nevermind. don't wanna get into a fuel debate. shortround said it best.
Last edited:
Question about V-1610-3
- Thread starter tomo pauk
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
GregP
Major
I'll concede that the early German engines were slow turning units, but they got faster with each new variant. The Jumo 213 turned faster than either the Merlin or the Allison. Numbers below:
DB 600 - 2400 rpm, 1036 hp, 1268 lbs dry, 2071 cubic inches, .50 hp/ cu in
DB 601 - 2500 rpm, 1160 hp, 1320 lbs dry, 2071 cubic inches, .56 hp / cu in
DB 603 - 2700 rpm, 1720 hp, 2030 lbs dry, 2717 cubic inches, .63 hp / cu in
DB 605 - 2800 rpm, 1775 hp, 1667 lbs dry, 2176 cubic inches, .82 hp / cu in
Jumo 213 - 3250 rpm, 1726 hp, 2135 lbs dry, 2135 cubic inches, .81 hp / cu in
Merlin 61 - 3000 rpm, 1565 hp, 1640 lbs dry, 1647 cubic inches, .95 hp / cu in
Allison F30R - 3000 rpm, 1475 hp, 1395 lbs dry, 1710 cubic inches, .86 hp , cu in
The DB 601 was a good engine for the time, light and powerful. The DB 603 was considerably heavier and went into the same airframes, making the DB 603 variant of any such aircraft quite a bit heavier. It was worse if the aircraft was a twin. The DB 605 cut the weight penalty in half. The Jumo 213 was the heaviest engine, but made good power.
The Merlin weighed about what a DB 605 did and made about 200 less HP. The Merlin 61 had a 2-stage supercharger.
The Allison F30R was 250 pounds lighter than the Merlin and made 90 less HP, but had a single-stage supercharger. The 2-stage Allisons were about the same weight as the Merlin 61, with the E11 and G6 series being a bit lighter and the F32 being a bit heavier. All made better WER HP than the Merlin, but less Military HP.
All in all, the DB 605 was very comparable to the Merlin 61 and the Allison 2-stage engines, with similar weight and HP. Shortround and Ratsel are correct in that the early German engines were slower-turning, but it seems the German engines "caught up" or at least gained rpm as the war progressed. A natural consequence, I suppose, of seeking more power.
About the fuels, I am receptive to factual reports, but not much given to accepting uncredited articles from unknown sources, as I assume you both would be, too. Obviously we think of the German fuels differently from one another, but maybe we aren't really all that far apart. In my mind there is a huge difference between a 95 octane fuel and a 130 octane fuel. But the opportunity for extra power in the higher octane must be exploited if it is to make any difference.
That means the engines that exploit the extra octane would not be able to run on lower octane fuel without "detuning," but the converse is not true. That is, a German powerplant designed to run on 95 octane (maybe we could call it 95 / 120 ?) would have no trouble running on 130 octane … if the chemical makeup was close. It would not make more power, but would run fine. Unfortunately, the American fuels were NOT chemically similar to the European fuels, and so there were some issue when trying to run an engine designed for one fuel on the other fuel.
I believe the issues could have been corrected, but the USA was not going into production with captured German engines, we just wanted to run them for awhile and see what the German planes would do. Ergo, not much effort was expended trying to make them run at the top of their form. The Packard-built Merlins were tuned for American fuels and, later in the war, the Allisons were tuned for European fuels if destined for Europe … and the issues with the P-38 engines went away. By that time, the P-38 was "out" and the P-51 was "in." In the Pacific, where we ran American fuel exclusively, the P-38 had no fuel issues ... not tat this trhead had anything to do with P-38's ... I just brought it up due to the early issues with European fuels in the P-38 Allisons.
