Ehm, is this possible?

[StSanta]

Yesterday, me and kirin were out in Ta-152s doing some hunting. We'd just done some "under the flak umbrella" fighting near an enemy cv between a22 and a25, and were now just hunting south of it.

After downing a Spit and an F4U, we gave chase, on the deck, to another f4u that was going really fast.

At any rate, kirin was faster than me and started to gain slowly on the F4U. I did a shallow climb to about 2k above Kirin, before realizing that I could maybe also get a shot. So I put nose down.

And to my surprise, I ended up going faster than kirin, and gaining on him.

Same gun loadout of course, same fuel loadout, both on wep. Only difference was that i did a slight climb and then a dive.

Laws of physics would suggest that this isn't possible (just drag alone would make me waste e in the climb that I cannot regain in a dive) so am wondering what the explanation is?

Very smooth flying from both of us, no jinking or anything, just straight ahead after the f4U.

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Von Santa
Staffelkapitän 9./JG 54 "Grünherz"
"If you return from a mission with a victory, but without your Rottenflieger, you have lost your battle."
- D. Hrabak, JG 54 "Grünherz"

[Animal]

You cant create energy from nowhere.
However, maybe the TA152 gains energy faster even at a slightly higher altittude wich made you pass Kirin by a bit.

[funked]

Drop me an email, funkedup@raf303.org, and I'll 'splain it to ya.

[Furious]

Funked,

Please explain it to all of us.

F.

[Hans]

The only variable I can think of is air preasure.  As you climb up, you enter thinner air and can go faster.

Untill your supercharger hits its max output and can no longer push more air into the engine to keep the engine preasure constant.

I don't think that was the case here though.  A shallow climb should slow you a bit.

Hans.

[MANDOBLE]

Santa, that is perfectly possible and you can do it with any plane, not only with Ta-152. In fact, this is the only way I know to catch a fast P51 at lo alt after a dive. You also have the "inverse" effect. Suppose you are 10k with a top speed of 300mph, you dive and come back to 10k, top speed 350 mph. In both cases, I dive or climb once I'm not building any extra speed due drag at level flight.

[Pei]

I've used this succesfully a number of times, including a situation when I was in an La7 trying to catch a low Tempest. They have a pretty good explanation of this in the fighter tactics section of simhq.

Pei

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We're fighting for this woman's honour, which is more than she ever did.

[Pepe]

As far as I read on this subject, this kind of movement (diving to gain speed, or climb slightly to dive then to gain speed) would work on jets, as they are more efficient as they move faster, and the gain in speed would mean gain on efficiency, and compensate the longer distance of the flight pattern. But not on prop planes, as prop drag increases with speed, exponentially, and negates any gain of e due to climb.

Cheers

Pepe

[This message has been edited by Pepe (edited 04-17-2001).]

[MANDOBLE]

Prop planes have an energy generator, the engine. At some point at level flight, the drag of the plane compensates the engine, so no more energy is gained, acceleration becomes null. But, climbing, your engine will be effective again building up more energy with a reduction of drag and speed, but in overal you've increased your energy state and you can covert it into more speed at the original altitude. The best way to do this is by diving and then climbing, but if you have no heigh to play with, you can climb and then dive. Of course, after some time, the drag will compensate the energy gained and the plane will slow down again. AFAIK, early jets had the opposite behaviour, the engine just loose too much effectivity climbing in the same situations, so, keeping them at level flight or diving was the only way to really gain speed quickly.

[Sandman_SBM]

Pei, are you speaking about this?
 http://www.simhq.com/simhq3/sims/air_combat/energymgmt/

[Lephturn]

There are several factors at work here, but the basics are related to drag, propeller efficiency, and top speed.

The two big types of drag are induced drag and parasitic drag.  Induced drag decreases with speed, and parasitic drag increases with speed.  Also related is propeller efficiency, which decreases with speed.  At some speed the combination of parasitic drag and decreased prop efficiency stops a plane from going any faster.

Now lets apply that.  I am in my trusty Jug, and I just dove after a 190A8.  We are both diving to above our top level speed.  He slams it to the deck, and begins deccelerating to his max level speed.  At the same time, I begin a very gentle climb, at just under my max level speed.  After a while we will both be at our max level speeds, but I have several K of altitude I have gained, and in addition my TAS is probably slightly higher due to altitude.  I can then begin a gentle dive to increase my speed above my max level speed, and begin gaining on the bogey.

 

As you can see, at a 3k higher altitude, my TAS will be as much as 15 Mph faster than it would be at sea level.  That is fairly significant and accounts for some of the difference right there.  The TA152 is similar:  

The rest is simply the difference between one plane slowly gaining energy in a very gentle climb, and the other staying static at it's top speed.  Of course, we are also assuming all the other possible factors such as fuel load, WEP state, and that sort of thing which were equal.  Starting energy states also play a big role here.

This is really the opposite case to the one BadBoy is talking about.  In this case we are talking about planes diving above their max level speed, while Badboy is discussing planes accelerating to that speed.  Based on the graphs I've looked at in Shaw's Fighter Combat, there is possible a sweet spot with prop fighters where induced drag may decrease faster than prop efficiency and before parasitic drag starts to ramp up.  We'll see.

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Sean "Lephturn" Conrad - Aces High Chief Trainer

A proud member of the mighty Flying Pigs
http://www.flyingpigs.com

Check out Lephturn's Aerodrome for AH articles and training info!

[miko2d]

 How about this:
 By flying slower you save a lot of energy that would be wasted to air resistance - proportional to square of speed.
 That energy get converted into altitude at a rate proportional to speed. Also the real speed increases with alt as air resistance drops.
 So you end up not much slower then he but with a lot more energy stored as altitude that you can redeem by divng.

 miko

[Vulcan]

You guys are ALL WRONG!!!

Imagine the earth spinning. At all altitudes you will be spinning at x-degrees per second (roughly 0.0041666 degrees per second I believe). As you get further out from the center of the spin your actual speed increases to cover the greater circumferance. Therefore as you were flying higher you were in fact flying fast due to the rotational affects of the earth.

Be warned this does not work if you fly from east to west, west to east only.

Anyone who tries to deny this theory is a flat-earther and will be sentenced to flying a 202 for 1 tour!