If I were to put on my conspiratorial hat, I would guess the reason for stalling is that approving the G100UL fuel from General Aviation Modification, Inc. (GAMI) will divert profits from Shell and ExxonMobil, both of which provide significant funding for the two US political parties.
In fact, I would not at all be surprised to see approval delayed until such time as Shell or ExxonMobil can develop a competitor -- not an exact copy of GAMI's fuel, but something close enough to not violate the patent.
GAMI is tiny (and privately held). You could tour their entire facilities in a fascinating afternoon.
Whether they could be bought is a matter of choice by the owners. It’s not that Shell or Exxon couldn’t afford them, but the principals might choose not to sell for a price that’s attractive to the oil companies.
While I'm not disagreeing, according to WikiPedia the amount of 100LL sold per year is 0.14% of that of MoGas (2008). https://en.wikipedia.org/wiki/Avgas#Consumption Shell, Exxon, etc. probably see AvGas as a pain.
Regardless of who you are in the government, the safest answer to anything is no. Permit housing? No. Permit power lines? No. Permit a nuclear plant? No. Permit an aviation fuel? No. Permit cross-laminated timber? No.
Nobody gets fired for saying no. This is how greatness fades away and a nation becomes uselessly sclerotic and irrelevant.
Historically this has not been true. The more ossified the bureaucracy becomes the less able it is to adapt and innovate which eventually leads to replacement or revolution.
Ossification leads to instability for numerous reasons, not the least of which being that it encourages people to just ignore authorities and go around them. This leads to a culture of routine corruption where people break the law just to get things done, which can lead to a full-blown mafia state or to collapse and revolution.
Is that really true though? Do you have an example of bureaucratic ossification leading to a mafia state? Is there evidence that is how any mafia or mafia state has arises? Is there any evidence that bureaucracy has played a role in a revolution or was a causal factor?
I'd be interested to know if you do get examples. Also interested to know whether you were able to find evidence and examples for the prior claim that "It's also how stability is maintained and a nation remains safe and trustworthy."
Spot on. I've worked govt adjacent. It's basically a "can't do" mentality vs a "can do" mentality. Politically same issue. Endless politicians "outraged" and "offended" by various things - so keeping your head down, doing it the same way you've done it before is seen as the safest internally. Now layer in a ton of non-performance or deliverables oriented goals and things just grind down to a total halt.
Is is telling that aviation’s “sustainable fuel” vision is the same Fischer-Tropsch chemistry that’s been abandoned for everything else because the capital cost of the machinery is too damn high.
Ground transportation has moved on to single-entity fuels that are synthesizable like 1-butanol and dimethyl ether. I can’t for the life of me see why the industry isn’t developing methane as an aviation fuel as it could even be the low cost solution in 2022 if Airbus had developed that instead of the thoroughly pizzled A380.
Methane was investigated as aviation fuel, and was found to be more problematic than Hydrogen - in fact, it's even less forgiving than hydrogen due to taking longer to dissipate and having worse side effects in case of accidental tank rupture.
In fact, the only viable use of Methane in aviation fuels was by 2007 considered to be... feedstock for Fischer-Tropsch chemistry, which also can make carbon-neutral syntin that will require no complete rebuilds of planes and engines.
> Regardless of who you are in the government, the safest answer to anything is no.
This is not always true. I'm a former patent examiner. At the US patent office, sometimes granting a patent (answering yes) is the safest response. If an examiner can't find a reason to reject the application in the time they are given, what choice do they have? Their decisions can't be arbitrary.
That's actually an example in favor of the OP's point, because patents are restrictive in nature rather than permissive. Accepting the patent doesn't permit anyone to do anything, it represents the government removing the ability of anyone but the claimant to do what they're claiming.
(Aside: I wonder what the effects would be of inventing and patenting environment-destroying technologies, then refusing to license them to delay their implementation. The patent system allows anyone to ban a technology, if they can convince the examiner they invented it.)
Could be semantics, I guess. Patent examiners permit operation of monopolies in my view.
> (Aside: I wonder what the effects would be of inventing and patenting environment-destroying technologies, then refusing to license them to delay their implementation. The patent system allows anyone to ban a technology, if they can convince the examiner they invented it.)
