Is the Spitfire Really Superior to the FW-190 ... continued

[Jabberwocky]

But prepare to be swarmed by Spitfire fans.

Well, I'm quite a Spitfire fan myself. British aircraft are, shall we say, my cup of tea. Bring them on, I love a good dogfight.

My last post left touching on the Merlin 61 engined Spitfire IX facing the 190A3 towards the end of 1942. The RAF had 4 squadrons fully operational with the IX by Dieppe and averaged about 2 squadrons converting to the newer version a month. Meanwhile the Luftwaffe operated 190A3/A4s and began to transition to 190A5 in mid 1943 with JG 2, JG 26 and maybe JG 56 (??) flying from France and Belgium.

By the end of April 1943 the 190A4 was in service and the 190A5 had entered production, improving the 'Butcher Bird' once again. The engine mounting was lengthened 15cm to reduce vibration and strenthen parts of the airframe. The Mw-50 Methanol/Water injection system also had a revised installation. The FW could now do approx 400-410 mph at 6000m with the Mw-50. Reports mention that there may of been a 2 minute operatonal limit imposed on Mw-50 in initial service, mostly due to overheating problems. This is contentious though as the manuals generally state 5 minutes or even ten minutes of operation per use. There was enough mixture for about 25 minutes of operation.

What the Mw-50 did was to significantly enhance the boost levels and speed of the 190, albeit for limited periods. The FW was now faster than ever, but weight creep was affecting its handeling, Kurt Tank actually developed a new wing for the A6 variant, to deal with the problem as well as to revise armament options. The 190 was always known for its very high stall speeds. It stalled at about 110-120 mph straight and level, compared to 70-80 mph in the same attitude for the Spitfire. In turns there was little if any warning of the vicious snap-stall that could develope. This made the 190 unsuited to traditional low speed dogfighting, Tank having realised that high speed would keep pilots alive better than sharp turns. Tank actually wanted higher wingloadings so that he could increase the speed of the 190.

In parallel with the improvements to the 190 the Spitifre was also seeing upgrades. Most noticably the Merlin 61 was fitted with an improved Bendix-Stromberg carburettor and other modifiactions and turned into the excellent Merlin 66/70/71 family. The Merlin 66 appeared about March 1943, alowing the Spitifire to increase its horsepower and boost levels in almost all regiemes of flight, as well as reducing crankcase loading with a heavier weighted crankshaft.

The Spitifre IX operating a Merlin 66 at +18lbs was between 15-20 mh faster below 11,000 feet than the Spitifre IX with a Merlin 61 at +16lbs. Up high there was very little difference in speeds, but down low the Sptifire was finally catching up with the 190. Its rate of climb was now much better at low altitude, particularly in the L.F. clipped wing versions of the Spitfire IX, which accounted for around half of all Merlin 66 production. Given how close the A3 had been to the Merlin 61 Spitfire IX in terms of low to medium level performance, the A4/A5 now had even less envelopes where it was ascendent. The RAF also deployed around 200 Merlin 70/71 high altitude versions of the Spitfire IX. It could reach around 415-418 mph at 27,000 feet, making it markedly better than the Fw190 above 20,000 feet.

Add to this the conversion of Spitfire V ariframes for lew level duties. The rather unkind epithat of "clipped, cropped and clapped" was added to them. Clipped, as in the wings, cropped as in the supercharger impellers were cut back for low alt usage and clapped, as in clapped out old airframes. However, these modifications turned the Spitfire V into a very useful low level fighter. Adding a Merlin 50M or 55M and running the engine at 18lbs boost meant that the formerly outclassed Spitfire V was now challenging the Fw190 at low altitudes.

Compared to a 'classic' Spitfire Vb/c with a Merlin 45/46 the L.F. version was a menace down low. With clipped wings and modified airframes (whip aerial, revised mirror rairings, removing the carburettor ice guard) it was up to 20 mph faster than the Vb/c on the deck. At full throttle height of 6000 feet a clipped L.F. V could make close around 350-360 mph. In 1943 some Spitfire Vbs also had their 'fishtail' type exhaust stubs replaced with multi-ejector stacks, the better aerodynamics and thrust generated by the new exhausts adding a further 5 mph down low.

