Bf 109 G range and endurance

[Nashwan]

But do tell why is this discussion so retarded? Why are you people comparing the minuta of fuel effieciency at X carb setting, y blower at z alt with such fanaticism?

I think that's just Isegrim.

He posted some test figures for the 109, that showed it could achieve up to 10 mpg. With that he hoped to show that the 109 had significantly longer range than the Spitfire (With Isegrim, proving the 109 was better than the Spitfire is an obsession. It has to have longer range, greater climb, higher speed, more powerfull weapons, etc. When the facts don't back that up, he just uses alternative facts)

I posted a chart showing the Spitfire could also get 10 mpg, under similar conditions. Isegrim, true to form, will now use "alternative" facts to prove it doesn't, despite a test report showing it does.

[Guppy35]

Originally posted by gripen
Guppy 35,
I don't know if the rear fuselage tank was used operationally in the Spitfire VIII  but such installation was certainly possible.

gripen

gripen.  I've looked long and hard for images of a fuselage fuel tank installation on a wartime Spit IX, XVI, etc.  I've never found one of a combat flown aircraft.

The image posted shows what would be seen, just behind the cockpit.

I spent a lot of time corresponding with a former 79 Squadron Spit VIII pilot who flew combat in the Pacific with the RAAF.  They did not have those tanks and it would have made the most sense for them to have them considering the overwater flying etc.  I have never seen a photo of a VIII with this installation anywhere and believe me I've looked long and hard as my quest for Spit range goes back to my AW days when I blew a gasket during a scenario where the Spit's got neutered.

It does come down to theoretical vs practical use and it just was not common practice to use the fuselage tank operationally.  I can't even find end of the war pics of XVIs with this installation.  Post war photos don't show them either.

Dan/Slack

[HoHun]

Hi Guppy,

> [/B]

Thanks for the picture, I wasn't aware the fuselage tank was recognizable from the outside!

With regard to ranges, Radinger/Schick's Me 109 book has some data on Me 109E/B performance.

It used a minimum of 0.48 L/km on the way to the target with a 500 kg bomb underneath and of 0.43 L/km on the outbound journey without the bomb. The minimum was achieved at 7 km at best economical speed.

Total fuel: 400 L
10 min climb (321 L/h): -53.5 L
10 min combat (321 L/h): -53.5 L
10 min reserve (260 L/h): -43.7 L

Fuel for cruise: 249.3 L => 580 km (for the pure fighter with no bombs loaded)

So that leaves us with a 290 km radius of action for the Me 109E.

Warm up, taxying and forming up in the air has not been considered in my rough estimate, but as I also neglected distance covered during the climb and range gained from gliding down from 7 km, the errors could compensate each other :-)

The interesting thing is that at full throttle, fuel consumption rises to 0.54 L/km, reducing combat radius to 231 km.

Regards,

Henning (HoHun)

[phookat]

Originally posted by Guppy35
It, at least in my eyes, comes down to theory (test data) vs practice (actual pilot/combat experience)

No, I would say "theory" is supercharger design, calculated fuel consumption, and the like.  "Practice" is flight test data.  Both are objective.  Anecdotal stuff is subjective, and doesn't belong in an objective technical discussion.

Originally posted by Guppy35
What it should do under ideal circumstances with the aircraft being flown by a test pilot and the aircraft maximized for results, is different from a production aircraft, being flown by a squadron pilot, under operational circumstances.

The goal of practical testing is to embody operational circumstances as much as possible while generating repeatable and objective results.  In fact, part of being objective is to make sure that tests are realistic.  Anecdotal information helps us determine proper test procedures, but cannot be used as the test itself.  Presumably the testers utilized anecdotal information to devise tests, since lives were on the line and they had to be as objective as possible.   Some pilot saying "I could catch Spits anytime" is not a proof of anything since another equally qualified pilot says "I could catch 109s anytime".

