Re: Papers: Meredith Effect and RR Merlin carburator T.O.
- From: "Geoffrey Sinclair" <gsinclairnb@xxxxxxxxxxxxx>
- Date: Tue, 27 Jun 2006 20:25:27 +1000
"Eunometic" <eunometic@xxxxxxxxxxxx> wrote in message
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Geoffrey Sinclair wrote:
"Eunometic" <eunometic@xxxxxxxxxxxx> wrote in message
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Geoffrey Sinclair wrote:
"Eunometic" <eunometic@xxxxxxxxxxxx> wrote in message
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(Incidently in research for this post I cam across the point that
the
Me 109F may have been an extra-ordinarily efficient aircraft that
degenerated only as too much bulk in the form of armament,
equipemnt,
armour and engines size was added, the Me 109F achieving 416mph on
less
power than either Spifire or P-51
The big killers for airspeed were the large bulges added in order to
fit 13mm machine guns on the G series. Another source of extra
drag was the increased size of the landing gear tyres. This meant
small bulges in the upper wing surface but probably more drag was
produced by the fat the tail wheel was no longer retractable, it would
not fit into the cavity.
By the way the claim the Bf109F was a more efficient airframe than the
P-51
is really wrong. The RFA figures for the P-51 show this, see below.
The airframe pulled about the same speed out of the same power as the
earlier allison engine machines albeit with a smaller airframe that had
less capacity for fuel, armour and future growth.
What I like about the above claim is the way the top speed figures
which are disputed are assumed to be correct.
Also when the Bf109F is supposed to do a remarkable speed at 16,000
feet "it is remarkable because it did so in the thick dense atmosphere"
The P-51A did its top speeds at even lower altitudes.
The G series (except for the G-0/G-1) had a longer stroke longer bored
DB605 engine instead of DB601. This engine was deeper but not longer
and drove the evolution of the bulges as much as the ammunition
requirements of the bigger guns in the 109-G6. It was the equivalent
of the Grifon. Neither the Me 109G1 with the DB601 nor the Me 109G-2
with the new DB605 had the bulges as it did not have the 13.2mm MG 131
machine guns. The other factor was the 'oversized' supercharger
impellor in the Me 109G-6 AS and Me 109G-6 ASM and DB605D of the K
series.
The main "bulges" were to allow the fitting of the 13mm machine guns.
Then came the bulges in the upper wing to allow for larger undercarriage
tyres. At least this is the ranking in terms of size.
The original bulges were a pair of intake scoops to provide cooling air
for the exhausts and spark plugs for the new engine of the G series.
So the new engines drove the 'original' bulges as much as the guns;
just as I said.
You really do not have much of clue about this do you.
Go look at the photographs and try and pick the intake scoops near
the spinner, versus picking the fuselage bulges to accommodate the
machine guns.
In between the two, time wise, came the bulges in the wings to fit
larger landing gear main wheels and the fixing of the tail wheel.
It's simple really: the DB605 was a deeper engine than the DB601
Bulges are the requirement for a wider engine, not a deeper one.
The larger undercarriage was fitted officially from the G-4 onwards,
but often retrofitted to earlier G models.
It was enlarged yet again for K series, though the K lost the amunition
dump bin in the chin
Yes, as far as the undercarriage was concerned.
The DB605 is the equivalent of what Griffon?
Yes Geoffrey, like in the IQ test:
When did you receive your failing grade?
The Merlins, Griffons, and DB engines each formed a family, with very
different arrangements between the British and German engines.
Merlin is to Griffon as DB601 is
the DB605:
So now we are comparing the difference of the British engines to
each other, then comparing the difference of the German engines
to each other.
Both the bigger engines obtained much of their volume
increase through a substantially longer bore though the Merlin was much
smaller than the DB601 and the ancestor of the Griffon was not the
Merlin but the "R"engine.
So equivalent means swept area, at least as far as DB605 versus
Griffon is concerned.
Griffon 6, 1,850 HP at 2,000 feet, on 1,800 pounds weight?TheØ griffon was a 36.7 litre engine, the DB605 was 35.7 litres.
Griffon 61, 2,035 HP at 6,000 feet, on 2,000pounds weight?
Griffon 72, 2,245 HP at 9,000 feet?
Griffon 83, 2,340 HP at 750 feet?
So the difference in swept volume was 2.8%.
So a 2.8% difference means equivalence, at least when it is in
the German favour it seems.
The DB605A, B, C emergency rating 1,475 HP at sea level on 1,650
pounds weight.
The AM (Methanol injected A engine) emergency rating of 1,800 HP
at sea level.
The AS (A engine with bigger supercharger) emergency rating
1,435 HP at sea level.
The D, fitted with the bigger supercharger as standard.
If the engine designation has a C in it then the engine is using 96
octane, in effect the same as the allied 100 octane.
Nope. C3 fuel is nothing like allied 100 octane either early American
or British. It is either 92/110 and increased to 96/125 around mid
1944 coincident with a large increase in permisable boost pressures and
powers for the DB605 and BMW801.
http://www.fischer-tropsch.org/Tom%2...0Item%206A.pdf
http://www.fischer-tropsch.org/prima...ecificat ions
Neither of these URL's load for me, they appear to have been edited.
The USN report on the site notes the German 95 grade fuel roughly
corresponded to the allied 130 grade fuel, with poorer lean mixture
performance.
The interesting thing is the Germans rated the fuel at 95 or 96.
By the way 96/125 versus 100/130 is apparently a big difference
at the moment. Around 5%, when comparing engines however
2.7% in swept volume is equivalent.
Like the language.
Around late 1944 British analysis of residual fuel in captured or
downed Luftwaffe aircraft started to show that C3 or "Green dyed"
fuel performance numbers increased to around 95/125. This is a well
short of 100/130.
Yes folks, 5% less performance numbers is well short. Here anyway
because it appears to be needed. The Germans need poor fuels so
their aircraft can be more wonderful.
