Bremspropeller Posted September 26, 2021 Posted September 26, 2021 3 hours ago, ACG_Cass said: Do you think the A3 should should be able to out sustain a 109 that's ~25% lighter, has slats and a better lift coefficient? If a difference of 0.3s after one time around the circle is "out-rating" to you, then congratulations - you're a much better pilot than I am. On top, while being "out-rated", the 109 will fly a tighter radius turn, being 10kph slower. The A-3 has ~20% more installed power than a contemporary 109G. It's not that much about lift-coefficient, but L/D and excess-power. Is the A-3 really the outlier? It would be interesting to have @Floppy_Sock or @Holtzauge run the numbers on the Fw 190s we have in game, concerning max sustained and max instantaneous rates. Following the game-numbers, the A-5/ A-6 is a whopping 7.5s (14%) worse than the A-3, while being only 3% (4% for the A-6) heavier with better cowling-drag properties due to the refined cooling-grills. The A-8 is 7% heavier. All talking OEW. A-3: 2845kg OEW / 3855kg MTOW A-5: 2960kg OEW / 4106kg MTOW => 115kg weight creep A-6: 2998kg OEW / 4186kg MTOW => 38kg weight creep (153kg over the A-3) A-8: 3050kg OEW / *4392kg MTOW => 52kg weight creep (205kg over the A-3, seems like that doesn't include the aux fuel tank, so the figure is higher on the game A-8) ___ *(including 115l aux fuel tank)
-=PHX=-SuperEtendard Posted September 27, 2021 Posted September 27, 2021 I wouldn't trust the stat cards in regards to turn times, I have seen that you can get lower results overall. A-5 is listed at 23.5s sea level at 280 km/h IAS with full power for standard weight (full internal fuel stock armament). But flying it myself I got around 20.6 seconds turn time on average with it. 1 1
JtD Posted September 27, 2021 Posted September 27, 2021 The weight creep between the A- and the A-5 is mostly due to the two extra 20mm cannons in the A-5. Armament options, essentially. The Fw190 turned pretty well in game when I last tested it, much better than the stats card say. It's more difficult to fly at the limit that the 109 is, though. I consider the Fw190 family turning to be a bit optimistic, but not unrealistc. 1 2
CountZero Posted September 27, 2021 Posted September 27, 2021 (edited) this is turn times i go by when i wont to know what player can do ( what they have in specs i belive is just how ai is suposed to turn ) from JtD tests 2018, dont know if there is more up to data one Edited September 27, 2021 by CountZero 1
Cpt_Siddy Posted September 27, 2021 Posted September 27, 2021 Is it at all possible that the 109 and 190 is overdone in their instantaneous turn rate at high speed and the 47 is more or less correct?` The FM's that were done in earlier stages of IL2 development are bound to be prone to more errors than newer ones that are done by devs with accumulated experience? And the redoing of the old models are too much of a hassle? Remember how La-5 and 190 were total beast at 9km? Overlooked things like that tend to crop up in older FM's and are absent in newer FM's
ACG_Cass Posted September 27, 2021 Posted September 27, 2021 3 hours ago, Cpt_Siddy said: Is it at all possible that the 109 and 190 is overdone in their instantaneous turn rate at high speed and the 47 is more or less correct?` The issue is the stick forces. According to sources the P47 should have lighter stick forces than the P51, yet in game it requires much more stick movement to produce the same G at the same speed. I think that's the only thing that's incorrect in terms of the FM from an IL2 perspective (within the boundaries of IL2 modelling, obviously there will be other things that might be incorrect). @Bremspropeller It sounds like the technical information isn't always entirely correct so we're arguing over a bit of a moot point. I'd only say that there seems to be much more parity between the A8, A5 & A6 than the A3. Considering the A3 was built a long time before these I'd wager the latter aircraft are going to be more accurate.
357th_KW Posted September 29, 2021 Posted September 29, 2021 On 9/27/2021 at 1:22 PM, ACG_Cass said: The issue is the stick forces. According to sources the P47 should have lighter stick forces than the P51, yet in game it requires much more stick movement to produce the same G at the same speed. I think that's the only thing that's incorrect in terms of the FM from an IL2 perspective (within the boundaries of IL2 modelling, obviously there will be other things that might be incorrect). @Bremspropeller It sounds like the technical information isn't always entirely correct so we're arguing over a bit of a moot point. I'd only say that there seems to be much more parity between the A8, A5 & A6 than the A3. Considering the A3 was built a long time before these I'd wager the latter aircraft are going to be more accurate. I'd be very cautious relying on that report from Sport Aviation, as it was done long after the war with modified and restored aircraft. In the case of the P-51 in that article, the results they got differ wildly from what was recorded in period tests. On 9/24/2021 at 5:34 PM, MrRistro said: I found this 1953 NACA report detailing the flight characteristics of a F-47D-30 (post 1947 designation of the P-47D-30) but it is written in a way that I have trouble understanding it. If you understand the technical jargon in this report, feel free to chime in. Page 44-47 (figures 22-23) appear to contain the stick force vs G curves for varying speeds, altitudes and CG loadings. 1
Legioneod Posted September 29, 2021 Posted September 29, 2021 On 9/25/2021 at 6:34 PM, LR.TheRedPanda said: Me and Cass have tested the two planes in sustained turning a while back and found what you said to be true in game. Where it falls flat is in the instantaneous turns which is a night and day difference between the two. The 190 has a huge edge over the 47 in this regard. The sources above highlight the aircraft having quite a few instabilities and being very responsive to pitch with light stick forces. With the second FM revision came a change where they wanted to make the plane "feel" heavy with a sense of weight/ rotational inertia making it feel sluggish like a small bomber. Perhaps another inspection could be done to rectify this issue. Most pilot accounts that I have read say the P-47 felt light on the controls and you had no sense that you were flying a huge heavy aircraft. It felt lightweight to most pilots from the accounts I've read. On 9/25/2021 at 8:06 PM, BraveSirRobin said: A P-47 