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  #1  
Old 09-29-2012, 01:00 PM
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Captain_John Captain_John is offline
 
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Default Will it float?!?

Hey all, ingot these really cool Class V PFD's for flying over water. A good thing to have just in case.

Anyways, I got to wondering how long an RV might float for?

I was told once that a warrior would float for like 15-30 minutes. That was hearsay and I am not sure that it is even correct.

Does anyone here have any real experience with this type of thing?

...not that you want to go out and test such a thing!

CJ
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  #2  
Old 09-29-2012, 01:12 PM
Michael Henning Michael Henning is offline
 
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Default

It would depend on how nicely you put it onto the water. If you start tearing the structure, particularly the wings, it will sink pretty quick.
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  #3  
Old 09-29-2012, 01:18 PM
evmeg evmeg is offline
 
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If you go into the water because your tanks are empty it may float....otherwise it will go down like an anchor. There was one a while back that went into the water in Hawaii and as I recall that guy said by the time he got the canopy open he was swimming for the surface. The thread is probably archived here somewhere.
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  #4  
Old 09-29-2012, 02:03 PM
Kyle Boatright Kyle Boatright is offline
 
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Location: Atlanta, GA
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Default

Quote:
Originally Posted by Captain_John View Post
Hey all, ingot these really cool Class V PFD's for flying over water. A good thing to have just in case.

Anyways, I got to wondering how long an RV might float for?

I was told once that a warrior would float for like 15-30 minutes. That was hearsay and I am not sure that it is even correct.

Does anyone here have any real experience with this type of thing?

...not that you want to go out and test such a thing!

CJ
There is a board member who experienced a ditching in a zero fuel Cherokee. It didn't float for long, IIRC.

One way to think about it is that the typical RV weighs 1100 pounds. That means it takes 1100 pounds of buoyancy to support it. 40 gallons of air in the tanks is 40 gallons x 8 lb/gallon = 320 lbs of buoyancy. So you need 800 pounds more buoyancy to stay afloat. The fuselage and wings may temporarily provide buoyancy, but they will fill pretty fast because of all of the gaps and holes in the structure. I wouldn't expect an RV to float very long.
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Last edited by Kyle Boatright : 09-29-2012 at 02:07 PM.
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  #5  
Old 09-29-2012, 02:13 PM
bkthomps bkthomps is offline
 
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Default

Quote:
Originally Posted by evmeg View Post
If you go into the water because your tanks are empty it may float....otherwise it will go down like an anchor. There was one a while back that went into the water in Hawaii and as I recall that guy said by the time he got the canopy open he was swimming for the surface. The thread is probably archived here somewhere.
fuel is more buoyant than water, the tanks will never be sealed when empty due to vents

this is one of the reasons the miracle in the hudson floated so well
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  #6  
Old 09-29-2012, 04:13 PM
DaAV8R DaAV8R is offline
 
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Default Floating

A Baron ditched in the Gulf a week or so back. Pilot reported that is sank in 2 minutes.
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  #7  
Old 09-29-2012, 10:29 PM
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Greg Arehart Greg Arehart is offline
 
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Just a thought - for those flying over water and worrying about such things, would it be worth putting styrofoam or somet similar closed-cell foam in the outboard wing bays or in the tail to help keep the airplane afloat longer? Shouldn't add much weight.

Greg
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  #8  
Old 09-29-2012, 11:01 PM
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Neal@F14 Neal@F14 is offline
 
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If the plane doesn't flip over as soon as the landing gear hits the water, and it lands mostly flat, the weight of the engine up front will pull the nose under water pretty quickly. I'd bet a typical RV would float for only a couple minutes max even if you ditched it perfectly, but hitting the water at 50+ mph is likely to tear enough places open in the aluminum to let the water in quickly.

ETA: Here's a real RV ditching story: http://www.vansairforce.net/articles/Ditching.htm
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  #9  
Old 09-30-2012, 10:23 AM
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Captain_John Captain_John is offline
 
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Mike, I agree. I have seen some "hydro-formed" Cessna parts. A compromise in the structure would allow the sinking process to happen faster.

I am in total agreement about the positive buoyancy effect of the AVGas however I am sure that empty tanks must be even more positive.

Greg, I bet that adding some floating foam wouldn't add much weight. Perhaps this stuff?

http://www.jamestowndistributors.com...ct.do?pid=2198

I wouldn't put it into my project because I don't plan on going swimming!

Hahaha

OTOH, if I had a little ultralight or microlight floatplane, I certainly would consider it!

Neal, I totally missed that story and am glad that you brought it to my attention! There is LOTS of great information there!

Once again, there is nothing new under the sun. I knew that there must have been some experience in this arena.

I am glad that it all turned out well for the pilot. I think that a reasonable approach to a buoyancy solution is the inflatable Class V PFD's that I have.

As a floatplane pilot, I know that capsiztic entrapment is a genuine concern. As a SCUBA diver, I think that I would be level-headed in such a situation. As a pilot, I know that some real training in that area would be a solid chioce in the right direction.

I know that Thermos (RV-7 builder here) has had precisely that training and he told me how invaluable it is. I totally agree.

Thanks All!!!

CJ
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  #10  
Old 09-30-2012, 01:04 PM
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RVG8tor RVG8tor is offline
 
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Default Survival Gear

Not on the subject of buoyancy but one clever RV builder and flyer I know put survival gear in vacuum backed bags in his wingtips. Sleeping bag, food, first aid etc. not much weight. It is always there and does not take up room in the baggage area. Pretty clever, nice to have some food and gear if you go in out in the boonies and survive.

Cheers
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