Aces High Bulletin Board
Help and Support Forums => Help and Training => Topic started by: McQ on March 05, 2002, 11:57:09 AM
-
HI ALL
I'm interested in making a E-M chart(s) for my favorite plane(s)(109s and 190s) in AH. My problem is I don't know how to draw
the "sustained turn" curve. What figures, numbers and equations
do I need,where do I find'em and how do I use'em.
Thnx for any replies.
-
McQ
You begin by choosing the parameters for the chart. An EM chart is only "good" for a particular set of parameters. These are normally a given weight, altitude, and power setting...this is often given as "50% fuel, sea level, and WEP" or whatever numbers you want.
An EM diagram is sometimes referred to as a "maneuver diagram", the reason being is that the data points on the chart are derived from changing airspeed and G values. The chart is bounded on the left by the stall line, on the top by the max G line, and on the right by the max speed line.
Any point inside these boundaries represent some combination of airspeed and G (since altitude is being held constant).
What we are really looking at in these charts is the effect of drag on the plane's ability to produce thrust. Sometimes the plane has excess thrust for a given G load, and sometimes it doesn't. There will be a point where for a given G and airspeed that the plane can just hold that value and not accelerate or slow down.
That point is called the "sustained power" point...also referred to as the Ps=0 or "excess specific power equals zero" point (Ps is pronounce "Pee sub ess"). If we take all the G and airspeed combinations and link them together, we end up with a line in the chart known as the Zero Ps line...a line that represents points where the plane will not speed up or slow down for the given conditions.
Fine, you say! Now, how do I find this line?
Not with equations in our sims! Only through trial and error...and that is a long and difficult process. You literally have to fly the sim under the conditions you choose and repeat the process over and over to get enough data to estimate the Ps=0 line.
My buddy Leon Smith is real good at this, and he might be able to help you.
E-mail him at badboy@netcomuk.co.uk and tell him I sent you!
Andy
-
HEY ANDY
Thnx for the prompt reply.
I do have a lot of "Badboy"s articules and charts and I understand that they are for only one set of parameters. But what if i use AIS instead of TAS, that would take the alt. out of the equation,right? After all your stall speed stays the same, no matter what your Alt. is, right?I want to learn to fly one plane well and figured performance chart will help and thnx to Leroy i have now charts for Spit,Pony and others.I fly one plane one fuel load and one loadout so mine parameters stay more less the same.
I just finish reading his piece about Officer Prune and to add to my dilema he's got one more curve on a chart.The D/L line. Now is it safe to say that my best climb speed is very close to it or is it the cruise speed or bast glide. Since in AH we do not have the last two I use the bast climb speed.
Speaking of testing, I just finish doing the stall speed tests for all the fighters in the game (now I know why 70-80% of the guys fly the Spit, lol) and that was no picknic. Since I'm recovering from minor surgery I have all the time to run more tests.I just hope Badboy gets off his rocking chair and make charts for my favorite plane(s) before I have to, lol.
(just kidding)
Now i'm going back to my test facility(basement)and get started on the sustained curves(I should've picked golf instead flying lol).
Thanks again Andy
-
Originally posted by McQ
HI ALL
I'm interested in making a E-M chart(s) for my favorite plane(s)(109s and 190s) in AH. My problem is I don't know how to draw
the "sustained turn" curve. What figures, numbers and equations
do I need,where do I find'em and how do I use'em.
Thnx for any replies.
I'm just preparing an analysis for the Invasion Sicily scenario and that includes the 109 G2 and G6 and the Fw190 A5. Here is a comparison for the Me109-G2 v Spit Mk IX at Sea Level and 25% fuel.
-
Same aircraft and configuration at 15,000ft.
-
Same aircraft and configuration at 30,000ft.
-
A couple of things to notice here is the way the turn circles become much larger up high, more importantly, notice how the advantage for the Spitfire increases with altitude. At 30k the G2 will stall before it can reach the 6g black out limit and can barely sustain a 1.7g turn. At this altitude the 109G2 drivers will need to cruise at top speed and catch the Spitfires during their climb out in order to have a chance. A maneuvering engagement at this altitude should be fairly decisive, in favor of the Spitfire, unless there happens to be a significant disparity in pilot skill.