Prior to that the fuel had been analysed at 92/110
and 95/118 (approx). Some of the samples of fuel had RON octane
ratings of 95.5 or even 96 which is most certainly a case of the German
fuel plant trying to exceed the official standard of 95. Presumably
this is the origin of the 96 octane figure often quoted. So we have a
fuel officially rated 95 by the Luftwaffe being tested at 95.5 in a
British lab then being rounded up to 96. The 96 then is called 100
because someone though that is close to 100 used by allied fuel.
Alternatively because someone did the testing and noted the
difference was close enough to be called equivalent.
Likewise the rich stoichiometric rating of 125 is rounded up to 130.
Ah yes, the claimed round up.
Between the increase from 92/110 to 95.5/125 British analysis appears
to may have noted an intermediate rating increase of 95/118 or so. It
is not certain whether this is deliberate or just substandard C3.
This corresponds with the stories of the Germans tinkering with C3 at
least three times. Any German engine tuned to run on 100/130 would be
in trouble when running C3. Meanwhile the allies are using more
115/145 and 100/150 than the Germans 95/125 C3.
You see here we have the desire to make the German aircraft engineers
into wonder people, so the German chemical engineers are downgraded
and the allied ones upgraded.
Meantime the allies standardised on 100/130 fuel in 1940/41 for their
combat aircraft, and the allied bombers stayed with that for the duration
of the war in Europe at least.
In 1944 the allies began testing 100/150 grade fuel, with the 8th air force
fighters going over to the new grade from July 1944 onwards, the final
group changing over in late September.
If you checked allied 100/130 or 115/145 or 100/150 fuel you no doubt
would find them generally of higher perfomance numbers then their
designation and I suggests though you would find them of more
consistent quality: allied refineries weren't disrupted by bombing.
Ah I see, now we will have the assumption the allied fuels were
above performance numbers but the Germans were below. The
story needs this sort of assumption.
B4 or "Blue" Fuel tested at between 87 and 91 lean but only about
81 rich. In other words it wasn't very fruitfull overboosting the
engine and controlling the resulting detonations by running the mixture
rich.
Rich lower than lean?
Interesting chemistry.
This explains the early German perfection of MW50 (Methanol
Water 50%) injection. P-47 pilots were frightened of activating their
ethanol/water systems: the less effective ethanol mixture froze and
blew up their supercharger over enemy territory.
Note by the way the Germans perfected it and the US installation
was wrong, at least this is the preferred story.
B4 was a fairly straightforward derivative of the German Hydrogenation
plants where a coal/oil slurry was pressurised with hydrogen at the
incredible pressure of 700 atmospheres. The aromatic and other
components to achieve the C3 rich mixture response had to be derived
from further refining and synthesis at considerable expense.
So now we head off into the story of fuels, taken from the various
web sites.
British 100 octane fuel was in fact quite different from american 100
fuel. The American fuel achieved its 100 lean rating by alkylation
(boradly increasing iso-actane or similar components). The British
fuels included aromatic compounds obtained from Venzuela, the Bahamas
and Brunei that gave a strong rich mixture response. It was these
components that the Germans had to learn to synthesise; not easy given
the amount of resources and trained personel dedicated simply to
develop coal to fuel synthesis. The specification is called BAM-100
"British Air Ministry"-100
And, of course, the allies pooled their fuels from 1942 onwards. So
the differences in formulations was not that relevant.
As for the Germans,
B-3, "It contained normally 10 to 15 percent volume aromatics,
45 percent volume naphthenes, and the remainder paraffins. "
C-3. "The C-3 grade was a mixture of 10 to 15 percent volume of
synthetic isoparaffins (alkylates and isooctanes) and 85 percent
of an aromatized base stock produced by hydroforming types of
operation on coal and coal tar hydrogenation gasolines. "
So DB605ASCM, means the A engine, with the bigger supercharger,The DB605DC emergency rating was 2,000 HP atØ sea level.
96 octane and methanol injection.
This is on the higher rated C3 fuel of 96/125 as the engine was only in
service in 1944.
As noted in my various posts.
The Bf109s fitted with the bigger superchargers were also fitted
with redesigned cowlings, with larger but more aerodynamic
bulges. And the bulge on the left side was larger than that on
the right side, given the supercharger arrangement.
So the bigger superchargers resulted in what looks like a more
streamlined arrangement.
The bulges disappeared in the Me 109G-10, which was produced by WNF and
were significantly reduced on some or all series of the K.
The bulges certainly did not disappear with the G-10.
The fuselage bulges were greatly reduced.
Having trouble with things again, first they disappear then they reappear.
The fuselage bulges were redesigned, they were made much larger
in area but more aerodynamic, how much further they protruded out
from the fuselage lines is another matter.
The new bulges are much harder to spot in photographs.
(snip) of list of late war Bf109 modifications.
http://forum.axishistory.com/viewtopic.php?t=88361&postdays=0&postorder=asc&start=45
"Amazing that the 1942 Bf 109F-4 managed a top speed of 416 mph on a
1350 (1390?) hp DB601E engine, while the 1943 Spitfire IX (HF
version),
weighing about 380 kg more than the 109F, needed a Merlin 70 of 1710
hp
to reach 415 mph.")
Now for some reality checks.
Please spare me from 'reality' checks in Sinclairs wonderland in future
please.
In other words the fiction is preferred.
It's you fiction.
No, as has been pointed out by others.
Note the above engine ratings, how incorrect they are, plus the
error in the F-4 top speed.
Ø >> at 21,000 feeet.For start 380 kg is around 840 pounds or
pushing around a 20% increase on the empty weight of a Bf109F-4 and
10 to 15% of the maximum Bf109F-4 loaded weight.
The HF Mark IX used the Merlin 70 rated at 1,475 HP, top speed 416 mph
at 27,000 feet.
