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fireflybob
25th Sep 2013, 08:46
Am interested in reliability and considerations operating diesel engined power aircraft, in particular PA28 - 161 (Warrior) conversions.

Thanks for any help.

S-Works
25th Sep 2013, 09:30
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
25th Sep 2013, 09:55
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 (http://www.flyingmag.com/) 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
25th Sep 2013, 10:05
AVTUR is heavier than AVGAS (SpG 0.82 compared to 0.74).

Denser hydrocarbon = more calories / volume

A and C
25th Sep 2013, 14:51
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
28th Sep 2013, 09:18
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

http://img.photobucket.com/albums/v87/rsyodi/Aircraft/530533_10153246195310447_551673337__zps781692e9.jpg

smarthawke
28th Sep 2013, 11:38
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
28th Sep 2013, 11:55
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
28th Sep 2013, 11:57
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
28th Sep 2013, 19:08
I see Multiflight at Leeds has bought three of the Elstree Diesel Pa 28s.

YODI
28th Sep 2013, 20:57
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
30th Sep 2013, 16:48
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
30th Sep 2013, 23:46
Engine Failure Deals Setback for Diesel Cessna 182 JT-A | Flying Magazine (http://www.flyingmag.com/technique/accidents/engine-failure-deals-setback-diesel-cessna-182-jt)

Silvaire1
1st Oct 2013, 02:17
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
1st Oct 2013, 05:56
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
1st Oct 2013, 07:38
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.


http://img.photobucket.com/albums/v87/rsyodi/Aircraft/20130930_083922_zpsfcd90241.jpg

http://img.photobucket.com/albums/v87/rsyodi/Aircraft/20130930_083922_zps1ce5f904.jpg

http://img.photobucket.com/albums/v87/rsyodi/Aircraft/20130930_083908_zps8d0c6c07.jpg

Bob Upanddown
1st Oct 2013, 08:26
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
1st Oct 2013, 10:58
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
1st Oct 2013, 11:19
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
1st Oct 2013, 11:31
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 :ok:

FL

piperboy84
1st Oct 2013, 12:18
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.

Was wondering how the 182 was working out for you, I still wait in hope of a Maule STC to trade my Lyc in for a diesel.

Cows getting bigger
1st Oct 2013, 18:01
Not quite that simple. For example, the DA42 with Thielert engines is certified for Jet A1 and Diesel (EN 590).

BackPacker
1st Oct 2013, 18:20
True. And I think the most important difference between the two is that car diesel is supposed to have lubricating properties, while Jet-A does not. So if you use Jet-A in an unconverted car diesel engine, things like fuel pumps may seize up rather quickly.

Another issue is that car diesel is less able to withstand low (<-15C) temperatures. So the fuel operating temperatures at which you are allowed to start and to take-off are a lot stricter with car diesel.

When we had the DA40 with the 1.7 Thielert, there was a whole POH supplement about using car diesel, temperature ranges and such. But since car diesel is essentially unobtainable airside, I never bothered to read that supplement in full.

YODI
1st Oct 2013, 18:26
The Operation manual states that if Diesel is used, the Aircraft is not allowed to be started if the temp is -5c or lower.

You're also only allowed to using Anti icing agents with JET A not with Diesel.

We sold 5 x PA28's to Bangladesh this year, and when I was there building them back up and running them they were on normal Diesel, you'd never know the difference even in flight, but the lesson of only using clean fuel can be an expensive one in termos of LP and HP pumps.

BackPacker
1st Oct 2013, 20:35
I just checked the DA40 flight supplement which we had for the 1.7 Thielert, and the situation is even more complicated.

With diesel, or a blend of diesel and Jet-A (anything over 10% diesel would be considered a blend) the minimum engine starting temperature of the fuel is indeed -5C, but the minimum take-off temperature is +5C. So once you've got the engine started, you've got to wait for the fuel in the main tank to reach +5C. Furthermore, fuel transfer from aux to main is not guaranteed if the fuel in the aux tank is lower than +5C.

In contrast, the limit on Jet-A is -30C, both for starting and take-off.

The fuel is heated because the excess fuel in the common rail is led back to the main tank, via a coil in the aux tank. And the fuel is heated up in the common rail not just because of the ambient temperature in the engine compartment, but also because of the pressurization to ~400 bar.