With clipped wings a Spitfire V L.F. was only some 10-15 degrees per second slower in roll than a Fw-190. So, at the Fw-190s peak roll rate of about 165 degrees/second, the Spitifre was less than 10% slower in the roll. Only a few Allied fighters ever out rolled the 190, the P-38L with boosted alierons, the Mustang and Tempest are the only ones that come to mind, and even they only did so at high speed. At such low altitudes the traditiona FW flick over and dive was not effective and the FWs generally had to perform a shallow nose over followed by a serise of high speed zoom climbs to escape.

The little Spitfire V could now hope to compete with the 190A5 at low altitude. With a Merlin 50M the Spitfire climbed over 4,500 feet per minute until 5,000 feet and maintaned a 4,000 fpm climb until 10,000 feet. After this performance fell off rapidly however due to the cropped supercharger impeller on the M serise Merlins. With a Fw 190A4/A5 running at 1.42 ATA [highest cleared boost for the A5, used in mid 43 - early 44] the Spitfire V held roughly level pegging in speed from about 5,000 to 10,000 feet. Above or below these heights the Fw190 generally outran the Spitfire V but could not outclimb it at any height below 10,000 feet.

With the combination of Spitfire IX H.F. above 30,000 feet, Spitfire F/L.F. at 20,00 feet and Spitfire L.F. Vb/c at 5000-10000 feet the Spitfires now had the numbers and the all altitude abilities to deal with the 190 effectively.

More later, I'm just warming up to this. I knew there was a reason I had kept all the Rechelin and RAE reports on my HD!

 

[Nonskimmer]

Good stuff!

 

[KraziKanuK]

By the end of April 1943 the 190A4 was in service and the 190A5 had entered production, improving the 'Butcher Bird' once again. The engine mounting was lengthened 15cm to reduce vibration and strenthen parts of the airframe. The Mw-50 Methanol/Water injection system also had a revised installation. The FW could now do approx 400-410 mph at 6000m with the Mw-50. Reports mention that there may of been a 2 minute operatonal limit imposed on Mw-50 in initial service, mostly due to overheating problems. This is contentious though as the manuals generally state 5 minutes or even ten minutes of operation per use. There was enough mixture for about 25 minutes of operation.

Jabber I believe some of your info is incorrect. The MW50 was tested on A-4s but was never installed in operational A-5s. What was used was the injection of C3 fuel which allowed the A-5 to use 1.62ata for a minute or two and under 1000m. This limit was later increased. The first A that could use MW50 operationally was the A-8 but again the C3 fuel injection was the preferred method.

For more info on the 190A contact, http://www.white1foundation.org/


Faber's captured A-3 ran rough and was down on power because it used British fuel which was not compatable with German C3 fuel. C3 had additives which the British fuel lacked.

Do you have any info on this JG56?

 

[alejandro_]

According to

http://www.faqs.org/docs/air/avfw190.html#m2

Jabberwocky is right:

The Spitfire IX did help even the odds over the long run, but Focke-Wulf was still churning out better versions of the Butcher Bird. The "FW-190A-4" went into production in late 1942, the primary improvement being the addition of an "MW-50" water-methanol power boost system for the BMW-801 engine. The MW-50 injected water into the engine's cylinders to raise the engine's redline limit for a short period of time. The methanol was mainly intended as anti-freeze.

Regards.

 

[KraziKanuK]

Don't believe everything you read on the net alejandro.

This is what your link says about the 109K:

The initial production models were the "Bf-109K-2" and the "Bf-109K-4", with deliveries beginning in October 1944. The Bf-109K-2 was fitted with the DB-605ASC or DB-605DC engine, with GM-1 nitrous oxide boost as standard, and three-gun armament, featuring an MK-108 or MK-103 Motorkanone and twin MG-151/15 cowling guns. The Bf-109K-4 was identical, but featured cockpit pressurization.

Note the MG151/15. The K was only fitted with the MK108. A modified MK103, the MK103M, was tested but never installed. There was no K-2s produced though they were scheduled to start production at Erla, WNF and MTT Regensburg in Feb 1944. In March 1944 the decision was made to standardize on the K-4.

