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math341c
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Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 09, 2021 4:52 pm

Hello guys, my Name is Math and I am a student pilot, some weeks ago I started my first IFR flight lessons, where I flew for the first time the Diamond DA-40 TDI, which runs on Jet-A fuel, however the aircraft I flew my VFR hours on, was a Diamond DA-20 that used normal AVGAS fuel.

I was wondering, why is JET-A fuel not a standard fuel type used also for Piston Aircrafts? There are so many benefits with JET-A compared to AVGAS, and much cheaper, here is a list of benefits in my theory books, I found so far.

o An injection engine, intake system does not need icing protection.
o No throttle valves.
o No mixture control.
o Less flammable than petrol.
o Thermal efficiency is higher than petrol engine because compression ratio is higher than a petrol engine.

There are many benefits with the Diesel Engine and it's safer, and it generally just feels better flying the aircraft with Diesel, I feel the engine is more smooth and easier to start. What is the reason why JET-A fuel is not so popular on piston engines, I am really wondering about it? Here in my country converted to us dollars. One liter of JET-A fuel costs about 1 dollar per liter and AVGAS cost almost 3.1 dollars per liter.

Best Regards
Math
Last edited by SQ22 on Tue Nov 09, 2021 5:23 pm, edited 1 time in total.
Reason: Typo fixed
 
GalaxyFlyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 09, 2021 6:51 pm

Money, the new planes are very expensive
 
N1120A
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Re: Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 09, 2021 9:11 pm

Diesel engines for light aircraft are a rather new technology - less than 20 years old. There is a massive fleet of a avgas reciprocating aircraft out there, meaning the infrastructure is there as well and the cost of acquisition is much, much lower.

Also, the largest markets for light pistons - the US and Canada - do not have the same price difference.
 
LH707330
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Re: Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 09, 2021 10:08 pm

N1120A brings up a good point about the fleet makeup, it's a bit of a chicken/egg thing. Something to add to that is that few places are as familiar with overhauling diesels, so your maintenance options are more limited.

Another thing to add, diesel engines, partly due to the higher compression ratios, tend to be heavier for their power output due to their beefier structure. While they burn less fuel, their addition to empty weight means that you pay a penalty on short trips and would gain more on longer trips. Most small planes are flown for <2-hour flights, so the empty weight benefit is big.
 
N1120A
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Re: Why is Jet fuel not more popular on SE aicrafts?

Wed Nov 10, 2021 2:39 am

LH707330 wrote:

Another thing to add, diesel engines, partly due to the higher compression ratios, tend to be heavier for their power output due to their beefier structure. While they burn less fuel, their addition to empty weight means that you pay a penalty on short trips and would gain more on longer trips. Most small planes are flown for <2-hour flights, so the empty weight benefit is big.


Nah, weight isn't much of a factor. Diesels are ridiculously efficient. If anything, weight helps the CG. The DA62 is like a modern Twin Comanche, only with much more in reserve and more space.

The real issue is price. A DA50 is $1m. A used Bonanza is $200K. That is a massive difference.
 
math341c
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Re: Why is Jet fuel not more popular on SE aicrafts?

Wed Nov 10, 2021 8:30 am

Thanks for the replies guys. So the problem is mainly that the aircraft is more expensive with a Diesel Engine than Petrol Engine.
 
GalaxyFlyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Wed Nov 10, 2021 12:28 pm

That and in the US, GA is so large and so filled with relatively inexpensive old planes that a couple of diesel models don’t have much impact
 
math341c
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Re: Why is Jet fuel not more popular on SE aicrafts?

Wed Nov 10, 2021 1:03 pm

GalaxyFlyer wrote:
That and in the US, GA is so large and so filled with relatively inexpensive old planes that a couple of diesel models don’t have much impact


What do you mean by "impact". Efficiency, pollution or?
 
N1120A
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Re: Why is Jet fuel not more popular on SE aicrafts?

Wed Nov 10, 2021 8:38 pm

math341c wrote:
GalaxyFlyer wrote:
That and in the US, GA is so large and so filled with relatively inexpensive old planes that a couple of diesel models don’t have much impact


What do you mean by "impact". Efficiency, pollution or?


