TCM Buys a Diesel: Does This Make Sense?

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Behind the scenes video from the Mobile press meeting.

So now comes Teledyne Continental jumping on the diesel/Jet A bandwagon. It took my e-mail inbox about 10 minutes to load up with comments. What's Continental thinking? Have they made a terrible mistake? Why aren't they pursuing a simpler two-cycle design like the Deltahawk?

All legitimate questions, of course — and all unanswerable. One thing that is knowable — because Continental says as much — is that the company senses an inflection point on the disappearance of 100LL and believes the decision on a new fuel needs to be made sooner rather than later. Make no mistake: This represents a major realignment in Continental's business plan.

The diesel is just part of a range of solutions Continental has in mind. It simply wants to be ready, and that's just smart business. Rather than developing its own engine, Continental simply bought technology fully formed from SMA, which has been flogging away at diesel for longer than anyone else.

Setting aside why SMA doesn't want Continental to say where the technology came from — not sure why this is, but the French have their own way of doing things — does this decision make a lick of sense?

Yeah, it does. Despite its long time in grade, the SMA SR305 is the Rodney Dangerfield of aerodiesels. From what I can tell, users who have installed it are happy with both its performance and its reliability. I did an in-depth report on the engine in this video. There are some shortcomings, however, which Continental will have to address.

Video of an actual SMA conversion.

One, there just aren't enough of these engines out there to form an opinion based on large fleet usage. There are some conversions flying, and Maule has been selling them for a few years to a handful of owners. (Maule is mad at us and won't speak to us, so following up with them is a lost cause.) Well under 100 of the SR305s have been fielded. That's not much experience.

Second, the engine doesn't like cold weather. It seems to start okay, but it has issues with low power settings in flight and in-flight restarts. Cirrus tried the SMA engine a few years ago and shelved it as a result. Continental's Johnny Doo told us the company thinks it can solve this problem or it wouldn't have bought the technology. I'm no diesel expert, but this ought to be solvable. I mean, c'mon, this is 2010.

The deal has a couple of sweet spots. Most important, it's not a sales or co-branding arrangement, but licensed, turn-key technology. That means TCM can pick up the diesel ball at the 40-yard line, not back against its own goal. This is a big deal because with a proven foundation in place, Continental can concentrate limited R&D funds on improvements and on leveraging the four-cylinder into a more powerful six-cylinder diesel, which the market desperately needs. And remember, TCM sees time as a driver here and they don't think they have enough of it to re-invent the SMA wheel. They think — rightly — that the industry is dragging its butt on the 100LL conversion, and if others get caught short, Continental doesn't want to be one of them.

I can see a benefit for SMA, too, in that getting what could be a high-juice market push from TCM toward the OEM sector, SMA will get some cred. Why they don't want to ride that wave by keeping their name off the street on this deal is baffling, but it's consistent with what buyers have told us about SMA. They haven't really pushed sales of this engine. On the downside, they are also getting a very able competitor in the OEM market. Continental probably won't concentrate on conversions, so SMA may still have a market there.

Technically, the engine has some pros and cons. It's oil- and air-cooled, so there's no cooling radiator to fuss with, but the intercooling and oil plumbing is still complex. It's essentially single-lever and has power density that's comparable to Continental's gasoline engines and better than the Centurion and Austro designs. It's also smooth, and, being direct drive, there's no heavy and failure-prone gearbox. I've flown it several times, and it's a nice ride.

What I don't like as much is the old-school mechanical fuel distribution system. Yeah, it's electronically scheduled, but it doesn't have the pulsed common rail injectors of state-of-the-art diesel. Although the SMA approach may have a reliability advantage, the diesel world long ago evolved into pulsed electronic fuel injectors driven fully by FADECs. I don't know if TCM will get there with its engine, but I'd like to see them try. For market purposes, it may not matter. No one really knows.

The fuel specifics are good, at .36 BSFC. Continental's very best gas engines can run at .38 or .39, and although that doesn't sound like much of a Delta, over the life of the engine it adds up to very big savings. That's attractive for U.S. buyers on fuel prices alone. For some foreign buyers in countries where avgas isn't available, it's a deal sealer.

The fuzzy warm part of this development is that a major engine company has finally chased the diesel train out of the station and gotten on board. That will help convince the diesel Luddites once and for all that resistance is futile.

Bottom line: This is a perfectly rational business decision with some strong pros, a few cons and moderate risk. It meets TCM's design brief for time to market.

Continental has in place an entirely new management team. These guys don't have any choice but to reinvent the company and now we get to sit back and see if they can do it.

To that, I say "bravo."

Comments (52)

The SMA is a real fantastic engine in performance and reliability. Unfortunately a very high cost to convert an existing airplane (about 100.000 Euro) such as a C 182 with such a diesel. At this cost there are no financiel benefits anymore, compared to the gasoiline engine, powered with avgas.