The 109G6 and Fw190 A5 charts will be available very shortly with comparisons with the Spitfire, P-38L and P-47D11, along with other comparisons for most of the other fighters in the scenario.
Hope that helps.
Badboy
-
McQ
Sorry, no...you cannot avoid having to develop multiple charts if you vary your parameters.
Yes, a plane will stall at the same IAS regardless of altitude. But that fact is not connected to EM theory.
A plane's engine will be less powerful as altitude increases. This results in EM diagrams that "shrink" as altitude increases...the plane's performance is adversely affected by altitude increase.
I wish it were that easy...But it's not, unfortunately!
Andy
-
Great job Badboy.
--)-FLS----
Musketeers
-
WOW!!
This is outstandig!
Thanx alot guys. Badboy got 2 out of 4 of my favorite planes done already.How does he do that?One quick quastion; what Alt. intervals are practical?I'm gonna do the sea levels first and than pick an alttitude from AH's chart where my plane perform the bast. The "space" in between is where I don't know what's practical.One more quick comment and I get off the pot;between Badboy's science of flying and Andy's art of killing this is what makes wanna fly with you guys. Maybe in next version of AH Badboy's chart will be included.Hey, thnx a bunch guy.Out.
-
Once you have the diagrams, you've got about half the problem solved.
The other half is what do you do with them?
Ideas?
(I know...a loaded question!!)
:)
Andy
-
Hey Andy
Practice, practice and more practice and hoping the other guy 1: does not care about charts; all he wants to do is yank, bank and spray and 2:he practiced less then I have
or 3:your turn, Andy
Please give me more.
-
McQ
You don't get off the hook that easy? Consider these questions?
1. Energy vs angles fighter. Which is which?
2. What are the corner velocities? The zero Ps speeds?
3. Which fighter bleeds energy the fastest and how do you know that?
4. Who owns the "stall fighting" area? I hate that term, but many folks use it.
5. Is there anything in the chart to suggest that one plane has an ability to out climb the other, and when?
6. Is there an advantage in the charts? (one that can be measured and obtained by an average pilot).
Andy
-
HI Andy
You're killing me(lol) here.
Let me tell you why I'm so bend on having my own chart for my plane and those I fly against the most.
I want to fly mine plane on the edge of it's best performance, I want to get there faster then the other guy and I want to stay there longer then him.Now if I'm in my 109G6 and come across a Spit9(which is not hard at all) and I know where I am in respect to my best speeds for whatever move I want to make, be it a break turn or any other turn or move I want to do.Based on this I might employ your "high/ low wing" idea but first I have to know the speed I need and I get it from the chart.Now the Spit; let's say I'm putting along at 250mph(which is slightly higher than the corner speed for the G6,as far as I can tell) and I see the Spit on my tail, closing on me fast, guns blazing, tracers buzzing around my ears; I pee my pants.Or I make nice hard break turn,wait for the speed to get down to my best climb speed, climb 'till I get to best sustain speed and turn back toward the Spit.Since he was way too fast to turn with me he is doing very, very HI-YO-YO or better yet, he's yanking very hard to follow me.The Spit's chart will tell me what he can and can not do at his present speed.
Now to answer some your quastions:
1:To me it makes no differance which planes are energy planes and which are angels planes.I personally fly(try to) and treat all planes as energy planes, after all you can't go wrong being faster than the other guy.If you are angels will take care of themself,IMHO.
2:corner speeds; I simply multiply stall speed times square root of 6gs, in AH's case.But here is a small problem; we black out at 6gs and the corner speed is your new stall speed so if I pull 6gs at that speed I'll black out and stall, hardly a high performance turn.So I only pull 5gs on the G-meter, at least I'm turning, not spining, the zero Ps speeds; will ignore it for now.
3:Fighter that is flying well outside its best performance parameters bleeds energy the most, be it turning or climbing.How do I know? I don't but if I fly by the numbers and the other guy doesn't, he dies, if he does and I don't, I die but one of us will die for sure.
