Ocean Ditching

[schurch379]

I am a private pilot with about 400 hrs of flying in Hawaii, and shipped a 2009 CTLS to Hawaii mid-year. It's a great plane, just about perfect for Hawaii flying.

 

Anyway, my flights are over the ocean the majority of my flying, i.e., inter-island trips and routes. Now; I am not paranoid about having to pull the BRS and land in the ocean, and am well prepared for this eventuality; however, the thought recently struck and hence, I was interested in whether or not the CTLS had enough buoyancy in its wings to stay on top of the water, rather than sinking ( if ditched )?

 

Any opinions out there? )

 

Scott

Kona, Hawaii

[Anticept]

That's something I've been trying to figure out for a while. I think it will float though. There's a lot of foam in the structure that will hold air, and the fuel tanks and outboard empty air spaces only have drain holes on the bottom, so it should be enough, at least for a while.

[Ian]

Scott - what's the average water temperature in your area? Do you carry a life-raft or anything in addition to a life-jacket?

 

I don't know the answer to your original question, I'd guess as Anticept suggests that it will float for a while.

[Roger Lee]

It would easly long enough to exit. How long it stays up is anybody's guess. I hope you keep a life jacket on board.

[Ian]

...... and the carbon fiber has good buoyancy too. .......

 

I'm struggling with that one - the density of water is of course 1g/cc - Carbon Fibre is 1.6g/cc - Put a piece of carbon fibre in water and it will sink.

[FlyingMonkey]

The wing tanks are sealed and would act as perfect floation for the whole plane. Plus the plane itself in incredibly light, and the carbon fiber has good buoyancy too. No doubt the plane would float for a good while dependent upon how much fuel displaces air in those tanks.

 

Even with empty tanks, the fuel vents on top could take on water. Also, if the fuel valve is open and the engine is under water, water could push *up* through the fuel lines and fill the tanks. It would be smart to close the fuel valve before ditching anyway, but that's another good reason.

[Anticept]

The wing tanks are sealed and would act as perfect floation for the whole plane. Plus the plane itself in incredibly light, and the carbon fiber has good buoyancy too. No doubt the plane would float for a good while dependent upon how much fuel displaces air in those tanks.

 

Carbon fiber and epoxy sinks. It's the foam that floats. Anyways it should float for a little while, but as for STAYING afloat, I don't have any data for that. The tanks do have vents, but the way the vents route (they go from the outboard edge of the tank, inwards to the root, and back out to the winglet) and the crossover tube, it will resist filling for a while. They will eventually fill with water though unless it stays balanced.

 

I'm going to ask FD.

[FlyingMonkey]

It will float as long as it displaces 1320 pounds of water, about 158 gallons.

 

Archimedes to the rescue!

[Ian]

Archimedes to the rescue!

 

Eureka!!

[Ian]

You do not account for the layering of the carbon fiber sheets which leave small air gaps in the substructure. Betcha a chunk of a CTLS skin will float pretty well. One good way to test it is to take off a baggage door and put it in a tub of water. It will float, no dout.

 

Want to try it & post the photos?

 

I'll bet you it sinks - though how we ever collect the bet, who knows?

[Anticept]

You do not account for the layering of the carbon fiber sheets which leave small air gaps in the substructure. Betcha a chunk of a CTLS skin will float pretty well. One good way to test it is to take off a baggage door and put it in a tub of water. It will float, no dout.

 

It has miniscule air bubbles. Air bubbles in composite construction are BAD. VERY BAD. When you mix epoxy, it is supposed to be stirred gently, not whipped. Then when you lay it up, you have to press the epoxy into the layers to displace as much air as possible. Flight design uses pre-preg construction methods, where each layer is individually impregnated with epoxy. Then it is layed, then vacuum bagged to draw out air and excess epoxy. It's the foam that has the biggest effect, not the few air bubbles in the epoxy suspension. I have some samples of carbon fiber and epoxy that don't have any foam in them at school, I'll see if they float. I strongly suspect they won't, but I've been wrong before.