Posted by: ludo huybrechts | May 13, 2010 5:56 AM    Report this comment

I think TCM has almost a guaranteed market going Diesel - especially for 6 cylinder engines. The 4 cylinder market will be a little harder to crack in my opinion. I have some misgivings about the phase-out of Avgas - however the environmental movement appears to have much more clout than GA. When you look at the fuel specifics of turbine aircraft - even turboprops - I think there is still a need for piston twin aircraft in the C414/Piper Navajo line. A 300-350hp diesel would make these aircraft more viable. I don't know that I see these engines trickling down to the C172/PA28 series anytime soon, but these aircraft would be happy on the new 94UL that's being proposed. I know Thielert went there, but saving 3 gallons per hour in a 172 isn't so big of a deal. Now go from 45 gph to 30 in a medium twin and your corporate customers might be willing to drop the cash for the swap.

Posted by: Josh Johnson | May 13, 2010 6:36 AM    Report this comment

I think the future here for for TCM is in OEM sales and maybe experimental applications, NOT engine swaps on existing airplanes. SMA was not successful in this venue, having only secured Maule in the many years the engine has been available. My sympathies are with SMA, with the diesel OEM market effectively poisoned by Thielert and the miserable maintenance requirements required by that powerplant, not to mention the bankruptcy debacle.

TCM has already shown they are interested in the Light Sport marketplace with the O-200 Lightweight, so specialty markets are in their marketing plan. Homebuilders might have a chance with this engine. The WAM-100 and Delta Hawk have been very slow coming to market, and they won't have the traction in the OEM marketplace like TCM has, so they will have to be content with low volume homebuilder sales and military applications until the diesel wave lifts all boats, so to speak.

Offering the new Diesel to OEM builders for EXPORT sales where Avgas (in whatever form it is or will be) is unavailable, is an excellent start. This will also do much to prove the viability of the engine and the validity of the application.

Excellent point by the previous poster regarding the application in piston twins - those aircraft spend a lot of time in airports where Jet-A is easily available.

Posted by: TRACY SMITH | May 13, 2010 8:12 AM    Report this comment

I am a great fan of diesel technology, with a diesel pickup and a planned diesel BMW X5 purchase in the fall. I fly out west quite often and could use more power in my Bonanza but don't want the complexity and other issues of turbo normalizing. If a reliable 300 - 350 HP diesel with no weight penalty were available I'd buy it. This would allow me to a longer return on avionics investment, and fly a marvelous airplane (4th to last V35B) for many more years, and I doubt I'm the only one looking at this. With so many late model high performance singles and twins currently flying, this seems an extremely fertile market, but there has to be a performance as well as efficiency gain. But as Paul stated, it's unfortunate that it isn't a common rail design.

Posted by: Burns Moore | May 13, 2010 8:27 AM    Report this comment

Expanding on the economics issue touched upon by Huybrechts: At some point, possibly a year or two before the 100LL dries up, every north-american owner of an aircraft with an IO-520 normally aspirated engine or its equivalent will be facing a moment of truth. As a thought experiment, suppose that the average length of time that private owners keep an aircraft is 10 years. During that time they fly 1000 hours and consume 15,000 gallons of avgas. An engine change to a diesel will be $100K, the equivalent of an increase in price for the same amount of avgas of $7 per gallon. Maybe if the new UL avgas costs $5 more per gallon (assuming the it will be available) the incentive to put a new engine in my 30 or 40 year old C210 might still exist. On the other hand I get to fly it for a few years before making the jump to Jet-A, or not. More likely, a reformulated UL avgas might cost $2 to $3 more per gallon to buy, and as bad as that will be, I will decide that maybe fewer hours and no massive capital outlay is better than the switch. The sad reality is that without a viable UL avgas many of the aircraft with those big-bore engines are going to be parked, permanently wherever they are, UL avgas or not. I suspect that many of the owners facing what seem to be shaping up as a set of lousy choices will find other ways to spend their money. Suddenly boating looks good. Fuel OK, no TFR's, etc.

Posted by: David MacRae | May 13, 2010 9:06 AM    Report this comment

I wonder what the chances of a fire are when using Jet-A as opposed to avgas...in the event of a serious mishap? I also wonder why Continental is not pushing their new lightweight 0-200 (minus starter etc.) as a replacement for the A-65....I think the difference is weight is only 10-15 pounds while the power increase is 35 horsepower.

Posted by: Charles Elliot | May 13, 2010 10:08 AM    Report this comment

Its a pity TCM chose to simply buy somebody else's product when they have, sitting on their shelf since 1980, all the research for a far more interesting diesel engine design. These were 2-stroke radials, 4 and 6 cyl. configurations of 298Kw and 149Kw power. Unlike the SMA cost was actually a consideration in these design and they could be produced far more cheaply. BSFC was comparable to the the SMA and this was 19890 technology - no fancy electronic controls. There were areas of unproven technology, sure, but they have now been overcome with new materials like ceramics and carbon pistons. It makes interesting reading:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800011788_1980011788.pdf

Posted by: PETER THOMAS | May 13, 2010 11:54 AM    Report this comment

Mr. Thomas: Fascinating document, thank you. The answer to the question 'Why SMA" is found on page 69 of the document - the development time is 5 to 6 years for a flyable demonstrator engine. That appears to be much longer than TCM is willing to wait.

