HeliheadDigger Posted February 4, 2020 Share Posted February 4, 2020 pls read this one diving tests of p-51 http://www.wwiiaircraftperformance.org/mustang/p-51d-dive-27-feb-45.pdf 0.85 is max what they got. I dont know what speed are we reading on p-51's speed gage maybe it is calibrates IAS After action reports are nice but those are not controlled environment for testing, it could be speed gage error. In trial tests everything is double checked and tested multiple times to make sure everything is legit. And Pilot even the best one could not tell if he going 0.8 or 0.9 mach grafspee the IAS is calibrated airspeed, when they design the pitot static system they calibrate it to provide the speed, this also compensates for altitude as the air gets thinner, Mach number is a combination of speed and altitude/temp so the speed of sound varies with altitude. The p51 has no Mach indicator, the Bell x1 post war had a variable pitch elevon controlled buy a jack screw and I think nitrogen to adjust its angle of incidence to allow the shock wave to pass over it allowing the pilot to maintain control through .85 mach .The mustang encountered the buffet and the propellor acts as a brake as the tip speed passed the sound barrier, the mustang cannot go through the sound barrier, no piston plane can, unless it's in space with a rocket up its backside. The combat reports are life and death reports, no test pilots liked to push the death side of the test, many died in the process of gaining faster than sound flight. Many WW2 pilots pushed the aircraft past designed safe limits. However if many many reports state over 600mph I believe them. They gave it all to fight for what they believed in (all sides) The results gave the americans the heads up to use elevons and push through the Mach .85 up to the sound barrier. Thin swept wings and elevons where now the jet age. Link to comment Share on other sites More sharing options...
grafspee Posted February 4, 2020 Share Posted February 4, 2020 (edited) grafspee the IAS is calibrated airspeed, when they design the pitot static system they calibrate it to provide the speed, this also compensates for altitude as the air gets thinner, Mach number is a combination of speed and altitude/temp so the speed of sound varies with altitude. The p51 has no Mach indicator, the Bell x1 post war had a variable pitch elevon controlled buy a jack screw and I think nitrogen to adjust its angle of incidence to allow the shock wave to pass over it allowing the pilot to maintain control through .85 mach .The mustang encountered the buffet and the propellor acts as a brake as the tip speed passed the sound barrier, the mustang cannot go through the sound barrier, no piston plane can, unless it's in space with a rocket up its backside. The combat reports are life and death reports, no test pilots liked to push the death side of the test, many died in the process of gaining faster than sound flight. Many WW2 pilots pushed the aircraft past designed safe limits. However if many many reports state over 600mph I believe them. They gave it all to fight for what they believed in (all sides) The results gave the americans the heads up to use elevons and push through the Mach .85 up to the sound barrier. Thin swept wings and elevons where now the jet age. Back in WW2 IAS wasn't calibrated, there are charts available for calibrations. Problem is what was the absolute limit for air frame i guess that this thing varied, one p-51 could go 550 another one maybe could hit 600 mph and another one would fall apart at 520 mph. Hard to simulate this Edited February 4, 2020 by grafspee System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
HeliheadDigger Posted February 4, 2020 Share Posted February 4, 2020 Back in WW2 IAS wasn't calibrated, there are charts available for calibrations. Problem is what was the absolute limit for air frame i guess that this thing varied, one p-51 could go 550 another one maybe could hit 600 mph and another one would fall apart at 520 mph. Hard to simulate this yes agree Simulate the pitch instability starting at 500mph below 10000 feet at 550 rip the wings off, as long as the axis planes wings come off at 530 mph we are accurate to the combat reports I am sure that the pilot was so fixated in the dive he never even saw his Airspeed anyway, Link to comment Share on other sites More sharing options...
