Cubdriver

It's expensive and troublesome adapting car engines to aviation even ignoring the certification cost. Problems are operating altitudes, heat and cooling, loading differences, RPM, fitting the engine inside a cowling, making it compatible with a variety of existing aviation components (vacuum pumps) and so on. It's a lot of things to work out. It adds up.

As far as certification is concerned, people do not realize what is involved with the costs a company must pay if it wants an engine to be certified for aviation beyond experimental and light sport segments. Part of it is FAA lab charges to put the engine on a stand and a few airframes to show it works as advertised. But what people do not realize is that every single part in the engine must also go through an applicable certification process. These costs are placed well upstream of the engine manufacturer in most cases. Such costs reflect the expense of keeping an elaborate paper trail showing extensive details on raw manufacturing stock, finished component testing, adherence to standard for equipment used in manufacturing, and all associated costs such as maintaining records for decades. Aerospace manufacturing is replete with manufacturing controls, tests, paperwork, and regulations not found in automotive manufacturing. This is one of the reasons things change so slowly in the aerospace industry, and are the reason general aviation moves so slowly.

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Continental Motors Reveals Jet-A-Burning Piston Slapper

FLYING eNewsletter (5/20/10) Teledyne Continental Motors (TCM) has unveiled a two-engine project that will bring jet fuel to the light-aircraft industry. The first, a 230-hp four-cylinder engine is expected to be certified next year. A follow-on six-cylinder, 350-hp version could follow as soon as two years later. TCM said the engine program stems from acquired technology — but would not identify which European company the already certified engine technology came from. (According to an article on AvWeb, the TCM engine bears a striking resemblance to the SMA SR305.) Under the license agreement with the original maker, TCM now has free rein to further develop the existing engine as it sees fit. The company has said it expects the new engines to cost not much more than their gasoline-burning counterparts in the same power range. TCM's version is currently undergoing tests on a static test stand and in flight on a Cessna 182 Skylane. Specific fuel consumption (sfc) of the new engines is said to be in the .36 range.

Kerosene Engine Certified in Europe

(AOPA ePilot, Alton K. Marsh, 5/28) Centurion has received a supplemental type certificate (STC) for the installation of the 155 horsepower Centurion 2.0s kerosene-fueled, piston engine in the Cessna 172. The European Aviation Safety Agency (EASA) issued the STC to Centurion, the subsequent sales company to the insolvent Thielert Aircraft Engines GmbH. Cessna models 172F to S can now use the engine. First deliveries begin in June. Certification is expected soon for the Robin DR400 Ecoflyer and Diamond DA40 TDI. The Centurion 2.0s is the more powerful version of the well-established Centurion 2.0. With an identical weight, it generates an additional 20 hp. “Everyone who was impressed by the flight performance of the Cessna 172 with the Centurion 2.0 will be enthusiastic about the Centurion 2.0s,” said Centurion CEO Jasper M. Wolffson. With the Cessna 172S model, the new engine increases the maximum takeoff weight limit from 2,450 pounds to 2,550 pounds. Cruising flight fuel consumption is 6.4 gph at a speed of 115 KTAS (at 70 percent power, 6,000 feet). The takeoff distance over a 50-foot obstacle using the Centurion engine is 1,617 feet. The range with the 44.5 gallon standard tank is 665 nautical miles.

Cubdriver

Lycoming and Continental Differ on 100LL Replacement

(FLYING eNewsletter, 6/09) According to a story posted on Avweb, Lycoming has gone on record opposing the development of 94UL as a replacement for 100 low lead (100LL) aviation gasoline. Continental supports development of 94UL, and is currently experimenting with modifications to its engines to accommodate the lower octane level — approximately 8 octane points less than leaded fuel. Both engine manufacturers acknowledge that many of their engines will perform satisfactorily on 94UL, but the higher-power, higher-compression engines are problematic. Computerized ignition (IE2 from Lycoming; Powerlink from Continental), knock-sensing technology and in some cases, lower-compression engine overhauls are among the fixes proposed to bring older engines into line with reduced octane levels. But Lycoming warns that the drop in fuel octane cannot be made up without potentially serious impact on engine performance. Lycoming believes that 100-octane lead-free aviation fuel is an attainable goal and should be pursued.

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AOPA Videocast

AOPA Videocast: Issues with Leaded Avgas


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Notes on Above VideoCast: Issues with Avgas.

Why do we need to replace 100LL?

