SPIT MK I/II and over boost

[ACE-OF-ACES]

Originally Posted by IvanK

Neat On line implementation of Il2 Compare whose responsible for that ? V101_Tom or Ace of Aces ? ... be nice to see the fan plots in there as well.

This I..

See the link to the pdf in my previous post.. I have fan plots (aka DogHouse) and Ps charts and more.. I am slowly adding those each weekend that I get some time to work on it.. I actully have the fan plots done, but, I need to add the lables for the constant load factors and constant turn radius lines..

I have done all this before in MATLAB, but never before in a website app in C#, but it is not hard to do, just takes time. My goal is to have everthing that is in that pdf on my webpage.. AND MORE! For example, you can change the fuel loads in my version of IL-2Compare Online, which is something you could not do in the old executable version

[ACE-OF-ACES]

Originally Posted by ACE-OF-ACES

In that it is something I am well aware of, and none of the standard WWII performance charts like TAS vs Altitude and ROC vs Altitude are depended on the E state. As a mater of fact the test methods are preformed such that E does not factor into the test.

Hmmm before someone jumps me on this.. Allow me to say this better than I said here

Originally Posted by ACE-OF-ACES

In that it is something I am well aware of, and none of the standard WWII performance charts like TAS vs Altitude and ROC vs Altitude are depended on the conversion of E. As a mater of fact the test methods are preformed such that conversion of E (i.e. alt to speed, or speed to alt) is not allowed. That is during a speed test altitude is held constant, thus the change in E is only due to the change in speed. Where as during a ROC test, the speed (climb speed) is held constant, thus the change in E is only due to the change in altitude

There that is more correct

[JtD]

Historical performance data for climb typically comes with a climb speed information. This climb speed hardly ever is constant. Often, TAS increases while IAS decreases. This has an effect on climb performance, and it is measurable. Il-2 compare does not take the planes acceleration into account, and the climb performance in Il-2 compare is a little bit higher than what is achievable in game or would be, even if perfectly modelled, with the real plane.

[klem]

Originally Posted by SEE

"Even a child could fly one!" no guesses who made that famous remark!

The simple truth is that many of the pilots who flew these highly advanced machines were just kids fresh out of school with no combat experience.

That remark is testament to Mitchells excellent design - a damned good fighter that a kid and young men could, and bloody well had to, fly against overwhelming odds, excellent Axis fighters and adversaries with more combat experience!

One question asked at the time was "could the average RAF pilot go to war in this". Answer, born out by the many interviews you can still find on Discovery, History, etc channels is "Yes" and "you didn't get into a Spitfire you strapped it on, it was a delight to fly" (Bob Doe I believe). Adolph Galland, comparing it to the Me109: "The Spitfire was ridiculously easy to land".

On the subject of 'E' state, performance, is it right? etc.. A decent flight model will take all that into account. The data for power, weight, drag factors etc have to be correct and the environment data, including gravity, is modelled in.

In simplistic terms 'E' at 500 feet is essentially the same as 'E' at 10,000 feet for the same true speed. E=MC^2. Its when you change altitude, power etc that E changes. Potential E is another matter, you have the potential to develop much more E at 10,000 feet (by diving) than you do at 500 feet, also you have the potential to develop more E by putting up the power.

[TomcatViP]

It seems I need to add some clarification here.

The Term I invented - E-Liability - was part of attempt to make a joke combining the Law of Energy conservation (Em=cte - Em being the mechanical energy of a closed system - ie : every well defined system) and the fact that our beloved Spit in IL2 had the right to bypass it (the dive climb maneuver for example).

SO sorry it was pure un-intentional trolling

Specific excess power (SPow) is what come close to this - Thx IK.

Just remind that Em = cte is not a true representation of what is really happening. The plane is in fact trading energy with the surrounding air at an huge rate so the the neat amount would be most of the time negative in a dogfight.

For example, flying level if you attempt a climb you'll go higher than if you had started turning just before. An other example is the yoyo move.

A good equation IMHO that give a clear picture of this is the low kinetic energy that stat that the time derivation of the kinetic energy equate the sum of consumed power of a system

dEc/dt = Sum of (P)

With P being the power of the engine, the power consumed by the drag etc... depending only of the speed and the turn rate.


BoT :

Following IK remark : 0.6G is a huge diff.
But doesn't it look right if you compare the wing area ?
However it would be only an advantage in a flat turn. Slow speed turn with vertical added would be problematic for the Spit pilot giving the wing being prone to dyn stall (lower aspect ratio + thiner + elliptical planform) and the ctrl sensitivity in pitch that you alrdy hve demonstrated.

