Continental CD-300 in an SR-22T?

Continental recently announced the CD-300 diesel engine. Turbocharged, Jet-A burning, 310 horsepower, 562 lbs (just 25 lbs more than the TSIO-550-K). It was also recently retrofitted by Continental into an SR-22 and test flown in Germany, and Continental was pleased with the results. My question for you Cirrus experts is whether this would work for Cirrus to adopt as their new engine for the SR-22T someday. Obviously this will take a while: Plans call to have the engine ready for review by airframes in 2015 and certification following a year later. Continental will first seek European Aviation Safety Agency certification, followed by U.S. FAA and Chinese CAAC validation.

But is there any technical reason why this engine wouldn’t work for the SR-22T?

http://aviationweek.com/awin-only/continental-expanding-diesel-line-new-300-hp-engine

http://www.flyingmag.com/aircraft/continental-introduces-310-hp-diesel-v6

http://www.aopa.org/News-and-Video/All-News/2014/July/30/Continental-310-hp-diesel-makes-first-flight

Way too early to say, IMHO. You can bet Cirrus is looking. The engine is very heavy (IIRC at least 100 lbs more than the 550) but needs less fuel (lower consumption, higher energy density). Also, that engine needs to be certified (three years?) and it needs to somewhat prove itself.

The Continental website lists the 550-K at 537 lbs

http://www.continentalmotors.aero/uploadedFiles/Content/xHome/Billboards/500series_032012.pdf

The new CD-300 is listed at 562 lbs:

http://www.aopa.org/News-and-Video/All-News/2014/July/30/Continental-310-hp-diesel-makes-first-flight

Either if it is 100 lbs heavier, that is within the range of acceptability given that you need to carry less fuel anyway given the fuel efficiency.

Yes, we are looking at at least 4-5 years for any diesel solution for the SR-22T, it will take a while for this engine to get approval and prove itself before Cirrus would adopt it. But it seems like it would work, doesn’t it?

There really isn’t any weight improvement based on fuel consumption. While a diesel may burn fewer gph, kerosene is about 12% heavier than gasoline per gallon. So the diesel would have to be something like 15% more efficient just to break even on the weight.

Ross makes a good point on the weight issue. Cost could prove to be a big advantage though, as Jet-A is generally a lot cheaper than Avgas. It’s nice that we buy Jet-A by the gallon and get more pounds of energy for a lower price per gallon. There are also some compelling simplicities, i.e. no magnetos, FADEC that are attractive, but I worry about the heat issues in an SR22.

Not sure what the heat issue would be. The problem with these engines historically is the reduction gearbox.

Hopefully Continental has solved the gear box issues that affected their older diesels. Interestingly, the SMA engine on the new 182 JT-A has no prop rpm reduction gear box.

I know Cirrus has explored diesels for years but has never made them work up to standards. Recently, it seems like Cirrus has much of their energy focused on the Vision SF-50. I would bet that the recent developments in diesel technology and the introduction of the 182 JT-A turn some of Cirrus’ attention toward this technology.

Well, they’ve been trying. But the “older diesels” are still affected very much. Now you’ll have 300 instead of 155 horses working on those gearboxes.

The SMA is an old-fashioned engine design from an automotive diesel perspective, completely different from the Thielert/Continental. That’s why it can turn slower.

FWIW, there is no 182 JT-A. But according to Cessna, it will be certified “real soon now” ™.

Cessna is going to have a 182 JT-A at the Rocky Mountain Aircraft Expo, and will be taking folks in test flights. Granted it always takes a long time to get FAA approval, but Cessna is a company with deep pockets and resources to get this done. I think that all Cirrus owners and all general aviation pilots should root for the success of this airplane. Advances in diesel technology could benefit all of us. The quiet, low emitting, fuel sipping, torque producing diesel engines in the automotive world are a far cry from the noisy stinky diesel trucks of a generation ago. In GA we need to adapt to survive, and the green movement is itching to make all fuel more expensive and to impose restrictions on GA. If you bet that avgas will be around in 10 years, and you bet that a no-lead replacement will cost the same as avgas does now, I think it would be a losing bet. The avgas replacement that is chosen will surely be more expensive than it already is now.

Personally, the safety features and comfort features of the Cirrus still make it a much more advanced airplane. I hope that it isn’t too far off that we see Cirrus announce a diesel SR-22. A reliable, Jet-A burning, fuel efficient, quiet operating, low emitting plane with all the safety features of the Cirrus (CAPS, etc.) would be the ultimate personal aircraft. So in sum I really hope the CD-300 can perform as advertised by Continental.

In the interest of apportioning concern, let me clarify that the various diesel engines that Cirrus has tested have all failed to live up to the specifications required for certification. When a diesel engine will not restart in the air at high altitude, that kinda makes it more about the engine than the airframe, eh?

Cheers
Rick

A couple of years ago, I had an occasion to press this issue with the Cirrus engineering leadership. Why no Jet-A powerplant in a Cirrus?

Answer: because every one they tried doesn’t perform as advertised. And certainly, not as required. And they admit that they have tried every power plant available . . . and they keep trying.

You have stated an obvious market requirement. Cirrus agrees with you. They see the opportunity. They don’t see the solution.

Cheers
Rick

This is the problem in a nutshell. Sharp power pulses trash the gearbox. Large flywheels are very heavy. Somebody needs to come up with a new way to get the power to the prop smoothly with a lightweight engine.

Maybe everyone missed this booth at OSH…
iCopaImage.jpg

Gregory,

I and Thomas were at the Press Conference at Air Venture when Continental announced this model. The major development and testing is being done in Germany. At the press conference, they showed a video of the engine being tested (And wait for it) in a Cirrus SR22. On the press stick they gave us is a video showing it flying.

So yes, it works on a CIrrus.

Yes, EPS is also working on an engine and using a Cirrus as the test aircraft. Talked to DIck Rutan for some time on how it flies. Can’t repeat most of what he said.

http://www.flyingmag.com/news/dick-rutan-pilots-first-test-flight-eps-diesel

http://www.aopa.org/News-and-Video/All-News/2014/May/15/Rutan-flies-new-diesel

in fact, I did. Couldn’t find them.

All I’m saying is that it is way too early to get excited about any of these engines. An unleaded Avgas seems just as far away as a higher-power diesel.

John,

Just because it flew doesn’t mean it works. I could make a cirrus fly with any engine. That doesnt make it safe, reliable, or practical.

Ross

There will have to be an alternative to AVGAS, I don’t think there will be a future for AVGAS in a few years, or at least be it for a reasonable price.

Jet A fuel is available throughout the world, Cirrus will struggle to sell aircraft in the rest of the world other than US as the AVGAS is either non existent or expensive. Avgas in UK cost over $12.00 per US gallon.

Continental isn’t the only company working on Aviation Diesel. EPS has also been testing an SR22 with a 350 HP diesel engine called Graflight V-8.

Of course there is also DeltaHawk and an SR20 with a Turbo Diesel.

There will most defiantly be a future for AvGas. There are a few companies including GAMI and Shell Oil nearing completion of an unleaded 100 octane fuel. Shell reportedly spent 300 million in development and claims it won’t cost more than 100LL. At least in the states, gasoline aircraft engines will be around for a long, long time. All this money being spent on diesel powerplants should be spent on a new direct injection gas engine that can run on auto fuel. Diesels will always be heavier due to the fact that their very nature involves detonation.