It’s a better starting point than auto engines. Auto engines are not designed to run endlessly at 75% power settings.
I have four of these engines in my garage. There is zero chance they would make good aircraft engines. They make their power at 9000 RPM and above. If you could stand the noise–which you couldn’t–they wouldn’t last long at the 70 percent duty cycle of aircraft engines.
Don’t forget Rotax tried this with a sophisticated V-6 14 years ago. They abandoned it as untenable. But it could have worked with more development dollars and time. If sorted out, it would have been a lovely engine.
And all the people here complaining about 100LL and pining for new technology wouldn’t have bought it. Which Rotax fully understood.
Since it happened before my time in this business, I wondered what was done to allow some of the big radial powered airplanes that used what was 115/145 octane avgas that was colored purple, when 100LL was introduced? I talked with many persons who were in the military during the 50’s and 60’s who used to work with that fuel. Another suggestion about adapting high powered or turbo-charged may not be workable. Most light twins have marginal single engine climb capability and any reduction in power would result in no single engine climb at all. That would put most pt135 outfits out of business flying those planes. Switching to turbine (using jetA) would not be cheap either. I find it highly unlikely any privately owned ( not government) flight school could afford or actually make a profit on airplanes costing millions of dollars apiece (verses thousands). As far as the constitutional (5th amendment) requirement to compensate those for the government “taking” of airplanes due to leaded fuels being banned, all one has to do is look what has happened to all those businesses lost due to all of the COVID shutdowns and restrictions. As far as I know none of them have been compensated!
Personally I think the only really tenable way ahead for a long term solution is for Continental and Lycoming to create as close to possible a drop in diesel replacement engine for the turbo 520 and 540 series engines. Yes there will be an initial wrenching switch over but 100 octane days are done. When not if, 100LL is euthanized by government fiat or a supply chain failure, I don’t believe there will be any viable affordable replacement and the small and decreasing volume of 100 LL pumped just is not there to interest the deep pockets who could put the kind of resources to solve the problem of how to get 100 Octane without the lead.
94UL is a proven existing solution for the smaller engines but Jet A is the future for GA high performance piston engines
ALL of those business shutdowns have been ordered by state and local governments. Not by the feds.
And who will author the hundreds - if not thousands - of type-specific STCs that will be required, to allow these new engines to be installed in airframes? Details.
The fourteenth amendment makes the constitution apply to the states as it applies to the feds.
How many turbo charged airplanes are viable right now ? Whole swaths of old turbo 310, 320,early 340’s, 401/402, tip tank 414, 421A/B, turbo Aztec’s, early turbo 210, turbo Lances, and high time short body Navajo’s have a sell price less than the cost of the overhaul of their engines. They are going away regardless of the future of 100LL
When you look at airframes where it is worth spending 60K for an overhaul of the existing turbo big block Continental/Lycoming, the list shrinks substantially. I bet 25 STC’s would cover 90 % of the types which are viable going forward
I want to agree with you guys, but I’m not willing to give up. Besides, I’m not sure they have to do anything at the rate GA is dying, the butchers just have to wait for the beast they’ve cut to bleed out.
Continental owns the SMH turbo diesel now IIRC. It will work in a 182 or a Cirrus. It’s been done.
Unfortunately, too heavy for some others because of balance issues.
David,
I’m not sure what’s up in the present market, but that was true of many of those models back when I was still selling planes over a decade ago.
Many comments about auto engines seem to ignore that the three (?) Jet A pistons on the market now are all based on auto engines. Just Say’n.
If it’s true that innovation is being thwarted by certification, would allowing owners to convert their planes to a new class of experimental use be a solution? If the government won’t make compensation, then it seems it should at least make allowances. Changes to the liability situation and/or regulatory regime would likely result in solutions.
Also, I’d really like to hear a reaction to my earlier suggestion that we put an end date on letting new 100LL planes get sold. This is just adding to the problem.
The Continental TSIO 550, is certified for 94UL. Virtually all of the IO 520 and IO 540’s will run on 94UL with low compression pistons, a 5 K mod. Yes there is a modest loss of power but in exchange you have fuel certainty for forever.
Instead of burying our head in the sands how about the alphabet groups lobby for a set in stone drop dead date on 100LL. If we said to everyone that only 94UL will be available as of Jan 1 2024, then everyone can plan accordingly and you have neutered the environmentalist.
That modest loss of power may not be acceptable for a twin engine plane due to loss of any single engine climb performance. A lot of the older airframes that are still flying in Pt135 and pt 91 are there because the manufacturers have not produced a replacement for the jobs those airplanes do, or the ones that have been are too expensive to buy or to make a profit with. I do agree with the proposal to stop certifying new airplanes running on 100LL. It would be a good place to start with the final phaseout of leaded fuels.
