Bungay didn't do the graphs as anyone who can read can easily see.

"Turning circles are calculated by John Ackroyd of Manchester School of Engineering."

Care to explain them.......

:-P

Sooooo, he's very intelligent and well respected....but since he is not an aircraft performance engineer or an aerodynamicist he therefore publishes incorrect information? Please clarify.

:rolleyes:

The altitude for the graph is at 0.0ft. The sources for them is stated at the bottom of the page.

Unfortunately there are very few aviation or aviation related books that meet Crumpp's extremely high standards, because they are not written by engineers. Until true professionals like Crumpp descend from their elevated heights and start researching, writing and publishing books on aircraft, our bookshelves will continue to be cluttered with books written by intelligent, well respected amateurs who know nothing and write abysmal nonsense.

So the entire left column showing altitude does not exist or is a typo or are you saying the turn performance is in EAS??

Maybe some experts will be along to tell us how wrong it is to use EAS??

LMAO!!!!!

:grin::grin::grin:

Thanks Milo, you are so predictable in your zeal to prove me wrong!

;)

My interpretation of the graph is that that bot the left and bottom figures are radius (note how the lines intersect exactly the same figures on both) and the note on the left just means 'sea level', no EAS or IAS involved, admittedly it is a very badly designed illustration.......what's the big deal?

I just googled EAS. So are you referring to the sports nutrition product, Energy Action Scotland, Employment Agency Standards, the European Athletes Society, European Astronomical Society, or are you just throwing in an acronym for the sake of it? :)

The graph in the book is a simple demonstration of relative turning circles. It's not scientific. It's very 'layperson', but not necessarily 'wrong' per se.

I'd say the altitude is a typo. The x and y axes obviously show the same parameter, i.e. radius of turning circle in feet. But I have the book, so I'll check if it's clarified in the text.

EAS is equivalent air speed, Crumpp will be along in a minute to teach you all about it....

Ah, thanks Bongo. I did guess that really. Bit of facetiousness I'm afraid. :)

However, I checked the text and there is no clarification as to the methods of calculation re the turning circle. It's a simple example for the readers of a book who don't have PhDs in aerodynamics. Or even a GCSE come to that.

But this doesn't make it 'wrong' per se.

:?


It does just mean sea level.

You would have to understand that True Airspeed at Sea level equals EAS.....

:rolleyes:

I see your comprehension is as good as it ever was.:rolleyes:

And you were wrong as Bungay didn't do the graphs.:) I don't have to prove you wrong as you do that very well all by yourself.

But do continue making a Olympus Mons out of a mole hill if it helps your ego.

I know...

Why do you assume I don't know that? I am merely trying to clear up some confusion on what the figures on the left side of the graph mean...some people seemed confused by it's meaning....:rolleyes:



your zeal is eqally as predictable.

It is scientific and all my calculations agree with the results. Unfortunately, radius of turn is not the best indicator of actual turn performance.

Because your statement is contrary and wrong.

http://forum.1cpublishing.eu/showpos...&postcount=107

It is cut and dry and requires no interpretation. You are just plain wrong.

That is why anyone would assume you don't know that True Airspeed equals Equivilent Airspeed at sea level. If you did know, then you are just lying about it in your above reply.

The performance is radius of turn in EAS.

I will let you guys mull over it and post some calculations with graphs. Not to define any specific performance but to see how the relative performance of these airplanes makes them very equal dogfighters.

We can look at the whole picture and examine various performance improvements in each design along with their effect on the combat performance.

We can see how the relative performance in the game stands up.

No my statement is 100% correct, the graph is turn radius at sea level, would you care to show me exactly where any reference to speeds are made on that graph.

Now kindly remove claims of me being a liar and other accusations....thanks :rolleyes:

Actually the graphs were done by an engineer..

Which is something I pointed out in the first response to this graph where I took the time to read and than quoted the graph's source, i.e.

Thus proving that humans (pilots, engineers, etc) can make mistakes..

As for the graph, as I initially noted, I questioned it's purpose..

Initially it seemed like it was done to give the impression that the 109 turn circles are far worse than the Spit and Hurri..

Which they well may be!

But, if that is the case this graph does not do a very good job of showing it!

It actually raises more questions and cast doubt for those who are use to looking at performance graphs (like myself)

If the purpose was to convey the turn radius (circle) at sea level than there is no need to provide an X (radius) vs. Y (alt) graph in that there is no X (radius) vs. Y (alt) taking place..

It is just X (radius) @ Y (alt)

IF that is the case, than placing 'Altitude (000ft) along the Y axis was wrong!

A better way to 'graph' this 'data' would have been to draw circles inside of circle with the radius associated with each circle and title the plot turn radius (circle) at sea level

like this one...

http://www.wwiiaircraftperformance.org/wade-turning.jpg

Bingo!

Now looking at this graph..

We can see that the P51 and Spitfire both have a tighter turning circle (smaller radius) because their circles are inside the outer circle that

Also note, the outer circle (bigger radius) contains the the Bf109 along with the Tempest, Fw190, P47

The only info left off here is what is the speed and altitude?

Because these relationships can change with altitude

Also we can safely assume that this are the best turn circles at the best turn rates, but what is the rate?

Which is important, because what you really care about is the time it takes to do a say a 180 (reverse direction).

