P40 Drag Ratio

[Schweinefliege]

I'm just curious if anybody is knowledgeable and can explain something to me, I understand that the faster an aircraft goes, the more drag there is, that's like fundamental in aerodynamics right? More lift, more speed = more drag?

 

Maybe I'm crazy, maybe its pitot tube lag, but if I go full throttle, IAS seems to accelerate pretty rapidly, with a steady decrease in acceleration up to 150 IAS. Then the indicator just stops like it hit a muddy water, and then continues much slower in acceleration, flying horizontal it takes forever to reach top speed. I just feel that it should be able to reach 250 knots much quicker in the horizontal than it does, especially with full power, but maybe the drag coefficient really is that bad, not sure.

 

I have the same feeling towards dives, everybody brags how this thing can dive like a banshee, but I feel like when I try to dive that I'm a featherweight, takes forever to reach the high speed dive that I am looking for, at least for a 8 ton aircraft in my mind.

 

Not a professional aerospace guy or anything, but just curious if anyone has any info or suggestions regarding the slow rate of acceleration past 150 - 200 IAS with this bird?

[Ehret]

The P40 is a heavy frame with, as in game, very strict engine boost limits - that's why she doesn't accelerate quickly. When diving the initial acceleration may be slow, too, but keep going and eventually the Kittyhawk will outrun everything, except the FW 190.

[Schweinefliege]

Right, must've been diving wrong against a 109 yesterday then, but I'm talking about if I choose to use that 30 seconds full boost, or even the 45.5 for a minute or two at 3000rpm, I just feel like it creeps to even 220 knots regardless from 150 ias. Maybe I'm wrong and it drags like crazy, but I feel like up to 220 to 250 knots should be quicker to obtain at high boost and rpm, not much of a difference between standard and combat mode or wep mode. And still a little baffled at the sudden decrease in acceleration at 150 ias unless that is pitot lag or something.

[unreasonable]

There are no pitot errors modeled in the game.  The way I would think about this is to look at a speed/drag curve something like this: 

 

https://www.theairlinepilots.com/forum/viewtopic.php?t=369

 

Point being that as you accelerate in level flight from a very low speed total drag actually first reduces, then increases (exponentially?) at higher speeds, so it makes sense that acceleration is reduced past this point of minimum drag. Not only is the drag increasing for every extra mph you add over this minimum drag point, but the thrust you have left over after overcoming the drag will be continuously reducing at this point. So it is inevitable that acceleration must slow to zero as you approach maximum speed.

[TP_Jacko]

Just wondering if you have set the P40 to show mph on kmh

[Schweinefliege]

Yes, the gauge is reading IAS in mph.

 

That makes sense about the drag, I understand it would increase and the thrust won't be able to overcome it over time, it's just kinda weird to have such a dramatic acceleration difference change right around 150 mph or so, I just thought it would be a smoother exponential curve like your talking about, because it seems like its exponential with a sharp decrease in acceleration, or increase in drag, at 150 mph, wish I knew how to make these graphs that I see people make sometimes. I can visually see the needle just suddenly slow down it's acceleration like it hit a wall. Just odd to me.

[Ehret]

You must account for the loss of propeller efficiency with increasing IAS. The velocity gauge in the P40 isn't fully linear, too.

[=LD=Hethwill]

I tend to lower pitch the faster I go, especially on the P40 in those shallow dives and picking up speed. Seems to work.

[Schweinefliege]

Well I'm dumb, if you look at the gauge of the airspeed indicator, the notches get smaller after 150 ias, so of course it's going to slow down to represent the same acceleration because now ten knots more is like a 1 degree turn rather than the 12 degrees for ten knots before 150 knots *palms face*