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Old 04-02-2021, 11:09 AM   #11 (permalink)
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Kachi22i's extra views.

Wow! Thanks!
So there is some body camber in plan-view. Pressure recovery. That's what I was curious about. Smart design.

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Old 04-02-2021, 11:34 AM   #12 (permalink)
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The cross section diagrams of this new craft are different than most other WIG's, SES's and hydroplanes which usually feature an underbelly straight line (or positive camber airfoil) from bow to stern that tapers downward at the stern, and is higher in the front.

This design uses a negative camber airfoil to presumably pocket more air, that is the main difference from prior efforts from what I can tell.


Camber
https://www.skybrary.aero/index.php/Camber

Quote:
Production of lift is dependant primarily on airspeed, angle of attack and aerofoil design. A fundamental component of aerofoil design is the camber which will vary with the intended speed and purpose of the aerofoil. The upper surface of the aerofoil will always have a positive camber while the lower surface may have a positive (convex), zero (flat) or negative (concave) camber as appropriate for the intended use. An aerofoil in which the camber of the upper and lower surfaces are the same is referred to as symmetrical and is most often found in aerobatic aircraft intended for inverted flight. A supercritical aerofoil will usually incorporate a negatively cambered lower surface. Designers may also vary the camber over the span of the wing to improve stall and stall recovery characteristics.
I'd describe this craft as a fanless and skirtless ram-air SES using lifting body aerodynamics.

A real mouthful.

Surface effect ship
https://en.wikipedia.org/wiki/Surface_effect_ship
Quote:
A Surface Effect Ship (SES) or Sidewall Hovercraft is a watercraft that has both an air cushion, like a hovercraft, and twin hulls, like a catamaran. When the air cushion is in use, a small portion of the twin hulls remains in the water. When the air cushion is turned off ("off-cushion" or "hull borne"), the full weight of the vessel is supported by the buoyancy of the twin hulls.

The SES has two advantages over a hovercraft for open sea operation: it is more resistant to slipping sideways when acted on by air or sea, and it can use water jets for propulsion since the inlet nozzles are always covered by water.
Lifting body
https://en.wikipedia.org/wiki/Lifting_body
Quote:
A lifting body is a fixed-wing aircraft or spacecraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing. Whereas a flying wing seeks to maximize cruise efficiency at subsonic speeds by eliminating non-lifting surfaces, lifting bodies generally minimize the drag and structure of a wing for subsonic, supersonic and hypersonic flight, or spacecraft re-entry. All of these flight regimes pose challenges for proper flight safety.
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Old 04-02-2021, 12:28 PM   #13 (permalink)
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SES lifting body

I'm intentionally avoiding a deep-dive into the subject, so I apologize in advance.
The America's Cup racers were using a form of hydroplane/keel stabilizing foils a decade or so ago.
The hull would rise out of the ocean onto the foils to reduce wetted area, while stabilizing the boat against capsizing. It was very clever.
This new boat, I'm guessing, was designed for a target velocity, at which it would also rise, to reduce friction losses, while maintaining enough hull in the water for directional stability?
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Old 04-02-2021, 01:08 PM   #14 (permalink)
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Quote:
I'd describe this craft as a fanless and skirtless ram-air SES using lifting body aerodynamics.
Two conjoined flying boats?

What do you make of the fences under the leading edge?
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Old 04-02-2021, 01:24 PM   #15 (permalink)
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fences

Quote:
Originally Posted by freebeard View Post
Two conjoined flying boats?

What do you make of the fences under the leading edge?
I've only observed where they are placed to mitigate span-wise flow. If it's a 'laminar' foil, then that's exactly what they'd be after, as NACA ( NASA ) has published long ago that a span-wise flow would immediately trigger the 'jump' to turbulent boundary layer and higher drag.
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Old 04-03-2021, 05:22 AM   #16 (permalink)
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Quote:
Originally Posted by freebeard View Post
Two conjoined flying boats?

What do you make of the fences under the leading edge?
I think Aerohead nailed it.

Perhaps the reason we have not seen these strake/fences on catamarans, trimarans and tunnel hull hydroplanes (be they sail or powered) is the speed they are intended to operate at and also the pressurization and compression of air under the craft squeezes the air to the surfaces (I'm making this last part up but will attempt to support later).

I have seen a side to side negative camber between the floats/sponsons/pontoons before where the bottom of the bridging element arcs up to prevent being splashed by larger waves presumably. See Concave Tie-Up below in diagram.


https://www.pinterest.com/pin/275845545915827585/


The above diagram is to illustrate a side to side concaveness, and recall the original craft (Advanced Aerodynamic Vessels, SAS) has a longitudinal concaveness.

Advanced Aerodynamic Vessels, SAS
https://www.aavessels.com/
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Old 04-03-2021, 05:56 AM   #17 (permalink)
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Here is an example of what I believe is Renaissance Prowler's development of that space in-between.

Nothing:
https://www.renaissanceprowler.com/prowler-36



A Something Bump
https://www.renaissanceprowler.com/prowler-31



Strake/Fence/Chime Madness

https://www.renaissanceprowler.com/why


I'm guessing the thin fences on the more aircraft-like (Advanced Aerodynamic Vessels, SAS) would be frowned upon by boaters that might be looking at the Renaissance Prowler.

Factors such as durability of taking waves and acting as a hazard to swimmers/divers plus that fences just might not look "boat-like" enough could be factors.

And finally, fabrication of a boat hull is different than an aircraft like skin.

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