The F mark IX used a 1,565 HP Merlin 61 or 1,650 HP Merlin 63 for a
top
speed of 408 mph at 25,000 feet.
The LF mark IX used a 1,580 HP Merlin 66 for a top speed of 404 mph
Note that two stage Merlins develop significantly more power than the
single stage Merlins at altitude.
That was the point of the two stage Merlins, as has been pointed out
by many publications over the years.
We have the LF Mk IX running at 404mph at 21,000 feet.
This corresponds with an altitude of 6300m at which point the Me 109F-4
was doing the following speeds:
630-635kph 390-393mph @ 6000m/20000ft worst case (data probably
from F2 for climb/combat power.
660-670kph 409-415mph @ 6300m/21000ft best case (data form Me
109F-4 overboosted and using takeoff/emergency power)
So tell us, given the Germans are no overboosting the engine, which
is a rather big do not do sort of thing, can you tell us what the Spitfire
would be doing with similar over boosting?
Is this the new deal, the Spitfire engine must be useful after the flight
the Bf109 engine can be wrecked?
Simply put the above speeds overstate the BF109F maximums by
around 20 mph.
http://www.spitfireperformance.com/109f_spitvb.jpg
Oh yes, the Spitfire IX was larger and heavier than the Bf109F.
Have a look at the HF Mk.IX with the Merlin 70. At 23,000/7000m feet
its engine is producing 1470hp which is slightly more than the DB601E
at its peak which is at 2200m (7300feet) its even more than the 1300hp
or so the 601E is producing at 4800m /16000ft or the 1070hp at
6300m/21000. At 7000m/23000ft, which is Merlin 70s peak output of
1470hp the DB601E is only producing 1000hp.
http://www.beim-zeugmeister.de/zeugmeister/index.php?id=30&L=1.
Is supposed to be the DB601E performance versus altitude graph.
Note the rapid fall off with altitude.
Now if you want the Bf109 power to look bad the obvious thing to
do is compare it to the HF mark IX, which had the "highest"
supercharging and therefore the highest speed at altitude.
http://www.spitfireperformance.com/spit9v109g.html
Yes folks, it appears Eunometic has been checking out the URL's
referenced in this thread, plus the Fischer Tropsch one I mentioned
some time ago.
No comment about the performance graphs of the various Bf109Gs
charted on the Spitfire web site I notice. After all the Bf109G-1 and G-2
were the F series with an engine rated at around 10% more power
then the F series but had top speeds below 400 mph in the
performance graphs.
Those figures do not fit the wonder Bf109 claims.
check both the
speed and peak power of the Mk IX at these altitudes.
And you can compare them to the various G models shown as well.
The G series is supposed to perform better at altitude by the way.
I suspect that
Spitifres higher boost means more exhaust gas thrust. Dynamic ram air
pressure would alter the power a little; generally improving it but
sometimes retarding it for both engines.
Now we have the usual speculation, what assumptions can be
floated to try and help the cause. Pseudo jet propelled Spitfires
it seems.
It's much the same story with the two stage Merlin 66 and even the
single stage Merlin 45 which is also producing more power at these
altitudes.
Yes folks, we are going to head for the best altitude for the Spitfire
for some reason.
So tell us the rated power of the Merlin 45 between 20 and 25,000 feet.
The F mark IX empty weight was around 5,800 pounds, maximum
weight 7,500 pounds, maximum overload 9,500 pounds.
As can be seen from the above supercharging settings were more
important than HP ratings when it came to top speeds.
As you vaguely isuggest none of these numbers matter much as they are
seal level figures out of context since you do not reference the power
v height curves or even the full pressure altitude to put them in
context. This is a graphical or baysian argument not a binary one.
Two stage Merlins were powerfull relaive to the German opposition but
'only' at higher altitude; say 15000 feet.
The claim was not about engines, but about airframes,
"I came across the point that the
Me 109F may have been an extra-ordinarily efficient aircraft "
To do this, the HP rating of the Spitfire IX was used and the one
chosen was wrong. This was compared to the HP rating of the
Bf109, which again was apparently wrong. Not surprisingly the
Spitfire was given a more powerful engine and it appears the
Bf109 a lower rated engine than those actually used.
Indeed the wrong hp rating of the Me 109F was used as well as the wrong
hp rating of the spifire as was pointed out in the thread I gave
reference to.
So why repeat the errors and then make the efficiency claims if you
knew the figures were wrong.
All things being equal?. The Mk IX two stage engine is
simply superior at all altitudes with the gap windening as the altitude
incrases.
And amazingly rather than compare things to the LF version of the
Mark IX the comparison wis with the HF version, the one optimised
for high altitude.
And no attempt will be made to explain how the Germans threw
away something like 30 to 40 mph, or around 10% of the top
speed going from the F to the G model Bf109 despite an
engine rated at 10% more power.
This should be a big clue the Bf109F performance figures
desired by the fiction are not correct.
The rated powers were given at rated altitudes which is
higher for the Mk IX (whaever variant), however this benefits the
Spitfire in terms of a speed vs power figure of merit as both the two
stage and single stage Merlin 66 or 70 is superior in the altitudes
under consideration.
So it is not surprising the Spitfire is generally faster then.
Incidenly mass efficiency of an aircraft is itself is meritorious: one
advantage of the Me 109's thicker wings was that they could provide
higher coefficients of lift, thicker more efficient spars etc., lower
weight. The disadvantages were higher compressabillity effects. The
higher weight was compensated to a large degree by superior fuels and
the Merlin.
yes folks, no drag calculations are going to be presented.
And of course the thicker the wings the more drag at speed.
I used the rated power of the engines, not the sea level ones.argument, notØ binary.
Apparently we now have the wonderful claim this is now a Bayesian
Indeed it is baysian; we need the power and speed charts for various
boost limits, dymanic pressures etc.