warbird pilot has “flown“ the BoX P-47. He says it is “spot on”. The problem is that he, and many of the people who play this game, don’t fly it at the altitude where most of the P-47 aces were created. It’s a pig down low, as it should be. One thing the keep in mind is that modern warbird pilots don't fly anywhere near max performance that the WW2 guys did. His perception of the aircraft can be correct for the airshow speeds/power that he flew at but it doesn't hold much weight when judging max performance. The are some speed/power inaccuracies in the P-47 already so I'm sure there is the possibility that other things need looking at as well. One thing I do know is that coming from DCS P-47 to IL2 you can notice a huge difference. DCS feels like it actually has power and can do some decent maneuvers with speed but then IL2 it just feels like a whale that can't do much, you certainly don't have that sense of power or maneuverability that you do in DCS. The P-47 isn't a P-51 of course but that doesn't mean its maneuvering was terrible, it was average overall, but you don't really get this feeling in game. Overall the DCS P-47 is the superior version imo. Il2 does great work and I do like most of the aircraft they put out, but when it comes to the P-47 DCS has the better version. For those interested in the Power vs Altitude problems with the P-47. 1 3
Yak_Panther Posted October 2, 2021 Posted October 2, 2021 I dug through the NASA technical reports about the P-47. Based upon my research the lift coefficient for the P-47 game looks low, the elevator's effectiveness, (ability to generate pitch rate), and the increased loss of elevator effectiveness due to air speed / mach effect is too high. In short, The P-47 it should be more responsive to initial pitch inputs. I will explain each issue in detail below. CL Max The Cl max, in the game, is probably low. It’s currently 1.2 according to the game info. Based on NACA reports the power on Cl max of the P-47 is around 1.4 - 1.5. NACA-ACR-L4127 https://ntrs.nasa.gov/citations/19930092728 I will discuss the lift issue in greater detail, after discussing the handling qualities of the aircraft. The issues related with handling qualities of the aircraft and the mach effects are as Follows: A. The stick forces are too high and the elevator effectiveness is too low. In general the Elevators are not effective enough at generating pitch moments. The aircraft should generate greater amounts of pitch rate per unit of joystick input. The service Cg of the P-47 varies from 27% MAC to over 30%. This helps to reduce the stick forces per G. NACA TN 2899 Provides the stick forces per G for the P-47. At low altitudes, the stick forces per G vary from 7.5 lbs per g at mach .59 to, 5.5 lbs per G at mach .3 https://ntrs.nasa.gov/citations/19930083857 The scale lines are preserved on the older version of this report. NACA L8A06 https://ntrs.nasa.gov/citations/20090022749 Though the stick forces are high for the era. They are not beyond the capabilities of a human. The stick force per G on the P-47, are similar too the stick forces per G onthe F/A-18. Which is ~ 6 lbs per G at high G. https://apps.dtic.mil/sti/pdfs/ADP002709.pdf NACA TN 2899 also shows the Coefficient of Normal forces per degree of elevator angle. And the Normal Force Coefficient generated per degree of Elevator angle. The aircraft is capable of generating large forces with only 4 degrees of elevator angle, Given the elevator is capable of moving to up to 30 degrees trailing edge up. It appears to be effective and well sized. In game the elevator requires almost full deflection to generate pitch rates at speeds near 300 mph at sea level. So the game appears to under-represented how effective the elevators are. Based on these reports, the P-47 should feel more responsive to inputs. Closer to the response of a Typhoon than a bulldozer. Issue B: The loss of elevator control / increase in stick force due to mach effects; These appear to be to high and lead to handling deficiencies throughout the flight envelope. This compounds the general lack of elevator effectiveness, because the mach effects are also applied at too low of an airspeed speed, and altitude. NACA ACR 5D20. Shows the pitch down moment should only occur at Mach greater than .78 https://ntrs.nasa.gov/citations/20150011311 NACA report 5D19, https://ntrs.nasa.gov/citations/20150019985 The uncontrollable nose down moment is not the result of the elevator losing the ability to generate pitch up moments. The primary reason for nose down moment at high mach on the P-47 is the change in lift curve slope resulting in an increase in static stability, coupled with a decrease in lift coefficient required for trim. NACA 3k18 https://ntrs.nasa.gov/citations/19930092521 NACA RM A7F09 A Summary and Analysis of Data on Dive-recovery Flaps https://ntrs.nasa.gov/citations/19930085641 NACA 5D19 https://ntrs.nasa.gov/citations/20150019985 The lack of control above mach .78 is not the result of increased air loads leading to higher hinge moments on the elevator, It’s not a stick force issue. The aircraft should be able to generate high pitch rates even at high airspeeds below Mach .78 NACA 5D20 shows that below mach .78 the elevators are capable of generating pitching moments, without excessive hinge moments. https://ntrs.nasa.gov/citations/20150011311 The nose down tendency from the increased stability due to mach effects, simply over powers the tails ability to trim. At Cl’s greater than .2; The pitch down moment due to the mach effect,at mach .79, are greater than the pitch up moment which can be generated by the elevators. It’s not that the tail becomes unmovable at high mach. Which Is why the primary effect of the dive is to change is to increase the lift coefficient, there by changing the angle of attack need needed to maintain constant lift. From NACA ACR 5D19. https://ntrs.nasa.gov/citations/20150019985 The mach effects seem to be modeled by a decrease in elevator efficiency, eg a loss of pitch rate due to airspeed, ect. When this loss of efficiency is done below mach .78 and coupled with general lack of efficiency of the elevator the result is an aircraft which responds poorly to inputs. The Lift Issue In Detail. The Cl Max of in game P-47 probably too low. It is ~ 1.2, based on the in game technical info Weight 11,385 lbs, stall speed of 111 mph, the wing area is 300 square feet. Flight tests at a gross weight of 12 565 lbs, put the stall speed at 105 mph, power