Bf 109 G range and endurance

[phookat]

Originally posted by gripen
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.

I understand, but this again is in the realm of facts, to be proven or disproven.  Not anecdotal information.  I would say, though, that if a flight test was indeed conducted while flying a real 109 at a certain altitude at a certain fuel consumption, then it was certainly within the 109's flight envelope.  And 210 mph at 18k certainly sounds believable to me, I don't see why it would be impossible to fly at that speed.

Again, the purpose of this is modeling in AH or elsewhere.  If real pilots used the plane differently, at different cruise settings for example, that doesn't change the modeling in AH.  Hell, we usually run around at 100% right?

Now, if you believe the above figures are entirely calculated rather than based on a flight test, then that is another matter.

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

Nothing wrong in that, as long as the discussion is objective.

[gripen]

phookat,
The question is not if it's possible to fly 210mph at 18k  but if it's possible to fly 210mph at 18k using unknown power setting which results 10mpg. I don't know the answer.

gripen

[phookat]

Originally posted by gripen
phookat,
The question is not if it's possible to fly 210mph at 18k  but if it's possible to fly 210mph at 18k using unknown power setting which results 10mpg. I don't know the answer.

Still don't understand.  If the data you linked to was a result of a flight test, clearly it must be possible, no?  Whatever the power setting was...

[gripen]

phookat,
A plane can do 210mph at 18k by using various power settings ie rpm, MAP, mixture, etc and mpg value depends (among other things) on these settings. In the case of the Bf 109G most economical cruise setting had to set manually. Isegrim's data does not specify power setting nor it does not specify if the data is tested or calculated (it might be from captured documentation). A simple calculation gives fuel consumption 115l/h so the setting must be for very low power and I don't know if the Bf 109G could do 210mph at 18k by using such setting.

gripen

[phookat]

Originally posted by gripen
Isegrim's data does not specify power setting nor it does not specify if the data is tested or calculated (it might be from captured documentation).

A valid question.  But my suspicion is that it is tested, since it is fairly easy to test for.

Originally posted by gripen
A simple calculation gives fuel consumption 115l/h so the setting must be for very low power and I don't know if the Bf 109G could do 210mph at 18k by using such setting.

If it was a theoretical (based on engine tests and wind tunnel drag for example), then I think they would have thought of this matter.  In fact this is the crux of what they would be calculating, and surely they would know if that fuel consumption corresponded to too low a power.  If they didn't know that, then they have nothing to calculate with!

But if it was from flight test data (more likely IMO), the only way to deternime the range is to know exactly what the fuel consumption is at 210/18k.  How else could they have possibly calculated it?

Either way, I don't see a reason to doubt this information.

[gripen]

Originally posted by phookat
A valid question.  But my suspicion is that it is tested, since it is fairly easy to test for.

Actually testing fuel consumption, range and endurance is not fairly easy, special equipment and lot of flying is needed. As an example look Australian tests on Spitfire and Mustang. In the case of the captured equipment  testing is more difficult because the settings are not known  unless some documentation is available and flying time is limited due to lack of spares  etc.

Originally posted by phookat

If it was a theoretical (based on engine tests and wind tunnel drag for example), then I think they would have thought of this matter.  In fact this is the crux of what they would be calculating, and surely they would know if that fuel consumption corresponded to too low a power.  If they didn't know that, then they have nothing to calculate with!

Nonsense, the report  was created in field conditions in Africa and they certainly had no wind tunnel or engine testing stand like in the RAE.  Actually, it's very rare to see fuel consumtion tests on captured equipment, specially in the case of the fighter even if special equipment might had been available.

Originally posted by phookat

But if it was from flight test data (more likely IMO), the only way to deternime the range is to know exactly what the fuel consumption is at 210/18k.  How else could they have possibly calculated it?
 

Nothing indicates that they really tested these. Much more likely is that they just copied values from the German documentation. Or are saying that they loaded a captured plane with bombs and external tank to determine range?

Originally posted by phookat

Either way, I don't see a reason to doubt this information.

Well, it's up to you what you want to believe. The German documentation on cruise settings for Bf 109G was found to be quite unpractical here in Finland  and FAF created their own settings for service. I see lot of reasons to doubt Isegrim's data.

gripen

[phookat]

Originally posted by gripen
Actually testing fuel consumption, range and endurance is not fairly easy, special equipment and lot of flying is needed.

Hmm, OK.  Still don't see how this would be so hard.  You could do it with a fuel flow meter, and if they didn't have those you could just fly until the tanks were almost empty a few times (to take into account wind etc).  Even if it was hard presumably they did it anyway, but perhaps not with captured planes.