Impact as far as economies of scale. Some airports still don't even have Jet A. Cessna even stopped making factory diesel versions of the 172 and 182, leaving that market to Piper and Diamond. Further, Cirrus still hasn't made a diesel model of either SR, instead having their Jet A focus on their slow jet, and they dominate the non-trainer market.
 
LH707330
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Re: Why is Jet fuel not more popular on SE aicrafts?

Wed Nov 10, 2021 11:52 pm

N1120A wrote:
LH707330 wrote:

Another thing to add, diesel engines, partly due to the higher compression ratios, tend to be heavier for their power output due to their beefier structure. While they burn less fuel, their addition to empty weight means that you pay a penalty on short trips and would gain more on longer trips. Most small planes are flown for <2-hour flights, so the empty weight benefit is big.


Nah, weight isn't much of a factor. Diesels are ridiculously efficient. If anything, weight helps the CG. The DA62 is like a modern Twin Comanche, only with much more in reserve and more space.

The real issue is price. A DA50 is $1m. A used Bonanza is $200K. That is a massive difference.

When they're designed around the diesel it's fine, the issue is when you want to re-engine something. An IO-360 weighs 258 #, while an AE300 weighs 410 #. In something like a 172, those 152 # eat into your useful load if you want to take 2 buddies for a $100 hamburger.

You're right about the price of used planes, there's a bunch of well-maintained ones out there for a price differential that would pay for a lot of fuel. The DA50 looks cool though, I hope they succeed with that design.
 
N1120A
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Re: Why is Jet fuel not more popular on SE aicrafts?

Thu Nov 11, 2021 12:57 am

LH707330 wrote:
N1120A wrote:
LH707330 wrote:

Another thing to add, diesel engines, partly due to the higher compression ratios, tend to be heavier for their power output due to their beefier structure. While they burn less fuel, their addition to empty weight means that you pay a penalty on short trips and would gain more on longer trips. Most small planes are flown for <2-hour flights, so the empty weight benefit is big.


Nah, weight isn't much of a factor. Diesels are ridiculously efficient. If anything, weight helps the CG. The DA62 is like a modern Twin Comanche, only with much more in reserve and more space.

The real issue is price. A DA50 is $1m. A used Bonanza is $200K. That is a massive difference.

When they're designed around the diesel it's fine, the issue is when you want to re-engine something. An IO-360 weighs 258 #, while an AE300 weighs 410 #. In something like a 172, those 152 # eat into your useful load if you want to take 2 buddies for a $100 hamburger.

You're right about the price of used planes, there's a bunch of well-maintained ones out there for a price differential that would pay for a lot of fuel. The DA50 looks cool though, I hope they succeed with that design.


The CD155 used in Cherokees and 172s weighs a comparable amount to the IO360.

Also, useful load isn't necessarily determined by raw weight. CG and aerodynamics play into it. A Bonanza with tip tanks weighs more but has a higher useful load than one without.
 
math341c
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Re: Why is Jet fuel not more popular on SE aicrafts?

Fri Nov 12, 2021 8:03 am

@N1120A I get it thanks, simply the economics is a problem. But you say JET-A is a new technology for 20 years, for me, it's a lot for still being "New". But is believe Jet-A is successful for SE Piston. For Diamond at least the DA-40 TDI flies like a charm and the cool benefits with diesel engine is also something nice.
 
GalaxyFlyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Fri Nov 12, 2021 2:35 pm

One of the biggest factor in aviation, especially GA, is that of scale. High cost barriers due to safety certification spread over small production runs mean high unit costs. Proven technology wins over innovation. Add in large legacy installed base and new designs face a high wall.
 
LH707330
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Re: Why is Jet fuel not more popular on SE aicrafts?

Fri Nov 12, 2021 11:14 pm

N1120A wrote:
LH707330 wrote:
N1120A wrote:

Nah, weight isn't much of a factor. Diesels are ridiculously efficient. If anything, weight helps the CG. The DA62 is like a modern Twin Comanche, only with much more in reserve and more space.

