In fact, I can make a very good statistical case for the fact that Avgas singles are actually dying. The decline in sales in singles is percentually much higher than the decline in sales of twins.
Quoted: SE Piston fell from a high of over 2,500 deliveries in 2007 to only 986 in 2014, a 60% decline. Business jets fell from a high of over 1,300 deliveries in 2008 to only 722 in 2014, a 45% decline. ME piston aircraft fell from 258 in 2007 to 143 in 2014, a 45% decline—not great, but not as bad as SE piston aircraft.
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Adam: somewhere in the beginning of your posting, the “avgas” notion quietly disappeared…
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.
Yes, I see what you mean, and maybe I start to understand this too eventually. What you are talking about is the rate of failure. The rate is defined as the density probability divided by (1 – the probability). This is the mother of all counter intuitive things for a redundant system. The rate increases with time. For a single system (SEP or SET) the rate is always constant. The rate for a redundant system is not (which is why the MTBF is so small). Each time you fly a SEP the rate of engine failure is exactly the same, considering random occurrence. Each time you fly a MEP, the rate of engine failure increases. This is just the effect of the density distribution.
I have plotted the rate below using 3500 and 350k
… it comes out 23% more fuel burn for the twin making the same trip at the same speed.
I guess this is about correct, but probably no one tried it yet in real life. If you have an aircraft that happily cruises at 140kt on 60% power, you will not slow down to 110kt to “compete” with a slower aircraft in terms of fuel burn. This would be like an A320 flying at M0.5 to prove that it only burns 20% more fuel than a DHC 8…
The arrow cruises at around 110kt on 40l/h.
Is the gear retraction mechanism broken? The Arrow should be doing ~135kts TAS on around 9 USG/h (cruising at around FL070) (also assuming an NA Arrow).
Is the gear retraction mechanism broken? The Arrow should be doing ~135kts TAS
I was wondering about that too. But on the other hand the Hershey bar wing Arrow (PA28R-180) is slower than the -201
Each time you fly a SEP the rate of engine failure is exactly the same, considering random occurrence. Each time you fly a MEP, the rate of engine failure increases.
I can’t see how this can happen unless you keep flying with only the remaining engine after the first one fails. And as I said, in practise you don’t do that more than needed to get the aircraft safely on ground.
It would be a completely different matter if you can’t abort the mission and also can’t repair or replace the failed unit – e.g. on an unmanned spacecraft.
I think there are several factors why twins have lost a lot of followership.
The first and foremost is cost. Two engines to overhaul, two props and yes, 30% more consumption than a comparable single is a huge factor too.
In Europe, many Twins have MTOW of more than 2 tons, which means airway charges. People avoid those like the plague so they downgrade them to 1999 kgs, which means they can´t get more than 2 people inside. Kind of useless that way.
And then come the rules which make Twins unattractive for operating into small airfields re runway requirement.
Also, Boscomantico is very right: Cirrus and their shute have gotten many to reconsider the “safety” aspect of the twin engines. If you can have an “out” in darkness or IMC when the single engine quits, why not go single.
For myself, it is pure cost. I would be on a twin tomorrow if I had the money, most probably I´d go for a Turbo Twin Commanche. I looked at several, talked to owners and had to tell myself that I can not justify or stemm the costs.
On the other hand, if I had the money to buy a 250-300k SEP, my choice would be abundantly clear: Spend 50-80k on a good twin and use the rest of the money to fly it. A nice Turbo Twin Commanche, Seneca II or the likes can be easily found for that money and flown. And 150-200k € will buy a lot of upgrades, fuel and even engine overhauls.
As for the market itself, I have to agree with the poster who said it is practically dead.
We can not really talk of a “market” if we see quantities like we have for years. We can not really talk of a market when even good and proper second hand planes sell way under their estimate prices, when buyers will walk away for almost any ever so small deficiency and expect a “new” plane for 10k € and when the majority of “interested” people are just dreamers who have not even had the guts to tell their wifes.
Add to that sellers who do not know or care about how to advertize and are blissfully unaware of the market conditions. Or are justifyably disgusted with people who call them up and offer ridiculous amounts on sound airframes just because they know there are basically no buyers. Yes, that is the free market but it is still not a good thing that it happens this way. And of course you will have desparate sellers who will basically give away their airplanes just to be rid of them.
Also, a lot of “budget” planes on platforms like planecheck which in fact are nothing but projects, unflyable hulks which probably will never fly again, litter the market and hide the real bargains.
Add to that a certain amount of uncertainty of what our regulators will come up next which will render sound IFR airframes subject to 20-30k upgrades at the touch of one pen.
And then there is one other factor which greatly influences people who want to buy: Forums.
I have recently seen several discussions in various forums which will dissuade just about anyone from airplane ownership. The scheme is the same always:
- Someone who has finally taken the step of actively looking posts some ads for people to comment on.
What he gets is : “Are you crazy to even look at this piece of shit.” Followed by horror stories of ownership, how expensive everything is, how impossible it is to even do minor avionic upgrades where necessary e.t.c. A lot of what is said is true but is the cumulation of the sum of all frustrations and fears of present and past owners.
Yes, you do get educated opinions, but also for them it is difficult as hell to judge so they will be cautious. Yet, the sum of it in most cases is :Stay the HELL away from ownership.
So most of those who ask run away and stay away for good.
I have had several of such people contacting me per mail and often personally about ownership and the first few HOURS were usually spent with dispersing totally false and exagarated balderdash they have heard or seen at the forums or at the local airfield.
We have to ask ourselfs whether that is really what we want to do. Yes, we all have had our frustrations, not few of them. They are part of airplane ownership but mostly they are NOT what ownership is all about. Or maybe I am naive and it is and that is why the market is dying.
That is the European market.
The American market from where I am sitting is different in the sense that people are much more of a “can do” attitude, yet there are a lot more “dogs” out there in the hangars as oversight and technical control appears to be much less. So landing a scrap heap in a bargain buy is more likely than in Europe.
Sorry for ranting on but that is how I see the conditions here. It is difficult to sell or promote SEP´s let alone Twins. Even though a real bargain twin, of which there are many, can still do a great service and fly on a much smaller budget than a new 1 million SEP.
From prices actually paid, which are almost never posted publicly but I hear an awful lot of them privately, there seem to mainly be two markets for used aircraft: those which fetch “nothing” or get massively knocked down (e.g. a 60k-advert price knocked down to 30k) to achieve a sale, and those where people pay a surprisingly high price.
It’s possible that the first market is mostly non-savvy buyers who buy into the “stories”, and the second market is savvy buyers who know what they want, have a realistic budget, do a competent prebuy, are able to do a flight test and check everything works, and don’t waste time.
The problem is that not many buyers are savvy. Most cannot (for example) check if the autopilot works in its various modes. Most engineers that travel to do prebuy checks can’t do this either; it’s a rather specialist task.
Non-savvy buyers depress the price in any market… the avionics shops (for example) dislike them because these people get 5 quotes for installing a transponder….
It could also be that the 30+ year old planes (which are the majority of the GA population) just get ritually knocked down – because it is hard to make them look nice. Certainly the cases I have seen where surprisingly high prices were paid were all under 15 years of age.
Is the gear retraction mechanism broken? The Arrow should be doing ~135kts TAS on around 9 USG/h (cruising at around FL070) (also assuming an NA Arrow).
According to the book, the Seminole should be doing 165KT instead of the 140 we use to see in ours… I have no idea why our Arrow is so slow. Whenever ATC asks for “high speed as long as practical” on the ILS, all we can get with the gear up and a lot of power is 140KT.