I imagine polluting companies would ignore the patents ("efficient infringement") and/or try to invalidate the patents.
>Patent examiners permit operation of monopolies in my view.
The operation of a monopoly was already possible before the patent via trade secrets (typical contemporary example, SpaceX), what the patent does is make it illegal to break the monopoly by re-inventing the technology.
It all makes much more sense if you consider the world from the following hypothetical utility function of the FAA: to maximize net present value of funding.
If they are 50% efficient, or even 10% efficient, they won't be eliminated. They're still needed for certain basic operations in aviation.
However, if they do something with a 30% chance of a great outcome from aviation, and 1% chance of a negative scandal, that negative risk outweighs any positivity.
In my experience (decades of direct interaction) most of the FAA is a model of professionalism in civil service. But there are pockets of sheer insanity, usually due to perverse incentives like what you're describing. This whole fiasco has all the hallmarks of pathological risk-aversion. No one wants to be the one who said "yes" because there's no punishment for saying "no." The FAA's approach to risk management is, in general, second-to-none, but when it isn't paired with a mission assurance mindset, you get pathological outcomes like this.
Five hundred and thirty seven people killed from the 737 max scandal, which showed the FAA was basically not providing any oversight of Boeing whatsoever, and even worse, was complicit in coverups: https://www.theverge.com/2020/12/18/22189609/faa-boeing-737-...
That lack of supervision included the FAA providing little or no oversight over Boeing using lithium ion batteries without sufficient testing, resulting in several fires on airliners.
Treating air traffic controllers so poorly - including underpaying them by nearly thirty percent, that they went on strike, and refusing to give them a shorter work week to compensate for the high stress nature of the job: https://en.wikipedia.org/wiki/Professional_Air_Traffic_Contr...
and since then, we've had decades upon decades of overworked, overstressed, understaffed air traffic controllers, which results in problems ranging from crashes due to errors to falling asleep to substance abuse:
A controller in Las Vegas has a stroke and was speaking gibberish for half an hour before anyone in the control tower noticed, likely because she was working alone and unsupervised.
Am I forgetting anything?
"Model of professionalism in civil service" my ass. This debacle over fueling is just yet another way the FAA has pointlessly stood in the way of progress to protect vested industry interests. FAA regulations are rife with all sorts of absurd shit barring a private pilot from modernizing their planes in cost effective manner or enhancing them with greater avionics capabilities.
Yes, the words "most" and "pockets of sheer insanity." I am not so simple-minded as to view an entire agency as a single, atomic entity. I recognize what they do well and am one of the harshest critics of what they do poorly, especially when the results are death. This is something I hoped I had conveyed in my original post.
> [you] can (…) jump off a cliff in a flight suit,
This is in fact an argument against FAA: you can risk your life in many other ways in many other contexts not regulated by FAA, so why not be allowed to risk your own life in a regulated field?
Because it involves risking other people's lives? I think that's pretty obvious, so maybe I'm missing something. You also can't risk your own life by driving on the wrong side of the highway.
No, it does not involve any of that. You just assume that because it is convenient for your argument, but the truth is that there are plenty of ways to risk your own life flying with negligible risk to anyone else.
Think, for example, about racing home made cars on salt flats: perfectly legal, even though you could conceivably hit someone who just happens to stroll by. Why can’t I race my home made plane over salt flats?
Also, even if you follow FAA rules, you’re still risking other people lives. Pretty much every nontrivial activity is potentially lethal to bystanders, and flying is even more so. Despite that, flying is still allowed in general. You cannot argue “activity X that has some minor risk to you and nonzero risk to bystanders should be disallowed, because you must not expose bystanders to risk”, when you are already allowed to expose them to bigger risks in other ways in the context of the same regulated activity.
You do not want to engage my actual argument, which is why you are trying to reframe it in a context where it is absurd. Of course I’m not suggesting that people should be allowed to drive 100 mph on the wrong side of busy freeway, and the reason you need to suggest that I do is that you are unable to engage what I actually say.