The real issue is price. A DA50 is $1m. A used Bonanza is $200K. That is a massive difference.

When they're designed around the diesel it's fine, the issue is when you want to re-engine something. An IO-360 weighs 258 #, while an AE300 weighs 410 #. In something like a 172, those 152 # eat into your useful load if you want to take 2 buddies for a $100 hamburger.

You're right about the price of used planes, there's a bunch of well-maintained ones out there for a price differential that would pay for a lot of fuel. The DA50 looks cool though, I hope they succeed with that design.


The CD155 used in Cherokees and 172s weighs a comparable amount to the IO360.

Also, useful load isn't necessarily determined by raw weight. CG and aerodynamics play into it. A Bonanza with tip tanks weighs more but has a higher useful load than one without.

Is it the gearbox and accessories then that change the weight? According to this article, there's a pretty substantial empty weight penalty: https://www.aopa.org/news-and-media/all ... ot/jet-set

The main issue the authors of that article identify is the higher acquisition cost not paying for the fuel burn reduction.

Good point about the empty weight and useful load. In the case of the tip tanks, those help with bending relief, so I can see useful load going up with those. If you're adding weight in the nose though, that's probably the least helpful place to add it.
 
N1120A
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 9:22 am

math341c wrote:
@N1120A I get it thanks, simply the economics is a problem. But you say JET-A is a new technology for 20 years, for me, it's a lot for still being "New". But is believe Jet-A is successful for SE Piston. For Diamond at least the DA-40 TDI flies like a charm and the cool benefits with diesel engine is also something nice.


Jet A is not a new technology. Diesel engines in light airplanes is a new technology. Jet A and diesel are both kerosene-based, hence the ability for diesel engine aircraft to use Jet A.
 
kalvado
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 9:41 am

Correct me if I am wrong, but I had an impression that jet-a has pretty lousy specs compared to any piston fuel.
There were some interesting mentions that jet-a is not used in any rocket engines for missiles, despite military being highly interested in using existing fuel supplies for rockets. Whenever rockets fly on "kerosene", it is a much tighter spec stuff compared to jet.
Certainly jet-a has much wider operation range, compared to summer and winter formulations of diesel.
Would those be a factor for jet-a as an airplane diesel?
 
GalaxyFlyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 11:55 am

Saturn 5 F1 engines burned RP-1 which is pretty much kerosene. They used it as it was simple and known fuel.
 
kalvado
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 1:53 pm

GalaxyFlyer wrote:
Saturn 5 F1 engines burned RP-1 which is pretty much kerosene. They used it as it was simple and known fuel.

RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...
 
Okcflyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 2:41 pm

kalvado wrote:
GalaxyFlyer wrote:
Saturn 5 F1 engines burned RP-1 which is pretty much kerosene. They used it as it was simple and known fuel.

RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...


You, Sir, win anet for the day. That analogy is hilarious!

To the OP: Diesel engines also haven’t taken over the personal car market either, largely for the same cost reason, although the driver of cost is a bit different between aviation and vehicular use (emission compliance).

Mogas is probably the future of recreational aviation.
 
N1120A
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 2:56 pm

Okcflyer wrote:
kalvado wrote:
GalaxyFlyer wrote:
Saturn 5 F1 engines burned RP-1 which is pretty much kerosene. They used it as it was simple and known fuel.

RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...



Mogas is probably the future of recreational aviation.


Who said anything about recreational aviation? Recreational pilot certificates are rare, with even the vast majority of LSA pilots choosing to fly them on private instead of sport certificates and simply do so without needing a medical.
 
Okcflyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 3:59 pm

N1120A wrote:
Okcflyer wrote:
kalvado wrote:
RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...



Mogas is probably the future of recreational aviation.


Who said anything about recreational aviation? Recreational pilot certificates are rare, with even the vast majority of LSA pilots choosing to fly them on private instead of sport certificates and simply do so without needing a medical.


Come on man. Recreational as in “non-commercial” uses. Like the $100 hamburger example.