4:The energy fighter(lol)
5:I use the AH's own climb and speeds charts.
6:Is there an advantage in having the charts?
Yes.Consider this; if I know mine plane and can fly it on the edge all day long and at the same time knowing what your plane is capable of and seeing that you're not flying it right,you're mine.
Wow Andy, this turn in to "War and Peace".Sorry about that and besides, charts increase my quotiant of fun(lol).
Andy,thnx for your interest, input and guidence on this. I value your opinions and insights on many things.
Thank you again.
-
McQ
LOL!!
That wasn't an IQ test!! I wanted you to use Badboy's charts to answer those questions!
Take a look at those charts and see if you can determine the answers from them. If you can, great! If not, then we'll move another step forward.
I'll be gone for 2 days...see you then.
Andy
-
Originally posted by Andy Bush
McQ
You don't get off the hook that easy? Consider these questions?
1. Energy vs angles fighter. Which is which?
2. What are the corner velocities? The zero Ps speeds?
3. Which fighter bleeds energy the fastest and how do you know that?
4. Who owns the "stall fighting" area? I hate that term, but many folks use it.
5. Is there anything in the chart to suggest that one plane has an ability to out climb the other, and when?
6. Is there an advantage in the charts? (one that can be measured and obtained by an average pilot).
Andy
I want to answer the questions to see if I understand these charts. They are real pretty, but I'm not quite sure if I understand them or not. So here goes.
1. The Spitfire is always the 'turn fighter', because it can turn more DPS at any given speed below 300 mph. I also KNOW it has a smaller turning circle, and I'm pretty sure that chart shows it, but I don't know how to tell.
2. At sea level, the 109G2s corner velocity is roughly 160 mph, and it can turn 20 DPS going this speed. What I still don't know is how small the turn radius would be. At sea level, the Spitfires corner velocity is abput 145 mph, and it can turn about 22.5 DPS at this speed. Again, I still don't understand how I can get the turn radius from the chart... Those 600,700,800,900 on the right side have to mean something...
3. The 109 bleeds energy faster, but I know that just because I KNOW that... I don't know how to get it from the chart.
4. From experience, I'd say the Spitfire. From the chart, I'd really say the Spitfire, because it has a lower stall speed and it turns better at its stall speed than the 109 does.
5. Is there? I honestly don't know. The Spitfire IX and the G2 climb about the same until high altitude, then the Spitfire outclimbs the G2. But, I just know this already, so it isn't from the chart.
6. Well, that chart obviously shows that the Spitfire turns a lot better. Although, if I was the G2 driver I could know from reading the charts to keep my speed above 300 mph unless I felt like dying. I already know that without the chart though.
I REALLY want to understand these charts, because I think it'd make me a better pilot. I already consider myself a pretty good one, but I honestly just fly by the seat of my pants. I've no idea about any of the scientific explanations for doing the stuff I do (like always considered a low yo-yo to be 'cutting inside of their turn' by diving, and a high yo-yo to be 'cutting inside of their turn by climbing'- and thats exactly what I did (and still do)). I 'knew' what a high yo-yo was, but I didn't ever think about stuff like 'reducing closure rates' and 'decreasing the Angle off Target' and all that happy-crappy until I picked up Shaws book and started reading Andy Bush's posts. I'd like to become a more 'technical' pilot, and honestly know what my plane and the other one are capable of, rather than just always going by feel. Admittedly, going by feel can work pretty well too though.
-
Well, I'll take a crack at it and hopefully learn something! I'm going to use the 15k chart.
Originally posted by Andy Bush
McQ
You don't get off the hook that easy? Consider these questions?
1. Energy vs angles fighter. Which is which?
Well, it looks to me like the Spit is really both at most speeds. What I'm looking for is any place where the 109E can turn more degrees per second sustained than the Spit. There really isn't, aside from the very top of the speed range. The Spit almost always has a tighter turning circle, making the Spit the Angles fighter and the 109E the E fighter I think.
