Why not foam?

Dav8or

Dav8or

Final Approach
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Jan 6, 2007
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Discovery Bay, CA
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Dave
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C83 Byron, CA
Airplanes often fly distances over water. Airplanes sometimes lose engine power over water and end up in the water. There they usually sink, but airplanes are full of empty cavities that go unused. Plastic foam is very light. Why not fill those cavities with foam so the plane could turn into a raft??
 
The pylons/pontoons of the spruce goose were filled with beach balls...
 
BUUUT that's a lot of weight that adds up for something that 99% of aircraft aren't going to be in a situation to use. Enough foam to keep it to float would be a good bit of weight that takes away from useful load etc.
 
Dav8or said:
Airplanes often fly distances over water. Airplanes sometimes lose engine power over water and end up in the water. There they usually sink, but airplanes are full of empty cavities that go unused. Plastic foam is very light. Why not fill those cavities with foam so the plane could turn into a raft??
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The largest cavity is the one needed for payload. If it is not watertight, and remains so after the ditching, that flooded compartment will likely overcome any buoyancy from foam filled extremities.
[Think of the Titanic, with 16 watertight compartments. As the forward 6 flooded it was enough to drag the ship to the bottom]

Amphibian airplanes like the Lake Buccaneer or Renegade have a watertight hull for buoyancy...which shows that foam isn't needed to create an airplane that will float.
 
The foam would trap water resulting in corrosion. Also, not as light as you would think, so the problems outweigh the limited benefits.
 
Problem is, the engine is the heavy part and it is way out front, When you make any other part of the A/C buoyant it floats tail up. Where would you set?
 
GRG55 said:
The largest cavity is the one needed for payload. If it is not watertight, and remains so after the ditching, that flooded compartment will likely overcome any buoyancy from foam filled extremities.
[Think of the Titanic, with 16 watertight compartments. As the forward 6 flooded it was enough to drag the ship to the bottom]
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Water has neutral buoyancy in water. Just because the airplane has cavities filled with water doesn't mean it has to sink. It simply has to displace enough water to compensate for its weight.

I think it is impractical for airplane but it is a neat idea. The biggest problem would be keeping the airplane together when making an emergency landing in the water especially in rough seas.
 
As most know I live in an area that has lots of water to fly over, I have seen a few owners that carry a raft, I always ask, "how are you going to get it out of the baggage area, and deploy it prior to the aircraft sinking" always get a blank stare.
 
Joshuajayg said:
Water has neutral buoyancy in water. Just because the airplane has cavities filled with water doesn't mean it has to sink. It simply has to displace enough water to compensate for its weight.

...
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I am aware of that. Do you seriously think that if the cabin area is flooded the remaining volume in a typical GA aircraft shape can displace enough seawater to keep it afloat? Not having done the volumetrics I can't say with certainty, but I do have my doubts.
 
Tom-D said:
As most know I live in an area that has lots of water to fly over, I have seen a few owners that carry a raft, I always ask, "how are you going to get it out of the baggage area, and deploy it prior to the aircraft sinking" always get a blank stare.
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Not all planes sink immediately. Usually there's 30 seconds or so. Que video of cirrus that parachuted into the pacific on the way to Hawaii, floated for a while.
 
GRG55 said:
I am aware of that. Do you seriously think that if the cabin area is flooded the remaining volume in a typical GA aircraft shape can displace enough seawater to keep it afloat? Not having done the volumetrics I can't say with certainty, but I do have my doubts.
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Wouldn't that depend upon if the fuselage was a pressurized type?
 
Are you wanting the cavities filled with foam all the time or just in case of ditching. If all the time, so much for internal structural inspections. If just in case of ditching, you have to add the system and what happens when it's activated by accident?
 
Mtns2Skies said:
Not all planes sink immediately. Usually there's 30 seconds or so. Que video of cirrus that parachuted into the pacific on the way to Hawaii, floated for a while.
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Can you get every one out, the baggage area open, then drag out a raft in 30-60 seconds?
 
