So the amphibious seaplane thing is pretty much dead in the water so to speak ??

Discussion in 'Bush / Float flying' started by crushed nuts, Sep 8, 2018.

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  1. Sep 8, 2018 #1

    crushed nuts

    crushed nuts

    crushed nuts

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    Spent a few hours reading old posts and trying to glean information and ideas but came to the conclusion theres nothing new !!skis ,and cats and the guy that got banned and the tunnel ideas !. AFTER some long thinking and sketching I can see merits in that concept but would like to pursue it further before moving on !
    I was able to spend some time walking around and poking into an old seaplane awhile back and able to study what and how and also the inside of the hull and construction etc will have to search for the photos I took !
    The step for a small hulled craft wouldn't be necessary and as was mentioned a hull with rocker could achieve the same effect that's for real !:)!
     
  2. Sep 8, 2018 #2

    Doggzilla

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    Not sure what people have against amphibs, but they can actually be very competitive.

    The Lake series of amphibs is actually slightly better than most Cessnas and Pipers with the same engines. WITHOUT FLOATS.

    They are significantly better than any float conversion.

    A twin engine lake would be like a baby Catalina, and would vastly increase control on the water by allowing variable throttle control.

    An enlarged Lake with twin 200hp diesels would carry as much as a beaver, but 30% faster and probably 35% reduction in fuel.

    Not to mention being able to use vastly less expensive fuel.

    There would be a significant motivation for commercial operators to upgrade.
     
  3. Sep 8, 2018 #3

    Riggerrob

    Riggerrob

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    A step is needed to break the suction created by the curved forward hull
    NACA, EDO, Aerocet, have tested a wide variety of steps over the years.

    I wonder if exhausting air (17 degrees aft of the centre of gravity) would serve the same function as a step.

    There is a Supplementary Type Certificate for adding step vents to Republic RC-3 Seabees. Unfortunately I have not seen any pilot reports on the STC.
     
  4. Sep 8, 2018 #4

    Himat

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    Other seaplane hull design than a stepped hull has been tested and made to work. Hydrofoil, hydroski and air cushion do come to mind. Trike flying boats have planning hulls with no step and work just fine.

    I would rather say that a stepped hull is a proven way to design a well performing seaplane hull. Done right the only difference between a stepped seaplane hull and an ordinary fuselage is the extra weight to withstand higher loads and slightly more aerodynamic drag.

    Exhausting air behind a faired step have been tried. Did work if I remember right from the NACA report, but no real advantage as the blowing system add considerable weight and take up space in the hull.
     
  5. Sep 8, 2018 #5

    Topaz

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    Hmmm. Deja vu...
     
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  6. Sep 9, 2018 #6

    CharlieN

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    Have you ever seen a displacement hull when it approaches it's hull speed?
    Do you understand what and why the step in in the hull?

    On the first point, the rounded hull shape is a displacement hull. As it gains speed the hull develops a strong downward lift, a suction if you will. Watch any sailboat as it gains speed, the bow gets sucked down which greatly builds drag till it reaches what is called "hull speed" Canoes and Kayaks are greatly affected by these forces.
    Ocean going vessels, be these freighters, tankers or whatever have added the bulb on the bow which to the non understanding would seem to create drag. But what that bulb does is greatly reduce the downforce which limits the hull speed.

    The step,
    If you take a conventional V hull, this being a planing hull, the center of lift is a balance of both aerodynamic and hydrodynamic lift. The center of lift depending on details is very far aft. Too far aft for the use under an aircraft due to the power to get a relatively nose heavy body up out of the water. Consider the common "Bowrider" you see on the water,load the bow area and some of them might not get on "plane"
    This is where the step comes in, it allows for moving the center of lift forward so you can get the aircraft to balance when climbing up onto plane as well as a balanced and controlled planing over the water.

    The use of deices such as hydrofoils allow for small high energy lift that can allow more freedom as to the contour of the rest of the hull.
    The blown hulls are intended to break the suction of the water to allow the hull to climb onto plane easier.
    This is a very shortened description such that it is far from inclusive of all variations and details.
     