A and C
1st Oct 2013, 20:48
Like a lot of people in this industry you are critical of a technology that you only have a passing knowlage of.

Most composite propellers are a wooden core with a carbon of glass re enforced plastic outer shell with a metal leading edge.

Damage to a metal prop is usually limited to blending the damage ( removal of metal) down to a manufactures limit.

Damage to composite blades is a more complicated issue but damage to a blade of a depth that would write off a metal prop is more than likely to be able to be repaired on a composite prop.

The composite Hartzell prop is a very different item being almost totaly carbon reenforced plastic, I am told with a metal spar. This is so new that I have no idea what the manufactures have mandated in the way of repaires but it looks like a very efficient areofoil and I am sure will out perform most other props.

Silvaire1
1st Oct 2013, 23:47
Silvaire 1 - Like a lot of people in this industry you are critical of a technology that you only have a passing knowlage of. [sic]A and C - after the usual but in my case directly relevant university education, my 25 year career has mostly been in rotating machinery development, with lead technical and management responsibility for rotating machinery research projects individually funded up to about $35M, and including composite reinforced rotors. Among other things, I'm currently involved with engineering in that role for Thielert's largest diesel engine customer. There's a lot to learn in this field, but I don't think "passing knowledge" is an accurate description.

A close friend and colleague who I see at least weekly at his factory is the principal, designer, analyst and manufacturer of what are arguably the world's leading high end carbon fiber bladed propellers, sold in substantial volume for quite some years now. The blades FYI are 100% carbon fiber composite, very strong, with either hollow or foam core. Other than being produced with really clever manufacturing technology that he's developed over the last 20 years, the blades also have super-hard electro-formed nickel leading edges produced by a low cost proprietary method, fitting perfectly, and wrapping around the tip for maximum protection. These are a very good design, with good blade shape and excellent performance... but the blades still aren't as tolerant of abuse or abrasion as an aluminum prop. Damaged carbon fiber blades are not often repaired, they are generally replaced. Sometimes the manufacturer can replace the nickel leading edge, if the damage is limited to that part of the blade.

Of direct relevance to the diesel engine discussion, I also own and operate an MT 'composite' propeller that I inherited with my own aircraft, almost identical to those used with Thielert diesel engines, and relatively old fashioned in its construction. Mine was overhauled and reinstalled last month. It has a very thin layer of fiberglass over the wood, intended only as a weather shield, not as blade structure. The structure is entirely wood, retained with lag screws, but applicable to diesels because wood damps out torque pulsations well and thereby limits the resulting blade stress. The very thin layer of fiberglass is used because any thicker layer tends to delaminate - for structural reasons the glass layer needs to be very thin and very light, so thin you can see the grain of the wood through the fiberglass. The stainless leading edge MT uses is also rudimentary old-style technology, formed mechanically and much softer than a nickel leading edge. The net result in my opinion is a quite fragile propeller. If it survives any abuse that might be applied between overhaul cycles it really does require the 6 year overhaul period recommended by MT. A completely different world of fragility, complexity and maintenance when compared to the normal fixed pitch prop on a 172 or Cherokee, and also IMO much less durable than an aluminum CS propeller.

Perhaps that may be useful to those who would like to build a genuinely greater than passing knowledge of composite propellers, particularly as currently applied to diesel aircraft engines.

Take care.

Sam Rutherford
2nd Oct 2013, 07:12
And referring back to an earlier post, the SMA engine has no gearbox and if power fails can be managed manually without the FADEC without issue.

A and C
2nd Oct 2013, 07:26
That is all very interesting but your first post on the subject did sound just like the usual head in the sand critsisum of new Technoligy.

I find that following years in the maintenance business that we have substantially less MT prop blades written off at overhaul than we do metal blades, this can only be because blades are more damage tolerant in terms of overhaul limits.

The in service damage to metal and composite props seems to be much the same, mostly on the leading edge as you would expect but the leading edge non structural metal shield on the MT is more damage tolerant in the fact that damage to to won't start a fatigue crack as it can on a metal prop

I can only speak as I find on the aircraft we look after but the MT props are fitted to a diverse types ranging from Thielert powered PA28's & Daimonds to Extra 300 types so I do get to see props from a wide slice of this industry and would take a guess that the cost of ownership of an MT prop is likely to be on average 10-15% lower in terms of overhaul costs.

