Author Topic: New "E" Management Article (Read 476 times)

Westy · « **on:** February 05, 2001, 05:24:00 PM »

http://www.simhq.com/simhq3/sims/air_combat/energymgmt/

Enjoy. I certainly am!

-Westy

bowser · « **Reply #1 on:** February 05, 2001, 06:01:00 PM »

Great point at the beginning.."it's the pilot, not the plane..". Simple point, yet so many seem to disregard it.
I sometimes get a little too relaxed against certain plane types, figuring "no problem". Of course that's when I run into a pilot who really knows his stuff, and he proceeds to hand my butt to me!

bowser

Badboy · « **Reply #2 on:** February 06, 2001, 12:53:00 PM »

Quote

Originally posted by bowser:
I sometimes get a little too relaxed against certain plane types, figuring "no problem". Of course that's when I run into a pilot who really knows his stuff, and he proceeds to hand my butt to me!
bowser

You too eh? Don't you just hate it when that happens?

Badboy

Lephturn · « **Reply #3 on:** February 06, 2001, 01:27:00 PM »

Great article Badboy!

It's really nice having the "print this" feature too. I'm keeping a hard copy of this one, and handing the link out all over the place! Thanks!

------------------
Lephturn - Chief Trainer
A member of The Flying Pigs http://www.flyingpigs.com

"A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"

Jigster · « **Reply #4 on:** February 06, 2001, 02:09:00 PM »

Quote

Originally posted by bowser:
Great point at the beginning.."it's the pilot, not the plane..". Simple point, yet so many seem to disregard it.
I sometimes get a little too relaxed against certain plane types, figuring "no problem". Of course that's when I run into a pilot who really knows his stuff, and he proceeds to hand my butt to me!

bowser

There is a certain joy in being a TBM Fighter pilot

Virage · « **Reply #5 on:** February 06, 2001, 04:08:00 PM »

Great article Badboy! Nothn like a good chart to get the juices flow'n

The obvious request... More Charts Please! I know your holding out!

And now for the questions (you asked for it):

How do you test the left boundary of the chart?

How do you test/define the curve of the sustained boundary?

How do you define the Ps lines?

Dwarf · « **Reply #6 on:** February 06, 2001, 05:45:00 PM »

Quote

Originally posted by Westy:
http://www.simhq.com/simhq3/sims/air_combat/energymgmt/

Enjoy. I certainly am!

-Westy

Don't enjoy it too much. Both the premise and the article are just plain wrong.

Squiggly lines on a chart don't make a thing true.

Dwarf

Hangtime · « **Reply #7 on:** February 06, 2001, 06:25:00 PM »

Care to expound on yer premise, oh great and ugly midget?

Great article, badboy.. thanks!

------------------
Hang
1st/AG "Bishlanders" << Recruiting!!

Westy · « **Reply #8 on:** February 06, 2001, 06:37:00 PM »

Dwarf, you just registered on this board today, have had an amazing three posts and your profile is completely blank.
Now.
I'm supposed to take those credentials and compare then to "Badboy" who I've "known" for over three years? A guy who has an immense passion for this hobby, has written mounds of extremely well read articles and who's never had a problem backing up anything he makes a statement on?

-Westy

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

Dwarf · « **Reply #9 on:** February 06, 2001, 07:58:00 PM »

Nope -

I'm not asking anyone to take anything on faith. Simply think the problem through. Or, if that's not enough, do the math.

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.

The only way it can achieve a state where Ps > 0 is to slow down. Any acceleration will create a state where Ps < 0, and the only way it has to accelerate is to dive.

Diving both increases the air density within which it operates, and the speed with which it moves through that air. Both of which dramatically increase the Drag it generates. The instant it ceases to dive, it starts to lose the velocity it gained because the engine/prop/airframe simply can't sustain the higher speed/drag, otherwise it would continue accellerating at the altitude from which it started.

If it remains at that new altitude, it will eventually return to the speed at which it started. Net Energy loss, the difference in altitude.

