Why still no dive acceleration difference?

[BlackBerry]

Originally Posted by FC99

Not really, as JtD already pointed, time is big factor here. If you dive vertically you will reach max allowed speed very fast and you will have not enough time to build big separation. And remember, when we are talking about planes like P-51 or P-47 and A6M5 we are talking about polar opposites of WWII fighter world.

That's basically the biggest difference you can expect and it is still not some huge separation some are wishing for.

Let's go back to mayshine's calculation for a moment.

Now let's put some real numbers for mass. I'll use FW190A5 and La5 values for mass. For now we will assume that drag(backforce) is the same although drag is somewhat higher for FW, I'll use drag = 4000 for both planes in time =0.

How much difference you can expect if they started the vertical dive from 2000m to the ground with starting speed = 260 Kmh?


Zoom is not necessarily 90 deg and in case of WWII fighters 90 deg zooms are mostly useless due to low power/weight ratio.

But again, difference is very small just 300 ft(~100m) from cruise flight up to 500ft after the zoom from dive. Considering that everything under 500m (~1600ft) is shooting distance for most Il2 players it is not enough to just put your plane into dive or zoom and expect that will solve all of your problems.

Backforce increases sharply as speed build up. The heavier a/c is, the more ability of retaining high speed which is above a/c's maximum level speed.


In P51-zeke's test, they just did a shallow dive and then zoomed up. The zoom's beginning speed must be lower than 325PMH IAS.


At first, they zoomed up from cruising speed,that was 210MPH IAS=250MPH TAS, when P51d reach 130MPH=150MPH TAS, zeke was 90m lower. So how much kinetic energy was spent to get altitude?

0.5(250^2-150^2)= 20000

If they begin from 325MPH IAS=389MPH TAS

0.5(389^2-150^2)= 64410

We assume that there is a linear relationship between "kinetic energy" and P51D's zoom advantge to "damaged" zeke52.

So this time, p51d should be 3.22*90=290metres higher.


That is to say, when p51d @325MPH IAS@10000ft, and find a (lightly damaged) zeke on his 6 with same altitude and speed. And the distant between them are 450 metres. P51D may try a zoom, and will probably (450+290)=740m higher than zeke when p51d's speed drops to130 MPH IAS.

Surely 740m is enough for avioding being hit by zeke's cannon.

Forthermore, let's assume zeke could bear 450 IAS@10000ft, if they zoom from 450MPH IAS=539MPH TAS

0.5(539^2-150^2)= 134010=6.7 times of so called small "90m",that is 603 metres higher.

Surprising？Somebody will say zeke was underpowered and lightly damaged， I admit it， however， our caculating basis is on medium-low speed data, merely 210MPH to 130MPH IAS, it seems that p51d's zoom advantage will be more remarkable in high speed zooming, given by same amount of kinetic energy consumed.

Perhaps, p51d will gain sth.300meters advantage over 109 by starting a high speed (450MPH IAS)zoom, who knows? You can not simply deny that possibility.