An amphibian that sank?

"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!


Doesn't seem any stranger than a boat sinking. I believe they're designed
to float as well.

"Steven P. McNicoll" wrote in message
ink.net...
Doesn't seem any stranger than a boat sinking. I believe they're designed
to float as well.

These days, smaller boats often have flotation chambers filled with a closed
cell type foam (e.g. styrofoam) so that in the even that they are filled
with water, they might still remain on the surface, dependent upon what else
might be loaded in the boat... It wasn't always that way though... I've
helped recover sunken boats before that sank after hitting logs and such and
knocking holes in their bottom... Larger boats aren't required to have this
sort of positive flotation though... Don't remember exactly at what length
the requirement no longer applies... Probably around 25-30 ft or so, I
guess... It's quite possible that amphibs don't have this sort of design in
them...

In article ,
"Grumman-581" wrote:

"Steven P. McNicoll" wrote in message
ink.net...
Doesn't seem any stranger than a boat sinking. I believe they're designed
to float as well.

These days, smaller boats often have flotation chambers filled with a closed
cell type foam (e.g. styrofoam) so that in the even that they are filled
with water, they might still remain on the surface, dependent upon what else
might be loaded in the boat... It wasn't always that way though... I've
helped recover sunken boats before that sank after hitting logs and such and
knocking holes in their bottom... Larger boats aren't required to have this
sort of positive flotation though... Don't remember exactly at what length
the requirement no longer applies... Probably around 25-30 ft or so, I
guess... It's quite possible that amphibs don't have this sort of design in
them...

*23.751***Main float buoyancy.

(a) Each main float must have‹

(1) A buoyancy of 80 percent in excess of the buoyancy required by that
float to support its portion of the maximum weight of the seaplane or
amphibian in fresh water; and

(2) Enough watertight compartments to provide reasonable assurance that
the seaplane or amphibian will stay afloat without capsizing if any two
compartments of any main float are flooded.

(b) Each main float must contain at least four watertight compartments
approximately equal in volume.

"Roy Smith" wrote in message
...
23.751 Main float buoyancy.

(a) Each main float must have

(1) A buoyancy of 80 percent in excess of the buoyancy required by that
float to support its portion of the maximum weight of the seaplane or
amphibian in fresh water; and

(2) Enough watertight compartments to provide reasonable assurance that
the seaplane or amphibian will stay afloat without capsizing if any two
compartments of any main float are flooded.

(b) Each main float must contain at least four watertight compartments
approximately equal in volume.

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...

On a side note, I've heard that for emergency floats on offshore (oil rig)
helicopters, they often end up with the floats on the surface and the
helicopter suspended underneath it in the water..

In article ,
"Grumman-581" wrote:

On a side note, I've heard that for emergency floats on offshore (oil rig)
helicopters, they often end up with the floats on the surface and the
helicopter suspended underneath it in the water..

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.

"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
--
Jim in NC

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.

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
--
Jim in NC

Uh, Houston, we are in Stable -two.

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!

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