> You just assume that because it is convenient for your argument
You don't need to attack people or be paranoid about their motives; you could use a little trust and reason, maybe even a sense of humor. I didn't read the comment after that, but I can see italics and other signs of another angry, self-righteous outburst. I guess everyone else on the Internet does it, so why not? It's working so well for our society.
From my understanding, in most places in USA ATC is provided by private enterprises contracted for the role, not as civil service - a direct effect of the Reagan crackdown.
This has interesting knock on effects, for example if private company ATC fucks up and gives you bad information, you don't have much in terms of options for example to dispute charges that you deliberately violated a presidential no fly zone.
> for example if private company ATC fucks up and gives you bad information, you don't have much in terms of options for example to dispute charges that you deliberately violated a presidential no fly zone.
Why would ATC being public or private contractor for public agency change your legal situation here?
The case I heard of, which did involve bad information leading to getting intercepted, the fact that the ATC was subcontracted to private organization meant that it was extra hard (if not impossible, at the time I've read about the case they were still trying to find a way) to get any information regarding ATC operation that could at least lead to a witness for the trial.
If you’re given wrong wrong instruction by a public agency, it is highly likely that you have literally no recourse whatsoever, due to sovereign and qualified immunity.
Not really - you can request FOIA or equivalent records and the like and use them for example to defend yourself, even if the agency can't be sued - and qualified immunity IIRC did not apply to civil service ATC, nor did sovereign immunity.
Yes! They completely failed to notice that 5G was a thing, and that thing was going to be deployed everywhere, including near airports. They had like a decade to plan for it and any potential impact it might have on planes.
Now they're panicking and trying to hold up a nationwide 5G rollout because they were asleep at the wheel.
Even worse than being asleep at the wheel, that may have been a political power play between the FCC and the FAA, each trying to increase their power and budget, with consumers getting the raw end of the deal...
They weren't asleep at the wheel - pretty sure they were involved in discussions that led to larger guard bands etc deployed elsewhere.
FCC is the one that sold problematic spectrum before work was done (and yes, work was being done, and it's not trivial to deal with spectrum change like that)
Disagree. They've betrayed the aviation community more than once in recent times. Let's go back a few years to when Michael Huerta sold everyone out by striking a secret back-room deal with the Santa Monica city council to give one of our iconic (and federally-owned) GA airports to corrupt local politicians to be destroyed. Oh, AND he allowed the city to shorten the runway to make it unusable to some jets. Why do BOTH? Shortening the runway eliminated the only shred of a basis for complaint coming from anyone in the area, so there was no excuse for any further selling-out. To this day we don't know exactly what kind of political quid pro quos took place in this shameful episode.
Then there was the ridiculous ruling that it was illegal for people to receive pilot training in their own airplanes, contradicting decades of prior practice and rule interpretation. That had to be undone by Congress: https://www.flyingmag.com/flight-instruction-faa/
But hey, I will add a positive note: BasicMed is a huge step forward. It's sad that it took as long as it did to achieve this reform, but allowing a great portion of the pilot community to avoid the scammy expense and hassle of finding a "special" FAA doctor for a regular physical is a huge relief.
The fact that basicmed contained absolutely no affordances for well-managed mental health conditions shows that basicmed was also a serious administrative failure, though.
> And recently there was a ruling that essentially made go-arounds (aborted landings) illegal (if the testimony here is true: https://www.youtube.com/watch?v=RpFDRoStcd4 ).
Why not link to the actual ruling instead of some random YouTube video when making such a far-fetched claim?
> Nobody gets fired for saying no. This is how greatness fades away and a nation becomes uselessly sclerotic and irrelevant.
Where does this come from? Things are permitted and developed all the time. In fact, many perceive government as overly lenient to big business, leading to disasterous results (like the Boeing plane crashes).
There's a wide gap between zero regulation and a bureaucracy that always says 'no'. A lot of our problems right now are the result of 'no'. Nationally we're short almost 4 million homes because zoning law has said 'no' to more and more-diverse housing. California suffers rolling blackouts in part because regulations have simultaneously made it difficult to maintain existing transmission lines or build new ones. Maine residents just voted down building a transmission line to bring low-carbon hydro power in from Canada. We've been suffering a self-inflicted baby shortage formula for many reasons, but not least because we made it difficult to import the stuff.
