Use of 150 octane fuel in the Merlin (Xylidine additive etc etc)

In article ,
(Hildegrin) writes:
Cub Driver wrote in message . ..
British based Spitfire IX squadrons had converted to 150 octane
(actually 100/150 octane, for lean/rich rating) by, or during, May 44.

Is this the same as 100 octane, then? As used for example in the
Curtiss P-40?


The common 100 octane fuel had an octane rating of 100/130, which
means 100 in lean mixture, 130 in rich mixture. 150 octane was
actually 100/150. I suppose that means no difference in lean mixture,
but in rich it had a tremendous effect. The Merlin went from 67" to
82", for example (although the USAAF rated them more conservatively,
at 72" iirc)

100/150 wasn't in use until the spring of 1944, although it was being
tested in 1943.

The Lean Mixture/Rich Mixture rating system didn't get adopted until
late 1942 or early 1943. (For those who don't know, the first number
is the Lean Mixture rating, the second is the Rich Mixture.
Before then, ratings were rather arbitrary, and true antiknock
performance depended on various characteristics of the individual
blend. Since Gasoline isn't a specific chemical, but a blend of
various hydrocarbons, performacne at one particular test point didn't
necessarily mean the same performance across the full range of
conditions. The Lean/Rich rating system, standardized testing using
calibrated sensors to detect knock, and the definition of
characteristics that were seen to be important (Antiknock, Vapor
Pressure, viscosity, Specific Gravity, & a whole slew of other stuff)
was an important bit of standardization by the U.S. and U.K.

Hildegren, have you checked out the N.A.C.A. Technical Reports Server?
(It's also mirrored at Cranwell) Among the thousands of reports is a
whole series on Aviation Fuel development, and the development of
testing methods.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

In article , WaltBJ
writes
Slightly off track - the Germans did not seem to place the same level
of importance on recce that the Brits and USAF did. Me109s could (some
did) carry a camera in the aft fuselage like the recce P51s (F6?). A
lightened waxed Me109F or G would have a very good chance of
completing a recce pass on an in-and-out basis flown at max speed on a
curving descent or in-and-out at naught feet (prop tips above the wave
tips). It appears to me that the 86R was declared a 'clay pigeon' when
the LW found out Spits and Mosquitoes, appropriately modifed, could
get up that high. Why the LW didn't use 'hot-rodded' photofighters is
beyond me. Maybe they swallowed the 'XX' turned spies' reports as
gospel.
Walt BJ

Yes, the success of agents like 'Garbo' in feeding duff stuff to the
German High Command was remarkable.

Without wanting to go wildly off-topic, there was a programme on UK TV a
few nights ago ('Spitfire Ace') that had some very useful stuff on the
mentality of the RAF versus the that of Luftwaffe in 1940. The RAF
(through the vision and efforts of Dowding) had created a parless air
defence system, while the Luftwaffe had concentrated overmuch on the
lionisation of its individual pilots. I think that by 1944 the Allies
had developed a war machine that was thorough enough to filter out most
flakey thinking and to concentrate on the real issues. If the Luftwaffe
in 1944 was still relying on the whims of 'gifted individuals' (Hitler,
Goering), who would have prided their own (uncriticised) judgement then
a lot of bad ideas would have good through and a lot of good ideas would
have been turned away.

Cheers,

Dave

--
Dave Eadsforth

In article , Keith Willshaw
writes

"WaltBJ" wrote in message
. com...
Slightly off track - the Germans did not seem to place the same level
of importance on recce that the Brits and USAF did. Me109s could (some
did) carry a camera in the aft fuselage like the recce P51s (F6?). A
lightened waxed Me109F or G would have a very good chance of
completing a recce pass on an in-and-out basis flown at max speed on a
curving descent or in-and-out at naught feet (prop tips above the wave
tips).


The Me-109G-8 recce variant had a camera in the aft fuselage and did
conduct some photo recon missions over the channel area in 1944.

Keith



Hi Keith,

Do you happen to know whether these were conducted at high level, low
level, or the max speed altitude for the 109G-8?

Cheers,

Dave

--
Dave Eadsforth

On 30 Jan 2004 14:50:00 -0800,
(Hildegrin) wrote:

The common 100 octane fuel had an octane rating of 100/130,

Okay, thanks.

I reckon that piling 100/150 on top of 100/130 is what led to the
regular use of the two octanes in naming the fueld.