Bayesian sounds wonderful doesn't it? Meaningless as well.
Oh yes, note by the way the original claim simply used HP per MPH
as the way to determine the "best", now, having been caught out about
that we have the mimic method.
Agree with those who point out it is not that simple.
Note by the way we are now avoiding the Bf109 airframe and heading
towards the engine fitted. Nor is the difference in weights being
mentioned.
Power curves for supercharges show a decline with increasing altitude
and discontinuities as gear changes momentarily provide a slight boost
followed by a generaly more agressive decline. Another decline starts
occuring at full pressure altitude, which is the altitude at which the
supercharger can no longer maintain the maximum pressure the engine can
opperate at. In the case of the Daimer Benz engine a two speed gear
driven supercharger is also used as in the Melins but a continiously
variable hydraulic final drive is used to regulate precise pressure to
the manfold. Most other engines throttled and blew of the excess
pressure which is generally less efficient.
So now we have the what different superchargers did paragraph.
I'm establishing how supercharger performance effects engine power
with altitude.
No, rather you are writing a lot of material, or copying it, that has
little to do with the claim but a lot to do with masking the problems
with the fiction.
If the Me 109F4 demonstrated 420mph at 16000ft (where GM-1 is not used)
it is remarkable because it did so in thick dense atmosphere. It is
also completely sensible and a correction to history.
Except this figure contradicts things like the reported Bf109F
performance figures. It also means the Bf109G, with more power,
before the big bulges, lost performance, that is the G-1 and G-2
were slower than the F, despite an official 10% increase in power.
Early 109G2 were restricted to 1.3 atm vs 1.43 atm for the late 109F-4
so had only 3% more power albeit in a heavier airframe.
Yes folks, the idea I presume is to claim the power available was
about the same, which should mean comparable top speeds, but
the performance graphs given on the Spitfire web site show top
speeds below 400 mph.
And note that some 1.3 ata G series tests date from mid 1944
as well.
In any case it seems in order to make the Germans look good with
the F model they have to look bad with the G model Bf109 with
performance going backwards, by quite a large margin.
It means by mid 1943 the standard Bf109 was around 15% slower
than the F-4 of 1941.
The so called 386 mph as speed for and early Me 109G-6 has been in
dispute for a long time it represents the lowest end of the aircrafts
performance by far. 400mph is a closer figure and it is being
maintained at higher altitudes, with heavier armour and armament.
You know the Spitfire performance web site has a number of Bf109G
performance graphs, you should see how many of the different
trials have the Bf109G top speeds in the 380 to 390 mph area.
The mark IX chart given above shows a selection.
The mark XIV comparison chart gives the result of fitting the G
series with a bigger supercharger, sort of like the difference
between the LF and HF versions of the mark IX.
The new supercharger puts the Bf109 top speed above 410 mph,
about 700 out of over 10,000 Bf109G-6 were fitted with the bigger
supercharger.
Simply put the 390mph top speed was right for the majority of the
Bf109Gs, unless they were fitted with the bigger supercharger
or MW injection.
The typical G-6 had a top speed around that of the F-4, 390 mph
the extra power effectively going into extra armament etc.
1943 the boost is released from 1.3 to 1.42atm.
So where are the performance graphs?
Oh yes, the evidence supporting the above claim gives the best
speed altitude at around 21,000 feet.
No deployed
Merlin Spitfire could do this whether single stage or two stage. No
Spifire V at all and the Spitfire IX only by using its two stage
supercharger to allow it to opperate in to less dense higher
atmosphere.
Note by the way the basic problem with the above text, we have the
praise of the engine. Then all of a sudden it is the Bf109 airframe,
not the engine. Not what a Spitfire could do if fitted with the same
engine, which would be a better comparison of airframe efficiency.
You are hopelessly dishonestly rhetorical.
Ah the truth hurts it seems.
No, in order to tell us how wonderful the Bf109F airframe was we are
told all about the engine fitted.
So presumably the claim will mutate to the type had a more efficient
engine, at least low down.
Not at all. The 30L DB601E was fine engine but running 92/110 C3 fuel
it could not compete with the 27L Merlin 45 running 100/130 at any
altitude
What I really like is the way the best of the Bf109F tests were clearly
run using the better fuels.
However in service the Germans are lumped with inferior fuels and
therefore inferior performance.
Yes folks, the Bf109F was a wonder aircraft, not in service you
understand, but in the test flights using the best fuels.
Also things like what boost the Merlin was cleared to comes into
play, later engines could be boosted more than the earlier ones.
It's easy to understand incidently the PN number of 100/130 means
that 30% more power can be produced in the variable compression test
engine used to establish octane ratings and Performance numbers.
By the way apparently 125 performance number is supposed to be
significantly worse when the fuel is German.
MW50 could add about 12%.
So 125 performance plus 12% is 137%.
The 110 performance number becomes 122.
The usual ratings for the Bf109F-3 and F-4 engines is 1,300 or
1,350 HP delivering a top speed of around 390 to 400 mph at around
21,000 feet. The F-4/Z had GM-1. The F-4 empty and maximum weights
really vary between references, 4,330 to 6,220 pounds (Nowarra), 5,270
to 6,900 pounds (Green), 4,300 to 6,050 (Smith and Kay, quoting the
F-3),
2,225 kg (4,900 pounds) to 2,980 kg (6,550 pounds) (Nowarra in a
different
book), 4,320 to 6,060 pounds (Smith, quoting the F-3) 2,086 kg (4,600
pounds) to 2,870 kg (6,300 pounds) (Radinger and Otto), the upper
weight
being called class H5, and there was a load class H4, at 3,123 kg or
6,900
pounds for an extended range.
The rating of the DB601E at 2700rpm and 1.42 atmosheres boost is 1470hp
presumably on C3 fuel. The engine seems to have entered service at
around 1350 ps and 1.3 atm. Note a German DIN ps is slightly different
to an Imperial horsepower. The engine seems to have entered service at
1.3 atm but was uprated to 1.42 atm apparently due to improved spark
plugs and possibly a reformulation of C3 fuel.