I'm from Maine. The transmission line was voted down because CMP (a widely hated organization) was basically getting free use of land for no reason. The power was strictly going to Massachusetts
A few instances (even if supported by evidence, and where the benefits didn't outweight the costs) says zero about the overall situation in an enormous country. Is there evidence of the overall situation?
The small government / empower big business lobby likes to use the rhetoric of repetition-until-it-seems-like-fact, but that doesn't make it true.
This is completely connected with the FAA holding 5G frequencies hostage because it can’t make airlines replace faulty altimeters. Phone companies should have sued the manufacturers of those things.
And would have no success, because under FCC rules the telecoms are the closest ones to violating the rules (their emissions are causing problems for others, receiving is not regulated) and moreover, it was FCC decision to go with much smaller guard band and not require various preventive measures.
The altimeters aren't faulty, and everywhere else the regulatory bodies for aviation, radio spectrum, aviation industry and telcos cooperated on figuring things out. Unfortunately for USA, physics doesn't bend just to accommodate bad management of radio spectrum and hilariously bad mobile telco market.
It wasn't really the FAA, the FCC just blindly started auctioning off spectrum before thinking to test anything. If they'd left a larger buffer between the bands this wouldn't be an issue but $$$.
To me, this is yet another case for reducing the number of large federal governing bodies. Shouldn't the fuel approved for use be a state (or local airport) decision in all but federal military airfields?
It would be an overall nightmare if aviation was regulated state-by-state.
I’m generally in favor of “as local as practical”, but I think that the FAA, FCC, CDC, EPA, and a few others are cases where “as local as practical” ends up being federal.
The better question is, if this an obvious improvement over the current solutions, then what is it specifically that prevents this governing body from allowing the change? And, wouldn't that same issue be a worse problem for a smaller and less well funded governing body?
While I believe G100UL is an improvement over 100LL in every important dimension except cost (where the delta is small enough to be accepted) and a small density penalty (a gallon is 5% heavier than 100LL, but contains slightly more energy as an offsetting factor, but “full tanks” will now be heavier and if the fuel has been mixed, it’ll be heavier by an unknown amount), it still needs an amount of test cell and flight testing to demonstrate that it’s equal or better.
Right now, the law says “these airplanes are allowed to use these engines”, “these engines are allowed to use 100LL”, and “100LL has the following composition”. To be legal, you need paperwork that breaks one or more of those constraints, which is what GAMI is in the process of pursuing. To get that paperwork, they have to demonstrate functional equivalence and convince the FAA to issue a supplemental type certificate (the legal paperwork that would alter the second condition above). It’s not unreasonable for the FAA to need proof. Whether they need more proof than they have is self-evidently a point of disagreement between GAMI and their supporters (I count myself among this set) and the FAA.
Different states have different requirements for gasoline and that seems to work just fine. Gas in California has higher ethanol content than most states. Oregon requires that someone else pump your gas. All the states have different taxes on gasoline. Yet you can gas up in one state and drive to another without issue.
Because cars have been designed to deal with it since the 80s at least. Airplanes not so. Sure, we could begin to manufacture airplanes with more tolerance for different gasolines (and in fact we have; many modern high compression aircraft engines can take unleaded car gas), but it's taken decades to get to even this point.
Not in the slightest. Aviation gasoline is heavily regulated because it has to work flawlessly in every (piston) aircraft engine. 100LL exists because it has an extremely low knock rate; any new regulation needs to maintain that. This is a safety issue, not a political one.
Air travel sure seems a lot like interstate commerce - will planes need different fuel at each state border? Plus, I'd rather have the professionals at the FAA rather than whoever works in each state government.
What engines really don't like is constantly switching between leaded and unleaded fuel. Deciding that on a per-state basis would mean you'd need a California plane that only operates in California, and another Nevada plane for Nevada. Crossing the state line would become dangerous. Cross-country GA would quickly die that way.
Or...if California banned leaded aviation fuel. All airports wanting to service CA airplanes would need to offer unleaded aviation fuel. Thus accelerating the change quickly with market forces.
Somehow cross country travel works without issue. Not sure how that is so different from a state "FAA" type agency.
