Diesel Debate
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Joined: Sep 2003
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From: NW England
Diesel Debate
Chewing the fat on Sunday afternoon I was discussing the diesel concept with the Owner of a flying school and a couple of PPL's and the Flying School Owner came up with a very valid point.
PPL John Do flying his newly aquired disel aircraft is at the pumps filling up with Jet A1 and is paying no duty for his personal flying fun. Mr Flying School Owner is mighty pissed off that he is paying £5 a gallon and trying to run a business.
Theory being that the no duty on Jet A1 will last about as long as it takes the flying schools or other whingers to kick up enough fuss that the government realise the loophole and promptly shut it by making Jet A1 / diesel more expensive than Avgas / petrol.
If you think it won't happen, look how cheap motor vehicle diesel once was to the price today.
Anyway, once the tax loophole closes, what will be the benefit of all this diesel technology??
Seems a shame to me, that good positve research and development could be stopped dead in its tracks at the whim of a government.
PPL John Do flying his newly aquired disel aircraft is at the pumps filling up with Jet A1 and is paying no duty for his personal flying fun. Mr Flying School Owner is mighty pissed off that he is paying £5 a gallon and trying to run a business.
Theory being that the no duty on Jet A1 will last about as long as it takes the flying schools or other whingers to kick up enough fuss that the government realise the loophole and promptly shut it by making Jet A1 / diesel more expensive than Avgas / petrol.
If you think it won't happen, look how cheap motor vehicle diesel once was to the price today.
Anyway, once the tax loophole closes, what will be the benefit of all this diesel technology??
Seems a shame to me, that good positve research and development could be stopped dead in its tracks at the whim of a government.
Why do it if it's not fun?
Joined: Jul 2001
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From: Bournemouth
Anyway, once the tax loophole closes, what will be the benefit of all this diesel technology??
FFF
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This may need correcting: The new diesel engines consume considerably less fuel, so even if the price/ltr were the same, the costs would be significantly less.
EDIT: Hehe, posted the same time as FFF. Also, I think the fact that the new breed of water cooled engines don't use fuel as a coolant goes someway to helping the fuel economy!!
EDIT: Hehe, posted the same time as FFF. Also, I think the fact that the new breed of water cooled engines don't use fuel as a coolant goes someway to helping the fuel economy!!
Joined: Jan 2004
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From: Nottingham UK
The argument for diesels in new aircraft seems unarguable, although has anyone any experience of their reliability? One item they can't function without is the fuel pump, I don't even have one on my crate, and I don't believe either the SMA or the Thielert has a backup in case of failure.
On the subject of the end of 100LL and the vast bulk of aircraft currently dependent on it, there are other options. I find it hard to justify the cost of the SMA conversion, E95k plus Vat, I believe. The Thielert is around half that I think, but it's also got half the power. I'd be interested to hear from anyone who's taken the plunge. into diesel, but also interested to hear if anyone's taken the trouble to convert to unleaded avgas (not mogas), which is currently available in Scandinavia, and maybe elsewhere.
On the subject of the end of 100LL and the vast bulk of aircraft currently dependent on it, there are other options. I find it hard to justify the cost of the SMA conversion, E95k plus Vat, I believe. The Thielert is around half that I think, but it's also got half the power. I'd be interested to hear from anyone who's taken the plunge. into diesel, but also interested to hear if anyone's taken the trouble to convert to unleaded avgas (not mogas), which is currently available in Scandinavia, and maybe elsewhere.
Joined: Mar 2003
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From: SE England
Hypothetically, if you had to identical aeroplanes i.e 2 Cessna 152's but one diesel and one AVGAS, how would they compare performance wise? I know if you look at some cars, diesel gives them a lesser acceleration rate for example. Is diesel also not going to harm the envionment?
Joined: Mar 2000
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From: U.K.
What, in comparison to the oh-so green environmentally friendly engines we have at the moment?
A modern Diesel will be far less damaging than the current rubbish we have fitted to our a/c.
The power characteristics of a diesel suit an a/c far more than they do a car. We don't need lots of revs unlike your average hot hatch.
Overclock, why should a Diesel be any less reliable than a petrol engine? One of the reason lycomings etc. need redundancies is because they go wrong all the time!
