Why still no dive acceleration difference?

[FC99]

Originally Posted by mayshine

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please show your link of the documentation or so

Is it a memior or serious testing documentation?

I have docs showing the diving difference between different aircrafts

TAIC is very serious, have you read what I wrote about it? Report that deal with A6M5 and P-38,P-51 and P-47 is TAIC report No 38. A6M5 was tested against some Navy planes too,F6F-5, F4U-1D and FM-2. Results are published as TAIC Report No 17.

So far you didn't provided any evidence that would suggest that there is something fundamentally wrong with the game. IIRC Your picture that shows dives is from the post war magazine article.

And you will be hard pressed to find any RL test with planes diving at 90 deg straight into the ground or any 90 deg diving test for that matter, ~45 deg maximum angle during the dive is more typical.

[mayshine]

Originally Posted by FC99

TAIC is very serious, have you read what I wrote about it? Report that deal with A6M5 and P-38,P-51 and P-47 is TAIC report No 38. A6M5 was tested against some Navy planes too,F6F-5, F4U-1D and FM-2. Results are published as TAIC Report No 17.

So far you didn't provided any evidence that would suggest that there is something fundamentally wrong with the game. IIRC Your picture that shows dives is from the post war magazine article.

And you will be hard pressed to find any RL test with planes diving at 90 deg straight into the ground or any 90 deg diving test for that matter, ~45 deg maximum angle during the dive is more typical.

would you please show me the link or so, I am new here

I am not here to attack someone

acctually I will be happy if I am proved wrong coz I will not have to be
plaged by this issue anymore and can fully enjoy the Il2

However, thru my/our calculation, things are different with those shown
in Il2

acutually, I do not believe the 45 degree dive is similar to 90 degree seriously

and this is the the blank point we are trying to figure out.

Fw 190 defence action will always start with a split s followed by a certain period of almost 90 degree dive

so the veticle dive has it's meaning

[mayshine]

letme show you some clue here

with the speed increased, the back-drag force will increase pronouncely
due to 1, deformation , 2, propeller pitch, 3, propeller tip speed,4, air wave darging force.

with this backward force increased largely.

the heavier aircraft should prevail in the diving.

roughly it is the result I got, and I am quite comfident it is meaningful
and to some extence correct.

[BlackBerry]

Originally Posted by FC99

TAIC is very serious, have you read what I wrote about it? Report that deal with A6M5 and P-38,P-51 and P-47 is TAIC report No 38. A6M5 was tested against some Navy planes too,F6F-5, F4U-1D and FM-2. Results are published as TAIC Report No 17.

So far you didn't provided any evidence that would suggest that there is something fundamentally wrong with the game. IIRC Your picture that shows dives is from the post war magazine article.

And you will be hard pressed to find any RL test with planes diving at 90 deg straight into the ground or any 90 deg diving test for that matter, ~45 deg maximum angle during the dive is more typical.

1)FC99, 30 degree dive is very different from 60 degree dive,leave alone 90 vertival.

http://www.wwiiaircraftperformance.o...e52-taic38.pdf

P51D and zeke，@10000ft，begin dive at 200MPH（IAS），after 27s， reach 325IAS ，P51D is 200 yards ahead of zeke。

This test is probably a shallow dive(30 degree), in my opinion, if dive in 45-60 degree, P51D will get much more advantage. So we need more data on 45 degree dive.


2)

http://www.wwiiaircraftperformance.org/sl-wade.html

Efficient streamlining and maximum speed both influence the dive, although a jet propelled aircraft will invariably have the advantage, particularly at the higher speeds, when the conventional fighter is progressively more handicapped by airscrew drag, and the accessory protuberances common to all conventionally powered fighters.

As speed building up, the drag force of airscrew increases sharply because the tip of airscrew is approvching sonic.

Does il2 model this increasing drag of propeller? Does il2 model enginee exhaust gas boost at high speed?

3) http://www.spitfireperformance.com/spit9v109g.html

... I had the throttle open and I rolled over and headed on a course to cut the angle toward the 109s, which had separated a little. I wound on nose-heavy trim so essential to keep the aircraft in a high-speed dive. The Spit responded eagerly as I dove more steeply than the 109s, with Red Two and Three no doubt following, although I could not see them. The controls got very heavy as the airspeed needle moved far right at 480 mph. (Corrected for altitude, true airspeed approached 600 mph.) I could see that I was gaining on the nearest Me 109. That was something new. We were already half-way to Sicily; that was no problem. We knew from years of experience, dating back to the boys who had been in the Battle of Britain, that the 109 with its slim thirty-two foot wing was initially faster in a dive than we were. But we accepted that compromise happily in exchange for our broad superior-lift wing with its better climb and turn. One couldn't have it both ways. In any case, I was closing on this Me 109, which I recognised as a G. Perhaps he wasn't using full throttle.

We were down to 5,000 feet and our dive had become quite shallow. I could see the Sicilian coast a few miles ahead. Now I was within range at 300 yards, and I let him have a good squirt. The first strikes were on the port radiator from which white smoke poured, indicating a glycol coolant leak. I knew I had him before the engine broke out in heavy black smoke. (Bf 109 G-4 "Black 14" of 2(H)/14, flown by Leutnant Friedrich Zander, shot down 10 June 1943)

In il2, Does bf109 outdive spitfire at initial stage of dive?

[JtD]

Originally Posted by BlackBerry

This test is probably a shallow dive(30 degree), in my opinion, if dive in 45-60 degree, P51D will get much more advantage.

Accelerating from 200 to 325 the difference will be mostly the same, if diving for 27 s the difference will be bigger. However, in a steeper dive the limiting speed of 325 IAS will be reached sooner, therefore you'll be diving for less than 27 s, and separation will be smaller.

[FC99]

Originally Posted by BlackBerry

1)FC99, 30 degree dive is very different from 60 degree dive,leave alone 90 vertival.

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.

set g=10, m = 10 , back force = 50

plane mass = 2m
second plane mass = 1m

F=ma

a1: a2
= (2m*g-backforce)/2m : (m*g-backforce)/m
=150/20:50/10
=7.5:5

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.

Acceleration

FW
(4100*10-4000)/(4100)=9,02

La5

(3300*10-4000)/(3300)=8,79

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

page 3-4


There is a "zoom"(should be nearly 90 degree upwards) test about P51D and Zeke with same cruising speed and altitude, side by side.


If il2-4.11m perfectly reproduce this "zoom" record, this thread's "boom" discuss can be closed.

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.

[SaQSoN]

Originally Posted by mayshine

yes, should have been more pronounced

We all here agree, that real life rarely meets our expectations. Particularly, when someone thinks, he is wa-a-ay much better pilot, then he actually is.

[BadAim]

Originally Posted by SaQSoN

We all here agree, that real life rarely meets our expectations. Particularly, when someone thinks, he is wa-a-ay much better pilot, then he actually is.

LOL, what he said.....a man's got to know his limitations.

[Treetop64]

Originally Posted by mayshine

yes, should have been more pronounced

According to what? Your own personal expectations?

[zxwings]

Originally Posted by FC99

In TAIC test between the Zero and P-47 when they started the dive from 10000ft at 220MPH IAS and dived until Zero reached maximum allowed speed (325MPH IAS). It took 30 seconds for that and the P-47 had 100 yards advantage over Zero.

Disapointing, isn't it?

Diving vertically down? Or at what angle to the ground?