Experimental sea plane please follow along

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by michael Hille, Jan 26, 2020.

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  1. Jan 28, 2020 #21

    michael Hille

    michael Hille

    michael Hille

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    I see what you mean , the problem I have is I have already designed the wing strut braced not cantilever. I just haven’t drawn in the struts. But yes agree it would be more efficient
     
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  2. Jan 28, 2020 #22

    dog

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    The build concept is the first tig welded aluminum hull amphibious aircraft ( that I know of ) .I believe I can make it lighter than fibreglass . Plan is to build a very low cost aircraft the is simple to build lightweight and be able to land anywhere so it will have big turf glide tyres . The hull design should allow for very rough water for an amphibian.

    You are hitting all of the main wants I have in an amphib.Top of the list bieng what "sea state" will
    it land(alight) and take off in.Pictures of the do-24
    in sea trials setting the far end of what can be done.
    I see your mdf mock up has seroius strakes like a mini bombardie water bomber hull, sea bee pusher prop and kinda dornierish sponsons, letting the landing gear stick out isnt going to slow down a 100 knot 2 place plane with 160 hp,tig welded hull,its about time.
    AND thank you for posting a description and pictures, as I have lower bandwidth rural internet.
    There is another thread focusing on safety,with a number of posts on pusher motors entering the cabin in otherwise surviable incedents,and how
    some planes were designed from the start to direct
    the energy of the motor / prop somewhere other than the backs of the occupents heads in an incident.Whats your thinking around that?
    Is the whole fuselage/hull going to be one piece?
    If you covered all that,just jot it down to my enthusiasim for the entire subject of anphibs.
     
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  3. Jan 28, 2020 #23

    JohnB

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    It will be able to be registered as a 2 or 4 seat if 2 seat it will have a massive baggage area for camping fishing Diving ect. I will be using full span flaparons like my Cruzer. Big matco brakes for great stopping ability for short field landing and takeoff - my Cruzer takes off in lees than 50m loaded and lands in less than 80m hard on the brakes and a climb rate of 1500ft/m with this power so I’m expecting great performance using this modified wing type minus some losses due to a pusher configuration and maybe additional drag so should be a fun project . If all goes to plan happy for any imput or ideas as I don’t pretend to know everything and I’m always learning.[/QUOTE]



    Be careful of using a wing that gets a lot of it's lift at high AOA. you can find yourself trying to rotate to an angle that puts the tail underwater. Hulled aircraft land and takeoff the water at much shallower angles than land planes, you need an airfoil that matches. I assume you have a copy of NACA Tech Note 2302 which defines what works and more importantly what does not as far as small seaplane design goes. Hull width to length,deadrise angle, tail volume, tail to keel angle and another hundred gotchas waiting for the unsuspecting seaplane designer.
    Just trying to shorten your learning curve, Ken Rand tried to convert his KR2 to amphib, disaster. With a pusher engine directly behind the cabin it is exceedingly difficult to keep the air flow around the cabin attached . As a result you get nasty flow into the prop. Look up Glass Goose and all the bandaids they tried to make it work. The Wider the cabin the harder it is to achieve. The Seabee makes it work (barely) but you can't use flaps on takeoff as it robs too much air from the prop.
    You have bitten off a BIG project, good luck with it. JohnB
     
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  4. Jan 28, 2020 #24

    Riggerrob

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    May I make a couple of suggestions about wheels?
    First off: good start on your nose wheel. If you steal a nosewheel off a Wipline or Aerocet (lighter) amphib float, you can save yourself a few hundred hours on design and fabrication. Both those floats use spring steel or springy fibreglass to absorb landing impacts. They also both retract closer to the nose cone. The thing is that they keep all the retract mechanism above the waterline … simplifying construction and reducing the amount of stagnant water even held briefly in wheel wells.
    Have you ever noticed how big the air vents are in Grumman Mallard main wheel wells?

