Lippert,
Did they use that term in WWII?

I always thought that it came around the time of the Viet Nam world when the USAF (at least) had to learn again about air to air combat and the need for cannons on aircraft!

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“The first lesson is that you can't lose a war if you have command of the air,
and you can't win a war if you haven't.” - General Jimmy Doolittle

Two Japanese planes that could probably beat it given equal pilots are the Ki 84 Hayate and the N1K2J Shiden-Kai. I have read of at least several mock dogfights held post war between the Hayate and a P-51D-25-NA and P-47D-35-RA at Middletown Air Depot in Pennslyvaina where the Mustang and Thunderbolt came off the loser each time and the Ki 84 actually proved faster in level flight than either plane.

No, the term is from long after WWII. Energy Maneuverability is born from Col John R. Boyd, an Air Force pilot during Korea, he came up with a way to quantify the maneuvering potential of an aircraft in terms of its energy. He started pushing his work in the mid 70s and the F-15 and F-16 were the first aircraft designed with energy conservation in mind. Today, we use it almost exclusively as a means of comparing aircraft performance to determine where each aircraft has an advantage over the other in air combat maneuvering (dogfighting).

There's more to an aircraft's dogfighting ability than just "max speed" or "max power". It is a delicate balance of efficiency in lift to drag ratio, peak power available, and min weight. Together all these energy considerations can be plotted as airspeed versus turn rate to determine an aircraft's turning ability. If you google "energy maneuverability" you will likely find some charts such as these. I do even believe that there are some for the Mustang and Spitfire out there. I don't quite trust those, however, since they are based on simulation testing, and not on actual mathematical derivation from the engineering data.

The point I'm trying to make is that this question could be answered by the generation of some simple energy maneuverability diagrams and their compairson. I will try to throw some together over the weekend. I've made more than a few of these while working on my undergrad.

Attached is a paper I wrote about a year ago for my masters regarding a similar analysis for WWI aircraft.

Attached Files

Lippert-Research-AW500.pdf (746.4 KB, 7 views)

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"The Marines I have seen around the world have the cleanest bodies, the filthiest minds, the highest morale, and the lowest morals of any group of animals I have ever seen. Thank God for the United States Marine Corps!" Eleanor Roosevelt

Mind if I print it? I'd really need to read it a bit more carefully than I can online. Looks like a good beginning on the subject.

@ Lippert
For WII times I think they called it energy conservation or high speed maneuverability.

More or less it boiled down at how much energy did a given plane bleeded when for example, turn at best turning speed (sometimes I read corner speed : best turnrate/drag tradeoff) or climb at best climb speed for a given altitude.

The they compared it to the plane's engine acceleration power and dive acceleration, and then they knew which of 2 given planes, both maneuvering against each other so they neutralize the other one, would end up at with an energy advantage big enough to win the fight.

Of course, it's nearly impossible to have exact figure about how much speed did plane X bleed when turning flat at altitude Y and speed Z and turnrate Z' and then get the figure for all possible speeds, altitudes, turnrates, and the result implies that both airplanes start the fight at equal energy, only do maneuvers in the given maneuver's optimal enveloppe and make no tactical mistake.

And the most important factor was the topspeed a.k.a. the max amount of energy you can store in your "bank" while bleeding zero.

Pilots and tacticians had all this in mind well before Korean war, for example the high yoyo or chandelle maneuver ; lag pursuit or boom and zoom tactics result of energy conservation concern, even if they were maybe not well theorized at the time, it was easy to 'feel' inside the planes.

Another example is the US pilots in the Pacific "out-maneuvering" zeroes with P-38.

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T.A. : Yeah, print away - it's rather verbose.

Choca: The thing about energy maneuverability, however, is that you CAN predict how many knots you'll bleed per second, or how much altitude you'll lose trying to maintain that particular turn rate, depending how the charts are prepared. That's what made it superior to previous theories on energy management. There was work done on energy considerations and thermodynamic models for aircraft performance as early as the 1930s bu guys like Rutowski and others - I have some copies of their original work in my research libary. What made Boyd's E-M so important was the form of presentation and additional information it presented. Granted, each chart only really shows an instant in time, but you can pull trends from them that show the general turning dogfight performance of the aircraft.

