Bf 109 G range and endurance

[Angus]

Ahh, ok. Gotta find more on that, all interesting stuff.
Oh, I found at least one speed record. A modified P51, yes, with a Griffon made 499 miles in 1979.

[MiloMorai]

Angus, here is a pic of the V-13



The Bf109R(Bf209)



An attempt was made to turn the 209 into a fighter but it was a dud.

[Guppy35]

Originally posted by VO101_Isegrim
I wonder why even British documents give the Spitty`s 20-30% shorter ranged than 109s on the same amount of fuel then?

Which appears to be quite logical, given the Spitty always required more HP to haul itself around at the same speed than the Hundredneun, and Merlin`s specific fuel consumption was not so good as the DBs.

Perhaps these are "dry tank figures", ie. no reserves? Do you know the other details?

BTW, this is also from those Australian archieves :

http://www.x-plane.org/users/isegrim/FvsF/9-MkVIIIdive-restriction.jpg
http://www.x-plane.org/users/isegrim/FvsF/7-diveprohibition.jpg

I wonder if Guppy/Dan knows more about this, he said something similair about Spits over Normandy, iirc loosing wings when bombs were left attached in dive bombings.

Sorry I missed this so I'm late to the question.

Mk VIII had the same Universal wing that the Spit IXs had prior to Normandy when they first started dive bombing in earnest.  It was some of the 453 Squadron and 602 Squadron  that had the wings fold up when the bombs failed to release as they pulled out of thier dives.

The E wing was strengthened because of this.  The 3 bomb Spits are using E wings as are those carrying rockets.  These would be the Spit IXs and XVIs that equipped much of 2 TAF on the continent post D-Day.

The VIII never got that wing so it would make sense they would not use it in that role because of the Universal wing.

Just speculation on my part, but I would imagine not having two machine guns outboard of the bomb racks made a difference too.  With the single .50 cal and 20mm inboard I would think there would have been less stress on the wing.

Once again that's just me thinking out loud.  

I've not seen photos of VIIIs with the wing racks outside of the one included.  This is a 1945 image from the Med and shows a clipped VIII which is also fairly rare.  You can just make out the bomb racks outboard of the cannon.  

My assumption is this was not a common set up.

Dan/Slack

[Guppy35]

Originally posted by VO101_Isegrim
I wonder why even British documents give the Spitty`s 20-30% shorter ranged than 109s on the same amount of fuel then?

Which appears to be quite logical, given the Spitty always required more HP to haul itself around at the same speed than the Hundredneun, and Merlin`s specific fuel consumption was not so good as the DBs.

Perhaps these are "dry tank figures", ie. no reserves? Do you know the other details?

BTW, this is also from those Australian archieves :

http://www.x-plane.org/users/isegrim/FvsF/9-MkVIIIdive-restriction.jpg
http://www.x-plane.org/users/isegrim/FvsF/7-diveprohibition.jpg

I wonder if Guppy/Dan knows more about this, he said something similair about Spits over Normandy, iirc loosing wings when bombs were left attached in dive bombings.

Had a late thought on those pages you linked to.  First question would be is that August 45?  As in Postwar?  Those Aussie Mk VIIIs had seen considerable service by that point.

Second is that there were some problems with Spits in the Far East that were assembled incorrrectly with loose wing bolts, resulting in some collapsed wings.  The aircraft had arrived in crates and the crews assembling them messed up.   The word went out quickly to rectify that particular problem.

It might be this is a result of something similar too.

Dan/Slack

[GRUNHERZ]

Bleh, Bf109E is IMO one of the poorest fighter designs ever. Really a wasted opportunty with such a major redesign after the early Jumo 109s.

[VO101_Isegrim]

Originally posted by Angus
What speed record was put with the 109.??
I mean the 209 is no 109. It's a specially built little aeroplane with the sole goal of speed record breaking.
The "Speed" Spitfire was just a production type mod with an original production line engine.