On the 190A with MW50, please look at these A.L. Bentley drawings and tell me where the MW50 tank was fitted on the A-5. http://www.albentley-drawings.com/fw190a_f_g.htm

Bentley did his drawing using Focke-Wulf documentaion as well as a/c inspections.

 

[Hop]

4) Significantly better dive, both in absolute speed and dive handling. The 190 could simply run away from the Spitfire in a dive if the pilot found himself in trouble. At 500 mph true the control were described as "although slightly heavier, are still remarkably light"

At higher altitudes the Spitfire had a dive speed advantage due to i's thin wing. The Spitire had about the highest Mach limit of any WW2 prop fighter.

7) Superior climb. The Fw-190 climbs at a higher m/sec and higher speed than the Spitfire Vb until very high altitude (27,000 feet or higher)

The Spitfire V had a better climb rate than the early 190s, up to at least the end of 1942.

The AFDU report on Faber's 190 says differently, but the AFDU made an error in their tests, running their 190A3 at a higher power setting than the Germans allowed. In fact, the RAF used what was the German's 3 minute rating as a 30 minute rating, and used a 3 minute rating that the Germans didn't use on the A3.

In short, the AFDU overboosted their captured 190.

I can document this if you want proof, but it's quite clear in the AFDU report as well, where they say there is evidence the engine has been derated. (they adjusted the engine to run at it's "full" rating even though this was higher than the Germans allowed)

Cannon ammunition went from 60 prg to 120 rpg.

This is also the case for most Vs as well. The Vc had 120 rpg to begin with, many Vbs were refitted with the Vc wing as they came in for overhaul.

3) The 190 posses superior acceleration below 23,000 feet. Above this height the Spitfire has a very slim margin, which increases with altitude.

Even the AFDU, who were overboosting their 190, found the accelertion to be roughly similar (the 190 has an acceleraion advanage except at altitudes where the Spitfire has a speed advantage, or some such iirc)

Against a 190 A3 or early A4 running the correct boost the Spitfire IX should have an acceleration advantage in most cases.

7) The Spitfire IX climbs better than the 190. The gap is marginal below 20,000 feet but increases rapidly after this point.

Again, this is due to the AFDU overboosting their 190, at the correct rating the Spitfire has a significantly better climb rate.

10) The Spitfire IX did lessen the pilots workload but as I'm not a pilot I can't really comment as to how much.

The interlinked controls meant the pilot set the throttle, mixture was already automatic, the rpm was set according to the throttle setting. I'm not sure when the interlinked controls came in, though. But note even without the interlinked control, the Spit had a constant speed prop, automatic boost conrol, and automatic mixing. That gave 2 power controls, one for throttle, one for rpm, and they were usually operated simultaneously.

So, in mid-1942 the absolute superiority of the 190A is replaced by a neck and neck horse race with the Spitfire IX.

I'd broadly agre with that, with the proviso that the Spitfire was easier to fly, and easier to get the best out of.

And you've missed some things ou of your list, eg handling, the Spitfire had much more forgiving handling, the 190 had dangerous stall charaacteristics.

The 190A received a boost when Mw-50 is introduced in late 1942, with the 190A4 and slightly lengthened 190A5.

MW50 may have been used operationaly on low level A4 jabos, it was not in widespread use, and was not used in fighters.

With a Fw 190A4/A5 running at 1.42 ATA [highest cleared boost for the A5, used in mid 43 - early 44]

That's the rating the AFDU used for their test of Faber's 190 back in August 1942, which is why their findings on the 190 needed to be treated with caution.

Faber's captured A-3 ran rough and was down on power because it used British fuel which was not compatable with German C3 fuel. C3 had additives which the British fuel lacked.

The [possibly] higher octane rating of C3 at this time would allow higher boost, it didn't confer more power at the same settings.

In fact Faber's 190 had more power than it did in German service, because the RAF used 1.42 ata, 2700 rpm as the 3 minute rating, when it was actually limited to 1.35 ata, 2450 rpm

The AFDU used 1.35 ata, 2450 rpm as the 30 minute rating, the Germans used 1.28 ata, 2350 rpm

So what the Germans consider emergency power the AFDU used as a climb setting, and as emergency setting they used far more than the 190 was cleared for.