Originally posted by Andy Bush
2. What are the corner velocities? The zero Ps speeds?
I think that's where the sustained line meets the instantaneous turn line. On the 15k chart I call that about 170 Mph for the Spit and about 185 Mph for the 109. That should be the speed at which the maximum DPS and the smallest turn radius can be maintained.
Originally posted by Andy Bush
3. Which fighter bleeds energy the fastest and how do you know that?
I say the 109 bleeds energy the fastest based on the fact that it's sustained line is lower than the spits. I'm a bit unsure about this... I KNOW it bleeds speed faster, but I'm not sure my reasoning on the chart is correct.
Originally posted by Andy Bush
4. Who owns the "stall fighting" area? I hate that term, but many folks use it.
Assuming you mean who wins at low speeds, the Spit owns it clearly. It has much lower stall speeds, and much lower speed sustained turning performance.
Originally posted by Andy Bush
5. Is there anything in the chart to suggest that one plane has an ability to out climb the other, and when?
I have no clue on this one. Clearly there is some relation between maximum sustainable turn rates and climb ability, but I really can't figure it out. I'm not sure that the Spit's ability to to bleed less E will translate into climbing better at about 1G. I'm lost on this one.
Originally posted by Andy Bush
6. Is there an advantage in the charts? (one that can be measured and obtained by an average pilot).
Andy
I'm not sure what you mean. Knowing at what speeds your best turn performance can be obtained, and at what speeds your rate and/or radius is superior to the opponent is always an advantage. Simply put, I know that if I try to sustained turn with a spit while I'm flying a 109, I'm going to lose. The only way I'm going to beat a Spit in this situation is to be the Energy fighter, and use an energy advantage to exploit a short term rate advantage to make a shot on a slower Spitfire. Classic E fighting, lag pursuit, and a one circle fight is my only hope if I'm in a 109.
What your "average" pilot would take away from the chart I can't say...
-
Originally posted by Urchin
I also KNOW it has a smaller turning circle, and I'm pretty sure that chart shows it, but I don't know how to tell.
I've put some notes on this diagram, to help you read the turn radius information, and some notes that might help with Andy's other questions.
-
Ok, that cleared it up for the turn radius. I still don't get the P's thing though... how can you tell that the Spitfire will be able to climb at 540 fpm while being able to match the 109s turn?
EDIT: Ok, I maybe understand some of it now. I understand that you drew a line from the "spitfire" line so it passes through the 109s best turning 'point', and it would have extra energy since it isn't using all of its available lift for turning. I still don't understand how you arrived at the 540 fpm rate though.
-
A little background on the term "stall fighting". The first I remember hearing the term was in Air Warrior in '90. I believe that earlier versions of the sim allowed the spit (maybe other planes as well) to continue turn fighting at speeds below what shoulda been their stall speed. Was a common complaint.
Now I think it simply means a turn fight riding the edge of a stall.
-
My $0.02:
3. Which fighter bleeds energy the fastest and how do you know that?
I'm not sure that there is a general answer to this question, as phrased and based on the available information. Perhaps the question should be stated not in terms of "faster" but, rather, in terms of "g-load." To answer that question, at sea level, at speeds below about 280 mph, the Spit can pull more g's without burning energy than the 190. At speeds greater than about 280 mph, the relative energy situation of the two planes is reversed. To get a sense of how "fast" either of the planes burns E when flying "above" the Ps=0 line, we need to see the gradient formed by the negative Ps lines, I think.
5. Is there anything in the chart to suggest that one plane has an ability to out climb the other, and when?
I think that the ability of one plane to outclimb the other must be evaluated at a specific point in the flight envelope. At any point in one of the graphs, each plane is on some Ps curve. In other words, at each point in the graphs, the Spit and 109 are each either bleeding or accumulating energy at some rate, which we could read from the charts if they contained an unlimited number of Ps curves. I believe that whichever plane is accumulating energy faster (or, I suppose, losing it slower) can "outclimb" the other at that specific point in the flight envelope. Because we only have three Ps curves, it is hard to answer this question in general, unless we rely on personal simulation experience.