The modern engines should be more reliable, but should still have as much redundancy as an 'old' one.
I know what I'd prefer up front if I was to cross shark infested waters in a single!
A modern Diesel will be far less damaging than the current rubbish we have fitted to our a/c.
The power characteristics of a diesel suit an a/c far more than they do a car. We don't need lots of revs unlike your average hot hatch.
Overclock, why should a Diesel be any less reliable than a petrol engine? One of the reason lycomings etc. need redundancies is because they go wrong all the time!
The modern engines should be more reliable, but should still have as much redundancy as an 'old' one.
I know what I'd prefer up front if I was to cross shark infested waters in a single!
Joined: Jun 2003
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From: EuroGA.org
Equalising fuel tax would remove most of the financial incentive to go for a diesel. One already needs upwards of 500hrs/year to make the case.
Fortunately turbine fuel is tax-free by international treaty and putting tax on it would not be a trivially simple move. The definition of a domestic v. international flight would be interesting. But it could be done. Whether they would bother is another matter; I recently read (so it must be true) that the UK avgas usage is 0.3% of the UK avtur usage.
Lycoming and/or Continental have developed FADEC for their petrol engines, for the US market where avgas is cheap. But this won't produce MPG savings over an identical non-FADEC engine operated LOP. It should eliminate one or two levers though.
Fortunately turbine fuel is tax-free by international treaty and putting tax on it would not be a trivially simple move. The definition of a domestic v. international flight would be interesting. But it could be done. Whether they would bother is another matter; I recently read (so it must be true) that the UK avgas usage is 0.3% of the UK avtur usage.
Lycoming and/or Continental have developed FADEC for their petrol engines, for the US market where avgas is cheap. But this won't produce MPG savings over an identical non-FADEC engine operated LOP. It should eliminate one or two levers though.
Joined: Jul 2002
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From: Sunny side up pls..
Diesel
Guess about 2 years ago "Flying" had an article on a converted
Pa28 Warrior.
Same HP as on avgas but twice the endurance they claimed ten(!)hrs on 5 gallons/hr.
Down side is first conversion is expensive due to the different engine mounts you need.
After that is evenly priced with a similar Hp Lycoming.
So we're just waiting for the first one to fork over 30 grand.
Even for a good running flightschool it takes some time to get that investment back.
And there was something about a vibration dampener that had to be replaced every 1000hrs.
Pa28 Warrior.
Same HP as on avgas but twice the endurance they claimed ten(!)hrs on 5 gallons/hr.
Down side is first conversion is expensive due to the different engine mounts you need.
After that is evenly priced with a similar Hp Lycoming.
So we're just waiting for the first one to fork over 30 grand.
Even for a good running flightschool it takes some time to get that investment back.
And there was something about a vibration dampener that had to be replaced every 1000hrs.
Joined: May 2001
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From: Escrick York england
some thing to consider
i was at the enstrom helicopter factory asking the ceo if he ever thought he would put a desiel engine in one of his helis he asked why would you ,i told him of the price of avgas to jet ai he replied to me that in the us avgas costs the same as jet ai so there would not be a market for a heavier engine with less power
steve
i was at the enstrom helicopter factory asking the ceo if he ever thought he would put a desiel engine in one of his helis he asked why would you ,i told him of the price of avgas to jet ai he replied to me that in the us avgas costs the same as jet ai so there would not be a market for a heavier engine with less power
steve
Joined: Mar 2000
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From: U.K.
That shows that Enstrom don't give two hoots about the rest of the world.
It isn't feasible to put a diesel lump in a heli at the moment due to the weight, but why bother whan you can have a turbine anyway? (yes more expensive, but I know what I prefer, but as I don't pay for it...)
A fixed wing a/c isn't quite as weght sensitive as light Heli, but the fact that you can get much better fuel economy should mean you could take less juice for the same sortie, a good weight saving there.
Avgas engines will eventually go the way of the dinosaurs, they will either be destroyed by the competition or legislated out of existance. I just hope we don't get into a similar near monoploy situation that we have been in when diesels become the only power plants available. What could the prices be if that were to happen?
