Conservation of energy and pursuit tactics

[Nuku]

In two situations already, while extending away from a furball, I end up with a similar aircraft on my 6 (i.e. La5 vs La5, P-51 vs P-51).  With my aircraft cleaned up, with WEP going, I figure there is no way he'll be able to close the range to fire after the range has stabilized, with him level on my 6, static at 1.8 to 1.5.

Then, on these two occaisions, the pursuer does something I didn't think would work: they go into a shallow dive, trading altitude for airspeed.  This allows them to close the distance by about 200-300 yards (1.5 to 1.2 say) but they're below me.  Then they start a shallow climb back to my altitude.  This should slow them down, as they just trade the KE energy back for PE (alt).  By conservation of energy, I would expect them to end up back where they started, but I find that they GAINED distance on me (100 to 200 yards).

After about 3 or 4 of these, they've closed to under 1000 yards and can start firing.

I'm scratching my head here: WHERE did they get the extra energy??  The ups and downs of their sinusoidal flight path is definitely more distance than my straight-and-level flight.  My flaps were up, WEP was going, I was trimmed out, and I had no fuel tanks or ord strapped on.  

I've read that "unloading" the aircraft to zero-G is a good way to accelerate OUT of a fight, but I've never read that it's a good way to catch someone.  Can someone enlighten me on how this works?

[BBGunn]

The present flight model retains of lot of energy.  Some say too much.  An AC should slow down when climbing as you stated but in AH they don't seem to slow as much as in other sims/flight models after the AC gains E. I won't argue whether this is right or wrong- just seems to be the way it is.

[fscott]

This is some thing that has always bothered me also. There is no way this could happen in reality. As long as your sure your plane and his is traveling at the same speed.

Think of it as 2 cars side by side on 2 different roads. One road stays straight and level, the other road goes downhill then back up to the same level. In real life any energy the downhill car picked up would be lost on the uphill climb. Also, the distance becomes greater while the car goes downhill, so that also needs to be covered.

There are a few planes that retain E like forver. If I named them, we'd have another flame war. So, all I can say, the E model does need some neutering.

fscott

[bloom25]

A few things should be mentioned.  The la5's engine has a MUCH higher output if the plane is below 8k alt.  The p51 also has altitudes where it performs better.  The p51 is very sluggish below 15k.  Above 15k the next gear in the supercharger kicks in and performance increases.



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bloom25
THUNDERBIRDS

[funked]

In the long run the pursuer will lose ground with this technique.  But yes you can gain ground in the short term.

PS Conservation of energy doesn't apply - thrust and drag see to that.

[gatt]

Oh GAWD! Dont change the FM! I've just re-learned to fly and fight with this E-saving thing  

Jokes apart, try to do a landing pattern with no engine (say at 200mph TAS) and you'll understand how much E this FM retains.

[Dingy]

 

Originally posted by bloom25:
A few things should be mentioned.  The la5's engine has a MUCH higher output if the plane is below 8k alt.  The p51 also has altitudes where it performs better.  The p51 is very sluggish below 15k.  Above 15k the next gear in the supercharger kicks in and performance increases.

Good point, but just to clarify, the initial post pertained to like model planes.  Not different types of planes like 51 vs La5.

-Ding

[mrfish]

 

Originally posted by bloom25:
A few things should be mentioned.  The la5's engine has a MUCH higher output if the plane is below 8k alt.  The p51 also has altitudes where it performs better.

listen to this guy - i was cursin up a storm last night when he caught my p51 in an la-5!!

but....how did he....i was...oh never mind..*&%#

be mindful of what tactic you are using at what altitude, the speed might not be there for you as mentioned in this thread...
 

[J_A_B]

If the same plane, starting from the same E-state, can gain ground by a shallow dive followed by a shallow climb, then there is an error in the FM.

This sort of tactic should cause the plane to end up farther behind than he was to start with, and slower too.  

J_A_B

[Badboy]

 

Originally posted by Nuku:
I've read that "unloading" the aircraft to zero-G is a good way to accelerate OUT of a fight, but I've never read that it's a good way to catch someone.  Can someone enlighten me on how this works?

Hi Nuku

They were not simply unloading, and this is a valid and aerodynamically correct procedure. I believe the technique is part of current USAF tactical doctrine. It is so effective against a similar aircraft that I've even been called a cheat for being able to catch guys who started out of gun range with a slight E advantage.