 

[Hop]

With the sole exception of the Spitfire XIV, that could have some parity with the Butcher Bird, no Spitfire ever could tangle with the A series of the Fw 190; the scenario for the Spitfires gets even worse during the second half of 1944 when facing the "long nose" D version and the final model in the evolution of the Focke Wulf: the Ta 152.

Udet, I'll espond with a post every bit as full of facts, sourced information and evidence as you've posted:

The FW190 couldn't hope to compete with the Spitfire IX, it was completely outclassed by the British plane.

 

[Jabberwocky]

I'm a big Spitfire fan and most of my information on the FW comes from the Faber 190A3 tests and the USAAF and USN comparative tests carried out in 1943. I'd usually be rooting for the Spitfire but early on there is no doubt in my mind that the Air Ministries conclusion that the "FW190 is the best all round fighter in the world today" was correct.

While I'll accept that the Faber tests are skewed (particularly down low) because of the British running at 1.42 ata, I still think that they are a very good general guide to the perfroance and handling of a mid 1942-1943 190. They will give higher climb and level speeds than the 1.32 ata tests. However, the British never pushed the 190 into 1.42 boost for aything longer than 2 minutes.

The Faber tests states quite clearly that the 190 could outclimb the Spitfire at all altitudes. Specifically, point 49 states that

"The climb of the Fw190 is superior to that of the Spitfire VB at all heights. The best speeds for climbing are approximately the same, but the angle of the FW is steeper. Under maximum continious climbing conditions the climb of the FW is approximately 450ft/min. better up to 25,000 feet."

Point 50 of the same test states that;

"With both aircraft flying at high cruising speed and then pulling up into a climb, the superior climb of the FW190 is even more marked"

1.32 ata will knock some, but not all, of that climb advatage away. The 190 definately zoom climber far better than the Spitfire.

The same tests compare the Spitfire IX with the 190A3. Point 61 states that;

"The FW190 is faster than the Spitfire IX in a dive, particularly in the initial stage. This superiority is not as marked as with the Spitifre VB"

The 190 had a higher wing-loading and a smaller wing. Like the Spittfire it also had quite a thin wing. Standard LW tactics for disengaging fighter combat was to flick roll and invert and dive for home using their birds superior dive acceleration and capabilities. The LW recieved a rud shock when it came up against the P-47 as all of a sudden it found itself being outdived.

The comparative acceleration tests of a P-38F, Spitifre IX at 16lbs and a 190A4 have the 190 outaccelerating the Spitfire by about 200 yards initailly and then both evening off.

As for the Spitfire IX definately being a better fighter than the 190, well that is a HIGHLY contentious statement, and depends on what time you make the judgement against what type of 190. I've lurked here a while and I've seen you in other forums Hop so I know I'm not going to change your mind on this. But, before getting the Merlin 66 I feel that you are wrong. At most a Merlin 61 engined Spitfire IX had level pegging and I think that the 190 was a touch better in fulfilling its roles. Down low (below 15,000 feet) I would pick the 190A over almost any Spitfire IX variant, with the exception of a clipped wing L.F. IXe or a +25lbs boosted version.

And you were right about the 190A4/A5 not mounting Mw-50 in large numbers. While the ENGINES had the capacity to use it it wasn't standard installation until the 190A8. The 190A5 could, and did, mount the 115litre tank for the Mw-50 though and it was likely used in some numbers as it was an easy and available field modification (and remembering all the 190 and 109 field mod designations will be the death of me).

I only think that the A serise was surpassed clearly when the Spitfire XI/XVI started to used 25lbs boost, just prior to D-Day.

One thing that we all forget though is the Sptifire XII, the low level, Griffon III or Griffon IV engined version. First flying in squadron strength in January/February 1943 it was more than a match for the 190 at low altitudes. Here is where the British get their revenge, with an excellent high/low perfromance combination. Only 100 were built but initial testing showed that the XII was the best low altitude Spitfire version until the +25lbs L.F. IX came along. Production airframes of the XII (particularly the last 60 birds with the Griffon IV) climbed better, rolled faster and handled better than the IX. It saw service with 2 squadrons from very early 1943 until late 44/early 45 when both transitioned to the XIV.

