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View Full Version : will ever be solved the wrong data from the nocockpit gauges?



raaaid
09-01-2005, 04:19 PM
the no cockpit speed gauge always shows a superior speed than the speedbar

it cant be the wind speed because you cant always have the wind in favour

besides the altitude gauge is useless because it measures hills, is not barometric

i cant believe that after 5 years they still haven fixe this

AFSG_Bulldog
09-01-2005, 04:23 PM
I have never noticed the anomolies you mentioned. Mainly because I never use "wonder women" views. I prefer the confines of the cockpit myself.

LEBillfish
09-01-2005, 05:26 PM
I.A.S. vs. T.A.S.

Now you know everything http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

neural_dream
09-01-2005, 05:33 PM
sure it doesn't measure hills. only the 110g-2 can measure ground. all the rest measure sea level. oh maybe it's different for wonderwoman, like the IAS TAS thing.

NonWonderDog
09-01-2005, 09:14 PM
Wonderwoman shows airspeed TAS and altitude AGL. I don't see why that's a problem.

mredinius
09-01-2005, 11:20 PM
When using the gauges at the bottom of the screen in "wonder woman" view, your gauges indicators may be slightly askew from reality.

mredinius
09-01-2005, 11:21 PM
hmm can't modify a post here........guess I'll be looking like an idiot alot.....

ClnlSandersLite
09-02-2005, 12:18 AM
See my sig to figure out IAS vs TAS

Waldo.Pepper
09-02-2005, 01:10 AM
This is funny on so many levels.

JG53Frankyboy
09-02-2005, 02:54 AM
Originally posted by Waldo.Pepper:
This is funny on so many levels.
oh, yes http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

berg417448
09-02-2005, 07:27 AM
Originally posted by mredinius:
hmm can't modify a post here........guess I'll be looking like an idiot alot.....

umm...yes you can. Edit button is on bottom right of your posts..

mredinius
09-02-2005, 08:55 AM
Originally posted by berg417448:
umm...yes you can. Edit button is on bottom right of your posts..

AHA! See - told ya I'd be looking like an idiot alot.....

Thanks!

Edit : There really is no edit, just adding an edit to make sure I can edit. The edit.

GH_Klingstroem
09-03-2005, 11:40 AM
Too many times I have seen people complaining about how they can not reach the top speeds of their aircraft so I will try to clarify in this post in a simple way how it works.

Indicated airspeed(IAS): This is simply the speed that is indicated on the instrument inside of the aircraft. On the leading edge of most (small) aircraft there is a tube sticking out about 5cm. The purpose of this tube is to give a speed reading to the instrument inside the aircraft. As the aircraft moves forward the air flows over the wings, fuselage and also into this tube. The more air (the faster you go), the more air will flow into the tube and give you a faster indicated speed inside the cockpit. We all know that the higher you go the less dense the air becomes and the lower you go, the more dense the air becomes. It becomes more compressed lower down because the whole atmosphere above is heavy and compresses the air below. Think of the air as amount of air molecules. This means that when you are flying around at low altitude there will be lots of air molecules going into the tube and give u a high indicated airspeed which is great. But say now that you start climbing, things will become different. Up high the amount of air molecules is much less, so there is less air molecules going over the wing and into the tube in the wing and so you will get a lower INDICATED reading(there is also less power for the engine)!! Quite simple actually! We all know what happens when the indicated speed becomes too low! We lose lift and stall! Pretty much the only thing you use indicated speeds are to know when you will stall! You can not really use it for proper navigation at all!

True airspeed (TAS): Most of us have seen this in the game but a lot seem not to understand it. The TAS you cannot read in the cockpit in these planes but is very important for navigation. Now, as I wrote above the air gets thinner and thinner the higher you go. That€s the way things are and we cannot do anything about it, however the formula of lift says states that in order to maintain the same amount of air molecules over the wing,, when there are less of them, is to fly faster. This happens automaticly. We as pilots cannot control it! Even if you read 200knots on the indicated speed gauge at sea level and you now read 200 knots at 20 000 feet, you will go much faster trough the air and therefore also over the ground! Basicly the aircraft has automaticly compensated for the thinner air and is now flying faster through the air in order to keep the same amount of air molecules over the wing, and in the tube! Great isn€t it?! Now this is all well and through tables you can read get your TAS, if the IAS is known and the altitude and the temperature (since the temp also changes the density of the air. Cold air = higher density=heavy. Warm air=lower density=light).
What you see in Cockpit OFF mode n this game is the TAS. You will see as you go higher your TAS will be higher and higher but your IAS will get lower and lower for the above reasons. At sea level TAS and IAS will be the same as the aircraft doesn€t have to compensate for the difference in density. Try it in the game and you will see! The top speeds of aircraft are given in TAS and usually at what alt that top speed is achieved and NOT in IAS!! If there is no wind your TAS will be the speed that you are flying over the ground! Hence you will reach your destination faster if you go high! If there is wind the speed over the ground is different and I will explain that below.

