American Altimeter landing problem
#1

I've searched but can't seem to find a fix for this, please can anyone tell me if there is a workaround for the zero feet problem I'm getting when landing some American aircraft? I've only just noticed this because I don't often land non-Japanese aircraft. :wink:

P38's, 39's and Corsair's all read 60-70m when the wheels are on the runway, yet Japanese planes like the Ki-84 read zero feet correctly...

[Image: altimeterzp2.jpg]

Thanks Smile
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#2

Dont know if this is modeled in IL2 but typically altimeter should read field elevation and not zero unless you are flying from an airfield at sea level. The altimeter has an adjustment knob for setting this in RL.
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#3

Am a little puzzled by your screenshots.

The P-38's altimeter is showing approximately 225 ft and speedbar is showing 70 meters field elevation.

I'm not sharp on converting meters to feet; can someone else do the math ?

But your speedbar is showing 70km/h. Are you flying ? That's a heck of a taxi speed.

In the KI-84 you're doing 100km/h at 0 meters. You'd really get a speeding ticket for that one.

Sounds like a speedbar problem. Trust your gauges in the meantime.

Here is a shot taken at Caen in a P-38 on the tarmac.

All is good here.

[Image: p38altimeterex1.jpg]

Here's the Ki-84 at Caen. I'm not sure what the altimeter gauge is.

[Image: ki84altimeterlo6.jpg]
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#4

Gauge and speedbar values are correct 1 ft = 30,48 cm
so that 70m = 7000cm , 7000cm / 30,48cm ~ 229ft
and yes altitude depends on sealevel
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#5

You're right! It's altitude above sea level - Doh!

I have noticed this before but never as much as 70m difference and I thought whatever was happening was getting worse in some way...

Sorry for being such a nube but since upgrading my graphics card (GeForce 6200 to GeForce 9600GT) I've started noticing so much more lol. Big Grin

This is a P38 landing on the same AB as the Ki-84 (QMB Pacific Islands)

[Image: grabaltfu5.jpg]


@KC Jones

The Ki-84 and this grab are both AI landings (I think in one of the training NTRACKS it says no more than 100km/h when you pass over the start of the runway - notice the AI's 130km/h in the latest screen capture!).
The P38 screenshot in my first post was my landing and my wheels had just touched the runway - I could've chopped the throttle a bit more but bear in mind from what I was seeing there was a possibility that I still had over two hundred feet below me! Big Grin
Yes that is the altimeter in a Ki-84

Thanks everyone Smile
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#6

Rookie67 Wrote:Gauge and speedbar values are correct 1 ft = 30,48 cm
so that 70m = 7000cm , 7000cm / 30,48cm ~ 229ft

Whew ! Do you have any type of "nursery rhyme" type calculation that's easier to use ? Something like "multiply this by that" to get "whatever" ?

I'd go nuts trying to work that out in me head Confusedhock:

PDelaney, not to worry as long as its all sorted out.

You just have me puzzled by your "tarmac" speed :mrgreen:

Next time just post a picture of an engine-off bird.

Take care
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#7

1 meter is about a yard, so just multiply or divide by 3. So, 100 meters=300 feet.
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#8

Altitude: The distance from the aircraft's reference point (static intake) to a given pressure surface (eg. 1013 hPa or 29.92mm/HG) measured in a given unit of measurement (meters, feet)
This is the one you use in real life for reference, and the pressure surface is set by reducing the pressure at given points to MSL (mean sea level) using ICAO Standard athmosphere conditions.

Height: The distance from the surface of the ground/lake to the reference point on the relevant aircraft.

So unless I'm too sleepy to formulate it correctly(just woke up) this is how it is in the game as well.

Try opening your cockpit (wonderwoman) and fly over some mountains, the speedbar shows altitude above MSL, and the dial in the WW view shows true altitude or height above the terrain.
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#9

KC Jones Wrote:
Rookie67 Wrote:Gauge and speedbar values are correct 1 ft = 30,48 cm
so that 70m = 7000cm , 7000cm / 30,48cm ~ 229ft

Whew ! Do you have any type of "nursery rhyme" type calculation that's easier to use ? Something like "multiply this by that" to get "whatever" ?

