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View Full Version : Altimeter Settings in the P39 and Spit



MA_Moby
11-02-2004, 07:04 AM
I'm not the first to say that the accuracy of the cockpit deatil in the IL2 series is just fantastic. http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

However I've noticed a curious highly amusing thing (if you're me http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif) that I wanted to share.

I was trying ou the P39D1 last night, when I had a close look at the altimeter. Altimeters are basic barometers that measure air pressure. However as the ambient air pressure at sea level changes all the time as the result of weather systems, the pilot has to manually adjust the altimeter to the correct setting. I was having a look to see what this was set at. It read 0000mb! Now a more usual setting would be something like 0996mb in low pressure conditions, or 1021mb in high pressure. But 0000mb! That's a vacuum.

http://premium.uploadit.org/MAMoby/altP40D1.jpg

So I decided to take a look at another aeroplane. The spitfire MKiX. On this altimeter there wasn't even a setting window.

http://premium.uploadit.org/MAMoby/altspitIX.jpg

Which I know to be incorrect because I'd snapped the cockpit of a MK IX recently -

http://premium.uploadit.org/MAMoby/spitalt.jpg

Note the settings on the right hand side of the dial.

Obviously even a pedant like myself couldn't be arsed to go and check all the altimeters on the aircraft.

But it got me wondering.

If the planes are flying in air with zero pressure, do they, should they, still fly? The Bernoulli and Newtonian models of flight would say no, but the IL2 principles say yes! http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

NegativeGee
11-02-2004, 09:15 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by MA_Moby:
If the planes are flying in air with zero pressure, do they, should they, still fly? The Bernoulli and Newtonian models of flight would say no, but the IL2 principles say yes! http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif <HR></BLOCKQUOTE>

Its a bit moot really as if 0000Mb was the case the pilot would have boiled to death.

MA_Moby
11-02-2004, 09:24 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by NegativeGee:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by MA_Moby:
If the planes are flying in air with zero pressure, do they, should they, still fly? The Bernoulli and Newtonian models of flight would say no, but the IL2 principles say yes! http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif <HR></BLOCKQUOTE>

Its a bit moot really as if 0000Mb was the case the pilot would have boiled to death. <HR></BLOCKQUOTE>

http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

oh well - time for someone to model a pilot in a spacesuit

darkhorizon11
11-02-2004, 09:39 AM
I can't explain the 0000mb, just a bug, but you can't adjust pressure and temperature in this game. The game engine just assumes standard temperature and pressure anyway.

As for the Spit, it could just be a mistake in the game. Remember, most planes today have Sensitive Altimeters which means they can be adjusted to standard pressure. But this is not a requirement, some older aircraft have more basically altimeters that need to be dis-assembled by a technician to be adjusted. Generally you don't take off in a Sensitive alt. unless you have the correct alt. setting and it reads +-75 feet of field elevation when your on the ground. In the good ol' USA Sensitive Altimeters are required for IFR, but any regular approved alt. will due for VFR.

Getting back to your picture, perhaps this Spit got an upgrade and got a better altimeter. Is that aircraft still flown on a regular basis? Maybe it got an overhaul sometime after the war?

Or maybe the modeler was just a weee bit lazy. http://forums.ubi.com/images/smilies/88.gif

MA_Moby
11-02-2004, 10:13 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by darkhorizon11:
I can't explain the 0000mb, just a bug, but you can't adjust pressure and temperature in this game. The game engine just assumes standard temperature and pressure anyway.

As for the Spit, it could just be a mistake in the game. Remember, most planes today have Sensitive Altimeters which means they can be adjusted to standard pressure. But this is not a requirement, some older aircraft have more basically altimeters that need to be dis-assembled by a technician to be adjusted. Generally you don't take off in a Sensitive alt. unless you have the correct alt. setting and it reads +-75 feet of field elevation when your on the ground. In the good ol' USA Sensitive Altimeters are required for IFR, but any regular approved alt. will due for VFR.

Getting back to your picture, perhaps this Spit got an upgrade and got a better altimeter. Is that aircraft still flown on a regular basis? Maybe it got an overhaul sometime after the war?

Or maybe the modeler was just a weee bit lazy. http://forums.ubi.com/images/smilies/88.gif <HR></BLOCKQUOTE>

Yes the Spit is still flown in the UK. It was converted to a T. IX after the war, so it's possible an instrument upgrade took place then, though as far as I know Spits were equipped with adjustable altimeters. Other spit cockpit photos I've seen would seem to indicate this to be the case, with the settings shown either on the right or in a botton central position.

Here in the UK there are a plethora of different altimeter setting. QFE for airfield elevation, QNH for sea level (which could be airfield QNH or regional QNH), then various setting regions. It's drummed in the flying with the wrong setting could be very dangerous. After all 1mb of error = 35 feet or so! But I hear things are more relaxed under FAA regulations.