Also, why not build on the success of the SMA design while gaining valuable experience and continue development on the radial diesel? Is the SMA engine scalable for different displacements? Or is it a 1-trick pony? We don't really know, but this COULD be the start of something big, and TCM simply wanted to start NOW.

Posted by: TRACY SMITH | May 13, 2010 2:30 PM    Report this comment

I am a member of the Paramus Flying Club that was featured in Paul's SMA report. We have had great success with the conversion with an impressive dispatch rate. I do not understand this arrangement TCM and SMA has. One major reason the club decided to install the SMA engine was the consistent need to replace cylinders on the previous TCM engine. I just hope TCM gets it right. It seems to me that they cannot build good cylinders such as Lycoming. I hope it works out for the sake of future aviators. Diesel engines in airplanes seems like a prefect match. That is why we decided on our conversion and we are glad to see that TCM now believes so. The other issue it is a airplane engine from the get go, not a car engine modified. I own small equipment outfitted with Diesel engines and in 2800 hours of operation in 11 years the only thing it needed besides oil changes was the alternator bracket came loose and needed to be repaired.

Posted by: DAVID VILLANE | May 13, 2010 4:29 PM    Report this comment

As a 25 year diesel only owner and engineer, SMA made the right decision with traditional, mechanical fuel injection. I have shied away from any of the new, electronically controlled injection systems. $1000 fuel injectors with serious reliability problems is first and foremost. TO achieve direct injection on a diesel, you are talking about pressures starting at 1800 psi and going up from there. A solenoid mounted in an 300 degree environment, acting against those pressures is a serious challenge. I have a Mercedes 190D with over 500,000 miles on it with the original injectors. I would definitely fly behind an SMA, if the can solve the few problems. Personally, I am going electric.

Posted by: Ed Wahler | May 13, 2010 8:41 PM    Report this comment

About time this company innovated instead of living off the past.

Posted by: ROBERT M SHERIDAN | May 14, 2010 12:48 AM    Report this comment

Electric may make the most sense....todays dreams are tomorrow's reality.......and future shock is real.

Posted by: Charles Elliot | May 14, 2010 2:05 AM    Report this comment

"I think the future here for for TCM is in OEM sales and maybe experimental applications, NOT engine swaps on existing airplanes. SMA was not successful in this venue, having only secured Maule in the many years the engine has been available"

Tell me if I'm incorrect, but I think the SMA was STC'd for the Cessna 182.

Posted by: Josh Johnson | May 14, 2010 9:50 AM    Report this comment

Mr. Johnson:

I believe you are correct. Look how successful SMA has been with that marketing plan....have any 182 Cessnas come out of the factory with the SMA diesel hanging off the front?

It's all about numbers: since SMA couldn't get any traction with an engine with thier name on it, why not get some of that investment back through a licensing agreement and let TCM market and improve it? Seems like a win/win/win situation to me. SMA makes $$$, TCM makes $$$, the GA population wins with an alternative powerplant.....

Posted by: TRACY SMITH | May 14, 2010 10:36 AM    Report this comment

Okay, I think I misread your post. Makes sense to me now.

Another point - If there is ever a constant with aviation, it's that companies come and go with the seasons. I think what has hampered the SMA marketing plan is the fact that they are a startup - myself and I'm sure many others aren't willing to take a chance on a company that might be here today and gone tomorrow. Perhaps SMA is a very solid company, but we all thought Thielert was too. With TCM in the mix, we are at least reasonably assured of parts availability and support. I expect to see OEM sales as well as lots of retrofits.

Posted by: Josh Johnson | May 14, 2010 12:39 PM    Report this comment

Mr. Johnson: We agree. I can't imagine trying to buy parts for a Franklin.....if they are available they must be VERY expensive.........

Posted by: TRACY SMITH | May 14, 2010 12:52 PM    Report this comment

From the AvWeb story, "Continental is in a consortium pushing forward with eventual ASTM approval for 94UL, at least for Continental engines". As an owner-operator of an older Bonanza with an IO-520 engine, I'm one of the unlucky Continental owners that TCM is tossing under the bus. Who, besides TCM, is in that consortium?

There are high octane unleaded formulations that have been proposed, and all aircraft can use them without tens of thousands (and maybe many tens of thousands) of dollars of engine work. We need one of these fuels to be the 100LL replacement, and we are not being well served by TCM's desire to obsolete our engines by a regulatory change.

