about 4) require a nose-high attitude with large wave-making drag in displacement mode, a condition similar to that shown for the lowest but longer hull in FIG. 2 .
  • displacement hulls cover an operational speed-to-length envelope from about 0.8 to 1.8, in which the weight-to-drag ratio decreases smoothly from over 120 (higher for slow tankers) to about 25, which the corresponding volumetric coefficient decreasing smoothly from about 80 (higher for slow tankers) to about 55 for destroyers.
  • planing hulls have an operational speed-to-length ratio of the order of 3 to well above 4 ( FIG. 3 ), but with weight-to-drag ratios of about 6-8, and with a volumetric coefficient of above 100 ( FIG. 4 ), which is evidently much higher than displacement hulls only because the latter are much longer.
  • the higher volumetric coefficient reflects the fact that planing designs are not intended for nor are capable of sustained operation near or below “hull speed” in which their low weight-to-drag ratio would be prohibitive compared to displacement hulls.
  • the displacement hull has a wave-making drag component which increases strongly with speed near and above hull speed, in addition to an approximately constant wetted area generating friction drag which increases roughly with square of speed.
  • These drag sources combine into a high total exponential drag growth near and above “hull speed” which was shown in FIG. 1 .
  • operational speed-to-length ratios are about one for commercial ships and somewhat below two for military ships.
  • the percent distribution of frictional resistance and wave-making resistance is shown in FIG. 6 . It shows that above “hull speed” of 1.34 more than 60% of resistance is residuary—mostly wave making drag.
  • the semi-planing hull Unlike displacement hulls which have upwardly curved sterns and curvatures at the bow, causing suction which sinks their center of gravity with forward speed (increasing their apparent weight), and unlike planing hulls having mostly flat undersurfaces and a CG which tends to rise with forward speed, the semi-planing hull usually has a Vee bottom and, for practical reasons, is heavier than a pure planing hull. Although the semi-planing hulls can generate the appearance of a “flat” wake at high speeds, their lift is generated by a combination of buoyancy and dynamic forces, which is inherently inefficient. These hybrids are longer and have lower volumetric coefficient compared to those of planing hulls, but are nevertheless much higher than for displacement hulls, as shown, for example, at the middle of FIG. 4 .
  • the conventional semi-planing hull is an inefficient hybrid: at slow speeds, it has excessive drag compared to a good displacement hull. It requires very large power to reach semi-planing speed, at which regime it is not as fast and is less efficient than a pure planing hull.
  • a deep-vee semi-planing hull provides smoother ride for a greater payload in a rough sea, and is more seaworthy than a planing hull.
  • it has a rougher ride than a displacement hull, with less favorable sea keeping characteristics, and is commercially not viable for most large maritime applications.
  • Trimarans may have similar characteristics with some structural gains, and they also have large traditional buoyancy reserves forward, but only on the center hull.
  • Recent multihull trends are exploring trimarans with a very long displacement center hull to retain a low speed-to-length ratio of the center hull, with small, narrow, lateral hulls at high speed-to-length ratio for roll stability, and to support a wide deck.
  • Wave-piercing multihulls may have a center body which has water contact only in swells, providing the usual large buoyancy reserves in adverse seas, but permitting wave piercing in middle seas.
  • SWATHS are also multihulls which rely on totally submerged primary displacement for smooth riding, with penalties in wetted area and speed.
  • the TH is characterized in having a submerged portion with a triangular waterplane shape with apex forward in static and in dynamic conditions, a triangular profile, or modified triangular profile in side view with maximum draft forward and minimum draft aft, and planar lateral surfaces at large inclination or vertical to the water.
  • the submerged portion has a double-wedge volume distribution with a fine narrow entry angle in planview and a fine exit angle aft in profile view.
  • TH shape of TH, and its associated hydrofield TH, is characterized in absence of surface wave-making sources such as shoulder, midbody, or quarter curvatures in planview; they have a narrow entry forward which minimizes the water volume displaced per unit of time, and induces special inboard underbody flow, favoring flow subduction which eliminates the conventional wave-making pattern of displacement hulls, and allows for new types of hydrodyamic ray phenomenon of very reduced size and an absence of midbody trough.
  • surface wave-making sources such as shoulder, midbody, or quarter curvatures in planview
  • TH has a favorable anti-planing propulsive pressure component at its undersurface; favorable contracting streamline on the sides; favorable gravitational pressure gradients on the hull's lower surface; broad stern underflow which prevents pitch up and eliminate stern wave, and favors the recovery of underbody energy as well as that from following seas.
  • TH and TH as specified in my prior patent application Ser. No. 08/814,418 is the elimination of the below-water wave-making sources for high speed operation in calm water within its displacement mode, thus preventing or reducing the high exponential rise of wave-making drag which characterizes conventional hulls near and above their “hull speed.”
  • nominal “hull speed” is 1.34 when expressed with speeds in knots divided by square root of boat length in feet. In this speed range, for example as in FIG.
  • the wave drag component of total drag of conventional hulls grows significantly, and hence the total drag grows in a high exponential manner, typically by powers of the order of three or more, depending on hull shape, beam loadings, and Froude number range (Froude number is defined as speed in Ft./Sec. divided by the square root of gravity acceleration times engaged water line length in feet).
  • TH's principal remaining source of drag growth with speed is that due to friction, it being noted that (a) TH has no pressure drag problems at the stern since it has a clean water exit, and (b) TH has greatly reduced form drag, because it has no curved surface to significantly increase local and therefore average dynamic pressure along its wetted surfaces.
