109 e4 performance

[Robo.]

Originally Posted by Crumpp

That is the best standard in the aircraft industry.

That is the performance Mtt's guaranteed by contract to the RLM its airplanes would perform. If an airplane did not fall within that +/- 5% then the RLM did not pay for it or accept it as one of the airplanes it purchased from Mtt.

Each airframe was test flown before it was accepted for Luftwaffe service and it had to meet that minimum specification.

Alright, I think we should use the data specified by the manufacturer when they tried to get that contract then.

[SG1_Lud]

Originally Posted by Robo.

Alright, I think we should use the data specified by the manufacturer when they tried to get that contract then.

If it is a question of credibility, between the manufacturer data and that "test" done in France, I trust more in the manufacturer's, for two reasons:

1) if you read in the detail the french test, is clear that it was done far from the conditions you want for a test.

2) I havent heard of a single LW report complaining about the manufacturer's specifications being wrong.

Cheers!

[SNAFU]

Well, manufacturers tend to stick with margins specified and use them, if they have the quality system giving them the ability to mangage the narrow gab. If 500km/h +/-5% on ground level was specified, I would expect the standard plane to leave the shops testified to be able to reach 475km/h, but not one km/h more.

[Crumpp]

able to reach 475km/h, but not one km/h more.

Really???!!!?

[Robo.]

Originally Posted by SNAFU

If 500km/h +/-5% on ground level was specified, I would expect the standard plane to leave the shops testified to be able to reach 475km/h, but not one km/h more.

That is my opinion, too.

Originally Posted by LUD

2) I havent heard of a single LW report complaining about the manufacturer's specifications being wrong.

They wouldn't complain to you, dude with a 109 in the avatar

[Crumpp]

I havent heard of a single LW report complaining about the manufacturer's specifications being wrong.

It definitely gets fixed if it does occur. Focke Wulf had an issue with one of its subcontractors, Dornier (NDW) not meeting specifications.

It was discovered when the Luftwaffe was rejecting a large number of aircraft. The complaint was excessive vibration and fuel consumption. It generated several reports on the issue and was fixed promptly. It caused NDW to suffer greatly increased oversight and they almost lost their contract.

[Crumpp]

If 500km/h +/-5% on ground level was specified, I would expect the standard plane to leave the shops testified to be able to reach 475km/h, but not one km/h more.

That is not it works building airplanes. You can get close to the lowest common denominator building a toaster maybe?

[Robo.]

Originally Posted by Crumpp

It definitely gets fixed if it does occur. Focke Wulf had an issue with one of its subcontractors, Dornier (NDW) not meeting specifications. (...)

That's fine information regarding the inferior quality of a component supplied by 3rd party, but does not say anything about the overall performance, especially top speed. Of course, quality of the components matters a lot and if they all meet standards, it is very likely that the aircraft as such will meet them. BUT manufacturer's specifications are more likely to be a target, not necessarily reality. I highly doubt that they would stretch brand new engines to see if every plane goes 500 km/h on the deck, returning them to the manufacturer if they wouldn't. If the engine ran fine and within specs, they were happy. It was close enough to the specs, some particular aircraft met them OK, but as for the sim, -4 or -5% seems to be reasonable.

Originally Posted by Crumpp

That is not it works building airplanes. You can get close to the lowest common denominator building a toaster maybe?

The point is that the graph posted by Kurfurst is what the manufacturer would like to achieve, but we all know how it goes in real life, do we? I agree that in Germany it was more strict than e.g. in Russia or Italy () This is my opinion and I respect yours. But who are we?

[Kwiatek]

There were 2 types of engines used by LW - Db601A and DB601Aa which had little different power output.

Db 601A - sea level
1 minut emergency (2400 RPM at 1.4 Ata) - 1100 PS
5 minut emergency (2400 RPM at 1.3 Ata) - 990 PS

Db601Aa - sea level
1 minut emergency (2500 RPM at 1.45 Ata) - 1175 PS
5 minut emergency (2400 RPM at 1.35 Ata) - 1015 PS


Standart 109 E-3 with Db601 at 1.3 Ata 2400 RPM (5 minut power) reached at sea level - 467 km/h ( radiator 1/4 open)



http://kurfurst.org/Performance_test...MP16feb39.html

It is good agreement with Swiss 109 E-3 Db601Aa tested with different propellers:



Sea level speed - 467 km/h with standart propeller

Quite close with tested captured 109 E-3 by French :



So it could be that with Db601 Aa at 1.45 Ata 2500 RPM (radiator close?) - 1 minut emergency power 109 E-3 reached 500 km/h like in German manual:




Interesting is that at low level 109 E-3 need 5-minut power output with speed 467 km/h comparing to Spitfire MK1 at 6 1/2 lbs ( 1/2 hour limit) - 455 km/h. Db 601A had 990 HP at 1.3 Ata where Merlin III had 880 HP at 6 1/2 lbs at sea level.

Originally Posted by SNAFU

Well, manufacturers tend to stick with margins specified and use them, if they have the quality system giving them the ability to mangage the narrow gab. If 500km/h +/-5% on ground level was specified, I would expect the standard plane to leave the shops testified to be able to reach 475km/h, but not one km/h more.

concerning this: I think it would have been a dangerous policy from an industrial point of view if they aimed at 475 kmh while they guaranteed 500 +/-25 kmh.

We know that during production of the plane (all parts, some coming from suppliers not under quality control of the Bayrische Flugzeugwerke) and the engine (all parts, some coming from suppliers not under quality control of Daimler-Benz) variations occur (that's why each part will have its own specs +/- acceptance margins). When all parts assembled it will lead to a performance that will vary from one plane to another. Now if they had aimed at being at the lower limit they would have ended up with planes that would not have met the specs and therefore increased the number of planes rejected by the customer. This is imho something that someone who wants to run his company profitable wants not to happen.

If one reads the chart by the French one should assume that they could have reached about 480 kmh on deck. At 500m they are at 494 kmh.