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View Full Version : why can't I get over 250mph at altitude?...



hi_stik
04-21-2006, 10:58 AM
I am flying a P-51D at 23,000ft. I am at full power, fully trimmed, radiator closed, and between 70%-100% prop pitch (experimenting back and forth), and yet my plane will not exceed 250mph? Is this a problem w/ the flight model, or am I just not doing something right? I have tried to change mixtures (it must be automatic, because nothing happens; same thing w/ supercharger speeds), and nothing. Can someone explain this to me?

JG53Frankyboy
04-21-2006, 11:32 AM
what is this in TAS ?
unfortunatly the TAS gauge (the "comic"gauge when using nocockpit view) is only showing km/h

MrMoonlight
04-21-2006, 11:33 AM
This question pops up every now and then...

Most "Maximum Speeds" are quoted in True Airspeed. The speed you read from your airspeed indicator is given in (logically) Indicated Airspeed.

Without going into all of the scientific details, suffice it to say that at high altitude the air is much thinner, so the pressure of the air being forced into the pitot tube is considerably less than it would be at sea level. Thus the speed indicated is actually less than the speed you are traveling relative to your environment. In a "no wind" situation, your TAS would also be your groundspeed, i.e., your speed relative to the earth's surface (a headwind or tailwind will also influence your groundspeed).

The general rule of thumb is to add 2% of your IAS for every thousand feet of altitude, and that will roughly give you your TAS.

In your case 2% of 250 mph would be 5 mph. Multiply that by 23 (for the thousands of feet) and that gives you 115 mph. So you're flying roughly 365 mph TAS.

Hope this shed some light.

HotelBushranger
04-21-2006, 11:40 AM
That helps a lot http://forums.ubi.com/images/smilies/25.gif

knightflyte
04-21-2006, 11:54 AM
Okay, I understand that now.......very interesting.

But why do other planes pass me like I'm standing still? Regain altitude much quicker than me? Don't seem to stall or feel like I'm on the knife's edge of manueverability?

I know the air is thinner.......but. Well is that ME or is it the game?

I rarely fly over 3 - 5000 meters because it seems so fruitless to keep up with AI planes.

If I'm doing something wrong are there any tips to make it 'enjoyable' to fly high?

hi_stik
04-21-2006, 12:01 PM
I am aware of the discrepancy in airspeed readings because of atmospheric anomalies, but I thought the speed bar was a "true" gauge. Still, even at 365mph TAS, that's still well below the max. airspeed of the P-51. right?...

vonStahlhelm
04-21-2006, 01:05 PM
ok, the air is thinner in high altitudes, so that the airspeed tube is not accurate.
but whats up wit flight behaviour of the plane itself? it seems to me that the planes in high altitudes react like fliying very slow and the nose will drop downwards like in etxrem slow flight in low altitudes.

NonWonderDog
04-21-2006, 01:36 PM
That's because the handling of the plane is roughly dependent on IAS, not TAS. If the indicator says 250 mph, the plane will fly roughly as if the indicator showed 250 mph at any other altitude.

If you want to get picky, the handling of the plane is actually a function of both density and Mach number. For this reason, a plane at 30,000 feet and 250 indicated will fly differently than a plane at sea level and 250 indicated, due to the change in temperature and, by extension, the speed of sound.


To the orignal poster:
Some planes require manual adjustment of fuel mixture and supercharger stage as you gain altitude. On these planes you have to lean the fuel and switch to a higher supercharger gear, or the plane will lose a great deal of performance. The P-51 shouldn't be one of those, however...

VW-IceFire
04-21-2006, 04:39 PM
Originally posted by hi_stik:
I am aware of the discrepancy in airspeed readings because of atmospheric anomalies, but I thought the speed bar was a "true" gauge. Still, even at 365mph TAS, that's still well below the max. airspeed of the P-51. right?...
Nope...ok...the TAS guage is in the virtual or "wonderwoman" cockpit view. I forget the key control but its in there...its a virtual cockpit only. It shows the true air speed in relation to the ground in KPH.