DB 600 - 2400 rpm, 1036 hp, 1268 lbs dry, 2071 cubic inches, .50 hp/ cu in
DB 601 - 2500 rpm, 1160 hp, 1320 lbs dry, 2071 cubic inches, .56 hp / cu in
DB 603 - 2700 rpm, 1720 hp, 2030 lbs dry, 2717 cubic inches, .63 hp / cu in
DB 605 - 2800 rpm, 1775 hp, 1667 lbs dry, 2176 cubic inches, .82 hp / cu in
Jumo 213 - 3250 rpm, 1726 hp, 2135 lbs dry, 2135 cubic inches, .81 hp / cu in
Merlin 61 - 3000 rpm, 1565 hp, 1640 lbs dry, 1647 cubic inches, .95 hp / cu in
Allison F30R - 3000 rpm, 1475 hp, 1395 lbs dry, 1710 cubic inches, .86 hp , cu in
The DB 601 was a good engine for the time, light and powerful. The DB 603 was considerably heavier and went into the same airframes, making the DB 603 variant of any such aircraft quite a bit heavier. It was worse if the aircraft was a twin. The DB 605 cut the weight penalty in half. The Jumo 213 was the heaviest engine, but made good power.
The Merlin weighed about what a DB 605 did and made about 200 less HP. The Merlin 61 had a 2-stage supercharger.
The Allison F30R was 250 pounds lighter than the Merlin and made 90 less HP, but had a single-stage supercharger. The 2-stage Allisons were about the same weight as the Merlin 61, with the E11 and G6 series being a bit lighter and the F32 being a bit heavier. All made better WER HP than the Merlin, but less Military HP.
All in all, the DB 605 was very comparable to the Merlin 61 and the Allison 2-stage engines, with similar weight and HP. Shortround and Ratsel are correct in that the early German engines were slower-turning, but it seems the German engines "caught up" or at least gained rpm as the war progressed. A natural consequence, I suppose, of seeking more power.
About the fuels, I am receptive to factual reports, but not much given to accepting uncredited articles from unknown sources, as I assume you both would be, too. Obviously we think of the German fuels differently from one another, but maybe we aren't really all that far apart. In my mind there is a huge difference between a 95 octane fuel and a 130 octane fuel. But the opportunity for extra power in the higher octane must be exploited if it is to make any difference.
That means the engines that exploit the extra octane would not be able to run on lower octane fuel without "detuning," but the converse is not true. That is, a German powerplant designed to run on 95 octane (maybe we could call it 95 / 120 ?) would have no trouble running on 130 octane … if the chemical makeup was close. It would not make more power, but would run fine. Unfortunately, the American fuels were NOT chemically similar to the European fuels, and so there were some issue when trying to run an engine designed for one fuel on the other fuel.
I believe the issues could have been corrected, but the USA was not going into production with captured German engines, we just wanted to run them for awhile and see what the German planes would do. Ergo, not much effort was expended trying to make them run at the top of their form. The Packard-built Merlins were tuned for American fuels and, later in the war, the Allisons were tuned for European fuels if destined for Europe … and the issues with the P-38 engines went away. By that time, the P-38 was "out" and the P-51 was "in." In the Pacific, where we ran American fuel exclusively, the P-38 had no fuel issues ... not tat this trhead had anything to do with P-38's ... I just brought it up due to the early issues with European fuels in the P-38 Allisons.
I'll just add, C3 is equivilent to 97/130, also Germans always quoted lean setting octane ratings. never high rich. C3 didn't have the best motor knock number at lean, but Rich it excelled, due to the Hydrogenation process and Aromatic content. Compensated by the Boost control, so it wasn't much of a problem. The DB 605 could run either the B4 or C3 fuels, both with or without MW-50. GM-1 can run on either fuel. B4 w/ MW-50 got you 1850ps, C4 w/ MW-50 got 2000ps.
I think it would be worthwhile for some to take a look at this pdf file,
http://www.fischer-tropsch.org/Tom Reels/Linked/A5464/A5464-0638-0654 Item 6A.pdf
Especially look at File 2197 where the rich mixture of C3 is 125.
Info on DB engines,
http://mitglied.multimania.de/luftwaffe1/aircraft/lw/DB605_varianten.pdf
http://www.fischer-tropsch.org/Tom Reels/Linked/A5464/A5464-0638-0654 Item 6A.pdf
Especially look at File 2197 where the rich mixture of C3 is 125.
Info on DB engines,
http://mitglied.multimania.de/luftwaffe1/aircraft/lw/DB605_varianten.pdf
GregP
Major
Thanks for the reports. It goes a long way toward answering the questions about Octane and aromatics.
If I take averages, the Octane rating for B-4 is 90.7 with no rich number and for C-3 is 95.7 / 123.75. Call it 96 / 124, and it averrages 40.5% aromatics.