off. http://www.wwiiaircraftperformance.org/p-47/P-47B_41-5902_PHQ-M-19-1417-A.pdf With the instrument correction you applied. The Cl max works out ~1.35 to 1.4 https://reports.aerade.cranfield.ac.uk/handle/1826.2/3148 A power off Cl max of 1.35 to 1.4 agrees with the NACA High Speed Wind Tunnel Tests of the 30% Scale Model of the P-47, NACA ACR 5D30. Which puts the Power Off Cl Max at 1.4 https://ntrs.nasa.gov/api/citations/20150011311/downloads/document-2_Redacted.pdf Various full scale flight tests give a power on Cl max of 1.4 to 1.5. NACA TN 1734 compares The flight test Power on CL max of the aircraft to scale model. It Puts The Cl max of Aircraft at 1.5 Mach .4 It’s further broken out in a chart. https://ntrs.nasa.gov/api/citations/19930082429/downloads/19930082429.pdf The testing was carried out As a part of NACA ACR L4I927. Correlation of Flight Data on Limit Pressure Coefficients and Their Relation to High-Speed Burbling and Critical Tail Loads. https://ntrs.nasa.gov/citations/19930092728 Which also provides sectional lift coefficients. And Calculated V-N diagrams for two different wing loadings 40 lbs per sq feet. ~ 12,000 lbs gross weight. And for a wing loading of 30 pounds per square foot. ~ 9000 lbs gross weight. https://ntrs.nasa.gov/citations/19930092728 The a 1.4 to 1.5 lift coefficient for the aircraft is not surprising. The Republic S-3 airfoil is a derivative of the NACA 23000 series. https://ntrs.nasa.gov/citations/19930093001 The P-47’s wing tapers from a Modified NACA 23015 at the root to a 23009 at the tip. https://ntrs.nasa.gov/api/citations/19930085641/downloads/19930085641.pdf At mid chord the pressure distribution is similar to a NACA 23011 https://ntrs.nasa.gov/citations/19930092751 I’ve plotted the 2-d lift Polar of the NACA 23011 in xfoil at the stall conditions given in the flight test. http://www.wwiiaircraftperformance.org/p-47/P-47B_41-5902_PHQ-M-19-1417-A.pdf It comes out to about 1.8 .Given the way Cl max from a 2d airfoil to an actual aircraft. At 20 % reduction in lift going from a 2d airfoil to an aircraft is reasonable. https://web.mit.edu/drela/Public/web/xfoil/ A power on Cl max of 1.5 is reasonable for this aircraft. Given the size of the wing, weight of the P-47 and the year it was designed; 1 19 8
LuftManu Posted October 2, 2021 Posted October 2, 2021 23 minutes ago, Yak_Panther said: I dug through the NASA technical reports about the P-47... Excellent. I hope @AnPetrovich takes a look at this info. Looks really helpful to make our Thunderbolt more accurate. 5
FTC_Cule Posted October 2, 2021 Posted October 2, 2021 (edited) Great research! In terms of implementation, I do not know how the aircraft is modelled from a technical perspective. The compressibility effects are probably a linear or exponential or polinomial model, which is not too difficult to tweak. The lift side of things is a little more complicated. I would imagine a relatively easy way to address this issue would be to change the CLalpha of the tail. It needs to be increased to reflect the larger authority per pitch position. Stick forces prevent deflection. If there is deflection, the forces have been overcome already, and if the aircraft is not pitching, it's the fault of the authority of this control, not the overcoming stick forces. CLalpha for the tail should be composed of the CL0, CLdE (deflection of elevator), and many other contributions from derivatives, coupling phenomenon and geometry. The CLdE would need addressing for this particular change. Increasing CLalpha of the tail would immediately affect CLq for the entire plane. Just to clarify, q is the angular velocity due to the longitudinal pitch angle change which is what is hypothetically understated in the game. From Napolitano (or you'll find this equation on any book with basic acceptable flight mechanics simplifications): Of course, a change in CLalpha_tail and CLq will have a massive effect on many aspects of the flight model, mainly responsiveness, trimming conditions and stall conditions. But if the flight model is accurately done using the 'conventional' longitudinal and lateral-directional derivatives, stability, etc.. this should not have many negative side effects, and those would be predictable and easy to counter if not desired. This is pure speculation from an aerospace engineer. I don't know the technicalities of the flight model. They should use these coefficients and the established flight mechanic laws, but it may not actually be the case. Flight mechanics can get really mathematically complicated. All flight simulators simplify to some extent. And thereby changing not only the physical laws but also the amount of specific coefficients and degrees of freedom involved. Quote It comes out to about 1.8 .Given the way Cl max from a 2d airfoil to an actual aircraft. At 20 % reduction in lift going from a 2d airfoil to an aircraft is reasonable. This is something bold, it is a loose hypothesis, which contrasts with the well detailed results on the rest of your research. The AR of P-47 is not high. The oswald factor is not so good either. The fuselage contribution to lift is significant. To make a statement of this sort one should calculate all the geometrical aspects and run an empirical model on it, and even then, you have to compute downwash into it. Or run it in CFD. I have over the years prepared a CL calculator using the biot-savart mathematical model. I will try it with the P-47 in some days. Edited October 2, 2021 by FTC_Cule 2
ZachariasX Posted October 2, 2021 Posted October 2, 2021 Stated clean stall speed of the P-47 with 12'500 lbs weight is 113 mph IAS (P-47D23). If I was to take that as TAS, I get a Clmax of 1.27. If I add PEC, it further lowers Clmax. All down for landing @ stated 100 mph stall, I get Clmax 1.6. Is there really someone here seriously arguing for a 104 mph stall speed in clean configuration that would be a result of Clmax 1.5, about 9 mph less that stated IAS stall speed? 1
Yak_Panther Posted October 2, 2021 Posted October 2, 2021 51 minutes ago, ZachariasX said: Stated clean stall speed of the P-47 with 12'500 lbs weight is 113 mph IAS (P-47D23). If I was to take that as TAS, I get a Clmax of 1.27. If I add PEC, it further lowers Clmax. All down for landing @ stated 100 mph stall, I get Clmax 1.6. Is there really someone here seriously arguing for a 104 mph stall speed in clean configuration that would be a result of Clmax 1.5, about 9 mph less that stated IAS stall speed? The speeds listed in the in game info are EAS same with the info bar.
