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XyZspineZyX
09-25-2003, 09:37 PM
I could be wrong, but since when speedmeter in planes show IAS (speed over ground). Well i think that Pitot's pipe connected 2 speedmeter can't show IAS (it can't i'm glider pilot).
Then i was thinking about flying 109f2 and checking his maximum speed. I was flying on 1km. and checking my speed.
Well IAS (speed over round) should be lower than TAS. When i look at speedmeter and at speed bar i saw (for example) 400km/h... then i've pressed ctrl+f1 and check speed on the other speedmeter, where it was much figher. I realized that something wrong here, and started to think that speedmeter in plane shows IAS here?
Can anyone can light me on?
Is there any mistake of my thinking
Anyway i'm sure of one thing that speedmeter in plane should show speed in air, not over ground. And it looks like it shows speed over ground. hmm...

XyZspineZyX
09-25-2003, 09:37 PM
I could be wrong, but since when speedmeter in planes show IAS (speed over ground). Well i think that Pitot's pipe connected 2 speedmeter can't show IAS (it can't i'm glider pilot).
Then i was thinking about flying 109f2 and checking his maximum speed. I was flying on 1km. and checking my speed.
Well IAS (speed over round) should be lower than TAS. When i look at speedmeter and at speed bar i saw (for example) 400km/h... then i've pressed ctrl+f1 and check speed on the other speedmeter, where it was much figher. I realized that something wrong here, and started to think that speedmeter in plane shows IAS here?
Can anyone can light me on?
Is there any mistake of my thinking
Anyway i'm sure of one thing that speedmeter in plane should show speed in air, not over ground. And it looks like it shows speed over ground. hmm...

XyZspineZyX
09-26-2003, 01:04 AM
I think you have the definitions backward.

TAS: True air speed. Actual speed relative to the ground.

IAS: Indicated air speed. Value given by pressure difference between pitot tube and static port. IAS will always be lower than TAS, and the difference will be greater the higher your altitude.

XyZspineZyX
09-26-2003, 12:25 PM
So as i said IAS should be shown in plane and should be much bigger than TAS.
In FB speed shows in plane is smaller than speed show when u press ctrl+f1.
Everything's fine?

XyZspineZyX
09-26-2003, 04:08 PM
kostek wrote:
- So as i said IAS should be shown in plane and should
- be much bigger than TAS.
- In FB speed shows in plane is smaller than speed
- show when u press ctrl+f1.
- Everything's fine?
-
-

No no no. IAS will always be less than TAS. In the game it's correct.

XyZspineZyX
09-27-2003, 02:11 PM
I posted this before also about the IAS,TAS speeds.

If the ctrl/f1 no cockpit view is reading TAS and the speed bar and in-plane A/S indicater is reading IAS then, the first thing wrong is IAS and TAS are the same at sea level not different from each other, and if you look at the speeds on a winter map, they are opposite from the summer maps.

Winter map you will see ctrl/f1 view speeds lower then in plane or speed bar.

Summer map you will see ctrl/f1 view speeds higher then in plane or speed bar.

And TAS is never less then IAS.

~S~

XyZspineZyX
09-27-2003, 06:43 PM
Cooler07 wrote:
- I posted this before also about the IAS,TAS speeds.
-
- If the ctrl/f1 no cockpit view is reading TAS and
- the speed bar and in-plane A/S indicater is reading
- IAS then, the first thing wrong is IAS and TAS are
- the same at sea level not different from each other,
- and if you look at the speeds on a winter map, they
- are opposite from the summer maps.
-
- Winter map you will see ctrl/f1 view speeds lower
- then in plane or speed bar.
-
- Summer map you will see ctrl/f1 view speeds higher
- then in plane or speed bar.
-
- And TAS is never less then IAS.
-
- ~S~
-
-

It should be very close to the same at sea level, and yes this is correct. It's only as you go up that they will start to differ, but at sea level, they should be very very close, given no wind. You can't change the game's in flight temperture, so it's assumed standard tempature.

I hate to tell you, but the game is correct.

TAS never less than IAS? I sure hope you never get a headwind. Your wrong about that also.

Sorry buddy, do some research.

XyZspineZyX
09-27-2003, 07:31 PM
LOL Right!!!! I think you need to do the looking, 14 years on the line and 3 type ratings.

You can have any headwind you want that will not change TAS to below IAS. Headwind changes your GROUND SPEED bro not IAS.

There might be some difference with TAS/IAS at sea level like 2 to 3 knots not 15 to 25 kph like I tested on winter and summer maps.