The USN rates the German C-3 grade as roughly comparable
to the US 100/130 Performance Number grade, the standard
allied fuel for most of the war.
The late war 1944 grade is about 95/125 not 100/130 as you so
incorrectly insist upon. Early war grade was 92/110.
The USN rates the German C-3 grade as roughly comparable
to the US 100/130 Performance Number grade, the standard
allied fuel for most of the war.
The USN report is on the Fischer Tropsch site.
As Daimler Benz was playing with 2.2/2.3 atm boost. Levels of 2.4
atmosheres boost demands increases or at least conistency in fuel
standards to truly match 96/130 is conceivable. That suggest a DB605
producing 2400hp.
Yes folks, once again the Germans never did it, but could have.
The RAF was using around 2 atmosphere boost, + 25 pounds in
later Spitfires. An Atmosphere is about 14.7 pounds per square
inch.
So now by the way we have the new rating of the Bf109F-4
engine, it has gone from 1,350 to 1,470 HP, that is effectively
the same as the Merlin 70 fitted to the Spitfire HF mark IX.
The DB601E had a 30L displacement. It was cleared for an increase of
boost from 1.3 to 1.42 atmospheres while RPM increased from 2500RPM to
2700RPM on 92/110 C3 fuel.
Sorry but I need to read the reports to confirm the PN of the German fuel.
So the German Engine is rated at 1,470 HP at about 7,000 feet and
the Merlin 45 with +16 pounds boost could to 1,470 HP at 9,250 feet.
At 14,000 feet the German engine is around 1,300 HP and the
Merlin 1,415 HP.
The DB605 managed the same power initialy
at lower boost pressures of 1.3atm but it did so on ordinary B4 fuel,
it maintained power to higher altitudes. At this time German C3 fuel
seems to have had a mean rating of only 92/110.
The ratings of the engine as were probably obtained by an altitude test
chamber are as follows:
At sea level 1350ps; power then increases till
at 2200m the output climbed to around 1450ps, at this point a near
linear decline in output occurs untill at 4800m the power dropped to
around 1330ps.
I presume this is a report on page 13 of the DB601E performance graphs.
At the 109F-4's maximum speed of 670km/h which corresponds to 415mph
the engine would be producing 1120ps.
As noted the 415 mph appears to be fiction.
Now look at the figures on
http://www.beim-zeugmeister.de/zeugmeister/index.php?id=30&L=1
The above are the ratings that would be obtained in an altitude
chamber: however due to the speed of the aircraft the intake scoop has
a dynamic pressure (staudruck) that alters the effective altitude and
that adds considerably to power except at small range of certain speeds
at certain altitudes where it reduces it,presumably by adding so much
pressure that the supercharger transitions are altered to inefficient
points.
Note the size of the claimed pressures.
So the wonder efficient Bf109 airframe, at 20% less weight than
the Spitfire, now has an engine with the same basic HP rating
but a different supercharger set up, and around the same top
speed, but at a significantly lower altitude.
1 It's easier to make an aircraft go fast at high altitude given the
same power.
The Mustang was doing it at 10,000 feet, you are also the one claiming
the German superchargers were more efficient lower down, less power
loss.
2 Comparison with spitfire should be at the same altitude with known
power curves.
And with different Spitfire versions, given the changes that occurred,
the mark V was the least efficient Spitfire when it came to HP to MPH
figures.
3 Dynamic pressure effects on shaft output should be either included or
ignored equaly.
Alternatively the test flight data can be used.
4 The fastest Spitfire V clearly was a much slower aircraft than the
slowest tested Me 109F by 15mph.
The F-4 had a 15 to 25 mph advantage over the Spitfire V, the F-2
had a comparable top speed.
http://www.spitfireperformance.com/109f_spitvb.jpg
5 The Spitfire V has a significantly more powerfull engine at its rated
altitude than the early DB601E engines running at 1.3atm and a still
greater power than when the DB601 runs at 1.42.
Go note the HP figures above and note the rated altitude of some
Merlin 45s was 11,000 feet for example.
What Merlin 45 is being used?
6 The Spitfire IX has a significantly more powerfull engine at higher
altitudes due to its two stage intercooled supercharger.
Than the mark V certainly.
7 Merlin 45 - 1,470 hp (1,100 kW) at 3,000 rpm at 9,250 ft (2,820 m);
used in Spitfire Mk.V
So you are using the standard Merlin 45.
8 Other sources credit the Merlin 45 engine 1,515 hp (1130 kW) at
11,000 feet (3353 metres).
Fun isn't it? Do not forget the Merlin 45M, the lower altitude version.
9 DB601E 1,450 ps (1430hp) at 2700 rpm at 2200m used in Me
109F-4 on C3 fuel at 1.42atm.
Note the HP figures on the charts claiming the high speeds.
The above fuel would have been 92/110 C3 not the later 95/125 C3 fuel.
Assuming the fuel claims are correct.
According to charts it is producing 1310ps/1290hp at 4800m.
And around 1,100 HP at 6,000 metres.
10 Merlin 61 - fitted with a new two-speed two-stage supercharger
providing 1,565 hp (1,170 kW) at 3,000 rpm at 12,250 ft (3,740 m), and
1,390 hp (1,035 kW) at 3,000 rpm 23,500 ft (7,170 m); high-altitude
version used in Spitfire Mk.VII, Mk.VIII, Mk.IX, and PR.Mk.XI.
The Merlin 70 was the high altitude version, the Merlin 61 was the
medium altitude version. It is credited with giving a top speed of
408 mph at 25,000 feet.
The F-4 top speed was around 390 mph at 22,000 feet.
It's impossible to escape that the Me 109F airframe delivers
considerably more speed with less power. Than either the Spitfire Mk V.