 

[KraziKanuK]

Hop, are you saying that an engine with fouled plugs, which the A-3 had, would develop the same power as an engine with un-fouled plugs? The plugs fouled because the British fuel was not formulated to be used in the 801, which the C3 was. It has nothing to do with octane rating.

For more/better info ask Crumpp.

Green and Swanborough in their 190 book say the boost was reduced to 1.35 in order to conserve engine life as the A-3 was so much more superior to the Spit V. They, in their technical description of Faber's a/c from the RAE report, have a table that shows only 1.35ata being the max boost. 1.35 gave 1595hp @ 2500' and 1455hp at 18000'.

Are you saying the A-9, of which some 1800 were produced, with 2000hp could not 'compete' with 25lb boost Spit IXs?

 

[KraziKanuK]

Jabber, the 115l tank could not be mounted in the A-5 as a /R5 since there was now way to get it into the fuselage > the hatches were too small. Also when the A-8 mounted the tank, the area had to be reconfigured from the previous models.

Even when fitted to the A-8, it carried C3 since C3 injection was the preferred method of getting more power.

 

[Hop]

Are you saying the A-9, of which some 1800 were produced, with 2000hp could not 'compete' with 25lb boost Spit IXs?

Perhaps I should have put a smiley on my last post. It was intended as an answer to Udet's opinion, and was simply the opposite of his opinion, that the Spitfire can't compete with the 190A. It wasn't meant as a serious reply.

Hop, are you saying that an engine with fouled plugs, which the A-3 had, would develop the same power as an engine with un-fouled plugs?

If you're running it beyond it's full power rating, yes.

The RAE tested the 190 more thouroughly, they got considerably better climb figures out of it than FW did, even at almost the same ratings.

Green and Swanborough in their 190 book say the boost was reduced to 1.35 in order to conserve engine life as the A-3 was so much more superior to the Spit V.

The real reason is that until the exhaust was chromed the engine suffered badly from overheating, and I believe it had some other problems as well.

They, in their technical description of Faber's a/c from the RAE report, have a table that shows only 1.35ata being the max boost. 1.35 gave 1595hp @ 2500' and 1455hp at 18000'.

Yes, the RAE, who tested after the AFDU, stuck to the correct ratings, although they believed the full rating was as much as 1.5 ata.

But the AFDU used 1.42 ata 2700rpm as the emergency rating, 1.35 ata, 2450 rpm as the 30 minute rating.

I'd usually be rooting for the Spitfire but early on there is no doubt in my mind that the Air Ministries conclusion that the "FW190 is the best all round fighter in the world today" was correct.

Before the appearance of the Spit IX I'd agree.

While I'll accept that the Faber tests are skewed (particularly down low) because of the British running at 1.42 ata, I still think that they are a very good general guide to the perfroance and handling of a mid 1942-1943 190. They will give higher climb and level speeds than the 1.32 ata tests. However, the British never pushed the 190 into 1.42 boost for aything longer than 2 minutes.

They didn't run any of the planes at maximum power for more than 2 minutes, though.

For example, they conducted all climb tests at what they believed was climbing power. For the Spitfire, that meant the 1 hour rating. But for the FW, which they thought was allowed to use 1.42 ata, they actually used emergency power as the climbing rating.

So the climb tests against the Spitfire actually show the results of the Fw 190 running at emergency power against the Spitfire running at climbing power.

When you compare German tests of the Fw190 against British tests of the Spitfire, the Spitfire, even the V, clearly climbs better.

The Faber tests states quite clearly that the 190 could outclimb the Spitfire at all altitudes. Specifically, point 49 states that

"The climb of the Fw190 is superior to that of the Spitfire VB at all heights. The best speeds for climbing are approximately the same, but the angle of the FW is steeper. Under maximum continious climbing conditions the climb of the FW is approximately 450ft/min. better up to 25,000 feet."

There's two problems with that. Firstly, as already noted, the AFDU were running the 190 at emergency power, the Spitfires at climbing power.