  • Curves from tow tank test of a TH archetype model are shown in FIG. 8 of the present Application, showing that, in the supercritical regime, which begins at about the speed corresponding to the critical hull speed of a conventional displacement hull, TH's total drag grows substantially with second power of speed above “hull speed,” within the speed limits of the test, during which hull's pitch angle had no significant change, and bottom and side wetted surface was observed to have no substantial change.
  • the drag growth to the second power can only occur in the absence of growth of wave-making drag within that speed range.
  • the critical speed of a conventional hull occurs when the length between the bow wave and its corresponding stern wave is equal to hull's waterline length, and this occurs at a ratio of speed in knots to quare root of length in feet of 1.35.
  • the test data of FIG. 8 indicates that the IACC hull has 40% more drag than the TH archetype at a speed-to-length ratio of about 1.55, and 28% more drag at a speed-to-length ratio of about 1.75. Due to speed limits of carriage, tests of TH model could not investigate hydrofields at speed/length ratio greater than about 1.8.
  • the initial design speed to be selected for the square speed growth of TH's total drag depends on TH's shape and on its ratio of boat weight to cube of hull length, and can be lower than the 1.35 shown in FIG. 7 , for example, by changing the angle in planview of the sides of TH or changing the weight. For example, a 20% weight reduction lowered the starting speed/length ratio of TH's supercritical speed regime to 1.1, above which drag growth follows only the second power of speed.
  • FIGS. 3 and 4 which shows that three different types of optimized conventional hulls, having well-known hydrodynamic regimes such as displacement, semi-displacement, and planing, are required to operate in calm water in a speed-to-length envelope of less than 1 to greater than 5, is it possible to design a single hull capable of operating in that broad speed envelope?
  • the single new hull type is established, for example, as in the present TH-II and TH-II invention, capable of operating over the broad speed range currently requiring two or three different hull types, each optimized in over 100 years of development, could that new hull type have penalties in speed and weight in an adverse sea which are larger than the penalties suffered by the three types of hulls optimized also for adverse seas in their respective speed envelopes, or could the penalties for the new hull be less severe, or perhaps mostly eliminated?
  • the writer first considers the supercritical regime with absence of wave-making drag growth with speed. There has to remain drag growth with speed of viscous origin, imperfectly referred to as friction drag, which for a given hull size grows necessarily with the second power of speed. Hence, there could be encountered practical limits due to due to powerplant size requirements, weight and costs which occur because power is a cube function of speed growth, even if drag growth of TH is a second power of speed, since power equals drag times velocity.
  • the quasi-constant magnitude of propulsive pressure force component of TH is a problem of significance for TH's overall power requirement, which is illustrated below with a specific example:
  • the dynamic pressure based on remote speed is 2,879 lb/ft 2 .
  • the friction drag term D for the weight-to-total-drag ratio at higher speed-to-length ratio reaches very high values under enormous remote dynamic pressure q.
  • the weight-to-drag ratio of the assumed TH archetype decreases and could be as low as that of a planing hull, about 8 or less for the example analyzed.
  • the propulsive pressure force on the lower surface of TH which is important in the displacement mode near “hull speed” and necessarily a function of the apparent weight of TH and the sine of the negative angle ⁇ of TH's lower surface, becomes less and less significant as percentage of total propulsive thrust needed to overcome drag as speed increases, since the viscous drag, which total thrust must overcome, continues to grow with the square of speed at constant wetted area, whereas changes of weight with speed, even considering apparent weight increases under subduction flows at high dynamic pressure, and therefore of net propulsive underbody pressure forces, are obviously not as significant.
  • This speed regime is shown in FIG. 11 , in which surface flow fields of TH are approximately flat in region 11 . But undersurface viscosity forces, relative to momentum content of flow at subcritical speeds, limits the shape and area of the wake at 11 to a gothic arch type with aft border 11 . Rays 13 and 15 have larger humps. Downstream of flat wake 11 , there is some eddy and hump formations 17 and a central hump 21 . In this sub-critical regime, there may be in some cases drag growth with speed higher than second power of speed, because of the eddies and elevations, even though for TH there are no transverse stern wave nor a bow wave of the type of conventional displacement hulls.
  • the regime is uniquely efficient and to a critical measure a unique property of the special triangular planform of TH, and its profile, under effect of higher levels to achieve the higher dynamic pressure in hypercritical regime, as will be described later on in greater detail with aid of FIG. 13 .
  • the undersurface has a negative angle ⁇ establishing a draft at the bow much larger than at the stern.
  • the new regime is named “hypercritical,” and was attained with propulsive thrust approximately parallel and below the undersurface located as in prop shaft 33 to provide nose up pitch up couple with respect to TH-II's drag with arm 37 of approximately 0.5 units (0.007% LOA).
  • thrust line is inclined upward as in prop shaft 35 , it can provide a lifting force equal to thrust times sine of angle 39 . For example, if weight-to-drag ratio were 75, drag would be W/75 and a 10° angle at 39 would result in a lift force of 0.0024W.
  • the specifications for FIG. 13 b differs from and is improved in respect to FIG. 12 b as follows: large change of angle of undersurface from ⁇ to ⁇ 1 ; a large reduction of bow draft from approximately length 26 to a much smaller value 38 ; a substantial reduction of lateral wetted area and of propulsive pressure on the undersurface, an increase of dynamic pressures and momentum content on the wake, and an aft shift of center of gravity, combined with certain effects of thrust line in this case from propeller but could be water jets as well.
  • the complex combined action of the changes above produce the hypercritical regime and results in greatly improved weight-to-drag ratio for speed/length ratio of order of 3, or more, that is, in the range usually assigned to larger vee-bottom semi-planing boats.
  • TH-II now operates in three regimes: subcritical, supercritical, and hypercritical, and prevents a wake with a significantly depressed surface.