-30% of the piston fleet need high octane fuel to prevent engine knock and detonation
-that 30% actually uses 70% of the avgas consumed
-many commercial piston aircraft like the DC-3/4/6 series need higher-octane fuel
-70% of the fleet may not need it, but it is not practical to have two fuel grades
-EPA demands it for the environment (lead is a proven carcinogen)

What does a suitable replacement for 100LL need to do?

-have good cold and hot start behaviors
-have similar weight to 100LL
-be affordable
-have good freezing point
-have stability over time
-not leave post-burn deposits
-provide octane sufficient to prevent detonation
-be cheaply and easily manufactured
-be transportable
-be environmentally friendly

How soon is an avgas replacement coming?

-it is too early to make a decision now (ie. Swift, UL94, engine modifications, etc.)
-the solution may not include only a fuel swap; it may include engine modifications to reduce detonation
-when all issues (economic, technical, and certification) are answered
-FAA has the final say

What are some problems with going to a new avgas?

-avgas refiners refuse to make more than one grade of avgas, because the volume is small. Shipping, refining, and tanking all costs money and avgas represents only around 0.5% of all transportation fuel sales.

Cubdriver

Here's an opinion piece from AvWeb that speaks to the same issues we have been knocking around here in this thread. Namely, why are small airplane engines so backwards technologically, and why not drop car engines into piston airplanes and get all the advantages accruing a modern car engine. He basically says the same things I say on this subject. 1) The economics of new engine development do not justify the investment, and 2) it has already been tried and it repeatedly fails.

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Fuel crisis: What We Really Need Is...

(Paul Bertorelli/ AvWeb 6/17/10) The companies that build aircraft engines—and for the purposes of this discussion, let's call them Continental and Lycoming—are staffed by the dumbest people on the planet. This would be the general gist of opinions of pilots who know automotive technology and who also own or fly airplanes. To them, the ongoing discussion about finding a replacement for 100LL is simply a failure on the part of the Big Two to freely adapt the advanced engine technology that's out there for the taking. There are various reasons why these companies haven't done this, but for us experts sitting on the sidelines, the general thinking seems to be that they could do this. They just have chosen not to. The reality is different. And it's not a question of understanding and adapting technology because the automotive engineers who can do this work are readily available. Some of them even work at Continental and Lycoming. Some are pilots, too. The challenge is to find enough buyers to actually construct a business plan that won't crater within, say, five years. This is another way saying buyers say they want one thing, but when presented with that very thing, they demure...

TonyWilliams

So, what I gather from Paul's article is that the technology isn't bad in cars, or not adaptable, but just not economically viable.

I'd agree. Because the hoops to jump through would be HUGE to certify such an engine, even though the "certified" ones have any number of HUGE problems.

Look at the AD lists for some of these. Look at the SDR's, and all the parts that are sold to repair these engines. Swapping "jugs" on piston aircraft is almost sport on some models. Dropping valves, breaking crankshafts, grinding of cam lobes, oil pumps that sheer off and quit, cracked crankcases, mechanical magnetos failing in any number of ways, cracked exhausts burning the wing off (admittedly rarely part of the engine package, but instead the airframe mfg "engineers" these). And I'm just touching the surface of all the "features" of these FAA certified masterpieces.

I agree that the decades of advancements in the piston engine world (not just cars, for sure) would be difficult to economically bring to the piston aircraft world.

Not technical... economic. And the single largest cost might just be the certification effort that motorcycles, boats, cars, trucks, lawn mowers, farm equipment, etc, don't have to engage.

And please have Paul answer this question; if the conversion of automotive engines "can't" be done for whatever reason, why is it being successfully done now with Mercedes Benz diesel engines?

Cubdriver

Right, he didn't say it can't be done it's just that for various reasons it isn't economically viable. Right off hand, I do not know how Diamond managed to work the numbers on their Benz diesel conversion because they obviously do not sell more than a few hundred DA-40's with those diesels per year. I cannot imagine it is paying for itself. I suspect they are losing money so they can keep existing airplanes in the fleet going and retain customers. If you know otherwise, I am all ears. They are not going to show the balance sheet anyway, so we will never know. But one thing is for certain- multiple attempts to put automotive engines in airplanes have transpired and they never really work because of FAA certification costs and the overall poor payback on the deal.