I'd go nuts trying to work that out in me head Confusedhock:

OK here it comes:
In the first picture the altitude indicated in the speedbar was 70 meters and the altitude on the gauge was 229 feet and the question was if this is right.
Now 1 feet are 30,48 centimeters.
If you want to know how many feet are 70 meters, you have to transform the meters in cm by multiplying them by 100. (because 1 meter are 100 cm)
This means 70 meters = 7000 centimeters
if you divide this 7000 cm by 30,48 cm the result is nearly 299,65 and this is the number of feet that match into 70 meters, so 70 meters = 229 feet

so gauges and speedbar show the correct value, but in different measurement units

Ok ?
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#10

Rookie67 Wrote:
KC Jones Wrote:
Rookie67 Wrote:Gauge and speedbar values are correct 1 ft = 30,48 cm
so that 70m = 7000cm , 7000cm / 30,48cm ~ 229ft

Whew ! Do you have any type of "nursery rhyme" type calculation that's easier to use ? Something like "multiply this by that" to get "whatever" ?

I'd go nuts trying to work that out in me head Confusedhock:

OK here it comes:
In the first picture the altitude indicated in the speedbar was 70 meters and the altitude on the gauge was 229 feet and the question was if this is right.
Now 1 feet are 30,48 centimeters.
If you want to know how many feet are 70 meters, you have to transform the meters in cm by multiplying them by 100. (because 1 meter are 100 cm)
This means 70 meters = 7000 centimeters
if you divide this 7000 cm by 30,48 cm the result is nearly 299,65 and this is the number of feet that match into 70 meters, so 70 meters = 229 feet

so gauges and speedbar show the correct value, but in different measurement units

Ok ?
and thank you for the algebra math lesson guys.
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#11

Guys,

Tell you what. The speedbar altitude was not a real problem; it was the speedbar "speed" that threw me off. Since I assumed a "standing still" airplane that's why I questioned if the speedbar was faulty. The question had to do with differences in airport readings for American aircraft. He was talking metric while describing an American airplane. I should've stayed out of it as I don't speak "metric".

From now on I'm just going to keep my eyes on "my" gauges (mph/ft), and shoot when I think a bandit is within range.

If someone talks kilometers or meters to me I'll ask for a translation as he rolls into a death spiral Big Grin

I don't want to think about and calculate bullet drop at co-alt via temperature decrease of 2 degrees C per 1000ft alt gain nor a 1 inch Hg loss of pressure per 10000 alt gain. Confusedhock:

You say "tomato" and I'll say "potatoe" :lol: "Let's call the whole thing off" [old '40s song]

But seriously guys, it makes me wonder about WWII "immersion" when I hear folks/squadrons talking metric when flying American-made aircraft. Turn the speedbar off and learn the instruments. *hint* *hint*

And yes I do cite Celsius temperature for flight planning using the E6-B Flight Computer as that is the norm....in the civilian world.

And PDelaney, you mentioned you were'nt sure of your distance to the ground (AGL) when landing and when to chop the throttle. Learn to just watch the runway/airstrip coming up visually with your peripheral vision. You'll know when to chop the throttle which should be now being reduced slowly to stall speed. It will take practice and I suggest you build a single mission just for the purpose of takeoff and landing, so you can save the track and re-view it for what went wrong and what went right.

May I suggest Zeus-Cats "Straight from the Farm" training missions/practices available at M4T.

In other words don't rely on your alitmeter to decide when to touch down - use your "visual" Luke ! :mrgreen: You don't need to know the field's elevation.

Whew ! Now for a second cup o' joe.

Just a helpful illustration on some terms:

[Image: mslaslaglru9.jpg]

[Image: tastn6.jpg]
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#12

Good stuff, but misses airspeed. True airspeed = altitude adjusted speed +- wind velocity which either makes you faster or slower relative to ground speed. Since you are trying to go somewhere, ground speed is what you want to know to see how "fast" you are going!

