109 e4 performance

[Robo.]

Originally Posted by Crumpp

However there is no good reason to believe it is anything other than what Mtt says, the mean performance. They knew much more about their aircraft design than any of us and were being paid to deliver those aircraft. Misrepresenting the mean would have been quickly noticed by the customer.

There is a very good reason to take their own graphs with pinch of salt just like the tests of captured Emils etc. Just because they're the manufacturers! This is exactly the same all over the world, at anytime, even in 1940's Germany as long there are human beings involved in the process.

It is just matter of opinion if you decide to take Mtt numbers as granted and sacred OR if you take more critical and suspicious approach just like I happen to have taken. I actually believe these Mtt numbers completely if they reflect the Aa at 1.45ata 2500RPM, which is due to be confirmed. It's weird how some of you guys started jumping up and down just because I dared to challenge the Mtt chart (calculated theoretical stuff, pretty much correct, but still not real life data and it has got massive space for variations...)

Interestingly, this discussion keeps revolving around these unlucky Mtt files, but no one contributes anything to the actual topic - E-4 performance in the sim and how to get it 'right'. What is this topic in here for, then?

[Crumpp]

Nana, I think there is good reason to believe that the REAL obtained mean value was not on the centre line of the spec bandwidth. This is not how engineering works. The mean value of a produced thing is NEVER on the targeted nominal performance. My years in the engineering business taught me that. I have NEVER seen one produced thing that had its mean value on the nominal spec.

There is no credible reason to doubt Mtt's figures in the absence of facts.

Crumpp says:
They knew much more about their aircraft design than any of us and were being paid to deliver those aircraft. Misrepresenting the mean would have been quickly noticed by the customer.

Well I think the Mtt facts (the 13 tested planes that are on average below the centre spec line - 10 out of 13 are below = average < centre spec line) are there that support my opinion that for the 109G the type was on average below the centre spec line and there is good chances that this is the case for any type coming from this company hence also for th 109E.

You insist that these 13 are not representative and keep arguing that it should be the centre spec line that should be taken as the mean value for the 109 while there is absolutely NO fact that consolidates this opinion. Please provide us with some data from test flown 109E that reach 500 kph and more but beware we need data from several individual tests with this result to support your view.

PS: The centre spec line has nothing to say except that this is just the middle value between the acceptance bandwidth. We have no clue that Mtt ever attempted in fact to reach 500 kph (that is this is the aimed nominal value they took into account during the design process) and there is NO facts supporting that the average 109E ever achieved this performance.

[Robo.]

Originally Posted by Crumpp

There is no credible reason to doubt Mtt's figures in the absence of facts.

There is a good reason to challenge any data if we really care to have the planes modelled correctly, e.g. close to the so called 'real life'.

First of all, the actual limit range is massive. (btw. I very much agree with Stormcrows insight regarding the tolerance and actual treshold being slightly lower that 500km/h, which plus some subtle variation within that treshold as he suggested would be a superb feature! (for all planes obviously))

Also, there is no details such as what engine and what settings exactly would result in that top speed. If thats DB 601Aa at full power (1.45ata / 2500 RPM), that is absolutely OK.

[TomcatViP]

Originally Posted by Robo.

...which plus some subtle variation within that treshold as he suggested would be a superb feature! (for all planes obviously))
....

It's alrdy in the game I think at least for the Hurri.

[Robo.]

Originally Posted by cheesehawk

I think its a combination of both sides, you're defending a shot down plane fixed with non-experts using French parts and who knows what else,

If that message was ment for me, then no, I am challenging both Mtt and French test and take them with pinch of salt for good reason imho. I am certainly not defending the French test, please read my previous posts.

I have the impression that this is a never ending discussion.

The fact is any tests can and should be taken with a grain of salt. But what other evidence do we have in order to come to a conclusion what should be the max speed for the 109E?

Currently we are turning in circles.

There is the fraction that wants the centre spec line as the reference, others like me say we should take the scattering of the 13 planes from the 109G series with respect to the 109G specs, transpose it to the the 109E and its spec (by miracle we will find ourselves in accordance with all test data of the 109E known to us) and take the mean value. That's what I as an engineer would do (and many other colleagues too I am certain). This mean value would be about 485-490 kph. Perhaps in the future we can have a Gaussian curve with an appropriate sigma (my suggestion 1 sigma = 4-5 kph) so that individual planes may differ slightly.

Perhaps in the far future we can have (offline at least) planes subjected to wear so they will loose a little of their performance with time (for instance if they have had to undergo repair or so).

[robtek]

What i still don't get is: where comes the "agreement" from that the speed was reached with a DB601Aa from?

Wasn't the Aa the export version with more hp but lower full throttle height?

A feature absolutely not needed where most fights started well above 5000m.

[Crumpp]

support my opinion that for the 109G the type was on average below the centre spec line

That is not proof. It is just the reality of aircraft. Even something as simple as an annual has resulted in the need for a complete readjustment of my propeller rpm to reach rated performance.

That my airplane flew below standard on its test flight after annual does not mean it is a sub performing example.

Crumpp says
Keep in mind it is probable that most aircraft off the assembly line will have squawks that need addressing.

Just because a new aircraft has squawks does not mean it will be rejected. Most are minor adjustments that will be taken care of relatively quickly.

I would expect the majority to perform slightly below average until those squawks are fixed. You can also have optimistic performance that represents a squawk that must be fixed. An adjustment of the propeller governor, fuel metering, timing, etc...can have a large impact on performance.

I am going to bow out and let you guys continue without my input.

[JtD]

It's interesting to see that while the specified speed was 656 km/h, the average of the measured performance was just 643 km/h. And it's still not up to specification when excluding the unacceptable values.

From my experience, this is what you can typically expect. It's human nature to do things as good as necessary, and if both +5% and -5% are as good as necessary, you'll find the more items near the -5% limit.

But I think Kurfürst has nailed it in the meantime: If the in game speed of the 109 E at sea level is below 475 km/h or above 525 km/h, it is wrong. Everything else is a matter of taste.