Katamarino
2nd Oct 2013, 17:24
Having flown a little over 70 hours in an SMA powered 182 so far, and experienced no fewer than three alternator failures of varying types, I can attest to the value of the mechanical back-up mode; given how often the electrical system fails, the aircraft would be frankly dangerous without it.

The mechanical back-up mode limits the power you can use, typically slowing one down by about 10 knots in cruise, and it also tends to cut the engine completely if power is reduced below about 1000 RPM (idle is 600ish). This will really screw you up on landing if you're not ready for it. Ultimately, it's far preferable to engine failure when your battery drains though.

The SMA is also very prone to over-heating in high ambient temperatures.

I'd love to fly behind the newer version of the SMA engine and see how things have been improved.

I've also flown behind the Thielert in both DA40 and Robin applications and had no issues there. Overall, I'm a big fan of diesels.

horizon flyer
2nd Oct 2013, 23:41
I have been following aero diesels for ages and I believe there are more in development than their are avgas engine companies at the moment.

Technically an externally scavenged two stoke is a better choice for a diesel,
more power pulses per rev and lower peek torque pulses. With 4 cyl 4 strokes, aka the SMA & Centurion the prop is driving the engine 30% of the time. So the prop is experiencing high torque reversals, not good, brute force engineering over common sense.

These are all 2 strokes

The nicest is the Zoche 8cyl twin row radial at 300hp for the weight of the unreliable IO360. Runs like a sowing machine. But I think it has turned into an EU grants scam.

The US Delta Hawk V4 200hp is looking very good not certified yet.

The Wilksch inverted 3/4 cyl is also very good.

There are many opposed piston units in development, nice low vibration designs. With some like the Ecomotors OPOC and the FairDiesel novel designs.

Diesels are coming but I hope the 2 strokes will win in the end, so much better.

TwoDeadDogs
4th Oct 2013, 03:05
@backpacker, surely the best way to preheat the fuel is to use a fuel heater/oil cooler like a CFM 56. Two jobs for the price of one. @yodi, can you provide a link to the bangladeshi operation?

regards
TDD

YODI
4th Oct 2013, 09:10
Hi,

Here it is.

TAC Aviation Ltd. (http://www.tac-aviation.com/)

PS. They aren't oprating as a school yet

Subir12bd
20th Jun 2014, 05:01
We have taken 5 aircraft.

ChickenHouse
20th Jun 2014, 11:30
Right now, I don't see the benefit of Diesel widespread. Yes, there are conversions, BUT these Centurion/Thielert/Technify have no longer TBO, they have TBR! So, no more overhaul, time's up is equal to get a new machine. Then you have the gear trouble with 300h between replacement and this itty nitty clutch, you have to have not to wreck the engine on stop. Further on, they don't run without electricity - I had so many Fadec failures, I cant count any longer.

I am keen on trying the SMA in the Cessna JT-A, as my feeling tend to see the gearless real-aviation Diesel still as an option. The automobile conversions in my eyes are not. Development cycles to press the last cent out of the buyers pocket in automotive is so short, it is not compatibel with the long cycles in aviation.

One remark to the EN590 issue - yes, there are engines out, that state compliance with EN590, BUT - BIG BUTT, this refers to the "old" EN590 only with pretty much defined max 5% RME addition - in secret they altered the EN590 to include up to 7% FAME instead of RME, which is unspecific fatty acids bio crap. This standard Diesel from tap is not compliant to aviation use.

YODI
20th Jun 2014, 14:05
SUBIR, I know this, I built all 5 for you :)

Yodi

ChrisVJ
21st Jun 2014, 18:23
As a diesel ignoramus I'd be very interested if someone could explain what it is that makes the engines that power current Le Mans winners so powerful and still light enough for racing.

I also wonder why the manufacturers of auto conversions all go for heavy steel four and six cylinder engines and not, say, the VW ten cylinder aluminium engine. If I read the advertising right it puts out 300 hp. at about 3,500 revs. If it was derated to 200 hp it would be right in its best torque range and might not even need a gearbox.

Granted it is complicated, (four stroke, twin turbo etc,) but then twelve cylinder 27 litre twin supercharger engines were reliable enough just after WW11, surely we could use a ten cylinder engine today and with those small pots and small crank offset the vibration might be less too.

