and how many singles have boots?
Not many, but I believe Cessna made some SEPs which had them, and maybe one is still in production. And the PA46 has boots. That’s the “mainstream” GA stuff.
Turboprop singles usually have boots too.
almost every guy who comes to look at mine it is stepping up from a single. And you know what they all say? “I have a 210/Bonanza/Mooney/Skylane/whatever, but recently I flew back with my family on a trip at night and I started hearing the engine run a little rough (or sound different). It was pitch black below and we were in IMC…”. That’s all it takes. Every single piston guy that ever hears that will think about a twin real fast. So, this ensures that there will always be some market for them.
That’s in the USA, however, isn’t it? Various factors work against that in Europe… the price of fuel (even in my TB20 that’s the dominant factor), the annual checkride, the old age and poor condition of most twins available for hire (and not many DA42s are available for hire), etc.
So my answer to the initial question: yes, the AVGAS Twins are dead.
That’s what I was getting at, because the DA42 obviously isn’t dead – despite the appearance that most (?) of them were sold to FTOs for ATPL training.
As may happen to aviators in bad weather
Tell me about it. So far we have had the worse May in 40 years, rain, wind and cold. Anyway you don’t need to discuss exact values of MTBF to simply find the effect of a dual redundant system as a twin piston is. A twin has a MTBF of 1.5 times a single. That is all there is to it, almost.
When the (Super) Constellation was still in use, it was nicknamed “the best three engined airliner” by some operators (like Lufthansa) because there were few Atlantic crossings that ended with all four engines running
Maybe this is where the “Luftansa joke” come from. I heard it from my English teacher in the early 80s, but seems to be coming around at regular intervals. For those who have not heard it, read it with a “German” accent.
On a rainy night, Lufthansa flight 645 is leaving Newark enroute to a layover in London, and the pilot’s voice comes over the intercom [in German accented English, of course]: “This is the captain speaking. Hello and welcome to Lufthansa flight 645. We are climbing to an altitude of 30,000 feet and we expect a little turbulence as we pass through the cloud layer. Please remain in your seats with your seatbelts fastened until further notice. And thank you for flying Lufthansa.” This is all perfectly normal, and the passengers sit doing passenger things until the plane hits the first patch of turbulence, and the passengers on the right side of the plane (at any rate those who have not drawn their windowshades — why do people close the windowshades in airplanes at night?) notice — can hardly avoid noticing — a flash, and the whole ship is shaken as something happens out on the wing.
The captain’s voice comes over the intercom [still with the accent, which he has throughout; presumably he is an English-speaking German person, which makes sense if you know what Lufthansa is]: “This is the captain speaking. Hello. Some of you may have noticed that one of the engines has just exploded, and fallen off the plane. We are investigating the cause of that, but rest assured that we will reach London on time as scheduled, as we have still three good engines. And thank you for flying Lufthansa.”
So everything seems fine for ten minutes or so; the plane is not showing any unusual signs of trouble, and it continues ascending towards its cruising altitude, when, bang! The passengers on the left side of the plane (with their shades down) see a flash, and everyone feels the shaking and the captain’s voice comes over the intercom: “This is the captain speaking. Hello. Some of you may have noticed that another one of our engines has just exploded. And it has fallen off the plane. We are also investigating the cause of that. But the co-pilot has just completed his calculations, and we assure that we will reach London about — half an hour behind schedule, and we apologize for the inconvenience, and thank you for flying Lufthansa.”
And everything is fine for a few minutes, and then the captain’s voice comes again over the intercom: “This is the captain speaking. Hello. The co-pilot and I have reached some conclusions in our investigations, and we believe that it would be prudent for those of you who can swim please to make your way to seats on the left-hand side of the plane, and those who cannot swim to make your way to seats on the right-hand side of the plane. We apologize for any inconvenience this may cause you, and thank you for flying Lufthansa.”
