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Xiolablu3
05-28-2009, 06:53 AM
Just been thinking about MW50 and Ntrous Oxide after reading Manus thread, and wondered why the Allies never used it?

It seems to me that a Griffon SPitfire or Tempest with Mw50 would have been super fast at lower alts.

Or was it not compatible with the Merlin/Sabre?

Did the system add a lot of weight? Was it just seen as an added complication? Did it drastically lower the engines life?

Look forward to reading your answers http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

stalkervision
05-28-2009, 07:15 AM
the american hot rod association still needed it? http://forums.ubi.com/groupee_common/emoticons/icon_confused.gif http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Hay, someday I may Nos my car up and blow out some cylinders..! http://forums.ubi.com/images/smilies/winky.gif

http://www.holley.com/data/Ads/pictures/purgeBrackets_cpn.jpg

Hay not a bad deal huh? http://forums.ubi.com/images/smilies/icon_twisted.gif

JG53Frankyboy
05-28-2009, 07:20 AM
Originally posted by Xiolablu3:
Just been thinking about MW50 and Ntrous Oxide after reading Manus thread, and wondered why the Allies never used it?

It seems to me that a Griffon SPitfire or Tempest with Mw50 would have been super fast at lower alts.

Or was it not compatible with the Merlin/Sabre?

Did the system add a lot of weight? Was it just seen as an added complication? Did it drastically lower the engines life?

Look forward to reading your answers http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

P&W used it a lot in its radials

stalkervision
05-28-2009, 07:32 AM
info says it was used first on the PW 4360 and on this plane I didn't know existed till now. The F2G Corsair http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif

http://upload.wikimedia.org/wikipedia/commons/thumb/7/78/F2G-1_Bu88458.jpg/800px-F2G-1_Bu88458.jpg


The Super Corsair! Not in il-2 though.. http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif



design work started in 1939!

AllorNothing117
05-28-2009, 07:43 AM
Might tht coursair actualy have rear visability? :O :O :O :O :O Is that a, a... a bubble canonpy? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif Looks awsome.

uppurrz
05-28-2009, 07:54 AM
Some Mosquitoes used NO, so it can't be said it was not compatible with the Merlin. The P-51H used ADI.

JG53Frankyboy
05-28-2009, 08:14 AM
Originally posted by uppurrz:
Some Mosquitoes used NO, so it can't be said it was not compatible with the Merlin. The P-51H used ADI.

the allied engines didnt need NO because the allied side had , in general, the superiour supercharger technolegy to give the engines full power at higher altidudes IIRC

and AFAIK MW50 and water injection worked in general similar.
So, at least P-47s, F4Us and F6Fs had water injection.

Kettenhunde
05-28-2009, 08:33 AM
Just been thinking about MW50 and Ntrous Oxide after reading Manus thread, and wondered why the Allies never used it?


It has already been pointed that some Allied aircraft did use Nitrous Oxide. They had about as much success as the GAF with it.

Water injection as used on Allied engines is Alcohol-Einstpritzung as used by the GAF. There is not any real difference in the systems.

All the best,

Crumpp

Xiolablu3
05-28-2009, 09:26 AM
Didnt the Spitfire and typhoon (in fact all the RAF aircraft) just use high boost in its engines for short periods rather than using MW50?

Kettenhunde
05-28-2009, 09:39 AM
Didnt the Spitfire and typhoon (in fact all the RAF aircraft) just use high boost in its engines for short periods rather than using MW50?


That is correct. Just like the BMW801D2 in the FW-190A8, the Spitfire and Typhoon engines just used a higher manifold pressure.

All the best,

Crumpp

No41Sqn_Banks
05-28-2009, 09:54 AM
In "Spitfire: The History" by Eric B. Morgan and Edward Shacklady there is a section about the experimental use of water injection with early Merlin engines.
Unfortunatly I can't access my copy at the moment.
IIRC they tested it with Merlin II/III but engine lifetime was reduced from 100hrs to 10hrs and they abandoned the idea in favour of higher octane fuel.

danjama
05-28-2009, 11:12 AM
I'm pretty sure the use of water injection or methanol would shorten the life of any engines significantly, because of much higher temperatures and stress on the engines, meaning more regular servicing and more chance of breakdown while under load.

What interests me, is what shortens the life of an engine more, use of the above mentioned injections, or higher boost settings for regulated periods.

Any information comparing the two methods and how they effect engine serviceability would be appreciated.

Xiolablu3
05-28-2009, 11:46 AM
I'm interested too, as while the Germans didnt have large quantities of higher quality fuels at the end of the war to reach high boost pressures, so they were forced the other way.

Whereas the RAf could have chosen either way.

This suggests that boost is the best way to go, but is that really the case?

I guess for the Germans, if a planes life expectancy in 1944 is 4 or 5 sorties, then you are not going to be bothered if the engine only has 15 hours combat life.

Po-cat
05-28-2009, 12:06 PM
It's also worth bearing in mind that Luftwaffe aircraft typically used lower octane fuels (look for the '87' in the yellow triangle), whereas the Allies were using significantly higher octane fuels (100 springs to mind - can anyone confirm?)....Did I read somewhere that some P-47s used 150 Octane at some stage?

I'm sure there are exceptions to both the above statements, but you get the picture ;o)

Could it also be the case the the Luftwaffe had a need for better climb performance for day-bomber interception?

na85
05-28-2009, 12:09 PM
Originally posted by Po-cat:
It's also worth bearing in mind that Luftwaffe aircraft typically used lower octane fuels (look for the '87' in the yellow triangle), whereas the Allies were using significantly higher octane fuels (100 springs to mind - can anyone confirm?)....Did I read somewhere that some P-47s used 150 Octane at some stage?

I'm sure there are exceptions to both the above statements, but you get the picture ;o)

Could it also be the case the the Luftwaffe had a need for better climb performance for day-bomber interception?

Octane number is not the sole determinant of a fuel's performance. The German 87-octane fuel was far superior in anti-knock performance than allied fuels with 87 octane.

Plus many countries use different methods of determining octane number, and thus different ratings for the exact same fuel are possible.

uppurrz
05-28-2009, 02:09 PM
One also has to remember that the Germans used lean mixture when rating their fuel and the Allies used rich mixture when rating their fuel. Late war German C3 fuel had a PN number of around 130-140.

from Wiki

Definition of octane rating

Octane rating of a spark ignition engine fuel is the detonation resistance (anti-knock rating) compared to a mixture of iso-octane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. By definition, iso-octane is assigned an octane rating of 100 and heptane is assigned an octane rating of zero. An 87-octane gasoline, for example, possesses the same anti-knock rating of a mixture of 87% (by volume) iso-octane and 13% (by volume) n-heptane. This does not mean, however, that the gasoline actually contains these hydrocarbons in these proportions. It simply means that it has the same detonation resistance as the described mixture.

Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn rather than explode.

Buzzsaw-
05-28-2009, 03:11 PM
Salute

Basic Allied fuels during WWII were rated:

European Theater

100/130
100/150

Pacific

100/130
115/145

Allied aircraft using the British developed 100/150 fuel initially had issues with deposits forming at low speed, low boost, lean condition cruise speeds. These problems were solved by running the aircraft periodically at high boost and rich conditions, and the use of alternate spark plugs.

The American developed 115/145 fuel solved all these problems, and allowed boost levels as high as 90 inches MAP on the Packard Merlins.

German fuels as mentioned, had a different method of indicating their rating, but however you notate their ratings, these fuels never did allow the same higher levels of boost in German engines which were common in Allied aircraft engines. Hence the requirement for MW-50.

We can't know the exact composition of German fuels, since the synthetic refineries which produced them were destroyed, and the exact formulas lost.