There is no doubt that there is some sort of demonstrating our superiority ooze about these turn radii graphs... but regardless the figures seem to be about right.

It is entirely another question why this so called superiority is given so much importance. Even the graph shows that the turn radii difference between the Hurri and the 109 was about 200 feet, or about 60 meters. Even the span of these aircraft was 11-12 meters, and actually that's about the distance a 109 wingman kept from his leader... or even less. So what's all the fuss about it?

BTW the figures are rather similiar to what Morgan and Morris came up with in 1940 (for 12k feet - both figures are more of an educated estimate, not trials): http://kurfurst.org/Tactical_trials/...ls/Morgan.html

http://kurfurst.org/Tactical_trials/...s/image019.jpg

Your statement the graph is at sea level is correct and not the issue.

The issue is you imply that speed is not part of the equation and therefore it is wrong to say it is Equivilent Airspeed.

You do know we cannot have rotational motion without velocity, right?

An airplane that is not in motion has no turn radius.

It is not the fact the performance is graphed at sea level.

In fact, that is WHY it is Equivilent Airspeed!

It is the claim that you knew what EAS is used for and do not recognize that is questionable.

Does that mean EAS is just a term that you heard someplace or do you know its uses? It is ok to admit you don't know everything. I certainly don't, just ask my wife! :-P

I did not call you a liar at all either. I said either you did not know or you are lying. You claimed to know about Equivilent Airspeed in your second reply but you made the statement EAS or IAS is not a part of the math used to derive the graph published in the book. It is probably NOT done in IAS. While it is valid to do a turn performance analysis in IAS, it is not valid for performance comparision because of the PEC. It is also valid to do it in Calibrated Airspeed but CAS = EAS = TAS at sea level.

The fact is your only point is get the conversation shut down at this point so that we do not get to see any analysis that might not fit a small and very vocal agenda. Don't do that. What will follow is unbiased math that anyone can reproduce given the knowledge of aerodynamics. I will even keep it to the college algebra level so it is easy to see.

I am hoping it will quiet down the critism of developers on their FM's. I think they are close in the big picture and the Spitfire's issue is the heat effects. We can prove that.

Bottom line, I did not call you a liar. I said you made the claim to know something and either you did not fully understand it or not forthcoming about the level of understanding you posses. I have no idea what you do or do not know outside of what you write on these forums. The impetus is on you.

merely a case of you making the wrong assumption, I made no reference to equations or any such thing, you were obviously a little over eager to jump all over a grammatical error, I should really have said 'no EAS or IAS refered to'......there.....does that help your blood pressure any?

Not really, I provided all the evidence of my qualification...what do you need? a picture of me holding a 'hello Crumpp' sign while actually flying an aircraft?....:rolleyes:

lol

Really?....the graphs were sourced from litterature as far as I can see, nobody on this forum produced them in any attempt to ooze superiority, and you can still say that despite providing your own source which verifies the accuracy?.......

only because it is further evidence to the argument the Spitfire was a more agile aircraft with better turn performance.....whats all the fuss about?

;)

That is a good point

Initially I got the impression that is what the graph was trying to do..

But based on the table that Kurfurst just posted, I see now the graph is right, just it's presentation was not all that it could be.

Put another way

As the graph implied.. (at sea level)

And Kurfurst table confirmed.. (at 12kft)

The Spit does turn a lot better than the Bf109

At more than one altitude!

Turn radius is for turns at sea level. Estimated best sustained turn. Corresponding turn times from same calculation:
Hurricane I: 17.6s
Spitfire I: 18.2s
Bf 109E-3: 20.5s
Bf 110C-4: 20.5s (was also calculated, with radius of 840ft)

While absolutely correct for relative performance, just examining a single point of best performance does not give one the best picture of the relative dogfighting capability.

Looking at one single point in the envelope tells us the Bf-109E3 is hopelessly outclassed IF it tries to match the Spitfire at the Spitfires best performance velocity.

Fortunately, all airplanes have their own unique best performance speeds and the Bf-109E3 is no different.

Here we can see the entire sustainable load factor envelope for both aircraft.

http://imageshack.us/a/img802/1949/s...bf109e3sus.jpg

What is shows us is that in order for the Spitfire to realize it's turn performance advantage, it must go slower than the Bf-109E3 by some 30Kph or 18 mph.

That means the Bf-109E3 gains the initiative in the fight if the Spitfire tries to use its sustained turn advantage.

Once more, the Bf-109E3 pilot can take his aircraft all the way to its best sustained turn performance point without fear of losing the initiative.

Factor in the stability characteristics and these airplanes are very evenly matched in close quarters dogfighting.

That means the Bf-109E3 gains the initiative in the fight if the Spitfire tries to use its sustained turn advantage.

Can you reword this so it does not come accross as a bizarre contradiction?

It is not a bizarre contradiction in aerodynamics. ;)

It is a general trend in aircraft performance. You have stumbled across the reason why designers concentrated on high speed instead of low speed performance.

Ah yes, he seems to be slightly confusing again. What I think he's trying to say is that a 109 turns better than a Spitfire at higher speeds - which is no news and pretty obvious, but it also has nothing to do with sustained turn times comparsions.