  • FIG. 13 b The above description of FIG. 13 b is feasible for and unique to the TH configuration because its flat sides are devoid of shoulder, mid-body, and quarter curvatures which are usual wave-making sources, and because the maximum beam of TH is adjacent the stern, and therefore collects the entire underbody momentum flows and discharges it in flat exit wake with high momentum content which continues to prevent transverse stern wave formation.
  • FIG. 13 b A word of caution in respect to FIG. 13 b is the limit of center of gravity shift to the rear, since it has to meet both supercritical and hypercritical regimes. Wrong choice can produce a tendency for self-sustained pitch oscillations similar to an aircraft “phugoid” mode, which can become unstable and divergent. The CG location for FIG. 13 b requires certain limits, reviewed later on.
  • TH-II of FIG. 14 is shown in its transplanar regime in profile in FIG. 14 b and in planview in FIG. 14 a.
  • the contrasts and large benefits of TH-II's transplanar regime are evident in the following description:
  • FIG. 14 a shows in planform a transonic hull having its archetype triangular shape, similar to that of FIGS. 10 and 11 .
  • the hydrodynamic regime in FIG. 14 a is entirely different from FIG. 12 , and also different from conventional planing hull.
  • the hull is at a very small positive angle ⁇ 11 , shown with numeral 65 , with a wetted length 61 and a dry length 67 .
  • the dry area 69 is considerably smaller than 61 , which greatly reduces slamming loads in an adverse sea.
  • volume above length 69 is much smaller than above length 67 , reducing added buoyant forces in an adverse sea.
  • surface of wake shows a unique absence of lateral spray, indeed retaining lateral rays of the type of FIG. 10 , which is contrary to, and not possible in, conventional planing hull.
  • TH center of gravity
  • LCF longitudinal center of flotation
  • thrust line thrust line
  • the center of gravity needed to meet the required conditions in transplanar flow depend on hull shape in planform in profile, and thrust line location.
  • a good value for CG location for the above example is 28 units measured forward from the stern, i.e., 40% of LWL, with the thrust line approximately parallel to the undersurface and 1.25 units below it, i.e., 2.85% LWL below it.
  • the corresponding aft profile shape is shown as 71 in FIG. 14 c, for approximately the last 2.0 units of length of the undersurface, shown as 73 , having a length of 2.5-3.5% of LWL which should be inclined upwards at approximately ⁇ 5 degrees, as shown by angle ⁇ .
  • This is qualitatively different and contrary practice to profile shape of high speed planing boats, which recommend opposite downward camber at stern to facilitate planing without excessive angle of attack, and also reduce hump drag before planing; for example, to alleviate nose-up tendency at bottom of FIG. 2 .
  • the center of longitudinal flotation (waterplane area centroid) varies from 23.3 units from stern (33% of LWL) in supercritical regime, to roughly 15 units from stern (21% of LWL) in transplanar regime.
  • An approximate position is shown as numeral 70 in FIG. 14 a.
  • Variations of the hull's geometry in the example above will alter somewhat the parameters and relations of longitudinal trim, stability, and control. They are also dependent on ratio of weight to volume, for example, weight in tons to cube of length in feet/100.
  • the example given is a guide for ratios in the order of 50 to 85.
  • a ship of 30,000 tons and 750 feet LWL has a weight-to-volume ratio of 71.1. In this respect, it is important to distribute the loading of transonic hull to cause a much greater hydrostatic draft at bow than at stern.
  • variable geometry stern profile is of critical and optimum results, for example, with a trailing edge flap at the stern, but used in a qualitatively different critical and opposite way than stern tabs on conventional planing or semi-planing boats.
  • FIG. 14 d shows TH's undersurface with a flat aft profile 75 adjacent stern 77 , with a stern flap 76 mounted smoothly at the corner of surfaces 77 and 75 , with an upward flap angle Sf of about ⁇ 6°, and a stern flap chord of 2.5% LWL.
  • This negative angle is needed to generate and govern the critical small angle 65 in FIG. 14 b in transplanar regime with a stable 40% CG, and in certain cases in subcritical regimes, but not desired in supercritical or hypercritical regimes.
  • FIG. 14 e shows the stern flap of FIG. 14 d installed in the type of stern of FIG. 14 c modified to accept an optimized hull aft profile.
  • aft of hull 78 which curves gently to the rear in sector 79 of 4.2% LOA, thereby reducing stern's draft about 0.18, thereby increasing immersed volume contribution of rear of TH-II, without excessive local stern draft.
  • a stern flap 82 of about 2.1% chord operated from torque tube 86 by a connecting rod between arm 85 and bracket 84 .
  • the flap has an angle of about ⁇ 5° for transplanar flow, and optionally for subcritical flow up to about ⁇ 8°.
  • the flap reverses the effect of downwards curvature 79 to about zero exit angle at stern flap position 88 for supercritical and hypercritical regimes, and has a special brake position 89 which buries the bow of TH and raises its stern for a drag increment from both sources, especially beneficial for braking in hypercritical and transplanar speed regimes.
  • FIG. 15 shows a new regime which has been developed by this writer's R&D on a transonic hull. It is of such a peculiar nature that even its relation to the transonic hydrofield premises and understandings are not entirely explored, although the absence of shoulder, midbody, and quarter curvatures of TH remains critical and most beneficial. But the water-surface conditions appear to defy full understanding, and is therefore identified as the X-regime, encountered in the higher range of speeds, testimony of which are photographs showing the surface conditions specified in FIG. 15 at, around, and to rear of the stern 91 of TH body 90 . The wake has a flat even depression with a smooth left edge 93 and a smooth right edge 97 which project rearwards as water extensions of the flat sides of body 90 .