While the ideal new aircraft customer is made of money, most of us operating higher performance legacy aircraft are not. We use something like 75% of all the avgas sold, despite being a minority in number, because these are the transportation workhorses, used to actually fly somewhere.

I'm actually looking forward to an unleaded fuel, as the lead is nasty stuff for the environment, not to mention the deposits in our engines. But let's get a fuel everyone can use, otherwise, there will be a large number of previously valuable airplanes on the ground being parted out or rotting in place.

Posted by: Greg Goodknight | May 14, 2010 12:59 PM    Report this comment

Greg - hopefully I'm not igniting a firestorm with the comment I'm about to make. We're contemplating buying a light twin for our business so I'm aware of the potential cost of modifying a high horsepower engine. That being said, I'd rather spend 30k per side to modify each engine to be able to run on $5 94UL avgas, than do nothing and be running $9 a gallon Swift or GAMI fuel. I know, I know! this will ground aircraft, just like the prop AD's did on a whole bunch of Apaches, but at least the modified aircraft will stand a chance of being viable. When you look at replacement cost of your Bonanza, you can really spend quite a bit and it makes sense although I'm sure some will decide it costs too much and sell. People are lining up at the avionics shop to have the latest Garmin gee-whiz instruments installed for 30, 40, 50k, looks like we're all going to take this one under the cowling. I don't like it at all, but I'm afraid it might be reality.

Posted by: Josh Johnson | May 14, 2010 6:27 PM    Report this comment

I don't believe a gallon of G100UL or Swift fuel should be significantly more expensive than 100LL. Josh, I think you're being snookered into believing a massive replacement effort would be more economical

This isn't an issue of grounding a few older aircraft. This grounds every Beech Bonanza built since about 1960. Every Baron. Every Cirrus SR22. Probably most of the Cessna Columbia line, too. How long would it take to get all those engines rebuilt to use the new fuel? Currently, those engines are consuming about 75% of all the 100LL sold, so I'd say this has the potential to virtually wipe out GA.

If 94UL gets the nod, at the stroke of a pen many million$ of aircraft value will vanish overnight. More planes will probably rot on the ramp or get parted out than are rebuilt.

Posted by: Greg Goodknight | May 14, 2010 6:52 PM    Report this comment

think we have to be very careful and allow the competing fuels/technologies play out on the 94UL issue and not rush to an early decision. We are not hurt yet(100LL is still available), but if we jump to quick solution that turns out to be not supportable or economically inferior we will be. There are too many variables in the equation to solve now. It may be Geo. Braley, Swift fuel, FADEC/engine control solutions or we may have 100LL for the time to solve this. But most importantly let the free market solve for the best (in all it's various forms) solutions. If TCM or the EPA provides incentives, a 350 HP with lower fuel burn engine will be a marvelous deal come TBO.

Posted by: Burns Moore | May 14, 2010 7:04 PM    Report this comment

No, I don't believe it would be most economical to enter a massive replacement effort. Having 100LL available is most economical. After that, perhaps the 94UL is the least of the evils, and perhaps not. There have been rumors on this site that Swift Fuel will be around $10/gallon. The point I'm trying to make is that you can amortize 30k out of a Bonanza engine mod at $4 per gallon savings in about 400 hours. The old Bonanza guys that fly 20 hours a year I kind of feel for, but when you're buying and flying a late model Cirrus or Columbia, a 30k engine mod, if it even comes to that, would be about a year's insurance premium and an annual. The only point I'm trying to make is let's not stroke over the initial cost and then pay out 4 times the cost of FADEC over the life of an engine. Best solution is that Swift or GAMI comes out near the cost of 100LL. If that's not the case, it becomes very interesting. And, no, the fuel issue WILL NOT kill GA. But it will change it - perhaps radically.

Posted by: Josh Johnson | May 14, 2010 7:29 PM    Report this comment

Reality check, there are a lot more 20 hour a year Bonanzas than new SR22's with owners happy to spend a chunk of money to not be faster than an old 20 hour a year Bonanza. I'm one of those 100 hour a year Bonanza guys, and a $30K hit is about 20 years of my insurance.

We'd have turbines and Skyhawks and a whole lot less inbetween. I'd guess a big drop in fuel usage and many fewer annual inspections for those retired 20 hour a year Bonanzas would mean GA as we know it would be dead.

Posted by: Greg Goodknight | May 14, 2010 10:31 PM    Report this comment

There have been rumors on this site that Swift Fuel will be around $10/gallon<<

That isn't a rumor. It's fact. Swift said as much at Sun 'n Fun. Now those initial costs and they are betting that scale economies will bring that number down. If their basic assumptions are right-- a very big if--they will find the economies.

In general, even a cursory examination of biofuel economics shows that they are more expensive than existing oil-based fuels. It's unrealistic to believe that Swift or any other bio project is going to match or beat petroleum-derived fuels. The big bet is that cellulosic processes will be cheaper than the starch now used for ethanol.