It isn't feasible to put a diesel lump in a heli at the moment due to the weight, but why bother whan you can have a turbine anyway? (yes more expensive, but I know what I prefer, but as I don't pay for it...)
A fixed wing a/c isn't quite as weght sensitive as light Heli, but the fact that you can get much better fuel economy should mean you could take less juice for the same sortie, a good weight saving there.
Avgas engines will eventually go the way of the dinosaurs, they will either be destroyed by the competition or legislated out of existance. I just hope we don't get into a similar near monoploy situation that we have been in when diesels become the only power plants available. What could the prices be if that were to happen?
Joined: Mar 2003
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From: SE England
Evo, i think you ar correct about GWC flyinig school and diesel conversions. I know they were playing around with 'the' diesel cessna there for a day with all its advertising on it blah blah. There were quite a few people staring open mouthed and wide eyed at it 
Joined: Jul 2003
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From: Minnesota
Just a thought about the redundancy issues of petrol aero engines vs. diesel aero engines.
The current regulations call for dual ignition systems in petrol engines, 2 magnetos, 2 sets of plug wires and 2 spark plugs per cylinder, not the norm in petrol engines, but retrofit able at reasonable cost. With diesel engines, the duality of injection pumps, lines and injectors are probably only possible at considerable expense.
In my experience, modern diesel engines, especially small diesel engines are no more reliable, and have no greater lifecycle (given the same duty cycle) than modern petrol engines. So there may be a safety, or reliability issue to address.
Yes, diesels are about 10% more fuel efficient, but diesel fuel is heavier than petrol, so the volume of 'fuel' is less, but the weight more or less the same. Remember in terms of equivalency the diesel engine would need to be larger than a petrol engine to produce the same power.
Now I may be completly wrong here but, Jet A may not have the same calorific value as DERV, so the expected increase in fuel efficiency may not be attainable.
I am not against diesel engines in aircraft, I just think we need to look very closely before we commit.
W.B.
The current regulations call for dual ignition systems in petrol engines, 2 magnetos, 2 sets of plug wires and 2 spark plugs per cylinder, not the norm in petrol engines, but retrofit able at reasonable cost. With diesel engines, the duality of injection pumps, lines and injectors are probably only possible at considerable expense.
In my experience, modern diesel engines, especially small diesel engines are no more reliable, and have no greater lifecycle (given the same duty cycle) than modern petrol engines. So there may be a safety, or reliability issue to address.
Yes, diesels are about 10% more fuel efficient, but diesel fuel is heavier than petrol, so the volume of 'fuel' is less, but the weight more or less the same. Remember in terms of equivalency the diesel engine would need to be larger than a petrol engine to produce the same power.
Now I may be completly wrong here but, Jet A may not have the same calorific value as DERV, so the expected increase in fuel efficiency may not be attainable.
I am not against diesel engines in aircraft, I just think we need to look very closely before we commit.
W.B.
Joined: Mar 2000
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From: U.K.
The problem is WB, that we are all grasping for the new engines because of the old tat we put up with at the moment.
You comments about Diesel engines being no more reliable than a MODERN petrol engine maybe true, but the engines we have at the moment cannot be described as modern in any sense of the word.
My club has been on the recieving end of two serious engine problems in the last month, both on supposedly 'first life' engines. One total failure where a pot parted company with the rest of the engine and a badly holed piston. Both a/c are under 3 years old and have been looked after and yet they don't reach their TBO!
Why have we put up with such cr*p for so long? Bring on something reliable.
You comments about Diesel engines being no more reliable than a MODERN petrol engine maybe true, but the engines we have at the moment cannot be described as modern in any sense of the word.
My club has been on the recieving end of two serious engine problems in the last month, both on supposedly 'first life' engines. One total failure where a pot parted company with the rest of the engine and a badly holed piston. Both a/c are under 3 years old and have been looked after and yet they don't reach their TBO!
Why have we put up with such cr*p for so long? Bring on something reliable.
Joined: Feb 2002
Posts: 577
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From: Inverness-shire
Just a passing thought on the redundancy issue
Daimler Benz used to make some rather fine fuel injected avgas powered aero engines - re the DB 605 etc etc
They put in two sets of magnetos and spark plugs but only one injector pump
It tends to imply that mags and more especially spark plugs were far more likely to fail than an injector pump, even back then.
