Conservation of energy and pursuit tactics

[Badboy]

Originally posted by SKurj:
39.........

Sorry Skurj, I had it the wrong way up  

Refresh the page and you should see the new one.

Badboy

[Pinner]

41.1?

[Jay_76]

I'll try 45, for kicks.

Jay.

[Badboy]

Hi,

Jay, that's what most folk would say, but there is a shorter route.

Pinner, the answer is even less than that.

Badboy

[Dwarf]

Lotta misinformation in this thread.

Badboy's article, and pretty diagrams present a very nice theoretical fiction that simply does not translate into real life.

Is it possible to use the technique outlined to close on a fleeing opponent?  Not really.  

What would it take to make this technique work?  A perfectly frictionless environment.  With perfect interception of all datum points and then only if it were possible to perfectly convert from one Energy state (Kinetic Energy) to the other Energy state (Potential Energy or altitude), with no losses at any point in the procedure.

Friction (Drag) and varying Ps states throughout insure that the theory never becomes reality.

First you have to burn some E converting from straight flight to the dive (which can be neither too shallow nor too steep) and then you have to burn more E converting from the dive into the climb (which also has to be at only one perfect angle).  All the while Drag is more than negating every Erg you gain in the dive  (remember Drag increases with the square of the speed, not linearly - the difference in Drag between velocities of 500 fps and 525 fps is 25625 x Coefficient of Drag).

If you're very, very good and very very clean, you can minimize the Energy lost during the maneuver (zero G noseover at both ends), but there will always be an Energy loss when merely returning to your starting altitude.

The maneuver Badboy describes is useful for one thing and one thing only... minimum time to get from altitude A to altitude B with maximal energy gain at arrival.

When altitude A equals altitude B, such gyrations are only something to do to pass the time.

If you somehow manage to use something similar to catch a fleeing bandit, it wasn't because you did anything right (you didn't), but because the bad guy made even bigger mistakes than you did.

If the sim you're flying models things differently, there is something fundamentally wrong with the sim.

Dwarf
PS.  If you still want to believe in Badboy's fantasy, I've got a Perpetual Motion Machine I'm willing to sell for a really reasonable price... considering.




[This message has been edited by Dwarf (edited 02-06-2001).]

[Badboy]

Ok guys,

The way to figure out the quickest route around that container is to open it up and lay it out flat, in 2D where we can rely on the fact that the shortest distance between two points is a straight line. If we do that it looks like this:

   

You can see that it will fold up into the original container, and that the shortest route is exactly 40.

If you draw that line while it is flat and fold it back up, the shortest route looks like this:

   

You need to go diagonally to the bottom, cut across the corner, go diagonally up the side to the top, across the top and then diagonally down the far end. That's the shortest route and it isn't a straight line.

What has all that got to do with Air Combat?

Ok try to imagine this... Replace that container with the energy egg (That's the egg shaped surface that aircraft maneuver on)and replace the points on that container by points on the energy egg starting where you are, and ending where you want to be. Does the shape of route in that last problem bring the high yo-yo to mind? Could that be why it works so well?

   

Of course, with two moving aircraft we can't just measure distance anymore, because the situation is very dynamic. When I can produce a proof for the energy egg as convincing as the one for the rectangular container, it will make a nice article... until then it is just something interesting to think (or argue) about  


Badboy


[This message has been edited by Badboy (edited 02-06-2001).]

[Dwarf]

Nice example.  Well illustrated.

What do either it or the Hi Yo-Yo have to do with a situation where the bogey is not maneuvering and you have no overtake speed?
(Which IS the situation posed at the beginning of this thread)

Dwarf

[Badboy]

 

Originally posted by Dwarf:


Nice example.  Well illustrated.

Hi Dwarf,

Thanks, and Welcome to the boards!

 

What do either it or the Hi Yo-Yo have to do with a situation where the bogey is not maneuvering and you have no overtake speed?
(Which IS the situation posed at the beginning of this thread)

Dwarf

The two situations are really only very loosely related. I was responding to the point someone made about the shortest distance between two points. It was a digression.


When you say:

 

Start with Nuku's original proposition:
2 aircraft travelling the same direction at max velocity. Aircraft B is out of guns range of aircraft A, but has no overtake speed. Therefore aircraft B is at a state where Ps = 0. Its engine/prop/airframe is maxed out.