 

The fuel vents are high up on the top of the winglets far above the wing. And they are pinholes that likely would not allow water in much if at all. The tires are also floatation devices. And so are the lower fin, elevator and tail, all are hollow.

 

The plane will lower one wing to the water's surface once ditched. Stating that the tires will act as flotation devices doesn't do what you think it does: they will try to roll the plane over. Also, I've spilled fuel out of those vents during an A&P class when they asked me to bring my plane so they can see how much it weighs. We did it with full tanks. When I lifted up one wing so they could slide a scale under the wheel, then went to the other side, fuel started spilling out that got trapped in the line. They may be small, but you would be surprised at how quickly fluid can flow. I'm not saying the tanks will be flooded as soon as dew collects on the wing, but I doubt the plane will be on the surface tomorrow if the fuel tanks are the only things keep it floating.

[Rich]

Schurch,

 

Assuming the plane stays together in a water landing. Landing in water is very different from landing with the chute on land.

On land, the landing gear absorbs much of the initial shock. Not so in water. The gear goes through the water and the CT's fuselage will take the full force, followed by the wings, if they're still attached.

 

Spinal injury is almost certain but in an emergency, I guess it's he best choice with fixed gear.

 

I wear SOSpenders with the CO2 manual inflator when flying over water, just as a back up

[FastEddieB]

 

Assuming the plane stays together in a water landing. Landing in water is very different from landing with the chute on land.

On land, the landing gear absorbs much of the initial shock. Not so in water. The gear goes through the water and the CT's fuselage will take the full force, followed by the wings, if they're still attached.

 

Spinal injury is almost certain but in an emergency, I guess it's he best choice with fixed gear.

 

This is definitely worth a read to put a variety of things in perspective:

 

http://www.avweb.com/news/features/190126-1.html?redirected=1

[Anticept]

Schurch,

 

Assuming the plane stays together in a water landing. Landing in water is very different from landing with the chute on land.

On land, the landing gear absorbs much of the initial shock. Not so in water. The gear goes through the water and the CT's fuselage will take the full force, followed by the wings, if they're still attached.

 

Just wanted to add: fixed gear planes can flip in water if you land them (without a parachute). In fact, this is one of those moments where it's good to be practiced up on your full stall landings!

[FastEddieB]

Anything will float if it's water tight and displaces more water than it's weight. A metal plane will float as easily as any other. A concrete plane will float if it's big enough, although it might not fly.

 

You're forgetting the fact that the carbon fiber in CTLSi's plane is infused with magic pixie dust, rendering it superior to every other plane on the market in every possible way.

 

Can we just stipulate that and move on???

[Doug G.]

If I understand the question correctly the "ditching" would come after the chute was deployed. The Slashdot should be relatively benign. I think the question has to do with how long you have to get out, and how long someone would have to reach you before the ship sank.

[Duane Jefts]

Schurch 379

 

I flew search and rescue out of Hawaii for a few years and saw all different kinds of airplanes land in the water. Never something you want to do.

 

If you try to land it, you will probably be upside down when you come to the sudden stop. The shoulder straps are not the best in a CTLS so good luck on not banging your head.

 

I would recommend using the chute, but keep in mind when the airplane floats down and enters the water, you will probably be exiting under water. I would have the door cracked with something in it to keep it from closing on you like a jacket.

 

Have a vest on and your flares/mirror etc.. in the vest. Do this every time you fly. Good to have an ELT and/or radio with you as well.

 

This is just a quick and dirty but the best measure is altitude between Islands and stay within gliding distance if possible.

 

Most airplanes I have seen land in the water with low wings float upright; high wing planes also float but upside down.

[schurch379]

Thanks to everyone for your opinions and thoughts.