Here is an Allied analysis of C3 Fuel:

http://img14.imageshack.us/img14/6999/5031120875325c3octane19.jpg

Kurfurst__
05-28-2009, 03:13 PM
Originally posted by danjama:
I'm pretty sure the use of water injection or methanol would shorten the life of any engines significantly, because of much higher temperatures and stress on the engines, meaning more regular servicing and more chance of breakdown while under load.

Actually water injection very considerably lowers the temperatures of the engine - as water evaporates, it takes heat away with it.
What shortens engine life is the stress on the engine, but this comes from the higher power output.


What interests me, is what shortens the life of an engine more, use of the above mentioned injections, or higher boost settings for regulated periods.

Neither - its the increased mechanical stress on the engine resulting from higher power output.
If you think it over, we don't have any meaningful pressures here as far the boost alone is concerned - late war German engines went up to around 2 ata, and the rubber tyres on my car are pumped to 2.1-2.2 ata...


Any information comparing the two methods and how they effect engine serviceability would be appreciated.

Increasing power will reduce the engine life due to higher mechanical loads, regardless how you achieve it.

The other factor was spark plugs. From what I understand both using ADI/MW-50 (same thing) reduced spark plug life; fouled, burnt out spark plugs could indirectly result in shorter lifespan of the engine, causing cut out or pre-ignition.

It would seem to me that higher boost achieved with 150 grade fuel on the Merlins was more detrimental; with it spark plug life dropped to just about 7-8 hours, which meant that spark plugs had to be changed after every one or two long range escort sorties.

The G-14's manual for MW 50 boost states three kind of regular maintenance issues that need to be performed while using MW 50:
a, Spark plug life is reduced to 15 to 30 hours of operation
b, The filter for the MW system had to be replaced after 6 hours of operation
c, After each 10 hours of operation, the viskosity of the lubricant had to be checked with (these two latter were a rather simple task though)

Running the engine at lower power with 150 grade fuel would lead to spark plug fouling and eventually, and had to be opened up every 15 minutes or so to prevent lead deposits building up.

From that point of view ADI/MW 50 was more practical, since it was
a, only injected during maximum output, but not during cruise
b, it actually cleaned the spark plugs.

Overall the practicality is a mixed affair. ADI/MW-50 had two pluses

a, It gave considerable internal cooling to the engine, making larger radiators unneccessary. ie. at the 1800 HP output with MW50 the DB 605 actually produced less heat than at 1300 HP without MW-50.
b, It cooled down the charge before entering the combustion chamber, effectively enabling high manifold pressures without pre-ignition and knocking.

The downside was, of course, the added weight, this was about 100 kg, some 70 kg of it being the 70 liters of water/methanol liquid carried (which naturally decreased as it was used up), and the 30 kg weight 115 liter light alloy container (on the 109G/K, this latter was evened out by the fact that it was installed in the place of a 32 kg light alloy armor behind the fuel tank, yet the light alloy tank full of booster liquid had more or less the same effect in slowing down bullets).

OTOH, Allied engines used intercooler installations for effectively the same reason and effect as MW 50, for charge-cooling and enabling higher manifold pressures, but without providing internal cooling to the engine. The intercooler and the intercooler radiators themselves were fairly heavy as well, and the radiator also added drag to the aircraft.

Kurfurst__
05-28-2009, 03:23 PM
Originally posted by Buzzsaw-:
We can't know the exact composition of German fuels, since the synthetic refineries which produced them were destroyed, and the exact formulas lost.

Composition of German fuels are fairly well known, actually, see: http://www.kurfurst.org/Engine...tml#Supply_and_Specs (http://www.kurfurst.org/Engine/Fuel/German_fuel_specifications_and_production.html#Sup ply_and_Specs)


Originally posted by Buzzsaw-:
German fuels as mentioned, had a different method of indicating their rating, but however you notate their ratings, these fuels never did allow the same higher levels of boost in German engines which were common in Allied aircraft engines. Hence the requirement for MW-50.

Its an odd statement; the composition of German C-3 fuels (introduced in 1940, then being equivalent of 130 grade fuel) was changed in late 1942, and this was equivalent of Allied 150 grade - which did not appear in service use for until 1944. See: http://www.kurfurst.org/Engine...ropsch_Archieves.pdf (http://www.kurfurst.org/Engine/Fuel/mof-secth_Testing_and_Evaluating_Products_via_Fischer-Tropsch_Archieves.pdf)

MW 50 was choosen because German designers probably saw it more attractive for fighter than installing intercoolers for charge cooling; and their other attractive qualities, namely, internal engine cooling.

Buzzsaw-
05-28-2009, 03:32 PM
Salute Kurfurst

If the German C3 fuel was in fact equivalent to the Allied higher grade fuels, then why is it the case that German boost pressure never matched that used by Allied aircraft engines?

And why is it that hp/litre output for Allied engines was so much higher than German?

For example, the Merlin 66 was capable of nearly 2200 hp on 27 cubic litres displacement, whereas the best the DB605 could manage on 35 cubic litres displacment was 2000 hp?

http://www.spitfireperformance.com/merlin66hpchart.jpg

Chart courtesy of Mike Williams Spitfire Performance site:

http://www.spitfireperformance.com/spittest.html

Kurfurst__
05-28-2009, 03:49 PM
Originally posted by Xiolablu3:
I'm interested too, as while the Germans didnt have large quantities of higher quality fuels at the end of the war to reach high boost pressures, so they were forced the other way. Whereas the RAf could have chosen either way.

It was not really a matter of choice for either side, but a logical result of the aero engines they had at the start of the war.

The British settled with the 27 liter Merlin, the Germans with a 33-35 liter engines (Jumo 211/213, DB 601/605).

The mechanics of an engine's output are simple: all things - boost, rpm, CR - equal, you will never produce the same amount of output in a 27 liter engine as with a 35.7 liter engine. So you need to start to compensate for the lack of displacement, and the most straightforward way is to increase boost: increase boost by 50%, power will increased by roughly 50%.
It effectively means pumping 50% more air into the engine, to burn 50% more fuel. Its very effective, on the short term.

In the long run however, small displament makes life difficult, and an uphill battle.

If you need, say, 1.25 ata boost to produce the same power as the other guy does at 1 ata with his bigger displacement engine, it will mean that you will need 1.5 times higher octane rating, too.

You will need a more powerful supercharger to deliver this 1.25 ata, and running superchargers takes away power from the propeller (and no small amounts - the Griffon 65 for example used some 600(!!) HP to drive a supercharger), though fuel still needs to be burned to produce that power. Say you end up with 10% power loss, so you have to increase boost the 1.375, to make up for it.

Running your engine at 1.375 ata also means that you will need significantly better quality fuel. The supercharger, while compressing the air to 1.375 ata pressure, will heat it up, and makes more likely that it will pre-ignite and damage the engine.

At this point, you are producing the same power, but already with worser fuel economy, since the other guy doesn't burn any fuel yet to drive a supercharger.

But now he decides to, installs a supercharger increasing boost to 1.25 ata; if you want to match him, you need to increase boost by 25%, to some 1.70 ata. You will need an even more powerful supercharger, taking even more power from the engine, even better fuel, and as the process goes on, after a while you just can't get even better fuel, so you will need to cool down the charge by either adding an intercooler, or using ADI. Since you need supercharging at all times to provide sufficent power, ie. even during cruise to provide a high cruising speed, you will probably opt for an intercooler, that is always there. However, the intercooler again adds weight, and drag, which needs to counterweighted, by even more engine output... and for that, you again need higher boost, an even more powerful supercharger that consumes even more power, a larger (and heavier) propeller to absorb the power.

And since with all that you again made your fuel economy worser, suddenly you find that the fighter which could go to 600 miles at the start of the war, can now only go to 400 miles with the same fuel... so you need to add extra fuel to the aircraft. Doh, more weight again, need to increase power, need to increase boost, need bigger supercharger, need better fuel, need larger intercooler, and a larger radiator that keeps my 2000 HP engine reasonable cool while actually produces 2600 HP (and the heat associated with 2600 HP), but some 600 HP of this is being spent on driving a monstrous sized supercharger, and that 600 HP requires fuel to burn the same... doh, I am down again at 400 miles range. Need add more fuel...

