Future fuel sources

[Ian]

The chance of any airplane engine using it is pretty remote. Roller lifters/tappets were an innovation, coil on plug doesn't exist and basic fuel ecomony measures haven't been implemented. The still rely on rich mixtures to solve cooling problems and can't manage to get fuel mixtures equal across cylinders

[Thruster88]

10 minutes ago, Ian said:

The chance of any airplane engine using it is pretty remote. Roller lifters/tappets were an innovation, coil on plug doesn't exist and basic fuel ecomony measures haven't been implemented. The still rely on rich mixtures to solve cooling problems and can't manage to get fuel mixtures equal across cylinders

Despite the perceived shortcomings of the legacy engines they are quite fuel efficient and they are very reliable and easy to maintain. 

 

Check the chart and see how the IO lycoming compares to late model petrol car engines.

 

https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption

Edited December 5, 2021 by Thruster88

[spacesailor]

I think it will help the ' over temp head ' problem when the fuel detonates,

The ' blurb ' says Cooler without detonation.

Our Jabiru motorneeds a ' antidetination module ' .

spacesailor

[Ian]

15 hours ago, Thruster88 said:

Despite the perceived shortcomings of the legacy engines they are quite fuel efficient and they are very reliable and easy to maintain. 

 

Check the chart and see how the IO lycoming compares to late model petrol car engines.

While the engines are reasonable reliable they do have a number of significant issues and are marginal in many situations. Even skilled operators often operate them in a less than optimal manner which is detrimental to engine life. Because of this people simply cop it on the chin when cylinders, lifters of other components fail short of their expected lifetimes. Virtually no car engines need the babysitting that airplane engines need to operate correctly and modern car engines are simple better across the board. People with zero knowledge often drive them for hundreds of thousands of km.

There's also the chestnut related to load, and how plane engines are designed for high power situations. This record attempt from the 1989 demonstrates the fact that this isn't true, car engines are tested at full power for extended periods.

An example are the issues that Robertson helicopters had which were blamed on low lead fuel. The R22 uses the O360 engine, they had a rash of engine failures however fuel was exonerated. Should failures like this occur on a modern vehicle?

Also the efficiency of the engines relates to the engines running leak of peak not the recommended Rich of Peak settings. As soon as operate in the recommended setting consumption jumps to at least 304g/KWh which puts it on par with Turbine engines. While Lycoming provides advice on how to run LoP they explicitly state. NOTE TEXTRON LYCOMING DOES NOT RECOMMEND OPERATING ON THE LEAN SIDE OF PEAK EGT. (the ALL CAPS is from the Document) So where does that leave you when operating in this manner?

Also large slow revving engines have a significant design advantage for fuel consumption, compared to smaller faster revving engines so they should perform significantly better than car engines.

 

I like mechanical things however these engines should be significantly better than they are. They're simple and a bit shit and have a number of design flaws which have been addressed in modern engines design. 

For example they shouldn't still sell engines with carburetors unless they can demonstrate efficient distribution of fuel. (which they can't) . Instead they like to pretend that the fuel injected engine is a premium thing.

Anti detonation technology has been ubiquitous in car engines for over 30 years but not in aircraft engine, this is despite numerous fatalities relating to engine failures which would have been survivable if the pilot knew the engine was destroying itself.

 

[turboplanner]

1 hour ago, Ian said:

Even skilled operators often operate them in a less than optimal manner which is detrimental to engine life. Because of this people simply cop it on the chin when cylinders, lifters of other components fail short of their expected lifetimes. Virtually no car engines need the babysitting that airplane engines need to operate correctly and modern car engines are simple better across the board. People with zero knowledge often drive them for hundreds of thousands of km.

Aircraft rely on lift to do their work, and the air density is variable. At low levels you can take off first thing in the morning after wiping off frost, do a cross country leg, have lunch, and in 40 degree heat crash into trees at the end of a runway much longer than the one you took off from. There are just two inputs for car engines: rolling resistance, drivelinhe coefficient and surface coefficient. When you're on a bitumen road you can sit back and relax - all the calculations have been done for you, and that's it compared to the pilot that starts beside the sea and flies up to a mountain trip for lunch, crashing into the trees at the end of the runway because the air was less dense. Continuing this, if you want to fly at higher altitudes it's necessary to reduce the richness of fuel, and if you have a constant speed prop you have to make similar decisions to a semi trailer driver with a full load; you have to match the engine load to the condition.

 

That's why we have training for these situations.

With the fuel supply systems and electronics control we have today, it should be possible for the altitude and OAT issues to be factored in by the ECM, but, for example, Cirrus seems to be more prone to mistakes than legacy engines.