Tom-D said:
As most know I live in an area that has lots of water to fly over, I have seen a few owners that carry a raft, I always ask, "how are you going to get it out of the baggage area, and deploy it prior to the aircraft sinking" always get a blank stare.
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That's why I make the wife hold it on her lap during the flight. ;)
 
GRG55 said:
I am aware of that. Do you seriously think that if the cabin area is flooded the remaining volume in a typical GA aircraft shape can displace enough seawater to keep it afloat? Not having done the volumetrics I can't say with certainty, but I do have my doubts.
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I think that with enough foam to offset the weight of the aluminum, yes. Now if an regular airplane got filled with water, no. That's why we are talking about foam.
 
Greg Bockelman said:
Are you assuming they would land pressurized? Probably not a good idea if you want to get out of it. Hard to open the door.
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I think he's thinking better quality seals and functional design that keeps air in would slow the ingress of water compared to a non pressurized aircraft.
 
Would some of the newer composite airplanes (thing DA 20/40 ETC) have a better chance of floating or staying afloat longer than a Cherokee or something?
 
GRG55 said:
T[snip]
[Think of the Titanic, with 16 watertight compartments. As the forward 6 flooded it was enough to drag the ship to the bottom]
[snip]
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To pick a nit (Hey! It's POA!) IF the remaining 10 compartments had remained air filled, the Titanic would not have sunk. The problem was as it tipped forward the water flowed over the partition into the next compartment, etc. They were only water tight up to somewhere around the deck line.

John
 
Why not just bring a couple cans of flex seal and seal everything up before you hit the water?
]
 
Now if foam is used as a structural component (think cheap RC airplanes) it could have some merit.
 
Greg Bockelman said:
Are you assuming they would land pressurized? Probably not a good idea if you want to get out of it. Hard to open the door.
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I was thinking about the miracle on the Hudson, the pressure vessel will be much more water tight than the non pressurized.
think about the PA-28 doesn't even have a rear fuselage bulkhead.
 
Sac Arrow said:
Now if foam is used as a structural component (think cheap RC airplanes) it could have some merit.
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Does that mean the Rutan canards will float? or the Glassairs?

One of the Velocitys was flat spun into the water during flight testing, and it floated.
 
You guys need to see an airliner with all its interior panels removed. The amount of plumbing and wiring and controls of various sorts is staggering, and it's all in those "empty" cavities. Filling those with foam would make inspections and maintenance first-class headaches, which means that they often wouldn't get done right, which would compromise the safety of the airplane---the opposite of what the foam was supposed to do.

And there's no way you'd displace enough water with the foam to support a million-pound 747 anyway.
 
Mtns2Skies said:
The pylons/pontoons of the spruce goose were filled with beach balls...
Click to expand...

Always thought filling floats with ping pong balls would be a interesting idea, don't weight much, good buoyancy, won't hold moisture and allows any water to go to the bildge for the pumps.
 
Filling the empty spaces in an airplane with foam would not work. You need access to those spaces and the cables need to be able to run free. If you want a plane that floats get a floatplane. Pressurized planes will definitely float WAY better than unpressurized planes. If it wont let in air, it wont let in water. But nothing beats a floatplane. But still, even after you ditch in a floatplane, you are bobbing around in the water presumably with no power. Better have a marine radio and know what channel to hail for help...
 
Or fill the empty areas with helium..???? Then if the engine quits, just slowly float to the destination....:rolleyes:

Man, I gotta get off the pain meds....
 
James331 said:
Always thought filling floats with ping pong balls would be a interesting idea, don't weight much, good buoyancy, won't hold moisture and allows any water to go to the bildge for the pumps.
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years ago, I helped marine services raise two boats off the bottom with a device he had that can pump ping-pong balls. worked great.
 
Just have everyone eat beans. Hot gas rises right?

 
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