I've just submitted an article that explains how and why it works to SimHQ and I'll post the link as soon as it goes live.

Badboy

[Badboy]

 

Originally posted by fscott:
This is some thing that has always bothered me also. There is no way this could happen in reality.
fscott

Hi fscott

It does happen in reality, and modern fighter pilots use that technique to good effect. I've been doing it for years. It has probably been so effective all this time because so few people know of it.

I hope my latest article will fix that.

Badboy

[Badboy]

 

Originally posted by funked:
In the long run the pursuer will lose ground with this technique.  But yes you can gain ground in the short term.

PS Conservation of energy doesn't apply - thrust and drag see to that.

Hi funked

The pilot in the example was not applying the technique correctly, or he wouldn't have been doing a saw tooth dive and climb. My guess is that he was doing that because he wasn't actually aware of the V numbers for  proper application, but even so, he made it work. The fact is that this does work in the long term, the longer it is applied the bigger the energy advantage becomes.

Also, conservation of energy always applies, you just can't ignore the thrust and drag. Factor them in, and everything will balance out nicely.

Badboy

[Badboy]

 

Originally posted by J_A_B:
If the same plane, starting from the same E-state, can gain ground by a shallow dive followed by a shallow climb, then there is an error in the FM.

This sort of tactic should cause the plane to end up farther behind than he was to start with, and slower too.  

J_A_B

Hi J_A_B

I believe the flight model is behaving correctly in this respect. Sorry to hold back on the details, but once you read how this works you won't just accept it, you will probably be using it yourself  

It is a situation that doesn't come up very often because when different aircraft types are involved, normal performance disparity can negate the effect. I only use it in a similar aircraft engagement and I've had good results with it.

A typical example might be after I've been unsuccessfully bounced by a pilot who then climbs away instead of using his energy advantage to press for the kill.

It is possible to eventually catch them, but only if they allow you to, and they probably will if they don't know how it works. When your adversary understands what you are doing it is very easy to prevent.

Badboy

[J_A_B]

Since I'm no Ph.D  and said what I did based only on my experience playing other simulators (quite a lot of them), I will assume that the people who posted that this IS possible are right.

To which I ask two things:

1.  How easy is this to accomplish in the real world, compared to how easy it is in the game?   Why wasn't this sort of tactic ever mentioned by WW2-era pilots?   Is this something which in the real world only applies to Jet aircraft with afterburners?

2.  Why does no other WW2 simulator allow this sort of tactic?  (aside from a console game I used to have)   Is this the sort of tactic that, while possible, wasn't practical with real WW2-era airplanes?


Thanks,


J_A_B

[Badboy]

Hi J_A_B


> Why wasn't this sort of tactic ever
> mentioned by WW2-era pilots?

I think similar aircraft engagements have been fairly rare, Spitfires have engaged other Spitfires, but that was after WWII. Even so, a protracted tail chase scenario was not very common, mainly because real pilots are much more fuel conscious than we are and an extending pilot would probably push the throttle past the wire, and push the manifold pressure to detonation. Few pilots would want to follow that, it's the sort of thing you only do if your life depends on it. Not to mention that a protracted chase is unwise if you care about survival, because it not only pinpoints your position to the bandits buddies, but it makes you very predictable. Also most real pilots who were serious about getting out of dodge, dived out of a fight, all the way to the deck if needed. In that situation it doesn't work anyway.
 
Also, the method used to predict that type of performance advantage wasn't developed for another twenty years, so they simply didn't know.

> Is this something which in the real world
> only applies to Jet aircraft with
> afterburners?

The theory applies equally well to both types, but arrived a little too late to make any difference to prop' fighters. It is my opinion that even had it been known, it would probably never have been of benefit. Flight sim pilots do many things that real pilots would never dream off... For us life is cheap  

That doesn't stop us taking advantage of the knowledge now. But even in our crowded arena, full of pilots doing the damndest things, the opportunity is still quite rare.

2.  Why does no other WW2 simulator allow this sort of tactic?

They do. I've used it effectively in three other online WWII simulations. Generally, I've only found it effective fighting real people flying similar aircraft.  

> Is this the sort of tactic that, while
> possible, wasn't practical with real
> WW2-era airplanes?

I think so.

Badboy