The "impossible to escape" is the increasing of the top speeds of the
F-4 to make the claims possible.
Really simple, the early G models are suddenly around 20 to 30
mph slower than the claimed F model speeds. The Germans
keep building the G models and make them even slower by
adding bulges.
This is how stupid the Germans have to be to make the Bf109F
the wonder aircraft.
The same can be said of the Me 109F-4 and the Mk IX though in this
case the speeds are more or less matched at 20,000ft.
Simply put the claim about the Spitfire IX is wrong.
The directly comparable Mk V with similar power ratings delivers at
most 374mph while the Me 109F delivers a best speed of 416 of at
1.42atm and a worst case of 390 at 1.3atm.
The Bf109F-4 best speed claim is really a joke. By the way there are
test results of Spitfire Vs doing over 380 mph, above the reported
top speeds.
Note by the way the Spitfire's are peaking at around 19,500 feet versus
the 22,000 feet of the Bf109F-4.
yes folks, they are doing it at a lower altitude. Silly isn't it?
Meantime I have finally found some figures from the Spitfire
fitted with a DB engine and compared to the Bf109G fitted
with the same engine, apparently for doing cooling trials.
So much for my memory, I confused the Spitfire II trials with
the above trials which were done with a Spitfire V, EN830,
built as a mark VC.
The Spitfire had the armament stripped, not sure about the
cannon shrouds.
At sea level the Spitfire did 300 mph versus the Bf109G 316 mph,
at 8,200 feet it was 338 to 352 mph, at 22,000 feet it was 379 mph
versus 385 mph. Interesting the way the top speeds keep
converging, the speeds above 22,000 mph would be interesting.
Not surprising the bigger airframe closes the speed gap as the
altitude increases.
The Spitfire was supposed to be climbing at 3,540 feet per minute
at 19,000 feet versus 2,520 by the Bf109G. Remembering the
Spitfire had no armament, so a lot less than normal weight.
The speed difference at 22,000 feet is within the margin of
error of the airframes and any incorrect cooling in the Spitfire.
What was that about how captured aircraft were so battered they
always underperformed, or is that only captured German aircraft?
So much for the much faster Bf109.
Yes folks, the BF109 is a very efficient airframe, just alter the
power outputs of its engine, its "rival's" engine, and then
spend lots of time telling us how good the engine is.
So 'folks' the tactic is to take the weight and performance of the
Heavy and later Spifire Mk IX and mention that it is 20% heavier than
the 109F, then that it has the same 'rated' power as the Me 109F
while ignoring the fact that the Mk IX has a two stage intercooled 60
series supercharger that maintains this engines power at altitude far
better then either the single stage of the Merlin 45 or 46 of Mk V
Spitfire or the Me 109's . DB601E. Yes folks and then its faster
while picking and conflating suitable data this from the the Mk V and
Mk IX.
Eunometic is admitting how the figures Eunometic reports are
being rigged, apart from the boosts to the F-2 and F-4 top speeds
to make it all possible.
Meantime I follow the comparisons being given and show they are wrong.
It also begs the question why did the G series go to the DB605
when it would be putting out less power than the engine it is
supposed to be replacing.
Unfortunatly all of the sources both the German and Other ones (Kay
must be fluent in German and takes his sources from the German ones)
are the old typical sources that suggest Me 109F performance lies
between 390 and 400mph.
Note by the way the same performance reports came from the allies
testing captured aircraft.
No they don't.
Yes they did.
The Reichlin test reports indicate at least 670km/h. Reichlin was the
Luftwaffes test center: they had no interest in exaggerating
performance of aircraft.
I like the "at least" bit, in a chart that has at least 2 of the performance
curves calculated. The idea all might be calculated is going to be
ignored.
Note the two performance test from Messerschmitt.
http://www.beim-zeugmeister.de/zeugmeister/index.php?id=28&L=1
By the way, note below I comment extensively on the different
top speeds being reported.
They are being repeated here.
On the left photocopy/photograph, in the top box under the heading
"Allgemeign" which is the german were for "all in common" or
"general". The left box, 3rd line down, list the maximum speed of
the Me 109F-4 as "Vmax at 635km/h at 6000m H" The line above
shows a Nominal power of 1185ps at Vmax. Which is 394mph.
Congratulations on noting the top speed.
Now look at the corresponding box in the right form is for the engine
producing the higher takeoff and emergency power as opposed to climb
and combat power.
The speed is now listed as "Vmax at 670km/h at 6300m" the power at
Vmax is listed as nominal
The engine output is put at 1,290 at 6.3 km, this is the best part of 200
HP more than the DB601E is supposed to be able to produce at that
altitude at 2,700 RPM and 1.42 ata of boost. You have to drop to around
5,000 metres to produce the relevant HP rating.
Of course using GM-1 would close the gap.
See the trouble?
Oh yes, the allies captured a number of Bf109F-4's including come
that were intact.
And seemingly they had to remove and replace damaged engines from
earlier aricraft in what were beaten up airframes.
No, the allies captured a number of F-4s, some of which were intact.
The USSR apparently handed 2 intact ones to the US for example,
the South Africans shipped one home.
(snip) of horsepower definitions.
Ø > issues became resolved.In fact the DB601E of the 109F could produce 1475hp on C3 fuel when its
permisable boost was raised from 1.3 to 1.42 atm when the appropriate
I retract the above figure of 1475hp and replace it with 1450ps (about
1430hp) incidently.
Fine, the trouble is the original figure was much lower.
So why, when comparing the Bf109 to the Spitfire was the lower rated
HP used for the Bf109 and a much higher than actually fitted HP rating
used for the Spitfire?
It seems the sea level static rated emergency and takeoff power with
1.42atm was used this is 1350 but rises to 1450ps/1430hp at 2200m and
drops to 1330ps/1300hp at what must be full pressre altitude when the
final gear kicks in at 4800m and a rapid decline in power starts.