Ground speed (GS): Ok to continue with what I wrote above. Say now that you are cruising around in your P-51 at 20 000 feet and the you want you IAS at 200knots. Knowing that at this altitude there are less air molecules per area so that your P51automatically compensating for this by flying faster to get the same IAS. Actually you and your P-51 are flying at 273 knots, through the air to give you enough air molecules to give you a reading of 200 knots on the gauge!! This is in NO WIND condition!! I will explain this now with an example



Example 1: NO WIND!!

We are flying from west to east (90 degrees on the compass) at 200 knots IAS at 20 000 feet (temp -20C) in these conditions we are going through the air as stated above at 273 knots TAS and since there is no wind to push us around this day, this is also our speed over the ground! Easy!

Example 2: now with 20 knots tailwind.

This means that we have wind helping us to get to destination. Ok we are still flying from west to east but now we also have 20 knots of wind from the west pushing us towards destination. What this does is to decrease our TAS. This happen because TAS is the speed of the air over the wing from ahead. Now there is 20 knots of wind from behind working in the opposite direction to the airflow over the wing so you TAS will decrease by 20 knots but your ground speed will increase by 20 knots. So if you did 273 knots TAS and 273 knots over the ground in NO WIND conditions, you will now fly 293 knots over the ground but your TAS is only 253 knots. Imagine a windy day, when you run with the wind there is almost no wind hitting your face but you run faster,(low TAS but high groundspeed in this case), but if you turn around and running towards the wind much more wind will hit your face(High TAS but you run slower over the ground ). Same principle! You can control nothing of this as a pilot and usually you are not even aware of it. On the GPS today you can see the speed over the ground and therefore work out the TAS if you know the wind speed and direction, IAS and the temp.

Example 3: now with 20knots headwind.

We are still flying our P-51 east at 200 knots IAS at 20 00 feet and on the thermometer we can see its still -20C outside. On todays forecast they anticipated 20knots of wind from east to west. This is a headwind working against us, pushing us back preventing us to get to destination in time! Now our TAS up here was 273 knots but know we have another 20 knots of air flowing over the wind so the true speed of the air going over the wind is actually 293 knots, but our speed over the ground has slowed down to 253 k nots!

From this we can see that TAS and groundspeed are only the same if there is no wind that day! There is almost always wind up there so very seldom is the TAS and the GS the same!
In this game however there is no wind modelled as far as I know so the speed you read in NO cockpit mode is also the speed you are flying over the ground!

As you can see IAS is only used as a way of knowing how many air molecules that are flowing over the wing producing lift. Its good to know for take off and climb out and for landing. But for actual navigation it has no purpose!

One more for you. At sea level with no wind at all, your IAS will the same as your TAS and since there is no wind it will also be your groundspeed! Hope this helps some of us!
Cheers!

shinden1974
09-03-2005, 12:00 PM
yeah GH_Klingstream, I spent 30 minutes writing up a post like yours before I realized that the topic poster was raaaaiiiiiidddddd...

I erased it.

Aeronautico
09-03-2005, 12:22 PM
Originally posted by shinden1974:
yeah GH_Klingstream, I spent 30 minutes writing up a post like yours before I realized that the topic poster was raaaaiiiiiidddddd...

I erased it.

http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Somebody recognises the fisher eventually.

neural_dream
09-03-2005, 01:38 PM
d@mn, just noticed. lol. It really was funny on many levels.

GH_Klingstroem
09-03-2005, 03:11 PM
hehe never seen his posts before. Luckily I wrote this post a few weeks ago for another thread and still had it on my harddrive. so no 30mins spent here only a few secs... http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

shinden1974
09-03-2005, 06:27 PM
I had a few corrections to the post...since I work on these instruments for a living...however it's really unconsequential...

The IAS uses more than just the Pitot tube (Pt), it uses the Static port (Ps used for altitude indication, most aircraft will use a second static port and seperate the 2 systems) as well, the pressure differential between the two is your indicated airspeed. Because temperature and barometric conditions affect all three instruments, they won't exactly be true airspeed on the ground with no wind...but close enough that you probably woudn't care!

You're probably already aware of all this anyhow.

GH_Klingstroem
09-04-2005, 04:11 PM
yup Shinden, very true. I was just trying to keep it as simple as possible...
cheers!

ruf9ii
09-04-2005, 09:38 PM
is this a troll?

because seriously...i'm not sure why all you guys responded at all.

Tully__
09-05-2005, 02:29 AM
Originally posted by raaaid:
i cant believe that after 5 years they still haven fixe this

I can't believe that after five years you haven't seen the explanation for the difference on these forums before http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif