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An amphibian that sank?



 
 
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  #11  
Old April 24th 06, 12:29 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?

The only unsinkable boat I know about is the Boston Whaler
www.whaler.com which is made of two fiberglass shells bonded
together with the inside filled 100% with foamed in-place
resin that makes it one solid boat. They even can be cut
into sections and the still get you to shore with dry feet.

But aluminum floats don't work well with foam inside because
of corrosion between the foam and metal. A better solution
is to fill the compartments with ping-pong balls. They
displace water, don't weigh too much and can be removed for
inspection and corrosion control.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"Morgans" wrote in message
...
|
| "Flyingmonk" wrote in message
|
ups.com...
| http://www.divingservices.net/aircraft.jpg
| http://www.divingservices.net/9bcess2.jpg
|
| Anyone have the story behind this? Strange that a plane
designed to
| float, sank!
|
| You might be surprised how many recreational boats sink.
There are dozens
| of thing that can happen. Most common are drain plug left
out/loose, seals
| or hoses leaking and slowly filling the boat.
| --
| Jim in NC
|


  #12  
Old April 24th 06, 12:39 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?

In article ,
"Morgans" wrote:

"Roy Smith" wrote

One of the fundamental truths of boat design is that the center of gravity
has to be lower than the center of bouyancy. If it's not, then eventually
the boat (helicopter, whatever) will figure out how to turn itself over so
that it is.


Not completely true, but right to a degree.

In the case of a heli or plane on floats, the center
of gravity is way higher than the center of buoyancy,
and everything continues to work out OK.

In that case the center of gravity is between the
outer points of buoyancy. Like this:


GGG

BB BB

Then if it gets a little sideways, and the gravity
is on the outside of buoyancy, things will re-adjust.

GGG BB

BB

Ker-splash! Soon it is stable again, but
in a bad (g) way:

BB BB

GGG


Exactly. The heli has indeed figured out how to turn itself over and put
its CG below its CB.
  #13  
Old April 24th 06, 01:19 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?

The only unsinkable boat I know about is the Boston Whaler
www.whaler.com which is made of two fiberglass shells bonded
together with the inside filled 100% with foamed in-place
resin that makes it one solid boat. They even can be cut
into sections and the still get you to shore with dry feet.

But aluminum floats don't work well with foam inside because
of corrosion between the foam and metal. A better solution
is to fill the compartments with ping-pong balls. They
displace water, don't weigh too much and can be removed for
inspection and corrosion control.


--
James H. Macklin
ATP,CFI,A&P

Some of the small sail boats also have foam filled compartments with the
same effect. The name MacGreggor comes to mind from years ago, and there
are probably others by now.

Peter


  #14  
Old April 24th 06, 01:50 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?

Roy Smith wrote:

One of the fundamental truths of boat design is that the center of gravity
has to be lower than the center of bouyancy. If it's not, then eventually
the boat (helicopter, whatever) will figure out how to turn itself over so
that it is.


Absolutly wrong. The center of bouyancy of most large boats and ships
is well below the center of gravity.

--
John (I Took Naval Science) Kimmel


GET YER STINKING PAWS OFF ME YOU DAMN DIRTY APE!
  #15  
Old April 24th 06, 02:00 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?

"Peter Dohm" wrote:
Some of the small sail boats also have foam filled compartments with the
same effect. The name MacGreggor comes to mind from years ago, and there
are probably others by now.


Barf. Never use "MacGregor" and "sailboat" in the same sentence. They are
the most butt-ugly things in the universe.
  #16  
Old April 24th 06, 02:18 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?


John Kimmel wrote:
Roy Smith wrote:

One of the fundamental truths of boat design is that the center of gravity
has to be lower than the center of bouyancy. If it's not, then eventually
the boat (helicopter, whatever) will figure out how to turn itself over so
that it is.


Absolutly wrong. The center of bouyancy of most large boats and ships
is well below the center of gravity.

--
John (I Took Naval Science) Kimmel


GET YER STINKING PAWS OFF ME YOU DAMN DIRTY APE!