 

Quote

There's also the chestnut related to load, and how plane engines are designed for high power situations. This record attempt from the 1989 demonstrates the fact that this isn't true, car engines are tested at full power for extended periods.

I couldn't get the link to work, but that will be something Subaru did probably for publicity.

 

The terms are intermittant loading and constant loading.

 

Aircraft engines are designed for constant loading as ar outboard motors.  Car engines are designed for intermittant loading as are Urban truck engines. Engines of Over the road trucks (long distance) are constant loading.

 

Car engines are cycled on the dyno with varying power demands.

 

Quote

An example are the issues that Robertson helicopters had which were blamed on low lead fuel. The R22 uses the O360 engine, they had a rash of engine failures however fuel was exonerated. Should failures like this occur on a modern vehicle?

Should the O360 be used in a helicopter application where that cold high speed airflow is not available?

Quote

Also the efficiency of the engines relates to the engines running leak of peak not the recommended Rich of Peak settings. As soon as operate in the recommended setting consumption jumps to at least 304g/KWh which puts it on par with Turbine engines. While Lycoming provides advice on how to run LoP they explicitly state. NOTE TEXTRON LYCOMING DOES NOT RECOMMEND OPERATING ON THE LEAN SIDE OF PEAK EGT. (the ALL CAPS is from the Document)

So where does that leave you when operating in this manner?

Self appointed experts come up with bright ideas, push them on people who want to save money and in answer to your questionusually leave the owner paying the bills. If you see something from a manufacturer in relation to using their product it probably means they are very hot under the collar and frustrated.

Quote

Also large slow revving engines have a significant design advantage for fuel consumption, compared to smaller faster revving engines so they should perform significantly better than car engines.

Large slow revving engines being misused?

Fuel consumption relates to two things

1. injector squirts per minute if fuel injected (so rpm)

2. power demand. 

Fuel maps for each engine tell the story of their efficient and inefficient zones, and the manufacturer designe the gearing/prop to work up and down the efficient zone these days.

 

Quote

I like mechanical things however these engines should be significantly better than they are. They're simple and a bit shit and have a number of design flaws which have been addressed in modern engines design. 

For example they shouldn't still sell engines with carburetors unless they can demonstrate efficient distribution of fuel. (which they can't) . Instead they like to pretend that the fuel injected engine is a premium thing.

Anti detonation technology has been ubiquitous in car engines for over 30 years but not in aircraft engine, this is despite numerous fatalities relating to engine failures which would have been survivable if the pilot knew the engine was destroying itself.

I'm sure the aviation industry would welcome new designers who could solve these issues economically.

 

 

Edited December 5, 2021 by turboplanner

[facthunter]

There are actually FEW examples of aero engines destroying themselves because of Detonation. When it has happened it is often a case of fuel contamination with diesel or the pilot stuffing up the cowl gills on a stepped descent etc. Aircooled engines get the advantage of running hotter and getting more efficient but they become more critical to getting it right with higher operating temps. Injection systems have been around for flat motors since the 50's which can be accurately calibrated. They are a bit more tricky to start. People these days are not very engine aware. having a more fit and forget attitude to most things. No matter how you look at it Planes will never run on rails and get there by dynamic relations with air which has many surprises for those who venture there without natural feathers and millions of years to adjust to it. Nev

[Geoff_H]

On 05/12/2021 at 2:04 PM, Ian said:

Just focusing on boil off gas, look at how much higher H2 is compared to it's peers.

The boil off would be fed into an aircraft engine at the appropriate compressor stage!  Low pressure container very doable. 

[Ian]

1 hour ago, Geoff_H said:

The boil off would be fed into an aircraft engine at the appropriate compressor stage!  Low pressure container very doable. 

What about when the plane isn't flying? Or you need to de-fuel after and between flights?

With a low pressure container are you saying that in addition to the 4x volume increase you need a second tank that contains the fuel at something over 10x the volume?

I just don't understand your train of thought. What is the low pressure container and where would it sit.

[Ian]

11 hours ago, facthunter said:

There are actually FEW examples of aero engines destroying themselves because of Detonation.

But probably enough to be concerned. For instance this tragedy may not have eventuated and it concerned the FAA safety team enough to present this. Basically detonation detection is a well understood technology and the patents have all expired. It costs less than an oil change to buy the technology to implement it with off the shelf parts.

11 hours ago, facthunter said:

Injection systems have been around for flat motors since the 50's which can be accurately calibrated.

