109 performance notes

[Kurfürst]

Thanks for the reference, Porta. I`ll look into it.

As for the Soviet test, manifold pressure was 1,3ata as per butch2k, and indeed the Soviet climb curves are in very close agreement with finnish and Rechlin climb data at 1,3ata.

"The Bf 109 G-1 Kennblatt data isn't corrected for compressibility. At 10 km TAS would be ~614 km/h."

How did you confirm that? The last I checked the 1943 Kennblat does not note this, neither the (2 page of the )Rechlin paper I have. However ~614 does seem to make  sense, if the compressibility notice is valid. It would comply well with the ~590kph claimed by those docs which are done with 109G with non retractable tailwheel. Given the -12kph penelty at SL (see Leistungzustammenstellung Me109G), it should be around 20kph at 10km... 614-20=595...

[Porta]

The Kennblat gives both Va and Vw values, and you can cheek that Vw is just Va corrected for density changes. By the way, 640 Km/h @ 10 km is a typo, it should read 630 km/h.i

[1K3]

about the 109G-14 speed

The 109G-14 speedgraph on this link http://www.spitfireperformance.com/spit14v109.html is the speeds we get on our AH 109G-14?

[Bruno]

Originally posted by 1K3
about the 109G-14 speed

The 109G-14 speedgraph on this link http://www.spitfireperformance.com/spit14v109.html is the speeds we get on our AH 109G-14?

Try reading the thread...

[Crumpp]

The Bf 109 G-1 Kennblatt data isn't corrected for compressibility.

Correct.

The Kennblatt will show exactly what the pilot should read on the gauge.

The Luftwaffe used two different types of airspeed indicators, Fahrtmesser 22231 and Fahrtmesser 22234, in the FW190.  Not sure whether both were used in the 109 series as well.

The allies did the same thing with their published data.  The speed shown is the speed the pilot reads in the cockpit.

All the best,

Crumpp

[Debonair]

Originally posted by Crumpp
...Fahrtmesser ...Fahrtmesser...

L0loLOLol0LOloL0loLOLol0LOl0L 0loLOLol0LOlOL0loLOLol0LOlOL0 loLOLol0LOl

[Krusty]

Grow *snicker* up, debonair, they're *giggle* posting perfect *snort* legitimate words here *snicker*

[gripen]

Originally posted by Crumpp
This is why people put you on their ignore list, Gripen.

You can also do that if you don't like my postings.
 

Originally posted by Crumpp

Is not a valid comparison for the simple fact the aircraft are different.  One is a prototype with a much larger percentage speed range.

It's up to you prove that the G-5/AS data is not valid. Using the data for the basicly similar G-6/AS posted by elkaskone, the claimed speed at 9000m is 660km/h while the tested G-5/AS did about 647km/h ie well within 3% tolerance.

Comparing the test data from Mtt and FAF for production G-1 and G-2 to the Mtt calculation gives more than 50km/h difference ie far above 3% tolerance.

Originally posted by Kurfürst

Some G-1 and G-2 test results for you at 10km, 1.3ata :

Rechlin's tested G-1, 640 kph.
NII VVS tested G-2, 645 kph.

So far no one has come up with the verifyable documentation that these are really flight tested values. Normal flight tested values at 10000m for the Bf 109G with the DB 605A are around 550-580 km/h (as an example Mtt and FAF data which you have).

Originally posted by Kurfürst
All in all, the G-5 airframe is at least 30-40kph draggier than the G-1 airframe at 10km altitude. The AS engine only made up for that. It's doesn't needs to be explained why a draggier plane needs more power to get similiar speeds.

Simply looking the low altitude speed values of the tested planes, the drag difference is less than 20km/h and the AS had roughly 200ps more available at 10000m and a better propeller for high altitude.

Originally posted by Kurfürst

I don't think you understand what Gebläsedruck means.

Please explain.

gripen

[Kurfürst]

Originally posted by gripen
Comparing the test data from Mtt and FAF for production G-1 and G-2 to the Mtt calculation gives more than 50km/h difference ie far above 3% tolerance.

[/B]

Different plane conditions, apples and oranges.

Tests done by Rechlin and NII VVS perfectly match Mtts calculations.

So far no one has come up with the verifyable documentation that these are really flight tested values.

[/B]

Nope, it's only you who deny the existence of these test flights, despite several sources veryfying that fact and identifying the plane themselves.

It's up to you to prove your claims that those tests weren't... err, tests.

Normal flight tested values at 10000m for the Bf 109G with the DB 605A are around 550-580 km/h (as an example Mtt and FAF data which you have).

[/B]

Just a little more sweating gripen, and you can made the 109G slower than the 109E. The Mtt data was done with a plane that had some kind of trouble with it's engines altitude output. You know that very well.

Simply looking the low altitude speed values of the tested planes, the drag difference is less than 20km/h and the AS had roughly 200ps more available at 10000m and a better propeller for high altitude.

[/B]

Well let's see.

A plane does 520 kph at SL with 1310 PS, and another 500 kph with the same power.

We want to make the 2nd plane just as fast as the 1st plane. The speed difference is 20kph, or 4%. The power requirement increases on the cube :

Speed difference : 520 / 500 = 1.04
Power required to get 500 to 520 : 1.04^3 = 1.125, or 12.5% more power required. 1310 x 1.125 = 1473 PS. Or an extra 131 PS.