I still don't understand how you arrived at the 540 fpm rate though.
The 540 feet/minute is the result of the Spitfire flying on the +9 fps Ps curve. In other words, if the Spit flies on that curve for 60 seconds, it will have gained 9 feet/sec * 60 sec = 540 feet of altitude.
-
Originally posted by LoneStarBuckeye
I'm not sure that there is a general answer to this question, as phrased and based on the available information.
Generally, in these overlays, the aircraft with the higher zero Ps curve will hold its energy better at the same speed and load factor.
For example, if both aircraft are at the same point in the envelope, say they are both at 200mph and 4g, then the 109G2 will be flying at a point farther above its zero Ps curve. It will be deeper into its negative Ps region of the envelope so it will bleed energy more quickly.
Badboy
-
Badboy, excellent work as always. I loved the earlier articles you did at sim hq as well.
A couple of questions:
1. Your charts show the smallest turn radius happening at corner speed for all planes, yet Shaw's book states that smallest radius is well below corner speed, at around 1.5 times the power on stall speed. Also, the charts in the appendix of shaw's book show lines of constant radius as concave up curves, whereas your lines of constant radius appear to be straight lines.
My question is, who is right/wrong?
- Are your graphs accurate for turn radius for the flight models in the game, and the flight models are slightly wrong, OR:
- Are the flight models in the game accurate, and your constant radius lines should really be curved, OR
- Are the lines depicting the flight envelope slightly out on your diagrams, OR:
- Is shaw wrong?
The reason I think this is important is because shaw's book emphasises that when you get too far below your corner speed, you should use nose to nose turns because you will have a smaller turn radius than your opponent, but your graphs seem to indicate that this is not the case.
2. My second question: have you considered doing a complete set of these graphs for every plane in AH and publishing it? I would definately pay for this information!
-
My question would still be, how can you generate such a diagram by yourself. Which data and which formulas you need?
-
Originally posted by Naudet
My question would still be, how can you generate such a diagram by yourself. Which data and which formulas you need?
I made a few when I first started in AH. Check this thread:
http://www.hitechcreations.com/forums/showthread.php?s=&threadid=27538
Bunch of diagrams and the excel file I used are still there...
It is really simple to get the instantaneous turn rate curve, but I never did figure out a simple way to get the sustained turn rate.
-
Originally posted by Tub-o-lard
Badboy, excellent work as always. I loved the earlier articles you did at sim hq as well.
A couple of questions:
1. Your charts show the smallest turn radius happening at corner speed for all planes, yet Shaw's book states that smallest radius is well below corner speed, at around 1.5 times the power on stall speed. Also, the charts in the appendix of shaw's book show lines of constant radius as concave up curves, whereas your lines of constant radius appear to be straight lines.
I don't see what you see. Look at BadBoy's annotated chart and follow the turn radius lines. In both cases, the smallest turn radius is right where the planes fall off the 6G line. That is not what I call their corner speed which I define as the best sustained turning speed.... where the 0p's line intersects the turn line as noted on the chart. The best instantaneous turn rate is where the smallest turning radius is in both cases, which is right at the minimum speed that each plane can maintain 6Gs.
Now you mention something about power-on stall speed... well that is a decent ballpark to where the best sustained turning speed is on both aircraft, but that is NOT the best turning radius for either plane. Now I don't have Shaw's book in front of me, but I'm betting you are not looking at charts of WWII prop planes. It starts to make more sense if Shaw's charts you mention are of Jets, and that may in fact be the case. It could also explain the difference in some of the lines you are talking about.
Originally posted by Tub-o-lard
2. My second question: have you considered doing a complete set of these graphs for every plane in AH and publishing it? I would definately pay for this information!
I think what badboy really needs is a group of testers that will follow a methodology he sets and work through a test regime. He can do the graphs, but doing the testing itself is very time consuming. Maybe we could get a group of dedicated testers put together here and offer to do that?