 

One of you even directed me to a website providing a description by a Cirrus owner with parachute deployment and landing in the Hudson river. It was a very rough landing, with some compressed fractures, etc., and provided an excellent comparative situation. Here are my thoughts:

 

As to the impact, the Cirrus deploys the chute such that the airplane is in a level condition. It also it has low wing. This combination understandably produced an immediate stoppage of descent upon impact with the water, with no absorption and softening by landing struts worsened by the wings. No surprise that there was spinal compression.

 

The Flight Design CTLS, as I understand, deploys such that the fuselage has a slight nose-down angle. This combined with the high wing should produce two differences compared with the Cirrus water ditching: 1) the nosewheel and fuselage will most likely strike the water first, and plow into it, the shoulder harness absorbing a material amount of the overall impact by halting forward inertia, as the descent impact per se, is reduced by the fuselage partially submerging. 2) the high wing will only impact after much of the energy has been absorbed and dissipated in the water and fuselage. 3) because I contemplate any ditching with the gull wing doors open, upon impact the water will rush in quickly to further decelerate impact. Quickly thereafter, release should harness, and exit, perhaps from slightly under water.

 

As to the floatation question, after thinking through all the good input, here is what I conclude: due to trade winds, and uncontrolled centerline direction upon impact, at a decent of 17ft / sec it is as likely as not that one of the wings would strike the water, or a wave crest ( as it is the fuselage would strike first ). If the wing strikes first, i doubt it would break, but it is entirely possible the that the plane flips. Regardless, presuming safe exit, the plane should indeed submerge only partially, but not completely, and give something to hang onto for least for a couple of hours due to the various air spaces and lower density of various spaces.

 

In my situation, I have all the safety tools one can have with me, and also fly conservative routes, which places me within gliding distant of a Hawaiian airport about 50% of the time. So, in conclusion, I want to thank you all for your input, on a topic which clearly stirred some interest and comment. If you are in Kona, give me a call 808 989 5967, and we will give it a go firsthand !

 

Scott

Kona, Hawaii

[WmInce]

. . . "One thing for sure" . . .

 

There is nothing sure about your assertion.

[WmInce]

. . . "Most airplanes I have seen land in the water with low wings float upright; high wing planes also float but upside down." . . .

 

In my book . . . that's a "biggy."

[Dan Kent]

In my opinion it will float if the wings stay water tight. From the FD website the wing area is about 94 ft^2 (portions outboard of the fuselage). 1320 lbs/62.4 lbs/ft^3 (density of fresh water) would mean you would need more than 21.2 ft^3 of water displacement to float. Assuming all of this displacement was from the wings only, would mean that the average depth of the wing would need to be about 3".

[Marco01]

There is a story here in france of an ultralight crash between France and Corsica: pilote open the chute, was rescued by a fisher, and got back his plane 2 weeks later! so yes it floats well!

http://www.nicematin.com/article/un-ulm-sabime-en-mer-a-60-km-au-large-de-nice.635189.html

http://www.corsematin.com/article/calvi/lulm-perdu-en-mer-au-large-de-nice-secouru-par-la-snsm.476011.html

[Karl]

There is a story here in france of an ultralight crash between France and Corsica: pilote open the chute, was rescued by a fisher, and got back his plane 2 weeks later! so yes it floats well!

http://www.nicematin.com/article/un-ulm-sabime-en-mer-a-60-km-au-large-de-nice.635189.html

http://www.corsematin.com/article/calvi/lulm-perdu-en-mer-au-large-de-nice-secouru-par-la-snsm.476011.html

That looks like a pipistrel from what's is showing above the water line.

The pipistrel is build using similar materials and process so I go with that a CT should float.

[Doug G.]

Hmm... and it is not upside down.

[Duane Jefts]

Hmm... and it is not upside down.

My post said if a high wing airplane LANDS in the water it will more that likely be upside down. If I think I will end up in the water, I'll use the BRS and in that case it should end up right side up and floating.

 

The high wing plane referenced above looks llike it went in the water with a chute deployed.