TAS at sea level too low

True Air Speed. Tacview Agrees. Shows the same speed in MPH converted from knots since that is what I have my Tacview set to.

Then explain to me how that can be when in the aircraft that have instruments that show TAS it is often very different compared to F2 and in the A-10C GS is always off by 2kn compared to F2 no matter what? Did you even bother to look at the pics I posted?

Same in the MiG-21. If I fly into the Wind TAS is higher than what is shown in F2, if I fly with the wind it's lower. So yep, I'd say it's GS

Or F2 doesn't correct for wind?

Then explain to me how that can be when in the aircraft that have instruments that show TAS it is often very different compared to F2 and in the A-10C GS is always off by 2kn compared to F2 no matter what? Did you even bother to look at the pics I posted?

 

Same in the MiG-21. If I fly into the Wind TAS is higher than what is shown in F2, if I fly with the wind it's lower. So yep, I'd say it's GS

 

Or F2 doesn't correct for wind?

I looked at the pictures you posted. Are you looking at mine? A Plane going straight down would have a GS of zero (or near as makes no difference). Has it occured to you that either there is an error in the A-10s instrumentation in game or that you are mis-reading the guage somehow?

It hardly matters. We now have proof that it is True Air Speed, end of story. Unless you think it switches from GS in horizontal flight to TAS when going straight down just to play tricks on you......

Tacview gives me the same speed......you think they are both lying?

I looked at the pictures you posted. Are you looking at mine? A Plane going straight down would have a GS of zero (or near as makes no difference). Has it occured to you that either there is an error in the A-10s instrumentation in game or that you are mis-reading the guage somehow?

 

 

It hardly matters. We now have proof that it is True Air Speed, end of story. Unless you think it switches from GS in horizontal flight to TAS when going straight down just to play tricks on you......

 

Tacview gives me the same speed......you think they are both lying?

Yes, I did look at your Screenshot and it's a bit puzzling because if it indeed shows TAS something is definitely not right!

The TAS in the A-10C is what I would expect under those conditions (about 900ft, wind coming from the back at around 4-5m/s (not exactly sure what I put there), 220kn IAS, 234GS (according to TAD) so yes, 226TAS sounds about right.

If I fly with the wind, the number in the F2 view goes UP, not DOWN. Exactly what I would expect if it would show GS but the opposite of what I expect if it's TAS.

I fly with wind in my Missions so when I go into F2 I notice these things. This is from memory and I probably wasn't flying exactly with and into the wind but it shows a pattern:

In the MiG at M2.05, 10000m (~33000ft) flying into the wind with wind at 14m/s at 8000m it shows ~1164kn while the TAS in the MiG Cockpit shows ~2200km/h. 2200km/h is about 1187kn. Now, if the wind is coming from the back, the fastest I've noticed was around 1210kn which I do not expect at all if it's TAS.

So I guess what we can take from it is, that at least with wind, F2 is not showing correctly (if it is TAS which your screenshot suggests). I'll look into it some more tomorrow.

Yes, I did look at your Screenshot and it's a bit puzzling because if it indeed shows TAS something is definitely not right!

The TAS in the A-10C is what I would expect under those conditions (about 900ft, wind coming from the back at around 4-5m/s (not exactly sure what I put there), 220kn IAS, 234GS (according to TAD) so yes, 226TAS sounds about right.

 

If I fly with the wind, the number in the F2 view goes UP, not DOWN. Exactly what I would expect if it would show GS but the opposite of what I expect if it's TAS.

 

I fly with wind in my Missions so when I go into F2 I notice these things. This is from memory and I probably wasn't flying exactly with and into the wind but it shows a pattern:

 

In the MiG at M2.05, 10000m (~33000ft) flying into the wind with wind at 14m/s at 8000m it shows ~1164kn while the TAS in the MiG Cockpit shows ~2200km/h. 2200km/h is about 1187kn. Now, if the wind is coming from the back, the fastest I've noticed was around 1210kn which I do not expect at all if it's TAS.

 

So I guess what we can take from it is, that at least with wind, F2 is not showing correctly (if it is TAS which your screenshot suggests). I'll look into it some more tomorrow.

Since wind seems to effect it, which makes it nothing kind of speed then. But its not GS or TAS.

Some aircraft had the pitot tube located in a position where the airflow through it was unusually altered by an unintended source. For example, the P-38's pitot tube was too close to one of the engines, and the propwash was affecting the tube, causing the ASI to display a very incorrect airspeed. Hence calibrated IAS. IIRC, there's a chart in the P-38 handbook with a table for calibration...

Here is the Airspeed Correction Chart for the P-51D-5 from the Pilot's Flight Operating Instructions, 5 April 1944:

Here is another PEC chart for the P-51 dated 15 June 1945:

Maybe F2 view speed readout works different for different modules? Doesn't make sense to me, but hey, discrepancies in P-51 vs A-10 data don't make sense either. I never paid attention to this issue, but I may do some testing with other planes later :).

I seem to recall it having been established that it was purely geometrical speed in the game world - i e the absolute magnitude of the velocity vector, ground referenced.

If that matches your findings here, then that's probably it. If not, I may remember it incorrectly. Find the P-51 vertical dive thread, I think that's where it was discussed at length.

Cheers,

/Fred

Is that why AI 109s out turn me?

I seem to recall it having been established that it was purely geometrical speed in the game world - i e the absolute magnitude of the velocity vector, ground referenced.

 

If that matches your findings here, then that's probably it. If not, I may remember it incorrectly. Find the P-51 vertical dive thread, I think that's where it was discussed at length.

 

Cheers,

/Fred

Now that You said it, I indeed recall something like that mentioned in some ancient thread somewhere here. It ain't "proper" TAS nor GS then. Let's just call it DCSS :D !

Our P51 doesn't work like the real one.

All indications are that max speed is attained at 3K RPM in the real plane. Ours reaches max speed below that. As a matter of fact it seems to go faster and faster the lower the RPM setting, but... As you get further and further below about ~2700RPM you're really taking a large risk in grenading the engine no matter what temperature you keep the coolant and oil at by manually manipulating the cooling tunnels. Or by leaving them on auto for that matter... but I never do. I can manage the engine/oil temperature much better than the auto systems at this point.