Originally posted by Guppy35
That's why, even though you could claim I have a Spit bias, I pointed out that gripen's comment about 160 gallons of internal fuel in a VIII isn't really accurate as they weren't flown in combat that way.  In testing, the claim can be made about that kind of range, but operationally it wasn't done.

True, and I appreciate the objectivity you lend to these discussions.  However, this is not anecdotal information.  It is objective fact, to be proven or disproven as such.  So it does belong in the discussion.  Differences between what was used in a test and what was used IRL should of course be considered, and their effects pondered.

Also, anecdotal information about what kind of equipment was used is in an entirely different class from anecdotes about a planes performance.  At least the former has some chance of being objective.

Originally posted by Guppy35
Normally you'd expect the WingCo's kite to be the best.  Whose Spit IX should I use to determine the particulars?  I'd like to use the brand new one that outran the others, but is that the norm or the exception?

There are waaaay too many variables in this situation, starting with the pilot's own recollection of specific details.  Just playing in the AH arena demonstrates this--even though we fly mathematically identical planes, then can seem to perform so differently depending on the circumstances.  So this is another reason why such anecdotal information should not be used in a technical discussion, or a discussion of how our planes should be modeled in AH.  It is unreliable and unconfirmable.

[phookat]

Originally posted by GRUNHERZ
But do tell why is this discussion so retarded?  Why are you people comparing the minuta of fuel effieciency at X carb setting, y blower at z alt with such fanaticism?

For that matter, why discuss anything with fanaticism?  But I think you are wrong, the discussion has been quite civilized.  If it's not an interesting subject that is another matter, and not the fault of the participants.

[phookat]

Furthermore, in this discussion I think both Guppy and Isegrim have been quite objective...contrary to some claims here, whose origin I simply don't understand.  Liking one plane more than another doesn't mean you can't participate in a technical discussion objectively.

[Angus]

Anecdotal stuff still applies when it was exercised on squadron size level, i.e. regarding range.
Such as Spitties going impossibly far without drop tanks

[Guppy35]

Originally posted by phookat
No, I would say "theory" is supercharger design, calculated fuel consumption, and the like.  "Practice" is flight test data.  Both are objective.  Anecdotal stuff is subjective, and doesn't belong in an objective technical discussion.



The goal of practical testing is to embody operational circumstances as much as possible while generating repeatable and objective results.  In fact, part of being objective is to make sure that tests are realistic.  Anecdotal information helps us determine proper test procedures, but cannot be used as the test itself.  Presumably the testers utilized anecdotal information to devise tests, since lives were on the line and they had to be as objective as possible.   Some pilot saying "I could catch Spits anytime" is not a proof of anything since another equally qualified pilot says "I could catch 109s anytime".



True, and I appreciate the objectivity you lend to these discussions.  However, this is not anecdotal information.  It is objective fact, to be proven or disproven as such.  So it does belong in the discussion.  Differences between what was used in a test and what was used IRL should of course be considered, and their effects pondered.

Also, anecdotal information about what kind of equipment was used is in an entirely different class from anecdotes about a planes performance.  At least the former has some chance of being objective.

 

There are waaaay too many variables in this situation, starting with the pilot's own recollection of specific details.  Just playing in the AH arena demonstrates this--even though we fly mathematically identical planes, then can seem to perform so differently depending on the circumstances.  So this is another reason why such anecdotal information should not be used in a technical discussion, or a discussion of how our planes should be modeled in AH.  It is unreliable and unconfirmable.

I understand what you are saying.  I guess what it comes down to for me is that you can't remove the human/pilot element from the discussion.  I also believe that too often in the discussions here, the numbers get twisted to support a point

Posting an image, more for the novelty I guess, but also to point out the human element.  I got it from a Spit driver I became friends with.  Part of his midwar time was spent as a service test pilot with Supermarine.  They took one of these cards along to record their observations on every production test flight on a new Spit.