I'd like to see a Hurricane in the game that has better sustained turn than a Spitfire AND a 109. What we have got now is:

1 Spitfire
2 109
3 Hurricane

Let me add in game speed, climb and dive to that Robo :D

1. 109
2. Spitfire
3. Hurricane

1. 109
2. Spitfire
3. Hurricane

1. 109
2. Spitfire
3. Hurricane

.....still willing to take the Hun on :)

Allow me to ask again, what I'm reading in that odd sentance is;
The spitfire has an advantage, unless it tries to use it.

it roughly translates in Crumpp parlance to:

The Spitfire has an advantage until it is matched against anything German and I produce the graph to prove it'

takes a little time to learn Crumpp but it becomes reasonably predictable.

No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity. According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.

Great summary. :) I guess that's the way he put it, but it boils down to the statement that the faster plane generally holds the advantage. This remains true in turnfights. The 109 has the choice to maintain the higher airspeed at a lower corner velocity, the Spitfire has the choice to maintain a higher corner velocity at a lower airspeed, so the 109 can maintain the initiative.

It should be noted that on Crumpps chart the 109 has a level speed advantage of ~18 knots, however representative that is for a BoB scenario.

Feel free to calculate it yourselves!!

The performance is the sustained envelope. It is just over the entire envelope both aircraft can sustain instead of just choosing one single point.


So it is everything to do with sustained turn time comparisions as it IS A SUSTAINED TURN TIME COMPARISION under the same condition of flight. At the same altitude and airspeed, that is how the relative performance will play out.


You do understand the Spitfire and BF-109 do not achieve their best turn performance under the same conditions of flight?

It was manufacturer's data for each type.

There is a wide range of data available on both types. Choose what you want.....

Do the math...it does not lie.

Spitfire data used

http://www.spitfireperformance.com/n3171.html

Bf-109E3 data used:

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

An obvious statement but the Spit trials you quote above seems to be without the extra boost that 100 octane allows.

A second observation, can someone explain how the Me109 is supposed to have a better manoverability at higher speeds than the SPitfire when all the tests point out how difficult the 109 is to manoever at high speeds due to the way the controls stiffen up at high speed compared to the Spitfire?

Last I don't see how the chart on posting 129 page 13 proves what it says it proves. I would appreciate it if it could be explained to me in simple terms or explain the maths behind the criteria thanks

Yes that pretty much nails it.

The speed advantage is still speed advantage as JtD said it 100% ly - ''This remains true in turnfights. The 109 has the choice to maintain the higher airspeed at a lower corner velocity, the Spitfire has the choice to maintain a higher corner velocity at a lower airspeed, so the 109 can maintain the initiative.''

Yes that's what I was saying before. ;) But when it comes to sustained turn that does not really matter.

Do you know what would happen if you entered a pure turn and burn (TnB) fight against a Spitfire (you in a 109)? :-P

It does not change the outcome or outlook. Despite the higher wingloading, the Bf-109 has more excess thrust because it is lighter.

How is your statement ANY different from mine???? :confused:

Performance in the context of the conversation is TURN performance.

The Spitfire has to reduce speed significantly below the Bf-109's to reach that best turn velocity.

That is a fact.

That is one way of looking at it.

Another way is the Spitfire must give up 30 kph of speed in order to realize any advantage at all.

It is the same exact scenario. One that leaves the Spitfire with no choice but hope it sticks around in the turn fight.

If the Bf-109 does not, the Spitfire has lost the initiative.

Sure, you would use the Bf-109's sustainable load factor advantage to put the Spitfire turning defensive circles beneath you until you killed him.

Don't confuse high load factors found in instantaneous performance with low load factors achievable in sustained performance.

That's not the TnB mate. ;)

yea i thought that was ZnB?

You're saying the 109 is flying at the Spitfires best turn performance speed, I am saying the 109 is flying at its own best turn performance speed. Quite a difference.

No I am not. I am saying both aircraft are flying best turn performance.

Best turn performance is a specific speed.

In the single point analysis of best turn performance, the airplanes are at different speeds.

When we look at the entire envelope, the Spitfire must be at a slower speed in order to outturn the Bf-109.

http://imageshack.us/a/img228/1949/s...bf109e3sus.jpg

That graph must be rubbish.

I don't pretend to understand what it's supposed to mean, but the aircraft leave the graph in opposite directions. That just doesn't happen in graphs of real world effects.

First thanks for the replies

My first observation was that the Spit test you used didn't include the extra power from the 100 octane fuel

I say it does make a difference as the extra boost came with a significant increase in power which significantly improves the power weight ratio. Also lighter is a factor but a bigger one is drag which is where the 109 loses out.

Re your second reply
You have a point but nowhere have I seen anything that says that the 109 had a better sustained performance. Also what is sustained? Everyone seems to agree that the SPit turned tighter and faster so what is sustained. Are you trying to say that after X turns the 109 would start catching up because it has a better sustained performance?
My understanding is that a sustained turn rate is one that can be maintained for long periods of time without losing altitude, maximising the turn rate and radius of turn.
On both these counts the Spit will beat the Me109 as proven in the Rae tests which were sustained turns without losing height

Re the Graph,s I still don't understand what you are trying to prove. Lift limit is a new term to me but I assume it has something to do with the max lift the wing will generate given a certain angle of bank, but how load factor impacts this I don't have a clue, as the load doesn't impact lift. Load factor increases with bank which will increase the amount of lift required but lift available in the wing is a constant
Thrust Limit is also a new term to me I assume its a power to weight thing, but again don't understand how load would impact it as thrust is a given depending on height etc but not as far as I am aware load factor. The thrust required is increased as the bank increases but in a given aircraft it is a fixed amount.