I saw a head-on picture of a carrier and boy did it look top heavy...

The Monk
GET YER STINKING PAWS OFF ME YOU DAMN DIRTY HUMAN! ~ Panet of the Apes
II

  #17  
Old April 24th 06, 02:19 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?

"Grumman-581" wrote in message
...
"Roy Smith" wrote in message
...
23.751 Main float buoyancy.

(a) Each main float must have
[...]


I don't see anything in there that would require the supposedly watertight
compartments to still provide floatation in the event of them no longer
being watertight...


There's not.

However, I have heard of seaplane owners who have done things like fill
their wings (or other easily accessed compartments) with ping-pong balls,
for this purpose.

Generally speaking though, seaplanes don't have any filler material, such as
styrofoam or what have you the way boats do. I think it's likely that this
is because, as light as styrofoam is, when you fill every empty space of an
airplane with it, that's still useful load you lose.

Of course, there are also the certification and maintenance issues as well.
The bottom line is, I believe, that it's much simpler to put a bunch of
lightweight filler material in a boat than in an airplane.

Pete


  #18  
Old April 24th 06, 02:36 AM posted to rec.aviation.piloting,rec.aviation.homebuilt
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Default An amphibian that sank?

"Roy Smith" wrote in message
...
"Peter Dohm" wrote:
Some of the small sail boats also have foam filled compartments with the
same effect. The name MacGreggor comes to mind from years ago, and

there
are probably others by now.


Barf. Never use "MacGregor" and "sailboat" in the same sentence. They

are
the most butt-ugly things in the universe.


They actually did have a replica of a 19th century pilot boat that I thought
was sort of neat, if less than practical, and commercially it was a dismal
failure. But I really don't like most of their competitors boats very much
either.

Peter


  #19  
Old April 24th 06, 02:48 AM posted to rec.aviation.homebuilt
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Default An amphibian that sank?

On 23 Apr 2006 13:56:44 -0700, "Flyingmonk" wrote:

Anyone have the story behind this? Strange that a plane designed to
float, sank!


Friend of mine had built an Osprey II amphibian and planned to make its first
flight from the water instead of land. He took it down the seaplane ramp for
water-taxi testing. A few minutes after hitting the lake, he noticed water
sloshing around on the bottom of plane. When he'd gone down the seaplane ramp,
the nose of the plane had pitch up when it hit the water, ramming the tail skid
into the fuselage and leaving a bit of a large hole.

He poured on the power to go back to the ramp. When he got close, he cut power
and flipped the Armstrong gear lever. But when the gear hit the ramp, the mains
collapsed. Turns out the primary landing gear torque tube had been undersized
(design error).

My buddy paid for a forklift to carry his plane back to the hangar. There, he
set the bottle jack under the wing to jack the plane up so that he could lower
the gear back down. The jack slipped, punching a hole in the bottom of the
wing.

Amphibians CAN sink...and even if they float, the day ain't over yet. :-)

Ron Wanttaja
  #20  
Old April 24th 06, 02:56 AM posted to rec.aviation.homebuilt
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Default An amphibian that sank?



Ron Wanttaja wrote:


Friend of mine had built an Osprey II amphibian and planned to make its first
flight from the water instead of land. He took it down the seaplane ramp for
water-taxi testing. A few minutes after hitting the lake, he noticed water
sloshing around on the bottom of plane. When he'd gone down the seaplane ramp,
the nose of the plane had pitch up when it hit the water, ramming the tail skid
into the fuselage and leaving a bit of a large hole.

He poured on the power to go back to the ramp. When he got close, he cut power
and flipped the Armstrong gear lever. But when the gear hit the ramp, the mains
collapsed. Turns out the primary landing gear torque tube had been undersized
(design error).

My buddy paid for a forklift to carry his plane back to the hangar. There, he
set the bottle jack under the wing to jack the plane up so that he could lower
the gear back down. The jack slipped, punching a hole in the bottom of the
wing.


Sounds like it was time to go get a beer and come back
another day. Its always a good thing to know when you're
whupped

Don W.

 




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