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rabauss
7th Feb 2011, 08:06
I write a diploma on the topc Otto (avgas) and diesel engines for small aircraft operating base and I need information about this topic. I appeal to men smarter, because you have an opinion or knowledge about this topic. I'd be very grateful if you could post this kind of information to me, because I can not find such information.

Does anyone has any experience flying a plane compression, maybe is/has oprating(ed) a diesel aircraft, so what is its plusses and minuses comparing to similar avgas airplane. (maintenence, flying, installiation compression engine, whats its features etc). If you have not operating/ flying it, maybe you know somebody who has or you know how to get thiskind of information.
All posts are welcommed, thanks in advance

DERG
7th Feb 2011, 08:24
Please tell us what level of diploma you are working on. Is this post-matura? Say level at 18 yrs old to 22 yrs old...Dipl.Ing level? Please tell us.

Regards

rabauss
7th Feb 2011, 10:07
It is not post- matura, (finishing secondary scool / wikipedia) I think. I´m studying in collage, s.o. If you think that the complication for diploma is not enaugh... The information is hard to get, because there isn´t no more information on engine manufacters homepage besides engine data. On www.dieselair.com (http://www.dieselair.com) is a newsletter, like "Cessna 172 has new diesel engine mounted or there is a new engine coming up". And, maybe some on you have flown with diesel engine airplanes. I need more info, and more specifically, certain facts about airplanes, then I can put all things together.
Besides, I´m doing diploma for my first time and I only asked for little help, if the thread is not in topic then you can put it in lock.

Volume
7th Feb 2011, 14:30
Be careful not to confuse the comparison of a WWII technology engine with a 21st century engine, but really an Otto vs. Diesel comparison !
In principal if you need a light engine which is most efficient close to maximum power and does have its maximum torque close to max power (this is what an aircraft and a propeller requires) then Otto is the clear answer.
If you want to have the best absolute efficiency and the highest efficiency at low power levels, including high torque at low speed (this is, what cars and even more trucks require) then Diesel is the answer.
Limiting factor for Otto is the speed of the flame which limits the size of the zylinder. This means you can not efficiently produce more than approximately 50 hp per zylinder (uncharged) at a typical propeller speed. So it is either a geared engine or lots of zylinders or supercharging if you want to go beyond 300 hp. For Diesel it is more the speed, than the zylinder size which limits it, which is no problem as propellers need to run 1500-2500 U/min depending on the exact diameter epending on the total power you need. This is about the speed at which an ungeared Diesel is best.
As aircraft engines are all about flying, meaning high altitude, turbocharging is almost a must if you do not want to have "high and hot" density issues. Diesel are much easier and much more efficient to turbocharge.

hope that helps

Jhieminga
7th Feb 2011, 14:36
Have a read through this thread: http://www.pprune.org/jet-blast/393597-aero-diesel.html

grounded27
7th Feb 2011, 17:11
This is an interesting subject, never knew a diesel piston aircraft engine existed. Not to sound like a smartass but all the diesel engines in the sky were jet engines to my knowledge. From what I understand diesel is nothing more than jet-a with oil added for lubrication, more or less kerosene.

I would believe cooling and weight would be issues.

con-pilot
7th Feb 2011, 18:12
A few years ago a company here in the US marketed a twin Diesel engine powered aircraft. I'll try and find something about it, cannot remember the name of the aircraft or the company.

Also, either the British R101 or R102 airship, can't remember which right now, was powered by Diesel engines, it was the Government designed and built airship that crashed, resulting in loss of many crew members. As far as I know, the Diesel engines had no factor in causing the accident.

An excellent book on this airship design is "Slide Rule" by Nevil Shute (Norway).

DERG
7th Feb 2011, 18:34
zoche aero-diesels homepage (http://www.zoche.de/)

I would send them an email about your work.

I think they will help you.