  • Wake cross-sections at 96 and 95 show a flat surface of wake below the level of undisturbed flat water-surface areas 92 outboard of depression at 97 , and 94 outboard of depression 95 . There is no evidence in the wake of rays projecting to rear of transom 91 , except as borders of the depressed wake zone. For this x-regime, it is noted, TH has a deeper draft forward as outlined with dash-lines in FIG. 15 .
  • FIG. 16 shows trim and control devices for TH of special value for turns of TH in the hypercritical and transplanar modes.
  • On TH 13 there is wide stern 100 having at its lower edge three stern flap segments hinged at collinear axis 107 .
  • the center flap segment 103 acts principally to provide nose-up trim during a turn, and is therefore raised up by angle 102 in respect to a projection of flat lower TH surface 112 .
  • the flaps are shown for right turn.
  • Right flap 101 is raised by angle 104 larger than 102 , to sink right side of hull 113
  • left flap 105 is lowered by angle 106 in opposite direction than angle 104 , to raise the left side of TH 113 .
  • TH banks to the right and the bottom surface of TH experiences, when yawed to the right under action of conventional rudder, a centripetal force component to the right, which generates a curved path to the right, under Newton's second law. (Rudder not shown in FIG. 16 .)
  • FIG. 16 An alternative turning method is shown in FIG. 16 , comprising a retractable lateral flap 108 hinged at an axis 109 inclined in profile view to have a positive angle of attack ⁇ relative to the flow on the sides of TH.
  • the deployed position of flap 108 shown in FIG. 16 causes an added lift on right side of TH 113 , and since the left flap 114 remains retracted, the right side of TH is raised, causing a turn to the left.
  • right flap 108 is retracted by its actuation piston 111 and is nested smoothly in depression 109 on the side of TH.
  • FIG. 16 Another detail of FIG. 16 is the cross-sectional curvature used at the lateral lower corner of the hull.
  • the right side curvature corresponds to a local ellipse sector with major axis vertical and 2:1 ratio used in certain speed regimes of FIG. 14 a to minimize sinking effects of subduction.
  • a different embodiment is shown at left side with a nearly sharp corner 116 , which is best used for x-regime of FIG. 15 .
  • the left lateral flap 114 can be placed at a lower position on the sides of TH 113 , with more powerful effect.
  • stern flaps of FIG. 16 The mode of usage of stern flaps of FIG. 16 is described in tabular form below in which f represents angles relative to the rearward projection of hull's undersurface 112 in degrees. Flap position Left flap Center flap Right flap Subcritical, ⁇ 4 ⁇ 4 ⁇ 4 straight Hypercritical, ⁇ 5 ⁇ 5 ⁇ 5 straight Hypercritical, right +2 ⁇ 7 ⁇ 10 turn
  • the regimes of use of lateral flaps of FIG. 16 are in the supercritical, hypercritical, and transplanar regimes, with a longitudinal length that can be optimized, if desired, for the preferred speed regime, for example, as outlined below.
  • FIG. 17 shows lateral devices which have various applications, as follows:
  • FIG. 17 also shows a vertical fence-like surface 127 , which can be adapted to be retractable bottom flap for minimum drag in rectilinear motion.
  • rudder 126 When rudder 126 is rotated, it will generate a centrifugal force at the stern, say outward of the paper. This will yaw the stern towards the right.
  • a lateral water flow component inwards towards fence 127 is developed which raises the pressure on the right side of fence 127 and therefore rolls TH right side upwards.
  • the combined action of yaw by the rudder and roll by fence 127 causes the generation of a centripetal force on the hull towards the left, causing a left turn path in accordance to Newton's second law.
  • the centripetal force has two parts: one is the inward component on the bottom of the hull, and the other is the inward force on the right side of the hull. Combined they can generate very tight radius of turn.
  • TH's weight-to-drag ratio improves with increasing size for various reasons; one important reason is that viscous drag decreases strongly with Reynolds number as size increase at constant Froude number. For example, if drag coefficient with increasing scale from model to ship decreases 50%, and if, for simplicity, the viscous drag were estimated with the cube of the scale, it would be diminished by 50%, but he wave-making drag and the weight would be calculated with the cube of the scale.
  • Monohulls with vee bottoms and planing boats also have substantial buoyancy reserves and planing type surface reserves from midbody to the bow, for the same purposes.
  • the TH design departs from, and is contrary to, these traditional monohull approaches in respect to shapes and volumes for adverse seas, with several important departing TH design features, exemplified in FIGS. 18 a to 18 g.
  • FIG. 18 a shows planview 130 of TH with a length of 70 units and max beam aft of 16 units.
  • FIG. 18 b shows side view contour 132 above static water 134 ; and submerged profile line 136 .
  • FIGS. 18 c to 18 g show cross-sections of TH. The following unique features are noted:
  • FIGS. 18 The specific shapes of TH successfully tested in adverse seas are shown in FIGS. 18 reviewed above, characterized further in the following:
  • a critical parameter is the resulting volume of buoyancy reserve in the forward region of the hull above calm waterplane 134 which can be displaced as a transient condition, for example, during a transient diving encounter into a large wave, such as wave 131 in FIG. 18 b.
  • This additional volume should be related to the water volume displaced by the weight of the ship in calm water.
  • Successful tests of TH have been made with volume ratios in the order of 13% for the additional volume between 80% station and bow in FIG. 18 b, and on the order of 32% for the additional volume between station 57% and station 80%, with a hull's center of gravity at approximately 40% station.