HeliheadDigger Posted February 4, 2020 Share Posted February 4, 2020 grafspee the IAS is calibrated airspeed, when they design the pitot static system they calibrate it to provide the speed, this also compensates for altitude as the air gets thinner, Mach number is a combination of speed and altitude/temp so the speed of sound varies with altitude. The p51 has no Mach indicator, the Bell x1 post war had a variable pitch elevon controlled buy a jack screw and I think nitrogen to adjust its angle of incidence to allow the shock wave to pass over it allowing the pilot to maintain control through .85 mach .The mustang encountered the buffet and the propellor acts as a brake as the tip speed passed the sound barrier, the mustang cannot go through the sound barrier, no piston plane can, unless it's in space with a rocket up its backside. The combat reports are life and death reports, no test pilots liked to push the death side of the test, many died in the process of gaining faster than sound flight. Many WW2 pilots pushed the aircraft past designed safe limits. However if many many reports state over 600mph I believe them. They gave it all to fight for what they believed in (all sides) The results gave the americans the heads up to use elevons and push through the Mach .85 up to the sound barrier. Thin swept wings and elevons where now the jet age. Thanks for that report, i love reading that stuff. Any way test pilot are that test pilots and a large safety factor is added. But very interesting they mention the pourposing behaviour Link to comment Share on other sites More sharing options...
grafspee Posted February 4, 2020 Share Posted February 4, 2020 (edited) Another thing is combat damage in planes, we cant be 100% if this fw 190 was brand new, this plane could got some combat damage and ground crew just quickly repaired wholes w/o grand inspection of the air frame. Maybe some wing struts were damaged and not fixed properly thos weakening wing.It is really hard to model anything based on this. But i will agree that when plane has 505 mph speed limit and at 507 mph your control surfaces starting come off in crazy rate i think something was set too tight there :) Based on what test 505 limit was set i don't know, maybe wind tunnel ? Yes, test pilots are not suicidal persons, Test are set up based on calculation and some safety limits are set too, thos test reports says that they were diving straight down :) When i get back home i will post 2 screenshots from p-51's manuals representing temp/pressure limits for oil fuel and coolant there are 2 version. Getting back to DCS FW 190 D9 and BF 109 K-4 when i fly those temps are always at temp limits. Edited February 4, 2020 by grafspee System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
Ala13_ManOWar Posted February 4, 2020 Share Posted February 4, 2020 … Mach number is a combination of speed and altitude/temp so the speed of sound varies with altitude …From the pilot's theory we study, and that's an usual question in tests, Mach number only varies with temperature. S! "I went into the British Army believing that if you want peace you must prepare for war. I believe now that if you prepare for war, you get war." -- Major-General Frederick B. Maurice Link to comment Share on other sites More sharing options...
grafspee Posted February 4, 2020 Share Posted February 4, 2020 (edited) From the pilot's theory we study, and that's an usual question in tests, Mach number only varies with temperature. S! Yes, decreased pressure and density cancel them self. So temp is major factor. but air temp is kinda dependent from altitude. In cold weather temp near the ground could be lower then temp at alt so there we have small reversal :) Edited February 4, 2020 by grafspee System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
grafspee Posted February 4, 2020 Share Posted February 4, 2020 (edited) There is -7/-9A And -3 Question which one have we. Take note on increased MP for cruise from 36" to 42" at 2400 rpm and increased Oil inlet temp from 90 to 105 So by the look of gages and 36" cruise we have early version so oil desire temp are tow to tow with green arc on gages same as red line which is 90 C so i don't quite understand what yo-yo have on mind telling that actual limits are higher then those on represented on gages. Manual state the while using WEP 95C oil tem is allowed for no longer then 5 min iirc so it is a little inconsistent with new oil temp limits, or maybe oil temp limit for wep is stay unchanged. Another interesting thing from manual -7 power plant chart -9A this one is crazy 61" crit alt is 34k ft crazy Edited February 4, 2020 by grafspee System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
grafspee Posted February 4, 2020 Share Posted February 4, 2020 There is different part about fabric covered elevators and metal covered elevators looks like metal one is a little bit later in compresibility 0.76-.78 speed of sound. Which one do we have ? System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
MadCat1381 Posted February 6, 2020 Share Posted February 6, 2020 The P-51D-25 and 30 we have in DCS have metal covered elevators and the V-1650-7 engine. The only fabric covered control surface is the rudder. Link to comment Share on other sites More sharing options...
