PDA

View Full Version : Oleg, different top speeds for different maps?



robban75
03-01-2004, 01:12 PM
Hi Oleg!

There has been alot of issues concerning topspeeds for certain planes. And most of the time people complain that their fighter of choice is some 10-15km/h too slow according to historical documents.
Now, I mostly conduct my speed tests in the QMB over Crimea. This map allows for historical topspeeds to be met, more or less.
However, doing speed tests on online map Nr:11 gives speeds 10-15km/h slower than on the Crimean map. What is the reason for this? Temperature?
Perhaps getting this out in the open might help avoid future threads about undermodelled airplanes, well at least to some extent!

Cheers!

Robert

http://members.chello.se/unni/D-9.JPG

When it comes to aircombat, I'd rather be lucky than good any day!

robban75
03-01-2004, 01:12 PM
Hi Oleg!

There has been alot of issues concerning topspeeds for certain planes. And most of the time people complain that their fighter of choice is some 10-15km/h too slow according to historical documents.
Now, I mostly conduct my speed tests in the QMB over Crimea. This map allows for historical topspeeds to be met, more or less.
However, doing speed tests on online map Nr:11 gives speeds 10-15km/h slower than on the Crimean map. What is the reason for this? Temperature?
Perhaps getting this out in the open might help avoid future threads about undermodelled airplanes, well at least to some extent!

Cheers!

Robert

http://members.chello.se/unni/D-9.JPG

When it comes to aircombat, I'd rather be lucky than good any day!

Zen--
03-01-2004, 01:27 PM
I second that notion. I saw this phenomenon in the old IL2, in particular on the Kuban mountain maps where all planes seemed as though they were at much greater altitude, even when down on the beach next to the water.

I haven't noticed it as much in FB, but on certain maps planes seem to fly better, or accelerate faster than others.

-Zen-

WWMaxGunz
03-01-2004, 09:41 PM
Temperature and humidity play significant parts in aircraft performance. Not only the engine but the lift and drag, even the mach speed changes which at very high speeds affects drag.


Neal

03-01-2004, 10:27 PM
On the coldest winer maps your IAS reads higher than TAS even at 1000m. Now that's cold!

TgD Thunderbolt56
03-02-2004, 07:50 AM
Good point. I know and understand the factors that affect potential airspeed, but is this actually modeled? Or is it just a quirk?

Either way, no biggie but I am curious.



http://home.earthlink.net/~aclzkim1/sitebuildercontent/sitebuilderpictures/il2sig2.jpg

Oleg_Maddox
03-02-2004, 08:23 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by robban75:
Hi Oleg!

There has been alot of issues concerning topspeeds for certain planes. And most of the time people complain that their fighter of choice is some 10-15km/h too slow according to historical documents.
Now, I mostly conduct my speed tests in the QMB over Crimea. This map allows for historical topspeeds to be met, more or less.
However, doing speed tests on online map Nr:11 gives speeds 10-15km/h slower than on the Crimean map. What is the reason for this? Temperature?
Perhaps getting this out in the open might help avoid future threads about undermodelled airplanes, well at least to some extent!

Cheers!

Robert

http://members.chello.se/unni/D-9.JPG

When it comes to aircombat, I'd rather be lucky than good any day!<HR></BLOCKQUOTE>

Yes, you right. Becasue we have differennt physical conditions in different regions.

In measurements of real aircraft performance ussuall used realtive formulas that to get true things.
The map of crimea met these standards that are exactly to the things that do not use these formulas of recalculations.

This just show how deeep we try to model all things http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

SeaFireLIV
03-02-2004, 08:37 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Oleg_Maddox:


Yes, you right. Becasue we have differennt physical conditions in different regions.

In measurements of real aircraft performance ussuall used realtive formulas that to get true things.
The map of crimea met these standards that are exactly to the things that do not use these formulas of recalculations.

This just show how deeep we try to model all things http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif<HR></BLOCKQUOTE>

Very interesting. So now, our most ardent testers need to specify WHERE they test their planes!

SeaFireLIV...

http://img12.photobucket.com/albums/v31/SeaFireLIV/P47duck.jpg

Oleg_Maddox
03-02-2004, 08:51 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SeaFireLIV:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Oleg_Maddox:


Yes, you right. Becasue we have differennt physical conditions in different regions.

In measurements of real aircraft performance ussuall used realtive formulas that to get true things.
The map of crimea met these standards that are exactly to the things that do not use these formulas of recalculations.

This just show how deeep we try to model all things http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif<HR></BLOCKQUOTE>

Very interesting. So now, our most ardent testers need to specify WHERE they test their planes!

SeaFireLIV...

http://img12.photobucket.com/albums/v31/SeaFireLIV/P47duck.jpg

<HR></BLOCKQUOTE>

Really we alredy told it - test on Crimea map. Especially Sea Level speeds

Oleg_Maddox
03-02-2004, 08:52 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
Temperature and humidity play significant parts in aircraft performance. Not only the engine but the lift and drag, even the mach speed changes which at very high speeds affects drag.


