Diesel engines

[fireflybob]

Am interested in reliability and considerations operating diesel engined power aircraft, in particular PA28 - 161 (Warrior) conversions.

Thanks for any help.

[S-Works]

I flew a diesel converted warrior that was based at Elstree quite a few times. Not exactly my favourite aircraft. Dog slow and stunk of Jet fuel all the time.

It also seemed to be off line a lot for rectification work. Was one of the things that put me off converting my Cessna.

[riverrock83]

I understand that most of the serviceability issues have been sorted. The expensive issue is due to gear boxes needing overhauled every every 500 hours.

Big writeup in October's Flying Aviation News and Resources for Pilots | Flying Magazine magazine. The impression I get is that give it a year and the various options (there are a couple out there) will mature enough to be no-brainers but they aren't quite there yet - so you will still be in the "early adopter" camp if you go that route, with the risks that it entails.

When the gear box TBO has increased to something sensible, with AVGAS 100LL probably not going to be around for ever, the increased fuel efficiency and the lower specific gravity (fuel weighs less) they have the potential to be no-brainers in the future. Not quite sure we are there yet, so you will need to do lots of research and take a small risk.

[John R81]

AVTUR is heavier than AVGAS (SpG 0.82 compared to 0.74).

Denser hydrocarbon = more calories / volume

[A and C]

Myths ?

As usual there is a lot of uninformed comment about Diesel engines ( not thankfully on this thread yet!), on the whole the technology had matured to the state that I would put a Theilert engine in a PA28.

On the whole they are now reliable and have the support of a maintenance organization that understands the engine. Changing the gearbox is not a big job and I am sure that the life will be extended just as it was with the clutch.

The only warning I would issue is that you should only undertake this convention if you intend to do a lot of flying, the new engine will not pay for its self on a low utilization aircraft.

I suspect that Bose-X had flown the 135 HP aircraft, a 150 HP engine is now available and I think that the extra HP will solve most of the problems.

That having been said the aircraft that will benefit the most from the diesel is the Robin DR400, as it has a wing that is better suited for flight at higher altitudes and the ability of the diesel to maintain power up to 12,000 ft due to the turbocharger it should make for a good long distance aircraft.

[YODI]

If there is anything you'd like to know specifically let me know, Im an ex cabair engineer and worked on the 6 Diesel PA28's Daily.

I'm now based in Bournemouth and have just finished rebuilding and flying G-OOFT, G-CETD's engine arrived yesterday as did G-CETE they will be in the sky again soon.

I've been working on the diesels for over 6 years now in the PA28's and DA40's mainly, but the odd 172 aswell. I also did the Thielert course in Germany, so feel free to ask any questions

Oh I'm 110hr PPL too, over 100 of those hours on diesels

[smarthawke]

Do I remember that with the original Thielert 135, a converted PA28-161 compared to a Lycoming powered one:

1. Weighed 160lb more?
2. Climbed at a reduced rate to 2000ft?
3. Cruised 5 kts slower?

Add to the above the cost of overhauling the CS prop (note poorer performance despite the CS prop) and the sparse maintenance cover over a standard aircraft.

[doubleu-anker]

Well I'm surprised the application hasn't been refined before now. The Germans were using diesels in a/c during WW2

From a safety aspect alone, give me a diesel any day. If you are unfortunate enough to be in an accident, the fire risk is reduced somewhat. Although a diesel engine runs hotter than a petrol engine, the ignition source is somewhat neutralised should the engine be stopped.

[YODI]

Im not sure on the comparable figures however, real life figures are.

Climb circa 700fpm @ 80 kts and cruise circa 105kts at 70% (ish)

I can't remember what OOFt weighs I will look on Monday when I'm at work.

Also the Warrior 3 is heavier than the Cadet.

[N707ZS]

I see Multiflight at Leeds has bought three of the Elstree Diesel Pa 28s.

[YODI]

Yes mate they have, Aircraft that are sold by my bosses that have been painted prior to sale generally have the same scheme as those 3 and the one I posted above, which is also for sale if you know anyone.

[Sam Rutherford]

Though not a PA28, our C182 SMA is great. We've had some alternator wiring problems (now fixed hopefully, and not really related to the type of fuel burnt).

But the aircraft flies further, faster, with more on board than the avgas original - and for a fraction of the cost (fuel only, £20/hour instead of £80+).

Fly safe, Sam.

[silverknapper]

Engine Failure Deals Setback for Diesel Cessna 182 JT-A | Flying Magazine

[Silvaire1]

If I were looking at diesel I'd be looking at the whole package, not just fuel consumption. Notwithstanding the post above, one thing that doesn't get highlighted that much is the propeller. Diesels vibrate and otherwise durable aluminum propellers apparently can't take it. Diesels also have a narrow power band so you need variable pitch. The end result is a relatively fragile wood prop (MT on the Thielert) or a carbon fiber prop (apparently a Hartzell on the 182) that's better than wood, but still not as resistant to hangar rash as a fixed pitch slab of aluminum. As with everything diesel related, the 'solution' is fussiness, much increased complexity, and increased maintenance.

[Cows getting bigger]

Sure, some of the maintenance costs have increased. But that needs to be considered against the reduction in fuel costs.

I would happily fly behind a diesel SEP.

[YODI]

Just thought I'd show you what a Thielert Centurion, now called Technify as they were bought by Continental looks like, brand new in a box.

[Bob Upanddown]

Well I'm surprised the application hasn't been refined before now. The Germans were using diesels in a/c during WW2

From a safety aspect alone, give me a diesel any day.

Keep pumping the fuel in and the diesel will keep running. No magneto or other ignition problems to worry about. Simple, low revving diesel would be ideal.

But these are not simple diesels. Because they have opted for an automotive unit, they have had to have electronics and gearboxes and that's has been the cause many of the problems.

But we have Avgas engines because the simple diesels have disadvantages over the lycosaurs otherwise your PA-28 would have been built around a 1940's aero-diesel instead of a 1940's avgas burning lycoming.

I am sticking with my avgas burner cos it suits me and what I fly.

[Bob Upanddown]

Thielerts rely heavily on electricity for the Fadec.

That was the point I was trying (obviously badly) to make. The old diesels didn't need a FADEC but were heavy.
Thielert must have started from the position of "how can we make an aero diesel quickly and solve all the problems?" Answer - use a car engine. But that's where all the problems have been, from using the car engine and converting it.
But look where all the others trying to make aero-diesels are........ nowhere.

[worrab]

It's a bit surprising that the Napier 2-stroke diesel (https://www.youtube.com/watch?v=D3bj47TAYiU) hasn't had further development. Used succesfully (if a little unreliably) in the "Deltic" railway engine in the UK, its compactness and improved - compared with a 4-stroke - power/weight ratio should make it quite a good candidate for aero purposes.

[Sir George Cayley]

It's probably too late now, but I've long felt using the word 'diesel' to describe this family of power plants could lead to confusion.

As I understand it, they are compression ignition engines which inject fuel to create combustion. That fuel is AVTUR (e.g. Jet A-1) and not the smelly stuff out of the black nozzle at Tescos petrol station.

Now honouring Rudolf Diesel by naming all compression ignition engines is a nice thought but miss-fueling is on page one of the list of errors down to human factors.

Just a thought - must go I have to Hoover the carpets

FL