This is a strange request, and the passengers look around, but in the end they comply: the swimmers are on the left and the non-swimmers on the right. A few more minutes pass, and everyone in the plane sees a huge flash and feels the plane bucking and diving, and the captain’s voice comes over the intercom: “This is the captain speaking. Hello. Some of you may have noticed that both of our remaining engines have exploded and fallen off the plane. We assure that we will investigate the cause of this. However, we are losing altitude and we will have to crash-land in the North Atlantic. We apologize for any inconvenience this may cause you. When we hit the water, all of those on the left-hand side of the plane, make your way to the exits and then swim like Hell. And all of those on the right-hand side of the plane, thank you for flying Lufthansa.”
A guy I know has a Wing Derringer, which is a neat plane. Two O-320s and pretty good performance. A two seat single with 320 HP would be even faster, but the twin is fun. The Derringer is interesting in that it was designed by John Thorp and has a lot of advanced features for its day – chem milled skins for instance. http://en.m.wikipedia.org/wiki/Wing_Derringer
I think it’s a bit strange to discuss whether some category of aircraft is ‘dead’. I’m not terribly interested in what some imaginary average guy has decided. Planes and people are individuals and some pilots will be flying and owning twins forever, just as some are flying piston engine fighters about 60 years after they were in service, or radial engined biplanes. There’s room for all kinds of planes and less is less, not more. I think it would be fun to have an early C310 in retirement some day, when I’d have time to fiddle with it and take the occasional trip.
PS the training Duchesses etc at my US base must have about a zillion hours on them and fly every day. There are maybe a dozen of them.
… and maybe one is still in production.
AFAIK the TTX (ex Columbia 400) can be ordered with TKS anti-ice. The only one with boots ex-factory was the 210 if I am not mistaken. All others were retrofits.
And AVGAS twins will only be dead when the last drum of AVGAS has dried out 
Right now they are still produced in higher numbers than Diesel twins and there are thousands of them still flying versus hundreds of Diesels. And as long as one can buy a Cessna 340 with good times (six seats, pressurised, de-iced) for 1/4 of a second hand Da42 (4 seats, unpressurised, not deiced…) things will not change radically.
Please, can we stop saying that twins burn twice as much fuel? It’s just not true. They burn at the most 30% more per the equivalent horsepower compared to a single. And for turboprops, the difference is even smaller. You’ll find a lot of TP twins that will burn less fuel, go faster, fly longer than a TP single. Like a Commander 695 compared to a PC12. Beats it on all accounts and burns less. The PC12 burns 73gal/hr doing 270kts, the Commander 60gal/hr doing 300kts.
the mean time between random occurrence failures that will stop both engines in a dual redundant system is only 1.5 times as long as for a single engine.
Yes – but the assumption is that you keep going when one engine fails. In reality you only do that long enough to conclude the flight. If that time is negligible compared to the MTBF, then you really are much better off with two engines.
Suppose that you are making regular two-hour flights in a twin-engined aircraft and that the MTBF each engine is 10 000 hours. Also suppose, for simplicity, that there is no difference in flight time with one or two engines and that there isn’t any suitable diversion site – you have to fly to the destination even in the case of an engine failure.
The double-engine MTBF is then 15 000 hours, but that doesn’t mean that the probability of a double engine failure in any given flight is 2 / 15 000, or once every 7 500 flights.
You will get a single engine failure once in 2 500 flights. Once that happens, you will have on the average one hour to go which gives you a probability of 1/10 000 of a failure of the remaining engine. But after that hour you replace or repair the failed engine. All in all, you will have a complete engine failure once in 25 million flights.
@what next: average SH Cessna 340 price – 250k US. Average DA-42 price – 350k US. The 100k will be gone through very quickly in avgas and maintenance…
They burn at the most 30% more per the equivalent horsepower compared to a single.
To me, the “equivalent horsepower” does not matter a lot. Rather the fuel used for the distance covered. I only have the figures from our flying school that operates – among others – the Pa44 and the Pa28 Arrow whose main difference is the second engine. The arrow cruises at around 110kt on 40l/h, the Seminole does 140kt at 80l/h. Which translates to 50% more fuel burn per NM.
…. and the PA31-350 gives you a knot per litre. :(
The arrow cruises at around 110kt on 40l/h, the Seminole does 140kt at 80l/h. Which translates to 50% more fuel burn per NM.
If you normalize the speed using the typical square law calculation, it comes out 23% more fuel burn for the twin making the same trip at the same speed.