Your standard VFR & IFR types. Most of GA is for recreational purposes. Hence the point in trying to convey.
Last edited by Okcflyer on Sat Nov 13, 2021 4:16 pm, edited 1 time in total.
 
GalaxyFlyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 4:03 pm

kalvado wrote:
GalaxyFlyer wrote:
Saturn 5 F1 engines burned RP-1 which is pretty much kerosene. They used it as it was simple and known fuel.

RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...


Yeah, it more refined, less sulfur and impurities to polymerize during high temperatures; but it’s kerosene just as
they’re both water. RP-1 would burn fine in jet engine and you wouldn’t go to the moon and both waters would sustain life.

The one issue with using JetA in a piston engine is lubricity in the pumps and injectors as some found out using Jet A in their diesel cars.
 
kalvado
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Re: Why is Jet fuel not more popular on SE aicrafts?

Sat Nov 13, 2021 4:43 pm

GalaxyFlyer wrote:
kalvado wrote:
GalaxyFlyer wrote:
Saturn 5 F1 engines burned RP-1 which is pretty much kerosene. They used it as it was simple and known fuel.

RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...


Yeah, it more refined, less sulfur and impurities to polymerize during high temperatures; but it’s kerosene just as
they’re both water. RP-1 would burn fine in jet engine and you wouldn’t go to the moon and both waters would sustain life.

The one issue with using JetA in a piston engine is lubricity in the pumps and injectors as some found out using Jet A in their diesel cars.

But rocket engine may or may not not run on Jet-A. So the question is if piston diesel would run equally well on every batch of Jet-A (add oil for lubricity as needed)

As for historic aspect, there is a great book "Ignition!" by John D. Clark, scientist who worked in rocket fuel development in 50-60s
https://library.sciencemadness.org/libr ... nition.pdf and the relevant passage is on pp 35-36.
From the beginning, the services had disliked the fuels that the researchers had offered them, not only because of their inherent disadvantages, but above all because they weren't gasoline. They already had gasoline and used huge quantities of it —and why should they have to bother with something else? But, as we have seen, gasoline is not a good fuel to b u r n with nitric acid, and the services had to accept the fact. Which they did, grudgingly. But all through the late 40's and early 50's the Navy and the Air Force were busily changing over from piston airplane engines to turbojets. And they started buying jet fuel instead of gasoline, and the whole thing started all over again. They d e m a n d e d of the people designing their missiles that said missiles be fueled with jet fuel.
Now, what is jet fuel? T h a t depends. A turbojet has a remarkably undiscriminating appetite, and will run, or can be made to r u n , on just about anything that will b u r n and can be made to flow, from coal dust to hydrogen. But the services decided, in setting u p the specifications for the jet fuel that they were willing to buy, that the most important considerations should be availability and ease of handling.
 
atcdan
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Re: Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 16, 2021 4:39 am

This is analogous to “I’m saving 70% on fuel by driving a Tesla, why doesn’t everyone own one?”

Most people cannot afford a brand new 50k car, and even when they can, the concerns about longevity, infrastructure, and changes in habits play a big role.
 
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zeke
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Re: Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 16, 2021 12:00 pm

Other factors will result in changes, in many parts of the world AVGAS is harder to obtain, and when you can obtain it is prior planned drumstock. AVGAS is simply not a very commercially viable fuel to either manufacture or transport.

The other aspect of Diesel engine uptake is the engine type either needs to be on the airframe TCDS or an STC to allow the aircraft to be registered other than experimental category.

I think the entry level trainers will end up being electric
 
math341c
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Re: Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 16, 2021 12:26 pm

Mogas is probably the future of recreational aviation.


What do you mean by that? Is MOGAS being the future for GA aviation? Just take any "General Aircraft Knowledge" book and read the disadvantages of using MOGAS for piston engines.

Btw, have you seen the websites of Airbus and Diamond? Diamond has presented their electrical aircraft, the future will be electrical aircraft as with electrical cars.
 
Okcflyer
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Re: Why is Jet fuel not more popular on SE aicrafts?

Tue Nov 16, 2021 4:04 pm

math341c wrote:
Mogas is probably the future of recreational aviation.


