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View Full Version : Isn't dive acceleration overmodelled in IL FB ?



Hanni8
12-26-2003, 04:01 PM
Was this discussed already ?

I noticed that one can reach astronomical speeds extremely fast even in a shallow 30 degree dive without power in FB. I put a 190 D in a shallow 30 degree dive without power from 5000 m and easily reached 920 km/h. I think even with fullpower this wouldn't be possible in a 30 degree dive.

What do you FB-veterans think about that ?

Hanni8
12-26-2003, 04:01 PM
Was this discussed already ?

I noticed that one can reach astronomical speeds extremely fast even in a shallow 30 degree dive without power in FB. I put a 190 D in a shallow 30 degree dive without power from 5000 m and easily reached 920 km/h. I think even with fullpower this wouldn't be possible in a 30 degree dive.

What do you FB-veterans think about that ?

LeadSpitter_
12-26-2003, 04:49 PM
I totally agree with you, and the 190A/D which had the best high speed elevator response out of any plane in this simulation and reality, which in reality needed trim to pull out of dives 3/4ths of the speed.

Thats one major thing really missing from FB is accurate stick pressure on the elevators in max dives which should occur way before breakup speeds.

Even a really wide spiral descent path in the yaks your speed accellarates so greatly even with the engine off.

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pinche_bolillo
12-26-2003, 04:59 PM
this is certainly an interesting topic for debat, but the problem as I see it is where can one find accurate test data from the real world aircraft?

one thing I have noticed about dive speeds is when you dive from 10,000m even aircraft which had dive limits of mach .7-.75 (about 480-500 mph tas) can reach speeds of 1,100kph tas and nothing bad happens. the aircraft do not start to shake or sufer from compression effect until much lower altitude is reached. I guess it is just a game glich that is hard to model.

an interesting test is the bl-1 rocket plane. at low altitudes (less than 1,000 meters) once you exceed 750 kph tas it shakes badly and tucks under so badly that its uncontrollable. however take it up to 15,000-20,000 meters and dive it. I have reached speeds of 1,500 kph tas at 10,000m and the plane is flying normal.

but hey its a game glitch that I can live with. I have yet to play a game which was perfect

Bull_dog_
12-26-2003, 05:12 PM
I don't believe the dive is right...but I actually think it is undermodelled in all aircraft except the Mig's....Some of my thinking has to do with some things I've read such as P-47's were warned against doing split-S manuevers under 15,000ft lest risking becoming a lawn dart. Escape tactics of heavier aircraft involved diving...there is separation in FB most of the time, but it doesn't seem as profound as what reading pilot acounts makes it out to be. I also don't think that planes broke up like they do in FB...at least at low altitude. They did break up as they approached compressability, but this occurred mainly at high altitudes say above 18,000 ft. In thick air(below 15,000ft.), aircraft would reach a certain dive speed and drag would prevent them from further accelaration...this is not modelled in FB. The heavier/more aerodynamic the plane the higher the speed reached...this is why heavy aircraft like the P-47 and P-38 dove so well and light aircraft like the Spitfire and 109 just didn't do well...at a certain point heavier aircraft just sped away...again I don't believe the separation in aircraft diving is well modelled. Some very aerodynamic aircraft like the mustang could sustain the speed for much longer than others, especially radial fighters and more separation after leveling out. Zoom climbing definitely isn't well modeled...I've seen Jugs with an altitude advantage use this, but rarely have I seen a FB aircraft (given even energy states) like a 190D create much separation from a light aircraft like a Yak-3 after diving and zoom climbing...a little separation, but based on what I've read not the kind of separation I would have imagined.

Not being a pilot, I can only speculate like most of us on these forums...the thing that nags me is how careful you have to fly some planes...like the P-47 or Yak-9's...I don't go into purposefully without a significant energy advantage or I'm dead meat...If it was really that hard I don't think we would be remembering these planes with such affection as it is well known that the 109's service ceiling was much higher than most allied aircraft...the Jugs would have been nothing but flying coffins and it just wasn't so. Energy is the great equalizer but in real combat, it was not so easy to make sure you had altitude and speed on your side....pilot skill counted big time, but I have found that some aircraft in FB that were successful in real combat are only successful when they start with an energy advantage...even escaping in a heavy aircraft is difficult...of course I don't understand the fine points of CEM yet and that may be the reason I haven't seen the differences I've read about. Every WWII pilot know the optimum settings before going into combat; I've been discovering them as I go in multiple aircraft mostly by trial and death http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Having said all of that I still think FB has the most accurate FM's going...especially under 20,000ft...I'm looking forward to BoB to see what the next generation flight modelling has to offer.

Fennec_P
12-26-2003, 05:14 PM
Keep in mind that Vmax speeds are a function of IAS, not TAS.