In that situation, of course I agree. I also agreed with Nuku when he said it. I didn't cover the "Both aircraft at max speed" situation, because although some fights may well end up there, they don't generally start there. However, that point was covered earlier in the thread.

I also believe that the situation Nuku described did not start that way either, regardless of his description. If it had started that way, it probably wouldn't have ended the way it did, as you rightly point out.

Badboy

[Dwarf]

 

Originally posted by Badboy:

I also believe that the situation Nuku described did not start that way either, regardless of his description. If it had started that way, it probably wouldn't have ended the way it did, as you rightly point out.

Badboy

OK.  Very glad we agree on the main point.
Thanks for your clarification.

The article on EM diagrams and how you use them is the best I've seen on that subject to date.  I join everybody else in offering my congratulations and my thanks.

Dwarf

[Dwarf]

Nuku -

Here's some additional possibilities that may explain what happened.

1. Netlag - you may have encountered a situation where, while it looked to you like the range had stabilized, he really still had some overtake.  The defender's view of things is always the least reliable.

2. Trim - while you believed you had the plane cleaned up as best it could be, you might have been just enough out-of-trim that you couldn't reach your true top speed while he could.

3. Weight - he may have been just enough lighter than you were that he could get an extra couple mph out of his airframe.

If he had a slight bit of overtake or a tiny bit higher top speed, he could exploit that by diving slightly to help him close.

Or it could be something else entirely, including other things that have been mentioned.

Dwarf

[niklas]

Badboy the second picture in your article is for SUPERSONIC JETS!!! It´s the typical curve for a supersonic jet, how to build up E. The dive is used (following the green line) to break through the sound barrier ! With a dive you break very fast through this barrier, and it is at the end faster to do this dive and then begin a supersonic climb.
First from sealevel a "normal" climb to 30-40k, until the macheffect shows up, then the dive, then the supersonic climb.

A 0G dive can bring you imo only ONCE nearer to an identical aircraft. Don´t forget: you push your stick forward (0G) and you begin a dive. But sooner or later you have to PULL to bring up your nose again. That means you MUST fly now a manoevre with more than 1G! And during this manoevre you loose the advantage that you got with 0G.

The flight path is longer
Drag increases with more speed (when you´re flying faster than a special speed, which is different for every aircraft (often close to best climbing speed))
During manoevering you have to deflect your control surfaces > drag
Diving means flying lower > higher air pressure > more drag
Thrust decreases with more speed for a propeller driven plane
0G advantage is nullified during pullout (1.xxG pullout)
Near topspeed the induced drag is very low compared to zero lift drag. The advantage of a 0G dive is not very big near topspeed. That is different if you start your dive from low speeds.

It is possible that a dive allow you to shoot from a closer distance, but only if you begin to shoot from a lower position. If you return to the same altitude your E-Status should be worse imo.

niklas

[Octavius]

Hello all,

Great posts being put up on this thread... but with all this knowledge of physics and whatnot, we should be nicknamed Einstein and be used plasma engines to zoom to the moon every day.  

One thing to keep in mind is that this is a physics engine that is very different.  The real world is based on simple rules that govern most all movement and behavior (ie conservation of energy and other laws).  The rules of the AH physics are bent and tweaked to improve playability and game balance.

But if real life physics were applied, the situation stated at the beginning probably could have been accomplished.  Conservation of energy.. ie energy is not destroyed or created, it is only converted into different forms.  Say the pursuing pilot puts his a/c into a slight dive to gain some sort of closure rate.  He is trading alt for speed.  In a matter of time, he will end up within the desired range of his opponent, yet at a lower altitude.  Should he pull up and trade speed for altitude, he should not end up in the starting position due to continuing thrust output.  He simply cannot trade his kinetic energy acquired from the dive back in for his exact original potential energy.  Energy is lost with the friction of the air (aka drag) over the aircraft.  The aircraft's thrust is making the plane constantly accelerate.  If there were no acceleration from thrust (terminal velocity achieved and no deceleration) the net energy lost would equal the net energy gained.  In otherwords, no accel, and no difference in PE and KE ratio as the pilot dives and climbs.  AH's engine is tweaked to allow energy to be conserved much more efficiently than a more realistic flight model would.  The KE is not converted properly as PE is obtained.  IN the end, you end up with more KE as you regain your original PE.  Crazy? Yes.  Almost seems as if AH has found the answer to perpetual motion!  