What do you mean by that? Is MOGAS being the future for GA aviation? Just take any "General Aircraft Knowledge" book and read the disadvantages of using MOGAS for piston engines.

Btw, have you seen the websites of Airbus and Diamond? Diamond has presented their electrical aircraft, the future will be electrical aircraft as with electrical cars.


I should have been more specific .... MOGAS derived fuels (unleaded!) such as UL91 and UL100.

The trade off of using unleaded fuels gets significantly smaller with modern, high speed electronic controls such as Lycomings iE2 package.

For environmental and cost/complexity reasons, low-lead avgas will go away at some point and that will put pressure on the GA industry to adapt. And it's a lot easier and cheaper to move to UL91/100 and electronic controls (which are retrofittable) than to diesel cycle running Jet A / A1. This was the nature of my point.
 
N1120A
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Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Nov 29, 2021 8:16 am

Okcflyer wrote:
math341c wrote:
Mogas is probably the future of recreational aviation.


What do you mean by that? Is MOGAS being the future for GA aviation? Just take any "General Aircraft Knowledge" book and read the disadvantages of using MOGAS for piston engines.

Btw, have you seen the websites of Airbus and Diamond? Diamond has presented their electrical aircraft, the future will be electrical aircraft as with electrical cars.


I should have been more specific .... MOGAS derived fuels (unleaded!) such as UL91 and UL100.

The trade off of using unleaded fuels gets significantly smaller with modern, high speed electronic controls such as Lycomings iE2 package.

For environmental and cost/complexity reasons, low-lead avgas will go away at some point and that will put pressure on the GA industry to adapt. And it's a lot easier and cheaper to move to UL91/100 and electronic controls (which are retrofittable) than to diesel cycle running Jet A / A1. This was the nature of my point.


Using the term mogas to describe unleaded aviation fuels is as poorly taken as calling flying light aircraft "recreational." Neither term is accurate or precise. Unleaded aviation fuel, particularly 100UL, is still AvGas. 100UL, which GAMI appears to have finally developed reliably, is gasoline that reliably is the same octane level as 100LL but without lead added to ensure that.

Mogas describes automotive grade gasoline, meaning 87 octane.
 
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Phosphorus
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Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Dec 13, 2021 12:49 pm

N1120A wrote:
Okcflyer wrote:
math341c wrote:

What do you mean by that? Is MOGAS being the future for GA aviation? Just take any "General Aircraft Knowledge" book and read the disadvantages of using MOGAS for piston engines.

Btw, have you seen the websites of Airbus and Diamond? Diamond has presented their electrical aircraft, the future will be electrical aircraft as with electrical cars.


I should have been more specific .... MOGAS derived fuels (unleaded!) such as UL91 and UL100.

The trade off of using unleaded fuels gets significantly smaller with modern, high speed electronic controls such as Lycomings iE2 package.

For environmental and cost/complexity reasons, low-lead avgas will go away at some point and that will put pressure on the GA industry to adapt. And it's a lot easier and cheaper to move to UL91/100 and electronic controls (which are retrofittable) than to diesel cycle running Jet A / A1. This was the nature of my point.


Using the term mogas to describe unleaded aviation fuels is as poorly taken as calling flying light aircraft "recreational." Neither term is accurate or precise. Unleaded aviation fuel, particularly 100UL, is still AvGas. 100UL, which GAMI appears to have finally developed reliably, is gasoline that reliably is the same octane level as 100LL but without lead added to ensure that.

Mogas describes automotive grade gasoline, meaning 87 octane.


Interesting. In Europe, finding car fueling station, with gasoline of less than 92 octane at fueling stations is a challenge, with 95 octane being the mainstay, 98 being premium blends, and plenty of upmarket stations carrying 100 octane.

Okcflyer wrote:
kalvado wrote:
GalaxyFlyer wrote:
Saturn 5 F1 engines burned RP-1 which is pretty much kerosene. They used it as it was simple and known fuel.

RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...


You, Sir, win anet for the day. That analogy is hilarious!

To the OP: Diesel engines also haven’t taken over the personal car market either, largely for the same cost reason, although the driver of cost is a bit different between aviation and vehicular use (emission compliance).