ZachariasX Posted October 2, 2021 Posted October 2, 2021 1 hour ago, Yak_Panther said: The speeds listed in the in game info are EAS same with the info bar. I would take those with a grain of salt. I am not entirely sure how they come up with those numbers, but I suppose it is their „robot pilot“ that gives these data after they tuned the FM to match whatever they had as original source data. I cannot explain otherwise how they would come up with that range of stall speeds if it wouldn‘t correlate to in-game loadouts. If that were the case, then we‘d look at an artifact of an artifact (that is actually useful for the purpose of the game). The numbers I quoted I have as „hard data“ (whatever that means) for the plane in that exact configuration. The problem I see with my calculation is that I generally overstate actual values due to IAS getting rather short of TAS near stall speed. But as a shot in the dark, it usually points to where some truth might be. I do like (and appreciate) your collection of data. But I also do trust PN values that are put there for good reason. 1
unreasonable Posted October 3, 2021 Posted October 3, 2021 (edited) 11 hours ago, ZachariasX said: Stated clean stall speed of the P-47 with 12'500 lbs weight is 113 mph IAS (P-47D23). If I was to take that as TAS, I get a Clmax of 1.27. If I add PEC, it further lowers Clmax. All down for landing @ stated 100 mph stall, I get Clmax 1.6. Is there really someone here seriously arguing for a 104 mph stall speed in clean configuration that would be a result of Clmax 1.5, about 9 mph less that stated IAS stall speed? Yes that is what is being argued, which is an extraordinary claim. The game speeds are EAS, the trouble is - as always in these discussions - the correction that has to be applied to get to/from the IAS in the reports. The fact is that we do not get PECs in PNs at or anywhere close to stall speed, and the idea that you can make a straight line projection from the speeds that are shown is at best unproven and at worst wrong. The variation in the error with changing AoA should not be a straight line especially at higher AoA. Then 2-3 mph difference makes a big impact on the calculated CLmax, so you can easily get nonsensical results. As you say, to get a CLmax for the plane in the order of 1.4 you have to have a -ve PEC of ~ -12 kph which would be a bizarre outlier. Edited October 3, 2021 by unreasonable
ZachariasX Posted October 3, 2021 Posted October 3, 2021 (edited) What we have here is: […] D. Stalling Speeds Stalling speeds are given in the following table. Wing Flaps Landing Gear Shutters Power IAS MPH* Up Up Closed Idling 116 Up Up Open Idling 116 Up Down Closed Idling 114 1/4 Down Closed Idling 109 1/2 Down Closed Idling 105 3/4 Down Closed Idling 101 Full Down Closed Idling 98 Up Down Closed Idling 114 Up Down Open 35" Hg. 2200 RPM 107 Up Up Open 45" Hg. 2550 RPM 103 Up Up Open 35" Hg. 2200 RPM 106 Up Down Open 45" Hg. 2550 RPM 104 Up Down Open 35" Hg. 2200 RPM 107 *This speed is the ship's uncorrected indicator speed, and is effected by attitude of airplane and balance of airspeed lines. […] Which is in line with the data I gathered before. I think a Clmax of around 1.3 could be plausible, as the tests are certainly not at sea level and assuming a good pitot arrangement. Edited October 3, 2021 by ZachariasX
unreasonable Posted October 3, 2021 Posted October 3, 2021 (edited) 116mph Idling at 13,230lbs with a +3mph correction = EAS 119mph Clmax = 1.21 just as the game models the low weight/speed combination. The problem being that there are a variety of test results out there which can give a wide range of results. (Hellcat is even worse). (1.30 is already the number in the game for the D-22 at take off weight. I do not know why or if there should be significant differences in the low weight/high weight Clmax numbers. (Effects of external ordnance?) The P-47s PECs are unusual compared to the RAF planes in that they add to IAS rather than subtracting in the high speed range: (assuming this is not an error at the printer! ) However you look at that line it is hard to see a negative PEC at ~100 mph. Compare to Tempest - other UK models are similar, see chart. Taking the ratio of CAS/IAS at the lowest data point to determine the extrapolation gives a PEC at 100 mph of ~ +3mph but is it a straight line or a curve? What this forum needs to get closer to the truth on these issues is not more aeronautical engineers but an analogue instrument maker! Not sure that increasing the Clmax would make the pilots very much happier though, as I suspect it is the rather low critical AoA which is creating many of the difficulties. Edited October 3, 2021 by unreasonable 1
FTC_Cule Posted October 3, 2021 Posted October 3, 2021 (edited) There should be nobody requesting a higher CLmax. CLmax is one of the easiest things to calculate because it involves all known constants. If a NACA report says it should have a CLmax of 1.6, but you do the calculation and find out it should stall at <100mph, it will ring some bells, and it's probably because testing conditions were different and/or it was a theoretical study and/or prop hanging was involved. Alas. It's very easy to have variance in that depending on how you conduct the experiments. CLmax has little to do with elevator authority talked about earlier. Edited October 3, 2021 by FTC_Cule 1
unreasonable Posted October 3, 2021 Posted October 3, 2021 (edited) That is the trouble, it does not involve all known constants. Clmax is based on TAS, which we almost never know for sure, since published PECs from manuals never go down close to stall speeds: that is not what they were for. The RAE tests on the 109E and a NACA test on the Spitfire were the only sources I can recall from this era that attempted to estimate TAS at stall speed by using trailing pitot installations, (and IIRC they did not agree with one another!) They may be a couple of reports out there somewhere, but so far not to be seen in the forum. Since the speed is squared, errors here make a big difference to the result, and we know that instrument errors at high AoA can be significant, but we do not know what they are. You only have to look at how difficult it has been for the developers to get the CLmax even remotely right for the Tempest to see that this is a very grey area indeed. I am not lobbying for any particular P-47 CLmax BTW, just noticing that the game's current implementation is within the reasonable range. Edited October 3, 2021 by unreasonable 2
FTC_Cule Posted October 3, 2021 Posted October 3, 2021 You don't know TAS but you know it doesn't deviate too much from IAS, not enough to cause CLmax to change by over 20% its value. In any case for finetuning. By the way. CLmax should not just be obtained with stall speed... There's other highly accurate theoretical approaches to compare. And then you have CFD if you want to go DCS level.
ZachariasX Posted October 3, 2021 Posted October 3, 2021 3 hours ago, FTC_Cule said: By the way. CLmax should not just be obtained with stall speed... That is clear, but we have what we have. But it will do to sanity chack an assumption. And whatever DCS may come up with, their bird better stall at 115 mph.