    Similarly, if you leave the main wheels half-exposed out the sides of the sponsons, you can use them as dock bumpers … though you might need to stiffen the sponson structure near the axle. Rubber blocks?
    The next question is whether main wheels will rub more vertically or horizontally relative to the dock?

    If you retract main wheel struts just aft of the step, you don't need doors.
    If you look at the underside of the Dornier S-Ray (ultralight flying boat) you will notice that the step continues across the entire span of the sponsons.
     
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  5. Jan 28, 2020 #25

    Riggerrob

    Riggerrob

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    With some clever fore-thought, you could integrate wing struts with a wing-fold mechanism allowing you to trailer your seaplane to the lake.
    Hit: look at the Stits Playmate wing-fold mechanism.
     
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  6. Jan 28, 2020 #26

    Riggerrob

    Riggerrob

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    Wing struts can be built lighter than cantilever wings. At only 100 knot cruise, struts do not contribute much more drag.
    While bolting outer wing panels to sponson tips may sound more efficient, it will be more difficult to dock. Most flying boats have high wings to clear docks.

    While you are designing wing mounts, also consider the strength of your engine mount. A long time ago, the US Navy concluded that 40 Gs was about the maximum a human could survive while strapped into an intact cockpit. As long as your engine mount exceeds 40 Gs forward, there is little risk of it entering the cabin.
     
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  7. Jan 29, 2020 #27

    michael Hille

    michael Hille

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    That is some great advice I hadn’t even thought of the engine finding it’s way into the cabin. I will re analyse the strength and stress factors. Thanks for the input
     
  8. Jan 29, 2020 #28

    michael Hille

    michael Hille

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    Awesome thanks for the idea Will look at that and see if I can include.
     
  9. Jan 29, 2020 #29

    michael Hille

    michael Hille

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    Be careful of using a wing that gets a lot of it's lift at high AOA. you can find yourself trying to rotate to an angle that puts the tail underwater. Hulled aircraft land and takeoff the water at much shallower angles than land planes, you need an airfoil that matches. I assume you have a copy of NACA Tech Note 2302 which defines what works and more importantly what does not as far as small seaplane design goes. Hull width to length,deadrise angle, tail volume, tail to keel angle and another hundred gotchas waiting for the unsuspecting seaplane designer.
    Just trying to shorten your learning curve, Ken Rand tried to convert his KR2 to amphib, disaster. With a pusher engine directly behind the cabin it is exceedingly difficult to keep the air flow around the cabin attached . As a result you get nasty flow into the prop. Look up Glass Goose and all the bandaids they tried to make it work. The Wider the cabin the harder it is to achieve. The Seabee makes it work (barely) but you can't use flaps on takeoff as it robs too much air from the prop.
    You have bitten off a BIG project, good luck with it. JohnB[/QUOTE]
    Thanks for the input John it is definitely a big project and challenging learning curve . The cabin hull section will have a nose down attitude in flight to counteract the wing angle of attack a bit like a SEAREY. I have two SEAREY aircraft in the hanger that helped with the design a bit too.Thanks for your help , if you have any more things you can think of please let me know. Definitely need the help and advice from everyone to make this happen
     
  10. Jan 29, 2020 #30

    michael Hille

    michael Hille

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  11. Jan 29, 2020 #31

    michael Hille

    michael Hille

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    Thanks for that I will look it up And do the research
     
  12. Jan 29, 2020 #32

    michael Hille

    michael Hille

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    Thank you for the input, I hadn’t thought about the engine flying into the pilots head until today after this comment so that’s one thing I will be looking at as safety is a major factor the whole fuselage and hull will essentially be one piece having the tail boom go right through the forward hull to act like a boxed beam to strengthen the hull where the water impact will be Think of it like a large centre console 200mm wide through the center of the whole aircraft
     
    Last edited: Jan 29, 2020
  13. Jan 29, 2020 #33

    Johan Fleischer

    Johan Fleischer

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    Hi Michael. What software are you using to make those drawings? (Screendumps)
     
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  14. Jan 29, 2020 #34

    dog

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    The thread that deals with that is DESIGN FOR SAFTEY, (all capps),it has some posts and links and examples of pusher planes that have faired well in accidents.
    specificaly the centerline thrust cesena (337)and also some reference to the sea bee, republic was renouned for building realy tough planes.
    Both of those have long service historys and drawings to peruse wont be impossible to find.
     