Cars - when the switch came from leaded to unleaded fuel - were more robust machines by an order of magnitude, and engine failure in cars means you have to call a garage. Engine failure in a plane means you are likely dead.
I'm all for market forces - where they make sense. In aviation, oversight saves lives.
This might be true in the short-term but unfortunately all the oversight means that a huge proportion of GA aircraft are still running carbureted engines with manual mixture control.
Modern car engines are generally much more reliable than cars made 40+ years ago. It's quite possible that this oversight is actually costing lives by limiting innovation.
Outside of hobbyist circles (may their brains match their guts), car engines in planes have a rocky history.
There was a big push in the 1990s to put "modern car engines" into GA planes, mostly diesel. It ... didn't go well. Turns out these car-derived engines were a lot less reliable than the good old Lycoming IO series, and much more expensive to maintain due to higher complexity (not to mention heavier, which always is a concern with airframes). And then there was the question on how long the manufacturer would provide replacement parts...
There is a push to make car engines happen with some EU-based manufacturers, most notably Diamond Aircraft, today. We'll see how that works.
Add that to the fact that new aircraft are prohibitively expensive, and we'll see manual mixture control-based engines for decades to come.
Technocracy + bureaucracy = sloth. There's no incentive to risk anything. You aren't directly answerable to the people whom you consider beneath you anyway. Nothing improves.
If FAA won't do their job, then that power (such as it is) needs to be stripped from them and invested back in Congress.
The FAA is an agency within the DOT, under the executive branch, answerable to the legislative and judicial branches. Congress has pretty significant supervision legislatively and budgeting-wise.
Presumably GABI has talked to some congressional reps. So the question is: why aren't they lighting a fire under the FAA's ass to at least follow their own regulations? This seems more than worthy of a congressional hearing. Frankly, AOPA should have demanded as much, but they're probably too worried about pissing off Lycoming and Continental.
GABI also has the option to pursue redress via the courts. I don't know whether they've attempted to do so or not.
The delegation of authority from Congress to the FAA doesn't stop Congress from telling the FAA what to do. Congress can still pass, and has passed, legislation directing the FAA to take specific action on specific matters, and there's absolutely nothing the FAA can do about it other than comply. Congress can absolutely step in here if it wants to.
Congress delegated the authority to the FAA because (in concept) the agency is staffed by people who are knowledgeable about aviation, and are better equipped to make smarter aviation related decisions.
For Congress to override the FAA you'd need some majority, in both houses, willing to make a technical decision which is directly related to airplane safety. That would require enormous amounts of time to educate Congress people, time which Congress has no interest in providing.
They created the FAA specifically to remove all aviation issues from their docket. They are not now going to medle with this one issue - that's not how the system works.
Obviously, like all good govt beaurocracies the FAA has grown big and slow and cautious and so everything takes forever. They are pretty much incentivized to keep kicking the can down the road, it is quite literally their business model.
Ok, but, they have actually gotten directly involved in aviation matters in very specific terms, and they do so regularly. This isn't theoretical and I'm not hypothesizing; they've actually done it, a lot. Usually it's to tell Aeromedical to knock it off (a famously dysfunctional division), and a few years ago Congress ordered the FAA to make a whole separate medical track that routes around the FAA almost completely. So it wouldn't surprise me at all to see them step in here. You'd be surprised how many people in Congress are pilots and are quite happy to tell the FAA where to stick it.
"But the applicant, in this case GAMI, should have a right to know who is on the TAB and what their credentials are."
Hmm. Seems like 737 MAX was about the incestuous relationship between the FAA and Boeing, at least in part. Perhaps when there is less knowledge available about the people responsible for approving things we stand a chance of a meaningful result.
I wonder how hard it would be to adapt a plane to run on propane? You'd need to find somewhere to keep a cylindrical tank (so not the wings) and ideally you'd need a liquid-cooled engine so the coolant could heat the gas vapouriser. You'd get 115 octane fuel, and no CO / HC / NOx / SOx or other nasties in the exhaust, just CO2 and water.
I figure that finding somewhere to mount the tank would be a pain in the arse. Maintenance is far easier than with petrol systems because it's not constantly trying to set you on fire.