Solar
22nd Jun 2014, 01:06
Reading the latest Pilot mag it would give the impression that with the newer breed of diesels there is indeed a place for them on light aircraft.
My main concern is not so much the technical side of things as all or most of these will undoubtedly be rectified at some stage. My worry is what our taxes loving government will do to the price of "aircraft" diesel fuel and Jet fuel when diesel powered aircraft are in the ascent (pun intended).
As has happened to the automotive side of things and yes I do understand that modern diesel fuels are more refined but not to the extent where they are dearer than petrol.

gasax
22nd Jun 2014, 10:17
The diesels at LeMans are there because of the fuel formula, demanding much higher efficiency than the petrol classes.

Unfortunately the longevity of those engines is measured in a race (especially if it lasts 24hrs!).

If you read any of the autobiographies of post war commercial pilots you will find numerous engine failures. That is why we still have the whole multi-engine mindset in aircraft. I used to know a chap who flew Super Constellations, 32 cylinders, turbo and super charged engines. He said it was almost unusual to make an Atlantic crossing and have 4 fully functional engines at the end, they were nearly always nursing one!

Diesels will come but it will need some serious money and good engineering. To date neither of those have really happened.

The Wilksh cannot really be built in serious numbers due to the cost/complexity of its gudgeon pin arrangement.

The Thielert and other conversions offer no real advantage and as noted above have a TBR - which is really a killer in terms of value.

Deltahawk - dunno I've been watching the website for years, will they ever produce an engine?

SMA? massively expensive and it seems still having issues.

Patience is required it seems!

cumulusrider
23rd Jun 2014, 15:54
A question.
If props on diesels are subject to vibration and tourque reversal problems why can you no add a cush drive? By this i mean the rubber shock absorber arrangement used on motorbike rear wheels to damp the pulses from single or twin cylinder engines.

Andrewgr2
23rd Jun 2014, 16:20
Good question!
Even 4 cylinder motor bikes have rubber hub dampers in their rear wheels - or at least my 600 cc Yamaha did. More of a problem to incorporate in an aircraft engine where the prop is bolted onto the end of the crankshaft, but should be possible where there is a gearbox in between which, I believe, is the case with most modern engines.

YODI
23rd Jun 2014, 16:24
The Technify (Thielert Centurion) engine has a reduction gearbox with a dual mass fly wheel and clutch.

Jan Olieslagers
23rd Jun 2014, 17:00
Indeed a slipper clutch is the usual answer to vibration in aircraft piston engines. It is especially critical in engines with few cylinders but with a reduction gearbox; the Thielert indeed but the Rotax 912 also. Though ISTR only the later 912's have one.

Mine certainly has one, too, and I have had reason to be grateful for that when I milled the prop to pieces yet the engine came to no harm.

Some smaller engines, especially car conversions, use belt drive, which serves as reduction gear and as a damper all in one.

I never heard of using some block of rubber as a vibration damper, curious as to why - it seems a viable idea.

ChrisVJ
23rd Jun 2014, 20:36
IIRC some of the earlier versions of Rotax engine had slipper clutches. There was some problems with them and for a while they didn't. Then they put them in again so I suppose they cured whatever the problem was. (Mine doesn't.)

Lotus cars and, I think the Triumph Herald line used to have rubber 'doughnut' flexible drive. One of its problems was that it could 'wind up' and then release causing uneven drive.

I'd expect that in a propeller at some frequency the rubber drive could be expected to create an oscillation where instead of smoothing out small vibration it actually caused a much bigger one.

As I understand it one of the ways of minimising vibration is to have more cylinders of smaller size, making the oscillating parts smaller in relation to the mass of the block and head. That is another reason I am surprised no one has tried the Tuareg 10 cyl. Al. engine.

The Junkers design had a problem with vibration as the piston timing was offset so the valves were opened and closed more efficiently. I don't know if that was still so in the Deltic design but it did have more cylinders and lots of pistons! Probably the sheer size and weight of the block and the locomotive it was mounted in had a lot to do with making the deltic engine acceptable in railways.

gasax
24th Jun 2014, 08:26
The basic problem with virtually all of the diesel designs is weight.