And TAS is never below IAS at sea level! Save for some instrument error thats about the only way!!!

Also the game is wrong if the nocockpit view A/S gauge is reading TAS and the speed bar is reading IAS, because if you test (no wind) any plane on winter and summer maps you will see that they are reading differently from each other.

On winter maps the speed bar is showing faster then A/S gauge crtl/f1 view and in summer maps its reading lower.


~S~

As posted before::

The test 4 A/C all with Rad closed, 110% throttle,100% Fuel and default loadout.

WS a/c 100% prop,100% mixture,supercharger stage 1.
LW a/c auto prop,wep.

On-line Summer and Winter map,(WIND TURNED OFF) takeoff from far southwest base fly heading 250. Speed bar altitude 0 sea level,no cockpit dial altitude. 10 to 15 meters.

Speed reading from speedbar=(SB)
Speed readings from airspeed gauge=(ASG),(no cockpit view)
All speed (kph) +.- 3kph


_______Winter Map______Summer Map

109K_____SG=558_________ASG=580
_________SB=570__________SB=570

La7(3x)__ASG=582________ASG=600
_________AB=600__________SB=590

Yak-3___ASG=543_________ASG=562
_________SB=560__________SB=550

190D-45_ASG=578_________ASG=595
_________SB=600__________SB=580


This test was just to get a flat out speed run all A/C flown for 5 minute (109K for about 2.5 then overheat) to get the top sea level speed.

Don`t know about anyone else but the speeds look a little different for the Summer and Winter Maps.

~S~

XyZspineZyX
09-27-2003, 07:58 PM
5 years on the line and 2 type ratings later, I do think that TAS CAN be lower than IAS. e.g. if the density altitude is below standard. >Which is very well possible on a cold winters day. Take that old E6B out of your flightbag and check it out ;-)

XyZspineZyX
09-27-2003, 08:50 PM
IAS is only equal to TAS at sealevel on a standard day. TAS can be either higher or lower than IAS at sealevel depending on the actual atmospheric conditions. In IL-2, different maps model different ambient conditions and therefore this influence the air speed conversions. IAS can actually be significantly higher (a few percent) than TAS at sealevel in extreme environmental conditions.

Also, as already mentioned, neither TAS nor IAS represent ground speed. TAS is only equal to ground speed if there is no wind. In short:

IAS (Indicated Air Speed) - the value you read on your airspeed indicator, which is a reflection of the difference between the dynamic pressure and static pressure measured by the pitot probe. The IAS you read on the instrument actually tells you how fast you would have been flying (TAS) if your airspeed indicator was reading the same value, was calibrated and installed correctly, and if you were flying at sealevel on a standard atmospheric day.

CAS (Calibrated Air Speed) - the IAS corrected for installation and instrument error.

EAS (Equivalent Air Speed) - the CAS corrected for compressibility. This also takes temperature into account.

TAS (True Air Speed) - the speed you are actually flying relative to the air. This can be calculated from EAS by dividing by the square root of the density ratio. Normally EAS is not calculated though, and TAS is calculated directly from CAS using a formula that includes temperature ratio.

Ground Speed - the speed of the aircraft relative to the ground. This is equal to TAS only if there is no wind. Generally you would need something such as GPS or an equivalent to measure ground speed.

XyZspineZyX
09-28-2003, 02:56 AM
Cooler07 wrote:
- LOL Right!!!! I think you need to do the looking, 14
- years on the line and 3 type ratings.


Crud, I got speeds mixed up. I was thinking ground speed, not air speed. Yipes, I do apologize. Whether it really can happen is anybody's guess, certainly mine.

BTW, I've got a few type ratings of my own. Type ratings don't mean you know airspeeds. I know someone who has his Multi-Engine Commercial rating, who confused two airspeed types when we were talking.

Message Edited on 09/27/0309:00PM by waterinthefuel

XyZspineZyX
09-29-2003, 05:22 AM
Hey my apology to waterinthefuel didn`t mean to come across that way and also to all others here for my mistake, it is possible to have TAS below IAS.

Normally never worry about because we don`t fly at sea level and in looking at it you have to have some pretty extreme circumstances to get them, but it can happen.

Also as far as the game goes getting the TAS and IAS readings I don`t think its modeled in for instrument errors and pressure differences. To get 20 to 30 off on speeds the temps have to be around -40 to -70c which is possible in real life just don`t think there is much flying in it, damn cold for sure!

So again my apologies to all for my mistake I think I`ll stay with the alt. Sure em glad after this long I`m still learning.

~S~ All have fun!