The Mustang roughly comforms to the speed charts that have been released for the versions we have. They may be off give or take 10 kph but thats not a huge discrepancy. Usually this is because the speed over all altitudes is not completely accurate to real world data...but its very close and you shouldn't expect it to be fully accurate on a $1000 home PC.

As for other planes making you feel like your standing still...probably has alot to do with how you fly it. Thats huge in everything in this game.

Cobra427so
04-21-2006, 05:11 PM
And someone will correct me if I'm off here, but the reason AI can pull away is that they can use 100% (+) power settings with no ill effects in the game - as the player, you can't. Many times I've seen AI use full flaps in the game to maintain formation (at speed), if you try to do that your flaps will jam.

Niggling little things like that we have to live with.

Cobra427so.

mortoma
04-21-2006, 07:30 PM
Originally posted by knightflyte:
Okay, I understand that now.......very interesting.

But why do other planes pass me like I'm standing still? Regain altitude much quicker than me? Don't seem to stall or feel like I'm on the knife's edge of manueverability?

I know the air is thinner.......but. Well is that ME or is it the game?

I rarely fly over 3 - 5000 meters because it seems so fruitless to keep up with AI planes.

If I'm doing something wrong are there any tips to make it 'enjoyable' to fly high? What are you considering to be a "high" altitude?? And are you flying with AI aircraft of the same type you are flying?? Is this in a Dgen ( dynamic ) campaign? Or maybe missions you are building yourself in Full mission builder or possibly just the Quick mission builder?? I'd think it's not Dgen campaign missions you're flying because you rarely have to fly over 15,000 ft. in those.

In any case, it's almost always possible to keep up with AI in your flight flying in the same aircraft, with few exceptions. There are a few planes that Dgen assigns a very high cruise speed to, which is almost top speed. Since the AI don't have to slow down for overheating, in those planes it's very hard to keep up. One plane I had this difficulty with was the FM-2, in a Pacific Dgen campaign I was flying. I remedied that easily though by going into the Dgen folder under tha main game folders and editing a file called "Pacificplanes.dat". I edited the value for the cruise speed. Then my AI flight buddies slowed down to that new speed from then on so I could keep up.

But this is only a few planes that have this problem. In the other planes I have no trouble keeping up and edited nothing. You just have to keep up in the intial climb right after takeoff.
Many newcomers to the game make the mistake of trying to climb after the AI way too aggressively, thereby getting their nose too high and slowing to a climb speed that is too slow. In this case the AI will run away from you. Keep your nose under control and climb at a faster climb speed if this is that case. Don't point your nose or gunsight at the AI planes you are trying to keep up with, this is usually too nose high. Keep them high in your windscreen instead and in some planes, you almost have to keep them up high out of view or nearly so.
This best speed to keep up with them might be higher than the optimum climb speed, which is called "Vy" or "best rate of climb". A plane may have the best climb rate at 270 KPH but you may get better results keeping up with AI climbing at 350 Kph, for example. If you continue to have trouble still, repost in here and I can help you out.

Truth is you can keep up with the AI in any plane in the game if their cruise speed is not too high and as I explained, this can be fixed anyway. I keep up with AI all the time and have done it in every flyable plane we have.

VW-IceFire
04-21-2006, 07:57 PM
Originally posted by Cobra427so:
And someone will correct me if I'm off here, but the reason AI can pull away is that they can use 100% (+) power settings with no ill effects in the game - as the player, you can't. Many times I've seen AI use full flaps in the game to maintain formation (at speed), if you try to do that your flaps will jam.

Niggling little things like that we have to live with.

Cobra427so.
Even if you turn off engine CEM, overheats, and the whole nine yards...the AI is still faster. They don't loose energy...

NonWonderDog
04-21-2006, 09:47 PM
Another problem is that the AI tries to maintain their set cruise speed during climb. They often need to go to WEP to do this, since a lot of the cruise speeds are set kind of high.