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"The Marines I have seen around the world have the cleanest bodies, the filthiest minds, the highest morale, and the lowest morals of any group of animals I have ever seen. Thank God for the United States Marine Corps!" Eleanor Roosevelt

you guys mind if i apply work bench logic regarding maneuverability? i used to build model planes.

menuverability in a plane is engineered instability. the 'safest' and most stable plane would handle like a feight train in mid-air and just have enough deviation to allow it to take off and land. for a given engine power and thrust ratio:

1. the distance between the trailing edge of the wings and the leading edge of the horizontal stabilizers, measured using multiples of maximum width of the wings, determines stability at level flight. the shorter it is, the bigger the tendency for the plane to pitch up or down. it will also loop tigher in a turn.

2. the farther back one's center of gravity moves along the fuselage, the higher the risk of stalling and yaw movement. bring it closer to the nose and you have great diving speed but difficulty in pulling out.

3. rolling rate depends largely on two things: tip-to-tip length of the wings versus total fuselage length and also the severity of dihedrals on the wings (how much they angle up from horizontal.)

4. wing length (actually wing area) also influences the tightness of one's turn and loop.

as far as i can see, the mustang-d was engineered with too much instability in for its power. these were corrected in part on the mustang-h (bigger rudder to contol yaw, slightly longer distance from wing to rudder, etc.)

If I do Lippert you might not want the resulting posts.... I have a tendancy to pick through OR stuff and mathematical simulation with a lice comb if you follow me. My last was demolishing some of the Dupuy Institute guys on their TDNM / QJM modelling of warfare.

I'm still hoping you could post some of that demolition work, T.A. I've been wondering about the veracity of Depuy's stuff for a while, but I don't know his actual model, so I can't punch holes in it.

Here's a short discussion on Dupuy's QJM outcomes modelling:

Well, in my case, is that analytically and mathematically it makes no sense. Unlike many, I have taken alot of time going through the mass of linear equations used in Dupuy's QJM. I will not discuss here the merits of his weapons values assessment in the TLI/OLI system, but rather the outcomes of the model as these are the most important part of the system as a whole.

With the QJM Dupuy offers several different measures of outcomes:

Frist, there is the direct outcomes from the QJM where the calculated OLI combat potential is compared (see equations 12 & 13 in NP&W) given as P/P.
Next, Dupuy gives two stand-alone equations for "Spacial Effectiveness" (eq 14) and "Casualty Effectiveness" (eq 15). These are then combined, additively, to a chosen "Mission Accomplishment Factor" with a value of 0 - 10. Note, that this last subjective value often dominates the equation of mission effectiveness.
The results for each side, R, are then compared by subtraction of the defender's value from that of the attacker.
The two results above are then further compared using the equations:

(R-R)/5 = P/P-1 or P/P = (R-R)/6

Note, that neither of these equations is actually such. P/P and R-R are vastly different values which the constants do not balance.
Dupuy also uses a graphical presentation of these values in figure 5-1 introducing the concept of "The Normal Battle Line." By Substitution of x for P/P and y for R-R we find:

y = 5x - 5 and y = 6x from the above equations.

And, dy/dx is 5 and 6 respectively for the above. This means, as figure 5-1 shows, that the Normal Battle Line is linear with a slope of 5 or 6 depending on the equation used. Figure 5-1 shows this as a slope of 5 by simple plotting of the line. Therefore the second equation gives erronious values of this line by observed caluclation as shown.
In Equation 23 Dupuy introduces the "Score of Effectiveness." THis is another stand-alone evaluation. He follows this up with the "Combat Effectiveness Value" (CEV) defined as PR/PR and R/R for the CEV average. He then refines these equations into the "Effective Power Ratio" using the equation PR/PR = (R-R)/6. This is a refinement of the above Normal Battle Line equation above, obviously. It also by extension is erronious. Setting any of these equations equal to zero also results in a false answer, as none are equalities.
Basically, Dupuy's QJM is flawed mathematically to a point where the results are largely, if not completely, irrelevant. That is my objection to his system, not that it makes some allusion to the German Wehrmacht having some "quantified" superiority.

What's your background other than Navy TA? Feel free to have at it with the paper - it was written for a non engineering class and was hardly any of my better work. But it's one set of calculations based on resonable assumptions and baselines given the information I had. I in no way guarantee it to be 100% spot on, but a good representation of the trends of each aircraft.

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"The Marines I have seen around the world have the cleanest bodies, the filthiest minds, the highest morale, and the lowest morals of any group of animals I have ever seen. Thank God for the United States Marine Corps!" Eleanor Roosevelt