In 1942 in Southeast Asia, 100 (presumably 100/130) was called just
that, or "high octane" to distinguish it from the 80 octane used by
the RAF.


all the best -- Dan Ford
email:

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com

Dave Eadsforth wrote:

: Yes, the success of agents like 'Garbo' in feeding duff stuff to the
: German High Command was remarkable.

The familiar problem, as far as I know:
Too many different intelligence services, every
one a part of the personal empire of a different
Nazi leader, and unwilling or unable to cooperate.
And of course the 'Abwehr' leaked like a sieve.

The Germans did produce recce versions of fighters,
usually with fewer guns and more fuel; in addition
to cameras of course. But I suspect the Bf 109 was
just less adaptable to the task than the Spitfire.
It was even smaller.

The Spitfire had inherited a D-shaped leading edge
structure from its direct ancestor, the Supermarine
227, which used this as a condensor for its
steam-cooled Goshawk engine. This made a great fuel
tank for the long-range reconnaissance versions.
With better fuel and more powerful engines, these
models could also operate at higher weights and
reach higher altitudes than Bf 109s.

On the other hand Ju 88s were less suitable for
reconnaissance than Mosquitoes, because they were
bigger and slower. Still, the Germans did develop
a high-performance recce aircraft in the Ar 234A.

Emmanuel Gustin

Others have already hit on what effect higher octane ratings had. Peter
Stickney will probably have one of his great replies coming along soon
too. But here is a quick rundown on what 104/150 octane should provide
for a Merlin 266.

The US had an empirical formula for calculating MAP limits at different
PN. It is a little conservative, but gives a good ballpark figure.

((old MAP -7) * new PN/old PN) +7 = new MAP

So, 66.6 in Hg on 100/130 octane would give:

((66.6 - 7) * 150/130) +7
59.6 * 1.154 + 7 = 75.76 in Hg

The RAF actually used +25 psi, about 80.9 inches.

We know the Merlin 266 was rated at 66.6 in Hg, 1705 hp @ 5750 ft in low
blower. That is enough information to approximate how much power the
engine provides at any altitude.

We also know static pressure at 5750 ft is approx 24.20 in Hg. So,
dividing 66.6 by 24.20 gives us approx 2.75 for the pressure ratio that
the Merlin 266 provides in low blower.

Multiplying static pressure by the pressure ratio gives the manifold
pressure available at any altitude. 80.9 in Hg would be attainable up
to about 500 ft unrammed, and approx 82.4 in Hg at SL.

Since we know it produces 1705 hp @ 66.6 in Hg we can figure how much
it makes at 80.9 in Hg. 1705 * 80/66.6 gives about 2071 hp. Then you
have to take the difference in temp into account. Sqrt of absolute temp
at 5750 ft / absolute temp at 500 ft times 2071 hp.

(sqrt (276.86 / 287.36)) * 2071 = 2032 hp @ 500 ft.

(I'm using the 1976 standard atmosphere for all calculations, older
atmosphere models might provide slightly different figures)

This should be accurate +- about 1%. You can do the same thing for just
about any engine, provided you have an accurate base altitude, power and
MAP rating to start with. I cheated and created an Excel spreadsheet
that does all the work for me.

You need to make sure and use static ratings, a lot of RAF ratings are
with 350 or 400 mph RAM which will screw things up. RAM will cause a
higher rated altitude from the ram pressure, but lower power due to
compression heating.

Greg Shaw

(Peter Stickney) wrote in message ...
In article ,
Dave Eadsforth writes:


No, As with anythig else in Aviation (Or any other Engineering), it's
a balancing act. You can only get so much of a compression ratio out
of a Supercharger, for any given drive speed. In order to get more
boost, you've got to start with thicker air, so the Critical Altitude
actually decreases. When you're chasing V-1s, though, or fighting
against Me 109s, or Fw 190s, that's not a bad thing. The Daimler Benz
engines in the 109, by virtue of their variable-speed blowers, which
didn't require as much power to run at low altitudes, gave a big
advantage down low. The BMW 801 on an Fw 190 had a geared blower, but
the critical altitude for the low gear was very low, down near Sea
Level.
In order to improve altitude performance, you've got to increase the
compression ratio of the induction system, or add an axidizer to the
fuel-air mix to help it burn. This can be done by adding supercharger
stages (Basically one supercharger feeding another, like, say, a
Merlin 60 series engine, or the turbosupercharger/engine driven blower
setups on the P-47 and P-38, or piping something like Nitrous Oxide
into the induction system, as the Germans did.