It is a vicious, accelerating spiral.

K_Freddie
05-28-2009, 03:51 PM
That Corsair looks like it's photoshopped..
It seems to have an exact ww2 FW canopy including head-shield armour plate ??.
It might be a vertical lifting canopy as there are no horizontal rails to slide it backwards

Very unusual, but if it is so... so what http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

If I'm not mistaken,, his rudder correction is wrong for the current flaps and angle of attack..
http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif

Buzzsaw-
05-28-2009, 03:56 PM
Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Xiolablu3:
I'm interested too, as while the Germans didnt have large quantities of higher quality fuels at the end of the war to reach high boost pressures, so they were forced the other way. Whereas the RAf could have chosen either way.

It was not really a matter of choice for either side, but a logical result of the aero engines they had at the start of the war.

The British settled with the 27 liter Merlin, the Germans with a 33-35 liter engines (Jumo 211/213, DB 601/605).

The mechanics of an engine's output are simple: all things - boost, rpm, CR - equal, you will never produce the same amount of output in a 27 liter engine as with a 35.7 liter engine. So you need to start to compensate for the lack of displacement, and the most straightforward way is to increase boost: increase boost by 50%, power will increased by roughly 50%.
It effectively means pumping 50% more air into the engine, to burn 50% more fuel. Its very effective, on the short term.

In the long run however, small displament makes life difficult, and an uphill battle.

If you need, say, 1.25 ata boost to produce the same power as the other guy does at 1 ata with his bigger displacement engine, it will mean that you will need 1.5 times higher octane rating, too.

You will need a more powerful supercharger to deliver this 1.25 ata, and running superchargers takes away power from the propeller (and no small amounts - the Griffon 65 for example used some 600(!!) HP to drive a supercharger), though fuel still needs to be burned to produce that power. Say you end up with 10% power loss, so you have to increase boost the 1.375, to make up for it.

Running your engine at 1.375 ata also means that you will need significantly better quality fuel. The supercharger, while compressing the air to 1.375 ata pressure, will heat it up, and makes more likely that it will pre-ignite and damage the engine.

At this point, you are producing the same power, but already with worser fuel economy, since the other guy doesn't burn any fuel yet to drive a supercharger.

But now he decides to, installs a supercharger increasing boost to 1.25 ata; if you want to match him, you need to increase boost by 25%, to some 1.70 ata. You will need an even more powerful supercharger, taking even more power from the engine, even better fuel, and as the process goes on, after a while you just can't get even better fuel, so you will need to cool down the charge by either adding an intercooler, or using ADI. Since you need supercharging at all times to provide sufficent power, ie. even during cruise to provide a high cruising speed, you will probably opt for an intercooler, that is always there. However, the intercooler again adds weight, and drag, which needs to counterweighted, by even more engine output... and for that, you again need higher boost, an even more powerful supercharger that consumes even more power, a larger (and heavier) propeller to absorb the power.

And since with all that you again made your fuel economy worser, suddenly you find that the fighter which could go to 600 miles at the start of the war, can now only go to 400 miles with the same fuel... so you need to add extra fuel to the aircraft. Doh, more weight again, need to increase power, need to increase boost, need bigger supercharger, need better fuel, need larger intercooler, and a larger radiator that keeps my 2000 HP engine reasonable cool while actually produces 2600 HP (and the heat associated with 2600 HP), but some 600 HP of this is being spent on driving a monstrous sized supercharger, and that 600 HP requires fuel to burn the same... doh, I am down again at 400 miles range. Need add more fuel...

It is a vicious, accelerating spiral. </div></BLOCKQUOTE>

Despite your attempts to change the subject from power output to fuel economy, (which was not a problem for the Allies, they had lots of fuel, unlike the Germans) the performance question is clear, the Merlin's output per litre was higher because the availability of high octane fuel, thus the opportunity to run higher boost.

And as far as range is concerned, the 109 had no significant advantages over the Spitfire, and as we all know, lagged far behind the P-51.

K_Freddie
05-28-2009, 04:01 PM
Originally posted by Buzzsaw-:
And as far as range is concerned, the 109 had no significant advantages over the Spitfire.
But you know that didn't make a difference as the Germans were 'playing a home game', similar to the Brits in BoB... Here's where the Merlin P51 made the difference.
http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

stalkervision
05-28-2009, 04:04 PM
Originally posted by K_Freddie:
That Corsair looks like it's photoshopped..
It seems to have an exact ww2 FW canopy including head-shield armour plate ??.
It might be a vertical lifting canopy as there are no horizontal rails to slide it backwards

Very unusual, but if it is so... so what http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

If I'm not mistaken,, his rudder correction is wrong for the current flaps and angle of attack..
http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif


# www.museumofflight.org/aircraf...-f2g-1-super-corsair (http://www.museumofflight.org/aircraft/?goodyear-f2g-1-super-corsair)


http://www.museumofflight.org/files/imagecache/full_page/TMOF_Goodyear+F2G-2+Corsair_P1.jpg


Goodyear F2G-1 Super Corsair

Big, robust, and fast, the Goodyear F2G was often referred to as the "Super Corsair" for good reason. Designed and produced by Goodyear rather than Vought, the F2G design mated the Corsair airframe to Pratt & Whitney's huge R-4360 engine rated at 3,000 horsepower. Other changes were a bubble canopy and a taller vertical stabilizer with auxiliary rudder to compensate for the engine's extra torque. Some 418 F2Gs were ordered, but only five F2G-1s and five folding-wing "dash twos" were manufactured.

Ironically, the F2G Corsair made its name in the peacetime world of air racing. Navy pilot Cook Cleland obtained four surplus F2Gs and substantially modified one, clipping six feet off the wingspan. He won the 1947 Thompson Trophy race at 396 mph while two years later the Super Corsairs scored a clean sweep with Cleland, Ron Puckett, and Ben McKillen taking the top three spots. In ten starts over three years the F2Gs scored two wins, two seconds, and a third-place finish.

The Museum's F2G-1 Corsair, Navy Bureau of Aeronautics number 88454, was delivered in 1945. As the first production F2G-1, it spent most of its career at the Navy Air Test Center at Patuxent River, it then went into storage at Norfolk, Virginia, the Corsair with only 246 hours flight time.

In the early 1960s Navy title passed to the Marine Corps Museum at Quantico, Virginia. Following display aboard the aircraft carrier Intrepid during New York's bicentennial observance in 1976, the F2G was barged back to Norfolk. Subsequently, the museum traded the Corsair and a Douglas Skyraider to Doug Champlin in exchange for a Dauntless dive bomber. Champlin kept the Corsair at Enid, Oklahoma, until he opened his museum in Mesa, Arizona, in 1981, when former Thompson Trophy racer Ron Puckett flew the F2G to Falcon Field. Subsequently the rare Corsair came to Seattle with the rest of the Champlin collection in 2003.

www.airrace.com/CorsairStatusList2.html (http://www.airrace.com/CorsairStatusList2.html)

K_Freddie
05-28-2009, 04:08 PM
I could spend all my life in these museums http://forums.ubi.com/images/smilies/25.gif

Ah!! just seen the rest of your post...
That is a mean looking plane.. an extension of sorts like the Dora !!

stalkervision
05-28-2009, 04:12 PM
Originally posted by K_Freddie:
I could spend all my life in these museums http://forums.ubi.com/images/smilies/25.gif

Ah!! just seen the rest of your post...
That is a mean looking plane.. and extension of sorts like the Dora !!

what a bird. http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

Kurfurst__
05-28-2009, 04:17 PM
Originally posted by Buzzsaw-:
Salute Kurfurst

If the German C3 fuel was in fact equivalent to the Allied higher grade fuels, then why is it the case that German boost pressure never matched that used by Allied aircraft engines?