That is probably why the German aero engines didn;t go to higher BMEP numbers sooner ... fuel.
I already know the DB600 was 2400 rpm; DB601 was 2500 rpm; DB603 was 2700 rpm; DB650 was 2800 rpm, and the Jumo 213 was 3250 rpm. Their BMEP numbers are lower than for Allied engines until the DB605, which is at about 230 or so, and back down to 197 for the Jumo due to higher rpm.
The Allison was around230 and the Merlin was 251 for BMEP. Recall these aer supercharged engines, so the numbers are not unreasonable.
If I take averages, the Octane rating for B-4 is 90.7 with no rich number and for C-3 is 95.7 / 123.75. Call it 96 / 124, and it averrages 40.5% aromatics.
That is probably why the German aero engines didn;t go to higher BMEP numbers sooner ... fuel.
I already know the DB600 was 2400 rpm; DB601 was 2500 rpm; DB603 was 2700 rpm; DB650 was 2800 rpm, and the Jumo 213 was 3250 rpm. Their BMEP numbers are lower than for Allied engines until the DB605, which is at about 230 or so, and back down to 197 for the Jumo due to higher rpm.
The Allison was around230 and the Merlin was 251 for BMEP. Recall these aer supercharged engines, so the numbers are not unreasonable.
the docs posted early give
at page 9 analysis on 10 samples of C3 fuel wuth in average 95.4 octane number with rich number Greater of 125 for 9 samples , and for one 118.5 (that with higher octane number) we can't calcculate a average of rich number, the greater in 8 samples it is not a quantitative.
at page 11 there is an other sample with 95.5 octane number but w/o rich number.
at page 13 there are two samples both with 95.5 octane number and in avarage rated a rich 118% of allied 130 grade
o i think we can tell that late C3 was almost 95/130 maybe also a 95/145
at page 9 analysis on 10 samples of C3 fuel wuth in average 95.4 octane number with rich number Greater of 125 for 9 samples , and for one 118.5 (that with higher octane number) we can't calcculate a average of rich number, the greater in 8 samples it is not a quantitative.
at page 11 there is an other sample with 95.5 octane number but w/o rich number.
at page 13 there are two samples both with 95.5 octane number and in avarage rated a rich 118% of allied 130 grade
o i think we can tell that late C3 was almost 95/130 maybe also a 95/145
GregP
Major
I'd say you are a bit molre opmimistic than I am. Most gasloine has a rich number about 30 points higher than the lean number, not 45 or more points. So, if the bottom number is 95 / 96, then the top number isn;t going to be more than about 125 / 128.
Just my opinion, but it holds for gasolines all over the world pretty well. In any case, that is for the C-3 fuel.
The B-4 is probably in the neighborhood of 90/120, with a not very repeatable batch process.
Just my opinion, but it holds for gasolines all over the world pretty well. In any case, that is for the C-3 fuel.
The B-4 is probably in the neighborhood of 90/120, with a not very repeatable batch process.
You mentioned that the German engines had higher displacements and that with octanes similar to American av gas they might've gotten the power their displacements indicate.
I'd ask, where do the compression ratios fit in?
If it wasn't the gas, those engines were running much higher compression ratios which would've capped both boost and RPM using the same
US grades, no?
I'd ask, where do the compression ratios fit in?
If it wasn't the gas, those engines were running much higher compression ratios which would've capped both boost and RPM using the same
US grades, no?
somewhat I would guess, the advantage would be torque (ft-lbs) and boy did those DB engines make torque!
Your forgetting that C3 is synthetic. I read that the 145(150?) was using up too 50.4% aromatics. Repeatble all depends on the guy doing the tests, and the quality of the sample.
wuzak
Captain
Higher octane fuels would allow the use of more boost with the same CRs.
What Rolls-Royce did, in particular, was to lower teh CR and up the boost.
Similarly, there were two schools of thought for turbocharged race cars in the '80s. One idea was to have low boost high CRs which gave better fuel economy, or low CRs with high boost which gave more power.
There was nothing stopping Daimler-Benz dropping their CRs for moore boost. But I'm guessing that they preferred the way it was done, for whatever reason.
The DBs were in the same neighborhood as the Allison and Merlin if not less actually, probably depends more on the time period/rating obviously.
The DB605 was significantly higher, but I wouldn't put punctuation behind the figure.
