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How do I achieve max speed?


USARStarkey

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That isn't all that close. You can just apply a percentage to it piecemeal like that dude.

 

It was just an example.

 

I'm glad to see that you've gotten a response in your bug post. Hopefully that'll get some extra eyes looking at the issue. :)

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That would be extremely interesting if you did that. It would also make no sense lol

Well, if you were able to get to 435, then you should be able to get to 441. I will say that it took a very long time to get there. I should also tell you that the power curve I observed follows verbatim the light green power curve Ive been trying to explain to you the past day. There IS a difference between those two P-51s; they ARENT the same airframe. And before you spout off that they are the same, no two aircraft are the same. Ever.


Edited by hitman
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Dude, I know they aren't the same air frame. And as I have been trying to explain to you, the light green is only a estimate. (for the 1000th time) No one here has stated that they were the same air frame. Especially since as an estimate, the light green isn't an air frame at all. And yes, I am aware that no two air frames are the same. What was stated is that There are only minor differences between the D models, none of which are of a aerodynamic or power related nature aside from the dorsal fin. Seeing as the RL test plane and the DCS plane both have dorsal fins, this is a non-issue.

By what logic would I be able to get to 441 if I can get to 435 at the same altitude? First off, I can only get to 430, not 435. Second, by that reasoning I wouldn't have any limitations on speed. If I can get to 441, why not just go to 460? Furthermore, you have yet to upload that track. And if you did get to 441 in lvl flight at 2600rpms, it would contradict your statement regarding the light green curve because it is for 3000 rpms.

 

On the issue of airframes, there would always be small differences between aircraft of good condition. BUT a 10mph difference would be indicative of something being amiss with the aircraft. Great care was taken in these tests to ensure these planes were in perfect or near perfect condition, which is why in P-51B tests the aircraft consistently achieve near-same results even with different air frames.

[sIGPIC][/sIGPIC]Weed Be gone Needed

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Small question - how are you converting your airspeed? I havent uploaded the track because its 20mb in size, and forum code here only allows for 5.

 

Are you converting the accelerometer from mph to tas? Reading the info bar in F2? Converting the number in F2 from kts to mph? I ask this because at this moment I have 66" on the manifold at 25,850 with WEP implemented. Of course, the weather I have set is at 0c @ sea level. Maybe 65.5, but apples and oranges.

 

 

(just in case you actually still believe Im lying)

http://img.photobucket.com/albums/v389/utley27/Screen_140418_165815.jpg~original

And just in case you happen to say that Im not at 441kts, Ill just get my "no shit" retort out of the way. And now that I think of it, converting the speed to tas, Im at 442.5 mph.


Edited by hitman
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F2, but also by using TACVIEW. Also, try uploading to youtube. It would take a minute though.

 

i also never said you were lying. I said that it wouldnt make any sense if you got to 442 on less than 3000rpm. Also I cant seem to make this screenshot large enough to read, and it proves nothing since I cant see if you sustained the speed. I'm not saying you did, but you could have gained speed from a small dive and you just havent drained the E yet. A video is needed to show sustained holding of the speed.


Edited by USARStarkey

[sIGPIC][/sIGPIC]Weed Be gone Needed

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F2, but also by using TACVIEW. Also, try uploading to youtube. It would take a minute though.

 

i also never said you were lying. I said that it wouldnt make any sense if you got to 442 on less than 3000rpm. Also I cant seem to make this screenshot large enough to read, and it proves nothing since I cant see if you sustained the speed. I'm not saying you did, but you could have gained speed from a small dive and you just havent drained the E yet. A video is needed to show sustained holding of the speed.

And I never accused you of calling me a liar, just...damage control, thats all.

 

Wasnt able to sustain the speed, the engine fragged itself out after about 10 minutes of being at max MAP. I have a track file for this one, and its actually a reasonable size this time. And let me explain myself how I got to that speed - the aircraft wouldnt move past a certain threshold without dropping the RPM to 2600. Youll just have to pay attention to my throttle manipulation if you care about that sort of thing, just note that I had to do it. My final RPM was 3000, though. As far as the screenshot goes, it should take you to the minimized picture on photobucket, and click on the icon to enlarge it to its max resolution on the bottom right corner of the image. Its at 5760x1080, so its...big.

 

My conversion is utilizing the following formula - TAS = IAS + 0.02 x IAS x altitude / 1,000

p-51 test.trk


Edited by hitman
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You arent on the 1.2.8 beta are you...?