Umm, Propane is constantly trying to set you on fire, in fact harder than gasoline and kerosene, because by default when it escapes it's going to switch to gas phase and, being heavier than air, will pool instead of nicely getting away, making it much worse explosion danger than AVGAS or Jet-A1/Diesel.
Any leaks in unventilated space create risk of fuel-air explosion. Moreover, even comparatively "low" pressure systems where propane/lpg is used in gas form have pressure considerably higher than atmospheric and from the point of dangers and maintenance issues are a high pressure system just waiting to create a nice FAE lightshow. High efficiency liquid injection systems would be even funnier (FSVO).
With the default state of propane being gas, and 5%-20% mix being apparently sweet spot for explosion, you're probably going to have to redesign everywhere that fuel lines go with an eye for propane vapours. Not fun at all.
Not really, no. You just run the propane lines roughly where the petrol lines run.
They run at very very low pressures - in the tank it's less than about ten bar, usually eight or so. The fuel rail pressure in a modern petrol injection engine is far higher, and when you get into DI engines as you say they become hilariously high pressure.
There's not really any drama when you want to maintain it - if you want to disconnect a fuel line, you just close off the tank valve, run the engine until it cuts out from fuel starvation, and the line is more or less empty. You probably blast more HC into the air when you spray your deodorant in the morning ;-)
Given how oldschool aero engines are, I would think a suitable gas conversion would be a single-point mixer and vapouriser like on my old Range Rover (similar level of technology - massive low-compression overhead valve boat anchor). The only thing is you would need a liquid-cooled engine to get a coolant loop to feed around the vapouriser, or you'd need to come up with some other clever solution. Aircooled industrial engines running on gas used to just heat the vapouriser directly with the exhaust, but you're not allowed to do that any more!
There's still a problem that running the engine till fuel starvation is not exactly a practical option, but then arguably you could make it so that standard shut down depended on at-tank cut off valve (going to make certification a PITA). And of course you can't reuse original fuel runs because for majority of aircraft, the tank won't fit where existing tanks are.
I'm still unconvinced that you could avoid considerable reconstruction of the fuel lines - there are reasons why propane/LPG have different hazard classification, and what is easily allowed on a ground vehicle can be a big nope in an airplane.
On the more practical side, it would be dead in the water from legal issues - you'd have to recertify the plane, possibly deal with the fact that there's AFAIK no preexisting baseline for certification, and unlike 100UL you'd also add pilot & mechanic retraining - at this point you might have better ROI by shooting for the stars and going the cryogenic hydrogen route. While there are some CNG & LPG conversions around, pretty much everything seems to fall under experimental classification - something wildly different from the goal of getting G100UL declared fully equivalent to AVGAS 100LL, which would allow everyone to just switch supply.
Well in an automotive install you'd have a shutoff valve at the tank multivalve that you can physically screw shut, and a solenoid valve to allow fuel out to the line. Then up front there will be a filter and safety valve with another solenoid valve, and finally a solenoid on the vapouriser too. If I want to take a vapouriser off I'd just unplug the solenoid for the safety valve, start the engine, let it cut out, and then unscrew the pipe. Similarly if I wanted to work on the safety valve, I'd shut the tank off and let it empty the line running to the back of the car.
The gas lines we use now are thin nylon with a tough PVC jacket over them, about as thick as a pencil (6mm inside bore) and flexible enough to tie your boots with ;-) It's a long way from stiff fragile copper line.
Physically? A lot harder than converting it to unleaded gasoline. For one, existing aircraft are designed around storing the heavy fuel near the center of lift/mass. (One benefit, the aircraft keeps its trim as the fuel is burned.) This video by Real Engineering [0] is a great overview. You could fit a propane cylinder into the tail of a Cessna 172, but now there's a lot more weight aft, the aircraft might be difficult to trim and exhibit unsafe handling characteristics. This same packaging issue exists with hydrogen-powered aircraft. Retrofitting is infeasible, lifting body designs are one possible solution.
Administratively, getting the FAA to certify it? Hahahahahaha.
Not just a cylindrical tank. A pressure vessel. Anything that can store propane is going to weigh a lot more than a rubber bladder in the metal the plane is already made of.