So why not answer the question, rather than repeating the data?
Things like the optional bomb racks and underwing armament seem to
be complicating the reported weights.
The 416 mph speed, if correct, would appear to be a GM-1 run.
I refer you to this gentlemens pages. He has reproduced the original
curves and reports:
http://www.beim-zeugmeister.de/zeugmeister/index.php?id=13&L=1
The author notes the Bf109G and FW190 with the BMW801D are
calculations. And the Bf109G calculation assumes a top speed of
740 km/hr or 460 mph.
So this lays out the chance the F-4 are calculations rather than
test runs, as a way of comparing the proposed changes.
no reply here.
In October 1941 Rechlin ran trials on a number of Bf109F-4s
and Fw190A-1s. Apart from showing the F-4 was generally
better it also noted there was an exceptional F-4, along with
an exceptional A-1.
An exceptional Mosquito managed 437 mph under test, when
the production versions were rated around 420 mph.
No reply here.
The claim is by the way
"If the Me 109F4 demonstrated 420mph at 16000ft"
If you look at the graph in the reference given the peak performance
claimed is 670 km/hr at around 6,400 metres or 420 mph at 21,000 feet.
Several things argue against this being an GM-1 run.
1 The power curves do not include the notion "Mit GM-1", not a thorough
argument but I've seen this notation used in Reiclin reports.
2 GM-1 can not be engaged below full pressure altitude. This appears
to be to low for that.
And at 21,000 feet?
No reply here.
3 The test weights indicate that the aircraft was not carrying nitrous
oxide
4 The aircraft is no described as being an Me 109F-4/Z with the Z
indicating GM-1.
5 Without GM-1 the 109F4 could maintain at about 416mph at 6250m
(21,000 feet) with GM-1 the 109F4/Z seems to have been able to do the
same at 8000m.
The above assumes the graph is correct and not an entire set of test
calculations based on different configurations.
Meantime
Page 9 gives Luftwaffe figures of 670 km/hr at 6,200 metres for the
F-4 and 700 km/hr at 7,000 metres for the G-1. This is interesting
given the G-10 is normally credited with being the fastest of the
G series, but it would be around 15 km/hr slower than the G-1,
which would, if the figures are correct, have a top speed in the
order of 440 mph or comparable to the K series top speed. By the
way the Fw190A-3 is credited with 700 km/hr at around 5,900 metres
"projektwerte".
No reply here.
Page 10 notes Messerschmitt performance figures were
around 660 km/hr at 6,200 metres as of November 1941, using
1,180 PS.
Page 11 notes Messerschmitt performance figures were
around 635 km/hr at 6,200 metres as of July 1942 using 1,185 PS
Page 12 has two figures, 635 km/hr at 6,000 metres at 1,195 PS and
the second 670 km/hr at 6,300 metres using 1,290 PS. Both are
Messerschmitt documents and both are dated February 1943.
The lower figure is "arguably calculated", which raises the
question why not the upper figure? After all aircraft
manufacturers are more likely to over claim than under claim.
No reply here.
The climb rates do not change despite the various top speeddifferences.Ø
If sonder noteleistung was only available for 3/5 minutes it probably
wasn't used.
Presumably for climb, yet 3 to 5 minutes is comparable to the
time to climb to 15,000 feet.
Another figure from the Luftwaffe for the F-4, with the engineinches of mercury at 32 degrees F.Ø
able to develop 1,350 HP at 2,700 RPM is said to be 606 km/hr
which the book in question equates to 410 mph, which would
be around 660 km/hr., implying a typo in the metric figure.
Page 13 suggests adding "impact pressure" to the engine
performance graphs being displayed in order to obtain the
high speeds being claimed. The site wants to add 700 to 800
kg per square centimetre., where 1 atmosphere is 1.03323 kg per
square centimetre or 14.696 pounds per square inch, or 29.9213
Staudruck translates to stagnation pressure but the concept in english
is dynamic pressure.
Does not answer the problem, look at the pressures.
The performance chart gives a range of power at 6 km, betweensettings do not deliver the most power at 21,000Ø feet.
1,050 and 1,200 PS. The interesting thing is the highest boost
speed, all at about the same altitude it seems.Ø
Overall the documents presented are quite consistent about
climb rates, but vary between 635 and 670 km/hr as the top
6000 vs 6300; that's a 1000ft and probably 3% less pressure.
So about the same altitude.
Which rather leaves a problem, that could be resolved by thefar as the standard F-4 in LuftwaffeØ use.
boosting, or by some real build quality issues.
It also means if the F-4 and G-1 were that good the G-6 series
was a significant step backwards, with a top speed below
390 mph.
So overall the claims about 670 km/hr do not fit, at least as
It fits if improvements in engine tuning, fuels and spark plugs allow
an latter in servive release of the higher boost pressure: the Daimler
Benz figures of 1350ps (sea level) are well noted while the speeds
changes are not generally known. The Germans are not going to
directly provide published data of Me 109F-4 performance.
Ah now it seems we have a secret performance aircraft.
So we should take all German figures with a significant reserve
right? They might be telling stories?
Take a look at the Db engine performance versus the quoted HP
needed to do the claimed high top speeds.
(snip) of figures showing the edge or equivalence the early Spitfires
had to the early Bf109s.
When the Mk V entered service it had an considerably more powerfull
single stage Merlin. Its contemporary, the Me 109F, also had an
improved engine however while the Mk V or IX for that matter introduced
no major aerodynamic improvements the Me 109F dramatically cleaned up
the nose and greatly improved the radiators and changed the outer wing
planform and profile.
You see the point here is to compare the mark V with the Bf109F.
Becuase they are a closer match.
No, because the Spitfire V is the worst of the models when it
comes to the HP per MPH yardstick chosen.
