109 e4 performance

[CaptainDoggles]

Originally Posted by Robo.

There is no disagreement at all. As you say, manufacturer calculated speeds in certain conditions, but he never verified them with flight tests.

I'm pretty sure we've just spent 4 pages establishing that not only did Messerschmitt conduct test flights to verify their numbers, but so did the RLM. Use logic for a second: If, as you say, nobody did tests between the aircraft coming out the door of the factory and going to operational service, then how did the RLM know they were getting what they paid for? How did Mtt know that the RLM wasn't trying to cheat them?

Answer: They did flight tests. We just don't have the documentation.

The main reason being it was not really possible, the data are simply theoretical speeds.

Are you seriously saying it was "not really possible" for Messerschmitt to conduct flight tests? These are not theoretical speeds, it's a requirement that Messerschmitt was obligated to meet.

but these speeds never achieved in any actual empirical tests (again, various reasons).

I see your agenda beginning to show. What you mean to say is: We don't currently have access to any empirical tests where this performance was achieved. Or perhaps: The (very very small) sample of aircraft that made their way into the hands of the Allies did not achieve rated performance.

[Kurfürst]

Indeed Messerschmitt did proof checking of their airplanes. I've only seen one such paper, this is for Erla licence-produced Bf 109Gs. You can see the nominal (guaranteed) performance with a thick line, and also the upper and lower tolerance on performance (+/- 3%) for acceptance.

The dots are measured values for 13 individual planes - some are a bit worse, some are bit above the specs, and there are couple that will be rejected until the plane is brought up to spec.



The story in short is, however, the nominal specs are guaranteed to be reached within limits. An aircraft is just like any product, the producer has liability to meet the agreed contract, no matter when, and where. In Germany, the LW had its own separate quality control organisation, the BAL. They were pretty strict right until the war's end. Reading Hans Fey comments on Me 262 testing, the lower limit for the Me 262 was 830 (nominal/guaranteed spec was 870 kph), they did accept planes down to 825 but that was it; anything lower would be rejected. And that was in 1945, when the Germans would need as many jets as possible.

http://www.lwag.org/forums/showthread.php?t=484

Now the bottomline: As shown in the Baubescreibung Me 109E document, the specs for the 109E were 500 km/h at SL and 570 km/h at altitude with 1.35 ata or full power and the DB 601Aa engine, within +/- 5 % of that for each individual plane. We have exactly that aircraft modelled in the sim, so E-1, E-3 and E-4 should satisfy these specs. If they are modelled different, its wrong, end of story.

[Robo.]

Originally Posted by Kurfürst

Now the bottomline: As shown in the Baubescreibung Me 109E document, the specs for the 109E were 500 km/h at SL and 570 km/h at altitude with 1.35 ata or full power and the DB 601Aa engine, within +/- 5 % of that for each individual plane. We have exactly that aircraft modelled in the sim, so E-1, E-3 and E-4 should satisfy these specs. If they are modelled different, its wrong, end of story.

They actually satisfy these specs on the very bottom end. They should certainly be slightly faster on the deck. My point is let's get some figures that might be acceptable for the sim for both Emil engines on all ratings, ideally for all rated powers mentioned in the chart.

Interesting info about the Erla Gs, seen that one before on your website. Does not say anything about top speed being tested on the deck and I can't read the doc good enough to see the actual ata settings etc.

[Robo.]

Originally Posted by Kurfürst

Now the bottomline: As shown in the Baubescreibung Me 109E document, the specs for the 109E were 500 km/h at SL and 570 km/h at altitude with 1.35 ata or full power and the DB 601Aa engine, within +/- 5 % of that for each individual plane.

That's for DB 601Aa indeed. The problem is obviously the huge tolerance of 50km/h - and also, I can't seem to find anything confirming the ata used to achieve that speed. Was it Bodenleistung or did they push it on 1.45ata? Do we know? Makes quite a difference.

Originally Posted by Kurfürst

We have exactly that aircraft modelled in the sim, so E-1, E-3 and E-4 should satisfy these specs.

It's not that easy I am afraid - the Aa and A-1 were slightly different. We don't know which engine is modelled in the sim for each subvariant. That's why I am trying to get some numbers together for both.

[Robo.]

Originally Posted by CaptainDoggles

They did flight tests. We just don't have the documentation.

Of course they did, but did they really strain a brand new engine to verify the max speed on the deck? If you have any further information about the tests conducted by RLM / BAL in order to accept an airframe they have paid for? That would be great to know, but using logic again, would their test pilots push the new a/c to its limits? I believe they would not and if the plane performed within limits, they were happy.

Originally Posted by CaptainDoggles

Are you seriously saying it was "not really possible" for Messerschmitt to conduct flight tests? These are not theoretical speeds, it's a requirement that Messerschmitt was obligated to meet.

No, I never said such thing. I never stated that Mtt failed to deliver what they were legaly bound to. I said they most probably did not perform extensive tests to prove our point. The fact is, no matter what test you look at, no aiframe ever managed to reach the speed in the Mtt chart. That brings you straight back to the beginning of this discussion.

Originally Posted by CaptainDoggles

I see your agenda beginning to show. What you mean to say is: We don't currently have access to any empirical tests where this performance was achieved. Or perhaps: The (very very small) sample of aircraft that made their way into the hands of the Allies did not achieve rated performance.

I've got no agenda at all, I only have interest in aircraft portrayed in the sim and I enjoy discussing them. I said - any many would agree - that the tests available are far from being representative (for various reasons). I also said that the Mtt data is theoretical and can be considered optimistic in relation to the real life performance. Many would disagree and I respect that, especially if that's supposed to be a performance of Aa engine on take off MFP ('1 rating) - fair enough.

I tried to get some figures to the respective rated power of both engines in question in order to establish some base. I find it interesting and I enjoy thinking about such details. There is nothing more to that, perhaps except my wish to have the a/c in the sim as close to the real thing.

What is your opinion on the actual figures, CaptainDoggles?

[CaptainDoggles]

Originally Posted by Robo.

Of course they did, but did they really strain a brand new engine to verify the max speed on the deck? If you have any further information about the tests conducted by RLM / BAL in order to accept an airframe they have paid for? That would be great to know, but using logic again, would their test pilots push the new a/c to its limits? I believe they would not and if the plane performed within limits, they were happy.

It's not "straining" the engine if that's what the engine has been designed to do. The engineers say "you can run at XYZ power settings for 5 minutes." Why would the RLM pay for aircraft they aren't sure can meet the contracted obligations? They must have verified that the aircraft can deliver. It's a simple fact, and continuing to cover your ears and sing LA LA LA LA in face of this fact makes me think you are just another forum troll.

No, I never said such thing. I never stated that Mtt failed to deliver what they were legaly bound to. I said they most probably did not perform extensive tests to prove our point. The fact is, no matter what test you look at, no aiframe ever managed to reach the speed in the Mtt chart. That brings you straight back to the beginning of this discussion.

Either they tested enough to ensure the required performance was being achieved or they did not; there is no middle ground. Either the aircraft met the requirements or it didn't. There is no middle ground. You can't say "I'm not saying they didn't deliver what they were required to deliver" in one breath and then say "they didn't do extensive testing" the very next. HOW DID THEY KNOW WHAT THEY WERE DELIVERING IF THEY DIDN'T VERIFY IT WITH TESTING?

And again you're trying to make it sound as if every single test ever conducted on the 109E shows it not meeting proper speeds. Guess what? We don't have the data from every test ever. Stop trying to re-frame the issue based on your agenda.

----

I'm done engaging with you on this subject. You next post is going to be another one saying that the contractual obligations were actually just imaginary, theoretical numbers and blah blah. I don't have the patience to repeat the same facts over and over and have somebody just ignore it and say "but I think it's this way" so I will leave you to it.

[Robo.]

Originally Posted by CaptainDoggles

It's not "straining" the engine if that's what the engine has been designed to do. The engineers say "you can run at XYZ power settings for 5 minutes." Why would the RLM pay for aircraft they aren't sure can meet the contracted obligations? They must have verified that the aircraft can deliver. It's a simple fact, and continuing to cover your ears and sing LA LA LA LA in face of this fact makes me think you are just another forum troll.

No, I am not another forum troll, just because I don't happen to have the same opinion like you. Please keep this unpersonal.

I am asking a simple question(s): Did they try to fly the airplane at full power at the deck as a part of the test? Did they verify the performance by attempting to achieve the top speed at any other altitude? They obviously did - and seeing the aircraft producing MFP / RPM expected, they simply assumed the curve as such was met within limits. We don't know, unfortunately, what ata they have been using. Other inspections (instruments, equipment etc.) were more important and if they were happy, they did not send the a/c back to get any issue fixed.

How do you think the Emils in CoD should be modelled?

Originally Posted by CaptainDoggles

And again you're trying to make it sound as if every single test ever conducted on the 109E shows it not meeting proper speeds.

No, I am not. Please read my posts again if you care. I am just asking what the 'proper' speed should be.

Originally Posted by CaptainDoggles

I'm done engaging with you on this subject. You next post is going to be another one saying that the contractual obligations were actually just imaginary, theoretical numbers and blah blah. I don't have the patience to repeat the same facts over and over and have somebody just ignore it and say "but I think it's this way" so I will leave you to it.

That's OK with me dude. I am not saying any of the above, I simply don't see it as black and white as you. No need to get emotionally involved , if you can't answer my questions by providing some facts, that's fine. I respect your opinion and I don't ignore it at all, but I keep mine until I get enough facts to adjust it. We are not about change anything anyway so please take it easy.