Originally posted by gripen
Nonsense, the report  was created in field conditions in Africa and they certainly had no wind tunnel or engine testing stand like in the RAE.  Actually, it's very rare to see fuel consumtion tests on captured equipment, specially in the case of the fighter even if special equipment might had been available.

Yes, I did not realize you were quoting a captured report.  In that case clearly there was no theoretical calculation involved.

 

Originally posted by gripen
Nothing indicates that they really tested these. Much more likely is that they just copied values from the German documentation.  Or are saying that they loaded a captured plane with bombs and external tank to determine range?

Presumably they didn't--but I would imagine that the Germans *did*, to come up with that documentation.

Originally posted by gripen
Well, it's up to you what you want to believe. The German documentation on cruise settings for Bf 109G was found to be quite unpractical here in Finland  and FAF created their own settings for service.

I can think of plenty of explanations for this, such as they may not have wanted to risk landing with near-empty tanks.  Or they just wanted to keep their speeds up to have an edge upon engaging an enemy.  Tests tend to eliminate variables, while anecdotes create them.  I still maintain it's best to compare test to test.  Of course test conditions may be different and results have to be normalized for comparison, but for modeling purposes each test combined with its conditions is IMO far more reliable than other information.

[Angus]

And logbook entries. Do they count as anecdotal or better?

[phookat]

Originally posted by Angus
And logbook entries. Do they count as anecdotal or better?

Wrong question.  The right question is: are they objectively applicable?  And the answer is to be determined on a case-by-case basis.

[Angus]

I guess than, that case by case collides with Izzy's calculations.

[HoHun]

Hi Angus,

>I guess than, that case by case collides with Izzy's calculations.

It seems that the distance from Manston to Bruxelles is about 230 km, which as shown above would be in convenient range of a Me 109E, and I'm sure in convenient range of a Spitfire II, too, so I'm not convinced there's a contradiction at all.

By the way, I just learned that there were special "long range" Spitfire units using Spitfire IIs with a non-droppable tank under one wing. (The pilots didn't like this configuration, for obvious reasons. :-)

Regards,

Henning (HoHun)

[Angus]

230 km each way with perfect navigation. Then one has to think off unfavourable winds and combat situation. Mk V's were on these missions as well.
Anyway,that fuel burn chart was nice

[phookat]

The same question comes up.  Do you the conditions at the time the flight occurred?  Where they fully documented at the time?  Until you do, such data is not objectively applicable.  Any more than a 109 pilot saying he could outturn Spits.

[Angus]

I disagree. There is a stage between those two.
This is just about aircraft frequently getting to a certain location and back under different cirkumstances. If your calculations say this is not possible, they must be wrong, for they are calculations against several actual occurances.
Range is in this sence a much more absolute thing than ever more flexible things as turning for instance.

What we do know is this.
Those missions took place at SL, in all sorts of winter conditions, partly under full boost, and ranged all the way into mid-Holland.
I never heard of the Mk II's extra tank,but most of the missions actually were flown with the Mk V without tanks.
Later on, I recall missions with bomb loaded and wing clipped MK V's.

[VO101_Isegrim]

Well I think it`s best to save the time debunk all the sillyness of Milo Morai, Gripen, Nashwan (and to a lesser extet, Angie).

To you, I can only say it doesn`t matter how much you bark, it only matters what proof you can show on your side.

You bark a lot, show no facts.


So let`s just concentrate on the facts, the rest of us.


First, the excerpt of a British Middle East report on a captured 109G-2/trop in poor condition (malfunctioning radiator control, .50 damage from P-40, tropical filter installed).




Altough some unquestionable authorities on this subject lately set their sails on repeating that this must be only thoeretical, calculated data, note that it says "the above figures supersede all previous estimates". Well, this must be a really-really better estimate than those.

Now let`s go on. Rather similiar range figures are being repeated in British intelligence docs in 1945, generally referring to the '109G', both 7.92mm and 13mm armed versions:




Furthermore, let`s see how this fits in the picture when compared to official German figures posted by their Air Ministry:



German data of the GL/A. Notice the 109F given to have a range of 1600km/993miles with droptank, at a somewhat higher (and less economic) speed.

The 109G-1s ranges are 'foreseen to be an improvement' over the 109F-4`s range of ~1000 miles with a droptank.

Let`s rehearse.


British test doc gives the 109G-2/trop`s range as 1215miles with a droptank (with some reserves included appearantly)

Another British intelligence doc states 1000 miles range for the overall 109G series.

An official German type sheet states the 109G-1`s range will be better than 1000 miles with a droptank (F-4`s).

Everybody can draw his own conclusions based the number of evidence I have posted.