And how many accidents reported each month are blamed on carb icing?
Having driven a diesel car for 170 000 miles without laying a finger on the engine (oil and cam belt changes excepted), I would go for a diesel aircraft any day of the week - if they were available at anyhting like a reasonable cost
Daimler Benz used to make some rather fine fuel injected avgas powered aero engines - re the DB 605 etc etc
They put in two sets of magnetos and spark plugs but only one injector pump
It tends to imply that mags and more especially spark plugs were far more likely to fail than an injector pump, even back then.
And how many accidents reported each month are blamed on carb icing?
Having driven a diesel car for 170 000 miles without laying a finger on the engine (oil and cam belt changes excepted), I would go for a diesel aircraft any day of the week - if they were available at anyhting like a reasonable cost
Why do it if it's not fun?
Joined: Jul 2001
Posts: 4,782
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From: Bournemouth
W.B.
Nothing wrong with the healthy scepticism you've expressed
However, there are a couple of points which I'm sure you've got correct:
You say that modern diesel engines have no greater lifecycle than modern petrol engines. I'm not sure that's true. Diesels tend to be employed in high-usage situations - taxis, lorries, vans and so on. Many of these are driven for hour after hour, day after day, and survive for many many years. Petrol engines aren't generally put to this kind of extreme use, but if they were, I'm not sure how many would survive?
As for duality, I think this comes down to the reliability of the individual system. Aeroplane engines aren't required to have two camshafts, because camshafts don't generally fail. They are required to have dual ignition systems, because ignition systems do fail. Just ask any AA patrol man - if they are called out to a car with a petrol engine which doesn't run, then assuming that it's not a battery problem (i.e. the engine turns over when the starter motor is used) and the fuel tank is not empty, the ignition will always be the first thing they will look at. That's the reason why we have two of them in our aircraft.
Just some thoughts to stir things up a bit!
FFF
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Nothing wrong with the healthy scepticism you've expressed
However, there are a couple of points which I'm sure you've got correct:You say that modern diesel engines have no greater lifecycle than modern petrol engines. I'm not sure that's true. Diesels tend to be employed in high-usage situations - taxis, lorries, vans and so on. Many of these are driven for hour after hour, day after day, and survive for many many years. Petrol engines aren't generally put to this kind of extreme use, but if they were, I'm not sure how many would survive?
As for duality, I think this comes down to the reliability of the individual system. Aeroplane engines aren't required to have two camshafts, because camshafts don't generally fail. They are required to have dual ignition systems, because ignition systems do fail. Just ask any AA patrol man - if they are called out to a car with a petrol engine which doesn't run, then assuming that it's not a battery problem (i.e. the engine turns over when the starter motor is used) and the fuel tank is not empty, the ignition will always be the first thing they will look at. That's the reason why we have two of them in our aircraft.
Just some thoughts to stir things up a bit!
FFF
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From: EuroGA.org
I have been told by several engine shops that quality control at Lycoming is atrocious nowadays.
The crankshaft issue (defective heat treatment and other stuff) is just the tip of the iceberg. The most concerning thing is that while Lycoming say that engines not on their "dodgy" serial number list are not affected by the SB, they did recall every -540 engine with an aftermarket turbo fitted even if the waste gate is set to that the rated HP is the same.
The crankshaft issue (defective heat treatment and other stuff) is just the tip of the iceberg. The most concerning thing is that while Lycoming say that engines not on their "dodgy" serial number list are not affected by the SB, they did recall every -540 engine with an aftermarket turbo fitted even if the waste gate is set to that the rated HP is the same.
Joined: May 2001
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From: 75N 16E
Hmm....a modern, digitally controlled Jet A1 powered aircraft, or a 30 year old, 5 litre air cooled lump (capable of shock cooling)bolted to a manually operated VP prop.....
I don't think reliability is going to be an issue compared to Avgas engines, I'd certainly be willing to try them.
EA
I don't think reliability is going to be an issue compared to Avgas engines, I'd certainly be willing to try them.
EA