If you mean one based on the early fighter 109 airframe, than it`s the Bf 109 V-13 test/recordplane. It was very much like the early 109B-E, with minor details like smoothened surface, enclosed openings and so on. It even had the external struts of the horizontal stabilizer.



On November 11th 1937, it set the world speed record of 610.95 km/h (379.39mph), with DB 601 Rennmotor III with Bodenlader, producing a peak of 1658 PS.



The record stood until the Me 209 broke it, with a much more powerful engine, DB 601 Rennmotor V. producing 2600 PS. Quite obvious why Supermarine gave it up, a few months later Messerscmitt`s recordplane (V-13) surprassed the expected results for the High Speed Spitfire. And even after that, all Mtt would had to do to break it again was to re-engine the V-13 with the 601 Re V. This would, as per my rough calculations, would increase it`s speed to 710 km/h, or 440 mph, with a more-or-less serial version of the Bf 109 fighter airframe.

So it was V-13 to which the 'World`s fastest fighter' title originates to, not the Me 209 (which on the other hand, anyway you look it, has the same design principles as the 109).

[VO101_Isegrim]

Originally posted by Nashwan
I suspect that's a Merlin 61 engined Spit IX.

The best fuel economy on the Spit VIII with Merlin 66 was found to be at 23,000 ft, the figures I posted above are at 20,000ft. With the much higher critical alt of the Merlin 61, I suspect best economy would be obtained much higher, around 27,000 ft.

I am fairly certain that this is a Merlin 66 engined Mk IX.

1, The suggested altitutude of the plane is 20 000 ft. We know the Merlin 66`s VDH was 20 000 ft, too.

2, Moreover, that 20 000 ft is the same altitude as the Mk VIII w. Merlin 66 as in your papers

3, The date is 2nd February 1943, ~the time the Mk IXLF was introduced. I am puzzled why the RAF would investigate the older Merlin 61 engined Mk IX F, which was in service more than 6 months by that time.

4, Also, the British intelligence doc, dated 15th Feb 1945, states 434 miles w. 85 gallons for the Spit XVI, Merlin 266 (should be rather identical to Spit VIII and IX)


[/QUOTE]
I doubt it's down to drag, if there was that much difference between the Spit VIII and IX, imagine the difference between the G2 you posted and the G6.[/QUOTE]

Agree, drag would make little difference, especially at very low airspeeds. Maybe 20-30 miles in full range. Probably the difference is in the trials testing enviroments. The Australian trials you quoted from, mention that :


CAUTION:  All the above corrections are only approximiate and apply for changes in temperature of the order of +-15 C or change in heights of +- 3000 ft from the measured values. The corrections do not apply at speeds below 150 mph ASI.


Apperantly, the numbers you posted are rather rough values and it`s noted there`s plenty of error margin with them. I don`t think the Merlin 66 and 61 would differ too much in fuel consumptions anyway.

Originally posted by Angus
Spitfire missions (mk V I think) could stretch up to almost 2 hrs WITHOUT drop tanks.

Oh, BTW, how much does the DB drink at full power?

You can cruise for VERY long periods with much reduced power and speed. Endurance is much dependent on the speed, and can be stretched considerably - of course there are limitations on that, hardly anyone would 'save' fuel at near-stall speeds, if he can expect enemy fighters in the area.

As for the DBs consumption, the table tells a lot. A comparable power for comparing the Merlin 6x series and the 605 would be +15 lbs Combat Rating and d 1.3ata Kampfleistung. The 61 would produce 1340 BHP at SL, and consume 150 gallons (=681 lit/h), the DB 605A-1 would produce 1310 PS and consume 400 liters, or in other world, the Merlin takes ~50% more fuel to develop the same powers at maximum output.

The highest fuel consumptions would appear with the DB 605 DC producing 2000 PS at 1.98ata, but even that was rather modest - "only" 650 liters/hour. Of course the D series were much improved models, with higher compression ratios as the A-series.

Wonder how much a DB 603 would consume though, never seen figures for it.