Regards

Mechta
7th Feb 2011, 18:39
Advantages
No carburettor icing
No magnetos
No spark to cause radio interference
No mixture control
Can be run on Jet A (if injection pump can cope with lower lubricity compared to automotive diesel fuel)
Fuel system less susceptable to vapour lock
Max torque occurs at lower rpms
Does not require stoichiometric fuel/air ratio
Usually offers significant reduction in fuel consumption
Fuel does not boil off at altitudeDisadvantages
High compression ratio requires stronger and heavier components
Torque reversal at low rpms is damaging to reduction drives and alternators (torsional damper required on reduction drive and sprag clutch on alternator)
Technology for aircraft use is still maturing
The USA, the largest potential market, does not offer big cost savings on the fuel, only on efficiency of operation
Fuel is heavier
Leaks on high pressure fuel pipes a fire risk if near hot surfacesFour stroke diesels allow engines to be based on automotive units, such as Thielert, Austro Diesel, Peugeot etc.

The French SMA engine is four stroke but does not appear to be based on a car engine.

Two strokes such as the Wilksch WAM125 and Weslake W100, offer more firing cycles per revolution.

The most proven diesel engines in aircraft were the Junkers Jumo 205 and 207 engines used in the Junkers Ju86 Bomber and the Blohm & Voss BV138 flying boat. These were built under licence as the Napier Culverin, which was developed into the Napier Deltic Engine used in minesweepers and locomotives. Napier also made the Nomad compound diesel engine which was intended for the Avro Shackleton but never used in it. The Nomad was for a long time (may still be?) the most fuel efficient aero engine ever built.

allyn
7th Feb 2011, 19:43
An obscurish diesel aero engine that was test flown in a Stinson Reliant. Sadly, WW II intervened and it was used to power tanks instead. After the war it was forgotten. Some info links below:

http://www.oldengine.org/members/diesel/duxford/Guiberson.htm

http://www.enginehistory.org/Diesels/Ch3.pdf

Mechta
7th Feb 2011, 20:10
Allyn, Thanks for posting the links to the Guiberson diesel. I knew there was a pre-war American diesel radial, but I had never heard of this one. I'm surprised it hasn't found its way into any American experimental aircraft, as there appear to still be fair few around. Google says they were uses in Stuart tanks, landing craft and generator sets.

Machinbird
7th Feb 2011, 20:41
There is a liquid cooled diesel engine manufacturer in my general area that has been plodding away steadily over the years and is getting close to certifying their engines.
DeltaHawk Diesel Engines (http://www.deltahawkengines.com/)
There are some flying in experimental testbed aircraft. USN is also interested last I heard.
Compared to gasoline engines, a very significant improvement in specific fuel consumption.

no-hoper
8th Feb 2011, 03:18
CENTURION ENGINES - Home (http://web.thielert.com/typo3/index.php?id=601&L=1)

Home (http://www.austroengine.at/?changelang=2)

Diamond Aircraft :: Home (http://www.diamond-air.at/home0+M52087573ab0.html)

rabauss
8th Feb 2011, 08:24
Thank you for answers. Does anybody know, how about noise, vibration, maintenence? I spoke by e-mail with president and chief operating officer for Finch Aircraft and he said that noise and vibration are heavier and maintenence is costlyer than avgas piston engine. In my opinion, the maintenence should be cheaper, because in diesel engine is less parts to worry about (except cooling issue and gearbox of course). But then again other companies tell otherwise; for example: SMA (http://www.smaengines.com/spip.php?rubrique25)
What do you think?

Mechta
8th Feb 2011, 13:32
Rabauss,
I suggest you go back to your man at Finch aircraft and ask him to clarify what he means by more expensive. Thielert/Centurion had some components (torsional damper, gearbox, oil nozzle for connecting rod little end) which were upgraded on their 1.7 engine, and due to the company operating in a 'Chapter 11' type bankruptcy state, these upgrades were not covered by warranties as the might otherwise have been. This has been discussed at length over the last couple of years on Pprune, so type in Thielert or Diesel in the search function and have a good read.

Vibration may be more at idle RPM, due to the engine's higher compression ratio resulting in more torque reversal. A lot would depend on the design of the engine mount and any anti-vibration mounts used.

I don't see why diesels should be significantly cheaper than a petrol engine to make, although a few parts are still sourced from the automotive industry which would bring prices down with mass production. As there are comparatively few around, the development costs are still being absorbed in the engines being sold, and the parts count is significantly higher with many high performance precision components (such as gearboxes, injection pumps & injectors).