I know that you can buy aftermarket calibrated injectors however automotive injectors are pre-calibrated or self calibrating and have been since the 1980s. Why can't aircraft engines meet this low bar.

11 hours ago, facthunter said:

They are a bit more tricky to start.

I have had a couple of flat automotive engines which were fuel injected and were never a problem to start. Which means that it's just an engineering issue.

 

11 hours ago, facthunter said:

Planes will never run on rails and get there by dynamic relations

I'm saying that planes should run reliably and be easy to manage to give you time to invest in areas we cant control which are inherently dangerous.

It's easy to pick on plane engines because they are a bit shite. However it is more important is to understand the underlying reasons why this state of affairs exists. A significantly part of the problem is the regulation which while it may have promoted safety in the short term has actually led to a less safe long term outcomes. Basically innovation stalled and the technologies which had been developed in the high end planes disappeared because they became turbine powered. Car engines continued to develop rapidly however these technologies never crossed the ditch, partially because there was a belief that airplane engines were inherently better and those car engineers were cowboys.

Technologies which have enormously benefited automotive engine reliability were actually forced on the industry by emission control laws which aircraft have been exempted from.

 

 

[Ian]

11 hours ago, turboplanner said:

Aircraft rely on lift to do their work, and the air density is variable.

Actually modern turbocharged and some naturally aspirated engines dynamically adjust fuel metering to the delivered air. They also use oxygen sensors to ensure that injectors deliver the right amount of fuel.

11 hours ago, turboplanner said:

Aircraft engines are designed for constant loading as ar outboard motors. 

Actually a number of boat engines are just repurposed automotive engines no real redesign. The reality is that car engines can be run at high loads for extended periods without damage and at optimal levels of efficiency. Aircraft engines can't do this.

 

12 hours ago, turboplanner said:

When you're on a bitumen road you can sit back and relax - all the calculations have been done for you

Actually if you look at modern passenger planes this story is very true. Well designed automated systems actually do a very good job of flying the planes and warn you if you're going to fly into a mountain, pilots actually fall asleep quite a bit . A few meters either side in a car and your goose is cooked. 

12 hours ago, turboplanner said:

If you see something from a manufacturer in relation to using their product it probably means they are very hot under the collar and frustrated.

My point is that the technology exists and has existed for decades which should make this a moot point. It is also cheap as chips to implement. Why are we even asked to manage fuel flow? It is dumb, the manufacturer knows best and yet they give you knobs, inaccurate, uncalibrated fuel delivery and then try to point the finger at others. I think they should be publicly castigated. 

12 hours ago, turboplanner said:

Fuel maps for each engine tell the story of their efficient and inefficient zones, and the manufacturer designe the gearing/prop to work up and down the efficient zone these days.

The problem is the most GA planes don't have these magic fuel maps, don't have calibrated fuel flow and these features only appear in the top end planes.

 

12 hours ago, turboplanner said:

I'm sure the aviation industry would welcome new designers who could solve these issues economically.

The research has been done, the designs are already done. For instance Saab uses a simple mechanism of running current through a spark plug to detect detonation, it's usable on noisy air cooled engines and can detect detonation on a per cylinder basis. Also all the patents have expired. You can just pick up old Saab coils and stick them on a spark plug and they do their thing with a few additional electronic components. The only thing holding this back is the current chip shortage.  

[onetrack]

But how does that Saab detonation detection system perform, in relation to electrical noise issues interfering with aircraft communication devices? 

[turboplanner]

5 hours ago, Ian said:

Actually modern turbocharged and some naturally aspirated engines dynamically adjust fuel metering to the delivered air. They also use oxygen sensors to ensure that injectors deliver the right amount of fuel.

Actually a number of boat engines are just repurposed automotive engines no real redesign. The reality is that car engines can be run at high loads for extended periods without damage and at optimal levels of efficiency. Aircraft engines can't do this.

 

Actually if you look at modern passenger planes this story is very true. Well designed automated systems actually do a very good job of flying the planes and warn you if you're going to fly into a mountain, pilots actually fall asleep quite a bit . A few meters either side in a car and your goose is cooked. 

My point is that the technology exists and has existed for decades which should make this a moot point. It is also cheap as chips to implement. Why are we even asked to manage fuel flow? It is dumb, the manufacturer knows best and yet they give you knobs, inaccurate, uncalibrated fuel delivery and then try to point the finger at others. I think they should be publicly castigated. 

The problem is the most GA planes don't have these magic fuel maps, don't have calibrated fuel flow and these features only appear in the top end planes.