  • FIG. 19 a shows in side view a TH 150 having a forwardly located engine 152 driving a midbody propeller 154 driven through a conventional shaft, both protected by vertical fin 156 which can also provide good tracking and centripetal forces in a yaw.
  • engine 156 At the rear are a pair of left and right engines, only one of which is shown as engine 156 . It drives a vertical shaft 158 which is submerged in rudder 160 to drive propeller 168 mounted on the rudder, or separate and ahead of the rudder.
  • the power plant system can comprise therefore three engines.
  • Fuel tanks 151 and 153 are also located at extremes of the hull, so that heavy components maximize pitch inertia of the hull.
  • the upper part 161 of hull 150 is similar to that of FIG.
  • FIG. 19 b also shows how to fit right engine 156 and tank 151 on right side of garage with left engine 174 with left tank 176 on left of garage, and stairway 178 out of garage. All of which is uniquely possible by max beam at stern.
  • the envelope of the hull follows a faceted criteria of low radar signature, which I review on the right side of the hull, having flat panels shown in the cross-sectional views 18 c to 18 g, comprising flat panels 138 inclined at about 45° to the waterplane, flat panel 139 inclined at about 90° to the waterplane and top flat panel 140 .
  • flat panels 138 inclined at about 45° to the waterplane flat panel 139 inclined at about 90° to the waterplane and top flat panel 140 .
  • 138 left and 138 right both inclined at 45°, and flat panel 140 , approximately horizontal.
  • From an oblique side view from above on right there are only three significant panels: 138 right, 139 , and 140 .
  • the TH shape is extremely stealthy. From the rear, it's detectability is limited to four dispersing oblique surfaces: 141 and 142 on the right, and corresponding pair on the left, without numerals.
  • TH can be designed for low cost fabrication methods, taking advantage of its unique simplicity of shape, especially with the use of prefabricated composite sheets, marine plywood or sheet metal, which can be used in flat elements, and/or with gentle single curvature panels, to obtain hydrodynamically smooth surfaces.
  • FIGS. 20 a, 20 b, 21 , 22 , 23 , 24 , 25 , 26 and 27 without change (except sequential numerals and minor grammatical corrections).
  • FIG. 20 a shows an isometric bottom view of TH comprising flat rectangular lateral sides 200 and 203 , converging at bow 204 in triangular planform; a flat triangular bottom 205 , with centerline 202 ; and a flat stern region 206 .
  • This shape with a wetted triangular profile, as reviewed earlier, transcends wave-making drag of conventional hulls , but may have excessive wetted area and viscous drag.
  • FIG. 20 b shows TH refined with simple construction methods to reduce viscous drag by introducing additional triangular flat at the undersurfaces of the hull, modified to have a hull with flat trapezoidal sides 221 and 223 converging at bow 224 .
  • the undersurface comprises three triangular flats 229 at left, 225 at middle with centerline 222 , and 227 at right. The triangles terminate in flat stern region 226 .
  • FIG. 21 shows a pure triangle surface development of TH in which its sides and undersurfaces of the hull are defined by triangular flat surface elements 231 , 232 , 233 , 234 , 235 , and 236 converging at bow 237 and terminating at stern region 238 .
  • FIG. 22 shows a shape developed from FIG. 21 , but more refined to further reduce viscous drag.
  • Its undersurface and side surfaces comprise main quasi-triangular surfaces 241 , 243 , 245 and 247 , between some of which there are trapezoidal or triangular fairing strips 242 , 244 and 246 , all of which blend in bow 248 , now extending at an angle 250 to the vertical to reduce the rate of volume engagement per unit of time as function of draft.
  • Surfaces 242 , 243 , 244 , 245 and 246 extend rearwardly towards a flat transom 249 of little depth, shown vertical only for clarity of drawing.
  • the upper deck surface adjacent to the transom is now at an angle 240 to the forward deck surface, defining a rearward sub-triangular termination to side surfaces 241 .
  • elements 242 - 246 , and even 244 could be rectangles of very high aspect ratio, the principal gain being lower cost of fabrication.
  • FIG. 23 shows a variation of TH, in which, when there are practical restrictions to hull length and/or hull beam (such as design rules, or available dock length for docking, or maximum beam for trailering purposes, all of which may impact on water length and/or righting moments for a given displacement). It may be necessary to modify the TH archetype of FIG. 19 . For example, hull shape shown in FIG. 20 meets greater displacement for a given maximum beam with a modified quasi-triangular arrangement for a given maximum beam.
  • the main component of the hull comprises a main triangular body of length 254 extending between bow 251 and the triangle's base station 252 in the manner shown in previous figures. But, in FIG. 23 the hull is now extended aft with an aft body of length 255 , extending between triangle's base station 252 and stern region 253 . Note that although the extension is quasi rectangular in planform at deck level along 255 , the submerged undersurface remains flat with main triangular surface components 256 and 257 , and flat near triangular surface components 258 and 259 , extending to transom 260 .
  • a special feature for TH shown in FIG. 23 is the use of vertical or anhedraled winglets 261 and 262 at the rear and of the hull, to extract energy from the fan-like submerged flow field along surfaces 258 and 259 , thereby increasing the hull's effective beam at transom 260 , without increasing its geometric trailerable beam for the case of vertical winglets. If these winglets are inclined by an ahedral angle as on the left side of FIG. 23 , they can begin to act as rear hydrofoils supporting part of the weight otherwise supported by hull extension 255 , and they can also serve for directional control.
  • FIGS. 20 to 23 the submerged undersurface have been flat or nearly flat, guided by surface elements and hydrodynamic waterplanes having triangular features, with decreasing draft and increasing beam as the water moves towards the rear, setting a favorable gravitational hydrostatic pressure gradient for the flow which remains active in hydrodynamic condition.
