Altitude Discrepancy??????????

[fiddlinjim]

The altitude as shown on the HUD and as shown on FW190 instrument panel is different by as much as 800M and I am never sure which is accurate.

I have tried the "Altimeter at Nearest Base"  command but it doesn't affect the difference significantly.

Has anyone encountered or solved this issue?

Jim

[Y-29.Silky]

Same goes for bomb sights. The bomb sight is a good 5-800m's off vs what's shown on the instrument panel.

Edited January 6, 2015 by Silky

[=69.GIAP=MYATA]

I think bombsight shows altitude above sealevel, gauge and  hud show altitude above ground.

[Willy__]

I think its related to the air temperature/air pressure at high altitutes and how the altitude was measured by the instruments, since we have some extreme temps, and the pressure varies with it. I'm not sure, maybe someone who knows can explain better.

 

I guess thats also the same reason theres the IAS (indicate air speed) and TAS (true air speed). The discrepancy gets bigger as you get higher.

Edited January 6, 2015 by istruba

[fiddlinjim]

One thing I have noticed is that when you take off from a runway in the missions, the altitude readings of the HUD and the instrument panel agree with only a small variation.

During the campaigns with an air start however, they are off significantly.

The planes cannot detect altitude above ground as this would require functional airborne radar.

Jim

[Sokol1]

Easy fix, turn of that... "HUD".

[VBF-12_Stick-95]

Not necessarily a HUD thing.  In the Pe-2 there is a difference between the cockpit altimeter and the bombsite altimeter, cockpit being higher.  The cockpit will show 4,000 meters and the bombsite will show something like 3,600 meters.  I use the bombsite altitude but have not heard the reason for the difference.  In level flight the bombsite altimeter does not change when going over various terrain.

 

According to Google Earth, the terrain around Stalingrad runs from ~150 ft to ~450 ft above sea level.

[TG-55Panthercules]

Not necessarily a HUD thing.  In the Pe-2 there is a difference between the cockpit altimeter and the bombsite altimeter, cockpit being higher.  The cockpit will show 4,000 meters and the bombsite will show something like 3,600 meters.  I use the bombsite altitude but have not heard the reason for the difference.  In level flight the bombsite altimeter does not change when going over various terrain.

 

According to Google Earth, the terrain around Stalingrad runs from ~150 ft to ~450 ft above sea level.

 

Well, I'm just speculating as I don't know either how it was done IRL or how they've done it in BoS, but it would make sense to me that (a) the cockpit gauge would show altitude above sea level (because, if I understand correctly, things like mixture, supercharger settings, etc. that have to do with air pressure depend on height above sea level, not above ground level), whereas (b) the bombsight gauge would show (estimated/projected) altitude above ground level, because the bombing calculations the bombsight is utilizing would depend on height above ground rather than height above sea level.  That would seem to explain why there would be a difference between the two gauges, though it doesn't explain why the gauge difference in the game would be about 1,200 feet if the terrain around Stalingrad is only about 150-450 feet above sea level.

 

I would not expect the bombsight gauge to change (automatically, at least) when flying over different terrain, as that would seem to require some sort of functioning ground-scanning radar - instead, I would assume that the bombsight gauge would be manually set/calibrated (probably before takeoff but possibly by the bombardier in flight in case the target changes) based on the known data about the target's ground level altitude above sea level.  I don't think this setting is alterable by the player in BoS, from what I've seen so far, but if the terrain in the area only varies by about 300 feet in height I would assume that the devs would just pick some compromise/average number near the middle as the default offset for the bombsight gauges, as that would seem close enough for the level of precision needed in the game.

[VBF-12_Stick-95]

I think indirectly Pantherculers you hit the nail on the head, i.e., everyone is guessing why there is a difference.  Sure would be nice to know what the a difference is.

 

At 4,000 meters the difference in the two altimeters is about 400 meters or 1300 feet.  As stated above the difference in the terrain above sea level in that area is only about 450 ft.  That is quite a variance.

 

I assume the bombsite altimeter to be in meters ASL.  I then adjust the site for approximate target ground level (not sure this is necessary but what the hell).  Maybe something else will be coming in an update.

 

I am not an expert but I'm pretty sure there was only one altitude reading available (same reading as the cockpit) in the aircraft when bombing.  The target level was then taken into account by the bombardier.  At the moment I am hitting my targets so I am happy. 

[StG2_Manfred]

I don't know whether or not it matters in this subject, but at least in German fighter planes you can adjust the altimeter to the next friendly airfield. I think it's ALT+A.