grafspee Posted February 7, 2020 Share Posted February 7, 2020 (edited) Looks like v-1650-7 has oil inlet temp 90C and -3/-9a 105C Edited February 7, 2020 by grafspee System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
HeliheadDigger Posted February 13, 2020 Share Posted February 13, 2020 Yes the 190 Dora runs hot oil in combat however I hardly ever need to look at that temp. However the P51 system should behave the same, it should not start the random failure clock when it go’s over the red line, If I open the oil cooler it’s really hard to get it to overtemp and cause this random failure mode. The Engine is now much more reliable and usually lasts the whole fuel cycle in combat manoeuvres. Unless hit by flack. Any way I’m over the P51’s cooling system, just need to stop popping engines in a casual dog fight. Open it and its fixed. Link to comment Share on other sites More sharing options...
HeliheadDigger Posted February 13, 2020 Share Posted February 13, 2020 I can see in the note that the oil temp stays in the green with auto except on hot days with high power, that means it had reached it’s thermal limit. In DCS this is not the case on AUTO. This is exactly my point. I agree the oil should get hot at low speed high power demand such as a climb in the vertical. Great work on the graphs and charts and yes Yo Yo did a great job but like all things great they don’t last forever without updates. Give us 150 octane give us 82 In manifold pressure Give us dive speeds to .85 Mach without structural damage. Oh and fix the DM because that Gov failure model is darn right stupid. P51D Cadillac of the sky. Link to comment Share on other sites More sharing options...
grafspee Posted February 13, 2020 Share Posted February 13, 2020 I can see in the note that the oil temp stays in the green with auto except on hot days with high power, that means it had reached it’s thermal limit. In DCS this is not the case on AUTO. This is exactly my point. I agree the oil should get hot at low speed high power demand such as a climb in the vertical. Great work on the graphs and charts and yes Yo Yo did a great job but like all things great they don’t last forever without updates. Give us 150 octane give us 82 In manifold pressure Give us dive speeds to .85 Mach without structural damage. Oh and fix the DM because that Gov failure model is darn right stupid. P51D Cadillac of the sky. High speed dives tests showed that at speeds above 0.8 Mach damage to plane occurred but not fatal damage :) landing gear fairings doors fail, something with guns bending mounts and ofc elevator damage. That is for sure. I fly p-51 a lot i don't pop my engine unless going for WEP. I many times climbed with full power but never ever have seen oil temp passing red line. Anyway manual is not a last word on this topic Coolant/oil doors actuators could be adjusted by ground crew to achieve better performance etc, if yo-yo is saying that optimal oil range is different then green range on gages i assume that he know something :). In case FW190 oil temp is high because i think this is outlet oil temp not inlet System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
wolfstriked Posted February 18, 2020 Share Posted February 18, 2020 I thought ED made the plane and FM of P51 but notice that OP signature says "Belsimtek/TFC Associate". I love this FM the most out of all the warbirds so whomever the superb person is who made it I would like to thank you. :) "Its easy,place the pipper on target and bombs away." :pilotfly: i7-8700k/GTX 1080ti/VKB-GladiatorPRO/VKB-T-rudder Pedals/Saitek X55 throttle Link to comment Share on other sites More sharing options...
Art-J Posted February 18, 2020 Share Posted February 18, 2020 You thought right, Yo-Yo is lead programmer for warbird FM-related things, he just didn't seem to be posting here directly all that much 8 years ago - hence, he was quoted by Bivol in original post. i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10. Link to comment Share on other sites More sharing options...