  • FIG. 24 shows a further variation of the TH archetype, this time modified in order to meet arbitrary rules such as IACC: minimum girths, and underbody slopes which require bow and stern overhang from the waterline length at centerplane.
  • IACC minimum girths
  • underbody slopes which require bow and stern overhang from the waterline length at centerplane.
  • the stern overhang can be important, as is exemplified in FIG. 24 , developed from 23 .
  • the TH archetype extends on main hull body length 274 , from bow 271 to maximum beam at triangle's base at station 272 , having a center line 276 on its undersurface.
  • Aft hull extension 275 extends from station 272 to 273 , for the centerline on its undersurface has to be inclined by angle 276 for rule overhang purposes, no more than approximately 12°, defining a 200 mm distance 280 at an aft girth station 279 .
  • the stern is Vee-shaped in planform, to permit a suitable girth 282 within IACC rule.
  • FIG. 26 shows my archetype hull in inverted position for clarity, having lower surface triangles 290 r and 290 L, and a modified stern with inverted Vee or diagonal transom sides 293 and 294 , defining an internal a triangular stern exit with a forwardly oriented apex at centerplane. This reduces wetted area without decreasing heeled waterline. Netting 291 supported by tubular member 292 effective “deck” area, but with a decreased hull weight.
  • the hull (canoe) of FIG. 26 is designed to be able to operate under sail, engaging left or right hydrodynamic waterplanes on one or the other half of its undersurfaces, 290 L or 290 R, which decreases wetted area. Planing may be desirable if it increases hydrodynamically the hull's hydrostatic righting moment, or otherwise decreases total drag.
  • FIG. 27 is a unique development of this writer's TH hull with a very deep-v transom cuts 296 and 297 defining a triangular recess for flow exit at the stern.
  • the hull of FIG. 27 should be heeled to one side or the other, establishing engaged hydrodynamic waterplane shapes 297 a when rear end 297 is engaged by the water, and 296 a when side of 196 is engaged.
  • a large weight savings and wetted area reduction results from the deep Vee, with a large effective “deck” area retained by bar 298 and netting 298 a.
  • FIG. 27 also shows special appendages for TH hull under sail, comprising a rotating fin keel 299 which can be moved along arc 299 c, and right and left rudders 299 b and 299 a, either of which is engaged when sailing upwind; for example, 299 b when side 197 is engaged according to waterplane 297 a.
  • the trailing edge of both fin 299 and rudder 299 b should be rotated to the right in the figure, or clockwise.
  • Rotating fin keel 299 could be substituted by a non-rotating narrow fin and a large rotating flap. Foil rotation permits operating the TH hull at a trans-leeway angle shown in FIG.
  • FIG. 28A shows a multihull using two parallel TH hulls 301 and 303 which at supercritical speeds and above have no wake interference in the vicinity of the vessel, as can be seen by inboard ray patterns 309 and 311 . Outboard rays are 313 and 315 . The hulls are driven by propellers 305 and 307 . Hence, the hydrodynamic TH benefits are retained in full.
  • FIG. 28B shows a radically different multihull approach exemplified with TH hulls, but applicable to other hulls.
  • right and left hulls 310 and 312 have their longitudinal axis of symmetry outwardly oriented in a toe out angle in respect to a general axis of symmetry.
  • outboard rays 320 and 322 have diminished size and drag effect, with less wetted side surface, but inboard rays 324 and 326 tend to interfere tending to raise water level and drag, and increase inboard wetted surfaces. This may be recovered by favorable interference at the rear end of hulls 310 and 312 .
  • water accelerating propulsive means 330 shown as a battery of five water jets between the hulls which when operational recover certain energy content of rays 324 and 326 , reducing their tendency to increase water level, reducing their drag contribution, reducing inboard lateral wetted surfaces, and increasing efficiency of thrust generation in that in addition no boundary layer from hulls falls into the powerplant.
  • the clean accelerative flow appears as 332 .
  • FIG. 28C is a trimaran with three TH hulls 340 , 342 , and 344 , but also could be conventional hulls with no toe out, since for either case, the two propulsion batteries 346 and 348 , each of the type in FIG. 28B , which provide unique interactive benefits of decreasing drag and increasing thrust.
  • the power groups can be made with batteries of outboard marine engines.
  • FIGS. 28 A For a given overall length and weight, the catamaran configuration offers unique benefits to TH, in that the beam loading, for a given hull length and entry angle, is halved, facilitating the more rapid transition from supercritical to transplannar hydrodynamic regimes on both hulls.
  • toe out angle need not be restricted to hulls having longitudinal axis of symmetry, and an asymmetric planform can replace the angle of tow out, or diminish it, it being understood that the asymmetric shape of the hull would be symmetric in respect to a central longitudinal line.
  • the word “batteries” is used to indicate a single flow propulsor, or multiple flow propulsion, mounted between the hulls of multihulls of the referred figures, for example, the five water jets of group 332 in FIG. 28B , or the pair of two water jets 346 and 348 in FIG. 28C .
  • Important hydrodynamic characteristics of FIG. 29 are as follows: minimal interference drag, for example, between non colliding principal rays 363 and 364 good alignment of hydrostatic centers of buoyancy of the three hulls for good hydrostatic lateral stability lower length/beam ratio of outer hulls, compared to center hull, to decrease beam loading and therefore the induced drag of outer hulls.
  • Curve (a) shows the drag growth between speed/length ratios of 4.27 and 7.15, which is large at constant beam loading, but when beam loading is decreased by increasing beam relative to length, and/or by decreasing weight, as in curve (b), drag is reduced.