Several reasons. First of all, German engines used much higher compression ratios than Allied engines - ie. compare the later war 8.5:1 compression ratio of the DB 605D with the 6:1 of the RR Merlin/Griffon. Its almost 50% higher. In the end, the actual pressure at the time of ignition was very similiar.

Secondly, larger volume engines can simply produce the same amount of power with less boost...

Whenever possible, the Germans increased CR (6.9 - > 7.5 -> 8.5:1), but they also kept increasing the revs(2400 -> 2800), the boost (1.42 -> 1.98ata) and the displacement (33-> 35 liters) to increase output.

Increasing compression ratio yields better fuel economy (less fuel/weight needs to be carried for the same range). It also increasing the need for high quality fuels, and does not increase power as profoundly as a same % of increasing boost, but unlike increasing boost pressure, which is only effective increasing power below the rated altitude, increasing CR increases power at all altitudes.

Given how much supercharging it needs to increase output at altitude, and the long term benefits in terms of development, I understand why the Germans choose high swept volume and high CR.

Take a look at the Bf 109 and the Spitfire.

At the start of the war, they had about the same output of horsepower, about the same performance. The Spit was slightly heavier.
At the end of the war, they still had about the same performance, but the Spit was much heavier.

The Spitfire's fuel capacity was increased by ~50%, yet it's range was decreased by ~30%, the 109's fuel capacity remained the same, yet it's range was increased by 50%.


And why is it that hp/litre output for Allied engines was so much higher than German?

For example, the Merlin 66 was capable of nearly 2200 hp on 27 cubic litres displacement, whereas the best the DB605 could manage on 35 cubic litres displacment was 2000 hp?[/QUOTE]

Its simple, the Merlin was highly supercharged, and its designers could boast with a meaningless brochure figure (HP/litre), whereas the practical comparison the engine size and weight reveals that they managed to produce same output with smaller displacement engine, which with all of its accessories (intercooler, supercharger, intercooler radiators etc) needed to achieve that, was considerably heavier than the larger displacement DB engine, and ate through fuel barrels like a Marine going ashore... ie. 196 gallons of fuel/hour at +25 to produce ~2000 HP on the Merlin 66, vs. 143 gallons of fuel / hour at 1.98ata to produce ~2000 HP on the DB 605D.

The highest boost pressure cleared for the Merlin 66 was +25 lbs and approx. 2000 HP output, same as the later war DB 605D; if we want to include planned/toyed with/tested etc. boost pressures that did not see service, ie. +28/2.3ata, the picture does not change much. The altitude output of the DB engine was better somewhat, but then of course the Merlin 66 was medium altitude engine, and there existed high altitude Merlins, like the 70, which were more comparable to the DB.

Kurfurst__
05-28-2009, 04:29 PM
Originally posted by Buzzsaw-:
Despite your attempts to change the subject from power output to fuel economy, (which was not a problem for the Allies, they had lots of fuel, unlike the Germans) the performance question is clear, the Merlin's output per litre was higher because the availability of high octane fuel, thus the opportunity to run higher boost.

Fuel had little to with it; the DB 605A was capable of running at some 1550 PS output, on 87 octane fuel in 1942, when the Merlin 61, with 100 octane fuel, was rated the same.
However DB run into some problems, which had nothing to do with the fuel, but the (faulty) design of the lubricating system, and the engine could simply not take more than about 1400 PS until 1943 (lubrication of the bearings went to nil due to foaming at highers powers), even if they would give it 1000 octane fuel.

As far as fuel economy not a problem for the Allies, supplying it to airfields certainly wasn't (neither was it a problem for the Germans at that time), the problem was that while early war Spitfires had a range of some 595 miles, the mid-war ones had only some 420-450 miles range, and could not escort the bombers, since regardless of how big drop tanks they hanged on it, as it had to fight and then return on the fuel it carried internally, and that was enough for only ~430 miles, sans any high output being involved. They had to wait for the P-51, which was simply large enough to carry the necessary amount fuel.


And as far as range is concerned, the 109 had no significant advantages over the Spitfire, and as we all know, lagged far behind the P-51.

I guess it depends on the definition of 'significant'. The 109F/G/K is somewhere midway between the mid-war Spit and the P-51.

http://i38.photobucket.com/albums/e133/Kurfurst/109G_51B_Spit_Tempest_RANGE.jpg

Xiolablu3
05-28-2009, 04:45 PM
You are forgetting the Spitfire VIII.

3rd most produced mark of Spitfire....

Also the MkVII.

Both had more range than the Bf109.

The VIII's were sent to the most crucial theatre, which was Malta/Africa and Italy at that time. (late 43/44). There was no real danger on the Channel front by this time, it was strongly held.

As always range 'depends'. On what mark of aircraft and what its carrying, and how fast its flying. I have seen many quotes of lower range for the Bf109 than in that chart, and also higher for the Spitfire IX.

Depends which chart you read and who is telling.

Kurfurst__
05-28-2009, 05:06 PM
Originally posted by Xiolablu3:
You are forgetting the Spitfire VIII. 3rd most produced mark of Spitfire....

Lets see - by mid-1943 (up the end of June), 24 of them produced with M66, 169 with M63...


Originally posted by Xiolablu3:
Also the MkVII.

14 produced with M61 by mid-1943, 18 with M64...


Both had more range than the Bf109.

Yes, its true (depending on who's chart you look at - I can start waving charts for the 109G showing 725/1200 miles range, same as the Mk VII/VIII), its only they weren't available but to a couple of Squadrons per theatre which wasn't going to challenge the LW over its own turf, when it was most needed, before the Mustang and drop tanks for the P-47 arrived.

Thing is, for the Germans operational needs, the range of the 109 was more than adequate, and there was no need to make it longer (except for a couple of very long range recce versions) and there were plenty of them, flying, with the Jagdgeschwadern, on all fronts.


As always range 'depends'. On what mark of aircraft and what its carrying, and how fast its flying. I have seen many quotes of lower range for the Bf109 than in that chart, and also higher for the Spitfire IX.

The ranges I have seen for the Mk IX are 420 miles, 434 miles (Mk IXLF) and 450 miles. Ranges I have seen for the 109G are 595 miles, 615 miles (twice) and 725 miles, all on internal fuel and economic cruising.

Bremspropeller
05-28-2009, 05:07 PM
And as far as range is concerned, the 109 had no significant advantages over the Spitfire, and as we all know, lagged far behind the P-51.

Which was caused by differences in the airframe... http://forums.ubi.com/images/smilies/disagree.gif

ImpStarDuece
05-28-2009, 05:11 PM
Originally posted by Kurfurst__:

The Spitfire's fuel capacity was increased by ~50%, yet it's range was decreased by ~30%, the 109's fuel capacity remained the same, yet it's range was increased by 50%.


Don't know about the 109, but for the Spitfire, that commentary bends the facts quite severely:

Spitfire Mk I (Merlin II): 85 Imp gallon, max range at cruise of 540 miles,
Spitfire IX (Merlin 66) 85 Imp gallon, max range at cruise of 435 miles (20% decrease in range);
Spitfire Mk VIII (Merlin 66): 120 Imp gallon (40% increase in capacity), max range at cruise of 740 miles (37% increase in range);
Spitfire Mk XIV (Griffon 65): 120 Imp gallon (40% increase in capacity), max range at cruise of 460 miles (15% decrease in range)
Spitfire XXI: (Griffon 65): 120 Imp gallon, max range at cruise of 490 miles (10% decrease in range).

All information from the various Spitfire data sheets.

Kurfurst__
05-28-2009, 05:22 PM
Originally posted by ImpStarDuece:
Don't know about the 109, but for the Spitfire, that commentary bends the facts quite severely:


O RLY?

From 'the various Spitfire data sheets', I get 595 miles for the Mk I, and 460 miles for the Mk XIV - pardon me but that is 29%, oh, indeed, not 30%, what a severe bending of facts...!