Looking at the VW V10 engine, its weight is variously given at between 600 and 800lbs. And this is a new weight saving design using through bolts down into the crankcase to strengthen it. To that has to be added a gearbox.

The equivalent 300hp Lycoming an IO-540 has a dry weight of 480lbs. So a massive difference.

The V6 VW TDI has a weight of 420lbs, plus gearbox, but it 'only' makes 220 hp.

The same comparison has been made between the O-320 and the Thielert, although with the lower power engines the differential, whilst still there, is smaller proportionately. The Thielert conversions made much of lower fuel consumption - which does mask the additional weight.

ChrisVJ
25th Jun 2014, 20:56
I'm disappointed to hear the Toureg engine weighs so much. Further reading that wasn't available last time I looked (years ago) says that it has a balance counter shaft and the crank is loaded with extra counterweights too. One would have thought that an all aluminium and rather compact engine would weigh less.
There is, of course the weight of all the extra bits, two turbos etc.

You probably wouldn't need a gearbox. Apparently the engine give its full power and enormous torque all the way down to 2,000 revs.

gasax
26th Jun 2014, 08:01
I think the devil is always in the detail. The Ford Ecoboost engine had a tremendous write up in the press. Carried to Detroit as excess baggage, footprint no large than an A4 page.

All unfortunately completely untrue!

The excess baggage engine actually is marginally smaller than the unit is replaces - its footprint is actually larger than A3! Even better its dry weight is over 200lbs, so it must have been a robust handbag the chap was carrying(?)!

So the Ecoboost is somewhat lighter than the engines it replaces, it is somewhat smaller than the engines it replaces - but the Rotax 912iS is significantly lighter and more compact than the 1.0 Ecoboost.......

Jan Olieslagers
26th Jun 2014, 08:11
@ChrisVJ: these balance weights and balance shaft all have their weight, too, and MUST have their weight to be any good. Here comes in the natural superiority of the boxer engine, which doesn't need all these additions to run smoothly.

As for needing a gearbox: yes, modern diesels develop maximum torque at very low revs - the 3,0 Iveco in my van even at 1400 rpm! - but, though torque is important, we still want power at the prop, and power is torque multiplied by rpm. Revving up the engine will still bring improved performance. Whether a gearbox brings enough improvement to justify the added weight/complexity/maintenance is any designer's decision.

ChrisVJ
26th Jun 2014, 18:36
Jan

I was suggesting that the V10 could be used at, say, 2,300 revs as it gives easily 200hp at that speed. It would also get over the usual problem with Auto engines, that they are not designed to give their rated power for more than a few seconds.

At 200hp and 3,200 revs I was looking at the V10 for an RV, maybe an RV8. However if it weighs 600lbs plus it won't work. And why would one build a V10 needing all that balancing when you could build a V8 and not have it? Were the 2 extra cylinders that important?

What I don't understand about engines could be written in a book the size of the bible.

vee-tail-1
1st Jul 2014, 15:38
http://www.weslake.eu/news/newspages/dieselareoengine.html

Patience chaps :)
the modern version of Junkers opposed piston, supercharged two stroke high power to weight diesel is on the way.

There have been numerous false starts like DieselAire, Gemini, Zoche, etc.

One thing for sure, to simply take a Lycosaurus avgas design and turn it into a diesel is not going to work well. Any more than trying to put a Mercedes car engine into an aircraft. The amount of technical fixes needed to make these false starts work defeats the object. The object being simplicity, reliability, economy, and safety.

Perhaps wisely Weslake are avoiding the certified route for development and using LAA type aircraft for initial flight tests.

The Weslake diesel has successfully run at 80HP on the dynamometer. It will be on display at Sywell for the LAA rally, where the company plan to run the engine fitted to a Gruppo Trail aircraft.

This engine is similar to an already operating marine version. The aviation version will have the belt driven water pump and injection pump relocated at the rear, and driven from the two cranks. This will give a more streamlined frontal area.

The Weslake diesel could become a direct replacement for Rotax , Limbach, and VW type, 80HP engines. No more carb heat, ignition systems, valve gear adjustments, AVGAS/MOGAS problems, fire danger, etc. Lets hope the development goes smoothly and quickly.

vee-tail-1
4th Jul 2014, 13:45
The Weslake diesel has successfully run at 80HP on the dynamometer. It will be on display at Sywell for the LAA rally, where the company plan to run the engine fitted to a Gruppo Trail aircraft.