Maybe. I'll believe it when I see it. Call me an open-minded skeptic.

Posted by: Paul Bertorelli | May 15, 2010 5:44 AM    Report this comment

You're right Greg, but in your case you pay for the mod in fuel savings in 4 years. I'm afraid with the fuel situation, the Bonanza and 210 will go the way of the 310 and the DC3. There will be some owners who resurrect them, but a lot will go away. I saw a Baron go for 25k + a 15k annual the other day, and it was a nice airplane. The owner had 150k invested in it, died, and his widow was left holding the bag. It's too bad, it really is. The twin guys are facing right now what us single engine guys might face over the demise of 100LL. I guess to those still flying them, the silver lining is that used parts will be easy to get.

Posted by: Josh Johnson | May 15, 2010 7:19 AM    Report this comment

While attending Aviation Safety School, a required reading assignment was Games People Play, and one of the negative, destructive "games" described was "Ain't it Awfull". I think we may be letting ourselves play it here. We still have 100LL and there is no time line for it's demise yet, $10 swift fuel isn't here, nobody has had to spend big bucks in engine mods yet, and technology has more tricks up its sleeve. Change can be problematic, but let's not run scared, just smart and politically active.

Posted by: Burns Moore | May 15, 2010 7:52 AM    Report this comment

Part of being politically active is noting when an entity like TCM makes a decision that, on the face of it, is contrary to the interests of past customers. An old marketing game is "run it up the flag pole and see if anyone salutes it" and I want the resultant salutes to TCM to be clearly noted.

There would be economies of scale for Swift, and it might make sense to blend the 106 octane Swift (iirc) with 94UL stock to come up with the 100UL fuel. Since G100UL is entirely a petroleum product, I expect its price would be comparable to 100LL. More expensive to refine but once TEL is removed avgas should be less expensive to distribute. However, we don't know what is in G100UL and there might be something unhealthy that will generate some controversy.

That all said, if the guys on the inside of TCM can make an economic case for requiring rebuilds of virtually all of the engines they've built for Bonanzas over the past half century, I'd like to hear them make it. Out in the open, not in press releases.

Posted by: Greg Goodknight | May 15, 2010 1:03 PM    Report this comment

Well, in the automotive world we've had ethanol blended fuel shoved at us, when it cannot compete without massive government subsidies. If the auto groups can't stop the ethanol madness, I think we are quite naive if we think we can retain leaded fuel forever. I hope we get a dual-fuel situation like Hjelmco has set up in Sweden, then let the aircraft operators make the choice if they want to pay more for low lead, or convert and save. I assume your local small airport might go 94UL and the biggies go 100LL. There could also be semi-portable fuel farms set up with the unleaded at airports to give people a choice. I know the oil companies want to go one fuel only, but I assume there would be a pretty good profit margin for a startup company to offer unleaded avgas at, say, 50 cents/gallon under the current (or future) price of 100LL. By the way, not all Bonanza engines will need replaced for lower octane fuel - there are mogas STC's for many Bonanzas.

Posted by: Josh Johnson | May 15, 2010 3:09 PM    Report this comment

Also Greg, I think your disdain for TCM is misplaced. It's the EPA and FOE that are pushing the elimination of 100LL - I'd suggest complaining to them. Also, the Cessna Columbia's, most SR22's and the 540 powered Bonanza's I believe are FADEC and capable of running 94UL.

Posted by: Josh Johnson | May 15, 2010 3:27 PM    Report this comment

A lot depends on what TCM means a small differential cost over the price of a 100LL engine costs will be.

Currently there is a large premium to go diesel at TBO and hope you recover the operating cost over time. If they can achieve a 10% premium or less it will be a game changer.

I'm more concerned by the remaining fleets of big radials and warbirds will be irrevocably harmed by the loss of 100LL

Posted by: RAY DAMIJONAITIS | May 15, 2010 9:46 PM    Report this comment

The Bonanza mogas STC's are for the lower compression E-185, E-225 and the lower compression O-470 and IO-470 engines. The high compression IO-470N (260HP), IO-520 (285) and IO-550 (300) have been in Bonanzas delivered since about 1960, and there are no mogas STC's for those. A half-century's worth of production by TCM, and it is unseemly that TCM would choose to throw us under the bus.

There are two 100LL replacement fuels on the table that would not require major modification of all modern Bonanzas, virtually all of which are powered by TCM engines.

I believe the planes RD is concerned about can run the Swift and GAMI fuels.

We used to have a fuel infrastructure that supported multiple grades but that was dismantled when we standardized on 100LL, I doubt that an ad hoc two fuel hodgepodge is going to fly.

Diesels have large cooling problems, and seem more suited to high drag aircraft that can accept the additional drag required of the radiators without big performance losses. Good for Cessnas with wing struts, not so good for 176kt Bonanzas.