[HoHun]

Hi Isegrim,

>Wonder how much a DB 603 would consume though, never seen figures for it.

The DB603E-F running on B4 fuel consumed:

Sea level:

1750 HP - 565 L/h
1580 HP - 480 L/h
1375 HP - 410 L/h

1590 HP @ 6.3 km - 520 L/h
1490 HP @ 6.3 km - 450 L/h
1390 HP @ 6.0 km - 410 L/h
1170 HP @ 5.6 km - 330 L/h (205+10 g/HPh)

Data is for

Take-off/Emergency Power
Climb and Combat Power
Maximum Continuous
Continous Economical

respectively.

Source is the "Daimler Benz Leistungsblatt, DB603E-F B 4, 4.43" quoted from Dietmar Hermann's "Focke-Wulf Ta 152".

Regards,

Henning (HoHun)

[VO101_Isegrim]

Hi HoHun,

Thanks, it`s rather interesting. Appearantly, the 603E has almost the same charachteristics as the 605DB, with somewhat better consumption, which is what I expected from the increased volume.

I wonder how it related to the 603G in power output. AFAIK, the 603E was basically the same devlopment path as the 605AS, ie. mounting the development engine 603G`s supercharger on the 603A. The VDH`s are diffrerent though. Was that only because of different power outputs, was that because the 603G had better altitude performance? The latter had higher VDH, but sometimes this is misleading as it may that they have the same high altitude performance, just one engine is producing more power at higher boost at the lower levels.

The true beasts were the 603LA-1 and N engines, though.

[Nashwan]

I am fairly certain that this is a Merlin 66 engined Mk IX.

I'm absolutely certain it's not.

1, The suggested altitutude of the plane is 20 000 ft. We know the Merlin 66`s VDH was 20 000 ft, too.

Suggested altitude? You don't think that perhaps they picked 20,000 ft because it's a nice round number?

2, Moreover, that 20 000 ft is the same altitude as the Mk VIII w. Merlin 66 as in your papers

I should think the Australians thought it was a nice round number too. They also tested at 10,000ft. Now, tests at 10,000ft and 20,000ft, what can we
assume about the engine from the selection of those two altitudes?

3, The date is 2nd February 1943, ~the time the Mk IXLF was introduced. I am puzzled why the RAF would investigate the older Merlin 61 engined Mk IX F, which was in service more than 6 months by that time.

The doc you posted says "full endurance tests were carried out with a standard Spitfire IX"

Interesting you are now claiming the standard Spitfire IX before 2nd Feb (the time the report was signed off) was the Spit LF IX. Elsewhere you have claimed the LF IX did not get into service until March-April 1943.

Indeed, the performance tests on the Merlin 61 engined Spit IX on Mikes page say:

Performance tests were required on Spitfire F. MK.IX. B.F.274. This report deals with position error, climb, and level speed tests.

..................Preliminary results were forwarded to M.A.P. by letter, ref. A.A.E.E./4493/44/Gen-A.S. 56/50, dated 6th September 1942 and by postagram dated 17th September 1942.

So, preliminary results were obtained in September, full performance tests were done on 22nd October.

Now, the reason I am so certain it was a Merlin 61 engined Spit IX is:

The doc says trials were carried out at 20,000ft and 37,500 ft.  It gives a figure of 6.76 ampg at 20,000ft.

Spitfire The History gives the following under trials conducted on the Spit IX:

Boscombe Down 22 October 1942. BF274 Fuel Consumption Trials.  6.76 ampg range 450 miles, endurance 1.95 hours at 20,000ft. 6.03 ampg, range 375 miles, endurance 1 hour at 37,500 ft.

Look familiar? Look exactly the same as the figures in the doc you posted?

BF274 was the Merlin 61 engined Spit IX tested here:

http://www.fourthfightergroup.com/eagles/bf274.html

I've seen nothing to suggest Bf 274 was reengined with a Merlin 66, and indeed seeing the performance trials on Mike's page linked above were conducted with a Merlin 61 on 22 October, it would be rather strange of them to have swapped the engine in the intervening days, wouldn't it?