This engine is similar to an already operating marine version. The aviation version will have the belt driven water pump and injection pump relocated at the rear, and driven from the two cranks. This will give a more streamlined frontal area.

The Weslake diesel could become a direct replacement for Rotax , Limbach, and VW type, 80HP engines. No more carb heat, ignition systems, valve gear adjustments, AVGAS/MOGAS problems, fire danger, etc. :ouch:
Lets hope the development goes smoothly and quickly. :ok:

gasax
4th Jul 2014, 13:57
The 912 ULS has an installed weight of about 64kg. Any info on what the Westlake currently weighs?

Mechta
5th Jul 2014, 08:56
Here's the spec for the marine version:

BWM Lightweight Diesel Marine Engine

Specificationhttp://www.bwmribs.co.uk/files//M-80%20Diesel%20Engine/BWM%20Diesel%20M-80%20Engine.jpg
Engine Type: Supercharged Opposed Piston
Layout: 4 Piston - Horizontal
Bore & Stroke: 74.2 x 77 mm
Displacement: 1332 cc
Rated Power: 80 BHP (60kw) at 4800 Output RPM
Dry Weight: 70kg
Fuel: Diesel
Cooling System: Closed Loop – Water / Glycol Mix
Oil System: Dry Sump
Electrical Supply: 12 Volt
Dimensions: Width: 612 mm / Height: 425 mm / Length: 450 mm


Its hard to tell if Weslake (who designed the engine) have gone for the simplicity of a mechanical injection system, or the preformance and efficiency of common rail. Maybe they will offer both?

The output RPM of the marine version could be reduced for aircraft applications by changing the ratio of the geartrain between the outboard crankshafts and the central propeller driveshaft. This should be neater than adding another reduction gearbox on the front.

I wish them well with this project. They have been working on the concept for years.

Jan Olieslagers
5th Jul 2014, 09:09
Curious: elsewhere the same marine engine is stated to produce 100 BHP?

BWM Ribs - BWM Diesel Marine Engine (http://www.bwmribs.co.uk/bwm-m-100-diesel-marine-engine/)

Self-correction: the company announces a 80 BHP engine and a 100 HP one - both with the same bore and stroke and producing their power at the same RPM. Addition of a second stage turbo? Different compression ratio?

vee-tail-1
5th Jul 2014, 09:19
The report in LAA mag suggests plenty of scope for weight saving in the aviation engine. At present it is some 5 kilos heavier than the Rotax, but thinner castings, lighter gears, etc, could reduce the weight a lot. Mechanical injection systems can be optimised for max efficiency at the most used rpm. Being independent of an electrical system would score for reliability.

Mechta
5th Jul 2014, 09:22
Jan, it may well be a difference in injection system, or simply the application for each engine in terms of longevity vs. performance. There are so many variables on a turbocharged diesel, such as boost pressure, porting, number of injector pulses and their duration plus emissions considerations that the cylinder capacity is not an overriding factor.

Jan Olieslagers
5th Jul 2014, 09:38
Yes. Come to think of it, IF the engine has FADEC, it can be easily tuned to a wide range of max power limitation.

Regarding FADEC dependency on electrical system, reliability &c: Rotax have a nice solution there, powering their ignition system from magnets rotating on a flywheel over pickup coils. Surely something akin could be done for powering a FADEC? Even doubled (i.e. two sets of coils), to further increase reliability?

ChickenHouse
5th Jul 2014, 09:46
Small Marine Diesel ??? They have a completely different application scheme. They usually run at best economic RPM, which is quite often around 25-30% power setting. They usually never run at 65+%, as in aviation.

Mechta
5th Jul 2014, 10:25
Chickenhouse, Bear in mind the application for the BWM marine diesel engine is in rigid inflatables (RIBs) which tend to be use higher power settings than engines in displacement vessels.

Given Weslake's history and track record, I'm confident that they know what they are doing.

Regarding the difference in output between the BWM 80 and BWM 100 engines, I've just found the answer in the 'company pedigree page. Our new lightweight BWM Diesel M-80 Supercharged or M-100 Diesel Turbo Supercharged Opposed Piston Engines make us the clear market leader in the industry for size, power and reliability.