Whatever, lets use your 40% increase in fuel, capacity, 15% decrease in range. Still shows the same.. the engines becoming fuel hogs.

uppurrz
05-28-2009, 05:23 PM
ImpStarDuece, are those ranges at most economical cruise?

uppurrz
05-28-2009, 06:01 PM
Originally posted by Kurfurst__:
Take a look at the Bf 109 and the Spitfire.

At the start of the war, they had about the same output of horsepower, about the same performance. The Spit was slightly heavier.
At the end of the war, they still had about the same performance, but the Spit was much heavier.

Take off weight of a Spitfire I with 2 blade prop - 5875lb
Take off weight of a Bf109B - 4398lb

Take off weight of a Spitfire XIV - 8475lb
Take off weight of a Bf109K-4 - 7412lb

weight with no external stores.

weight increase of the Spitfire - 8475/5873 x 100 = 142%

weight increase of the 109 - 7412/4398 x 100 = 168%

As can be clearly seen, the 109's weight increased much more than did the Spitfires.

Waldo.Pepper
05-28-2009, 08:52 PM
You guys really have just got to get this book.

http://img.photobucket.com/albums/v516/WaldoPepper/book/cover.jpg

While it may not be terribly detailed it is just incredibly broad. I seem to refer to it all the time!

From page 65

"The two injection systems did, however, carry with them weight penalties. The MW-50 installation for the Messerschmitt 190G-14 weighed about 300 pounds, complete with 26 gallons of water-methanol. The GM-1 installation fitted to some versions of the Messerschmitt 109G weighed about 670 pounds, with 16 gallons of nitrous oxide. 'Right thinking' Rolls-Royce engineers would argue that having containers of various odd concoctions, with pipes running all over the place, was a poor substitute for a supercharger of the correct capacity. On the other hand the Germans had no fancy high octane fuels on which to run highly supercharged engines on the Rolls-Royce pattern; they had to do the best they could using fuels of 100 octane rating and lower."

danjama
05-28-2009, 09:08 PM
Interesting to boring in one page.

edit: apart from waldos post above, that was pretty good.

Kettenhunde
05-28-2009, 10:25 PM
You guys really have just got to get this book.

The information is good but dated and incomplete.

Buzzsaw-
05-28-2009, 10:29 PM
Originally posted by Kurfurst__:

The highest boost pressure cleared for the Merlin 66 was +25 lbs and approx. 2000 HP output, same as the later war DB 605D; if we want to include planned/toyed with/tested etc. boost pressures that did not see service, ie. +28/2.3ata, the picture does not change much. The altitude output of the DB engine was better somewhat, but then of course the Merlin 66 was medium altitude engine, and there existed high altitude Merlins, like the 70, which were more comparable to the DB.

Not even close. Read the engine chart I posted. The Merlin 66 was approved for +28, but there was no need to use that boost, the Allies were comfortably outperforming the Germans with +25.

Your claims for 1.98 boost for the DB605 are suspect, since in fact, only a single Staffel ever used that level of boost on a test basis, and its use was discontinued because of engine problems. 2.3 is a complete fantasy.

All of the late war German plans for uber 109's were conditional on fuel supplies and manufacturing standards which did not exist. As they said themselves in their planning:

"...if the abovementioned measures can be actually be materialized for series production."

Meanwhile the RAF had switched its fighters in Europe over to 100/150 octane completely.

Kettenhunde
05-28-2009, 11:05 PM
The Merlin 66 was approved for +28, but there was no need to use that boost,

That does not make much sense. The engine had some severe difficulties at +25 with the fuel, where do you see it approved for +28 during the war?

An engine chart and test is not approval, it just a test or a calculation.

The 100/150 grade was used operationally for ~3 months in the 2nd TAF after being tested and withdrawn from the ADGB test units. It is not some common everyday miracle tonic thrown into airplane engines.

It screws them up in fact this is noted in the numerous reports gathered at that popular site. Fouling plugs and decreased reliability probably seems inconsequential at your desk reading about it.

It is a sphincter tightening experience in a real airplane that can kill you. That is why the fuel was unpopular with so many squadrons in the three months it was in use.

The Germans and the Allies all had the same problems with high performance special fuels. It is a limitation of the engine technology not the fuel technology.

All the best,

Crumpp

Kurfurst__
05-29-2009, 04:20 AM
Originally posted by Buzzsaw-:
<the usual stuff>

Its always a pleasure to try to discuss something with you, BS. I thought it would be possible to discuss the quirks of piston engine development, why this or that path was followed, but I see you jumped on your usual bandwagon, and spouting out nonsense again, so I see no need to continue discussing with you any further. It strikes me as a waste of my time.

JtD
05-29-2009, 04:52 AM
Assuming two identical engines with the same peak pressure in the cylinder, but one with high boost low compression, the other with low boost high compression, the latter will have the higher peak temperatures in the cylinder. It will benefit more from a water injection than the other one. Or, given the natures of the British and German design philosophies as outlined by Kurfürst, the German engine would benefit more. I think it's one of the reasons the Germans used it while the British didn't.

danjama
05-29-2009, 06:48 AM
http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif @ sphincter tightening experience

Kettenhunde
05-29-2009, 06:49 AM
JtD, That makes perfect sense. Thanks for bringing that up.

All the best,

Crumpp

Xiolablu3
05-29-2009, 12:22 PM
Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Xiolablu3:
You are forgetting the Spitfire VIII. 3rd most produced mark of Spitfire....

Lets see - by mid-1943 (up the end of June), 24 of them produced with M66, 169 with M63...


Originally posted by Xiolablu3:
Also the MkVII.

14 produced with M61 by mid-1943, 18 with M64...


Both had more range than the Bf109.

</div></BLOCKQUOTE>

As I said in my post which you forgot (http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif) to quote, latter half of 1943 and into 1944. That doesnt include 'early 1943'.. However you say there were about 200 around in the first half of 1943? Wow I didnt think there would have been that many. Thats a lot of aircraft, over 8 squadrons worth. I thought the MkVIII was a late'43 aircraft up until now...ty.

Most of the most important, front line overseas squadrons were equipped with the Mk VIII through the mid '43 to early '44 period.

I recommend Duncan Smiths book 'Spitfire into Battle'. It tells of that theatre.

http://en.wikipedia.org/wiki/W._G._G._Duncan_Smith


http://ecx.images-amazon.com/images/I/41FZPSPVSQL._SL500_AA240_.jpg

Italy and the Med were the most important theatre for the West Front mid-war period right up to D-day. (June 1944)

Buzzsaw-
05-29-2009, 01:35 PM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">The Merlin 66 was approved for +28, but there was no need to use that boost,

That does not make much sense. The engine had some severe difficulties at +25 with the fuel, where do you see it approved for +28 during the war?

An engine chart and test is not approval, it just a test or a calculation.

The 100/150 grade was used operationally for ~3 months in the 2nd TAF after being tested and withdrawn from the ADGB test units. It is not some common everyday miracle tonic thrown into airplane engines.

It screws them up in fact this is noted in the numerous reports gathered at that popular site. Fouling plugs and decreased reliability probably seems inconsequential at your desk reading about it.

It is a sphincter tightening experience in a real airplane that can kill you. That is why the fuel was unpopular with so many squadrons in the three months it was in use.

The Germans and the Allies all had the same problems with high performance special fuels. It is a limitation of the engine technology not the fuel technology.

All the best,

Crumpp </div></BLOCKQUOTE>

Your claims are not supported by the facts.

The initial issues with 100/150 octane fuel were dealt with by changing spark plugs, ******ing the ignition slightly, and installing heavier gauge bolts on the exhaust manifolds.