Agree, drag would make little difference, especially at very low airspeeds. Maybe 20-30 miles in full range. Probably the difference is in the trials testing enviroments. The Australian trials you quoted from, mention that :


CAUTION: All the above corrections are only approximiate and apply for changes in temperature of the order of +-15 C or change in heights of +- 3000 ft from the measured values. The corrections do not apply at speeds below 150 mph ASI.


Apperantly, the numbers you posted are rather rough values and it`s noted there`s plenty of error margin with them.

The corrections are nothing to do with the tests.

The "caution" you posted comes in a section headed

"Approximate effect of temperature deviations from standard ICAN conditions"

The next section is:

"To estimate cruising performance at constant engine conditions at other altitudes than given in report"

Both sections give corrections to apply to estimate what the differences would be if you flew in hotter or colder weather, or at different altitudes. They're "rules of thumb" to work out your range under different conditions.

In fact, the range table I posted is clearly labelled as being "standard atmosphere"

The chart I posted before gives the values for the Spit VIII with Merlin 66. As the only difference will be in drag and weight, with drag being slightly in the VIIIs favour, and weight in the IXs favour, they hold good for the Merlin 66 engined IX as well. The figures you posted are for a Merlin 61 engined IX.

As for the DBs consumption, the table tells a lot. A comparable power for comparing the Merlin 6x series and the 605 would be +15 lbs Combat Rating and d 1.3ata Kampfleistung. The 61 would produce 1340 BHP at SL, and consume 150 gallons (=681 lit/h), the DB 605A-1 would produce 1310 PS and consume 400 liters, or in other world, the Merlin takes ~50% more fuel to develop the same powers at maximum output.

At sea level. What about higher? The DB 605 is at it's most efficient at sea level, the Merlin at FTH. Try that comparison at Merlin FTH.

[Angus]

What really puzzles me about the 109's range possibly being more than of the Spitty is that 109's operating from the French coast had fuel problems swooping over Kent-London, while Spitties were, a year later, operating over Holland and Belgium.
In both cases there without drop tanks.
I remember that German pilots complained how quickly the DB ate up the fuel on high settings, hence the speculation.
On absolute full power I tend to think it's logical to assume that the DB ate more (not necesssarily pr.hp) because of its much higher volume.

Ohh, Izzy, thanks for the info on the 109 racer. I had not seen this before. If you have a good link or more pics please post.
The same with the early 109's, i.e. 109D. Interesting.

[VO101_Isegrim]

Originally posted by Nashwan

Now, the reason I am so certain it was a Merlin 61 engined Spit IX is:

The doc says trials were carried out at 20,000ft and 37,500 ft.  It gives a figure of 6.76 ampg at 20,000ft.

Spitfire The History gives the following under trials conducted on the Spit IX:

Boscombe Down 22 October 1942. BF274 Fuel Consumption Trials.  6.76 ampg range 450 miles, endurance 1.95 hours at 20,000ft. 6.03 ampg, range 375 miles, endurance 1 hour at 37,500 ft.

Look familiar? Look exactly the same as the figures in the doc you posted?

...

The chart I posted before gives the values for the Spit VIII with Merlin 66. As the only difference will be in drag and weight, with drag being slightly in the VIIIs favour, and weight in the IXs favour, they hold good for the Merlin 66 engined IX as well. The figures you posted are for a Merlin 61 engined IX.

Well, in that case I can only arrive to the conclusion that most Mk IXs were typically even less ranged than I originally thought.

Only a handful of Mk IXs were produced in 1942, with a range of 450 miles as the book and the report itself shows (Merlin 61).

The Mk IX LF, with Merlin 66, the main type of the Mk IX series, had less range due to the engine having poorer high altitude performance (where higher cruising speeds could more easily developed), of only 434 miles on internal fuel.