Now it is generally agreed the Bf109F was the best, aerodynamically,
of the Bf109 series, it cleaned up the Bf109 airframe and managed a
more powerful engine on about the same or better loaded weight
than the E series.
Meantime the mark V suffered the weight gains, nearly 20% more
than the mark I and as a result had the same top speed as the mark II
despite the more powerful engine ratings.
The Merlin 60 series Spitfires managed a better than 10% increase
in top speed over the mark Vs on something around a 5% increase
in rated engine power. The best increase is the HF mark IX, around
a 13% increase in top speed on no increase in engine rating.
Of course supercharging arrangements matter.
So if you want to make the Bf109 look good, pick its best, in terms
of HP per mph, the F-4, and compare it to the Spitfire V, which was
the worst of the Spitfire versions for such a figure. Simple really.
The simple reality is not matter how you twist and turn the slowest Me
109F-4 goes significantly faster with less power than any Mk V spitfire
and it does it on less power.
It is really simple in the HP per MPH rulings,
The Spitfire I is better than the Bf109E.
The Spitfire II is about the same as the Bf109F-2
The Spitfire V is worse than the Bf109F-4
The Spitfire IX is better than the Bf109G.
Hence the way the comparison Spitfire changes depending on
what is required.
Spitfire power efficiency was in general unremarkable; it did have a
good light engine with good quality fuel.
Except as noted the mark I was faster than the Bf109E, with a
lower rated engine, the mark II could match the earlier Bf109F-1
and -2 using an similarly rated engine.
And the mark VII, VIII, IX, XVI series could also match the
Bf109F and certainly the G models, using similarly rated engines.
After all look at the weight differences.
Note David Ledicners comment:
http://yarchive.net/air/spitfire.html
Basically he thinks things, but has not done the calculations, and the
comparison is with the Mustang.
He's an expert in computational flow dynamics and has performed a
landmark comparison of the P51C and D with the Spitfire IX, Fw 190A and
D using computational flow dynamics. Of coruse after attempting to
discredit the man without you confirm his statements in your tangent
about the P-51 below.
I do not discredit the man, I note he has not done the calculations
and the British knew the Mustang was a more efficient airframe
than the Spitfire.
As is easily obvious by the comparison of the top speeds between
the Merlin 60 Spitfires and the Merlin Mustangs.
Meantime the RAF found as follows, the Mustang I (P-51A) drag
figure was 50 pounds per 100 feet per second, whereas the average
Spitfire figure was 65.5 pounds per 100 feet per second, as of mid
1942.
Using the V-1710 F3R, peak output 1,150 HP at 3,000 RPM at 12,000
feet, the Mustang I top speed was 370 mph at 15,000 feet.
Fitted with the V-1710 F21R, with reduced supercharger gearing the
top speed went to 377.5 mph at 4,000 feet.
The Mustang II, with the F20R engine fitted managed 409 mph at
10,000 feet.
The US rating for the Mustang engine was 1,200 HP for take off
and 1,330 HP military power. The empty weight of the early
Mustangs was around the maximum loaded weight of the Bf109F-4.
The P-51 was a very efficient airframe.
I don't deny it.
However the claim is the Bf109 was better, which is quite wrong.
Since the P-51B, C and D were fitted with basically the same engines
as the Merlin 60 series Spitfires you can see this from the way the
P-51 had around a 30 mph increase in top speed.
A similar comparison can be made between the Spitfire I and the
Hurricane I.
Meantime the comparison of airframes between the Bf109 and
Spitfire requires both be fitted with the same engine. Assuming
there are not problems in doing so.
Many of the Me 109F's advantages in lightness were surrendered when the
changeover to the Me 109G in order to allow heavier armament and armour
to be carried while often using lower grade B4 fuel that must have been
neccesary to attack the bomber streams. Very few two stage
superchargers were used by the Germans in part because of manufacturing
issues and in part becuase they were able to improve single stage
superchargers fluid dymanics.
The G-6 gained around 10% in weight terms over the F-4.
The K-4 was around 15% heavier than the F-4.
The big problem for the G series was the bulges, to carry heavier
armament and the landing gear needed to support the weight.
Simply put it seems Messerschmitt designed the lightest undercarriage
it could when the Bf109 was first built and had to pay for it later when
the weight increases required strengthening.
They designed an undercarriage for a 1935 era aircraft that ran on 20L
700hp engines. The 109 was a predecesor not only the Spitfire but the
Hurricane as well.
I presume this is supposed to read the Bf109 first flew before the
Spitfire and Hurricane. May 1935 versus November 1935 for the
Hurricane and March 1936 for the Spitfire.
Strangely the Spitfire undercarriage was not considered as bad
as the Bf109, despite the increases in weight. The Bf109 was
criticised from quite early in its history for having a weak
undercarriage.
Apparently the fact it was a few months earlier is an excuse for
bad landing gear, despite the fact the DB engines were being
fitted into the prototypes before the BF109B entered service
and years before the Bf109E did so. The B model came in at
about 3,500 pounds empty, the E at around 4,700 pounds.
One of the first fixes ordered was a strengthening of the undercarriage
and this is before the B model.
So the G-6 was slower than the late F and early G series. The clean up
in the K model and a more powerful engine created the fastest of the
Bf109s, around 10 to 15 mph faster than the P-51 using around 20%
more power.
Had the Me 109F been directed only at other fighters developed two
stage non intercooled versions of the smaller DB601 engine should have
been adaquete.
Yet again something the Germans never did is given as the answer.
They developed the DB605L and engine only 15kg heavier than the DB605
it maintained 1300hp to 9700m. The reality is however that without
increased supplies not only of cs fuel but the uprated 96/125
increasing swept volume was the only way to go. Provide 96/125 or
100/130 high octane fuel to a developed DB601E its power increases by
20%.
By the way note we are back in best engine territory, not best airframe.
Geoffrey Sinclair
Remove the nb for email.
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