ive been thinking what if the germans would have bulit the 109 with an uprated diesel engine im thinking around a 1000 to 1200 hp i ask because diesels get better range while making the same amount of power which would mean being able to carry the same loadout as a gas plane but over a extended range
a diesel 109 ?
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GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The Luftwaffe did have diesel engines in service, but they were used in transports and long-range recon types.
It may seem like a good idea, but diesel engines back in the 30's and 40's were heavier than their gasoline counterparts and were not well suited for rapid throttle demands as was needed for a fighter in combat.
It may seem like a good idea, but diesel engines back in the 30's and 40's were heavier than their gasoline counterparts and were not well suited for rapid throttle demands as was needed for a fighter in combat.
Shortround6
Major General
Ooooookaaaay..................................
What do you project as the weight of this hypothetical engine, using the technology of 1940 or there-abouts?
Diesels worked in long range planes because the extra weight of the engine/s was offset by the smaller fuel load for the same distance.
If you are dealing with a plane that only held around 100-140 gallons of gas to begin with you don't have much to trade against a heavier engine.
What do you project as the weight of this hypothetical engine, using the technology of 1940 or there-abouts?
Diesels worked in long range planes because the extra weight of the engine/s was offset by the smaller fuel load for the same distance.
If you are dealing with a plane that only held around 100-140 gallons of gas to begin with you don't have much to trade against a heavier engine.
- Thread starter
- #4
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Not a waste of time - how else to learn but by asking questions?
Modern diesel engines have the benefit of alloys and technology that simply wasn't available before and during the war.
Here's a link to one of the more popular diesel engines used in Luftwaffe aircraft.
It has fairly good details to give you an overview of how it was used:
Junkers Jumo 205 - Wikipedia
- Thread starter
- #6
i will read that later thanks
also modern diesel engines life span is 30% of this old ones -at best - this is also "benefit" of "modern engineering approach" - other one is closing gap in fuel consumption between diesel and spark ignition engines - i'm not sure if we are going right direction here
don4331
Senior Airman
A diesel 109 might not be possible but a diesel Fw.190D certainly was:
DB 6xx engines:
DB600 - sire of the 600 series line.
DB601 - V-12 of 33.0l used early in war
DB602 - Diesel V-16 used in airships, e boats in early 30s.
DB603 - V-12 of 44.5l, not ordered by RM so shunned initially
DB604 - X-24 answer to the RR Vulture just not as successful which says a lot about it.
DB605 - bored (aka larger diameter cylinders 601
DB606 - the infamous double V of the He.177 using 2 DB 601s
DB607 - Diesel V-12 of DB603 dimensions, 1,750hp takeoff
DB608 - Further increase of 601 to 36.6 l by increasing stroke.
DB609 - V-16 using DB603 bore/stroke
DB610 - double V using 2 DB 605s
DB612 - rotary valve engine
DB613 - double V using 2 DB 603s
... numbers continue to at least DB632.
Stop the train: Diesel V-12 of DB603 dimensions, 1,750hp takeoff - matches Fw.190D-12 pretty close...
Honourable mention - Ha.201 2 DB601s in tandem
DB 6xx engines:
DB600 - sire of the 600 series line.
DB601 - V-12 of 33.0l used early in war
DB602 - Diesel V-16 used in airships, e boats in early 30s.
DB603 - V-12 of 44.5l, not ordered by RM so shunned initially
DB604 - X-24 answer to the RR Vulture just not as successful which says a lot about it.
DB605 - bored (aka larger diameter cylinders 601
DB606 - the infamous double V of the He.177 using 2 DB 601s
DB607 - Diesel V-12 of DB603 dimensions, 1,750hp takeoff
DB608 - Further increase of 601 to 36.6 l by increasing stroke.
DB609 - V-16 using DB603 bore/stroke
DB610 - double V using 2 DB 605s
DB612 - rotary valve engine
DB613 - double V using 2 DB 603s
... numbers continue to at least DB632.
Stop the train: Diesel V-12 of DB603 dimensions, 1,750hp takeoff - matches Fw.190D-12 pretty close...
Honourable mention - Ha.201 2 DB601s in tandem
Dash119
Senior Airman
Like most things in life, the engineering of diesel engines is a series of trade offs. The "modern engineering approach" in the case of diesel engines was to reduce size and weight. I know this engine is older than you probably envisioned, but it best illustrates the issue. This was a state of the art British stationary engine in 1934. For thirty years it ran nightly providing electric power to a nearly dozen households on a small island in British Columbia. For the next 55 years it was run sporadically without any major maintenance. In addition to the lack of maintenance, the fuel consumption was minimal, far better than any "modern" high or medium-speed engine.also modern diesel engines life span is 30% of this old ones -at best - this is also "benefit" of "modern engineering approach" - other one is closing gap in fuel consumption between diesel and spark ignition engines - i'm not sure if we are going right direction here
The secret to these factors is a long, slow stroke that takes advantage of the slow flame propagation of diesel fuel and robust construction. However, the long slow stroke requires low RPM and a large cylinder, which requires a large flywheel, which requires a more robust crankshaft, which requires a more robust crankcase, etc... This is practical for a stationary application, but not so much for a vehicle of any kind, let alone an airplane. The only way to reduce the size and weight is to increase the RPM. Increases in RPM bring more power, but sacrifice efficiency and durability. The engine in the video produces 30HP @ 300RPM, and the flywheel weighs more that 1500 lbs.
don4331
Senior Airman
That Ruston Hornsby really isn't that efficient - 0.48 lbs fuel/hp/hr. Even the biggest Ruston Hornsby only managed 0.414 lb/hp/hr The Jumo 205 only burned 0.33 lbs/hp/hr.