 

The research has been done, the designs are already done. For instance Saab uses a simple mechanism of running current through a spark plug to detect detonation, it's usable on noisy air cooled engines and can detect detonation on a per cylinder basis. Also all the patents have expired. You can just pick up old Saab coils and stick them on a spark plug and they do their thing with a few additional electronic components. The only thing holding this back is the current chip shortage.  

With these answers I wonder then what all the earlier slagging was about?

[Geoff_H]

9 hours ago, Ian said:

What about when the plane isn't flying? Or you need to de-fuel after and between flights?

With a low pressure container are you saying that in addition to the 4x volume increase you need a second tank that contains the fuel at something over 10x the volume?

I just don't understand your train of thought. What is the low pressure container and where would it sit.

For a continuing flight the aircraft could use the boiloff in the APU.  Defuel between longer flights.  I don't see a need for a second tank. Fuel tanks would be in similar places to existing tanks.  But with very good thermal insulation.  I have worked on control systems design of two hydrogen plants, one using methane conversion the other electrolysis, never on liquid hydrogen but have worked on control systems for liquid oxygen/nitrogen plants.  I expect that there would be difficulties but one has to be open to brain storming to advance technology.  

[turboplanner]

9 minutes ago, Geoff_H said:

For a continuing flight the aircraft could use the boiloff in the APU.  Defuel between longer flights.  I don't see a need for a second tank. Fuel tanks would be in similar places to existing tanks.  But with very good thermal insulation.  I have worked on control systems design of two hydrogen plants, one using methane conversion the other electrolysis, never on liquid hydrogen but have worked on control systems for liquid oxygen/nitrogen plants.  I expect that there would be difficulties but one has to be open to brain storming to advance technology.  

Yes, it's here, looking at the basics, that is much more productive than building a one off feature car for a Motor Show that doesn't actually work, but sells everyone on a new fuel or new motive power, like the Jet cars and trucks of the 1950s. The fuel tank, lower power, and infrastructure were the achilles heel of LNG.

[Ian]

7 hours ago, onetrack said:

But how does that Saab detonation detection system perform, in relation to electrical noise issues interfering with aircraft communication devices?

Compared to ignition very well. A small low voltage (compared to ignition) electrical current measures resistance between the plug-gap. The changing resistance over time allows the characterization of a normal ignition events. Pre-ignition and detonation create different resistance profiles and a bob's your uncle.

In terms of interference with electronics it's a very low powered signal compared to ignition.

Also cars now use coil on plug technology which means that you no-longer have the long high voltage leads which tend create electrical noise. The components being smaller and discrete are easier to shield.

[Thruster88]

7 hours ago, Ian said:

Actually modern turbocharged and some naturally aspirated engines dynamically adjust fuel metering to the delivered air. They also use oxygen sensors to ensure that injectors deliver the right amount of fuel.

Actually a number of boat engines are just repurposed automotive engines no real redesign. The reality is that car engines can be run at high loads for extended periods without damage and at optimal levels of efficiency. Aircraft engines can't do this.

 

Actually if you look at modern passenger planes this story is very true. Well designed automated systems actually do a very good job of flying the planes and warn you if you're going to fly into a mountain, pilots actually fall asleep quite a bit . A few meters either side in a car and your goose is cooked. 

My point is that the technology exists and has existed for decades which should make this a moot point. It is also cheap as chips to implement. Why are we even asked to manage fuel flow? It is dumb, the manufacturer knows best and yet they give you knobs, inaccurate, uncalibrated fuel delivery and then try to point the finger at others. I think they should be publicly castigated. 

The problem is the most GA planes don't have these magic fuel maps, don't have calibrated fuel flow and these features only appear in the top end planes.

 

The research has been done, the designs are already done. For instance Saab uses a simple mechanism of running current through a spark plug to detect detonation, it's usable on noisy air cooled engines and can detect detonation on a per cylinder basis. Also all the patents have expired. You can just pick up old Saab coils and stick them on a spark plug and they do their thing with a few additional electronic components. The only thing holding this back is the current chip shortage.  

So are you going to pull the lycomings from the Defiant and replace with something like this https://www.vikingaircraftengines.com/viking-150-engine 

They have every feature you desire.  

[Ian]

2 hours ago, turboplanner said:

With these answers I wonder then what all the earlier slagging was about?

The issue is that the technologies aren't mainstream in GA whereas it has in the automotive and RPT industry and RPT. And they are really inexpensive.

[Ian]

27 minutes ago, Geoff_H said:

For a continuing flight the aircraft could use the boiloff in the APU.  Defuel between longer flights.  I don't see a need for a second tank. Fuel tanks would be in similar places to existing tanks.  But with very good thermal insulation.  I have worked on control systems design of two hydrogen plants, one using methane conversion the other electrolysis, never on liquid hydrogen but have worked on control systems for liquid oxygen/nitrogen plants.  I expect that there would be difficulties but one has to be open to brain storming to advance technology.  