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Cirrus Prez Comes Out Against 94UL

(Brent Wouters, 06/17/10 Cirrus Aircraft) Cirrus Aircraft Community, Recently there has been much industry discussion regarding the future of 100LL aviation gasoline, the likely transition to an unleaded aviation fuel in the future and the possible impacts to owners, operators and general aviation industry health of a future fuel. While this subject is by no means a new issue, the recent Environmental Protection Agency (EPA) issuance of an Advance Notice of Proposed Rulemaking (ANPR) regarding lead content in aviation fuel formally initiates a regulatory decision-making process and has increased awareness of this topic and its potential future impacts. Cirrus has been actively working on this fuel issue for many years now and we are integrally involved in the industry leadership team working with the EPA, the FAA, and avgas producers. Simply, we are aggressively focused to achieve the very best path ahead and Cirrus will ensure that this path will keep your aircraft flying with the minimum possible transition and operating costs...

rickair7777

My understanding from the engine industry perspective (I used to do LARGE engines) is that the cost is not so much FAA certification. The FAA exists to advocate as well as regulate aviation, and a lot of local FSDO jobs will be N/A if GA continues it's gradual decline. They do not have an incentive to be obstinate and kill the golden goose.

The actual hurdle is the technical development cost for a clean-slate engine. This is very high for a modern engine design, and the potential ROE would be too low for a GA engine unless you take a VERY long term view like 30+ years. Unfortunately modern managers are only interested in next quarter's stock options, and are not likely to look further than 3 years out...they won't be around to reap the long-term benefits.

An automotive conversion offers a few advantages...the basic nuts-and-bolts level engineering and testing is already done, and you have an extensive operational history to build from. All you have to do is add a few aviation specific tweaks, and off you go. The downside is that the engine was not optimized for aviation originally, and without massive re-engineering, probably never will be as efficient as a clean-slate design.

Also your options are probably limited to a tiny handful of auto engines which just happen to have a design close enough to you need for an airplane. And if the OEM stops making the engine, the aviation demand will not be high enough to sustain production, at least at an economical cost. You could easily end up starting all over if your source auto engine becomes unavailable.

TonyWilliams

I don't know if the engines turn a profit, or not. But, it is being done, "successfully". Maybe they are losing their butts on this... if so, why not just use the Lycoming engines that they already have certified?

Quote:

Cirrus Prez Comes Out Against 94UL

I didn't see anywhere in the article where they were against 94UL.

TonyWilliams

Many very popular engine designs are produced and can be purchase wholly, or in parts, from outside vendors.

Volkswagen, Chevrolet and even Lycoming engines are a few examples. I doubt you can do the same with a Mercedes diesel, but that doesn't prevent a company from "cloning" the design after if has become obsolete for MB.

Buy it "cheap" now, get the certification, then over the years, piece by piece, reproduce all the various parts, waiting for the day that MB pulls the plug.

Then reproduce the thing for the next 50 years, like Cont / Lyc do !!!!

Cubdriver

Rick- thoughtful comments as usual.

Tony-

94UL is 100LL Avgas, without the lead for octane boost. The lead additive is there against detonation, it boosts the octane to 100 so the engine doesn't kill itself. Bear in mind Cirrus sells only high-octane piston engines, they have a lot of skin in the game, they know that 94UL no-lead is not going to work in their airplanes. Money and sales are at stake. Cirrus president calls a meeting with the top propulsion engineers and asks: I need an answer as to whether or not we are cool with 94UL ruining all our engines because now is the time to go public on it. The engineers say heck no, meeting over. He goes out on a limb the following day with:

Corporate presidents are for politics and photo ops. This statement is an early attempt by a vested interest to steer the government decision on which fuel will receive approval as a replacement for leaded aircraft gas. I favor a government subsidy for biofuel and I realize it is a dreadful solution. The loan payback would have to be spread out over many decades with an appropriate return on investment. Many do not believe government should be paying for things a free market economy should produce. The problem is, there is no free market-driven interest in the short term to protect the environment. When the EPA finally trumps the FAA on the issue of when the lead has to go and finally sets a deadline, which they are threatening to do now, I do not think the market will be able to respond agreeably to diminished airplane sales resulting from jacked airplane prices. It will have to be subsidized until the cost is spread such that the buying public can still buy an airplane that costs about as much as it does now.

TonyWilliams

I'm actually reasonably familiar with the fuel, and the principles promoting the fuel. Even spent a few dollars on some of their products in the past 20 years.


The principals promoting the 94UL would say otherwise. It works, and works well. Now, we're playing politics where science should prevail.



The 94UL solution does not require this. Biofuel is a whole 'nother animal !!!