So if your planes' Vmax is 750km/h IAS, its totally possible to reach 1000+km/h TAS at higher altitudes.

But there seems to be a block preventing you from going supersonic, as you can find with the P-51. As soon as you get near 1200km/h, you explode.

adlabs6
12-26-2003, 06:05 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Bull_dog_:
Some of my thinking has to do with some things I've read such as P-47's were warned against doing split-S manuevers under 15,000ft lest risking becoming a lawn dart. <HR></BLOCKQUOTE>

This always has stuck in my mind. I think I did a split-s in FB with no problems, and I was traveling at 320kmh when I started. I'll have to check again sometime to be sure.

BTW, I once had a P47 installed in my FS2004, and I wondered if that plane would model the stick pressure in a dive. I started at 15,000 feet, and 200 mph if memory serves... Before I had made it into a pure vertical dive, the elevator was useless. I quickly rolled back and wormed out of the dive with a thousand or two feet to spare. Had I reached full vertical dive, I wouldn't have had much of a chance, as by the time I rolled out, I was gaining airspeed like mad.

With dynamics like this, half the manuvers I can pull off in FB at low alts would be doom.

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LEXX_Luthor
12-26-2003, 06:16 PM
Remember in FB 1.0 on the Kuban mountain map you could fly under the map by flying through the grafix cliffs at the south-east map edge you could fly into the cliffs and fly under the map. If you then flew up into the ground from below you popped through zooming to 7000 meters in like 2 seconds, and then your plane would be surrounded by I guess supersonic shock wave water condensation or something. Something weird is in the game.

Mission setup in the thread link below. In latest Patch you can't fly through the grafix cliffs without blowing up (I think).


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PriK
12-26-2003, 10:32 PM
There are definitely inherent limits that Oleg is well aware of including compressibility and perhaps even suitable friction calculations among other things but it's important to be aware that the human factor, the preservation of one's own life, does not apply in the game.

This may sound obvious, but keep in mind that in real life, pilots weren't so casual about approaching the purported limits of their aircraft and most flew them well beneath their operational limits unlike us who can do a little speed test in the game to get a feel for these limitations. What happens in the game is we have the opportunity to attune ourselves to a given aircraft and indeed all of them even, which tends to make us always fly more on "the edge". Structural variances built up after several sorties, such as patched up bullet damage and engine strain, tended to lessen a pilot's potential in a fight especially newer pilots.

These things can account for anecdotal evidence partially I think and are some of the bounderies to realism in the current state of the art. It's a few years off before we get X-Plane flight models but there's certainly a lot of room for improvement, limited only by our processing power, until then.

We may just be groping past the edges of Oleg's simulation universe here at the moment. http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

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pinche_bolillo
12-27-2003, 09:17 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Fennec_P:
Keep in mind that Vmax speeds are a function of IAS, not TAS.

So if your planes' Vmax is 750km/h IAS, its totally possible to reach 1000+km/h TAS at higher altitudes.

But there seems to be a block preventing you from going supersonic, as you can find with the P-51. As soon as you get near 1200km/h, you explode.<HR></BLOCKQUOTE>

fennec, tas is much more critcal than ias. the v mas is always measured as critical mach which is tas not ias.

if the aircraft has a v max of mach .75 then this would about 810 kph tas at 10,000 meters and 912 kph tas at sea level.

a good example of how much ias varied at altitude can be taken from the mustangs placarded speed limitations.

40,000ft 260mph ias which is 495mph tas
30,000ft 290mph ias which is 500mph tas
25,000ft 330mph ias which is 520mph tas
20,000ft 400mph ias which is 530mph tas
15,000ft 440mph ias which is 540mph tas
10,000ft 480mph ias which is 550mph tas
5,000ft 505mph ias which is 560mph tas

so as you can see if a plane has a v max of 505 mph ias at 5,000 ft it cannot do 505 mph ias at 30,000 or 40,000 ft. 505 mph ias at 40,000 ft would put it at or over the speed of sound.

in the case of the bl1 rocket plane I spoke of. at sea level the plane gets uncontrolable at 750 mph tas, the higher you go the lower the safe v max speed gets because the speed of sound lowers the higher you go. at sea level the speed of sound is about 1,200 kph and at 10,000 meters it is about 1070 kph. so if the rocket in this game has a v max speed of 750 kph tas at sea level, then at 10,000 meters it would be lower than 750 kph tas not higher, and my point is that you can reach speeds of 1,500 kph tas at 10,000m in the bl-1, 1,500 kph tas at 10,000 meters is about mach 1.4 yet at sea level the bl 1 can only safely reach speeds of about mach .63

so in the real world if the critical mach was .63 at sea level then at altitudes up to 10,000 meters it would be the same.

[This message was edited by pinche_bolillo on Sat December 27 2003 at 08:38 AM.]