Also, the best climb speeds were not that similar, the 190 climbed better than the Spitfire V at higher speeds. The Spitfire definately had a better climb angle.

I believe the AFDU were climbing the 190 at fairly high speeds, and trying to follow it with the other aircraft. This from Lucky 13, by Hugh Godefroy, who was the Spitfire pilot in those tests:

"With a higer wing loading than the Spitfire, the 190's maximum rate of climb was attained at an air speed of about 240 miles an hour. The Spitfire IXB's maximum rate of climb was attained at 160 miles an hour. Thus, if you were foolish enough to try to follow the 190 in full throttle climb at the same angle, you would soon find out that he was above you. On the other hand, if you pulled away and held the Spitfire at an airspeed of 160, you would climb at a much steeper angle and end up with a height advantage."

They were wrong on the 190 climb speed, of course, it's best climb was actually about 170 - 180 mph, similar to the Spitfire IX. But because it had a speed advantage over the Spitfire IX at low levels, the higher the speed you climb, the better the relative climb of the 190.

That goes even more so for the 190 vs Spitfire V, of course.

The 190 definately zoom climber far better than the Spitfire.

Yes.

The same tests compare the Spitfire IX with the 190A3. Point 61 states that;

"The FW190 is faster than the Spitfire IX in a dive, particularly in the initial stage. This superiority is not as marked as with the Spitifre VB"

The 190 had a higher wing-loading and a smaller wing. Like the Spittfire it also had quite a thin wing. Standard LW tactics for disengaging fighter combat was to flick roll and invert and dive for home using their birds superior dive acceleration and capabilities. The LW recieved a rud shock when it came up against the P-47 as all of a sudden it found itself being outdived.

Godefroy again has a slightly different take on that ("Jamie" was flying the 190 in the tests):

"If Jamie followed the favorite German technique of flicking over on his bank and going straight down, he would pull away from me in the first two or three thousnd feet. After that the Spitfire IXB could gradually catch him."

The comparative acceleration tests of a P-38F, Spitifre IX at 16lbs and a 190A4 have the 190 outaccelerating the Spitfire by about 200 yards initailly and then both evening off.

I'm not sure whether the acceleration tests were run at climbing power or maximum power, but either way the 190 was still being overboosted. If at climbing power for the other planes, the 190 was running at emergency power, if all were at emergency power, the 190 was at 1.42 ata, 2700 rpm, instead of 1.35 ata, 2450 rpm.

As for the Spitfire IX definately being a better fighter than the 190, well that is a HIGHLY contentious statement, and depends on what time you make the judgement against what type of 190.

Just to make it clear, that wasn't a serious suggestion. At least, I think the Spitfire IX was slightly better than 190A series, but I'd consider both planes closely matched.

 

[vanir]

The MW50 was tested on A-4s but was never installed in operational A-5s. What was used was the injection of C3 fuel which allowed the A-5 to use 1.62ata for a minute or two and under 1000m. This limit was later increased. The first A that could use MW50 operationally was the A-8 but again the C3 fuel injection was the preferred method.

I know warbird details less than you guys, but I know engine characteristics pretty okay.
Obviously this C3-injection raised octane rated fuel delivery. Does precisely the same thing as water injection (MW-50), that is, lowers the knock rating at a given rpm. This allows you to either use more boost or higher rpm at the same boost (longer emergency power running and that sort of thing). Engine knock stops high performance engines dead, it shuts down their power production if operation within its limits is sustained, and it can literally rattle the motor apart, hole pistons or snap conrods if sustained even further.
If C3 injection is not nitrous oxide and it's not water injection, the only other thing it could be is octane booster additives.
Water injection is better for the engine...but with higher octane rated fuel you can play with the mixture settings and even though you're going burn out the valves, really get some short term grunt. The motor will be coming out after a few runs, if it's still in one piece.
Just thought I'd mention, I don't think this C3 injection would've been the preferred method by the engine itself. Water injection really improves supercharger efficiency (giving more dynamic boost without having to change the static settings).

the 115l tank could not be mounted in the A-5 as a /R5 since there was now way to get it into the fuselage > the hatches were too small. Also when the A-8 mounted the tank, the area had to be reconfigured from the previous models.
Even when fitted to the A-8, it carried C3 since C3 injection was the preferred method of getting more power.