We, of course, can't climb at WEP indefinitely. Even if we change the realism settings to do so, the best we can do is maintain position however far behind, unable to catch up until the AI gets to altitude. It's really damn annoying.

joeap
04-22-2006, 02:44 AM
Originally posted by VW-IceFire:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Cobra427so:
And someone will correct me if I'm off here, but the reason AI can pull away is that they can use 100% (+) power settings with no ill effects in the game - as the player, you can't. Many times I've seen AI use full flaps in the game to maintain formation (at speed), if you try to do that your flaps will jam.

Niggling little things like that we have to live with.

Cobra427so.
Even if you turn off engine CEM, overheats, and the whole nine yards...the AI is still faster. They don't loose energy... </div></BLOCKQUOTE>

But they use the same FM right. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif http://forums.ubi.com/images/smilies/shady.gif

mortoma
04-22-2006, 06:12 AM
Originally posted by NonWonderDog:
Another problem is that the AI tries to maintain their set cruise speed during climb. They often need to go to WEP to do this, since a lot of the cruise speeds are set kind of high.

We, of course, can't climb at WEP indefinitely. Even if we change the realism settings to do so, the best we can do is maintain position however far behind, unable to catch up until the AI gets to altitude. It's really damn annoying. That's weird, because I keep up with AI during climb in many types of aircraft all the time. In many cases I keep closer to the others than the AI would if I put my plane on autopilot and let the AI fly my plane.

Name the type and I will record a track showing me keeping up and I'll send it to you. As I mentioned in my post though, there are a few types with default cruise too high, but not many. In those cases I alter the cruise by editing Europlanes.dat or Pacificplanes.dat files. It can be done though. Are you climbing too hard and slowing down too much??

NonWonderDog
04-22-2006, 12:38 PM
Keeping up isn't really the problem. If I take off as soon as possible and stay right on my wing leader's *** during what's supposed to be the formation circle, I have no problem keeping up with most planes.

If I take off in the normal pattern and expect my wing leader to circle the field before heading off (doesn't happen), I can't catch up until my wing leader levels off because he's in a maximum speed climb in his Emil.


...Actually, I haven't seen this as much recently, now that I think of it. I usually prefer DCG to DGEN, and I think there was a time when DCG didn't use plane-specific cruise speeds. I fly a lot of early-war stuff, and it's possible that the default cruise speed was just too high.

mortoma
04-22-2006, 07:14 PM
You can change cruise speeds in DCG too, by editing the class.dcg file!! Just thought I'd tell you so you know about it.

Tully__
04-22-2006, 07:44 PM
Originally posted by hi_stik:
I am aware of the discrepancy in airspeed readings because of atmospheric anomalies, but I thought the speed bar was a "true" gauge. Still, even at 365mph TAS, that's still well below the max. airspeed of the P-51. right?...
Speed bar is IAS. For TAS you have to turn off the cockpit and use the Arcade style no cockpit instrument. Turning off the cockpit requires the "Cockpit Always On" difficulty setting to be turned off and use of the "Toggle Cockpit" control (Ctrl-F1 by default).

Tully__
04-22-2006, 07:56 PM
Originally posted by joeap:
But they use the same FM right. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif http://forums.ubi.com/images/smilies/shady.gif
Same flight model. Not same damage model for some stuff. Engine overheat and pilot induced control damage (jammed flaps/undercarrige) are among the stuff they don't seem to be subject to. While it's never been mentioned, it's also possible they have a simplified engine management profile.

joeap
04-23-2006, 05:21 AM
Originally posted by Tully__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by joeap:
But they use the same FM right. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif http://forums.ubi.com/images/smilies/shady.gif
Same flight model. Not same damage model for some stuff. Engine overheat and pilot induced control damage (jammed flaps/undercarrige) are among the stuff they don't seem to be subject to. While it's never been mentioned, it's also possible they have a simplified engine management profile. </div></BLOCKQUOTE>

Well then that sounds ok, but the term is a bit misleading then IMO.

WOLFMondo
04-24-2006, 07:58 AM
The Ai definately doesn't have the same DM in regards to break up speeds. Its the one thing I wish they did because it really annoys me when a Zero follows me in a 450mph dive and doesn't break up. I sometimes think the Ai uses a different FM as well.

Treetop64
04-24-2006, 08:54 AM
The AI exibits no DM at all in regards to break-up speeds. http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif