Spit/109 sea level speed comparisons in 1.08 beta patch

[Jam66es]

I sense that Red pilots not knowing/ignoring this limitation may be at the culprit.

[Robo.]

Originally Posted by Crumpp

Spitfire III, AFAIK only the prototype was built.

Yes, I know, only few built. My point was that the original data linked by Banks were of Merlin III powered Spitfire.

Even your image is not an Mk.III, just the 1st page.

[Robo.]

Originally Posted by Crumpp

Do you know where cruise speeds are located on the Power and thrust curves?

Need me to show you.....????

No need, thank you.

All I said was that you were wrong in your statement that 400kph fixed trim setting was due to the 'good speed for dogfight' reason

http://forum.1cpublishing.eu/showpos...&postcount=323

Originally Posted by Crumpp

When you calculate out the performance, it is easy to see why Mtt defaulted the trim to 400kph.

That is a very good speed to dogfight the airplane.

It is a very good speed to dogfight the airplane, but that has nothing to do with the sustained turn debate (in practical reality of an actual air combat). I explained that earlier. It is also not the reason for default trim settings, that reason was actually cruise speed at 1.15ata @ 2200U/min.

Here again:

Originally Posted by Crumpp

Why do you think the trim on the Bf-109 is set to 400 kph IAS???
You do understand they can trim the aircraft for whatever speed they desired?? Having a fixed trim condition is a great way to set the combat speed for your airforce.

Please don't mix up facts as they suit you to prove your bizzare theories.

[Osprey]

Originally Posted by Crumpp

Spitfire III, AFAIK only the prototype was built.

That was built for the Griffon engine but they had a ton of problems and dropped it. The Merlin XX wasn't used in the Spitfire, that's why Robo is rightly taking the mick out of you.

[NZtyphoon]

Originally Posted by Osprey

That was built for the Griffon engine but they had a ton of problems and dropped it. The Merlin XX wasn't used in the Spitfire, that's why Robo is rightly taking the mick out of you.

In this case Crumpp is right, just for once - the Spitfire III prototype was built with the Merlin XX, which had a single-stage two speed supercharger - it also had clipped wings, a revised undercarriage which was raked forward by 2 inches, and a revised windscreen with two straight side pieces and flat windscreen with internal glass (the undercarriage and windscreen were later used on the Spitfire VC) . When it was decided to reserve the XX for Hurricane IIs the Mk III was adapted to take the first Merlin 60 series engine, becoming a Mk IX prototype. The Mk IV was very similar to the Mk III but had the Griffon engine.

[Osprey]

OK so I may be a version out here lol Either way it's another case of running with it because there's a war on, not exactly the engineers style planning he expects in theory. Of course it's theory that engineers plan because where I work, which is a very successful global engineering firm, the engineers have virtually zero planning, all prototyping and wing their projects (plastering it with documentation on the fly). It's in software, my dept, which has far more planning than the engineers.

[Robo.]

Originally Posted by NZtyphoon

In this case Crumpp is right, just for once - the Spitfire III prototype was built with the Merlin XX, which had a single-stage two speed supercharger - it also had clipped wings, a revised undercarriage which was raked forward by 2 inches, and a revised windscreen with two straight side pieces and flat windscreen with internal glass (the undercarriage and windscreen were later used on the Spitfire VC) . When it was decided to reserve the XX for Hurricane IIs the Mk III was adapted to take the first Merlin 60 series engine, becoming a Mk IX prototype. The Mk IV was very similar to the Mk III but had the Griffon engine.

Very true, thanks for the details NZtyphoon. The key is the different (clipped) wings and therefore different wing load than the one we see at the top right corner of the above sheet.

Crumpp came up with the Merlin XX theory only to prove that the fan plot posted was for different engine with 2 stage supercharger. That is wrong just as was wrong his assumption that the chart posted previously by Banks (post 345) already included RAM effect.

No matter how I look at it, the post 345 makes perfect sense.

[Crumpp]

All I said was that you were wrong in your statement that 400kph fixed trim setting was due to the 'good speed for dogfight' reason

Again, robo...

I asked you if you know how to determine the cruise speeds for an airplane. These are not random figures, pulled from a hat.

They are specific points on the power required and thrust required curves. The cruise speeds points of the thrust required and power required curves are fixed by the design and completely independent of engine settings.

Do you need me to talk you through how to determine them?

It is very easy to proved I am not wrong if you understand how the physics works.

[Robo.]

Originally Posted by Crumpp

Again, robo...

I asked you if you know how to determine the cruise speeds for an airplane. These are not random figures, pulled from a hat.

They are specific points on the power required and thrust required curves. The cruise speeds points of the thrust required and power required curves are fixed by the design and completely independent of engine settings.

Do you need me to talk you through how to determine them?

It is very easy to proved I am not wrong if you understand how the physics works.

No, thank you, that is not necessary at all. I already know you're completely wrong with your 'combat speed default trim setting' statement, no matter how hard you now try to prove that you were actually right.

As for the actual question (sorry I thought it was a rhetorical one) I don't know how exactly to calculate cruise speed for an aircraft, and I don't need it in order to see that you wrote 'combat speed' instead of 'cruise speed'. Now you will probably reply with another graph to prove that it's the same thing. Maybe you're even right, but essentially, you wrote nonsense, hence my reply. Consider my knowledge as limited if you wish, but then if I even can see that you're wrong and that you're bending facts to fit your bizarre theories (maintain rpm by changing it constantly, RAM effect, Merlin XX etc...), that says something about your activity here, not mine.

I am not too sure anymore about what are you trying to achieve on this game's forums, perhaps you enjoy the arguing for the sake of arguing, perhaps you enjoy the advantage you think you're having with your theoretical knowledge. I actually enjoy some of your technical posts and I have no problem to understand what you were saying, but when you're wrong you're wrong. And for some reason you never admit it, you just go on and on and every thread ends up to be about Crumpp vs. the 'sane world' rather than about the original topic. I fond that a bit frustrating to be honest.

Let me ask you a question you also omitted before - how exactly would a 400kph sustained turn in a Bf 109E be useful in actual turnfight vs. a Spitfire Mk.I?

[Crumpp]

I already know you're completely wrong with your 'combat speed default trim setting' statement

In otherwords, forget any facts....

You are going to stick to your immature and emotional reaction.


Well, let's see how it pans out.

You can look in the Bf-109E3 Flugzeug Handbuch and see that the engine out instructions call for the pilot to pitch for 200kph IAS. This is best glide speed and corresponds to L/Dmax.

If our curves are correct, this will be the botton of the thrust required curve and tangent of the power required curve.

First the Thrust and Power Required curves:



200kph = 124mph +10 mph PEC = 134mph CAS * .869 = 117KCAS = 117KEAS at sea level.

Yep, best glide aligns perfectly with our curves so we know the curves are correct.

Using the curves, it is easy to find the other cruise speeds.

Maximum endurance will be at the point of minimum power required. Carson's speed is a modern innovation and is the best balance of fuel consumption and speed.

The trim speed of 400kph IAS does not align with any cruise point on the curves. That means the speed was chosen for a different reason.

Now it we look at the rate of turn, or how fast an airplane can bring the guns on target, we see that 206KEAS is a point the Bf-109E3 maintains a healthy rate of turn advantage and can sustain better maneuvering performance.



So, if it was not intentional, it certainly was a very fortunate turn of fate that the Germans choose 400kph to set the trim for the Bf-109E3.