For years a couple of engineer brothers from Toulouse developed an aero version of the Suzuki Bandit motor, built from the 1980s for 20 years or so – it used spay oil cooling.
They had some success with European microlights – with a built in reduction gearbox and manual clutch, it did not weigh much more than a Rotax, and had advantages of electronic injection, was quieter and smoother etc.
But no-one is going to make much of a profit with microlights and when they tried to develop a 150hp model for small Cessnas and the like they were swamped by paperwork and gave up.
Similarly lots of BMW boxer engines in microlights, at the 100 HP mark with dual ignition, fuel injection, et al, go well, sip fuel and are unbreakable, but difficult to go above 100 HP with them.
The South Africans linked with the Slinger (?) were developing a V6 related to the old Ford V6 Essex engines, 3 litres, very reliable and updateable, but last I heard they were also mired in the paper work bog.
Read all these noteworthy comments, but one issue that nobody seems to ever talk about is fuel stability. The octane can be there, sure, but will it be there next month? Avgas is, what, mil spec’d for two years? Auto fuel goes south in a month. Yes, my airplane will run on mogas, but if it sits out the winter, it best be drained! As far as auto engines are concerned, there are three local “experimenters” that had belt reduction auto engines which all have experienced at least one crankshaft failure. Anecdotal. yes, but I won’t try that in my airplane, thank you.
I looked at the SMA turbodiesel having run a TDI in my VW Passat (only part of that car that worked well). I really liked the idea and when it came time to overhaul the O-470R, I looked long and hard at OSH. When the STC installed price came in at more than $70,000 (roughly twice what I paid for the airplane and 4 times the cost of a new limit overhaul), the engine was overhauled. Another issue, at least then was there was talk of a service ceiling limit of around 10k, which didn’t give me enough clearance to get over even the lower passes where I fly and certainly not enough to get in/out of high altitude fields I use, including LXV.
The mogas STC lives on, and I cart gas to the airport, or land at airports that have mogas all the while badgering my local FBO to give us mogas.
I’d be happy with a compression fired engine, if the power-weight ration works for the airframe.
I’m not so sure this is true. Mogas with 10% and above ETOH is certainly unstable. Shelf life of alcohol laced fuel, is similar to that of an alcohol laced pilot…very very short, less than a month or so. It’s worse when stored in airplanes. gaskets expand, fuel hoses leak, water/etoh extraction corrodes. Not a pretty picture at all.
ETOH free mogas has a shelf life of about 6 months to 18 months under appropriate storage conditions. It’s not clear how fuel leads to a crankshaft failure as there should not be much fuel in the crank case, and what is there should be evaporated off as soon as the oil comes up to temperature. More likely, the load on the crank shaft and duty cycle on those engines are the culprits. I don’t think I’d put an automotive engine in my airplane either.
Avgas is usually stable under appropriate storage conditions for about a year, so there isn’t much difference between ETOH free fuel of one or the other stocks.
As for storage, I believe Cessna has three levels of storage for a/c, flyable, temporary, and long term. Short term is pretty standard, fill the tanks, turn off the switches, tie it down, Fly it for half an hour every 30 days. Amazingly the CSL says if you can’t fly it ground run it for 30 minutes…now I know where that old saying came from…not recommended these days, I think. For long storage, take the plugs out, spray the cyls with anti-corrosion stuff and put the plugs back. Fog the engine compartment through the oil filler, put desicators in the plug holes, exhaust and breather and tape things shut.
None of these procedures suggest draining the fuel out of the airplanes for the winter. This was written before the hairbrained idea of putting ETOH in fuel came about, so if there’s alcohol in the fuel I’d drain it. I use ETOH free mogas in my farm equipment and it makes the winter just fine with similar preservatives.
I know of only one person with elevated blood levels of lead- he worked in a 50 y.o. lab doing gold assays. Do you know anyone with lead poisoning?
It is a non-problem with zealots looking for a solution.
The cost of a new synthetic fuel will be three or four times as expensive as our current low lead fuels.
I doubt it. Even with new bladders (IF the old ones won’t work), fuel lines, possibly injectors, etc., especially if the FAA paves the approval path for such things. The engine proper will need nothing, and will likely now last longer.
Still, a fuel that doesn’t require mods would be better, but I’m old enough to remember when the vast majority of airports had two grades of piston fuel. Heck, many airports have two or three tankers, and some have split tankers. Or just have a “lead blender” to mix with the other stuff, for planes that must have it, until a solution (that doesn’t involve the demise of GA high-performance piston engines) is reached.