The most modern high speed diesels don't get as good fuel economy due to the emissions restrictions on them, but they are still in the 0.4-0.45 lbs/hp/hr. You can cut down the flame propagation time, but using very high pressure to make very fine droplets.
Those in ocean liners are getting better numbers, but they turn even slower than that ancient engine.
Cool, reliable engine though.
The most modern high speed diesels don't get as good fuel economy due to the emissions restrictions on them, but they are still in the 0.4-0.45 lbs/hp/hr. You can cut down the flame propagation time, but using very high pressure to make very fine droplets.
Those in ocean liners are getting better numbers, but they turn even slower than that ancient engine.
Cool, reliable engine though.
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
That was a cool video. Liked listening to it. Might not be as pleasant if listening up close though.
Dash119
Senior Airman
It's better up close and personal, not really all that loud. It's hard to hear in the video, but you can actually hear the air "whoosh" into the manifold on each intake stroke. Mechanical music.
Thumpalumpacus
Major
I'd always thought throttle response would be an issue.
Shortround6
Major General
For a snap shot the DB diesel technology levels in the 1930s see
oldmachinepress.com
Diesels require much heavier construction than gasoline engines due to the higher peak pressures in the cylinders.
You could very well make a diesel equivalent in size to the DB 603 but you are either going to be very heavy or not make much power.
Daimler-Benz DB 602 (LOF-6) V-16 Diesel Airship Engine
The DB 602 V-16 was a world-class diesel airship engine built by Daimler-Benz in the 1930s. Because of the ill-fated Hindenburg and the end of the airship era, the engine never left a direct mark o…
oldmachinepress.com
Diesels require much heavier construction than gasoline engines due to the higher peak pressures in the cylinders.
You could very well make a diesel equivalent in size to the DB 603 but you are either going to be very heavy or not make much power.
Dash119
Senior Airman
I'm not an engineer, so what would be the best way to achieve the greatest efficiency if you were do design a diesel engine today? If that was your only consideration, I believe a large slow-speed engine with a long stroke is still your best pathway. Turbocharging should provide a benefit in almost any application, as it did with the Jumo 205. And as an ancillary benefit, you will probably get much greater longevity than you would with a medium or high-speed solution. Slow-speed engines just aren't practical in anything but the largest non-stationary applications.
don4331
Senior Airman
If you're asking what the most efficient use of a litre of diesel would be: gas turbine - you're not starting/stopping anything; lighter too.
For an engine - the opposed piston/2 stroke of Jumo 205 is hard to beat; however, you don't run it as a 2 stroke but rather only inject diesel every other compression cycle on the other cycles, you inject distilled water (and a trace of oil/anti corrosion fluid) and you cool the engine by boiling water. And your exhaust/steam is run into a turbine connected to output.
Really long stroke engines lose efficiency due to weight, anything over 2x bore, you're losing energy heating the cylinder walls and de/accelerating lots of weight.
The double sided pistons like the diesels found in diesels of Graf Spee which made power on every cycle are efficient in so much as no cycle is wasted, but materials to take the heat without cooling don't exist - then you are losing efficiency to water jacket.
Turbocharger wastes energy compressing the air - best you could hope for is adiabatic compression, actual will be significantly worse. You might need a slight touch of intake pressurization to ensure air flow in and out the correct ports. On other hand if you want to make more power for given displacement - turbochargers are your best friend (poor man's gas turbine).
For an engine - the opposed piston/2 stroke of Jumo 205 is hard to beat; however, you don't run it as a 2 stroke but rather only inject diesel every other compression cycle on the other cycles, you inject distilled water (and a trace of oil/anti corrosion fluid) and you cool the engine by boiling water. And your exhaust/steam is run into a turbine connected to output.
Really long stroke engines lose efficiency due to weight, anything over 2x bore, you're losing energy heating the cylinder walls and de/accelerating lots of weight.
The double sided pistons like the diesels found in diesels of Graf Spee which made power on every cycle are efficient in so much as no cycle is wasted, but materials to take the heat without cooling don't exist - then you are losing efficiency to water jacket.
Turbocharger wastes energy compressing the air - best you could hope for is adiabatic compression, actual will be significantly worse. You might need a slight touch of intake pressurization to ensure air flow in and out the correct ports. On other hand if you want to make more power for given displacement - turbochargers are your best friend (poor man's gas turbine).
Ascent
Senior Airman
Possibly the future of heavy duty diesel technology. Be interesting to see where this goes.
Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
DB607 was meant for bombers/long distance flight (and not at very high altitudes). The take off power of 1750PS was actually achieved by using Alchohol fuel, so you need
two fuel tanks (I dont have the particulars of how that system worked annoyingly), and the 607 was down to 625PS by 33,000feet altitude (a bog standard 605A at that point was 790PS, a 603A was 950PS and even an old 601E has 700 at 33,000ft). Diesels tend to have high airflow per unit power, as they need to run pretty lean, so this places a higher
demand on the supercharger size, so they dont make brilliant engines for very high altitudes without being turbocharged - which totally counts them out for any
German single seat fighter.
Today because of the more advanced state of turbocharging, it is a possibility again to make a high performance avaition diesel with good altitude performance, with a reasonable
package size and overall weight.
RED Aircraft – Home of the V12
red-aircraft.com
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fastmongrel
1st Sergeant
If you enjoyed the video then the Anson Engine Museum in Cheshire Great Britain will be the best museum ever.
Anson Engine Museum
Anson Engine Museum - Wikipedia
Unfortunately still closed because of covid but hopefully open soon.