See below :




Now, this is for the Mk XVI, but it should be all identical to the MkIXLF with Merlin 66, the 266 being nothing else than a US-built 66. It makes sense, if you replace a high-altitude engine with a low altitude one, you will only get lower cruising speeds and lower range. There`s absolutely nothing in the 66 that would suggest it has better consumption than the 61, and even less that would suggest that the Spitfire had nearly the same range as the 109Gs - after all, the Merlins were considerably worser consumption ones than the Mercedes engines, and the Spitfire was considerably draggier than the 109G itself, carrying very slightly less fuel, too. Burning more fuel to travel slower won`t give you more or equal range, that`s for sure. This assumption was around for quite some time by now, only awaiting to be confirmed with that report (German GLA charts also show the same) And this is very much confirmed from the datas the two reports, and 2 data pages show, ie. roughly 50% more range on the 109G than on the various Spit versions on internal fuel.

Besides, the report itself you are quoting from gives absolutely no doubt about the Mk VIII ranges either, ie. Page 109  shows :

http://www.lanpartyworld.com/ww2/files/spit/8/109.jpg

Ranges:

-Main tanks (120gal), 230mph TAS : 740 miles, endurance 3.38h(?)

-Main + 30 gall (150 gallon), 220mph TAS : 960 miles, 4.25 h

-Main + 90 gal (210 gallon), 220mph TAS : 1265 miles, 5.7 h


You can see it very nicely agrees with the intelligence document above for the XVI LF.

At sea level. What about higher? The DB 605 is at it's most efficient at sea level, the Merlin at FTH. Try that comparison at Merlin FTH. [/B]

Hmm. Where did you took that the DB 605 was 'more effiecient at SL? Or that the Merlin is at it`s VDH?  The DB was equally effiecient at all altitudes, thanks to the variable speed supercharger.

You can do yourself any comparision if you like, whatever variables you want to use, it won`t make difference in that the DBs were considerably (30-50% more) fuel efficient than the R-R engines (and a bit better than any other German engine as well).

Gives you a hint why the internal tankage of the 109 never needed to be increased, yet it had more and more range as it developed. The Spitfire on the other hand had about the same (decreasing, in fact) range on all models, despite the fuel tankage was increased from 85 gallons by ~50% to 120 gallons by the end of the war.

Angus posted:

Ohh, Izzy, thanks for the info on the 109 racer. I had not seen this before. If you have a good link or more pics please post.
The same with the early 109's, i.e. 109D. Interesting.

Angus, the parts I took is from there, it`s more detailed:

http://www.adlertag.de/specials/worldrecord.htm

worth of checking out, too (in German, about 1st prizes the 109s won at the Zurich International Aircraft Meetings):

http://www.adlertag.de/specials/flugmeeting/flugmeeting.htm

[gripen]

Hm... At least here in Finland the  lowest practical cruise setting for the Bf 109G was 2100rpm at 0,9-1,0ata which resulted 1,5h endurance (including climb etc.). Anything lower settings resulted rough running (due to increasing dirt in spark plugs) and exhaust gases tended to enter in cockpit at low speeds; low cruise values  in the manual were more or less theoretical. In the combat conditions normal endurance was something around 1-1,25h; no one wanted to cruise at low speed in the hostile area.

Another thing to note is that there never was efficiency competion during WWII. Despite what ever was the fuel consumption of the Merlin, the merlin powered Mustangs and Mosquitos raced around occupied europe and the LW could do very little to catch them with piston engined fighters.

Regarding the efficiency of the DB 605, it should be noted that theoretically variable speed supercharger gives good efficiency at wide altitude range. But in the case of the DB 605, the adjusting system of the hydraulic coupling (simple barometric clutch) resulted that efficiency peaked at FTH, basicly advantages of the variable speed system were wasted in large degree due to this.

gripen

[VO101_Isegrim]

Originally posted by gripen
Hm... At least here in Finland the  lowest practical cruise setting for the Bf 109G was 2100rpm at 0,9-1,0ata which resulted 1,5h endurance (including climb etc.). Anything lower settings resulted rough running (due to increasing dirt in spark plugs) and exhaust gases tended to enter in cockpit at low speeds; low cruise values  in the manual were more or less theoretical. In the combat conditions normal endurance was something around 1-1,25h; no one wanted to cruise at low speed in the hostile area.