But do we hve similar curves for the Hurri ?

[SEE]

The technical theory FM arguments are way over my head but I appreciate everyones input. I just read Cambers post (excellent too!) and it refers to the Acusim modelling of the Spit.

I asked someone who has this installed how the Spit compared to the one in CloD regards handling? His opinion was that it was very similar (better in some aspects regards performance).

I appreciate that it has little significance in contributing to this discussion but I would be interested to know if there is a marked difference between the FM modelling given to us by MG and another such as Acusim both of whom I would imagine are researching and using the same data.

[ACE-OF-ACES]

Originally Posted by JtD

Historical performance data for climb typically comes with a climb speed information.

Typically? Well I have not counted all the test reports that included BCS vs. those that did not include BCS, but based on my memory I have seen more test reports without BCS than with

Originally Posted by JtD

This climb speed hardly ever is constant.

Same is true wrt altitude in top speed testing.. It is impossible to maintain a 'constant' altitude.. But the NAVY test documents say the altitude must be held within a 'range'.. If I remember correctly it was something like +/-100ft or 150ft. Same goes for BCS.. It is impossible for a human to maintain a constant BCS. The goal of each is to keep both as constant as humanly possible during the test from one second to the next. Some if not most planes ROC performance required the BCS to be adjusted as altitude increased, but the change was done such that the transition was smooth and within that +/- acceptable range such that the IAS could still be considered constant from one second to the next.

Originally Posted by JtD

Often, TAS increases while IAS decreases. This has an effect on climb performance, and it is measurable.

Often? Actually TAS 'always' increases with altitude.. But in WWII TAS gauges were the exception to the rule, that is to say most if not all fighters only had IAS gauges. Thus the test pilot focus was on the IAS, but not because he didn't have a TAS gauge as much as the stall speed is realities to IAS, not TAS. Thus they would keep the IAS as 'constant' during the ROC test from one second to the next, While TAS increased during the test due to the increase in altitude.

Originally Posted by JtD

Il-2 compare does not take the planes acceleration into account,

That is good news wrt ROC testing because as in real life the goal was to keep the BCS as constant as humanly possible. And as any high school physics book will tell you, when velocity is constant acceleration is ZERO. So another way of putting it, you could say that during a ROC test the goal is to keep acceleration as close to ZERO as humanly possible, even during the transitions in BCS

Originally Posted by JtD

and the climb performance in Il-2 compare is a little bit higher than what is achievable in game or would be, even if perfectly modelled, with the real plane.

Maybe.. I guess it really depends on ones definition of 'a little bit' but based on the +/-5% acceptance the IL-2Compare data falls well within (matches) the manually flown (3rd party test pilot) test results that I have done.

[ACE-OF-ACES]

Originally Posted by TomcatViP

and the fact that our beloved Spit in IL2 had the right to bypass it (the dive climb maneuver for example).

Fact?

Really? Well than there must be some well defined and documented test of the ingame spit to make such a claim.. Right?

Can you provide us the link?

I think that would be interesting to see just how that test was conducted.

On that note, here is a classical WWII ZOOM test I did back in 2007 on the Spit 25lbs

Spitfire MkIX 25lbs

And I saw nothing in that test that would suggest it was ignoring the laws of physics..

Also, when I did the FM ANALYSIS of the Spitfires, I saw nothing in the Ps charts or Doghouse charts that would suggest it was ignoring the laws of physics

But maybe this test your referring to does?

So I am looking forward to the reading the test that your FACT claim is based on!

Thanks in advance!

[CaptainDoggles]

Originally Posted by ACE-OF-ACES

Often? Actually TAS 'always' increases with altitude..

Not during zoom climbs.

[JtD]

Neither his point nor mine.

Regarding acceleration in a climb, that's TAS you need to look at, the energy of a plane going 600 in vacuum and going 600 in sea level atmosphere is the same, even if IAS in one case is 0 and in the other 600. That energy needs to be accounted for. Flying the plane a a constant IAS will not give you an acceleration free climb.

As an example, the acceleration during a climb at a constant IAS of 360 km/h to 6000m in standard atmosphere will cost you about 400m in altitude, or 7% in average climb rate. At lower speeds, closer to the typical climbing speeds of WW2 aircraft, the loss is less, around 3-4%.