See this memo detailing the experience of AIR DEFENCE GREAT BRITAIN Fighter Squadrons using the fuel and +25 boost:

http://www.spitfireperformance...0grade/appendixa.pdf (http://www.spitfireperformance.com/150grade/appendixa.pdf)

The memo notes that use of the fuel "...is satisfactory under service conditions and gives rise to no real problems in either handling or operation."

ADGB discontinued use of the fuel because at this stage in the war, there were problems in supplying Squadrons based in Europe with 100/150 fuel, not because use of the fuel and higher boost was a problem. Because there was a continual interchange of aircraft between these Squadrons and those based in Great Britain, administratively it was easier to revert to 100/130 fuel till the supply situation could be resolved with the opening of suitable ports. At that point USAAF 9th Air Force aircraft were using 100/130 octane, and therefore standardizing on that grade would simplify supply.

Anyone who has even moderate knowledge of this period of the war, ie. September 1944, will know that all Allied military on the continent were still being supplied through the Mulberry Harbours at the D-Day beachheads, the supply lines stretched all the way from those harbours to the front. Supply of fuel was so strained that the advance of several American and British divisions had to be halted and their divisional trucks diverted to resupply purposes.

Even though this temporary reversion to 100/130 octane and +18 boost occurred, all ADGB Mustangs continued to use 100/150 octane fuel in their aircraft. These aircraft flew over the continent, trouble free.

In late November as the port of Antwerp and other French ports were coming into service as Allied supply centers, it was determined that shipment of two separate grades of fuel could begin, this was started, and ADGB and 2nd TAF were ordered to resume use of 100/150 as of late November 1944 as per this memo:

http://www.wwiiaircraftperformance.org/2taf150_112044.gif

2nd TAF then used 100/150 fuel from that point till the end of the war, more than 5 months, NOT the three months you claim. In total, ADGB Spitfires used 100/150 octane for 5 months from April of '44 to early September '44, and then from December '44 to May '45.

Only one RAF wing suffered issues with the fuel during that 2nd period, that being 126 Wing, (four Squadrons) equipped with the new Spitfire XVI's, which had the Packard Merlin 266 engine. These reported issues with backfires. Since these American manufactured Merlins, which were different in design, did not have the replacement alternate hotter sparkplugs available, the decision was taken to reduce boost to +18.

No other Spitfire Squadron, (or Tempest/Typhoon/Mustang Squadron) found it nessesary to reduce boost, and the standardized use of 100/150 octane fuel and higher boost continued in all aircraft using the standard Merlin 66's which equipped Spitfire IX's or the Griffon engines which equipped the Spitfire XIV.

All material courtesy of Mike Williams Spitfire site:

http://www.spitfireperformance.com/spittest.html

mhuxt
05-29-2009, 03:34 PM
"It all went into storage. Just prove it didn't"

http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

Po-cat
05-29-2009, 04:31 PM
And all I said was 'this Halibut was good enough for Jehovah!'

Seriously, this has been a real education, and it's good to see such well informed discussion.
Long may it continue http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

So....Avtur?

(retires to safe distance...)

Andy

Kettenhunde
05-29-2009, 10:22 PM
There is no need to speculate and I refuse to argue about this silliness.

The history in the RAF is well researched with exception of one small fact. The fuels withdrawal in April of 1945 is overlooked as I am sure the webmaster does not have these facts in their possession.

What they do have they are nice enough to make available to all. The presentation is kind of confusing in the article with all the fuel depot and supply side information. The Technical staff input is a not very well researched either so we don’t much about specific difficulties that prevented widespread adoption.

It is enough and the operational use is spelled out for us without the need to guess.

As I understand the history of 100/150 grade use in the Merlin 66 Spitfires, we have two squadrons used in during service trials as part of the ADGB approved in May 1944. The fuel was withdrawn from use when the anti-diver campaign was concluded.


Early in March, 1944 Service Trials with Spitfire IX L.F aircraft operating at + 25 lbs./sq.in boost and using 150 grade fuel were commenced at Milfield.


the success of the trials at Milfield, Wittering and Southend, the trials were extended on the 3rd may 1944, to include all aircraft in No.1 and 165 squadrons, at Predannack.

The fuel was still undergoing trials until August 1944.


All pilots reported most favorably on the value of the high boost pressures obtainable with 150 Grade Fuel, however, Technical Staff felt that before the fuel was introduced on a large scale that the causes of backfires must be established and that at least 12 engines should complete 200 hours each. 3

http://www.wwiiaircraftperform.../150-grade-fuel.html (http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html)

In September 1944 the trials were over and it was withdrawn from ADGB use.


To continue to use 150 Grade Fuel in operational Squadrons is undesirable for the following reasons:-

http://www.wwiiaircraftperform.../18-sept-44-doc.html (http://www.wwiiaircraftperformance.org/150grade/18-sept-44-doc.html)

So it was in service trials for quite some time due to maintenance difficulties without general operational approval.

It next was in operational use in the 2nd TAF in February 1945 but was again withdrawn from service in April 1945 after a series of fatal accidents.


The shipping of fuel from Antwerp started on 2 January, 1945:


On the 5 February 1945, J.H Houghton Brigadier General, U.S.A. Director of Supply, reported that the R.A.F on the Continent were using 100/150 grade fuel:


Senior Intelligence Officer of 126 (RCAF) Spitfire Wing, 2 TAF, noted in his daily operational summary on 20 April 1945 after the crashes of two Spitfires; "The incidents followed a number of engine problems that were attributed to the introduction of 150-grade fuel in early February. Pilots mistrusted it, and were no doubt relieved when the AF brass decided to revert to 130-grade. The vast majority of pilots, I'm sure, were beginning to wonder if the additional seven pounds of boost they got from 150-grade fuel were worth the price being paid."[11]

-Berger, Monty and Street, Brian Jeffrey.Invasion Without Tears. Toronto, Canada: Random House, 1994 (1st ed) ISBN 0-394-22277-6

In summary, the fuel had a few airplanes undergoing service trials with operational use limited to ~3 months in the 2nd TAF only.

All the best,

Crumpp

Kettenhunde
05-29-2009, 10:48 PM
No wonder there is some confusion. I just noticed that on the main article page it says this about the fuel:


Following successful testing, the Spitfire IX's Merlin 66 was cleared in March 1944 to use +25 lbs, obtainable with 150 grade fuel. 29 In early May, No. 1 and No. 165 Squadrons comprising the Predannack Wing, were the first to convert their Spitfires to +25 lbs boost and employ 150 grade fuel on operations.

Well that tells me that the RAF was up and running and using 100/150 grade outside of any testing.

http://www.wwiiaircraftperform.../150-grade-fuel.html (http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html)

However if you read the references we get this:


Early in March, 1944 Service Trials with Spitfire IX L.F aircraft operating at + 25 lbs./sq.in boost and using 150 grade fuel were commenced at Milfield. Nine aircraft were involved, six being fitted with S.U. Fuel Injection Pumps and the remaining three with standard Stromberg carburetors. The trials were extended in the first week of April to include an aircraft with an S.U. Pump at the A.F.D.U. and twelve standard Spitfire IX L.F. aircraft at No. 17 A.P.C Southend.

It says that the testing began in March with 9 airplanes and was extended in April to include another 12 aircraft.

21 Spitfire Mk IX Merlin 66 using 100/150 grade is all we have flying in service trials.


In view of the success of the trials at Milfield, Wittering and Southend, the trials were extended on the 3rd may 1944, to include all aircraft in No.1 and 165 squadrons, at Predannack

In May the testing was expanded to include all of the aircraft in two squadrons in the ADGB for the service trials.


Attached and marked “B” is a summary of the trials with 150-grade fuel as at the 14th June 1944.