Homebuilt aircraft using uncertificated car diesel engines are a totally different matter. In many cases the engine is secondhand with a homebuilt reduction drive and operating costs are 'peanuts'. Gaz'aile 2 (http://gazaile2.free.fr/index.php) translation to English here: DIYer Builds Peugeot AX 106 Diesel Engine Powered Wooden Aircraft - Auto Motto (http://www.automotto.org/entry/diyer-builds-peugeot-ax-106-engine-powered-wooden-aircraft/)

DERG
8th Feb 2011, 13:35
"In my opinion, the maintenence should be cheaper, because in diesel engine is less parts to worry about"

Wrong. More parts..you need to really study the differences.

The BIG issue is fuel "freeze" at below say 5C...very common in cloud.
Ask them how they keep the fuel above say 5C in flight.

Another issue is fuel cleanliness. Ask them how they keep the fuel clean.

Ask them how the engine is controlled at altitude...say 3 000 metres.

Volume
8th Feb 2011, 14:01
And not to forget, you should compare the torque over speed curve with the propeller curve and have a look at the torque over crankshaft angle curve. The first one demonstrates that a diesel always needs an adjustable (typically meaning constant speed) propeller, while the second one lets you estimate the TBO of your propeller blade bearings... close to zero! That´s why the Thielert needs a torsional damper. Diesels are doing incredible torque peaks at the time of fuel explosion while an otto burns the fuel smoothly. Of course there is a lot you can optimize with electronically controlled high pressure injection, but that adds plenty of complexity, sources for failure, life limited components, maintenance costs etc.

the dean
8th Feb 2011, 14:20
Hi Rabauss,

I have been flying the Thielert Diesel engine in a 172 now for five years or so...(first the 1.7 and now the 2. litre engine). If you want to set out any questions about handling please do and I will try to help...or else PM me for the information.

Please bear in mind...I only fly them...I do not have a lot of technical data as others have kindly given you here....but as to flying a Diesel/FADEC engine, I will help if I can.

con-pilot
8th Feb 2011, 15:36
no-hoper

Diamond Aircraft.

That was it.

Thank you.

Mechta
8th Feb 2011, 17:16
DERG, Could you please elaborate on what you mean by "fuel freeze"?

My understanding is that with most aero diesel engines running on Jet A1, the fuel would have to get to -47°C to get fuel waxing, and this also seems to be a thing of the past with automotive diesel thanks to modern additives. The bulk of fuel in the tank and the temperature generated by the work done in the injection pump would suggest these stay warm too?

I have heard of intercoolers overcooling under some conditions, but that isn't a fuel issue.

As for fuel cleanliness, why would this be any worse than for any other fuel or engine type? Aircraft, in most cases, operate in a much cleaner environment than earthmoving equipment, off road vehicles, etc. and effective filtration works for them.

mono
8th Feb 2011, 18:49
Indeed DERG.

Diesel as in the cycle. NOT the fuel you get at the petrol station.

DERG
8th Feb 2011, 21:21
I see...thats wunnerful if they can do that.

No issues at all then.

Thanks for the heads up

Regards

the dean
9th Feb 2011, 11:40
Rabauss,

I answered your PM....but as the reply took me so long, the system logged me out...so I'm not sure if you got my replies.:ugh:...I hope so....I'd hate to have to do it all again....:{

post here and tell me if you got the replies.

The Dean.

Halfbaked_Boy
9th Feb 2011, 11:48
This is an interesting subject, never knew a diesel piston aircraft engine existed. Not to sound like a smartass but all the diesel engines in the sky were jet engines to my knowledge. From what I understand diesel is nothing more than jet-a with oil added for lubrication, more or less kerosene.


Hehe, last Summer I spent the majority of the time flying 172s in Ireland. Drove a Mitsubishi truck with a big ass tank in the back. Drove it into filling stations, topped it off with diesel (or red/green diesel if we could get hold of it), drove to the farmstrip, and pumped it straight into the 172.

Not a hiccup in 300 hrs worth of that. :ok:

mono
9th Feb 2011, 17:40
Hmmm, Halfbaked.