What power and speed? I will recalculate and repost.

If you understand stability and control engineering, Mtt did a good job on the Bf-109.

It is the performance the engine can perform until it runs out of gas.

Yes

The RAE test's were of turning ability. If you look at the test the RAE flew the airplanes at ~115KEAS in their evaluation.

Lift limit is the aerodynamic limits of the wing. Propeller aircraft are called power producers and are aerodynamically limited at the stall point.

The lift line is the stall line.

Load does impact lift.....

It is the thrust limited portion of our envelope. Here the aerodynamics of the wing are not the limiting factor but rather how much excess thrust the aircraft can produce.

Actually drag is the factor where the 109 may win out at high speeds. Parasitic drag is much lower on the 109 than on the Spitfire, and parasitic drag is what dominates total drag at higher speeds. The Spitfire turns better at low speeds because it has lower induced drag, and induced drag is what dominates total drag at low speeds.

Sustained turn is just the maximum g-load at which drag = thrust. Maximum sustained turn (i.e. the number usually quoted for turn times) is always achieved at lower speeds, but that doesn't mean the trends continue to high speeds and may be reversed. I am not sure if there is much to it - it can be well true that both aircraft can only turn so slowly in a sustained fashion that there is no tactical point in it.

Bottom line, a faster aircraft will always outturn a slower aircraft at high speeds, the question is not really wheter this happens or not, but: by how much?

Bingo!

Not sure you understand much of the science at all. I certainly don't like the attitude or implication I have something to prove or a vested interest in the outcome.

The math is what it is.....

So to sum up you do not disagree that the Spit had a better sustained turning ability, your position is that the 109 had a better sustained straight line performance because the engine had a better sustained performance.

Just trying to get things straight in my mind before going any further

I think you will find that load increases the lift required in a certain situation and if I remember correctly roughly doubles at 60 degree bank

I don't know the numbers for the parasitic drag for these aircraft but would expect the difference to be marginal. The Spitfire is a larger aircraft and this would count against it but the 109E has less curves and is less aerodynamic which would balance it out. Indeed the 109F was more streamlined and this contributed to its improved performance. Which has the advantage I don't know but I would expect it to be close.

I believe your bottom line re a faster aircraft always outturning a slower one to be wrong. If it were right the 262 would out turn everything

I don't know if your trying to prove that the 109 had a better sustained turn or straight line speed and don't see how the diagram helps either case.

In short I don't see how it proves anything.

Inspired by another post here about possible speed gauge error I made a little test.

I created a mission in FMB, where I let 2 AI planes fly next to each other for some miles. One was a 109E-4 and the other a Spit 1 and they were programmed to go at 300 kph at 500 meters.
I measured the time it took for them to travel 20 km and I checked their speed gaugets (AI on).

Observation 1: The 109E-4 outran the Spit on every try No idea why they did not match speed since I used exactly the same settings on them. :grin:

Observation 2:
The airspeed gauge on the 109 red 310 kph, but the calculation gave me 325 kph=a difference of about 5%

The spits gauge showd 170 mph=273 kph, but the calculations gave me 316 kph=a difference of about 15%

I'm aware that I'm comparing IAS and ground speed here, but the difference at 500 meters should not be this big, right?

Compare theese results with Cambers table :grin:
Coincidence? :confused:

/m

Well, that is because you don't understand aircraft performance.

That is ok and you are not alone.

It proves exactly what I said and the math does not lie nor is it bias.

I will see if I can help you. If I can't, oh well, it does not change the physics or the math.

Angle of bank and load factor have a fixed relationship in a steady state turn.

For example, 60 degree of bank will always produce a 2g load factor no matter what the aircraft under consideration.

Turn rate and radius is a function of angle of bank and velocity.

All aircraft at the same angle of bank and velocity will make exactly the same turn. So if a Cessna Corvalis and a Boeing 747 are going 200 knots and banks 60 degrees, they will both make the same rate and radius of turn.

Radius is very velocity dependant.

From an FAA question when getting your commercial certificate.....

An aircraft holds a constant angle of bank and velocity increases. What is the effect on radius?

The correct answer is load factor remains constant and radius increases.

At the same velocity, the aircraft which can sustain the highest angle of bank is achieving the higher load factor and will make a smaller radius as well as higher rate of turn.


So that diagram shows the Spitfire cannot realize a sustained turn performance advantage until it reaches the portion of the envelope the Bf-109 cannot fly in anyway. Then the Bf-109 must reduce its angle of bank in order to match speed and the Spitfire can sustain a higher angle of bank in that portion of the envelope.

If a Spitfire enters a turn fight with a Bf-109, the Bf-109 can force the Spitfire into this low speed realm. The Bf-109 will simply outturn or match any Spitfire that tries to remain at the same speed or maintain velocity.