  • a different and less favorable situation is shown on the left side of trimaran of FIG. 31 , having a slender central displacement hull 371 with a high length/beam ratio to facilitate wave piercing, and a left lateral hull 373 also of slender type, with a similar length beam ratio.
  • Their first problem is a high friction drag which increases with square of speed, as shown in qualitative curve (c) of FIG. 30 .
  • drag When operating at a speed/length ratio of up to about 3, drag is not excessive, and decreasing weight has small benefits as shown in curve (d).
  • friction drag level becomes unacceptable in both curves (c) and (d).
  • wave making drag becomes significant, due to shoulder curvature in the planform of conventional hulls.
  • the shorter length of hull 373 has an inherent problem.
  • a conventional planning hull such as 375 shown in dash lines in FIG. 31 , could have less drag in the planning condition at 56 knots, compared to conventional displacement hull 373 at the same speed, for example as shown in curve (e) in FIG. 30 , but only in flat water.
  • planning hull 375 would have unacceptable drag due to wave encounter, and high structural load as well rendering it impractical.
  • a more favorable situation applies for a trimaran hull using a slender central displacement hull such as 371 in FIG. 31 at speed/length ratio of 3 but with outboard hulls of transonic hull shape such as 377 in FIG. 31 of same or similar length as 373 , but with a wider beam.
  • Hull 377 could operate at high speed/length ratio of about 5, but its drag on curve (a) or (b) in FIG. 30 would be much lower than the conventional outboard displacement hull, as curves (c) and (d) shown in FIG. 30 for the speed/length ratio of 5.
  • FIG. 30 are qualitative in nature, as their precise value for central and outboard hulls would depend on relative weights, beam loadings, length/weight ratios, and similar characteristics which are dependent on specific design choices.
  • FIG. 30 are useful guides for a person familiar with multihull design theory and practice, to guide specific design choices.
  • wing 380 is hinged at its root hinge 381 to permit angular motion 383 while its outboard hull 381 accepts lateral ocean wave 382 with minimal slam loads and drag growth due to wave encounter.
  • Hull 381 could be of slender displacement type, or alternatively, conventional planning, or TH type.
  • Wing 380 is mounted on center hull 379 , which could be of any of the above hull types, at hinge 381 . Its angular excursion could be powered by the lateral wave, and/or by hydraulic piston 383 , or a combination of power and damping by a hydraulic piston system similar to 383 .
  • FIGS. 28 A to 32 described TH multihull applications to large craft, but also representative of medium size craft such as passenger boat, ferries, and military patrol and coast guard boats, by scaling down as appropriate.
  • TH multihulls are not size dependent, and can also be applied to small boats and man powered craft with or without auxiliary or emergency power devices. This is exemplified in a kayak type craft specified first as a monohull, with additions of lateral hulls thereafter.
  • FIG. 33 shows a monohull manpowered kayak type hull 390 with flat sides and faceted top surfaces for ease of manufacture, and/or assembly in the case of a kayak kit.
  • Open cockpit is shown as 391 and stern at 392 .
  • manpowered speed may barely reach supercritical range
  • the TH configuration as kayak offers three important benefits: one is the feasibility for a person to climb aboard in deep waters from the stern end, without rolling the hull, improving in this unique way safety in an emergency deep-water condition.
  • Another is the ability of an arm to execute paddle motion from a narrow cabin, enabling the arm to remain close to the body, while retaining a broader beam for lateral stability aft of the cabin. This is directly contrary to usual kayak design, in which a maximum beam is at the cockpit.
  • the third advantage is smoother ride with less drag growth due to encounter with a choppy sea surface, due to the very sharp entry angle of the hull.
  • FIG. 33 can be generally vertical. Alternatively, they can be inclined outwardly, for example, by changing the bow angle to 393 , similar to 395 . This slides the deck's planform 394 forward relative to planform of bottom surface, signified as 396 , thereby slanting the flat right side 397 , and the opposite side outwardly, as shown in FIG. 34 .
  • FIG. 35 shows hinged lateral bodies to enhance lateral stability when deployed, by way of example, on a TH hull, but applicable to all types of kayaks and similar craft.
  • FIG. 35 shows retracted right body 400 hinged at axis 401 substantially above waterplane 402 , so that the body 400 does not interfere with water surface 403 when the craft is in motion.
  • lateral stability needs to be increased, for example at slow speeds, or stationary, or in adverse seas, it is deployed to position 400 ′, with its lower surface when deployed adjacent the water's level 402 .
  • FIG. 36 shows an isometric view of the body of FIG. 33 with lateral stability bodies of FIG. 36 in the 400 retracted condition.
  • FIG. 37 shows the same craft with the stability bodies in the deployed 400 ′ condition.
  • Lateral stability can be improved for a TH kayak, or any type of kayaks, by means of an asymmetric auxiliary hull, or “proa” configuration, such as shown in FIG. 38 with main hull 405 , and a lateral or auxiliary hull 406 , supported by wing 407 .
  • Body 405 should be small so as not to generate drag and weight.
  • 406 there is special benefit for 406 to be of TH type, because at or near critical speed of main hull 405 , auxiliary hull 406 is evidently operating in transplannar regimes, due to its short length.
  • TH offers a separate gain, compared to conventional slender displacement shape used for a lateral hull.
  • the TH shape of auxiliary body 46 is specified in FIG. 39 .
  • FIG. 39 shows the top view of main TH hull 405 , side wing 407 and lateral body 406 , with the corresponding side view in FIG. 40 .
  • Coordinates and dimensions are in inches for a manpowered craft, but could be feet for a small ferry or military craft, and meters for a larger craft, with different top surfaces.
  • the coordinates and sections of lateral TH body 406 are shown in FIG. 41 .