Ercoupe Posted February 18, 2020 Share Posted February 18, 2020 "In cold weather temp near the ground could be lower then temp at alt so there we have small reversal " I just noticed this quote from Graf Spee. As a real life pilot since the mid 1970's, I have never experienced this. The air temperature drops 2 degrees for every thousand foot of altitude. I've never seen it colder on the ground then at altitude. Link to comment Share on other sites More sharing options...
grafspee Posted February 18, 2020 Share Posted February 18, 2020 (edited) "In cold weather temp near the ground could be lower then temp at alt so there we have small reversal " I just noticed this quote from Graf Spee. As a real life pilot since the mid 1970's, I have never experienced this. The air temperature drops 2 degrees for every thousand foot of altitude. I've never seen it colder on the ground then at altitude. I quoted it from P-51 or p-47 manual. Argue with them. Edited February 18, 2020 by grafspee System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
Art-J Posted February 18, 2020 Share Posted February 18, 2020 Temp inversions are quite normal thing in meteorology, and there are quite a few variants of them. Granted, most often in the vicinity of incoming warm fronts and at low-to-mid altitudes, but still. Ercoupe, you must have been flying in a very specific geographic region then. Even If you haven't encountered them (which I doubt), you surely read about them, as they're mentioned in every basic aero meteorology handbook out there. i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10. Link to comment Share on other sites More sharing options...
ED Team Yo-Yo Posted February 19, 2020 ED Team Share Posted February 19, 2020 High speed dives tests showed that at speeds above 0.8 Mach damage to plane occurred but not fatal damage :) landing gear fairings doors fail, something with guns bending mounts and ofc elevator damage. That is for sure. I fly p-51 a lot i don't pop my engine unless going for WEP. If you used WEP, for 5 and more minutes your best choice is to set 46/2700 regardless of the frags you want to add to your score. Try this advice... :) Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles. Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me Link to comment Share on other sites More sharing options...
grafspee Posted February 19, 2020 Share Posted February 19, 2020 If you used WEP, for 5 and more minutes your best choice is to set 46/2700 regardless of the frags you want to add to your score. Try this advice... :) I don't use WEP in offensive, I use WEP only in situation w/o other exit and i keep WEP on until all foes are clear of my tail :) System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
ED Team Yo-Yo Posted February 19, 2020 ED Team Share Posted February 19, 2020 I don't use WEP in offensive, I use WEP only in situation w/o other exit and i keep WEP on until all foes are clear of my tail :) Anyway, the less you load the engine after WEP the longer you go. Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles. Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me Link to comment Share on other sites More sharing options...
grafspee Posted February 19, 2020 Share Posted February 19, 2020 (edited) Anyway, the less you load the engine after WEP the longer you go. Why WEP use would nail fate of the engine, and only you can do is stretch its dying time ? Manual says nothing about, after WEP use decrease power to the lowest possible and imidietly RTB and pray, so engine last long enough to get you home. Edited February 19, 2020 by grafspee System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
zcrazyx Posted February 19, 2020 Share Posted February 19, 2020 Temp inversions are quite normal thing in meteorology, and there are quite a few variants of them. Granted, most often in the vicinity of incoming warm fronts and at low-to-mid altitudes, but still. Ercoupe, you must have been flying in a very specific geographic region then. Even If you haven't encountered them (which I doubt), you surely read about them, as they're mentioned in every basic aero meteorology handbook out there. its interesting most people dont know about it, in the UK at least fog gets trapped all the time and it can colder on the deck, another interesting inversion can be when scuba diving, its not uncommon that you can dive deeper and go through many different temperature zones both warmer and colder. it feels rather strange. Link to comment Share on other sites More sharing options...
grafspee Posted February 19, 2020 Share Posted February 19, 2020 its interesting most people dont know about it, in the UK at least fog gets trapped all the time and it can colder on the deck, another interesting inversion can be when scuba diving, its not uncommon that you can dive deeper and go through many different temperature zones both warmer and colder. it feels rather strange. I will say better even in the fridge you have temp inversion where at the bottom is colder and at top is warmer ha :) System specs: I7 14700KF, Gigabyte Z790 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
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