The drawback is that
it takes more of hte engine's power, in the gear-driven examples, to
compress the air that much more. That means that at lower altitudes,
you're at a disadvantage. Or, you've got got to haul around a bunch
of tanks, regulators, pipes, valves, & all that for teh Nitrous
system. You've only got a limited quatity of Nitrous aboard, and you
can pretty much guarantee that it'll run out right when you need it.
Or, worse yet, the storage bottles could get damaged. Leaking
Oxidizers is a Bad Thing, especially when somebody's shooting at you.

More later, with real numbers attached.


Nitrous oxide was more a technique the Germans were forced into to
help overcome a German disadvantage in high octane or high test
aviation fuels rather than a paucity in thingking.

The Germans did have techniques for manufacturing octane and even
higher knock hydrocarbons their technology was however more cumberson
than the US technology and this limited their production rate. Why
this was I don't know. It may have had something to do with the fact
that they had access to only snythetic oils from fischer tropsch and
hydrogenation plants or their own small crude oil industry or
Romania's all of which are regarded as poor quality crudes.
(California crude was rather highly regarded). It may have just been
that they were unaware of the US techniques.

Nitprous oxide also was used only at higher altitudes: water methanol
injection was used at low altitude.

The Ta 152H has a watern methanol and nitorous oxide system. The
clipped wing Ta 152C has only water methanol for its BB603LA

The Jumo 213E had a two stage 3 speed supercharger WITH an induction
cooler. It still had water methanol and nitorus oxide (nickamed HA HA
system because Nitorus oxide was laughting gas)

Ta 152H Engine: Junkers Jumo 213E-1 twelve-cylinder liquid-cooled
engine rated at 1750 hp for takeoff (2050 hp with MW 50 boost) and
1320 hp at 32,800 feet (1740 feet with GM 1 boost). Maximum speed: 332
mph at sea level (350 mph with MW 50 boost), 465 mph at 29,530 feet
with MW 50 boost, 472 mph at 41,010 feet with GM 1 boost. Service
ceiling was 48,550 feet with GM 1 boost. Initial climb rate was 3445
feet/minute with MW 50 boost. Weights were 8642 pounds empty, 10,472
pounds normal loaded, 11,502 pounds maximum. Wingspan 47 feet 41/2
inches, length 35 feet 1 2/3 inches, height 11 feet 0 1/4 inches, wing
area 250.8 square feet.

The Ta 152C-1 was powered by a Daimler-Benz DB 603LA twelve-cylinder
liquid cooled engine rated at 2100 hp (2300 hp with MW 50) for takeoff
and 1750 hp at 29,530 feet (1900 hp at 27,560 feet with MW 50). Armed
with one engine-mounted 30-mm MK 108 cannon with 90 rounds, two
fuselage-mounted 20-mm MG 151 cannon with 250 rpg, and two
wing-mounted 20-mm MG252 cannon with 175 rpg. Maximum speed was 227
mph at sea level (356 mph with MW 50), 436 mph at 37,730 feet (460 mph
at 32,810 feet with MW 50). Initial climb rate was 3050 feet per
minute and service ceiling was 40,350 feet. Weights were 8849 lbs
empty, 10,658 lbs normal loaded, and 11,733 pounds maximum. Wingspan
was 36 feet 1 inch, length was 35 feet 6 1/2 inches, height was 11
feet 1 inch, and wing area was 290.89 square feet.

Dave Eadsforth wrote in message ...
In article , WaltBJ
writes
Slightly off track - the Germans did not seem to place the same level
of importance on recce that the Brits and USAF did. Me109s could (some
did) carry a camera in the aft fuselage like the recce P51s (F6?). A
lightened waxed Me109F or G would have a very good chance of
completing a recce pass on an in-and-out basis flown at max speed on a
curving descent or in-and-out at naught feet (prop tips above the wave
tips). It appears to me that the 86R was declared a 'clay pigeon' when
the LW found out Spits and Mosquitoes, appropriately modifed, could
get up that high. Why the LW didn't use 'hot-rodded' photofighters is
beyond me. Maybe they swallowed the 'XX' turned spies' reports as
gospel.
Walt BJ

Yes, the success of agents like 'Garbo' in feeding duff stuff to the
German High Command was remarkable.

Without wanting to go wildly off-topic, there was a programme on UK TV a
few nights ago ('Spitfire Ace') that had some very useful stuff on the
mentality of the RAF versus the that of Luftwaffe in 1940. The RAF
(through the vision and efforts of Dowding) had created a parless air
defence system, while the Luftwaffe had concentrated overmuch on the
lionisation of its individual pilots.