The R-2600 and R-2800 trump those figures to put it in perspective.
I'm not sure how that matters, would DB engines be prone to damage if run above 3000RPM?
Their peak power is probably somewhere in that range if not right below it.
Most engines peak power is right above peak torque by a few hundred RPMs.
Of course, that also assumes quoted figures are at peak torque and not at peak power.
Do you know, when it comes to engine ratings in WW2?
Another thought, might mean that DB engines were rated at peak torque and Merlins/Allisons rated at peak power, but i wouldn't know for sure.
GregP
Major
Ratsel,
I wasn't forgetting C-3 was synthetic. I was averaging the reported numbers. The samples averaged 40.5% aromatics and the numbers I got were averages of the samples. If they really did mix it at 50% aromatics, then it should not have been called C-3 anymore, but should have a different designation or the people in the field would not know why their engiens were running differently than the previous batch of fuel did.
I like to give credit where it is due, but don't like to accept better numbers than the real ones. I haven't yet seen one single sample of C-3 with a rich numbers of 145 or above. I am not saying they didn't make it ... I just haven't seen it. The samples I have seen are about 94 / 125 to 96 / 133 or so. If I see a report on a sample with higher numbers, it still has to be averaged in with the other samples.
C'mon, real is real. You can't take 10 samples and quote the highest one as the grade of the fuel, for German, British, American, or Japanese fuel. You have to take averages of many samples and assume the fuel they got was that or perhaps slightly better or worse.
Also, I didn't say American fuels were better or worse. I said they were a different chemical makeup and had a different percent aromatics than European fuels. When you know what is coming down the carb it is easier to jet correctly. Changing the fuel would likely require specialized tuning and jetting, but it could be done by a knowledgeable engine technician.
Last, if a German engine, say a DB605, was designed to run on 95 / 130 fuel, it would likely run fine on 130 / 150, but would not make more power unless the boost or compression ratio were changed to accommodate the new Octane.
I wasn't forgetting C-3 was synthetic. I was averaging the reported numbers. The samples averaged 40.5% aromatics and the numbers I got were averages of the samples. If they really did mix it at 50% aromatics, then it should not have been called C-3 anymore, but should have a different designation or the people in the field would not know why their engiens were running differently than the previous batch of fuel did.
I like to give credit where it is due, but don't like to accept better numbers than the real ones. I haven't yet seen one single sample of C-3 with a rich numbers of 145 or above. I am not saying they didn't make it ... I just haven't seen it. The samples I have seen are about 94 / 125 to 96 / 133 or so. If I see a report on a sample with higher numbers, it still has to be averaged in with the other samples.
C'mon, real is real. You can't take 10 samples and quote the highest one as the grade of the fuel, for German, British, American, or Japanese fuel. You have to take averages of many samples and assume the fuel they got was that or perhaps slightly better or worse.
Also, I didn't say American fuels were better or worse. I said they were a different chemical makeup and had a different percent aromatics than European fuels. When you know what is coming down the carb it is easier to jet correctly. Changing the fuel would likely require specialized tuning and jetting, but it could be done by a knowledgeable engine technician.
Last, if a German engine, say a DB605, was designed to run on 95 / 130 fuel, it would likely run fine on 130 / 150, but would not make more power unless the boost or compression ratio were changed to accommodate the new Octane.
Last edited:
Another mousetrap to be avoided in the avgas debate. According to the British reports published at Fischer-Tropsch Archive, German C3 was close to 95/130 by Allied standards. Thus German engine should have been able to match Allied performance as far as fuel is concerned. These same reports mention that in 1944 a new C3 was introduced with performance almost equal to the British 100/150 fuel. Another nail into the coffin for those whining (not pointing to anyone specific) about German poor quality fuels. And should end the debate on 145/150 C3.
