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Diesel: why is it not taking off?

Have you any idea how much the S1204 would be likely to cost? Weightwise it might fit some of the SSDR aircraft (e.g. Luciole, Spacek designs).

No idea, but I would imagine this is something that is designed to fit very specific specs for military drones, it is not designed as a cost effective solution for recreational aviation.

It’s funny. Traditional glow engines for RC are in fact two stroke diesel engines running on methanol/nitro. Then you have 4 stroke glow, that is a 4 stroke diesel running on methanol/nitro. In the later years big engines with ignition and running on gasoline has become popular in RC, basically ordinary two stroke gasoline engines found everywhere. Electric is probably the most popular though.

Car = full power for acceleration, 25% power for cruise, little weight sensitivity

Aircraft = full power for acceleration, 65-75% for cruise, high weight sensitivity.

Simple works better for aircraft.

Yes, I agree. A car also makes lots of acceleration and breaking which makes energy recuperation useful. An aircraft can simply use speed and altitude to glide.

Last Edited by LeSving at 01 Jun 11:05
The elephant is the circulation
ENVA ENOP ENMO, Norway
Private field, Mallorca, Spain

Maybe we should also put to rest the “car 25% power for cruise – plane 75% power for cruise” old wives’ tale.

Do the math on yours – mine cruises at 65% power (@2.5 gph…) and the engine weighs LESS than a comparable similar hp aero installation. I’m pretty sure you could bolt a reduction box on it and still end up lighter than an aero engine.

Design and alloys have moved on since the 1960es believe it or not.

Last Edited by Shorrick_Mk2 at 15 Jun 08:23

It’s indeed incorrect but it keeps coming back. Aero engines are just outdated designs, there is no cleverness to them from a 2014 point of view. Yes, they are very service friendly and can be composed of parts from a dozens manufacturers — because they are so primitive and their tolerances are so bad that all kinds of parts can be fitted on and a field mechanic can do the work with a few simplistic tools.

The Centurion engines are very reliable according to the statistics and they are car engines with several parts replaced by more lightweight versions, they are not heavier, more durable versions of the car engine.

I really find it odd for Continental to continue both with the Centurions and the SMA derivative. I bet they will can the SMA design. What they had in Friedrichshafen looked pretty bad from a workmanship’s point of view. It’s based on the old SMA engine and that one wasn’t great at all.

Agreed. Probably we could also do away with the “liquid cooling = extra drag” mantra. This has already been proven wrong in the 1940es.

Unfortunately, with cheap fuel, cooling has been solved by “throwing more fuel through the engine” and people have accepted it as a optimal engineering design in spite of having no real idea (until the advent of GPS) what power settings and speeds they fly at for a given fuel flow.

Aero engines are just outdated designs, there is no cleverness to them from a 2014 point of view. Yes, they are very service friendly and can be composed of parts from a dozens manufacturers — because they are so primitive and their tolerances are so bad that all kinds of parts can be fitted on and a field mechanic can do the work with a few simplistic tools.

Whatever aero engines are or are not (Lycoming/Continental), they are very much fit for purpose. If Centurions, SMA, Austro were such great designs, we would see them everywhere by now. High tech this and that and some theoretical superiority means nothing if all that cleverness do not translate well to real world applications in the field. It really is all about engineering, transforming technology and theories into well working machines. A Lycoming is an engineering masterpiece in all it’s “outdated” simplicity. A Centurion is an engineering disaster of complexity.

The elephant is the circulation
ENVA ENOP ENMO, Norway

How is a design that is heavier AND uses 4x more fuel for the same amount of output power “fit for purpose” – unless the purpose is “use more gas and spend more money”?

An engineering masterpiece… excuse me while I ROFL.

Last Edited by Shorrick_Mk2 at 15 Jun 08:48

You are right LeSving, it all comes down to well working machines in the end. And the point is that, complex or not, by now the diesels (in particular Continentals and Austros) are indeed proving that they are easy-to-use, reliable, efficient and environmentally-friendly machines. While using fuel that is available anywhere.
The adoption is slow, but hey, what do you expect in this depressed GA-world of today!

Private field, Mallorca, Spain

How is a design that is heavier AND uses 4x more fuel for the same amount of output power

Any Lycoming has higher HP/kg than Austro/Centurion. A Lycoming cost 1/4-1/3 of an Austro. A Lycoming lasts for 10,000 hours at least, and an overhaul cost half of a new engine. An Austro last for 2000? hours and a “overhaul” cost 2 X factory new Lycomings. A 360 in an RV cruises at 55% power at 160 knot using 20-25 l/hr. Put an Austro in an RV, and it won’t even take off due to weight and CG changes.

Besides, since when exactly has fuel distribution become an unsolvable problem? Since when has fuel distribution become costly?

The elephant is the circulation
ENVA ENOP ENMO, Norway

Not in a flying school environment. An o320 last 2400 hours. Plus u can bet on a new top end at half life. Plus numerous days lost due mag problems and spark plug fouling.

As soon as the thirleirt gets a 1800 hour TBR from a flying school prospective the lyco will be dead in the water.

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