Honestly this sounds like Brits patting themselves on the back while
not looking at the strategic and tactical issues the Germans faced.
(sadly this is a sort of anasthetic as the UK goes down a sewer)


I think that by 1944 the Allies
had developed a war machine that was thorough enough to filter out most
flakey thinking and to concentrate on the real issues. If the Luftwaffe
in 1944 was still relying on the whims of 'gifted individuals' (Hitler,
Goering), who would have prided their own (uncriticised) judgement then
a lot of bad ideas would have good through and a lot of good ideas would
have been turned away.


German thinking was predicated on the need to fight a short and sharp
war as a nation sourunded by hostile countries. Avoiding a war of
attrition was essential and avoiding a war on German territory was
also essential. The nation was physically to small and to devoid of
materials to handle a war in any other way and not loose thus
substantial offensive capability was emphasised but it was all up
front: resources were not devoted to reinforcements. This was the
thinking even before the Nazis came to power.

Much of the German work on Microwaves and Proximity fuses (which
inspired British research) was suspended because the anything that
could not be ready in 2 years would be a waste. It seems that at
this point that many of the German might have beens got caned.
Examination of this period is perhaps where it might be said that
Germany's technical may be said to lie. It migh also just lay in the
fact that Germany lacked the resources to develop them. The Tiazard
commision handed the proximity fuse and magnetron on a platter for the
USA to develop. The Germans just culled.

The excelent Freya and Wurzburg Radars were not integrated into a
defensive system because the bomber naviagation aids were considered
more important.





Cheers,

Dave

In article , The
Enlightenment writes
(Peter Stickney) wrote in message news:dbocvb-
...
In article ,
Dave Eadsforth writes:

SNIP of repeated material

Nitrous oxide was more a technique the Germans were forced into to
help overcome a German disadvantage in high octane or high test
aviation fuels rather than a paucity in thingking.

The Germans did have techniques for manufacturing octane and even
higher knock hydrocarbons their technology was however more cumberson
than the US technology and this limited their production rate. Why
this was I don't know. It may have had something to do with the fact
that they had access to only snythetic oils from fischer tropsch and
hydrogenation plants or their own small crude oil industry or
Romania's all of which are regarded as poor quality crudes.
(California crude was rather highly regarded). It may have just been
that they were unaware of the US techniques.

Nitprous oxide also was used only at higher altitudes: water methanol
injection was used at low altitude.

The Ta 152H has a watern methanol and nitorous oxide system. The
clipped wing Ta 152C has only water methanol for its BB603LA

The Jumo 213E had a two stage 3 speed supercharger WITH an induction
cooler. It still had water methanol and nitorus oxide (nickamed HA HA
system because Nitorus oxide was laughting gas)

Ta 152H Engine: Junkers Jumo 213E-1 twelve-cylinder liquid-cooled
engine rated at 1750 hp for takeoff (2050 hp with MW 50 boost) and
1320 hp at 32,800 feet (1740 feet with GM 1 boost). Maximum speed: 332
mph at sea level (350 mph with MW 50 boost), 465 mph at 29,530 feet
with MW 50 boost, 472 mph at 41,010 feet with GM 1 boost. Service
ceiling was 48,550 feet with GM 1 boost. Initial climb rate was 3445
feet/minute with MW 50 boost. Weights were 8642 pounds empty, 10,472
pounds normal loaded, 11,502 pounds maximum. Wingspan 47 feet 41/2
inches, length 35 feet 1 2/3 inches, height 11 feet 0 1/4 inches, wing
area 250.8 square feet.

The Ta 152C-1 was powered by a Daimler-Benz DB 603LA twelve-cylinder
liquid cooled engine rated at 2100 hp (2300 hp with MW 50) for takeoff
and 1750 hp at 29,530 feet (1900 hp at 27,560 feet with MW 50). Armed
with one engine-mounted 30-mm MK 108 cannon with 90 rounds, two
fuselage-mounted 20-mm MG 151 cannon with 250 rpg, and two
wing-mounted 20-mm MG252 cannon with 175 rpg. Maximum speed was 227
mph at sea level (356 mph with MW 50), 436 mph at 37,730 feet (460 mph
at 32,810 feet with MW 50). Initial climb rate was 3050 feet per
minute and service ceiling was 40,350 feet. Weights were 8849 lbs
empty, 10,658 lbs normal loaded, and 11,733 pounds maximum. Wingspan
was 36 feet 1 inch, length was 35 feet 6 1/2 inches, height was 11
feet 1 inch, and wing area was 290.89 square feet.