Anyway, I pointed this out for more tongue in cheek reasons than anything else (after all the other strange things I've seen people pick up on and moan about http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif), as it does not effect the enjoyability of the game in any way. If I seriously wanted to adjust pressure settings I'd fly MS Flight! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

ucanfly
11-02-2004, 10:27 AM
What I think is a worse omission is lack of 10,000 ft marker on most planes that use English units, especially with those of us that have ADD or short term memory loss.

ucanfly
11-02-2004, 10:28 AM
What I think is worse is the lack of the 10,000 ft marker on most planes that use English units.

TX-EcoDragon
11-02-2004, 12:58 PM
Before IFR flight was common practice not all altimeters were "sensitive altimeters" ie, they may not have a Kollsman window for adjustment to a local altimeter settin. As far as the P-39, I'd just say that it probably goes in the category with the non-op instruments, the mags in the off position at all times (in many aircraft), the off the peg suction indication in the 39. . . etc etc. I know that BBB_Hyperion has been interested in the ways in which the sim handles atmospheric pressure and temperature changes, lapse rate, etc. Maybe he will chime in if he has found anything regarding what is implemented. . . though I have confidence that it isn't 0000mb ;-)


Edit, I guess I should read all the replies before making my own eh??

Lol

WTE_Galway
11-02-2004, 07:32 PM
so why does that restored Mk IX have a max altitude of 10,000 feet ?

J_Weaver
11-02-2004, 08:09 PM
It possibly doesn't have a working oxygen system and unless i'm mistaken above 10,000ft a pilot should be on oxygen.

MA-Moby
11-03-2004, 03:41 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by J_Weaver:
It possibly doesn't have a working oxygen system and unless i'm mistaken above 10,000ft a pilot should be on oxygen. <HR></BLOCKQUOTE>

That would seem likely. It's a modern sign. And above 10,000ft you'll get hypoxia sooner or later.

hop2002
11-03-2004, 10:15 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Yes the Spit is still flown in the UK. It was converted to a T. IX after the war, so it's possible an instrument upgrade took place then, though as far as I know Spits were equipped with adjustable altimeters. <HR></BLOCKQUOTE>

I've got a copy of the Spit IX manual, reissued 1946, and it shows an altimeter with the adjustment window (although it's at the 6 o'clock position)

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>so why does that restored Mk IX have a max altitude of 10,000 feet ? <HR></BLOCKQUOTE>

It looks to me like there's a short hand behind the long hand, which would presumably read 10,000ft increments.

MA_Moby
11-03-2004, 11:41 AM
Here are the full piccies for anyone intersted:

Front seat:

http://premium.uploadit.org/MAMoby/spitcockpitfront.jpg

Rear Seat:

http://premium.uploadit.org/MAMoby/spitcockpitrear.jpg

Ain't she lovely?

http://premium.uploadit.org/MAMoby/spit2seat.jpg

It was originally a LF.IX of the Canadian air force and took part in Normandy, where it (and it's pilot) were credited with a kill. It was then sold to the Irish air force and converted to a Tr.IX. Restored in 1993.

TX-EcoDragon
11-03-2004, 01:22 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by MA-Moby:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by J_Weaver:
It possibly doesn't have a working oxygen system and unless i'm mistaken above 10,000ft a pilot should be on oxygen. <HR></BLOCKQUOTE>

That would seem likely. It's a modern sign. And above 10,000ft you'll get hypoxia sooner or later. <HR></BLOCKQUOTE>

From a US regulatory standpoint a pilot does not need supplemental oxygen for 30 minutes when between 12,500 and 14,000 feet. . . beyond that, or above 14,000 oxygen must be used, though there are plenty of portable units that could be used, so it's not this issue that is the factor. Instead it would be my guess that there is no transponder on-board the aircraft which is used to augment the primary radar target ATC receives with a secondary target that is capable of conveying an identifying 4 number code and in the case of Mode S or C transponders it will aslo report altitude information to ATC without the pilot needing to tell them.

voyager_663rd
11-03-2004, 02:02 PM
http://img.photobucket.com/albums/v37/voyager_663rd/detail_spitfire_ix_33.jpg

Original guage on a MKIX. At 6 o'clock position.

LStarosta
11-03-2004, 03:26 PM
Remember kids, just because the plane is the same doesn't mean the avionics are http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif.

EcoDragon is correct. Depends, too on what FAR's you're under. Part 135 is stricter than Part 91. I can tell you that I took my Cessna 150 up to around 10,000 for a while, and you don't notice it at first, but after a while you find yourself giggling at the most mundane of things such as the "Pull For Quick Erect" knob under the Art. Horizon! http://forums.ubi.com/images/smilies/35.gif