unreasonable Posted October 3, 2021 Posted October 3, 2021 (edited) Just now, FTC_Cule said: You don't know TAS but you know it doesn't deviate too much from IAS, not enough to cause CLmax to change by over 20% its value. In any case for finetuning. By the way. CLmax should not just be obtained with stall speed... There's other highly accurate theoretical approaches to compare. And then you have CFD if you want to go DCS level. TAS may not deviate from IAS too much in percentage terms over most of the flight envelope, but it often does at slow speeds with high AoA. Take the RAE generic curve in the graph above: it has a speed correction of well over 20% for the lowest speeds. The RAE report on the Bf109E included the following table: That shows a +20.5 mph measured cockpit instrument error (+27% of the ASI) used to calculate the Vi for a CLmax of 1.4 (1.38 rounded up) If the original 75 mph was used instead, the CLmax would be 2.2 Using uncorrected stall speeds from tests or manuals very often gives plane CLmax well in excess of that of the airfoils. Edited October 3, 2021 by unreasonable
Yak_Panther Posted October 4, 2021 Posted October 4, 2021 Using the aircraft’s indicated airspeed as the sole basis for determining the maximum lift coefficient is problematic. So is trying to derive it, based on the slope of the correction, because the instrument corrections can also become nonlinear at low airspeeds. Due to instrument mechanics and probe position. Below is the instrument correction for the F6F Hellcat. As derived from flight testing, a trailing instrument probe was used to compute the corrections. To derive the maximum lift coefficient we should use a variety of sources . Ideally would be a full scale wind tunnel test with aircraft in service condition. Next best, would be flight tests whose purpose was to determine the maximum lift coefficient. Optimally these tests should also be conducted with an instrument package more accurate than the aircraft’s. This type of data is available. An inflight test of the P-47, with an instrument package, to determine the maximum lift coefficient of the aircraft at various Mach was conducted and is available. NACA L4I27 https://ntrs.nasa.gov/citations/19930092728 One of the purpose of this test was to determine effect of Mach on the maximum lift coefficient of the P-47 I cited this Report in my first post. The authors took the time to apply the appropriate corrections in their calculations of the lift coefficient. .The Cl max from these flight test at 15,000 feet mach .27 was 1.8 A second sets were conducted to measure the pressure distribution over the wing. A second set of Cl max’s were derived from pressure measurements taken over the wing. The two test were compared. In a second chart. The Cl max was around 1.7 at Mach .3 Let’s not be satisfied with one test, and see if there is more data which will tell us about the Cl max of the aircraft. There are wind tunnel test of the scale model of P-47. These test show a Cl max of 1.4 at an angle of attack at 15 mach .2 Let’s look at some other test of the era and see if they can give us any insight into what the Cl max should be. NACA report 792, measured tail load of the aircraft at Cl Max / Max G The airplane weighed 11,900 lbs ti 12,000 lbs, The test were conducted at 6000 feet. The stall was 4.5 G at 212 mph. Which yields a Cl max of 1.58 to 1.49 https://ntrs.nasa.gov/api/citations/19930091869/downloads/19930091869.pdf Then We have “Analysis of the Aerodynamic Design of the P-47B Airplane.” Which describes the aerodynamic evolution of the aircraft and the wind tunnel testing carried out at Langley. This report cites the Cl Max of P-47 model was 1.63 https://ntrs.nasa.gov/api/citations/20150014120/downloads/20150014120_Redacted.pdf All this data plus stall test, seems to put the Cl max of the aircraft in power off at around 1.4 and the power on Cl 1.5 to 1.6. Let’s expand our sanity check to other aircraft with similar wing profiles. The F6F uses similar airfoils. A modified 23015 tapering to a 23009. https://reports.aerade.cranfield.ac.uk/handle/1826.2/3510 Based airspeed from the trailing probe, the Cl max of the Hellcat is power off is 1.64 The results of the previous NACA testing of the P-47 are within reason for what is achievable with this wing form. The P-47 numbers are slightly higher though. Is there anything special about this aircraft that could yield the slightly higher Cl max? Yes there is; “Analysis of the Aerodynamic Design of the P-47B Airplane.” shows us the designers spent the time to minimize the airflow interference between the fuselage and the wing roots. One of design features unique for the P-47 is the fuselage taper. The fuselage does not taper until behind the trailing edge of the wing. This would increase the lift and lower drag, despite the increase to wetted area. When we look at all the data combine, it becomes clear that Clmax for this aircraft is from 1.4 to 1.6. 2 10
JtD Posted October 4, 2021 Posted October 4, 2021 Are you aware that stalls from abrupt pull ups always give significantly higher cl's then progressive stalls? The perceptible stall at 25k feet came at a clmax of 1.0, yet the abrupt one came at more than 1.6 (in your first chart), just as one example. There are worlds between these two data points. The P-47 used a Repbulic special airfoil, which is not a 23000 series NACA airfoil. All direct comparisons of calculations and wind tunnel data I recall seeing showed a slightly lower clmax for the Republic airfoil. 1 1
ZachariasX Posted October 4, 2021 Posted October 4, 2021 That is interesting data. But yet (as laymen) I am careful what to make of that. NACA 230 series airfoils have all a Clmax of about 1.5 to 1.6. These are values for infinite span, 2D profiles and on the aircraft you typically get 1.35 or so because neither build quality nor span is infinite. Anything deviating from these values better have a very good explanation. Now, the numbers you posted push that number up incredibly. It basically turns the flaps up aircraft into a flaps down aircraft. I am especially puzzled by this, as it is on of the few hard data that can directly be compared against: 2 hours ago, Yak_Panther said: The stall was 4.5 G at 212 mph. Which yields a Cl max of 1.58 to 1.49 The Sea Fury at the hands of Mikael Carlson starts burbling (200 kias, 4 g) at a Clmax of about 1.23. This is very much in line with a Clmax we get from the stated stall speed. Now, the P-47 is supposedly not just better here, it‘s a whole different sport. The Hellcat seems to be like that too according to some reports. What does that mean for other NACA 230 series aircraft, like the Fw190? (We have been there before…) Also, what does our dear sim make of lift at different speeds and altitude? Did you try to reproduce the high speed stall experiment quoted above? I might add that I don‘t want to be dismissive of your data. It‘s just that they don‘t add up (at least for me) so far. I do have some minor gripes with this and that sim engine in general that go in the direction of your argument, but I wouldn‘t go as far as making it plane specific like that. 2