The trials are summarized on the 14th of June:


From the forgoing, it will be seen that pilots are impressed by the performance resulting from the use of 150-grade fuel and consider that the time is ripe for its general introduction. This view is not shared by the Technical Staff of this Headquarters, who consider that before the fuel is introduced on a large scale that the causes of backfires must be established and that at least 12 engines should complete 200 hours each, so that the effects of the high lead content of the fuel be known.


http://www.wwiiaircraftperform.../16-june-44-doc.html (http://www.wwiiaircraftperformance.org/150grade/16-june-44-doc.html)

All the best,

Crumpp

Buzzsaw-
05-30-2009, 12:31 AM
Originally posted by Kettenhunde:
No wonder there is some confusion.


There is no confusion, unless we are talking about that which exists in the minds of those who have not actually read the documents.

Your references to events in April or May of '44 are only relevant as a indication that there were issues being worked out at that time. As I noted in the document linked in my post above, by September the issues discovered earlier in the Spring and Summer had been resolved.

Your claim that only two Squadrons of Spitfires used the fuel is clearly wrong.

From the September document I linked above, whose contents you have obviously not bothered to read:

http://img189.imageshack.us/img189/1466/spitfireix.jpg

Notice the number of hours flown: 9268

Notice the number flown by No. 1 and 165: 6000

No question that No. 1 and 165 flew more hours, they were in on the initial testing. But after the difficulties were resolved, the fuel was provided to other Spit IX Squadrons for their use, hence the other 3268 hours of flying time.

But of course, not only Spitfire IX were involved. Those converted to 100/150 included the Spitfire XIV Squadrons, hence the over 2000 hours noted below:

http://img189.imageshack.us/img189/9056/spitfirexiv.jpg

Not only the Spit XIV Squadrons, there was also rather heavy use by the Mustang III Squadrons, hence the over 7000 hours listed for that aircraft:

http://img189.imageshack.us/img189/138/mustang.jpg

Not to mention the Tempest Squadrons in ADGB:

http://img189.imageshack.us/img189/4844/tempest.jpg

Plus of course, the Mosquito Squadrons also found a use for the fuel:

http://img36.imageshack.us/img36/5995/mosquito.jpg

If you are having trouble understanding that documents dated from earlier in the year are superceded by documents dated later, then there is no point in further explanation.

Buzzsaw-
05-30-2009, 12:58 AM
Originally posted by Kettenhunde:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Senior Intelligence Officer of 126 (RCAF) Spitfire Wing, 2 TAF, noted in his daily operational summary on 20 April 1945 after the crashes of two Spitfires; "The incidents followed a number of engine problems that were attributed to the introduction of 150-grade fuel in early February. Pilots mistrusted it, and were no doubt relieved when the AF brass decided to revert to 130-grade. The vast majority of pilots, I'm sure, were beginning to wonder if the additional seven pounds of boost they got from 150-grade fuel were worth the price being paid."[11]

-Berger, Monty and Street, Brian Jeffrey.Invasion Without Tears. Toronto, Canada: Random House, 1994 (1st ed) ISBN 0-394-22277-6

In summary, the fuel had a few airplanes undergoing service trials with operational use limited to ~3 months in the 2nd TAF only.

All the best,

Crumpp </div></BLOCKQUOTE>

You really seem to have trouble reading other people's posts. If you had bothered to read my posts in this thread, you wouldn't repeat your errors.

As I mentioned earlier in the thread, 126 Wing, RCAF, the reference you make above, was flying Spitfire XVI's, which had Packard Merlin 266 engines, manufactured in North America, with different sparkplugs, and different carburation from the standard Rolls Royce manufactured Merlin 66.

The Merlin 66's in Spitfire IX's had been altered for the use of 100/150 octane fuel with modified carburation, heavier exhaust manifold bolts, and hotter sparkplugs. None of these modifications would fit the Packard Merlin 266, hence when the backfire problem started, there was no immediate solution available, as Packard did not have technicians or workshops availabl in Spring '45 as Rolls Royce did during the introduction of 100/150 fuel in the Summer of 1944.

The solution was for this single Spitfire XVI equipped Wing to reduce its boost levels to +18.

NONE of the other Spitfire Wings followed suit. They had no requirement to do so, as their Spitfire IX's were not suffering the backfire problem.

Plus of course, all the Spitfire XIV, Mustang, Tempest, and Mosquito Squadrons also continued to use 100/150 octane and the higher boost.

Kettenhunde
05-30-2009, 01:02 AM
Well here is another page of the same document that does not just focus on total hours flown but rather breaks down the maximum amount in single aircraft.

It seems to agree with the conclusions of the same documents and recommendation of the Technical staff noted in the article.


All pilots reported most favorably on the value of the high boost pressures obtainable with 150 Grade Fuel, however, Technical Staff felt that before the fuel was introduced on a large scale that the causes of backfires must be established and that at least 12 engines should complete 200 hours each. 3


I think things are arranged in a very confusing manner on that website.

http://img189.imageshack.us/img189/9384/aircrafttimes.jpg (http://img189.imageshack.us/my.php?image=aircrafttimes.jpg)

http://www.spitfireperformance...june-44-attach-b.jpg (http://www.spitfireperformance.com/150grade/16-june-44-attach-b.jpg)

In summary, the fuel had a few airplanes undergoing service trials with operational use limited to ~3 months in the 2nd TAF only.

All the best,

Crumpp

Buzzsaw-
05-30-2009, 01:06 AM
Salute

Its rather humerous that Crumpp is making an attempt to downplay the amount of use of 100/150 octane fuel by the RAF and USAAF, while ignoring the fact the Luftwaffe's claimed use of 1.98 boost in the 109K4 was limited to a single Staffel on an experimental basis, a tiny fraction of the flying time put in by RAF and USAAF aircraft flying with 100/150.

Kettenhunde
05-30-2009, 01:15 AM
Crumpp says:
It has already been pointed that some Allied aircraft did use Nitrous Oxide. They had about as much success as the GAF with it.

Water injection as used on Allied engines is Alcohol-Einstpritzung as used by the GAF. There is not any real difference in the systems.

http://forums.ubi.com/eve/foru...841026957#2841026957 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2341006957?r=2841026957#2841026957)


Crumpp says:
The Germans and the Allies all had the same problems with high performance special fuels. It is a limitation of the engine technology not the fuel technology.

http://forums.ubi.com/eve/foru...241087957#1241087957 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2341006957?r=1241087957#1241087957)

All the best,

Crumpp

Buzzsaw-
05-30-2009, 01:16 AM
Originally posted by Kettenhunde:
In summary, the fuel had a few airplanes undergoing service trials with operational use limited to ~3 months in the 2nd TAF only.

All the best,

Crumpp

Once again, you are quoting an outdated document, from the early part of the process of working out the issues.

Go back and look at the total flying hours listed in the September document.

They total nearly 10,000 flying hours.

For those who don't understand how much flying time this represents, I'll do the math.

A standard RAF Squadron sortie involved 12 aircraft.

A Spitfire IX's endurance is approx. 2.5 hours. Typically though, most missions involved flight times of 2 hours. A Mustang's endurance was 3.5 hours, typically 3 hours. But lets round it off at 2.5

Divide the figure of 10,000 flying hours by 2.5 for the typical mission length, then again by 12 for the number of aircraft, and you get a total of 333 Squadron strength missions flown with 100/150 octane fuel during the period April - September '44. Or if you want, 4,000 sorties.

And Crumpp: You're still insisting this is a few airplanes undergoing service trials? Wow, those test pilots really rack up the hours... http://forums.ubi.com/images/smilies/88.gif

Sorry Crumpp, your math and your logic seems to be off.

BillSwagger
05-30-2009, 01:33 AM
i'm jumping in the middle of the discussion, here...but pertaining to original post. My knowledge of Nos systems is that they are somewhat brief by comparison to other boost systems AND require additional modifications to the engine(s) to prevent damage.
Perhaps the NO3 systems were less popular as allied boost systems because the range the pilots were flying related to the amount of WEP needed when they did get the target or meet bogies in the air.

Kettenhunde
05-30-2009, 02:52 AM
They total nearly 10,000 flying hours.