So both pilots have to make a choice. The Spitfire pilot can choose to hold onto his airspeed and be shot down. The Bf-109 pilot can choose to follow the Spitfire into the low speed realm and be shot down.

Factor in stability and control, these aircraft are even more equal dogfighters. The Bf-109 pilot can precisely attain and hold a target load factor to achive maximum performance.

The Spitfire requires a skilled pilot to precisely achieve and maintain a target load factor in order to achieve maximum performance.

Understand?

There is some debate on this issue.. But one thing that I am sure of (99%) is the guage values are.. well.. not great! ;) I have seen that they lag other values (see below), I think to simulate guage reaction times.. Also they have some strange offsets associated with them.. For example, the ROC reads around 65+ fpm while sitting still on the runway! ;) So for those reason and more I have been leaning towards using the 3D world relative values (Z) over the cockpit guage aka indicated (I) values. They are not without issues either.. I say issue but it just maybe something we are not told about them yet, maybe the soon to be released read me will clear some of that up? Anyway the Z values seem to be the way to go for now IMHO.

An aircraft at Vmax has zero excess power.

So, the slower airplane has zeo excess power at its top level speed while the faster still has excess power to maneuver.

Understand?

Have you sat in the cockpit of many real airplanes?

;)

Emm we have this chart from RAE

http://i40.photobucket.com/albums/e2...109susturn.jpg

It clearly shows that the Spitfire MK I has better sustained turn performance throughout the speed range than the Bf109E3. It also shows Max sustained G of the Spit as 3G whilst the max sustained G of the BF109E3 is about 2.3G. With the Spit I weighing 6000lbs and the 109E3 weighing 5600lb.

We then have this chart

http://imageshack.us/a/img228/1949/s...bf109e3sus.jpg

Which shows the BF109E3 having a better sustained turn performance than the Spifire MKI throughout the speed range. This chart shows (at Take off weight nonetheless) the Spitfire max sustained G of 3.2 g and the BF109E3 max sustained G of 3.25g

Whose chart do you believe RAE or this other thing ?

Well Ivan I would believe the chart made by a practicing aeronautical engineer over a theoretical aeronautical engineer.

math is math, and physics is physics.

But coding useful models is a different animal. Part of my job is coding physical process simulations. Providing you have implemented the correct maths, your output depends on the physical constants you choose as appropriate.

Perhaps if you listed the constant values you used for the Spit and 109 we could evaluate your graph a little better. The math equations would be good too.

camber

Very true, but this has nothing to do with a sustained turn time. Say you're attacking a Spitfire in a Fw 190. You're much faster, he breaks and at that speed difference (him slowish, you very fast), you can turn inside him for long enough to place a burst in front of him. You lose some speed, he loses a wing if you hit, but that's not a sustained turn competitiion. You would never ever even at this theoretical advantage at this particular speeds enter a turn and burn fight and remain in that turn because you would lose the fight.

Not to mention G-load and blackout. Or if you're in a 109 the elevator stiffness at high speed would be (and is) a massive issue, too. In a sustained turn entered from higher speed, you happen to slow down anyway and the best you can do as a pilot is keep your speed at optimum (not to slow down too much) and watch the G load because if you can't see you can't shoot. We're talking pure TnB fight where the sustained turn rate plays a huge role (and pilot's skill is another 50% because). Obviously, this rarely happens in RL (or virtual skies) because you don't want to burn all your Es in a sustained turn, especially so in a 109.

You would be surprised how many 109 pilots still enter TnB fight vs. Spitfires. And they will almost always lose because (surprise surprise) the Spit has got much better sustained turn.

In theory. I would really like to see how a Me 262 outturns a P-51 in a sustained turn even at very high speeds. :o

Yes this is true. For a graph of a hypothetical situation, but if it was actual dogfight, the Cessna would outturn the 747. I understand what you're saying though.

Diagram shows something that did not exist in real life and luckily it does not exist in the sim either. Spitfire can realize the turn performance advantage at almost any moment unless the speed difference is largely in favour of the 109 - at which point the 109 pilot won't try to enter a pure turning competition (and that's what we're talking here about) anyway.

First pilot to reduce the angle of bank is very likely to lose the (turn)fight. If the 109 pilot gains speed and climbs we haven't got pure turnfight anymore and we can't speak of sustained turn either. Of course, in real virtual dogfights this is exactly what happens and both pilots usually fly yo-yos and the turn is egg-shaped rather than a circle etc. There is much more to it in actual combat. Sustained horizontal turn rate is still very important when it comes to TnB and this is where Spitfire beats the 109. (still depending on the pilots of course).

I suggest you start flying these combat flight sims, while you're hangin around on the forums you might as well want to actually try what you're typing in here. It won't work I am telling you now :-P

This is as wrong as it can get mate :grin:

Any pilot can do that. Of course pilot skill plays a huge role in here, too. There are more tricks in how to outturn your opponent and win the edge. This is where the human factor comes in. But speaking strictly of the machines and the sustained turn potential, Spitfire would be the winner at typical TnB speeds. That's why any sane 109 pilot avoids TnB with a Spitfire.

Actually it's the other way around. Average Spitfire pilot will outturn any average 109 pilot hands down when it comes to sustained turn. It requires exceptional 109 pilot (esp. engine management and stall control, very clean rudder) to outturn a decent Spitfire pilot in a proper turnfight.