E69_geramos109 Posted October 4, 2021 Posted October 4, 2021 @Yak_Panther Did you have any info or tested the turn rate of the P47 at very low speeds? With flaps it is amacing how it can turn. I would like to hear your analysis about that to see how correct is the behave of the plane also at low speeds. Thanks
BCI-Nazgul Posted October 6, 2021 Posted October 6, 2021 On 9/24/2021 at 5:34 PM, MrRistro said: I understand that the P-47 flight model had an overhaul when the D-22 came out, but I still feel the plane that produced the top U.S. aces in Europe has not been done justice. In this post I will testing using a P-47D-28 with 50% fuel and the only modification being 150 octane. Overall, going from games such as DCS to IL-2, I notice a substantial drop in maneuverability. Flight characteristics I feel are incorrect include elevator authority at high speeds, dive characteristics, and stall characteristics. Watching Greg's 1 hour and 15-minute video on the P-47's maneuverability leads me to feel DCS is far more in the right. Elevator Authority at High Speeds: In my opinion this is the primary factor leading to the lack of effectiveness of the P-47. Even with the stick all the way back and at ample speeds (315 mph+ IAS), I could not get the aircraft to the turn rate I wanted. During testing, at no point was I able to reach 7 Gs. I was either being affected by compression (will be touched on), going too slow to reach 7 Gs without stalling, or simply not being able to get the desired rate of turn. With other aircraft such as the Fw 190A-8 and even the P-40E-1, I had no issue reaching 8 Gs. Yet the P-47 seems incapable of using its speed. As a result of its limited elevator authority, the P-47 is unable to reach its best instantaneous turn rate and severely hampers one of its best aspects of its maneuverability. I couldn’t find any documentation stating the P-47 lacked elevator authority. The British testing a P-47C with 2000 hp stated “elevator control is good and always positive” when the fuel in the rear auxiliary tank had been used.This link which copied an article written by the Chief Technical Publications of Republic Aviation Corporation states its elevators had a max deflection of + 30° to - 20° which seems to be inline with a lot of aircraft designs and considering their size, I don’t understand why I run out of elevator. I found this 1953 NACA report detailing the flight characteristics of a F-47D-30 (post 1947 designation of the P-47D-30) but it is written in a way that I have trouble understanding it. If you understand the technical jargon in this report, feel free to chime in. Dive Characteristics: There are a few issues I’ve noticed with the P-47s dive characteristics. The main one being, it seems the P-47 hits compressibility at noticeably lower speeds than it should. At 20,000 ft the number where I lose complete elevator control is ~400 mph IAS and at 10,000 it is ~475 mph IAS. In that same report from the British testing the P-47C, they noted they hit its limit at 450 mph at 20,000 and 520 mph at 10,000. In the P-47’s pilot manual it lists the do not exceed speed of 500 mph IAS, but I imagine this is due to the designers not wanting pilots to get close to two things, the compressibility and at 545 mph IAS, aileron reversal where flexing of the wings caused the ailerons swap directions. In IL-2, all they do is rip off if you use them past that speed. For a more detailed explanation, I feel Greg does a much better job researching and explaining it. This lower dive performance combined with the reduced elevator authority makes doing boom and zoom attacks substantially more difficult. Stall Characteristics: There is a notable lack of buffeting when nearing a stall. This was a positive aspect about the P-47 noted in the British report. I don’t believe this modeled on any aircraft in IL-2. This small detail would aid a lot in aircraft that tend to get into accelerated stalls such as the P-47, P-51, and the various Fokker-Wulfs. In terms of gameplay, the P-47 underperforming is neither fun nor fair. It seems like a pointless option when compared to taking a Tempest Mk.V for dogfighting or P-38J for ground attack. With the recent improvements to .50 cals, an overhaul to the P-47 flight model would make flying in Battle of Bodenplatte more varied and interesting for people flying Allied or Axis. This report lines up pretty much with how the P-47 in DCS handles. It's a much better plane there than in IL2 specially at low speeds. 1 1
BCI-Nazgul Posted October 6, 2021 Posted October 6, 2021 Not exactly sure why you two think is funny or confusing. I've flown the 47 in IL2 a lot and many hours in DCS now. The DCS version is much more forgiving at low speeds than the IL2 version. You get plenty of warning before it stalls out in a turn unlike the IL2 version where you plane suddenly acts like it's wing tip is stuck in concrete. It's also faster with a bomb load on and a lot tougher in DCS. 1 2
354thFG_Panda_ Posted October 6, 2021 Posted October 6, 2021 (edited) Not to turn it into a sim comparison thread but just look at it...(also not my clip, I'm not into those anime things) https://streamable.com/c71axb Edited October 6, 2021 by LR.TheRedPanda
BCI-Nazgul Posted October 6, 2021 Posted October 6, 2021 1 hour ago, LR.TheRedPanda said: Not to turn it into a sim comparison thread but just look at it...(also not my clip, I'm not into those anime things) https://streamable.com/c71axb I haven't pulled any moves like that, but it is much less likely to suddenly stall. Was that an AI 47 or a human piloted one?
DSR_A-24 Posted October 7, 2021 Posted October 7, 2021 6 hours ago, LR.TheRedPanda said: Not to turn it into a sim comparison thread but just look at it...(also not my clip, I'm not into those anime things) https://streamable.com/c71axb I don't know whether that explains why their were so many P-47 aces or why the P-47 maybe impossible to model correctly due to Republic Aviation having deleted their documents. What is very strange is the P-47 behaviours just like this in Aces High. I haven't flown in a while, but when the P-47 came out literally a Spitfire had troubles keeping up with me in a dog fight. Again not to compare sims, BUT IL2 nor DCS is the first to do this. 1