Edited January 8, 2015 by StG2_Manfred

[-TBC-AeroAce]

Played one mission on campaign with 111 and it seemed like every instrument was reading different to HUD

 

I understand that there is TAS, IAS, Height, altitude (the two are different in aviation terms if u didnt know) ............................

 

 it would be good to get a clear discription of what each one is based on from the DEVS in terms of instruments, bombsite and hud, 

 

for example one thing that was funny about (may be wrong) old il-2 was that the HUD would measure height above ground meaning that you could not fly straight and level using it as the topography would change all the time. I think BOS is more simple they are both pressure based readings i,e they stay at a constant difference. Im think iv got it worked out but would be nice to have a clear explanation of which each instrument and HUD is reading

[Jaguar320]

The altitude indicated in the altimeter on the instrument panel is based on pressure altitude, it can be calibrated to sea level or nearest aerodrome (QNH vs. QFE)

The altitude indicated in the HUD is above ground level (AGL) like a radioaltimeter.

You can check this when flying over the sea it almost the same, then fly over mountainous terrain like Kuban Map and you’ll see.

[Elem]

True altitude: the height above the mean sea level. [Elevation of geographical locations given in maps is actually true altitudes; e.g. the height of the Mount Everest.]

Absolute altitude: absolute altitude is the height from the point on the ground just below the position considered. Or it is the height above the ground level.

Indicated Altitude: altitude from the altimeter, when it is set for the local barometric pressure at the mean sea level. [aircrafts use outside pressure to determine the altitude of the aircraft.]

Pressure Altitude: Pressure altitude is the height above a standard datum air-pressure plane. When the altimeter is set with 1 ATM or 1.0132×10⁵ Pa as the local barometric pressure at the MSL, indicated altitude and the pressure altitude are the same.

Density altitude: Density altitude is defined as pressure altitude corrected for variations from standard temperature. Based on the parameters such as temperature, the pressure at a point can vary from the International Standard Atmosphere. Since all the flight characteristics are in Standard Atmosphere conditions, it is important to know at which altitude in the international standard atmosphere this particular pressure is observed. That altitude is the density altitude.

Also based on physical properties in each region, atmosphere is divided into several altitude regions. They are as follows;

Troposphere : 0 m -8000 m (0-80 km)

Stratosphere : 8000 m -50000 m (8-50km)

Mesosphere : 50000m- 85000 m (50-85 km)

Thermosphere : 85000 m – 675000 m (85-675 km)

Exosphere :67500 m – ~10000000 m (675-10000 km) 

What is the difference between Altitude and Height?

• Height is the distance between two points in the vertical direction.

• Geometric altitude is a height from a datum line to a point above that line.

• In practical applications, in aviation, the height is obtained by comparing the outside atmospheric pressure to the International Standard Atmosphere.

• The main difference between height and a geometric altitude is that altitude has a defined / fixed datum point as a reference.

• Pressure altitude and its derivatives are not comparable to height.

[AEthelraedUnraed]

You guys do realise that this thread is 7 years old?

[Cynic_Al]

1 minute ago, AEthelraedUnraed said:

You guys do realise that this thread is 7 years old?

 

I'm sure it feels very grateful finally to have its question resolved.

[Jade_Monkey]

3 hours ago, AEthelraedUnraed said:

You guys do realise that this thread is 7 years old?

It's good use of the search function instead of creating new threads for the same topic.

[AEthelraedUnraed]

2 hours ago, Jade_Monkey said:

It's good use of the search function instead of creating new threads for the same topic.

...except that it *answers* a question from 7 years ago, rather than expands on it. The sim has changed a lot since then, so the question, which seems to be about a bug (800m is too much difference for the Stalingrad map, no matter how you measure altitude), is likely not even relevant anymore.

Edited August 8, 2022 by AEthelraedUnraed

[6./ZG26_Klaus_Mann]

The Answer is surprisingly simple.

- In Winter the Air is heavier, collects near the Ground more strongly and the Pressure drops much faster in the Climb.

     - It follows that the Altimeter in Winter always reads higher than you are in regards to the Ground, however, to everything regarding Engine   

      Management, the Altimeter is still true. 

- In Summer the Air is lighter and thus spreads upwards more easily and the Pressure drops much slower in the Climb. 

     - As a Consequence your Altimeter in Summer always reads lower than you are. But you still use it for Engine Management as is. 

 

 

Edited August 8, 2022 by 6./ZG26_Klaus_Mann