Yep, the same thing is true for all the other fighters as well, including the fact that the real life tactical enviroments decrease the available range even more. If air combat tooks place, consumptions skyrocket (ie. a Merlin 66 would consume 12.5% of the internal fuel in just 5 mins, reducing range by an equal amount), and range drastically shortens. This gives you an idea why ~450 miles on internal tankage (ie. Bf109E/all Spits) is so limited for real purposes, especially on offensive sorties.

Low RPMs usually generate rough running engines, but little more than that. Ie. from the Spitfire Mk VIII/Merlin 66 that has been already quoted, states :


"During the trials at 20k ft it was found difficult to run the engine at RPM below 2400 at full throttle, even though the boost was less than the limiting value (4lbs/sq.inch). "


etc.

Another thing to note is that there never was efficiency competion during WWII. Despite what ever was the fuel consumption of the Merlin, the merlin powered Mustangs and Mosquitos raced around occupied europe and the LW could do very little to catch them with piston engined fighters.

Rather rhetorical, ignoring the inconvinient parts and far from the truth. Statements like in the last sentence become extremely comical in view of facts like that Merlin powered Mosquitoes, operating initially in daylight, suffered twice the loss percantage from those LW fighters that 'could do very little to catch them'.. They, like all the oridnary bombers, had to operate under to cover of darkness, where they would only face the slower nightfigters, and even that wasn`t life insurance: daylight Mosquitos operating in the Bay of Viscay took their losses even from rather slow heavy fighters like the Ju88C which was even slower than a Hurricane.
It becomes an even more interesting in view of the official loss records, that state hundreds of Merlin P-51s being lost in every month after it`s introduction. As usual, a theory had born in someone mind, and regardless of the real world fact, he now seeks to force it on the reality he can`t accept.

Even looking on the technical side, it`s quite clear from the technical aspects of the engine, and planes, that there were nothing extraordinary in them. The Mustang wasn`t really any faster than the /AS powered Bf 109s of 1944, or the 190Ds. It`s great range was down to it`s great aerodynamics (beding equivalent to the 109s as showned) and the fact that it was loaded with insane amounts of fuel, which created plenty of trouble in service, including structural failers due to the rear tanks, installed in view of the Merlin`s taste. The range had nothing to do with the engine, in fact, it was outright against the fact the Mustang was Merlin powered, that engine being desinged for anything but not good fuel economy for an escort fighter - but there was nothing else available. I always think about what results could be borned from mating a Mustang airframe with high altitude DB engine. Aerodynamics would improve quite a bit with the more streamlined nose the inverted engine would enable now, and they could make the plane a lot lighter, or a lot longer range, with the fuel economy of the Daimler Benz now aiding the Mustang.

Regarding the efficiency of the DB 605, it should be noted that theoretically variable speed supercharger gives good efficiency at wide altitude range. But in the case of the DB 605, the adjusting system of the hydraulic coupling (simple barometric clutch) resulted that efficiency peaked at FTH, basicly advantages of the variable speed system were wasted in large degree due to this.

As for the 'simple barometric clutch', that was enough for the job. Nothing more complicated was neccesary, as it fullfilled the task perfectly, and could set the supercharger according to the exact amount of mechanical supercharging that was needed. If the plane was in high speed flight, this alone mean that dozens of horsepower being gained, thanks to the travelling aircraft compressed the air in the intake for free, AND that the supercharger control could notice this and work less hard when it was unneeded. The gain is quite obvious when plotting a DB power output chart vs. a fixed-gear supercharger system, that knows only ON and OFF.

[Angus]

I always thought that the Mossie had an exceptionally low loss rate. And at night, even better.
I'm sure Karnak has something more about this.