-250H-Ursus_ Posted October 7, 2021 Posted October 7, 2021 On 10/2/2021 at 8:21 AM, Yak_Panther said: I dug through the NASA technical reports about the P-47. Based upon my research the lift coefficient for the P-47 game looks low, the elevator's effectiveness, (ability to generate pitch rate), and the increased loss of elevator effectiveness due to air speed / mach effect is too high. In short, The P-47 it should be more responsive to initial pitch inputs. I will explain each issue in detail below. CL Max The Cl max, in the game, is probably low. It’s currently 1.2 according to the game info. Based on NACA reports the power on Cl max of the P-47 is around 1.4 - 1.5. NACA-ACR-L4127 https://ntrs.nasa.gov/citations/19930092728 I will discuss the lift issue in greater detail, after discussing the handling qualities of the aircraft. The issues related with handling qualities of the aircraft and the mach effects are as Follows: A. The stick forces are too high and the elevator effectiveness is too low. In general the Elevators are not effective enough at generating pitch moments. The aircraft should generate greater amounts of pitch rate per unit of joystick input. The service Cg of the P-47 varies from 27% MAC to over 30%. This helps to reduce the stick forces per G. NACA TN 2899 Provides the stick forces per G for the P-47. At low altitudes, the stick forces per G vary from 7.5 lbs per g at mach .59 to, 5.5 lbs per G at mach .3 https://ntrs.nasa.gov/citations/19930083857 The scale lines are preserved on the older version of this report. NACA L8A06 https://ntrs.nasa.gov/citations/20090022749 Though the stick forces are high for the era. They are not beyond the capabilities of a human. The stick force per G on the P-47, are similar too the stick forces per G onthe F/A-18. Which is ~ 6 lbs per G at high G. https://apps.dtic.mil/sti/pdfs/ADP002709.pdf NACA TN 2899 also shows the Coefficient of Normal forces per degree of elevator angle. And the Normal Force Coefficient generated per degree of Elevator angle. The aircraft is capable of generating large forces with only 4 degrees of elevator angle, Given the elevator is capable of moving to up to 30 degrees trailing edge up. It appears to be effective and well sized. In game the elevator requires almost full deflection to generate pitch rates at speeds near 300 mph at sea level. So the game appears to under-represented how effective the elevators are. Based on these reports, the P-47 should feel more responsive to inputs. Closer to the response of a Typhoon than a bulldozer. Issue B: The loss of elevator control / increase in stick force due to mach effects; These appear to be to high and lead to handling deficiencies throughout the flight envelope. This compounds the general lack of elevator effectiveness, because the mach effects are also applied at too low of an airspeed speed, and altitude. NACA ACR 5D20. Shows the pitch down moment should only occur at Mach greater than .78 https://ntrs.nasa.gov/citations/20150011311 NACA report 5D19, https://ntrs.nasa.gov/citations/20150019985 The uncontrollable nose down moment is not the result of the elevator losing the ability to generate pitch up moments. The primary reason for nose down moment at high mach on the P-47 is the change in lift curve slope resulting in an increase in static stability, coupled with a decrease in lift coefficient required for trim. NACA 3k18 https://ntrs.nasa.gov/citations/19930092521 NACA RM A7F09 A Summary and Analysis of Data on Dive-recovery Flaps https://ntrs.nasa.gov/citations/19930085641 NACA 5D19 https://ntrs.nasa.gov/citations/20150019985 The lack of control above mach .78 is not the result of increased air loads leading to higher hinge moments on the elevator, It’s not a stick force issue. The aircraft should be able to generate high pitch rates even at high airspeeds below Mach .78 NACA 5D20 shows that below mach .78 the elevators are capable of generating pitching moments, without excessive hinge moments. https://ntrs.nasa.gov/citations/20150011311 The nose down tendency from the increased stability due to mach effects, simply over powers the tails ability to trim. At Cl’s greater than .2; The pitch down moment due to the mach effect,at mach .79, are greater than the pitch up moment which can be generated by the elevators. It’s not that the tail becomes unmovable at high mach. Which Is why the primary effect of the dive is to change is to increase the lift coefficient, there by changing the angle of attack need needed to maintain constant lift. From NACA ACR 5D19. https://ntrs.nasa.gov/citations/20150019985 The mach effects seem to be modeled by a decrease in elevator efficiency, eg a loss of pitch rate due to airspeed, ect. When this loss of efficiency is done below mach .78 and coupled with general lack of efficiency of the elevator the result is an aircraft which responds poorly to inputs. The Lift Issue In Detail. The Cl Max of in game P-47 probably too low. It is ~ 1.2, based on the in game technical info Weight 11,385 lbs, stall speed of 111 mph, the wing area is 300 square feet. Flight tests at a gross weight of 12 565 lbs, put the stall speed at 105 mph, power off. http://www.wwiiaircraftperformance.org/p-47/P-47B_41-5902_PHQ-M-19-1417-A.pdf With the instrument correction you applied. The Cl max works out ~1.35 to 1.4 https://reports.aerade.cranfield.ac.uk/handle/1826.2/3148 A power off Cl max of 1.35 to 1.4 agrees with the NACA High Speed Wind Tunnel Tests of the 30% Scale Model of the P-47, NACA ACR 5D30. Which puts the Power Off Cl Max at 1.4 https://ntrs.nasa.gov/api/citations/20150011311/downloads/document-2_Redacted.pdf Various full scale flight tests give a power on Cl max of 1.4 to 1.5. NACA TN 1734 compares The flight test Power on CL max of the aircraft to scale model. It Puts The Cl max of Aircraft at 1.5 Mach .4 It’s further broken out in a chart. https://ntrs.nasa.gov/api/citations/19930082429/downloads/19930082429.pdf The testing was carried out As a part of NACA ACR L4I927. Correlation of Flight Data on Limit Pressure Coefficients and Their Relation to High-Speed Burbling and Critical Tail Loads. https://ntrs.nasa.gov/citations/19930092728 Which also provides sectional lift coefficients. And Calculated V-N diagrams for two different wing loadings 40 lbs per sq feet. ~ 12,000 lbs gross weight. And for a wing loading of 30 pounds per square foot. ~ 9000 lbs gross weight. https://ntrs.nasa.gov/citations/19930092728 The a 1.4 to 1.5 lift coefficient for the aircraft is not surprising. The Republic S-3 airfoil is a derivative of the NACA 23000 series. https://ntrs.nasa.gov/citations/19930093001 The P-47’s wing tapers from a Modified NACA 23015 at the root to a 23009 at the tip. https://ntrs.nasa.gov/api/citations/19930085641/downloads/19930085641.pdf At mid chord the pressure distribution is similar to a NACA 23011 https://ntrs.nasa.gov/citations/19930092751 I’ve plotted the 2-d lift Polar of the NACA 23011 in xfoil at the stall conditions given in the flight test. http://www.wwiiaircraftperformance.org/p-47/P-47B_41-5902_PHQ-M-19-1417-A.pdf It comes out to about 1.8 .Given the way Cl max from a 2d airfoil to an actual aircraft. At 20 % reduction in lift going from a 2d airfoil to an aircraft is reasonable. https://web.mit.edu/drela/Public/web/xfoil/ A power on Cl max of 1.5 is reasonable for this aircraft. Given the size of the wing, weight of the P-47 and the year it was designed; You truly are, the king of kings.