  • the X (longitudinal) and Y (lateral) coordinates can be increased for a lateral body of greater buoyancy, for example, with a factor up to about 1.6 and the X coordinates for a more slender body, for example, with a factor of up to 2.0, approximately, without change in principal TH hull.
  • the asymmetric shape is designed to reduce tendency of adverse roll on a lateral sea.
  • FIG. 42 shows a TH trimaran with auxiliary or emergency propeller, the inventive aspect of which is described below:
  • Air propellers have been restricted to special fields, for example boats for use in swamps and shallow waters, usually with hulls having rectangular planforms and large beams, with length to beam ratios of approximately four.
  • Air propellers have also been used on ground effect machines, also of similar rectangular planforms, capable of operating over the water or land, such as Hovercraft.
  • air propellers have been proposed and used for propulsion of hulls of seaplanes, which are slender but have wing aerodynamic lift at high speeds.
  • manned powered watercraft such as rowing shells, kayaks, and similar boats have used oars, paddles, and even the interesting moving fins as used in the very efficient propulsion unit of Hobie Mirage kayaks. All these boats are slender.
  • Kayaks and similar boats have also considered the use of marine propellers powered by leg motion, as shown in the internet under various names, and even the use of electric driven marine propellers as auxiliary power plants, or as emergency power plant, or as alternative power plant, requiring batteries to drive the electric motors which drive marine propellers.
  • One serious impediment is encountered when beaching such manpowered craft with marine propellers protruding below the surface of the water, normally requiring that they be retractable, which adds complexity and cost to such craft. They also add drag when motion is restricted to oars or paddles, and batteries of standard type, though low in cost are very heavy, and can reach the weight of an entire single place kayak.
  • air propellers to provide auxiliary driving thrust with battery power of slender craft is unprecedented, until the present invention.
  • the present invention pertains to the use of aerodynamic propellers, or ducted propellers, or fans, hereafter referred to as aerodynamic impellers, in an unprecedented and unique application for slender manpowered vessels, as alternative, auxiliary, or emergency powerplants, using batteries which can be charged on shore, or charged/recharged with solar panels on the surface of the manpowered craft.
  • FIGS. 42 and 43 Special slender TH boat configuration which provides new unique features are specified in FIGS. 42 and 43 .
  • the principal features of FIG. 42 are as follows: Principal TH hull 409 support lateral wings 411 and 410 , which in turn support outboard TH hulls 413 and 412 .
  • Rear deck 414 supports electric motor 420 which drives air propeller 415 using battery 421 .
  • the large upper surface area of the TH trimaran should be used for solar panels in the figured shaded area 416 (top of forward deck), 417 (top of wings), and 418 (top of rear deck), to charge batteries when on route on top of a car or on a trailer, when stationary on a beach, or when rowing.
  • the inclined panels 416 and 418 have a shallow angle, up to 45°, to optimize capture of solar energy early morning or late afternoon.
  • the wings can be folded upwards for transportation about hinge 419 , or downwards relative to hull 409 , to catch afternoon rays of the sun, for example by tilting hull 409 on the beach, or by heeling the hull in the water.
  • Air propeller 415 could create problems for persons not used to propeller driven vehicles, it is preferred, and recommended by this writer, that aerodynamic propulsion should use a shroud or duct.
  • Small light electric motor 420 is powered by batteries 421 mounted at a low position inside the hull, thus avoiding need to have a transmission.
  • a brushless motor is preferred for greater efficiency and cool running temperature.
  • Light weight batteries such as nickel-metal hydride, or even better, expensive ion-lithium batteries, would minimize vehicle weight. High efficiency of battery and electric motor will be key for light weight needed in a man powered craft, because it needs to be carried, often by hand from shore to a car. Added cost provides added safety, and with the propeller as in FIG. 42 , there is no obstacle to beaching the TH trimaran.
  • a safe alternative is the use of a ducted propeller shown in FIG. 43 , comprising duct 423 mounted on rear deck of hull 409 , with an internal impeller 425 and a frontal louver or mesh 426 , to impede accidental insertion of a hand, or air-driven rags.
  • a similar mesh should be used on the ducts rear mouth, which can also have an air rudder 428 .
  • the external upper and side surfaces of the duct can also have solar panels symbolized as 429 , further increasing solar panel area.
  • FIG. 44 The folding feature of the wings supporting the lateral hulls is shown, by way of example, in FIG. 44 , for the “proa” of FIG. 38 , with hand retracted position over and across the hull, and hand driven deployment path 430 for deployed position of FIG. 38 .
  • FIG. 45 shows half of the retracted position for the trimaran of FIGS. 42 and 43 , with deployment path 431 .
  • Similar retracting and deployment methods can use electric or hydraulic acceleration, specially for larger craft.
  • FIG. 46 shows a new type of stern planform for TH configuration using a vee exit.
  • the flow below the hull now has different subcritical pattern shown in FIG. 47 , comprising two separate semi-gothic arch wake planforms 432 and 433 which occur at different Froude numbers than for a rectilinear stern planform, as has been established experimentally.
  • the subcritical flow becomes a single supercritical wake between rays 434 and 435 at a different Froude number, compared to that for a supercritical regime of a non-vee TH stern planform.

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CNA2005800108937A CN101052561A (zh) 2004-02-09 2005-01-15 跨声速船体和流体场
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CN101052561A (zh) 2007-10-10
EP1718518A1 (fr) 2006-11-08
AU2005212216A1 (en) 2005-08-25
WO2005077745A1 (fr) 2005-08-25
EP1718518A4 (fr) 2011-05-11
EP1718518B1 (fr) 2016-09-14

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