Rate, Radius, Energy Egg

[pellik]

The other night COFalcon mentioned he was a little supprised I knew about the energy egg, a concept which apparently isn't well covered outside of the military. He even said I was the first civilian he's met who knows about the egg. At the time this sounded almost perposterous, as this is pretty much need to know for understanding the advanced moves in AH. There's really not much discussing this on the net, but there are a few good resources  if you dig for a few minutes.

You don't have to dig, however, I'm just gonna summarize it here anyway. I know this crap has all been covered before, much even by myself. But we here on the BBS are all about saying the same things over and over, and I'm not going to be the one to break the trend. I'm also going to rehash rate, radius, and corner speed.

Your plane's turn radius, how big the circle you  fly in when you  turn, is directly proportional to speed and G loading. The slower you go while holding constant G the smaller the radius. The problem is that when your speed gets too low the plane will stall in a hard pull far before it reaches it's structural limit for G loading. This results in an entire range of speeds with an equally small  turn radius.



The next consideration is of course turn rate. Turn rate is also directly proportional to speed and G loading. Detailed here:



These graphs combine to create the following:



Please note the single point marked "Corner of the flight envelope" in which both turn rate and radius are optimized. This is your best corner speed.

And now on to the egg. If any of you have taken highschool physics you'll recognize this image as a Free Body Diagram.



Does it say a plane with a maximum G loadout of 6 G is pulling 7 G? Yes.  "Radial G" is the vector sum of the G pulled by the plane and the G provided by gravity. As gravity becomes less diretly opposed to the intended change of direction for the plane more of that G loadout is used for turning, and less for keeping the plane flying. This difference  in turning enlongates the bottom of the loop and shortens the top, giving it an egg shape. Energy egg.

I warn you that using this in the MA is tricky, as it can be tough to keep your plane at corner speed with the incredibly low thrust we have to work with. But through mastering yoyos to control your speed you can use this to get a little more out of your plane. Please remember that turning harder is no substitute for turning smarter, so don't expect this to change things much if you're struggling to get things figured out.

This whole post is just paraphrasing from this.

-p.

[Flyboy]

great post pellik

[Simaril]

There are resources that list the climb rates for AH, and the max speeds at various altitudes -- are there any that have the corner speed for each AH plane?

[Clifra Jones]

Originally posted by Simaril
There are resources that list the climb rates for AH, and the max speeds at various altitudes -- are there any that have the corner speed for each AH plane?

Haven't found any. I have a list of corner speeds but It's not AH specific. I think it is RL based.

Basically Figure 1 in Pellik's post is similar to an EM diagram. I've seen these for various aricraft both real and virtual. Most of them have been for Warbirds of other sims.

You can create an Em chart if you know some basic information ragarding an aircraft. Primarily the structural limits, aerodynamic +/- G, Structural +/- G & airspeed. It also helps to know the level stall speed but is not necessary for calculating corner speed.

I would bet that the AH planes are fairly close to their RL equivelant in these limits so if you calculated an EM chart based on RL data it should be fairly close. The forumlas to do this are listed in the Appendix of Shaw's Air Combat book, the charts could be done in Excel.

This SimHQ article goes into this in some serious details regarding this subject.
http://www.simhq.com/_air/air_011a.html

Leon, charts differ slightly than the ones used by Pillik and by Shaw but they get to the same point.

Pellik, interesting quote from COFalcon, I read about the egg in some of the first articles I found regarding air combat. I wonder  how many of our brethren have never heard of it?

[pellik]

Netaces has many charts for climb rate and max speeds at various altitudes. Some are just excel spreadsheets, some have little java interfaces. They are all still AH1 data, but most of the numbers will still hold reasonably true. Aside from the spitV, new 38s, KI84, and possibly the 51 I don't think engine performance has changed much on the plane set.

I had seen the term "energy egg" come up several times in ACM pages. In almost every single one of them it was refering to the wrong concept. The reason I finally settled upon the explanation I did is because it was in an article from afsaftey magazine about the difficulty of pulling up.  

Speaking of which, afsafty is a good free magazine to download in pdf every month. It's full of stories from AF pilots of all different types. The current issue is about flying through storms and fog.

Digressing back to EM charts, finding them in AH is really quite simple on account of the game being full of whimpy 6g pilots. If only your pilot could do squats in the tower between flights and build some damn muscle on his legs to sqeeze that blood out. Because the pilot is pretty much always the weak link you can find corner speed by finding the slowest speed your pilot will black out at. Aside from wingovers, which few people can do in this game, radius stays pretty constant until you get above corner speed. Or at least I guess it does, as any real test is just too much of a pain in the ass.

-p.

[Spongebob]

It's like Deja-vu all over again:)   I was just explaining to my hangar-bangin' brother the other day how I got on his 6 so close on a merge (Vertical Lead Turn). I went into a couple other things including what you discuss here Pellik. I drew him a diagram of what to expect in a vertical move but was focused on the bottom of the loop that would connect together 2 energy eggs (now I know what to call them when we talk again - thanks Pellik). This is where your bandit hopefully dove to meet your vertical merge. If so, he (or possibly she in AH) is consequently in a dive and limited by G forces and speed, which work in tandem to flatten out his turn. At the same time, at the top of the loop, your getting the famous "gravity assist" and with any luck turning inside the bandit for a snapshot..or the very least gaining valuable degrees in your turn advantage.

So now next time I explain this I can say that this move gives you a momentary turn advantage of two extra Gs. This happens precisely at the moment when your upside down at the top of your loop and the bandit is at the bottom of his loop. Or:

Him at bottom of loop---> 6G blackout limit minus 1G gravity = 5G turn

You at the top of the loop---> 6G blackout limit plus 1G gravity (AKA Gravity Assist) =7G turn

After reading this post I can now explain technically what I knew before only intuitively.


Of course if you've done much research on ACM I suppose this is basic stuff. I told my brother that the best way to evaluate a pilot he merges with is to try to dive under him early-on to setup a vertical lead turn. If the bad guy matches your dive with one of his own, attempting the same move or just to keep you from gaining separation, then you know you are about to mix it up with a reasonably seasoned pilot. As a noob to ACM you can then consider your options - fight, die, and learn or ummm egress...

Anyhow, I handed him my copy of Shaw's book and told him that just like me, when he got to the chapter on rolling scissors, his head would probably explode:D

Magoo

[Clifra Jones]

Originally posted by Spongebob

Anyhow, I handed him my copy of Shaw's book and told him that just like me, when he got to the chapter on rolling scissors, his head would probably explode:D

Magoo

Just try reading that appendix more than once in a few days. 1st time I read that through I had to put the book down to stop the room from spinning.