Posted by: Greg Goodknight | May 16, 2010 2:13 PM    Report this comment

Mr. Goodknight: I've read your comments and I sympathize with you and all others in your situation; but I'd like to clear up a few things: TCM is not, by choice, not throwing anyone under the bus. The state-of-the-art technology 50 years ago for your aircraft was big-bore high-compression engines. It is not your fault times have changed and the standard fuel of the day is going away, but it, too, is a relic of the past. It's also not your fault that general aviation powerplants as an industry have not experienced ANY substantive changes in those past 50 years we are discussing; you were not given an opportunity to change, because there WAS no change.

The situation stinks.

I need an education here: back when leaded fuels disappeared from automotive use, we owners of big-bore high compression BMW Motorcycle engines (anyone here familiar with the 'Airhead' design?) were forced to rebuild their cylinder heads with new hardened valve seats and new exhaust valves to tolerate unleaded fuel. From an engineering point of view, I understand is this on of the problem on these aero engines. Yes, I do understand the aero engines will see a loss of power with lower octane fuel, and since these old dinosaurs cannot change spark timing without FADEC, detonation is a problem as well. Are there solutions from an engineering perspective that will allow these engines to run on 94UL?

A comment about diesels, Mr. Goodknight....the SMA is air cooled...no radiators.

Posted by: TRACY SMITH | May 16, 2010 4:45 PM    Report this comment

Radiators, whether using circulating coolant or cylinder fins, still need airflow.

There is nothing sacrosanct about 94UL, it's just a common stock. Great for Cessna 150's and Cherokee 140's. Nor is there any issue of state of the art having passed; to get maximum work from an internal combustion engine, fuel octane needs to be higher.

TCM made a decision to support the adoption of a fuel which is suboptimal for the planes that actually use most of the fuel. There are two fuel proposals that would work as is, and might me more if players like TCM had given the support.

The Swift manufacturing process is one of converting biomass to petroleum-like compounds. What I have not heard is whether hydrocarbon feedstocks could be used to make essentially the same fuel. Paul B, I realize Swift has been formed specifically to make a biofuel, but if essentially the same fuel can be made using crude oil or coal or oil sands, and more economically, I'd be all for it.

And then there's G100UL, which should be about the same price as 100LL.

Posted by: Greg Goodknight | May 16, 2010 5:44 PM    Report this comment

Greg, I too would suggest that your characterization of TCM as throwing you under the bus is misplaced. TCM is merely responding to what it sees an existential threat to its business. One can debate the technical merits, but the company is smart enough not to disenfranchise owners of its current engines, which number more than 100,000. As for the diesel, it's simply a no brainer--they need it to develop international and emerging domestic markets. I don't think they have a choice, so it gets down to build your own or buy someone else's and develop it. They chose the latter and we'll see if it was the right decision.

Have a look at the DA42 variants. They are diesel powered and not especially high drag. The SMA engine is an air hog and it does have two rather largish heat exchangers for intercooling and oil cooling. Nonetheless, the engine delivers performance comparable to the O-470 avgas engine.

If TCM pulls off a 300-HP six-cylinder version, it could have a winner.

Posted by: Paul Bertorelli | May 17, 2010 6:30 AM    Report this comment

I would like to know why Cirrus did not adopt the SMA diesel. I am assuming it has something to do with the large intakes not conforming to the sleek airframe of the Cirrus. This may be SMA and TCM's biggest hurdle. The winter kit was not much of an issue for PFC.

Posted by: DAVID VILLANE | May 17, 2010 6:48 AM    Report this comment

The right place to direct your concern is to AOPA, EAA, GAMA, NBAA and the FAA. Consider this: A well-respected company--GAMI--with a proven track record of superior engineering in powerplants has boldly stated it has developed a fuel that's a drop-in replacement for 100LL. Moreover, it claims that this fuel can be refined with current refinery technology and at costs competitive with 100LL. This company is willing to demonstrate this to all comers.

Yet...in five months, none of these organizations have launched a *detailed* technical review to examine the veracity of these claims. Fuel is the very lifeblood of the industry and these groups aren't engaged? (To its credit, GAMA did send a tech rep to a G100UL demo. The FAA has not.)

If I were Craig Fuller or Tom Poberezny or Pete Bunce or Randy Babbitt, for cryin' out loud, I'd want a white paper on my desk in 30 days complete with graphs, economic studies, the chemistry...the lot of it. I'd want to test these claims sooner rather than later. If the claims are false and unsupportable, let's find out now and move on to the next thing. To my list, I'd add the CEOs of the engine companies and all the major OEMs.

If G100UL is a player, let's find that out, too. So I'd want to know why this isn't happening. But, according to my progress checks with GAMI, is is not happening.

So there's your bus.

Posted by: Paul Bertorelli | May 17, 2010 6:48 AM    Report this comment

Very well put Paul I will start doing exactly what you are saying with the contacts I know (limited but a start).