-
Count me in
-
@haa, thanks a lot for the link, but i think i dont have the time nor the formula knowledge to do them by myself, i seems i just dont have the time at the moment do study this. :(
-
Originally posted by Tub-o-lard
1. Your charts show the smallest turn radius happening at corner speed for all planes, yet Shaw's book states that smallest radius is well below corner speed, at around 1.5 times the power on stall speed. Also, the charts in the appendix of shaw's book show lines of constant radius as concave up curves, whereas your lines of constant radius appear to be straight lines.
Shaw is right... And so am I :)
I think you are referring to Figure A-2 on page 391 of Shaw. If so, those curved lines are lines of constant g not turn radius, he has shown them as curves, and that is correct. On my diagrams, the lines of constant turn radius are perfectly straight, and that too is correct. The two diagrams are just different. If that was not the figure you were referring to, let me know which one you are looking at and I will try to explain it.
Shaw’s comment about the smallest turn radius occurring below corner speed is also true, but he was talking about the jets that were in service when he wrote that book. His statement needs to be qualified, because the aircraft he is referring to often have corner speeds that are higher than the top speed of the aircraft we are interested in. The difference is that for aircraft with corner speeds at such low Mach numbers, the smallest turn radius will effectively coincide with their corner velocity. That is just one of the very important differences between the performance of jet and prop aircraft. For example, the best sustained turn rate for a typical jet fighter does not occur at the lift limit, it often occurs at a speed close to and perhaps slightly lower than their corner speed, so when a jet driver max performs his aircraft he isn’t stall fighting like a prop driver, that’s why Shaw doesn’t mention it… But that doesn’t make either of us wrong, once again, we are both right :)
2. My second question: have you considered doing a complete set of these graphs for every plane in AH and publishing it? I would definately pay for this information!
I have already agreed to produce a complete set EM diagrams for Aces High. But it is a lot of work and these things take time. What Lephturn said :)
Badboy
-
Originally posted by Lephturn
I don't see what you see. Look at BadBoy's annotated chart and follow the turn radius lines. In both cases, the smallest turn radius is right where the planes fall off the 6G line. That is not what I call their corner speed which I define as the best sustained turning speed.... where the 0p's line intersects the turn line as noted on the chart. The best instantaneous turn rate is where the smallest turning radius is in both cases, which is right at the minimum speed that each plane can maintain 6Gs.
Now you mention something about power-on stall speed... well that is a decent ballpark to where the best sustained turning speed is on both aircraft, but that is NOT the best turning radius for either plane. Now I don't have Shaw's book in front of me, but I'm betting you are not looking at charts of WWII prop planes. It starts to make more sense if Shaw's charts you mention are of Jets, and that may in fact be the case. It could also explain the difference in some of the lines you are talking about.
Hmm ... I will have to go and re-read the appendix before I continue this discussion. You are probably right about the jet vs prop question. I will get back to you :)
The only thing that I am 100% sure of is that radius is proportional to velocity squared ... meaning the lines of constant radius should be parabolas, not straight lines. However, I have just relised that I am not looking at a graph of radius vs velocity, but rate versus velocity ... so I will keep my mouth shut on that one too :o
Originally posted by Lephturn
I think what badboy really needs is a group of testers that will follow a methodology he sets and work through a test regime. He can do the graphs, but doing the testing itself is very time consuming. Maybe we could get a group of dedicated testers put together here and offer to do that?
Definately count me in! I just need to know what data points are required and your preffered testing methodology to get them. I can spend a few hours a week on this. Just let me know.
-
Originally posted by Badboy
If that was not the figure you were referring to, let me know which one you are looking at and I will try to explain it.
I will check it when I get home and get back to you :)
Originally posted by Badboy
I have already agreed to produce a complete set EM diagrams for Aces High. But it is a lot of work and these things take time. What Lephturn said :)
As I said to Lephturn I would love to help out. If you need someone to do the monkey work of collecting data points please let me know.
-
BadBoy wouldn't we estimate the best sustained rate of turn for the 109 at 680 ft instead of 780 ft?
-
Originally posted by Tyro48
BadBoy wouldn't we estimate the best sustained rate of turn for the 109 at 680 ft instead of 780 ft?
Yep, well spotted.
Has been corrected... Thanks.
