E-m Charts

[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.

[Andy Bush]

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

[McQ]

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

[Badboy]

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.

[Badboy]

Same aircraft and configuration at 15,000ft.

[Badboy]

Same aircraft and configuration at 30,000ft.

[Badboy]

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

[Andy Bush]

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

[FLS]

Great job Badboy.

--)-FLS----
Musketeers

[McQ]

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.

[Andy Bush]

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

[McQ]

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.

[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

[McQ]

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.

[Andy Bush]

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