BTW, the internet is your friend.. there are a zillon different ways to answer most questions with a simple google search, and there are tons of math/unit converters...
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#13

Spinnetti Wrote:Good stuff, but misses airspeed. True airspeed = altitude adjusted speed +- wind velocity which either makes you faster or slower relative to ground speed. Since you are trying to go somewhere, ground speed is what you want to know to see how "fast" you are going!

BTW, the internet is your friend.. there are a zillon different ways to answer most questions with a simple google search, and there are tons of math/unit converters...

True Airspeed is not calculated using wind velocity only ground speed is affected by wind velocity.

Let me try to explain so you can understand. The aircraft once it becomes airborne is now operating in a large fluid namely air. Fluid speed ( windspeed )is a value we assign when this fluid is moving relative to a fixed point ( Me standing at a weather station). A good example is the fishbowl analogy. a fish is swimming around in his bowl of water ( substitute air for water ) at 2 knots through the water in a circle so his ground speed is almost nil. You pick up the fishbowl and start running at 15 knots for an hour( This is the windspeed). The fish is still swimming through his fluid at 2 knots no matter what direction he goes but his ground speed is 15 knots. Substitute an aircraft for the fish. Do you see yet. Yes the modern pitot static system works on ram air or dynamic pressure of the fluid into the forward facing opening but as far as the aircraft and its fluid that it is operating in it is always facing forward.

True airspeed is the actual speed of the aircraft plus or minus any errors in the airspeed indicator or the pitot/static system and allowances for altitude. Indicated airspeed is what your airspeed indicator is reading. The only thing that is affected by the velocity of the wind is your groundspeed. It does not affect your true airspeed. What affects your true airspeed is changing the AOA.

http://www.airliners.net/aviation-forum ... ain/75475/
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#14

Congompasse Wrote:
Spinnetti Wrote:Good stuff, but misses airspeed. True airspeed = altitude adjusted speed +- wind velocity which either makes you faster or slower relative to ground speed. Since you are trying to go somewhere, ground speed is what you want to know to see how "fast" you are going!

BTW, the internet is your friend.. there are a zillon different ways to answer most questions with a simple google search, and there are tons of math/unit converters...

Airspeed is not calculated using wind velocity only ground speed is affected by wind velocity.

Let me try to explain so you can understand. The aircraft once it becomes airborne is now operating in a large fluid namely air. Fluid speed ( windspeed )is a value we assign when this fluid is moving relative to a fixed point ( Me standing at a weather station). A good example is the fishbowl analogy. a fish is swimming around in his bowl of water ( substitute air for water ) at 2 knots through the water in a circle so his ground speed is almost nil. You pick up the fishbowl and start running at 15 knots for an hour( This is the windspeed). The fish is still swimming through his fluid at 2 knots no matter what direction he goes but his ground speed is 15 knots. Substitute an aircraft for the fish. Do you see yet. Yes the modern pitot static system works on ram air or dynamic pressure of the fluid into the forward facing opening but as far as the aircraft and its fluid that it is operating in it is always facing forward.

Egards ! See what you started PDelaney ! :roll:

I knew it was going to come down to this.

First Spinnetti, ..my last inserted picture is how you compute true airspeed (TAS). I should have so stated. Wind is not involved in computing it.

Your observation was about groundspeed. That is where wind (if any) is taken into account.

Congompasse, your explanation is "fishy" but good. :mrgreen:

I always believe a picture is worth a thousand mile journey.

Here's a couple of pictures about groundspeed and wind.

They may be over 20+ years old but are still valid. Here's a downloadable sample at http://www.rodmachado.com/Images/Privat ... 20Here.pdf


[Image: rodmachadoe6b1yn2.jpg]

[Image: groundspeedpx5.jpg]

Computing true airspeed (TAS)

[Image: tastn6.jpg]

Download more samples from Rod's Private Pilot Handbook at

http://www.rodmachado.com/Product/Books ... cerpts.htm
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#15

Congompasse, your explanation is "fishy" but good.

I like people with a sense of humor though it does get frustrating trying to explain that headwinds or tailwinds have nothing to do with airspeed. KC where are you in Virginia.
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