Experimental sea plane please follow along

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michael Hille

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Joined
Aug 14, 2019
Messages
61
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.
Thanks for that I will keep you all updated I’m currently working on the mdf sheet still , after someone’s comment on airflow detachment from the hull I am Changing the shape slightly to a better nicer curve to help with airflow around to the prop
 

Himat

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Joined
May 5, 2011
Messages
2,861
Location
Norway
First a reference Snorri Gudmundsson have written the textbook “General Aviation Aircraft Design, Applied Methods and Procedures”. “APPENDIX C3 – DESIGN OF SEAPLANES 1” was released as a PDF on internet after the book was out. This is one of the few recent texts on seaplane design and of the better I have seen. Not that much on hydrodynamic design, but at least references to the 1950’ies NACA papers.

Then some comments about hull design. It is common to design the hull with the step 10 to 15 degrees behind the aircraft centre of gravity. Not a hard requirement, but usually the easy way to make a working design. A long narrow hull gives less of a planning “hump” drag and pounding force in waves.

Step height and afterbody rise must be designed together with the wing to minimise porpoising and let the airplane rotate max lift, almost stall on take-off.

Floating static, it is an idea to match side area and drag in such a way that the plane weathervane a little into the wind. The other way around is inconvenient in operation.

Actually, design choices that have operational consequences are important. That is how easy is it dock and beach the airplane and get into and out of.
 

michael Hille

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Joined
Aug 14, 2019
Messages
61
First a reference Snorri Gudmundsson have written the textbook “General Aviation Aircraft Design, Applied Methods and Procedures”. “APPENDIX C3 – DESIGN OF SEAPLANES 1” was released as a PDF on internet after the book was out. This is one of the few recent texts on seaplane design and of the better I have seen. Not that much on hydrodynamic design, but at least references to the 1950’ies NACA papers.

Then some comments about hull design. It is common to design the hull with the step 10 to 15 degrees behind the aircraft centre of gravity. Not a hard requirement, but usually the easy way to make a working design. A long narrow hull gives less of a planning “hump” drag and pounding force in waves.

Step height and afterbody rise must be designed together with the wing to minimise porpoising and let the airplane rotate max lift, almost stall on take-off.

Floating static, it is an idea to match side area and drag in such a way that the plane weathervane a little into the wind. The other way around is inconvenient in operation.

Actually, design choices that have operational consequences are important. That is how easy is it dock and beach the airplane and get into and out of.
Thank you very much for the info , I will incorporate the suggestions into the design ,based on his I will need to move the step back slightly. No major issue though
 

dog

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Joined
Dec 29, 2019
Messages
240
Snorri Gudmundsson have written the textbook “General Aviation Aircraft Design, Applied Methods and Procedures”. “APPENDIX C3 – DESIGN OF SEAPLANES 1” was released as a PDF on internet

Floating static, it is an idea to match side area and drag in such a way that the plane weathervane a little into the wind.

Actually, design choices that have operational consequences are important.


Second the thanks for the link to the Design of Seaplanes,have gone through it twice at speed, and will now go through much more slowly
running some of the equasions.
 

Lendo

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Joined
Feb 6, 2013
Messages
406
Location
Brisbane
Himat, GAAD is an excellent Text, I did however find errors in some of the examples, please just consider this a heads-up.
George
 

michael Hille

Well-Known Member
Joined
Aug 14, 2019
Messages
61
First a reference Snorri Gudmundsson have written the textbook “General Aviation Aircraft Design, Applied Methods and Procedures”. “APPENDIX C3 – DESIGN OF SEAPLANES 1” was released as a PDF on internet after the book was out. This is one of the few recent texts on seaplane design and of the better I have seen. Not that much on hydrodynamic design, but at least references to the 1950’ies NACA papers.

Then some comments about hull design. It is common to design the hull with the step 10 to 15 degrees behind the aircraft centre of gravity. Not a hard requirement, but usually the easy way to make a working design. A long narrow hull gives less of a planning “hump” drag and pounding force in waves.

Step height and afterbody rise must be designed together with the wing to minimise porpoising and let the airplane rotate max lift, almost stall on take-off.

Floating static, it is an idea to match side area and drag in such a way that the plane weathervane a little into the wind. The other way around is inconvenient in operation.

Actually, design choices that have operational consequences are important. That is how easy is it dock and beach the airplane and get into and out of.
This paper has some awesome information thank you so much for sharing it took a bit to find but worth a read
 

Riggerrob

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Joined
Sep 9, 2014
Messages
1,282
Location
Canada
Some sources say that both step and main wheels should be 17 degrees aft of the centre of gravity. That probably depends upon tip-back angles when the cockpit is un-occupied.
 

michael Hille

Well-Known Member
Joined
Aug 14, 2019
Messages
61
Some sources say that both step and main wheels should be 17 degrees aft of the centre of gravity. That probably depends upon tip-back angles when the cockpit is un-occupied.
Thanks for that , I’m working on double checking the step location so this is useful information
 
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