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  7. Sep 9, 2018 #7

    crushed nuts

    crushed nuts

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    Why and how did displacement hulls and canoes even get mentioned , and tankers and ocean going ships of all things ???to much nonsense information and comparing and clouding the issue at hand before we even get started . So shelve all this issues and stuff

    Yes I know all about the effects of hull shapes and suction etc etc and yes a canoe or a displacement hull can be made to plane just by adding a few things and chopping the back off the canoe !! have been designing high speed water craft all sizes for more years than I wish to remember !
    And never had any use or call for STEPS of any sort or shape or size !
    YES i understand about rotation at take off and landing !!, the use of rocker and its placement and shape could be made and located to get over this phenomenon and not get suction !
    On a amphibian type hull used on small planes designed properly (NO STEP required )could position the hull at the correct attitude and hold it there for take off without even touching the controls only the throttle I have followed this that's done on other small 2 seater amphibious planes
    ROCKER shape and placement on any hull can be made to work like magic and for high speed hulls and can be completely user friendly !
     
    Last edited: Sep 9, 2018
  8. Sep 9, 2018 #8

    CharlieN

    CharlieN

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    You spoke of a rockered hull with no other information. With no other information the rocker hull is taken as a curved bottom which 95% are displacement hulls.
     
  9. Sep 9, 2018 #9

    cluttonfred

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    I would love to see a completely conventional all-metal amphibian along the lines of the Thurston Teal but more the size and weight of a light Volmer Sportsman to put it squarely in the LSA category (650 kilograms (1,430 lb) gross weight, stall speed of 45 knots or less). The Sportsman itself is already close enough that a careful build with a Rotax 912 would be LSA legal. That would totally negate the ridiculous arguments from ICON and others that they can't possibly build a safe amphibian without waivers of the normal rules.

    C-FYSJ-12-740.jpg nineteenA.10381157.jpg

    VOLMER VJ-22 SPORTSMAN
    Specifications (85 hp engine)
    Data from Jane's All The World's Aircraft 1993-94

    General characteristics
    Crew: 2
    Length: 24 ft 0 in (7.32 m)
    Wingspan: 36 ft 6 in (11.13 m)
    Height: 8 ft 0 in (2.44 m)
    Wing area: 175.0 sq ft (16.26 m2)
    Empty weight: 1,000 lb (454 kg)
    Max takeoff weight: 1,500 lb (680 kg)
    Fuel capacity: 20 US Gallons (76 L)
    Powerplant: 1 × Continental C85 air-cooled flat-four, 90 hp (67 kW)

    Performance
    Maximum speed: 95 mph (153 km/h; 83 kn)
    Cruise speed: 85 mph (137 km/h; 74 kn)
    Stall speed: 45 mph (72 km/h; 39 kn)
    Range: 300 mi (261 nmi; 483 km) (max fuel, no reserves)
    Service ceiling: 13,000 ft (4,000 m)
    Rate of climb: 600 ft/min (3.0 m/s)
     
  10. Sep 9, 2018 #10

    crushed nuts

    crushed nuts

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    time to get out and about more !!things are constantly changing !

    Rocker and its advantages and what can be done with it is very sadly misunderstood even by seasoned professional boat builders !
    Like everyone you possibly have the idea its just a curved keel and that's it !! Sorry there's way more to it than just a simple curve !
    Like I said before hull shapes and manipulating things is a whole thing all on it own ! Power boat races builders and drivers have been doing it since the 1920/30 and beyond I never got into it till I worked for a very clever fast power boat designer and we sat and he described to me in fine detail what was needed on the new plugs we were making for a range of tunnel hulled fast family boats !
    The cleverness of rocker !!its shape !!Its location and size I have used ever since and the advantages can be mind blowing !
    ONE thing THAT IMMEDIATLY SPRINGS TO MIND is cornering !!
    Being able to spin a hull at speed within its own length at 40 mph ! All done by using rocker BUT THE point of the rocker and where its located is the secret !In this case the boat never lost or dropped speed either ! !But rocker can be used to help directional control in rough water and it was unbeatable ! food for thought
     
  11. Sep 9, 2018 #11

    TFF

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    The biggest problem with seaplanes has nothing to do with flying. Docking is the biggest problem. It's like operating a blimp in the wind from a control standpoint once you have slowed down and are shut down. It's where aircraft get damaged. In the end it limits where you can go. Essentially thrusters would be the best thing to work on.
     