Posted by: DAVID VILLANE | May 17, 2010 6:59 AM    Report this comment

Well said, Paul. My letter-writing campaign has now begun.

Posted by: TRACY SMITH | May 17, 2010 7:02 AM    Report this comment

As a long-time diesel driver, diesels for aircraft are in our future in my opinion!

Advantages: 1) burn jet fuel (or almost anything else in a pinch); 2) diesel fuel is a lubricant whereas gasoline is a solvent; 3) greater energy density in diesel fuel; 4) potential >3000 hour overhaul time based on other diesel experience; 5) diesels like to run slow (gasoline engines like to run fast), just what's needed to drive a propeller (no need for a reduction gear in high performance engines); and 6) diesels produce high torque (what a propeller needs ) at medium speeds (measured in N-m or lb-ft), not peak horsepower, which should be the measure of diesel performance, so less engine displacement is needed.

Posted by: Lawrence Gettleman | May 17, 2010 9:07 AM    Report this comment

Absolutely true on all counts, Mr. Gettleman. One question, though.... ...do you think the new generation of compression ignition engines will be able to get traction and market acceptance in the Lycosaurus world of General Aviation? Look how difficult it was to get A&P mechanics to just admit the existance of the Rotax 912!!! I have never seen an industry so resistant to change! Until there is market momentum to TEACH the concepts of compression ignition in our aviation technology programs the diesel is doomed. What good is a new technology engine if no one can or wants to fix it ????? Can your local A&P plug in a laptop and get the operating parameters or change the timing on a Volkswagen TDI? I know I can.......

Posted by: TRACY SMITH | May 17, 2010 10:18 AM    Report this comment

AOPA's review on G100UL can be found here:http://www.aopa.org/members/files/pilot/2010/may/feature_fuel.html

Posted by: Josh Johnson | May 17, 2010 11:19 AM    Report this comment

Tracy is VERY observant. However when avgas gets to euro price [4 times the US price ] then things will change but probably not before there have been casualties.

Posted by: Geoff Waldron | May 17, 2010 12:18 PM    Report this comment

Yes, Tracy, the change will be brought about by the bottom line, I am afraid. Diesels are the dominant fuel in Europe because of their efficiency, less need for high performance vehicles, and the low-sulfur petroleum source in the middle east. We will outgrow the WWII engine and airframe technology slowly. Just look at the improvements in avionics.

I forgot to mention the advantageous absence of an ignition system in a diesel engine which makes it much more reliable (no coil or magneto, distributor, wiring harness, spark plugs, &c.) and will not interfere with avionics. Just supply fuel and air and it will run continuously, once started. The most modern European diesels use a common-rail high-pressure design with either computer-controlled solenoids or piezoelectric injectors. They also emit much less carbon monoxide. Too bad that TCM chose an older design. But that, too, will change.

Posted by: Lawrence Gettleman | May 17, 2010 12:19 PM    Report this comment

I haven't seen any mention of the Exxon refusal to fuel diesels with Jet A. Weren't there concerns about cetane rating and lubricity of Jet fuel? Isn't this a serious problem for diesel aircraft engines?

Posted by: Charles Haubrich | May 17, 2010 12:22 PM    Report this comment

theres a difference between diesel and kerosene

Posted by: Geoff Waldron | May 17, 2010 12:24 PM    Report this comment

I love diesels, but my Bonanza will never have one. It just would not be practical to do such a radical reengining of such a classic (ie old) aircraft, even though my V35A is newer than most of the type 35 fleet.

While I've not flown in it, one of the two Theilert DA42s registered in California is based at my home airport and maintained by an FBO that I regularly use, so I've seen it up close in various stages of maintenance and repair a number of times, a gorgeous plane. I was actually thinking of the Diamond TwinStar when I mentioned drag. I was flying a Cherokee PA-28-161 when the Thielert/Centurion engine burst on the scene, and it seemed perfect for my needs as a retrofit, but for the eventual price and the financial meltdown of Thielert. Low fuel consumption with high service ceiling, needed for IFR in the West. However, as was reported in the press accounts at the time, the slick Diamond, because of the need for airflow, it was a balancing act; lower airflow for good cruise performance, or higher airflow for climb performance, and the FADEC would kick in to limit climb if heat became a problem, which it did. The PA-28, a great plane, is draggy enough as is that the required airflow had little effect on performance.

I look forward to the day that fast, high performing aircraft are powered by diesels, but that is not today. When there's something like an SR22 being powered by a diesel, we'll know a good compromise has been reached.

In the meantime...

Posted by: Greg Goodknight | May 17, 2010 12:50 PM    Report this comment

In the meantime... SwiftFuel and G100UL are turds in Continental's punchbowl. There are many tens of thousands of aircraft that *need* a drop in replacement for 100LL, and I'll be happy to not have lead to deal with when that fuel becomes a reality.