Summary : For the 20kph (assumed true for the example ) draggier G-5 to get the same speed as the G-1, 131 PS extra power is required.

One can see very well why is there not much of a surprise to see why the draggier aircraft isn't that much faster than the cleaner one, despite more power.

[Crumpp]

It's up to you prove that the G-5/AS data is not valid.

Gripen,

Please point out where anyone claimed the Bf-109G5/AS data was not valid?

It is a new type testing and has a much larger percentage of error.

What was said is:

The data was valid or invalid as determined by Mtt for their prototype during the development of the Bf-109G5/AS. It would have been used or discarded in that program. That is what prototypes are for in the first place!

What's invalid and ignorant is your attempting to draw conclusions about the accuracy of Mtt calculations by comparing the Bf-109G1 production machine calculations and the flight test of a Bf-109G6/AS prototype.

Comparing the test data from Mtt and FAF for production G-1 and G-2 to the Mtt calculation gives more than 50km/h difference ie far above 3% tolerance.

BTW Gripen, VDM 9-12159 on WNr 26108 is the standard Bf-109G VDM propeller for GM-1 installation.

All the best,

Crumpp

[gripen]

Originally posted by Kurfürst

Different plane conditions, apples and oranges.

No, these flight tested planes were standard production G-1s and G-2s as claimed for the Mtt calculation.

Originally posted by Kurfürst

Tests done by Rechlin and NII VVS perfectly match Mtts calculations.

So far no one has come up with the verifyable documentation that these are really flight tested values. To put it simple: No documentation, no proof.

Originally posted by Kurfürst

The Mtt data was done with a plane that had some kind of trouble with it's engines altitude output.

There is no claim about problems with supercharger in the report. The reached FTH is quite typical for summer time testing and within normal variation as given in the Erla set.

Originally posted by Kurfürst

A plane does 520 kph at SL with 1310 PS, and another 500 kph with the same power...

The tested G-5/AS did 507km/h at 0m with about 35ps less than the Mtt tested G-1 which did same speed. The MT-215 did 523km/h and the reference G-5 did 506km/h at same power setting. And this tells nothing about efficiency differences in the propeller efficiency at high altitude.

Originally posted by Crumpp

Please point out where anyone claimed the Bf-109G5/AS data was not valid?

Your post 11-19-2005 02:22 PM:

"Is not a valid comparison for the simple fact the aircraft are different. One is a prototype with a much larger percentage speed range."

The G-5/AS performance data (prototype) is well within 3% variation claimed for the AS type type aircraft.

Originally posted by Crumpp

What's invalid and ignorant is your attempting to draw conclusions about the accuracy of Mtt calculations by comparing the Bf-109G1 production machine calculations and the flight test of a Bf-109G6/AS prototype.

It's fully valid showing the tested performance of the specialized high altitude aircraft with high altitude engine and propeller compared to the calculated performance of standard aircraft with standard engine and propeller.

gripen

[Kurfürst]

Originally posted by gripen
So far no one has come up with the verifyable documentation that these are really flight tested values. To put it simple: No documentation, no proof.

I'd express it more precisly :

Gripen so far no one has come up with the verifyable documentation about  these claims of his. To put it simple: No documentation, no proof - just of obviously biased zealotry.

And since you started your claims with a lie about the true conditions of the Mtt datenblatt, and you are very selective which tests, regardless of the noted conditions, are to be worshipped, and which are to be neglected and dismissed, which happen to be the ones that disprove your claims, I think we can just safely ignore all what you say. I don't even see a danger of someone actually believing that cr@p, it's that much in-credible.

[Crumpp]

Try understanding what you read, Gripen.  If you have questions please ask.  However once again your assumptions are killing you.

is not a valid comparison for the simple fact the aircraft are different. One is a prototype with a much larger percentage speed range."

Nothing in that sentence says anything about the Bf-109G5/AS protoype data not being valid for Bf-109G5/AS develpment.  IN fact the report recommends further development of the DB605AS.

That sentence says your comparision is not valid.

 

It's fully valid showing the tested performance of the specialized high altitude aircraft with high altitude engine and propeller compared to the calculated performance of standard aircraft with standard engine and propeller.

Now your adding to the ignorance.  Changing to a generally more efficient prop does not necessarily mean a level speed increase.  For example, flight testing the wide chord wooden prop on the FW190A showed a drop in level speed but greatly increased climb.  

Just changing propellers on the same aircraft can have a dramatic effect on speed.  Here in this flight test, we see the variation in speed at a given altitude of the exact same aircraft flown with 5 different propellers:
 

You simply do not have enough data on the propeller to make the kind of sweeping judgement your trying to conclude.

You are  attempting to draw general conclusions about Mtt's performance estimate accuracy based off standard production estimates of one variant by cross checking it with flight tested information from a completely different variants prototype.

A comparision which is ignorant.

All the best,

Crumpp

[Kurfürst]

Some note on the propellors, I possess some flight testing results for the 109K with four different propellors mounted, including the 12087 of the early 109G, and the 12159 of the high alt engines 109G/Ks, like the G-5/AS. There was also more advanced forms of these two tested.

The speed difference between the 4 props was rather minimal, 5-10 kph max between the best and worst, on the same airplane.

[Angus]

Rather close to the max speed specs of other props I have seen Kuffie.
Sometimes, climb rate would be affected more I belive.