What exemption authorisation did you use??? I know there's a MoGas exemption is there one for forecourt diesel too?? (UK CAA) Plus I think A1 is cheaper than forecourt fuel so I'm not sure why you were doing it.

rabauss
15th Feb 2011, 04:11
I did not got your reply in pm, if you bother, write again

jimjim1
15th Feb 2011, 05:02
I like the look of the deltahawk project.

V4 (6/8 to follow) two stroke diesel 150-200hp.

No valves
No engine electrics AT ALL
Integral cylinder and head so no gaskets
Water cooled
Turbo + supercharged
Will continue to run with supercharger OR turbo failure
In event of complete cooling liquid loss (water n glycol I think)
can be run indefinitely at 50% power.
No reduction gearing needed (or indeed supported)
18,000ft critical altitude
Runs on jet fuel
Better fuel efficiency than lycoming
Same weight as lycoming
Better fuel availability than AVGAS

The engine's operational principles are shared with the largest
and most efficient internal combustions ever made. Large/huge
marine diesels.

See their web site for more details.

I have no connection whatsoever with Deltahawk.

UNCTUOUS
19th Feb 2011, 13:19
Those Diamond twins were a bit lethal with any interruption of electrical power whatsoever.

That needs some debate and consideration. nIt's happened more than once.

Fate 1, FADEC 0: a dual engine failure in a Diamond Twin Star highlights the technical gotachas of FADEC-driven engines. It's a cheap lesson for all manufacturers. | Goliath Business News (http://goliath.ecnext.com/coms2/gi_0199-6984004/Fate-1-FADEC-0-a.html)

Big Pistons Forever
20th Feb 2011, 00:26
I am not sure that it is entirely correct to blame the FADEC for this accident. The POH clearly said that a dead battery must be charged before flight. The crew chose to ignore this warning used an APU to get it started ( unapproved procedure) and as a result suffered a double engine failure and crashed the aircraft.

I personally know of one Continental gas powered twin Cessna that suffered a double engine failure and crashed when the aux pumps were selected to "high" instead of "off" at 300 feet AGL after takeoff. The POH clearly warns that against this yet the pilot was ignorant of the limitation. How far do we have to dumb down an aircraft so it won't bite even if you do stupid things ?

vee-tail-1
20th Feb 2011, 18:55
No one has mentioned the Gemini engine.

www.ppdgemini.com/ (http://www.ppdgemini.com/)

Volume
21st Feb 2011, 11:26
Is that Gemini the 3rd or 4th attempt of what was (is) also known as Diesel Air Ltd. (http://www.dair.co.uk/), Laukötter, Golle or whatever company which presented this engine on the Aero 2001 ?
Since Junkers (http://www.bredow-web.de/Triebwerke_und_Flugzeugmotore/Junkers_Jumo_205/junkers_jumo_205.html) sucessfully applied this System in the 1030s and built several thousands of them for long range seaplanes it is a little bit like nessie... From time to time somebody surfaces with yet another version of this engine.

rabauss
15th Mar 2011, 20:02
Here are some engine manufactors, that I could find, if anybody has interest, google it:

Austro engine GmbH
Centurion Aircraft Engines AG
Deltahawk
Wilksch Airmotive
Diesel Air Limited
Powerplant Developers Limited
Teledyne Continental Motors
SMA Safran Group
Zoche
Raptor Turbo Diesel
ECO Motors
Costruzioni Motori Diesel of Atella, Italy
BRD SrL of Italy
Developments GmbH and RED Aircraft GmbH in Adenau, Germany
and, fo course Gemini

Sam Rutherford
27th Jan 2012, 13:06
No response from halfbaked, but I'd be interested to hear from anyone else who has put 'forecourt diesel' in their 'diesel' plane - rather than JET-A or JET-A1.

Wondering about flexibility when 'out there'.

Our present aircraft has a mogas STC for that exact reason (although the potential ethanol content remains a problem).

Fly safe, Sam.

AmericanFlyer
27th Jan 2012, 15:40
The Hindenberg was powered by four Damiler-Benz DB 602 Diesel engines, V16's.

Denti
27th Jan 2012, 17:01
Sam, centurion engines are certified to run on Jet A1 or Diesel (EN590) right out of the box, or any mixture of both fuels. Dunno about others, but think is possible that austro engines aims for the same certification, haven't checked their website though.