Kindest Regards
Kindest Regards
Thanks Ratsel, like I said Crumpp challenges convention with what he says sometimes but they're false conventions and he hasn't been wrong yet. He also got into the deleted outer guns debate on Fw-190A fighter deliveries, backing his word with not just engineering docs but the minutes of Focke Wulf meetings from something like mid-41 to the end of the war, like everything discussed in boardrooms and research labs. I tend to take him at his word, gives me a warm glow when he gets backed up by corroberation which happens every time, after some kicking and screaming among the audience.
post76 aero engines power figures are actually confusing because they're torque producers but to put a context on it you show angular momentum or prop hp. To infer this you show crankshaft bhp. To get thrust you combine prop design and performance qualities. Everything about aero engines is actually torque, which in the ideal math model is 3000rpm, you multiply torque produced at this engine speed with +/- rpm # to get bhp for the engine speed in fictionally perfect test conditions. You want your eco cruiser based on minimum hp to keep the plane aloft and min gph fuel consumption. You want your max cruise or reg cruise at peak torque and max safe output at peak hp or max safe engine speed whichever comes first.
Whilst larger displacement engines run into piston speed and flame front issues limiting engine speed they firstly gulp larger volumes of atmosphere on intake strokes naturally, and secondly to put out similar hp to a Merlin at fewer rpm inherently means that you are producing a tremendously higher torque output at all normal engine settings, have much more powerful cruise settings with similar fuel consumption (higher altitude and more efficient cruise conditions), and workup from cruise to combat trim is virtually instantaneous in a Daimler, in any Merlin it takes a moment or two before your prop horsepower climbs back above about 750bhp. You have better engine response and more immediate power on tap during normal flying, shorter take off runs on rougher strips (muted by underweight Messer frame which pancaked when the DB605 was introduced if you opened full throttle too quickly on take off runs), there were a number of differences which a smart pilot or mission planners can make beneficial.
Might be worth pointing out that whilst the combat range of the BoB Spit and Messer are about the same, the Spit has better endurance, the Daimler went a little further burning fuel a little more quickly so they even out, again the same but different. As the DB-605A was developed into the AS and D variations the piston crowns and other features evolved so that successive fitments of the family in high performance interceptors and fighter-only craft (like the Erla G10), were further developed with an emphasis on cruise performance. These thirsty motors with 1250-1550hp normal military and 1800-2000hp overboost managed to retain the same range as earlier marqués carrying the same fuel load, despite the progressive increase in combat performance settings. A lot of flying time is built around the maximum continuous and 30min climb settings and it is here where the Daimler really shines, performance doesn't drop off very much at these settings where with smaller capacity engines with 3000rpm military ratings tend to suffer at 2600rpm climb settings.
So whilst often being unremarkable in the upper envelope, the thing about the Messer or any Daimler engined plane is that it really shines in mid range performance, and has some genuine advantages.
post76 aero engines power figures are actually confusing because they're torque producers but to put a context on it you show angular momentum or prop hp. To infer this you show crankshaft bhp. To get thrust you combine prop design and performance qualities. Everything about aero engines is actually torque, which in the ideal math model is 3000rpm, you multiply torque produced at this engine speed with +/- rpm # to get bhp for the engine speed in fictionally perfect test conditions. You want your eco cruiser based on minimum hp to keep the plane aloft and min gph fuel consumption. You want your max cruise or reg cruise at peak torque and max safe output at peak hp or max safe engine speed whichever comes first.
Whilst larger displacement engines run into piston speed and flame front issues limiting engine speed they firstly gulp larger volumes of atmosphere on intake strokes naturally, and secondly to put out similar hp to a Merlin at fewer rpm inherently means that you are producing a tremendously higher torque output at all normal engine settings, have much more powerful cruise settings with similar fuel consumption (higher altitude and more efficient cruise conditions), and workup from cruise to combat trim is virtually instantaneous in a Daimler, in any Merlin it takes a moment or two before your prop horsepower climbs back above about 750bhp. You have better engine response and more immediate power on tap during normal flying, shorter take off runs on rougher strips (muted by underweight Messer frame which pancaked when the DB605 was introduced if you opened full throttle too quickly on take off runs), there were a number of differences which a smart pilot or mission planners can make beneficial.
Might be worth pointing out that whilst the combat range of the BoB Spit and Messer are about the same, the Spit has better endurance, the Daimler went a little further burning fuel a little more quickly so they even out, again the same but different. As the DB-605A was developed into the AS and D variations the piston crowns and other features evolved so that successive fitments of the family in high performance interceptors and fighter-only craft (like the Erla G10), were further developed with an emphasis on cruise performance. These thirsty motors with 1250-1550hp normal military and 1800-2000hp overboost managed to retain the same range as earlier marqués carrying the same fuel load, despite the progressive increase in combat performance settings. A lot of flying time is built around the maximum continuous and 30min climb settings and it is here where the Daimler really shines, performance doesn't drop off very much at these settings where with smaller capacity engines with 3000rpm military ratings tend to suffer at 2600rpm climb settings.