That sounds like why pre-A8's probably used a fuel additives injection, as in it sounds logical to me. However if the A8 was reconfigured to mount the 115l MW-50 tank, considering it is a far better, safer system of reducing engine knock ratings for more power production, why wouldn't it have used it?
I'd speculate any notation where "C3 injection" was preferred to "MW-50" would be for difficulties relating to fitment. It is better to keep a standardised octane and use water injection than it is to use fuel additives. The same supercharger settings give more cylinder fill for a start...


Just a few thoughts.

 

[plan_D]

Excellent initial posts, Jabberwocky.

I think the basic agreement among the most of us is the Spitfire V was inferior to, Spitfire IX equal to and Spitfire XIV superior to the Fw-190A. More detailed information is starting to come out and your posts were great.

Welcome. 8)

 

[DerAdlerIstGelandet]

That is pretty much what everyone agrees to here.

 

[KraziKanuK]

vnir,

C3 injection was injected simular to MW50, at the blower.

C3 is the German designation for their 'high test' fuel. B4 is the designation for 'regular' grade fuel. 190s with the BMW801 required C3 grade fuel.

A couple of links that might interest you,

http://www.fischer-tropsch.org/Tom Reels/Linked/A5464/A5464-0638-0654 Item 6A.pdf
http://www.fischer-tropsch.org/prim...45_45_sec2.htm#Composition and Specifications

 

[Soren]

Welcome to the Forum Vanir

And good posts btw

 

[Soren]

And welcome to you to Jabberwocky

 

[vanir]

Thanks for the links, Krazi.
I see the octane (R+M/2) of C3 sits at around 110 (ie. approx. 130 rated and 95 min motor method), compared to the 104 octane used in the Merlin 25, whereas the B4 resides at closer to 97-100 octane.

In an engine enhancement, increased power can be gained by raising the dynamic compression ratio but this limits rpm, or by increasing intake/exhaust flow dynamics but this sends torque production up the rev-range (both through valve timing), either way this increases cylinder pressures and/or temperatures under the same boost. Frequently as an engine undergoes development, valve timing and dynamic compression ratios will continually be varied in conjuction with balanced port flow rates.
Predetonation can occur at high performance tunings and this can be countered by either higher octane fuels or water injection.

In an aircraft engine this means it'll start knocking at high power settings unless you're either using a higher octane fuel (C3), or switch on a water injection system (MW-50).

This brings me to my point of confusion.
A higher octane fuel doesn't lower cylinder temperatures, it just burns at a higher one.
Water injection actually lowers the cylinder temperatures, allowing standard grades of fuel to be used without predetonation.
Blower efficiency is directly proportional to temperature, water injection lowers blower temperatures, with many models actually increasing boost at a given boost setting (you set it for say, 1.35 ata and it delivers at the cylinders as if it was say, 1.4 ata and does so with less chance of predetonation than it did before you started modifying anything, this effect is more pronounced with roots-type blowers and works more like vastly improved intercooling on impeller-types, allowing ones with greater island-cfm to be fitted instead).

When racing engineers put together an engine, it is always preferable to build one for standard grade octanes. Motors last longer. Most race tracks use pump grade petrol these days for endurance racing.

So I don't at all understand why C3 injection would be preferrable to MW-50, except on limited run, early production test engines whilst the bugs are being sorted out.

 

[DerAdlerIstGelandet]

MW-50 anyhow was not meant for long use anyhow. It never was a replacement for a supercharger.

 

[Hop]

So I don't at all understand why C3 injection would be preferable to MW-50, except on limited run, early production test engines whilst the bugs are being sorted out.

It's preferable because it means you don't require a separate tank and plumbing for the MW50, which means less weight, or you can carry extra fuel in the place of the MW50, which means more range.

It also doesn't have the corrosive effects on the engine MW50 had.

Blower efficiency is directly proportional to temperature, water injection lowers blower temperatures,

So, as I understand it, did C3 injection.