Thanks for this very useful summary - very much appreciated.

Cheers,

Dave

--
Dave Eadsforth

In article , The
Enlightenment writes
Dave Eadsforth wrote in message
news:s9BISHBVA3GAFw82
...
In article , WaltBJ
writes
Slightly off track - the Germans did not seem to place the same level
of importance on recce that the Brits and USAF did. Me109s could (some
did) carry a camera in the aft fuselage like the recce P51s (F6?). A
lightened waxed Me109F or G would have a very good chance of
completing a recce pass on an in-and-out basis flown at max speed on a
curving descent or in-and-out at naught feet (prop tips above the wave
tips). It appears to me that the 86R was declared a 'clay pigeon' when
the LW found out Spits and Mosquitoes, appropriately modifed, could
get up that high. Why the LW didn't use 'hot-rodded' photofighters is
beyond me. Maybe they swallowed the 'XX' turned spies' reports as
gospel.
Walt BJ

Yes, the success of agents like 'Garbo' in feeding duff stuff to the
German High Command was remarkable.

Without wanting to go wildly off-topic, there was a programme on UK TV a
few nights ago ('Spitfire Ace') that had some very useful stuff on the
mentality of the RAF versus the that of Luftwaffe in 1940. The RAF
(through the vision and efforts of Dowding) had created a parless air
defence system, while the Luftwaffe had concentrated overmuch on the
lionisation of its individual pilots.

Honestly this sounds like Brits patting themselves on the back while
not looking at the strategic and tactical issues the Germans faced.
(sadly this is a sort of anasthetic as the UK goes down a sewer)

While I agree that we, as a nation, should be organising our lives
better these days, there is no doubt that the British air defence system
of 1940 was unmatched anywhere else in the world, and no-one, not even
the Germans, dare to claim that Goering's boasts of 1940 held water.

I think that by 1944 the Allies
had developed a war machine that was thorough enough to filter out most
flakey thinking and to concentrate on the real issues. If the Luftwaffe
in 1944 was still relying on the whims of 'gifted individuals' (Hitler,
Goering), who would have prided their own (uncriticised) judgement then
a lot of bad ideas would have good through and a lot of good ideas would
have been turned away.


German thinking was predicated on the need to fight a short and sharp
war as a nation sourunded by hostile countries. Avoiding a war of
attrition was essential and avoiding a war on German territory was
also essential.

The surrounding countries were only hostile because of Hitler's
belligerence - he could have been a peaceful leader had he so chosen.
As for laying odds on a short war - having contingency plans in case
your lightning strike does not work is fundamental to military planning.

The nation was physically to small and to devoid of
materials to handle a war in any other way and not loose thus
substantial offensive capability was emphasised but it was all up
front: resources were not devoted to reinforcements. This was the
thinking even before the Nazis came to power.

Germany had many resources to spare in the early years of the war.
Their industry was still working single shifts until things got really
bad. While Hitler was telling the German people about how well things
were going, Churchill was telling the British that we had to get a
wiggle on or lose - and our industry went to 100 percent from 1940
onwards.

Much of the German work on Microwaves and Proximity fuses (which
inspired British research)

Um...they told us about their work in these fields?

was suspended because the anything that
could not be ready in 2 years would be a waste.

Not a waste, a strategic error - no-one to blame but themselves.

It seems that at
this point that many of the German might have beens got caned.
Examination of this period is perhaps where it might be said that
Germany's technical may be said to lie. It migh also just lay in the
fact that Germany lacked the resources to develop them.

Poor prioritization - no-one to blame but themselves. The proximity
fuse was a small printed circuit that any small group of radio men could
have taken forward - there was no great industrial effort needed here.

The Tiazard
commision handed the proximity fuse and magnetron on a platter for the
USA to develop. The Germans just culled.

Good prioritisation on Tizard's part - hand the designs over to the
people who can mass produce immediately.

The excelent Freya and Wurzburg Radars were not integrated into a
defensive system because the bomber naviagation aids were considered
more important.

Integration was a matter laying telephone connections and training a
limited number of staff. If you have started a war, and it has gone
pear-shaped, and your efforts have simply created a hostile world around
you, air defence should then be recognised as a priority. After 1942
the allies were no longer fighting a war dictated by German initiatives
- they were fighting according to their own.

Cheers,

Dave

--
Dave Eadsforth