The thing that hydrogen has going for it is its weight for energy content however the volume issues are huge.

I'd like the concept to work however the plane that I fly carries about 400L of fuel which gives a range of about 2000km. If I convert this to hydrogen I need at least 4x of this storage 1600L, plus a containment vessel which needs to be spherical/cylindrical so it the wings are no longer a good fit. So essentially airplanes need to look like Belugas (Which is doable if you accept the extra resistance)

Then there's the whole logistics thing.

At a fundamental level this is why people are looking at ammonia to transport hydrogen, but ammonia is a dangerous gas. It's poisonous and explosive, its only good quality is that you can smell a leak.

 

[turboplanner]

34 minutes ago, Ian said:

The issue is that the technologies aren't mainstream in GA whereas it has in the automotive and RPT industry and RPT. And they are really inexpensive.

I attempted to explain some of the constraints to your theory, you can't just take a water cooled car engine and put it in an aircraft; but it's a lot more complicated, and on top of that there are financial pressures which are working against low volume applications like GA and RA sports use.

[Ian]

23 minutes ago, Thruster88 said:

So are you going to pull the lycomings from the Defiant and replace with something like this https://www.vikingaircraftengines.com/viking-150-engine 

They have every feature you desire.

I think Jan the owner has a more of a history in marketing than engineering. He was behind the Subaru conversions which had a very high failure rate and didn't appear to understand basic engineering principles. Based upon previous history I'd put a big question mark over the the reduction gearbox design. It's difficult nut to crack and he doesn't appear to use engineers and has no budget for R&D. 

But seriously ideally I'd like an engine that could run on Jetfuel, diesel or biodiesel, it's safer and it availability is better than avgas. I also expect that the supply will remain available for longer periods as people will continue want to fly overseas and not have to take a boat. 

 

[Ian]

19 minutes ago, turboplanner said:

I attempted to explain some of the constraints to your theory, you can't just take a water cooled car engine and put it in an aircraft; but it's a lot more complicated, and on top of that there are financial pressures which are working against low volume applications like GA and RA sports use.

I don't think that I mentioned putting water cooling or putting car engines in planes. What I did mention was that the engines which operate our planes are susceptible to modes of failure which modern engines aren't. Some of the remediation costs from a design perspective are very low and yet they haven't occurred.

The profit margins on 0360 engines was quite high, this created the clone market which resulted in some reduction of the prices and actually created some innovation which wouldn't have happened otherwise. Look at roller lifters, introduced first by the clone engine makers and finally Lycoming started to do it. It sounds odd, how could lower margins drive innovation and yet it did.

Unfortunately some of the clone supplier have been bought by the companies whose margins they threatened.

[Geoff_H]

The one car engine that was rebuilt as an aircraft engine was the Porsche. One control " how much power do you want".  Mooney fitted them to new aircraft as an option.  However as it needed two alternators for electronic reliability and a gearbox it was heavier than a Lycoming of same HP. The Porsche model was slower than the Lycoming model.  Who buys a slower Mooney... not many people.  So upon its failure to sell any great numbers Porsche refitted most aircraft with Lycoming engines.  I had an unconfirmed report that only 5 Mooney Porsche still exist.  I had the pleasure of flying one over the top of Melbourne.  Sheer delight.  Very quiet.  A great product failed by marketing problems.  I feel that we are in for a similar situation with having to go "green".

[Geoff_H]

"plus a containment vessel which needs to be spherical/cylindrical so it the wings are no longer a good fit."

 

not at all if the tank pressure is atmospheric and the hydrogen is at saturation temperature!  But the smaller the surface area the less insulation needed.

[Geoff_H]

Liquid fuel would be delivered to the engine (gas turbine jet) and demand and evaporation done in a similar way to spacecraft engines that use hydrogen/oxygen fuel.

[facthunter]

Those high tech engines have promised but not delivered.

  The Simple clunkers, Regardless of how you want to deride them and anyone who says they are the best available. they ARE the best available. I hate ALL piston engines if I'm thinking straight.. They are probably 20 times more likely to fail than a bypass jet.. A normal car and a race car engine are and a truck engine are built for purpose. You don't swap one for another. An aircraft engine is very specialised even if YOU don't think so. Probably the Lycoming 0-360 is about the most reliable motor and that's often in the hands of an unenlightened operator. and in many  different aircraft.. Nev