Mogas is probably the future of recreational aviation.


Depends on where. If refiners leave 0.5% of sulfur or more in the fuel, diesel personal cars are not a thing.
If regulations are tougher, and diesel fuel is better, personal cars are easily shifting towards diesel. From memory, EU is generally around ~50% of all new car sales diesel, with France as much as 60%?
So yes, in some regions, diesel cars have very much taken over personal car market.
But, these same cars would have a challenge, if constantly run on Jet A, rather than diesel fuel, as lubricity (or rather lack thereof) would prove a problem. These are common rail diesels, often turbocharged.
 
kalvado
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Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Dec 13, 2021 1:20 pm

Phosphorus wrote:
N1120A wrote:
Okcflyer wrote:

I should have been more specific .... MOGAS derived fuels (unleaded!) such as UL91 and UL100.

The trade off of using unleaded fuels gets significantly smaller with modern, high speed electronic controls such as Lycomings iE2 package.

For environmental and cost/complexity reasons, low-lead avgas will go away at some point and that will put pressure on the GA industry to adapt. And it's a lot easier and cheaper to move to UL91/100 and electronic controls (which are retrofittable) than to diesel cycle running Jet A / A1. This was the nature of my point.


Using the term mogas to describe unleaded aviation fuels is as poorly taken as calling flying light aircraft "recreational." Neither term is accurate or precise. Unleaded aviation fuel, particularly 100UL, is still AvGas. 100UL, which GAMI appears to have finally developed reliably, is gasoline that reliably is the same octane level as 100LL but without lead added to ensure that.

Mogas describes automotive grade gasoline, meaning 87 octane.


Interesting. In Europe, finding car fueling station, with gasoline of less than 92 octane at fueling stations is a challenge, with 95 octane being the mainstay, 98 being premium blends, and plenty of upmarket stations carrying 100 octane.

Okcflyer wrote:
kalvado wrote:
RP-1 compares to Jet-a pretty much same way as distilled apyrogenic water for IV injections compares to rainwater in backyard barrel. Both are water...


You, Sir, win anet for the day. That analogy is hilarious!

To the OP: Diesel engines also haven’t taken over the personal car market either, largely for the same cost reason, although the driver of cost is a bit different between aviation and vehicular use (emission compliance).

Mogas is probably the future of recreational aviation.


Depends on where. If refiners leave 0.5% of sulfur or more in the fuel, diesel personal cars are not a thing.
If regulations are tougher, and diesel fuel is better, personal cars are easily shifting towards diesel. From memory, EU is generally around ~50% of all new car sales diesel, with France as much as 60%?
So yes, in some regions, diesel cars have very much taken over personal car market.
But, these same cars would have a challenge, if constantly run on Jet A, rather than diesel fuel, as lubricity (or rather lack thereof) would prove a problem. These are common rail diesels, often turbocharged.

US and EU octane numbers are not the same. 87 in US is about 92-93 in EU. It is about different methods of measurements.
And sulfur removal is not free. Cost may be offset by taxation and fees, but that is a totally different story. And issues with additives are a total different story. Black magic of oil and fuel formulations is just that, black magic. Base fractions have to be similar
 
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Phosphorus
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Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Dec 13, 2021 1:33 pm

kalvado wrote:
Phosphorus wrote:
N1120A wrote:

Using the term mogas to describe unleaded aviation fuels is as poorly taken as calling flying light aircraft "recreational." Neither term is accurate or precise. Unleaded aviation fuel, particularly 100UL, is still AvGas. 100UL, which GAMI appears to have finally developed reliably, is gasoline that reliably is the same octane level as 100LL but without lead added to ensure that.

Mogas describes automotive grade gasoline, meaning 87 octane.


Interesting. In Europe, finding car fueling station, with gasoline of less than 92 octane at fueling stations is a challenge, with 95 octane being the mainstay, 98 being premium blends, and plenty of upmarket stations carrying 100 octane.

Okcflyer wrote:

You, Sir, win anet for the day. That analogy is hilarious!