I understand that you have no experience with virtual dogfight. Your theoretical knoweledge is useful but you would die in combat if you tried to apply it. ;)

:grin: Yes it seems the Z value is the only reliable "gaguge" för speed. My point was that it seems like there is quite a big difference between the speed gauge in the spit and 109. Countless posts on this forum complain about the spit is going too slow in level flight and most of them draw this conclution from the speed gauge alone. I'm not saying they are wrong, but reading the speed gauge gives the impression that a 109 is travelling much faster than a spit, even if they are flying side by side.

Don't forget the inherent display bug on all RAF ASI's .... that is the needle drops rapidly in response to G. You can drive the RAF ASI any way you want with minor applications of G. So any time you are pulling G the RAF ASI bug will result in a grossly low IAS that bears no resemblance to your real IAS. The German ASI's are not "afflicted" by this bug.

The current bug renders the RAF ASI totally useless as a manoeuvre/energy cue. its only useful in 1G flight.

Here's a quote from the Spitfire, Hurricane, Curtis and 109E trial carried out by the Germans at E-Stelle Rechlin.

"Before tuning fights with the ME109E, it must be noted that in every case, that all 3 foreign planes have significantly smaller turning circles and turning times"


Just thought I'd throw that in..

Thank you MusseMus, that is very interesting!

In previous speed tests I put in the phrase that these comparisons were only valid if a 109 and Spit flying side by side showed the same speeds on their gauges. From your tests it looks like the answer is no! From flying in ATAG it is clear that 109s show a large speed advantage at all alts but perhaps not as much as the gayges suggest :(

camber

Thank you Camber!

My test was not very scientific because I only ran it 3 times and maybe the distance was a little short :) I would like to see if others get similar results.
It would also be interesting if 2 pilots could run side by side online and compare their speed gauget readings.
It would be good news if the speed difference between the COD spit & 109 is smaller than we thought :grin:

You may like to know that (deep breath):

Z values for IAS, TAS are given in 'world co-ordinates' units, e.g. 130.5 means 130.5 world co-ordinate units. I did some tests of distances on the CoD map versus Google Earth and to cut a long story short 'world co-ordinates' are effectively in meters, e.g. if you subtract one from another (using pythagoras unless you travelled perfectly east or west) the distance is in metres.

In one set of Spitfire tests I did I registered 249.83mph (402.06kph) on the IAS gauge at 10,000 feet (thats a scripted-out value that is fed to the gauge graphic, the needle can't be read that accurately and the tooltip rounds to whole numbers). Using rough conversion 2% per 000 feet that's 299.79mph TAS or 482.47kph TAS. More accurately using Density altitude that calculates as 290.72mph TAS or 467.87kph TAS.

The Z values were 132.09 IAS and 134.92 TAS. Assuming these to be metres per second (nothing else fits) that's 475.52kph Z_IAS, 485.71kph Z_TAS.

More confusion because I understood the rough conversion to TAS is 2% per thousand feet which should put the Z_TAS at 475.52 * 1.2 = 570.62kph not 485.71. OR... Z_TAS should put Z_IAS at 485.71 / 1.2 = 404.76. If we trust Z_TAS the IAS begins to look right and Z_IAS wrong. If we trust Z_IAS the IAS gauge and Z_TAS are wrong. Conclusion? Who knows but Z_TAS and IAS gauge have more going for it, after all the IAS value has to come from somewhere.

so at 10,000ft
IAS mph....IAS kph.....Z_IAS kph......IAS kph (from Z_TAS) ...Z_TAS(kph).....TAS@D.A.(kph from IAS)
249.83......402.06........475.52.........404.76......................485.71.....................4 67.86 (remember TS@D.A. will be different because its calculated for a standard day)

Now you could argue that according to the Z_IAS value the Spitfire is travelling 18% faster than the IAS gauge says. Alternatively..... Z_TAS converted to IAS says the IAS gauge is near enough correct. If that's right then the small difference between IAS gauge and IAS from Z_TAS could be caused by atmosphere factors (standard day to CoD day).

We have to be sure we're testing these aircraft properly. With respect, "I tested it at 10,000 feet and it isn't as fast as it should be" is very subjective because:
1. It was being tested using the IAS gauge which now falls under suspicion (for ALL aircraft). Or does it?
2. It "isn't the same top speed as the historical" data because it isn't being tested at or converted to a 'standard day' which is how historical data is published. How many of you know that the default SL pressure for CoD on line is 995mb, not 1013.25 as on a standard day? And that doesn't take account of CoD's SL temperature which is never the standard day 15C.
3. We don't really know if/which IAS, Z_data or whatever is truly accurate but I'm more inclined to trust the Z data and particularly Z_TAS.

I have never tested the 109 but I will after the patch although it would be nice to have some other guys help.

The diagram is accurate and uses industry norms for determining aircraft performance. Its does not fit any aerodynamic science that the Spitfire shoudl realize a turn performance advantage under all conditions.

I admit I have limited knowledge about virtual airplanes. My expertise lies with the real ones.

fixed that for ya.