Dan/Slack

[Angus]

Very Nice indeed.
Now we just need to have some filled out ones

[phookat]

Originally posted by Angus
Anecdotal stuff still applies when it was exercised on squadron size level, i.e. regarding range.
Such as Spitties going impossibly far without drop tanks

Something like that will show up in an objective test anyway.  The testers back then knew the basics...if their tests showed that the Spitfire had a range of 10 miles, they would suspect they did something wrong and retest.  Anecdotal stuff is so spotty...how far did they really go, what was the tailwind like, etc etc etc.  I'm not even scratching the surface, but there are simply too many variables to take this kind of thing seriously for a discussion.

[phookat]

Originally posted by Guppy35
I understand what you are saying.  I guess what it comes down to for me is that you can't remove the human/pilot element from the discussion.

To be practical, the inclusion of combat pilot information should not be considered just for its own sake, but rather when it can add value to the discussion.  In a discussion of how comfortable the cockpit was, for example, such information would be quite valuable.

Originally posted by Guppy35
I also believe that too often in the discussions here, the numbers get twisted to support a point

That may be true, but it is an entirely different issue.  If the numbers have been misinterpreted, the solution is not to say "but Chuck Yeager flew to the moon so you're wrong".  The solution is to point out what the correct interpretation of the numbers is, and why.

[gripen]

phookat,
My original point was simply that at least here in Finland practical endurance of the Bf 109G was found to be max 1,5h (with internal fuel). The lower power settings were found to be unpractical and therefore the data  Isegrim presented seems to be more or less theoretical and probably not tested. Infact I don't know if the Bf 109G could fly at 18k with power settings needed for that 725 miles range. I have some data on Bf 109G including German documentation and so far I have not seen any real test  data which supports Isegrim's argument.

Regarding the rear fuselage tank in the Spitfire VIII. Guppy 35 certainly knows this stuff better than me and I stand corrected; such installation was more or less theoretical (just like Isegrim's data).

Overall I wonder why discussions with Isegrim allways turn to Spitfire vs Bf 109 stuff.

gripen

[Angus]

Phookat "I'm not even scratching the surface, but there are simply too many variables to take this kind of thing seriously for a discussion."

If a Spitfire of a non-drop tank version gets shot down over mid-Belgium, it had to be able to get there, no matter what you calculate.

If slipper-tank equipped squadrons crossed the Med over malta and started fighting in Tunisia, they must have been able to get there, no matter what Izzy gets out of his calculations.

[phookat]

Originally posted by Angus
Phookat "I'm not even scratching the surface, but there are simply too many variables to take this kind of thing seriously for a discussion."

If a Spitfire of a non-drop tank version gets shot down over mid-Belgium, it had to be able to get there, no matter what you calculate.

If slipper-tank equipped squadrons crossed the Med over malta and started fighting in Tunisia, they must have been able to get there, no matter what Izzy gets out of his calculations.

Here's just one explanation: power setting at cruise.  Here's another: cruise altitude.  Here's another: what was the wind like that day?

Do you know what these were?  For certain?  Now find a similar anecdote from a 109 pilot, in which you know for certain that these conditions were the same.

Then we can have a comparison.

[joeblogs]

The following numbers are present a different measure of fuel economy for many WWII V12 engines - specific fuel consumption.

The advantage of this measure is that it tells you the absolute best the engine can do on the bench, which makes comparisons across engines a little easier to do.



Year refers to the year the data was published.

Schgr refers to the type of supercharger. "g" means geared, "t" means turbo, the number x.y refers to the number of stages and speeds respectively (Hence a Merlin 60 is a g2.2), "v" stand for variable speed as in the DB601.

Fuel refers to the US performance number rating system (octane+) of the time.

SFC refers to lbs (US) of fuel consumed per horsepower per hour.

Wartime Merlins & Griffons do appear more thirsty than their Daimler brethren, but get better after the war. At least one Packard Merlin does better (could it be the carburetor?). The Allisons vary considerably.

-blogs