To the OP: Diesel engines also haven’t taken over the personal car market either, largely for the same cost reason, although the driver of cost is a bit different between aviation and vehicular use (emission compliance).

Mogas is probably the future of recreational aviation.


Depends on where. If refiners leave 0.5% of sulfur or more in the fuel, diesel personal cars are not a thing.
If regulations are tougher, and diesel fuel is better, personal cars are easily shifting towards diesel. From memory, EU is generally around ~50% of all new car sales diesel, with France as much as 60%?
So yes, in some regions, diesel cars have very much taken over personal car market.
But, these same cars would have a challenge, if constantly run on Jet A, rather than diesel fuel, as lubricity (or rather lack thereof) would prove a problem. These are common rail diesels, often turbocharged.

US and EU octane numbers are not the same. 87 in US is about 92-93 in EU. It is about different methods of measurements.
And sulfur removal is not free. Cost may be offset by taxation and fees, but that is a totally different story. And issues with additives are a total different story. Black magic of oil and fuel formulations is just that, black magic. Base fractions have to be similar

Of course sulfur removal isn't free. Neither was taking lead out of gasoline. Still, these are the right thing to do.
Heck, even marine fuels now were desulfurized under IMO regulation, despite shipping industry having to be dragged to it, kicking and screaming...

But if public and regulators are fine with truck exhausts basically spewing sulfurous and sulfuric acid, that's it.

On octane -- I'm not sure I get you right. There are two ways to measure octane -- "motor method" and "bench method" (sorry if I'm getting words wrong, English is not my first, nor second, language, and I'm translating from memory on the go). European way is to put label per bench method (slightly higher), but always document motor method level. You mean, in the US, folks ignore bench measurement, and only document "motor method" measurement?
 
kalvado
Posts: 3664
Joined: Wed Mar 01, 2006 4:29 am

Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Dec 13, 2021 1:48 pm

Phosphorus wrote:
kalvado wrote:
Phosphorus wrote:

Interesting. In Europe, finding car fueling station, with gasoline of less than 92 octane at fueling stations is a challenge, with 95 octane being the mainstay, 98 being premium blends, and plenty of upmarket stations carrying 100 octane.



Depends on where. If refiners leave 0.5% of sulfur or more in the fuel, diesel personal cars are not a thing.
If regulations are tougher, and diesel fuel is better, personal cars are easily shifting towards diesel. From memory, EU is generally around ~50% of all new car sales diesel, with France as much as 60%?
So yes, in some regions, diesel cars have very much taken over personal car market.
But, these same cars would have a challenge, if constantly run on Jet A, rather than diesel fuel, as lubricity (or rather lack thereof) would prove a problem. These are common rail diesels, often turbocharged.

US and EU octane numbers are not the same. 87 in US is about 92-93 in EU. It is about different methods of measurements.
And sulfur removal is not free. Cost may be offset by taxation and fees, but that is a totally different story. And issues with additives are a total different story. Black magic of oil and fuel formulations is just that, black magic. Base fractions have to be similar

Of course sulfur removal isn't free. Neither was taking lead out of gasoline. Still, these are the right thing to do.
Heck, even marine fuels now were desulfurized under IMO regulation, despite shipping industry having to be dragged to it, kicking and screaming...

But if public and regulators are fine with truck exhausts basically spewing sulfurous and sulfuric acid, that's it.

On octane -- I'm not sure I get you right. There are two ways to measure octane -- "motor method" and "bench method" (sorry if I'm getting words wrong, English is not my first, nor second, language, and I'm translating from memory on the go). European way is to put label per bench method (slightly higher), but always document motor method level. You mean, in the US, folks ignore bench measurement, and only document "motor method" measurement?

US gas is labeled with (M+S)/2, so US label for same fuel is 5-6 points below what would be used elsewhere.

Lead, unlike sulfur, had multiple purposes from octane number to valve lubrication. It was added by xhoice.
Sulfur removal is just that, removal of natural part of oil coming from the well, which means direct and indirect removal costs, and - from the manufacturing perspective - adding no value beyond legal compliance. Gas may have less complicated process flow, hence price.
 
