One problem with ditching articles / reports is that those who died (and many have) have not contributed data on what happened.
dublinpilot wrote:
A few years ago and aircraft went down going from the UK to the Channel Islands
If I remember the incident correctly, the aircraft was a twin as well. It’s not just singles that ditch.
Peter wrote:
If you find yourself literally underwater in a GA plane, you are dead, IMHO. It’s going to go straight down, fast.
I don’t think that’s true. I know someone who ditched a Twin Comanche in the Irish Sea. The ditching tore a big hole in the aft fuselage (in other words, there was a large hole where water could now enter). The plane remained afloat for long enough to egress and get into the life raft.
The stuff on equippedtosurvive shows there’s not really a difference in egress rates between high wing and low wing planes, fixed gear and retract.
What I meant was that once the entire plane is under the water surface then by definition there is no positive buyoancy, and then it will go straight down.
My take on this is that if you are still inside the cockpit once this happens, you won’t be getting out unless you manage to do it just in time.
Twins ditch quite often too, because of
What I meant was that once the entire plane is under the water surface then by definition there is no positive buyoancy, and then it will go straight down.
It may only sink as far as the pycnocline, not that there’s likely to be much of one in the English Channel.
However, when the (perhaps temporary) buoyancy of luggage, seats, cushions, tyres, struts, fuel tanks and trapped air in wing and fuselage cavities is taken into account, many GA aeroplanes may float for quite a while – some will do so indefinitely.
The trick, now that we have a District Judge’s approval to do so, is to practice the art of landing on water with conventional undercarriage. 
I guess the only buoyancy worth mentioning comes from the air in the wing tanks, if there is any. Fighting hard, but eventually loosing the battle against the weight of the engine and other ton of metal trying to sink down. So, a totally empty fuel tank does not help, but perhaps half empty tanks help. There was an article that mentioned something along the lines that sitting on the tail can help balancing the plane against tipping over with the nose. The engine weighs ca. 1/5 of the entire plane (in my case: 219 kg out 1240, so we need at least that weight behind the wings.
Failure to feather the INOP engine, either due to catastrophic failure of the crankshaft/engine, or poor pilot technique is also a reason why the remaining engine proceeds to take you to the scene of the accident, or ditching in this case.
I wonder if air in the tanks is useful, or if fuel would be better, from a boyancy point of view.
Avgas has a mass 0.72 times that of water. So it is boyant in water. Obviously air would be more boyant. But fuel tanks have vents, and I imagine that woudl let the water in, quickly pushing out the air.
If there is fuel in there, the water is less likely to get in and push the fuel out of the way.
Just some idle mussing
Fighting hard, but eventually loosing the battle against the weight of the engine and other ton of metal trying to sink down
Taking the TB20, empty weight 900kg, tank volume 332 litres i.e. ~330kg.
And most of the 900kg is metal.
No contest.
Even with 100% fresh air in the tanks it will go straight down once the cockpit fills up.
The only planes which will float indefinitely are ones with other cavities which won’t fill up, or ones in which a lot of the empty weight is e.g. wood (a Robin?). But that will be hard to achieve given that the engine and accessories and avionics and have-to-be-metal stuff will come to ~300kg at least.
Peter wrote:
One problem with ditching articles / reports is that those who died (and many have) have not contributed data on what happened.
They did contribute the data that they died.