Neal<HR></BLOCKQUOTE>

Correct. This is also true for different Regions and different time of the year.
And we also model it as well.

Gunner_361st
03-02-2004, 09:05 AM
Wow, you gentlemen even model temperature and humidity effects? Good show! Wow, learn something new and cool every day about FB every day. http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Captain Gunner of the 361st vFG

http://home.comcast.net/~smconlon/wsb/media/245357/site1039.jpg

BfHeFwMe
03-02-2004, 09:25 AM
I think what he just said is the Crimea map is modeled to a perfect standard day equivalence. That's the benchmark condition all flight performance charts are based off. As I recall it's something like 15 degrees C temp at sea level, not sure exactly what the pressure altitude was, but that's a preset value also.

robban75
03-02-2004, 09:32 AM
Thanks for the reply Oleg! I'll be sure to spread the word! http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

http://members.chello.se/unni/D-9.JPG

When it comes to aircombat, I'd rather be lucky than good any day!

Maple_Tiger
03-02-2004, 09:35 AM
I did not know this.

Thanks all for bringing this up and thank you Oleg for taking the time to answer are questions.

Ill try the Crimea map from now on.

Capt. 361stMapleTiger.

http://www.imagestation.com/picture/sraid78/pd6c878f0006c224805da6c9645408b41/fb291d3e.jpg

Proud member of the FBAA and Nutty Philosohpy Club.

WWMaxGunz
03-02-2004, 08:58 PM
Originally posted by BfHeFwMe:
I think what he just said is the Crimea map is modeled to a perfect standard day equivalence. That's the benchmark condition all flight performance charts are based off. As I recall it's something like 15 degrees C temp at sea level, not sure exactly what the pressure altitude was, but that's a preset value also.

Don't forget humidity. Humid air is heavier, better lift, and it helps the engine run just a bit cooler from more latent heat absorbtion capability. Cars get better mileage in the rain, or at least my old volks' type 3's all did like 5%. There was even a water injection kit for those and may be for others.


Neal

BfHeFwMe
03-02-2004, 09:16 PM
I've yet to see a SMOE based performance chart take humidity into account for performance, exception for water depth on a runway affecting braking distance. ATIS may give you the dewpoint, but where in the charts do you ever use it?? Besides figuring for icing conditions.;)

WWMaxGunz
03-03-2004, 12:09 AM
Well if it's not on your chart, it must not be real.

Forget what the meteorologists, physicists and engine people say because it's not on those charts.


Neal

LuftKuhMist
03-03-2004, 12:21 AM
Is it me or during winter we get better performance?

http://www.ifrance.com/boussourir/MOMS.gif
http://www.ifrance.com/boussourir/grab0004.jpg

WWMaxGunz
03-03-2004, 01:00 AM
Colder air is denser. Denser air is more lift. Colder air is more oxygen per liter going through the engine intake. Engine cools off better in colder, denser airflow. Radiator works better. Even at night if the air is cooler, planes fly better and it is easier to take off and climb. Ask experienced pilots.


Neal

rbstr44
03-03-2004, 07:51 PM
Originally posted by Oleg_Maddox:
[ellided previous quotes]
Yes, you right. Becasue we have differennt physical conditions in different regions.

In measurements of real aircraft performance ussuall used realtive formulas that to get true things.
The map of crimea met these standards that are exactly to the things that do not use these formulas of recalculations.

This just show how deeep we try to model all things :)

Thanks, Oleg, for helping us understand the modeling of atmospheric conditions!

Questions:
1) Does that mean that aircraft altimeters (both virtual cockpit guage and speedbar) display Indicated Altitude, and are not corrected for Density Altitude on most maps?

2) Given what was said about Crimea being the best map for testing, does the atmospheric altitude modeling use standard pressure, temperature, and density for any given altitude on the Crimean map only (i.e., Indicated Altitude == Density Altitude in Crimea)?

rbstr44
03-04-2004, 03:04 AM
*bump*

Ivank
03-04-2004, 04:33 AM
As a tester I offer the following.

In those FM tests I have performed Crimea is the datum. Crimea represents FB's version of a Standard ISA atmosphere. If you take the time you can actually derive FB's atmosphere. Temperature lapse rates etc. Crimea is Very close to ISA up to 10,000m.

Winter maps will naturally result in different performance (generally better). Out of intest this has been there since IL2 :)

There are few Sims that model different atmospheres !

rbstr44
03-04-2004, 06:44 PM
Ivank, thank you for answering my question. It is fascinating to me that one can derive the atmosphere with empirical testing in FB (now AEP, too http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif ). I might want to try that out on one of the other maps. And by implication, the Density Altitude and the Indicated Altitude are very close to the same value in Crimea since that map's atmosphere resembles the ISA (International Standard Atmosphere) model. What a detailed sim!! http://ubbxforums.ubi.com/images/smiley/11.gif