Badboy
-
Hi guys...good answers all!
Here's how I would sum up the three charts. First this...in RL, there was a minimum difference below which we considered the data to be irrelevant...meaning, that while the differences can be measured, how those differences played out in actual flight was considered negligible.
This is somewhat true of the zero Ps curves in these diagrams. At sea level, the differences are minimal...are more so at 15M', and become important at 30M'.
I've rounded off liberally when I did my numbers...if you get values that are slightly different, no big deal!
1. Energy vs angles. We begin by remembering that this categorization is always in relation to another plane. There is no such thing as a plane that is always one or the other.
Overall, the Spit has a higher zero Ps curve and relatively about as fast as the 109. Only at S.L. and above 310KTAS does the 109 have an overall speed and Ps advantage, and there the value is too small to be significant.
This leads me to consider the Spit a better angles fighter based upon this data. But that does not mean then that the 109 is the energy fighter. The 109 does not possess better energy (better zero Ps or max speeds) overall...so it becomes a lesser angles fighter. In this matchup, the Spit is simply the more maneuverable fighter.
2. Corner velocities. We know the definition....smallest radius and highest turn rate...it's where the chart peaks...the intersection of the stall line and the max G line. CV is different for each altitude. For the Spit, it varies from 210KTAS at S.L. to 360KTAS at 30M'. The 109 numbers are 230KTAS (S.L.) and 375KTAS (30M').
Please note that these are true airspeeds...not the airspeed that you see on the instrument panel (indicated airspeed).
Zero Ps speeds. Since the zero Ps line extends from the stall line out to the right, there is no such thing as "one" speed. We have to pick a variable such as G and then read the zero Ps speed that is associated with that value. You may choose to look at where the zero Ps line intersects the stall line and use that as a point of reference. If so, you determine that the Spit can fly slower and at a higher turn rate for a given G.
3. Energy bleed. One quick way to look at energy bleed is to look at the slope of the stall line. The more vertical the line, the greater the bleed in terms of change in turn rate and radius. A "flatter" stall line means a slower reduction in rate and radius.
In these charts, the slopes are pretty much equal...the two planes tend to lose energy at similar rates. Note...this does not say anything about specific performance...only that the two rates of energy decay are approximately equal.
4. "Stall Fighting". This one is pretty obvious. The Spit owns a significant area to the left of the 109 stall line at all altitudes. Using any point along the 109 stall line as a reference, the Spit can then fly at that speed and obtain a smaller radius and higher rate...or. and more importantly, it can fly at the same rate and get a smaller radius...this means it can fly INSIDE the 109 turn...and get a lead angle gun solution.
5. Climb performance. The Spit zero Ps curve is "higher" than the 109's. While the difference may not be great, this means that the Spit has excess energy to burn anywhere along the zero Ps line...this can be converted into a climb...if only for a short time. This is a "maneuvering" concept only...and does not necessarily mean one plane has an overall better climb rate.
6. Overall advantage? Goes to the Spit. Why? Overall better positive energy numbers. Go to the 109 zero Ps line where it meets the stall line. Now project that point upwards to the Spit stall line. That vertical difference can be measured and works out to be around 25-30% (rough overall averages of turn rate and radius values). This % gives a good idea of the overall pitch authority superiority that the Spit enjoys over the 109, according to these charts. The same technique can be used to measure the vertical difference between the 109 and the Spit zero Ps lines at a given speed. The overall results will be a smaller % but will still be in the Spit's favor. This technique gives a "snapshot' look at relative energy values.
Which leads me to the most important point. These findings are not "tactics"...they are only relative comparisons of energy performance. They MAY be used to inform the pilot of areas of superior performance, BUT they should not be used as a ruler for the conception and implementation of tactics.
In the final analysis, the pilot puts the plane where it needs to be to kill the bandit...anything else is rubbish. Some German guy said that a long time ago...and it's still true today. Another guy from USN TOPGUN also said something like "no pilot ever won a fight with a Ps chart"...or something like that!!
Read the charts with an educated eye...but fly to win, not to match up to a diagram!
Andy