  12. Sep 9, 2018 #12

    Riggerrob

    Riggerrob

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    ———————————————————————————————

    Thrusters .... er ...... electric trolling motors are probably the most precise way to dock a seaplane, however, I wonder if they are light enough to stay within LSA weight limits.

    Seabee - and several others - use reverseable propellers to help with docking.
    Spinning propellers are also hazardous when securing lines. Seabees or pylon-mounted pushers seem to present the lowest risk to dock hands.

    Another issue is avoiding bashing wings into docks. Floatplanes solve that problem by mounting wings way too high so that they hang over floating docks.

    My latest sketches - of small flying boats - include parasol wings and Dornier-style sponsons/seawings.
     
  13. Sep 9, 2018 #13

    BJC

    BJC

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    Are you “tunnels” reincarnated?


    BJC
     
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  14. Sep 9, 2018 #14

    Topaz

    Topaz

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    Hmmm. Deja vu.
     
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  15. Sep 9, 2018 #15

    FritzW

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    He used "the guy that got banned", "tunnel" and double exclamation points in the first sentence of post #1.

    In Police work we had a term for that sort of thing :roll:
     
  16. Sep 9, 2018 #16

    crushed nuts

    crushed nuts

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    No not tunnels but I wish I had seen and been here when he was FIRED up and in action ! he was a few steps ahead of a lot of stuff I read before testing the waters here !
    Where did he come from ?
     
  17. Sep 10, 2018 #17

    FritzW

    FritzW

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    Tunnels.jpg
     
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  18. Sep 10, 2018 #18

    BJC

    BJC

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    You certainly seem to share tunnel’s rampant use of exclamation points.


    BJC
     
  19. Sep 10, 2018 #19

    spaschke

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    I wouldn't say dead in the water, but it seems only LSA flying boats are in the works. High power experimental amphibs like the sea cat, shark, seawind and adventurer don't seem to sell. They fit my mission, which is why I am building one.
    I think the Chaika L-4 derivitives (Aerovolga) are still in production (Sea Bear) if you want a light twin amphib. They provide a better way to dock. And obtainable in the US now. I wish they were available here 5 years ago.
     
  20. Sep 10, 2018 #20

    cluttonfred

    cluttonfred

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    In addition to pylon-mounted engine configuration like the Thurston Teal and other designs, the parasol wing with a wing-mounted engine and sponsons like the Dornier Libellule (or auxiliary floats like the bigger Shavrov Sh-2) is also very appealing in a small flying boat or amphibian. I think that latter configuration works better for a very light amphibian in terms of weight and balance issues because it puts the heavy engine forward and the pilot and passenger very close to the center of gravity.

    libelle-1-big.jpg shavrov-2.jpg

    As a matter of fact, other than having a limited payload because of the rather heavy empty weight, the Dornier Libelle I was pretty much spot on as an LSA for water operations...back in 1921! With a modern engine producing more power with less weight and modern understanding of how to build light but strong all-metal structures, it would be just great. Bring back the Libelle! ;-)

    DORNIER LIBELLE
    Specifications (Libelle I)

    General characteristics
    Crew: one
    Capacity: two passengers
    Length: 7.18 m (23 ft 7 in)
    Wingspan: 8.5 m (27 ft 11 in)
    Height: 2.27 m (7 ft 5 in)
    Wing area: 14 m2 (150 sq ft)
    Empty weight: 420 kg (926 lb)
    Gross weight: 640 kg (1,411 lb)
    Fuel capacity: fuel 42 kg (93 lb)fuel + oil 10 kg (22 lb)
    Powerplant: 1 × Siemens-Halske Sh 4 5-cyl. air-cooled radial piston engine, 45 kW (60 hp)

    Performance
    Maximum speed: 120 km/h (75 mph; 65 kn)
    Cruise speed: 100 km/h (62 mph; 54 kn)
    Range: 300 km (186 mi; 162 nmi)
    Service ceiling: 1,600 m (5,200 ft)
     
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