Not even a rubber bladder in many cases; there are plenty of places in wings, fuselages, and empennage that make for great fuel tanks if they're just sealed up. Wet wings are quite common.
Have you seen the payload numbers for light aircraft? Payload with full fuel on a Cessna 172 is only 369lb. How much does a vessel that can withstand 10 bar weigh? A light truck tire weighs about 50lb. Recall that this vessel must withstand the temperature, pressure, and vibration extremes of aircraft application. Light truck tires aren't typically filled with flammable gasses.
10bar is a terrifying amount of pressure when it comes in your direction.
Not sure, to be honest. I can lift the 95 litre tank in my Range Rover with one hand, so probably about 20-30kg? When it's full there's about 40kg of gas in, so that's very much a two-man lift. But bear in mind that's something like 6mm steel and intended to be literally indestructible. The dinky fibreglass gas bottles you get for patio heaters and forklifts are about 5kg and take an 11kg fill, which isn't a lot.
10 bar is not much more than the pressure in your car tyre, and roughly same as the average road bike tyre (currently running about 12 in my road bike). If you disconnect a 10 bar compressed air line, it hisses a bit. If you disconnect a 10 bar LPG line you get a lot of very cold gas on your hand, and it'll take ages to get the mercaptan-y smell off you.
1bar is 14.5psi. Are we doing the same conversion?
10 bar is literally 4x the pressure in my car tire and 50% over that of my road bicycle. My air compressor operates at around 10 bar but the hose is regulated down to 2.5 bar and blasts debris all over the driveway when I disconnect it. If I don't firmly hold the air tool it shoots out like a missile.
30 extra kg is a loss of about 20% of effective payload. And this says nothing of the loss in power density.
The option of using an aero- Diesel engine to be able to run from Jet-A1, which is plentiful at many airports seems to be a good approach, and far preferable to having a heavy, bulky pressure vessel onboard.
Do you have a reference for lower NOx emissions from propane? My understanding is that most NOx is a product of combustion in air (although it can come from impurities in the fuel).
As for SOx, natural gas can contain H2S which produces these, is it normally significantly less for propane?
There's no H2S in propane, although there's a little methyl mercaptan in it as an odourant so it "smells of gas". As for the NOx emissions I'm not sure why it's lower as in theory it should burn hotter - LPG runs lean which is why there's no CO, but that should make more NOx.
The whole point of this decades-long unleaded AVGAS saga is to develop a fuel that is a drop-in replacement for the current leaded AVGAS. A fuel that needs to be stored either in a pressure tank or chilled does not fulfill that requirement.
Now, if you're developing a new plane from scratch, I guess propane in theory could be an option. But why? For aircraft, energy density of the fuel is important, and propane does pretty well here, slightly better in fact than gasoline or kerosene (jet fuel). But in practice more than offset by the requirement to store the fuel pressurized. And then you have the whole fuel infrastructure issue, how are you gonna convince airports to stock propane considering they're already struggling to find an economic case for AVGAS due to the long-term decline of general aviation.
I think if you're going to develop a new plane, it would make sense to make it use the fuel that's available, namely Jet A1 (well, maybe electric for some usecases). Sure, it's not usable in an Otto engine, but since you're developing a new plane anyway, power it by a diesel engine or turbine.
Yes, and indeed in the mid-to-late 90s a lot of manufacturers experimented with Peugeot XUD engines in aircraft - various Merc ones too, but they were a bit too "high precision" for aircraft use and rattly old Citroën BX diesels were about perfect :-)
Currently some of the most widely used diesel aviation engines, the Thielert/Technify/Continental 1.7/2.0 liter one, as well as the Austro E4, are both based on a Mercedes car engine.
I definitely do not want lead in any emissions but this has to be a pretty small contributor. Plus airplanes I imagine are going to spread that lead over a much larger area vs inhaling car fumes. Has to be pretty low on their list of things they need to do.
That being said I would one day like to get my pilots license and mess around a bit with flying - so common people - lets get this show on the road! ....or air?
Unfortunately lead in fuel is used as an excuse to shut down airports. Lead, noise, "safety..." all the red herrings used by local politicans and the developers who own them, along with small-time (or big-time) land speculators to call for airport closures.
