Why still no dive acceleration difference?

[FC99]

Originally Posted by BlackBerry

When P51 dives to 4500 m=15000ft altitude, and reaches 640km/h=400 mph IAS,

Why 400mph IAS ? Why not any other number?

Unfotunatly, sonic speed at 4500m altitude is 322m/s, that is to say, the tip of airscew is 1 mach. There is no mach number "concept" in il2's model at all, how can I believe that il2 simulates 1 Mach aerodynamics very well?

Prop planes can't break sonic barrier so it's not that important for Il2 to have highly detailed Mach model.

Tempest could dive to 450 mph IAS below 20000ft, aha, tempest's big rotol 14-ft airscrew, 3800rpm, 450mph IAS, the tip of rotol must be supersonic, so is P51's hamilton, thus the efficiency curves of their airscrews play an important role when they dive to high speed.

Yes it does.

Why tempest outdives p51? For more efficiency airscew @ supersonic? Maybe. For much more heavier fuselage? Probably.

It does? Maybe, depends which models you take for comparison .

All in all, il2's model is lack of supersonic simulation, that's why we couldn't experience what tempest/p51 should be. That's why tempest couldn't outdive dora easily in game.

It should out dive Dora easily, why ?

[BlackBerry]

Why 400mph IAS ? Why not any other number?

It's very common to dive to 400-450MPH IAS for WWII late aircrafts such as P51, P47,Tempest, fw190, etc.

Prop planes can't break sonic barrier so it's not that important for Il2 to have highly detailed Mach model.

Prop planes can't break sonic barrier, but Prop planes' propeller CAN often break sonic barrier in a dive, it's an unfortunate fact for il2.

As early as 1904 when Wright brothers made the first a/c, they knew both airscrew and wing are "same thing".

The twisted airfoil (aerofoil) shape of modern aircraft propellers was pioneered by the Wright brothers. They realised that a propeller is essentially the same as a wing, and were able to use data from their earlier wind tunnel experiments on wings. They also realised that the angle of attack of the blades needed to vary along the length of the blade, thus it was necessary to introduce a twist along the length of the blades. Their original propeller blades were only about 5% less efficient than the modern equivalent, some 100 years later.[2]

http://en.wikipedia.org/wiki/Propeller_(aircraft)

Their original propeller blades were only about 5% less efficient than the modern equivalent, some 100 years later.........


That conclusion is based on low Mach data, for supersonic airscrew, the story is totally diefferent.


In my opinion, the airscrew theory/simulation is the weakness of il2's FM.

It does? Maybe, depends which models you take for comparison .

Tempest MKV 9lbs boost outdives P51B(Mustang III) 18lbs boost.

Dive
For the same reasons as the zoom climb, the Tempest pulls ahead. As the speed is increased it does so more rapidly. The fact is it has the best acceleration in the dive yet seen at this Unit.

http://www.hawkertempest.se/TacticalTrials.htm

Speed and acceleration in the dive is an essential quality to a successful fighter, but a decisive conclusion on the order of superiority is largely dependant on throttle settings, and the maximum speed in straight and level flight of the individual aircraft. Here again, however, by carrying out a number of tests under different conditions, it is reasonable to assume that the Meteor is well ahead of its rivals, followed by the Tempest, Thunderbolt, Mustang and Spitfire in that order.

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

[MadBlaster]

if you simply want to test 'drag' without digging into the code, I think it better to do it with the engine off (i.e., no thrust test).

- go into fmb and set your spawn kph to zero and start a track in cockpit view.

- spawn your plane say 5000 meters and leave the engine off.

- close your rads, neutral your trims, set you prop pitch to 100%.

-push nose into 90 degree vertical.

-end the track when your plane hits the beach at zero alt.

-go back and look at track. look at speedometer at say 20 second mark per track time. (e.g., speed says 400 kph at 20 seconds for this plane)

-repeat with another plane and compare results.

- For the thrust piece, you can use devicelink to get an idea. There is an acceleration parameter that can be graphed/logged. You can see the effect of adjusting throttle and prop pitch. Prop pitch changes and its effect on acceleration is modeled. The csp may be slower to change blade angle than the vdms. At least, that's how it feels like to me. The fw vdm has a torque limiter. I think p factor is also modeled. You can produce de-celeration by adjusting blade angle, according to devicelink.

[BlackBerry]

Crumpp, your very good information.

Especially this one, P47d4 vs fw190a5? a6?

I bet that il2 4.11m can't simulate this.

111.JPG

(C)

(1) 10000 fett to 3000 feet, starting at 250 m.p.h., diving at angle of 65 degree with constant throttle setting. The FW-190 pulled away rapidly at the beginning but the P-47 passed it at 3000 ft with a much greater speed and had a decidedly better angle of pull out.

There are some interesting records:

1) bf109g6as initially outdives spitfire IX LF, but spitfire overtakes 109 as speed building up.

2)fw190a5 initially outdives p47d, but p47d overtakes fw190a5 as speed building up.

3)Tempest and 109G's initial dive acceleration are roughly same, but Tempest outdives 109G easily as speed building up.


When speed building up, what happens to P47/P51/Tempest? There airscrew tips reach/break sonic barrier??? howabout 109/190's airscrew?

If Daidalos Team solve this "supersonic" issue, we''ll appreciate that.