E-m Charts

[Urchin]

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.

[Lephturn]

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...

[Badboy]

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.

[Urchin]

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.

[AKIron]

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.

[LoneStarBuckeye]

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.

[Badboy]

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

[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.

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!

[Naudet]

My question would still be, how can you generate such a diagram by yourself. Which data and which formulas you need?

[haa]

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.

[Lephturn]

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?

[McQ]

Count me in

[Naudet]

@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.

[Badboy]

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

[Tub-o-lard]

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

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.