Passengers will never accept diesels. They struggle with Turboprops.
Passengers won't perceive a difference. To non pilot passengers, a propeller driven plane is a propeller driven plane, most of them don't even know there's a turbine in there - they just see it has propellers. In fact I'd go so far to say most passengers don't even care much about that, all they care about is the lowest fare - if they didn't, Ryanair wouldn't be as successful as it is.
I'll second that. Your average passenger doesn't know the difference between a turboprop and a piston-engined aeroplane. To the punter, a Dash 8 is just a bigger version of an Islander.
Do they look and say "oh, it has propellors, how quaint!" ? Yes.
Do they refuse to board? No. The fare is the only thing that really matters to them.
I thought one of the main advantages of turbojets (with ducted fans) were that they were effective up to about Mach 0.8, while unducted propellors, regardless of whether they are driven by a turbine engine (turboprop) or a piston engine, were only effective up to about Mach 0.6. Above these numbers the propellor/fan tips approach the transonic regime, become less effective and very noisy.
On a transatlantic crossing, the difference between mach 0.8 and mach 0.6 is multiple hours. Which will be another important factor for passengers.
Now I think theoretically it would be possible to have a piston diesel engine driving a ducted fan instead of an unducted propellor, but I doubt it will be pretty.
Passengers will never accept diesels. They struggle with Turboprops.
Depends on the cathegory of airplane. I think however that many have in the mean time stopped thinking about it after props became more common again on commuter planes. I do remember vividly a discussion I had with a pax (as pax myself) in a Saab 2000 in the late 90ties who seemed to think that the airplane was a DC3 kind of plane... when I told him that the aircraft was brand new (had about 3 months on it) and featured a totally electronic cockpit visually not unlike the A320 and more advanced than the CRJ he'd been flying to ZRH but was much more economical (Using about 30% or even less fuel on our trip than the CRJ does with the same number of pax while "loosing" 5 minutes in slower flight time, she quickly reconsidered.
I agree that most pax won't even know about turboprops, for most of them however props are now quite normal.
And Diesel engines vs Avgas planes:
Passengers go for looks, big time. And a DA42 looks a lot newer and "sexier" than say a Seneca or Twin Commanche to the uneducated pax, likewise a DA40, Cirrus or Columbia vs a Mooney or Arrow. And after they've sat in a G1000 or Avidyne cockpit many will snort if confronted with a steam gauge plane. That is what they'll consider, not what is under the cowling.
The AOPA Article very much confirms what my sentiments have been all along. Continental seems to think along the same lines. It appears to me that we shall see rapid developments of STC's for a wide range of GA airplanes now that Conti is behind both Thielert and SMA. Which is good. I'll be looking out very attentively on this issue.
I expect the market to go for diesel in a big way once the major stumbling blocks are out of the way (affordable STC's and engines, higher maintenance intervals) and once people realize what a diesel engine can do for them that Avgas can't. The lower end will go towards Mogas and Rotax (100-125 hp), Diesel and Continental for the mid range and turboprops for higher ranges. The industry has been waiting for some major developer taking over those engines and guaranteeing both reliability and availability rather than some "exotic" outfits with rather instable history. And many who have flown behind a Diesel engine know and appreciate the ease of operation as well as the much lower cash drain at the gas station :) And of course the effect that they get fuel almost everywhere, in Europe anyway.
this dicussion picks up from here
I believe that when proper 300-350bhp diesel/jetfuel engines come to the market you will see that a 200kts tourer will make a lot of sense.
I cannot wait to put such an engine on my Commander. Currently It flies around 160kts at 16-17gph rich or 13.5 lean. The problem is always cyl nr 5 that gets to hot. Yesterday I started with a headwind of about 45-50kts.. At the end near Geneva it was 10kts..
With such a dieselengine it means that I would fly ias 165 at fl100 meaning 195-200 kts true burning max 12gph..
SR22, TB20, Commanders and the likes will profit and will become very attractive.
@Commander wrote:
I believe that when proper 300-350bhp diesel/jet fuel engines come to the market you will see that a 200kts tourer will make a lot of sense.
Don’t hold your breath …
I followed closely the whole SMA turbo-diesel development, which seems to be completely dead as of late.
You see, there are very good reasons why turbo-diesels have not and probably will not take over the entire GA fleet.
The main drawbacks with diesel :
- Serious vibration that literally destroys props;
- Huge cooling requirements that end up taking a big toll on performance due to the added cooling drag ;
- Weight increase due to prop dampening, cooling system and the higher density of “heavy” fuels.
Besides, what’s wrong with the 300 hp Contis & Lycos that power just about every single 4 – 6 seat touring machine out there ?
BTW, the Commander 15TC model should do a proper 180 TAS in the low FLs right now …
Commander wrote:
I believe that when proper 300-350bhp diesel/jetfuel engines come to the market you will see that a 200kts tourer will make a lot of sense.I cannot wait to put such an engine on my Commander. Currently It flies around 160kts at 16-17gph rich or 13.5 lean. The problem is always cyl nr 5 that gets to hot. Yesterday I started with a headwind of about 45-50kts.. At the end near Geneva it was 10kts..
With such a dieselengine it means that I would fly ias 165 at fl100 meaning 195-200 kts true burning max 12gph..
SR22, TB20, Commanders and the likes will profit and will become very attractive.
Does anyone here know more about SMA and their progress on its 6-cylinder engine SR460? http://www.smaengines.com/our-product/sr460
They(SMA and Cessna) were supposed to put the small one in the new factory-built Cessna 182 but it has not been released to the costumers yet(AFAIK). It has been delayed and it must be due to the new engine setup since I guess that the rest is same ol’.
Michael wrote:
I followed closely the whole SMA turbo-diesel development, which seems to be completely dead as of late.
Seems as I started writing before you posted this. Thanks for the info.
The most promising is the Mercedes based CD-300 V6 turbodiesel with 300+ hp that has already flown in the SR22
Michael wrote:
Serious vibration that literally destroys props;
I’ve never heard about this before. Could you explain?
Huge cooling requirements that end up taking a big toll on performance due to the added cooling drag ;
Why is that? Do diesel engines have lower thermal efficiency compared to petrol engines? If not, where does the additional heat come from?
Weight increase due to prop dampening, cooling system and the higher density of “heavy” fuels.
How is the fuel density important? The fuel mass should be what matters and since jet/diesel fuel has (slightly) higher energy density than petrol, you can get the same amount of energy for less weight with jet/diesel fuel (assuming the same thermal efficiency of the engine).