If this scenerio were to take place in a frictionless environment, small amounts of energy would not be lost.  Plus, without any friction the aircrafts would be constantly accelerating.  Anyway, excluding thrust and including a constant velocity.. if this maneuver of trading PE for KE, and later KE for PE, was to be executed, the object would end up with no change in distance from when it started.  

In the longrun, it all depends on how well you can determine how well you can conserve energy in your aircraft.  If you know the simple, basic rules of physics, you can use that to build your knowledge and understanding of most everything.. umm.. physical.

These are just my thoughts, please don't blast me if I'm wrong about any of it  , thanks.

------------------
-=///Octavius\\\=-
(aka Executor)
VMF-323 "Death Rattlers"
MAG-33
  Maz203@aol.com    

[This message has been edited by Octavius (edited 02-15-2001).]

[eagl]

Er...  My $.02

Badboy is pretty much correct.  To use what he's talking about, you either have to have a zillion hours in the plane and be VERY observant, or you need the Ps charts for all conditions (fuel weight, altitude, ext. stores, etc etc.)  It doesn't apply "only to jets", the curves just look a bit different thats all.

In practice, you use the charts to get some rules of thumb, and attempt to use those areas of the chart where you have the advantage. Realize that all it takes is for you to mis-assess your opponent's energy level a little bit, and all your planning did was make you die more intelligently.



------------------
eagl <squealing Pigs> BYA
Oink Oink To War!!!

[Suave1]

So the quickest route between two co-alt points is the shortest distance afterall . Not a roller coaster track . Octavius nailed it .

[This message has been edited by Suave1 (edited 02-17-2001).]

[Badboy]

Suave1,

Everything I've said is correct. If you read the previous posts carefully, you will see that. Also I believe that eagl is agreeing with me.

I simply can't address the faulty reasoning from other posters, there are just so many issues, it's overwhelming.

However, this thread was continued here:
 http://bbs.hitechcreations.com/smf/Smileys/default/Forum2/HTML/000611.html

That speaks for itself.

At the risk of repeating myself, the facts are:

1) It is possible to draw Ps (P sub s) curves for every aircraft, regardless of type.

2) It is possible to superimpose those curve onto Es (E sub s) curve.

3) The maximum energy state along any Ps curve is where it is tangent to the Es curve.

4) Such a point will always exist, regardless of aircraft type.

5) That point will lie somewhere between the best climb speed and the top speed for that alt.

6) The speed at that point yields the best energy transfer, call it V sub t or just Vt.

7) Best energy transfer gives you maximum energy gain in minimum time.

8) Every powered aircraft, regardless of type has such a Vt speed.

9) It can be used to gain an energy/time advantage over an aircraft that doesn’t use it.

10) If you start a fight below that speed energy transfer will be optimised by diving to it at 0g.

Those are facts!

The only remaining question is what are the actual Vt speeds for each aircraft. That, in my opinion, is the last remaining piece of the jigsaw. Unfortunately my current schedule means it may be a while before I can return to that problem.

Meanwhile The simple fact is that it does work. A lot of people have already confirmed it and have been doing it for a long time already. It is also rather easy to confirm. It doesn't just work in Aces High, it also works in Warbirds, Air Warrior, MSCFS, and EAW... Infact almost every other WWII sim since Chuck Yeager's Air Combat.

The Aerodynamic theory explained above predicts that it works, and the flight models of most of the sim's that replicate it are not so shabby that something that major would be wrong.

Lastly, on your question regarding the shortest distance between two points... After reading these boards I could easily believe that the shortest distance between some folk's brains and their mouths is via their arse, and I agree that would disprove my theory  

Despite that, I believe the example I posted previously with the box and the energy egg is sound. As yet, I haven't seen a better explanation for why the yo-yo works so effectively... unless of course you intend to post one?


Badboy


[This message has been edited by Badboy (edited 02-17-2001).]