TheSonntag
Posts: 4679
Joined: Wed Jun 15, 2005 7:23 pm

Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Dec 13, 2021 4:07 pm

The CD-155 engine (Thielert 2.0) did take some time to mature. Unfortunately, what you save in fuel, you pay in maintenance, as the engine is more complex than the Lycomings.

I believe you will not really see new piston engines for aviation (exception the new German-Russian V12 and the Thielert developments), instead we will soon get lead free Avgas for legacy engines and electric/hydrogen for GA planes.
 
User avatar
Phosphorus
Posts: 1511
Joined: Tue May 16, 2017 11:38 am

Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Dec 13, 2021 4:18 pm

Burning high-sulfur fuels is not only a compliance matter, nor just emissions matter either. High-sulfur fuels impede progress in lubricants and engine design, as you have to basically overbase your motor oil, and plan for oil degradation and frequent oil change. No chance for fancy stuff, as your oil is (frequently) disposable. So you load your oil with a bunch of high-overbased additives, and spend most of your technology on managing oil degradation by acidic cocktail, trying to slow it down, and preventing engine damage.

In low-sulfur-fuel ecosystem, you can move on. Admittedly, it's been a while since I last seriously looked at all of this, but European oil additive-lube oil-engine builder folks, more than 15 years ago, already were running tests with no-oil-change-until-engine-rebuild truck engines. There was no even opening to add oil, as oil was supposed to work and work and work, until engine was taken out and rebuilt -- and/or replaced.

But yeah, instead of taking sulfur out and burning it (in clean special furnaces) to make acid for industrial use, you just throw that same sulfuric acid into atmosphere. Happy breathing, enjoy your acid rains folks! (Yeah, I jest, but this is basically what it ends up at...)
 
GSOtoIND
Posts: 195
Joined: Mon Aug 13, 2018 10:46 pm

Re: Why is Jet fuel not more popular on SE aicrafts?

Mon Dec 13, 2021 4:50 pm

Phosphorus wrote:
kalvado wrote:
Phosphorus wrote:

Interesting. In Europe, finding car fueling station, with gasoline of less than 92 octane at fueling stations is a challenge, with 95 octane being the mainstay, 98 being premium blends, and plenty of upmarket stations carrying 100 octane.



Depends on where. If refiners leave 0.5% of sulfur or more in the fuel, diesel personal cars are not a thing.
If regulations are tougher, and diesel fuel is better, personal cars are easily shifting towards diesel. From memory, EU is generally around ~50% of all new car sales diesel, with France as much as 60%?
So yes, in some regions, diesel cars have very much taken over personal car market.
But, these same cars would have a challenge, if constantly run on Jet A, rather than diesel fuel, as lubricity (or rather lack thereof) would prove a problem. These are common rail diesels, often turbocharged.

US and EU octane numbers are not the same. 87 in US is about 92-93 in EU. It is about different methods of measurements.
And sulfur removal is not free. Cost may be offset by taxation and fees, but that is a totally different story. And issues with additives are a total different story. Black magic of oil and fuel formulations is just that, black magic. Base fractions have to be similar

Of course sulfur removal isn't free. Neither was taking lead out of gasoline. Still, these are the right thing to do.
Heck, even marine fuels now were desulfurized under IMO regulation, despite shipping industry having to be dragged to it, kicking and screaming...

But if public and regulators are fine with truck exhausts basically spewing sulfurous and sulfuric acid, that's it.

On octane -- I'm not sure I get you right. There are two ways to measure octane -- "motor method" and "bench method" (sorry if I'm getting words wrong, English is not my first, nor second, language, and I'm translating from memory on the go). European way is to put label per bench method (slightly higher), but always document motor method level. You mean, in the US, folks ignore bench measurement, and only document "motor method" measurement?

In America we use AKI, the Anti-Knock Index, which is the average of the RON and MON, while most of the world uses RON on its own. MON is the Motor Octane Number and is supposed to be more realistic than the Research Octane Number. Your 98 RON is roughly equivalent to the 93 octane premium that's typically available at most stations, though California and high altitude states top out at 91.

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