If it attempts to climb back to where it started from it will lose more than the difference between its new speed and the velocity it started with. Remember it takes power to climb, and from the instant it started diving until it returns to its starting velocity it operates at [EDIT] an engine/prop [/EDIT] Ps < 0 and increased Drag. Net Energy loss the difference in speed.

Drag increases with the square of the speed. It takes 4 times the power to go twice as fast.

That simple fact kills you both on the way down and on the way back up. [EDIT] Even the most skillful glider pilot can't stay aloft indefinately in the absence of any updrafts.[/EDIT]

If you're both already at the same altitude, going the same speed (as fast as you can), one guy can't catch the other by diving unless the first does something that causes him to slow down while remaining at the same altitude.

But, of course, you're free to believe whatever fantastical ideas you choose. I recommend the Tooth Fairy who is reputed to leave money.

Dwarf

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

Lephturn · « **Reply #10 on:** February 06, 2001, 08:13:00 PM »

Uh... I think your confused. The link Westy provided has nothing to do with Badboy's other article about the CoE chase. You are referring to this one I believe: http://www.simhq.com/simhq3/sims/air_combat/co-e_chase/

Quote

If you're both already at the same altitude, going the same speed (as fast as you can), one guy can't catch the other by diving unless the first does something that causes him to slow down while remaining at the same altitude.

I don't think we are all on the same page here. Of course, if both aircraft are at their maximum level speed, this won't work. This will only work if the planes are going the same speed (roughly), but that speed is well below their maximum. In this case both planes have excess power, and they are using their props to try and convert that extra power into energy. Badboy's point is that the propeller and engine system is more efficient at making that conversion at a fairly high speed. The result being that the plane that gets to this most efficient speed by diving, can more efficiently convert that extra power into energy.

I do not think the aerodynamics of the situation are as simple as you seem to believe. I think it's a valid theory, and one that seems to hold true in simulations like Aces High and Warbirds. It works, try it.

------------------
Lephturn - Chief Trainer
A member of The Flying Pigs http://www.flyingpigs.com

"A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"

Dwarf · « **Reply #11 on:** February 06, 2001, 08:41:00 PM »

It's certainly possible that I've confused two URLs from the same author.

Quote

Originally posted by Lephturn:
I do not think the aerodynamics of the situation are as simple as you seem to believe. I think it's a valid theory, and one that seems to hold true in simulations like Aces High and Warbirds. It works, try it.

Yes, the aerodynamics are that simple and that stark for prop aircraft.

The fact that such tactics may work in WB or AH, doesn't make them valid. It simply means that both sims need to work on their physics modeling.

Dwarf

Hangtime · « **Reply #12 on:** February 06, 2001, 08:45:00 PM »

Popcorn; anybody?

Dwarf · « **Reply #13 on:** February 06, 2001, 08:45:00 PM »

Apologies, Westy, and Badboy also. I have indeed got two different articles confused.

The one referenced here is on valid footing.

Dwarf

eagl · « **Reply #14 on:** February 06, 2001, 08:51:00 PM »

More important than simply diving for speed, is finding the best acceleration AOA for that aircraft. This applies not only to jets, but to all aircraft. Unfortunately the only example I have is for the F-15...

The best acceleration for that plane due to it's wing, is at a positive AOA. That means that at low speeds, it accelerates best below 1 G, and at higher speeds, it actually accelerates best above 1 G. Engine design (more efficient at low altitudes?), prop design (number of blades, length, pitch, twist, chord and aspect ratio, tip shape), engine thrust line, wing and stab angle of incidence, wing camber and airfoil shape, tail camber, amount of parasite drag, even surface texture, all affect how the plane performs at different speeds.

One definate benefit of diving after a running enemy is that for a while, you will be accelerating faster because at the lower G in the dive, you have lower induced drag. Similiar efficiencies can be seen in climbs due to part of the engine's thrust being used to cause the climb in addition to the wing's lift. This is why the best fuel efficient profile is a best-rate climb to near max altitude followed by a high alt cruise, followed by an idle power descent.

Lots of stuff works that isn't very obvious, and it's different for each plane.

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