The key word being 'rough'

A few years back, while testing IL-2, I did a comparison between the gauge IAS to TAS values using the 'rough' conversion to the 'full' conversion using the IL-2 'internal' values obtained via SJacks ZINFOMOD.. I than graphed the two values side by side, at which point the word 'rough' came to light! In short this rule-of-thumb pilot real time in your head calculation is very 'rough', there are points (altitudes) where it is spot on, but there are other points (alts) where is is way off.

Hopefully the soon to be released 'readme' will shed some light on the subject, but like you, I am leaning towards using some of the Z data values.. at least when it comes to speed measurements. They do seem to agree with the real world data better, at least for the few planes I have tested.

For now my plan is to provide both the Z and I values and let the user decide which to use with my CoD analysis tools that I provide online at www.flightsimtesting.com

Definitely worth looking at -- good work. I see this question of airspeed gauge accuracy has been posed in the Questions thread, as it should be. Anything like this should be examined, IMHO, and I hope Ilya does. RAF aircraft need accurate instruments for navigation as well -- especially if cloud cover is someday introduced. Hopefully you will post a Bugtracker Report using your data as its basis.

Having said that, I must admit I'm not convinced that perceived major FM inequities lie just with simple instrument error. As the old saying goes, "Just because you're paranoid doesn't mean they're not out to get you.". The hundreds of hours (literally) most of us have virtually flown on type (for both sides) to believe this notwithstanding, the RAF models alone are hobbled with huge radiator drag, with radiator surface area assigned three times the surface area of the 109's TWO radiators combined, with the double whammy of the RAF rads being assigned a drag coefficient 40% greater than their 109 counterparts. This alone has the Spits and Hurries flying with a huge drogue chute behind them when the pilot tries to cool his glycol and oil even under normal operating conditions, let alone in a fast interception climb or actual combat.

Only when Engine Temperature Management is deactivated in the Realism Options do the Spits and 109's actually achieve parity in engine performance. By default, with ETM off, all radiators are closed (huge benefit for Spits, Hurries, small benefit for 109's), and all temps are now AI - regulated (again, huge benefit for RAF, smaller benefit for LW). This is wrong and must be corrected, instrument error or no instrument error.

The devs are aware of this, and they should be made aware of all instrument error -- including the dodgy Rate of Climb indicator in the RAF aircraft as well.

None of this is rocket science, it just remains if Ilya sees fit to order the corrections or not.

Plus, I want to emphasize how much I respect and support your hands on initiative and the work you've done, and sincerely wish for any and all instrument inaccuracies be fixed -- at least to authentic specs. I tend to agree with my colleague, Dutch, that if the radiator drag issue is remedied in the RAF aircraft that the FM's for both RAF and LW will be closer aligned in relative performance. And I certainly want accurate gauges!

Is this a fact or a feeling? I have the relevant radiator areas, so what are the figures and from where?

As I understand the indicators have "electric" and "mechanical" types in the sim. Could it be that real world RAF and LW preferred different type of instruments, and this is modelled (perhaps wrongly) in the sim?

only the RPM gauges.

Hey kufürst, Dutch put a wee post someplace about how thwy had measured this.. I don't have a link right now tho.

That could well be, I'm only reporting what others have measured in sim.

Hiya pstyle. I posted a video of the effect of radiator drag in the Spit alone. It's post #16 in this thread. This didn't actually measure the relative surface areas Snapper mentions.

Just thought I'd better clarify that. ;)

Roger, cheers for the correction.

I can't really know what you were trying to say, or what you are going to say, but you were exactly saying what I stated:I'm happy to see that you now are saying something much more meaningful.

The general error of the interpretation of a speed advantage is the assumption that the slower plane has to match the faster plane at all costs. That assumption is totally unrealistic.

The general trend is in fact that the faster plane has the biggest advantage while flying straight, true against both better climbers in a sustained climb or better turners in a sustained turn. Entering a climb or turn that will be matched by the opponent, will in return reduce the speed advantage. That's how it works in combat.

Do you dogfight in the real ones? :grin: Do you dogfight at least in the virtual ones? Apparently not - that's all I am saying. I appreciate your theoretical knowledge of a/c engineering but you're simply wrong here. Not with the physics, there is nothing to argue about - but everything else you're saying makes no sense from the fighter pilot's point of view.

Of course not but what you're saying has nothing to do with the ability of the aircraft to turn in a combat situation. You got it right with the best performance velocities - and that's all the turnfight is. The fact that the 109 at say 400km/h can turn better than a Spitfire at say 250km/h is irrelevant. Useful in combat, but not for turnfight. It's called 'turn and burn' where the opponents get the best use of turn rate advantage. In this particular case, Spitfire has got the advantage.

Lighter with the same power = better climbrate but not necessarily better turnrate in typical combat situations. The Spitfire though could still outturn the 109

If you could perhaps describe how exactly would you outturn a Spitfire Mk.I in a Bf 109E, I am very interested. Everything you are saying is true but you would be dead in a turnfight because you're wrong about what is important in actual combat.

Crumpp, can you advise the source of your graph data? Cheers.

Parasitic drag is easy to approximate. The 109E needs less power at all altitudes to achieve the same or higher speeds (check for example the power available / speed reached at FTH. The Merlin III has a bit more power, yet both aircraft reach the same speed, 570 kph, which clearly points to less parasitic drag on the 109E.) This is true for the Emil/Mark I., and even more so to later variants. The 109G for example is about 30 kph faster on the same power, the 109K is about 40 kph faster on the same power.