Posted by: Greg Goodknight | May 17, 2010 12:51 PM    Report this comment

I am happy to see progress being made in the direction of diesels for aircraft and am very encouraged to see that TCM has finally gotten involved. I have flown their IO520, TSIO520 and IO550 engines for the last 20 plus years and have been mostly happy with them. In my opinion if they can develop a 300 to 350 horsepower diesel to put in the C206, 210, Bonanza's, Barons etc. they will have it made. Unfortunately it also might be a little late with the growth of the single Turbines like the Kodiak, Caravan and others.

Posted by: Daniel Carlson | May 17, 2010 1:11 PM    Report this comment

I have a hard time unstanding why anyone would build an air-cooled engine for anything larger than a lawn-mower or maybe a weed-wacker. Certainly not to save weight or to increase reliability. After having several older air-cooled motor cycles, I never wanted another air-cooled vehicle. My current 400 cc dual sport bike is liquid cooled and they did not make it liquid cooled to add weight.

Also, for a given power, a diesel requires less cooling than a gasoline engine as it is more efficient and produces less waste heat. A well designed radiator system should produce thrust not drag at higher speeds. You compress the air, add heat and then expand it. This is how a jet engine works. The radiator system on a P-51 Mustang did exactly this.

I also have a hard time understanding why a new diesel would not have electronic injection. It make it quieter, more efficient and, I would contend, more reliable.

I believe that Continental had a 2-stroke, liquid- cooled uni-flow (intake ports but exhaust valves) opposed 4 cylinder diesel on display 10 years ago at Oshkosh. What happened to that engine?

Posted by: Samuel H Drake | May 17, 2010 4:31 PM    Report this comment

I understand that Garmin now has their 400/500 series navigators in about half of the active GA fleet. Why? It's expensive but you sure get a lot for your money - who'd want to go VOR to VOR. I think the lesson to be learned is that there is a retrofit market provided there are huge benefits. FADEC doesn't offer us much now, but if someone came out with a retrofit package that would let, say, a 210 operate on 87 octane E10, I think he'd have a ramp full of airplanes waiting for the mod at 30 grand or so. I understand the fascination of a drop-in replacement, but I'm concerned what the cost will be. If we really want cheap fuel I think the fleet needs to go the way light sport has - we're gonna use the same gas you put in your car.

Posted by: Josh Johnson | May 17, 2010 5:21 PM    Report this comment

Mr. Drake, it is a shame you've not been around to direct aircraft engine development over the past century, but as it stands currently, air cooled mechanical injection gasoline engines have better characteristics. Only real engine developments will change that.

I recall a TwinStar that had both diesel engines fail, dead as a doornail, when the gear was retracted. The single battery was not fully charged and the voltage drop caused by the electric gear retraction caused the electronic engine controllers to simultaneously fail. More redundancy was a fix, but it does go to show that simplicity has its place in aircraft.

Finally, the P-51 cooling system did generate drag, just less than it would have without some of the heat converted to thrust. It's unclear to me that the design would be cost effective in a modern small civilian aircraft.

Posted by: Greg Goodknight | May 17, 2010 5:26 PM    Report this comment

Diesel engines are superior to gasoline engines in propeller-driven aircraft because: 1. Diesel engines run on jet fuel (or almost anything else) and are 30% more efficient; 2. The energy content of diesel fuel is higher than gasoline, which offsets the increased cost of diesel fuel today (2010). Alcohol and similar oxygen-containing additives reduce the energy content of gasoline even more; 3. Diesel or jet fuel is a lubricant but gasoline is a solvent (affects lubrication, esp. at startup); 4. Diesel engines run efficiently at slow speeds. So do propellers. Gas engines run efficiently at high speeds; gas engines use reduction gears; 5. The appropriate measure of propeller performance is torque (N.m/lb.ft) rather than horsepower (W/J.s). Small diesels with high torque performs the same as large gas engines, affecting size, weight, & starter motor req’mts; 6. No need for ignition system (magnetos, high-V wiring, & dual spark plugs) to reduce maintenance. Once started, diesels run continuously as long as they have fuel, air, and exhaust; 7. Diesels all use fuel injection (less sensitive to altitude change); 8. Electronic diesel are managed with 1 control; 9. Oil change/overhaul times much longer because they are built to closer tolerances; 10. Gasoline is more dangerous in a crash. Diesel and jet fuel have flash points of >66°C & >38°C, resp, (combustible liquids). Gasoline’s flash point is <–40°C (flammable liquid). Lawrence Gettleman gettleman@louisville.edu

Posted by: Lawrence Gettleman | December 20, 2010 12:49 PM    Report this comment

If all american Pilots have to pay the same fuel price as we have to pay in Europe (8 dollar /gal), they will change their mind quickly, including the engine manufacturers

Posted by: ludo huybrechts | March 23, 2011 4:27 AM    Report this comment

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