Your rationalization is only some ~700 hours short of the actual total of 9268 total hours flown Only 6000 hours were flown by the two squadrons included in the testing. Read your own clipped document on the Merlin 66 results from the trials.

The total hours do not tell us a thing about individual engine hours.

All the best,

Crumpp

deepo_HP
05-30-2009, 03:17 AM
Originally posted by Buzzsaw-:
... trouble reading other people's posts...
If you had bothered to read my posts... well, i won't say, that i had understood all of anyone, but i thought that i should bother to read.


Originally posted by Buzzsaw-:
and ADGB and 2nd TAF were ordered to resume use of 100/150 as of late November 1944 as per this memo: is that an order? looks to me like clearance, with a necessarity of previous modifications?


Originally posted by Buzzsaw-:
Read the engine chart I posted. The Merlin 66 was approved for +28 i read some test charts done with +28, but not an approval?


Originally posted by Buzzsaw-:
From the September document I linked above, whose contents you have obviously not bothered to read: still no mentioning of +28, what have i missed?


Originally posted by Buzzsaw-:
to other Spit IX Squadrons for their use, hence the other 3268 hours of flying time. how much would that be in planes x days?


Originally posted by Buzzsaw-:
I'll do the math.
... a total of 333 Squadron strength missions is that only spitfires? as i thought, that crumpp was referring to spitfire-squads?
from the quoted document, i do the math only for some 140 'Squadron strength missions'. which makes 25 'Squadron strength missions' per month. how many squadrons would be involved in those 'Squadron strength missions' in your opinion?
what about the 28-boost? i am not sure, that i got the 'september'-document right, but i found only limitations to 25, resp 21? some 'anticipations' as well, but no 'approval' at all.


Originally posted by Buzzsaw-:
why is it the case that German boost pressure never matched that used by Allied aircraft engines? oh, that's too technical... why had allies smaller displacement and less compression-ratios? how do full-throttle-heights compare and curves of staged superchargers?
so where exactly do you see the disadvantage of less power/litres?
a smaller engine surely needs higher boost to get higher power/litres to match a bigger engine in absolute power. and very well done by rolls-royce!
but where is the point you see by telling, that 2200hp for a heavier plane at less altitude is so much more desirable than 2000hp on the other one?
i find it remarkable though, how 2 different designs could be developed over 6 years to more or less equally expressed usage.

i saw xiolablu's opener as an interesting comparison between those designs. about how the performance would have been differed by the ways it was achieved.
even without (any) quality fuel, rolls-royce had it done different to daimler. even with (any) quality fuel, daimler had it done different.

so far i started reading and bother. are you sure, you have always chosen well by using 'approval', 'order' and 'proof'?
for the fuel-discussion, there perhaps wouldn't have been any war, if IG Farben hadn't had good connections.

Kurfurst__
05-30-2009, 04:29 AM
Originally posted by Buzzsaw-:
Salute

Its rather humerous that Crumpp is making an attempt to downplay the amount of use of 100/150 octane fuel by the RAF and USAAF, while ignoring the fact the Luftwaffe's claimed use of 1.98 boost in the 109K4 was limited to a single Staffel on an experimental basis, a tiny fraction of the flying time put in by RAF and USAAF aircraft flying with 100/150.

We know of at least 4 Gruppen (Wing), ie. 16 Staffeln (Squadrons) using it.
Earlier before, in Febuary 1945, II/JG 11 was testing it, that is the 2nd Gruppe (Wing) of JG 11, again, not a Staffel, but four.

http://kurfurst.org/Engine/Boo...5D_clearance198.html (http://kurfurst.org/Engine/Boostclearances/605D_clearance198.html)

Now as for 150 Grade fuel and the 2nd TAF, even on Mike's site they don't claim it was used before January 1945, and if one reads the consumption figures in NW Europe, its pretty clear it wasn't introduced in a large scale until March-April 1945 - at least in the RAF. The RAF in November estimated some 10,000 tons/month being the requirement for the 30-odd Spitfire Squadrons in the 2nd TAF, yet in January and February they consumed around 2000 tons of fuel, and in March, 7000 tons; obviously, conversion to the new fuel occured gradually.

http://www.wwiiaircraftperform...er_barrels_tons.html (http://www.wwiiaircraftperformance.org/150grade/theater_barrels_tons.html)

126 Wing (Canadian Spitfire IXs) introduced it February, 1945, for example, and it was not trouble-free:

From accounts by Monty Berger, Senior Intel Officer of 126 (RCAF) Spitfire Wing, 2 TAF:

"...he noted [in his day's (apr 20 '45) operational summary]as well that two pilots had walked away-"more or less"-with only slight injuries from wrecked and flaming aircraft at B 116 [Wunstorf, Germany]. actually, it was a miracle either man survived. flying officer F R Dennison of 411(sqn)-a Grizzly Bear from Buffalo, NY-crashed while taking off and broke his back. later in the day, flt leiutenant E B Mossing of 401(sqd), who also had his engine cut during take off, scraped his spitfire's belly tank over an obstacle and came down so hard the impact ripped it's wings off, broke the fuselage at the instrument panel and left what remained of the aircraft a mass of flames-yet Mossing "extricated himself with one bone broken in his leg"

the incidents followed a number of engine problems that were attributed to the introduction of 150-grade fuel in early feb. pilots mistrusted it, and were no doubt relieved when the AF brass decided to revert to 130-grade. "the vast majority of pilots, im sure, were beginning to wonder if the additional seven pounds of boost they got from 150-grade fuel were worth the price being paid." the matter was being dicussed at Wunstorf when, incredibly, a spark at the petrol dump ignited and two petrol bowsers containing almost two thousand gallons of the much-despised fuel burst into flames."

uppurrz
05-30-2009, 05:50 AM
Originally posted by Kurfurst__:
We know of at least 4 Gruppen (Wing), ie. 16 Staffeln (Squadrons) using it.
Earlier before, in Febuary 1945, II/JG 11 was testing it, that is the 2nd Gruppe (Wing) of JG 11, again, not a Staffel, but four.

I have yet to see any definitive proof that those Gruppen actually used 1.98ata.

There is some debate whether it is II./JG11 or 11./JG11. How many K-4s did II./JG 11 have in Feb 1945? On Jan 1 1945, they only had 11 K-4s and 38 G-14s.

DrHerb
05-30-2009, 07:56 AM
NoS is a limited supply of boost.

Turbo/Supercharging is unlimited (till you run out of gas of course).

Kettenhunde
05-30-2009, 08:04 AM
Turbo/Supercharging is unlimited

True. AFAIK, Nitrous Oxide is oxygen enrichment and I don’t see as all that useful to a turbocharged aircraft.

However even turbocharged aircraft like the P-47 benefited from knock limited performance enhancements like Water Injection.

All the best,

Crumpp

DrHerb
05-30-2009, 08:10 AM
I think Water Injection was used to cool the induction to eliminate pre-ignition (supercharging compresses air and compressed air heats up as per common knowledge)

You also lose horsepower if the induction temperature is too high AFAIK

In the end, NoS and supercharging achieves the same goal of more horsepower, its just two different methods of achieving it.

Kettenhunde
05-30-2009, 08:53 AM
I think Water Injection was used to cool the induction to eliminate pre-ignition


Yes, it raises knock limited performance.

http://www.dsmtuners.com/forum...water-injection.html (http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/222053-suppressing-knock-water-injection.html)


its just two different methods of achieving it.


Correct, Nitrous Oxide works primarily by oxygen enrichment although the nitrogen aids in cooling the charge some too.

In the thin atmosphere at high altitude the oxygen enrichment is a larger factor for a non-turbocharged engine as opposed to one that is turbocharged able to keep up the partial pressure of oxygen in the manifold.


supercharging

Keep in mind that supercharging has some benefits to a designer for a high powered piston engine air superiority fighter that turborcharging did not offer.

All the best,

Crumpp