You seem to have missed the "at high speed" part. ;)

And yes, the 262 does outclimb and outturn every prop job at high speed. It is simply to understand, say a Mustang has a top speed of about 600-630 kph even at +25 lbs boost. At this speed it is pulling 1G, drag is about minimal (almost entirely parasitic drag), and thrust equals total drag. It has no excess thrust. If it starts to turn, induced drag and so total will increase, and since the aircraft has no thrust reserves, it will start to decelerate, and loose speed. Its incapable of pulling any sort of sustained turn.

The 262 at about 600 kph still has a LOT of excess thrust - enough for another 230 kph. If it starts to turn, induced drag and so total drag will increase the same, BUT since the aircraft has no thrust reserves, it can use this excess thrust to overcome excess thrust in say, a 2 g turn. The turn is not very fast but its still a steady turn and the aircraft maintains speed.

See attachment for Spit IX. The Spit IX was an excellent turner and runs circles around the 262 at lower speeds. Come 500 kph, and the Spit is simply running out of thrust, can hardly turn at all, while the 262 can still pull a fairly decent turn. The Spits only hope is to go for an instantanous turn and hope for snapshot a few seconds before it blows all speed and becomes hapless. Its an extreme example, but demonstrates very well how things can get very different at high speed where one aircraft has a speed advantage.

Hi Robo!

I guess there is some kind of misunderstand, what I meant is when two aircraft turn at (the same) high speed, and one of them is faster. In these circumstances the curves change to the favour of the aircraft with more excess thrust (generally speaking, the faster aircraft). See the Mark Vc vs. 190A-5 turn curve. Again the Mark V runs circles around the 190A-5 at lower speeds. Come 450 kph, and the Spit is simply running out of thrust, can hardly turn at all, while the 190A-5 can still pull a fairly decent turn. The Spits only hope is to go for an instantanous turn and hope for snapshot a few seconds before it blows all speed and becomes hapless.

In sustained turns - no. Few if any aircraft could pull more than 2.5 g, some of the best like the Mark IX at +25 could hope to pull around 3 g and sustain airspeed. 3 g is very easy to pull even in a 109 with one hand, and blackout doesnt start until about 5 g. This the best turn possible at about 270 kph, at higher speeds the aircraft can pull even less, so g load is not a factor - unless you are going for an unsustained turn (lead pursuit) at which you blow speed to get a snapshot.

Obviously, this rarely happens in RL (or virtual skies) because you don't want to burn all your Es in a sustained turn, especially so in a 109.



Bad tactics. ;) Spitfires are tougher nut to crack, because they are about as fast as 109s - but for example against Hurricanes, which are much slower, a slow turn above 350 km/h might bring surprising results. The Hurri may try to blow speed, but that's usually a death sentence against a good pilot who knows how to exploit superior E-state.

It simply has much more excess thurst at high speed - hence it can maintain a sustained turn while the P-51 cannot at all - provided both aircraft are at high speed.

So are you suggesting aircraft can't turn without thrust?......so every glider I have seen change direction is purely my imagination?

surely you really mean to say the Spitfire will simply loose some ground, but it will without doubt still be able to turn.........some of these theories are getting bizarre.

It is a spreadsheet that calculates turn performance I made.

It is a sophisticated analytical tool that determines relative turn performance using standard incompressible flow theory. That was the predominate theory in use during WWII and is the same one used by the RAE.

By using EAS, all you have to adjust power production and you are in the ballpark for the Indicated Airspeed you should see performance.

I did it that way so it would be useful for the game. If you know the PEC, it is not hard to have the spreadsheet convert EAS to IAS directly.

It takes a little time but it can reworked for any aircraft.

Now we have to teach people the basics.

Aircraft cannot sustain performance without excess thrust and the forces in balance.

Any airplane without excess thrust can use gravity and momentum to achieve instantenous performance.

A glider uses gravity to propel itself which is why we don't use them on transatlantic flights. They exist in a purely instantenous performance condition. They cannot sustain performance under the power of gravity alone and must constantly trade altitude for airspeed without an alternate form of energy.

Gliders seek an alternate form of energy in the form of rising air currents to stay aloft.

http://www.mansfieldct.org/Schools/M...ightglider.htm

Bongodriver, try to make a turn from maximum level speed in an airplane maintaining both airspeed and altitude.

no mate he means (i think if i got it right) turning without loosing speed. any spit pilot can turn and loose a EA on his tale in clod but will loose speed instantly. he is talkign about going into a turn and keeping the turn without loosing speed. which isnt that bigger deal imo

this isnt all bad for the spit tho as this can be used so the plane behind overshoots and misses, i.e turning inside his turn so he cant get guns on you. puts you out of the fight but also keeps you alive, at least a while.
a 109 couldnt do this to a spit, this is why you go into a fight with a 109 always with higher energy or dont bother at all, so you can afford to loose that speed.

The readers understand that a better climb rate is indicative of more excess thrust?

Once again, the Spitfire shines in lift limited performance while the Bf-109 shines in thrust limited performance.

Any airplane can do this to another airplane.