So whilst often being unremarkable in the upper envelope, the thing about the Messer or any Daimler engined plane is that it really shines in mid range performance, and has some genuine advantages.
Last edited:
GregP
Major
The link I used was Government Reports, US Navy Technical Mission in Europe, Technical Reoprt Number 145. The data is in the Composition and SPecifications section.
It says C-3 was about equivalent to US grade 130, was rated at 95 Octane, but the lean condition was a bit worse.
So it basically says the C-3 was 95 / 130 and the "95" was really a bit lower, which is what I already said. Thanks for the corroboration. The report does not mention a grade higher than 130, and I have the data I need for further consideration. Thanks for that link.
It says C-3 was about equivalent to US grade 130, was rated at 95 Octane, but the lean condition was a bit worse.
So it basically says the C-3 was 95 / 130 and the "95" was really a bit lower, which is what I already said. Thanks for the corroboration. The report does not mention a grade higher than 130, and I have the data I need for further consideration. Thanks for that link.
The torque of the engine is directly proportional to its output. All engines produce torque.
(RPM * Torque)/ 5250 = horsepower
peak power vs peak torque:
It depends how the engine is rated, and some might actually be rated at peak torque and the lower RPMs would indicate so.
To illustrate this i will use rough figures from the Allison, if rated at 1475hp, at 3000rpm it produces about 2600 lbs/ft torque.
If run at 3300rpm, theoretically, it produces less torque, say 2500 lb/ft torque (just guessing here) it would give a total horsepower of 1571.
Less torque more horsepower, but the engine has to work harder.
That's the third component, work. More work, means more consumption, more wear...etc. However, understanding this power element, the engine can get more performance when needed.
Last edited:
Shortround6
Major General
I believe the engines were rated at horsepower not torque. Torque may be a consideration when comparing two widely different engines WITHOUT reduction gears. Such as why can any number of biplanes of the 1920s carry 3 people with a 90hp Curtiss OX-5 engine and there are darn few post WW II planes carrying more than 2 people powered by a Continental C-90. The 503cu in V-8 gave it's 'power' at 1400rpm while the 201 cu in four gave it's power at 2475rpm. Without reduction gears those are the propeller speeds and the OX-5 swung a much bigger propeller which gave more thrust at low speed. The OX-5 also weighed 390lbs without water and radiator compared to the 186lbs of air-cooled C-90.
The WW II V-12s had reduction gears and constant speed ( constantly adjusting pitch) propellers. This tends to equalize things. It is a bit like a drag race with two cars. one with a 5 liter engines and 4:33 rear end gears and the other with a 7 liter engine and 3:00 rear end gears. The rear end gears will multiply the torque of the smaller engine at the rear wheels to match the bigger engine.
Both R-R and DB (and a number other companies) offered the same engine with different reduction gears to suit fighters and bombers/transport aircraft. Later on the further development of Constant speed propellers ( more blades, greater pitch range) may have cut down on the need for different gear ratios.
The air frame designer was interested in horsepower, they assumed that if the power was there they could get the propulsive effect/efficiency they wanted with either the right reduction gear or the right propeller or a combination of both. If the basic HP wasn't there no amount of fiddling was going to help.
The WW II V-12s had reduction gears and constant speed ( constantly adjusting pitch) propellers. This tends to equalize things. It is a bit like a drag race with two cars. one with a 5 liter engines and 4:33 rear end gears and the other with a 7 liter engine and 3:00 rear end gears. The rear end gears will multiply the torque of the smaller engine at the rear wheels to match the bigger engine.
Both R-R and DB (and a number other companies) offered the same engine with different reduction gears to suit fighters and bombers/transport aircraft. Later on the further development of Constant speed propellers ( more blades, greater pitch range) may have cut down on the need for different gear ratios.
The air frame designer was interested in horsepower, they assumed that if the power was there they could get the propulsive effect/efficiency they wanted with either the right reduction gear or the right propeller or a combination of both. If the basic HP wasn't there no amount of fiddling was going to help.