The fact remains that unless piston planes can run on ACTUAL car gas (which means gasohol) in the foreseeable future, GA is probably doomed. Or we can stop putting methanol in gas... which is also an excellent idea.
The implication is that leaded gas will eventually be outlawed. It's also significantly more expensive and as such is putting pressure on an already expensive market.
That's like asking why the gas-fired-appliance industry is doomed if natural gas is outlawed. Piston GA has been running on leaded gas, and the unleaded aviation gas that exists is only certified for something like 35% of the piston fleet.
But that's not the only major problem. GA suffers from a shrinking pilot population, with cost being a huge hurdle for both training and operation of planes. Replacing one niche fuel with another isn't going to help.
The industry should've tackled this issue decades ago. The writing was on the wall for leaded gas in the '70s. Yes, it is a technical challenge, but after this much time I find it hard to believe it wouldn't have been solved with enough motivation and a regulatory regime that fostered a solution.
> Unfortunately lead in fuel is used as an excuse to shut down airports. Lead, noise, "safety..." all the red herrings used by local politicans and the developers who own them, along with small-time (or big-time) land speculators to call for airport closures.
What should we presume these are red herrings? Lead and noise aren't problems? Another commenter posted research indicating that the lead is a real problem.
They are red herrings because the airports in question are invariably LESS noisy and LESS polluting than they were when the fake NIMBYs willingly moved next door to them. This is through decline in the number of operations and the technological advancement of the planes themselves. Compare the noise and pollution of a radial-engined plane to that of a modern fuel-injected plane with electronic ignition.
The "safety" hysteria is easily debunked when you compare aviation accidents near a given airport with the automotive accidents on ONE major street nearby. Santa Monica is another example here, with not one neighbor of the airport killed by a plane crash in a century... while car crashes on the street adjacent to the airport kill (on average) a person every year. Yet this airport will likely be shut down and destroyed after an illegal (Brown Act-violating) back-room deal was struck between an outgoing FAA administrator and the SM city council.
Another favorite lying tactic is to cite, for example, "11 crashes in the last 12 years at such-and-such and airport," but when you look at the accidents you find that they were nowhere near the airport; they're falsely cited because the plane LEFT from that airport or was headed there. That's like shutting down O'Hare because a plane from there crashed in Iowa.
And as noted, iconic Meigs Field, which sat on an island posing zero threat or even annoyance to anyone in Chicago, was destroyed at 3 a.m. by Mayor Daley. This asshole had city fire trucks aim their spotlights at the webcam on the field to hide what he was doing. And what was he doing? Stealing an irreplaceable resource from taxpayers because downstate IL politicians used it... and he didn't like them. But his excuse to the public (three years after 9/11) was that he'd heard that people were worried about a small plane crashing into a building.
This is the kind of corrupt trash arrayed against our thousands of public-use airports across the country, just when aviation advancements have picked up speed and the light-aircraft industry has attracted large amounts of investment and attention. Not to mention the rest of the trash: local politicians taking payoffs from developers and pandering to land speculators.
Nobody wants lead. But lead is going away. We didn't dismantle the interstate highway system to get rid of it from cars, so we sure as hell shouldn't dismantle our national aviation system to get rid of it from planes.
True but leaded fuel for cars has been eliminated years ago. So this is now a major remaining source of environmental lead especially around small airports.
I used to fly 172s and I worried about inhaling the lead fumes and getting sprayed with it during the fuel drain checks. Lead exposure is cumulative and can lead to serious neurological problems later in life. And I've already had a fair share with my electronics hobby (soldering)
I know this from experience that when we switched from leaded to unleaded gas in the 70’s for a fleet of 50 cars, it caused spark plug fowling in every one of them due to flakes of carbon coming off piston heads. I don’t think you want spark plug fowling at 12,000 feet.
Airplane spark plugs foul constantly, primarily because of the large amount of lead in avgas. Many airplane engines (e.g., Lycoming O-360) are already approved to run on unleaded fuel and have done so for years with vastly improved plug fouling. Additionally, spark ignition engines have redundant plugs (actually, entire ignition systems) to reduce the effect of this issue.
reply