MrRistro Posted October 9, 2021 Author Posted October 9, 2021 On 10/3/2021 at 8:08 PM, Yak_Panther said: Using the aircraft’s indicated airspeed as the sole basis for determining the maximum lift coefficient is problematic. So is trying to derive it, based on the slope of the correction, because the instrument corrections can also become nonlinear at low airspeeds. Due to instrument mechanics and probe position. Below is the instrument correction for the F6F Hellcat. As derived from flight testing, a trailing instrument probe was used to compute the corrections. To derive the maximum lift coefficient we should use a variety of sources . Ideally would be a full scale wind tunnel test with aircraft in service condition. Next best, would be flight tests whose purpose was to determine the maximum lift coefficient. Optimally these tests should also be conducted with an instrument package more accurate than the aircraft’s. This type of data is available. An inflight test of the P-47, with an instrument package, to determine the maximum lift coefficient of the aircraft at various Mach was conducted and is available. NACA L4I27 https://ntrs.nasa.gov/citations/19930092728 One of the purpose of this test was to determine effect of Mach on the maximum lift coefficient of the P-47 I cited this Report in my first post. The authors took the time to apply the appropriate corrections in their calculations of the lift coefficient. .The Cl max from these flight test at 15,000 feet mach .27 was 1.8 A second sets were conducted to measure the pressure distribution over the wing. A second set of Cl max’s were derived from pressure measurements taken over the wing. The two test were compared. In a second chart. The Cl max was around 1.7 at Mach .3 Let’s not be satisfied with one test, and see if there is more data which will tell us about the Cl max of the aircraft. There are wind tunnel test of the scale model of P-47. These test show a Cl max of 1.4 at an angle of attack at 15 mach .2 Let’s look at some other test of the era and see if they can give us any insight into what the Cl max should be. NACA report 792, measured tail load of the aircraft at Cl Max / Max G The airplane weighed 11,900 lbs ti 12,000 lbs, The test were conducted at 6000 feet. The stall was 4.5 G at 212 mph. Which yields a Cl max of 1.58 to 1.49 https://ntrs.nasa.gov/api/citations/19930091869/downloads/19930091869.pdf Then We have “Analysis of the Aerodynamic Design of the P-47B Airplane.” Which describes the aerodynamic evolution of the aircraft and the wind tunnel testing carried out at Langley. This report cites the Cl Max of P-47 model was 1.63 https://ntrs.nasa.gov/api/citations/20150014120/downloads/20150014120_Redacted.pdf All this data plus stall test, seems to put the Cl max of the aircraft in power off at around 1.4 and the power on Cl 1.5 to 1.6. Let’s expand our sanity check to other aircraft with similar wing profiles. The F6F uses similar airfoils. A modified 23015 tapering to a 23009. https://reports.aerade.cranfield.ac.uk/handle/1826.2/3510 Based airspeed from the trailing probe, the Cl max of the Hellcat is power off is 1.64 The results of the previous NACA testing of the P-47 are within reason for what is achievable with this wing form. The P-47 numbers are slightly higher though. Is there anything special about this aircraft that could yield the slightly higher Cl max? Yes there is; “Analysis of the Aerodynamic Design of the P-47B Airplane.” shows us the designers spent the time to minimize the airflow interference between the fuselage and the wing roots. One of design features unique for the P-47 is the fuselage taper. The fuselage does not taper until behind the trailing edge of the wing. This would increase the lift and lower drag, despite the increase to wetted area. When we look at all the data combine, it becomes clear that Clmax for this aircraft is from 1.4 to 1.6. God damn you are exceptional. At this point 1C should give you a job.
Denum Posted October 12, 2021 Posted October 12, 2021 Just dropping in to say that I thoroughly enjoy Yaks posts So much data I have to make a coffee and sit down for 30 minutes to fully appreciate it. 1
LColony_Kong Posted October 12, 2021 Posted October 12, 2021 On 10/7/2021 at 12:11 AM, DSR_A-24 said: I don't know whether that explains why their were so many P-47 aces or why the P-47 maybe impossible to model correctly due to Republic Aviation having deleted their documents. What is very strange is the P-47 behaviours just like this in Aces High. I haven't flown in a while, but when the P-47 came out literally a Spitfire had troubles keeping up with me in a dog fight. Again not to compare sims, BUT IL2 nor DCS is the first to do this. It also does this kind of thing in DCS, but is somewhat more tame about it. I am not saying any specific aspect of any of the P-47s flaps out slow speed behaviors is correct, but there might be something to this behavior since it has now come up in 3 different flight sims separated by decades using completely different modeling methods.
ZachariasX Posted October 12, 2021 Posted October 12, 2021 40 minutes ago, LColony_Red_Comet said: I am not saying any specific aspect of any of the P-47s flaps out slow speed behaviors is correct, but there might be something to this behavior since it has now come up in 3 different flight sims separated by decades using completely different modeling methods. Lifting line theory is good at geting performance figures right, it tells you next to nothing what happens (and how things happen) at the very edge of the enveloppe, where we venture most of the time. The sims based on similar FM logic are prone to producing similar artefacts. It is very hard having control response over the entire speed range right, especially when you don't have access to the real aircraft or have sketchy data. Control response vs. plane weight (inertia) is a particularly tough nut to crack. You can give it a lot of control, and you get a butterfly of a plane like in the ridiculous videos posted above. You can give the controls less bite, but then you get the wobbly, rubberbanding slug that pleages most FM's in some way. They may dampen the oscillations, but then they dampen inputs as well. I have yet to see a real aircraft certified for aerobatics that is lagging stick inputs as the simulated planes in almost all sims do. You find that aircraftin sims are generally lagging control input. This to varying degrees. This makes precise flying hard. It's like putting a Chevy steering in a Porsche. ("Well, it has the same turn radius, so what's your problem?" Regarding this sim, I see nothing specific to the P-47 that is not how it (reasonably) could be. What the FM may be suffering from, that I find on many aircraft, the Spit XIV being the biggest victim. (I hope she gets an FM revision at some point because that wale is not a Spit yet.) As almost no simulation gets these things really right, I don't expect a simple fix. For any plane.
sevenless Posted October 12, 2021 Posted October 12, 2021 Unrelated to the topic at hand, nevertheless worth watching: Ramrod to Emden, October 2nd 1943. The P-47Ds appearing in the film belong to the 334th, 335th, and 336th Fighter Squadrons of the 4th Fighter Group Flying Eagles and the 61st, 62nd, and 63rd Fighter Squadrons of the 56th Fighter Group Zemke’s Wolfpack. The P-38Hs were assigned to the 38th, 338th, and 343rd Fighter Squadrons of the 55th Fighter Group Fightin’ 55th.
Cpt_Siddy Posted October 12, 2021 Posted October 12, 2021 (edited) 3 hours ago, ZachariasX said: Lifting line theory is good at geting performance figures right, it tells you next to nothing what happens (and how things happen) at the very edge of the enveloppe, where we venture most of the time. The sims based on similar FM logic are prone to producing similar artefacts. It is very hard having control response over the entire speed range right, especially when you don't have access to the real aircraft or have sketchy data. In the age of computer simulations, i find it odd that there is no computational fluid dynamic simulations ordered to solve these issues computationally. Considering we already have answers of what sort of female pilots preform best in open style cockpit... https://www.researchgate.net/publication/322530755_Analysis_and_Qualitative_Effects_of_Large_Breasts_on_Aerodynamic_Performance_and_Wake_of_a_Miss_Kobayashi's_Dragon_Maid_Character or how mineshot preforms on p-47's skin Edited October 12, 2021 by Cpt_Siddy
ZachariasX Posted October 12, 2021 Posted October 12, 2021 23 minutes ago, Cpt_Siddy said: In the age of computer simulations, i find it odd that there is no computational fluid dynamic simulations ordered to solve these issues computationally. If it has to be done for every plane in the sim and still produce 100 FPS while computing thousands of bullets zipping through the air and entire aircraft systems, then it starts to get difficult. Plus you have to have programmers that can do all of that. 2
unreasonable Posted October 12, 2021 Posted October 12, 2021 Computational simulations are just hypothesis generators - I would like to see the empirical test results that validate the projections, no matter how impressive, particularly for the Dragon Maid. 1 1
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