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  15. Jan 29, 2020 #35

    wktaylor

    wktaylor

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    May want to take a peek at these... lotta info RE seaplane/floatplane/amphibian design that is not necessarily 'obvious'... just saying...

    MIL-A-8864 Airplane Strength and Rigidity - Water and Handling Loads for Seaplanes
    NAS807 Specification - Twin Seaplane Floats
    ASTM F2245 Standard Specification for Design and Performance of a Light Sport Airplane
    ASTM F3061 Standard Specification for Systems and Equipment in Small Aircraft
    ASTM F3065 Standard Specification for Aircraft Propeller System Installation
    ASTM F3116 Standard Specification for Design Loads and Conditions
    ASTM F3173 Standard Specification for Aircraft Handling Characteristics
    ASTM F3179 Standard Specification for Performance of Aircraft
    ASTM F3234 Standard Specification for Exterior Lighting in Small Aircraft
    ASTM F3264 Standard Specification for Normal Category Aeroplanes Certification
    ASTM F3331 Standard Practice for Aircraft Water Loads
    EF Bruhn - Analysis and Design of Flight Vehicle Structures [seaplane structural aspects]

    BTW... curious if You have gotten this far, yet...
    Fresh water, salt-water, brackish water or all-water conditions?
    Operational design for 'sea conditions/states'?
    What aluminum alloys are You proposing? External and internal corrosion protective finishes?
    Fusion welding with filler-metal or 'excess flange with 'melt-down'? or both?
    Welding inspection/NDI criteria? Visual, penetrant, etc?
    Are You going to weld-on or fasten-on debris impact keel/shields/skids?
    Condensation leakage paths and drain-paths and bilge water removal? [All structures and systems elements]

     
    Last edited: Jan 29, 2020
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  16. Jan 29, 2020 #36

    michael Hille

    michael Hille

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    Thanks for the info I will definitely check it out
     
  17. Jan 29, 2020 #37

    michael Hille

    michael Hille

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    Thank you very much for the info I have read some of them already however there are a few that I haven’t. My background is mechanical engineering so I love all this stuff
    To answer some of your questions I will be going for all water conditions
    The aluminium I will be using is 6061-T6 the welding will be fusion Tig welded with filler rod as excess flange with melt down has a tendency to crack the hull will have a welded keel shield centre strakes welded on and internal boxed beam back bone for strength welding inspection will be visual. Water removal will be through a bilge and drain at bottom of the step with large quick release inspection panels to wash out salt even right up the boom I’m going for a design that can be washed inside and out after salt operations . Corrosion protection will be sprayed inside and out ( float lacquer) Prior to assembly and joints will also have a very thin film of polyurethane sealant during final assembly to stop ingress of moisture. Then coated with boiled linseed oil and finally a water disperse spay coverage after a wash .
     
  18. Jan 29, 2020 #38

    michael Hille

    michael Hille

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    I use fusion 360 , It’s a very user friendly program and has stress analysis and all the good stuff you need
     
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  19. Jan 31, 2020 #39

    Johan Fleischer

    Johan Fleischer

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    Thank you. I am considering learning Fusion 360 myself :)
     
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  20. Jan 31, 2020 #40

    TarDevil

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    Michael, thanks for the pictures and commentary. I can't do YouTube during the day but can sneak in a read once in a while. Good work, looking forward to your progress.
     
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