 

Edit - try this yourself instead. Its impossible for me to record that track with FRAPS at my screen resolution, and I cant alter the views in fear that it will destroy the track file.

 

The mission is start off at Batumi with a 9200lb gross weight. Outside ambient temps at sea level is 0c. Season is winter, cold and dry. Climb to 25,850 and see for yourself. At 26, the MAP will steady off at 65" and sharply decrease thereafter, so that number is the sweet spot.

test test test.miz


Edited by hitman
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It would be good to know under what conditions the estimated and actual test runs were (the light and dark green lines on the chart). 0 degrees C at sea level is quite a large difference from a standard day.

 

(though now that I think about it, I don't know if a "standard day" had been defined back when that chart was made).

 

In any case: do we know what the atmospheric conditions were for the actual test that made 440-something at 26,000? There's no reason why you should consider the actual test to be "correct" unless you know what the temperature and pressure was so it can be replicated in-sim. This may be why the DCS P-51D follows the estimated/calculated curve much closer.

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This simulator doesnt simulate weather all that well. You cant adjust barometric pressure or humidity unless you just load a rainy day in the mission editor. In real life, altitude density is dependent on dew point, absolute humidity, atmospheric pressure. Basically put, the weight of the air is either going to be dense or light with the amount of moisture in the air, and thats too many variables to calculate. In DCS, its either wet or dry. To make up for that, you can choose the extremes. Naturally aspirated engines performances are very much tied into atmospheric density; kind of like how at high altitudes your car may run like a 3 pack a day smoker in the boston marathon, and in areas in low altitudes and cold weather, supercharged/turbocharged vehicles can run like Usain Bolt on crystal meth.


Edited by hitman
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and thats too many variables to calculate. In DCS, its either wet or dry.

 

No it is not. :)

 

Just because the UI doesn't account for it does not imply that it is not simulated.

Good, fast, cheap. Choose any two.

Come let's eat grandpa!

Use punctuation, save lives!

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Didnt say it wasnt simulated, said it was poorly simulated. And I daresay "poorly".

 

Then i dare say you need to get yourself up to speed because much has changed in that regard.

Good, fast, cheap. Choose any two.

Come let's eat grandpa!

Use punctuation, save lives!

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Then i dare say you need to get yourself up to speed because much has changed in that regard.

Aparrently not if I have to drop the temperature to freezing just to get a higher manifold pressure in the engine.

 

Ill let you give this a shot, and Ill take the heat if you demonstrate that it works. Load up a mission at 70f clear skies, takeoff from whatever runway, and judge how long it takes for you to get airborne in the P-51. Seconds, distance...then try those same conditions with fog on the deck. Then give it a shot with rain (100% precipitation). Keep the temps the same, the time of day the same, but just add moisture to it. You should see a HUGE difference between the three. I "havent" seen a difference with these varieties, only when increased or decreased temperatures are introduced. And to make it easier, keep your MAP in the green.


Edited by hitman
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I might have overread this but do you have data regarding the configuration in which the RL test was performed? What would be particularly interesting to know is the fuel load.


Edited by sobek

Good, fast, cheap. Choose any two.

Come let's eat grandpa!

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Would it help if i told you that humid air has actually less density than dry air?

I know this. This is why aircraft dont fly well in humid conditions. Same applies to hot environments, and why hot and humid environments are frowned upon by all pilots.

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I might have overread this but do you have data regarding the configuration in which the RL test was performed? What would be particularly interesting to know is the fuel load.

The test was approximately 9300 lbs gross weight. Non useable fuel wasnt mentioned, just aircraft weight.

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So, sobek, since your a moderator do you have the ability to get some dev attention on this. I would like to know if this is a bug or not. The original issue not what is being discussed 7 pages in.

Kinda did solve the issue here...

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Fair enough, after doing the math it looks like i underestimated the effect of humidity on performance. Seems that humidity hasn't made it's way into powerplant performance yet.

Good, fast, cheap. Choose any two.

Come let's eat grandpa!

Use punctuation, save lives!

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Fair enough, after doing the math it looks like i underestimated the effect of humidity on performance. Seems that humidity hasn't made it's way into powerplant performance yet.

Its not just powerplant, its everything. Humidity destroys lift, humidity displaces oxygen, and humidity creates drag. It is the most critical factor in weather. No simulator that Ive played with -save for the C-130J simulator here at Lockheed- even calculates it into the weather. You cant even get a decent baseline for performance in DCS because of it. You can get the same effect from dropping and raising the temperatures though, so at least its doable.

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