LLv34_Flanker Posted May 8, 2014 Posted May 8, 2014 S! Got a couple of pages concerning the Bf109G-2 turning performance and also acceleration/deceleration data. Tests were performed with a Bf109G-2 rated at 1.31ata/2600rpm. Translation underway
LLv34_Flanker Posted May 8, 2014 Author Posted May 8, 2014 (edited) S! First snippet incoming. The plane was flown with full fuel, guns loaded with ammo, Malmi airfield/Helsinki) in march 1943. Pilot: Captain Pekka Kokko. No external stores attached. Keep in mind I will try to get more data and add it here, as of now a bit incomplete. Horizontal turns The turning capabilities of the plane are good compared to other planes with a high wing loading that pilot can not pull the plane into a too tight turn until speed is below 350km/h and with engine on less than full power. In this situation the plane can be "stalled through" which results in opening of the leading edge slats and elevator becoming lighter. If the turn is tightened and as speed reduces the turn stops and plane begins to shudder ; continuing the pull the plane stalls to left wing and nose drops. If decreasing the pull turn can be continued. Turn results achieved at 1000m altitude. Type of turn Time Start speed End speed Bank angle Fast 180deg. turn 10" 450km/h 380km/h 90deg Fast 360deg. turn 18" 450km/h 330km/h 90deg Cont. 360deg. turn, max power 22" 360km/h 360km/h 70deg Acceleration and deceleration in horizontal flight Acceleration of the plane is good; deceleration is relatively slow especially in slower speed regime. Start speed End speed Time Power setting 300km/h 440km/h 27" Maximum 440km/h 510km/h 35" Maximum 510km/h 440km/h 9" Idle 440km/h 300km/h 33" Idle Radiator flaps can be used for deceleration. Edited May 8, 2014 by LLv34_Flanker 5
Kurfurst Posted May 8, 2014 Posted May 8, 2014 (edited) Performance trials and background of the same plane available at : http://kurfurst.org/Performance_tests/109G_MT215/109G2_MT215_en.html Do you have the full trials, Flanker? Soviet trials with captured G-2 that was measured some 30 km/h faster resulted in a sustained turn time of 20 secs at 1000 m. Edited May 8, 2014 by VO101Kurfurst 3
bivalov Posted May 8, 2014 Posted May 8, 2014 although i seen some information before, about 22 seconds, for example, it's interesting and will be interesting anyway...
Crump Posted May 12, 2014 Posted May 12, 2014 Cont. 360deg. turn, max power 22" 360km/h 360km/h 70deg That is fantastic stuff, Flanker. It gives good agreement with the calculations I did for Kurfurst. 360kph IAS ~ 194KEAS = 194KEAS * 1.0498 SMOE at 3280 feet (1000 meters) = 203KTAS Turn rate on the chart at 203Knots = 16.74 degree/sec = 21.5 seconds complete a 360 degree constant altitude steady state turn with a ,maximum sustainable bank angle of 72 degrees. 2.2% error on a quick SWAG is not bad, lol. What instruments did they use to record the performance? 3
LLv34_Flanker Posted May 13, 2014 Author Posted May 13, 2014 S! They used the Mata Hari test equipment added with instrumentation from Vaisala. Quote about Mata Hari: "The first modern flight recorder, called "Mata Hari", was created in 1942 by Finnish aviation engineer Veijo Hietala. This black high-tech mechanical box was able to record all important aviation details during test flights of World War II fighters that the Finnish army repaired or built in their main aviation factory in Tampere, Finland. The "Mata Hari" black box is displayed in the Vapriikki museum in Tampere, Finland."
FTC_Cule Posted May 13, 2014 Posted May 13, 2014 Really good stuff. I guess the F4 will have tighter turns due to its lightweightness? 1
LLv34_Flanker Posted May 13, 2014 Author Posted May 13, 2014 (edited) S! It could be a thread of it's own. Data measured from game pitted against historical data. So far the acceleration and deceleration values of planes we have data of, Bf109G-2 and LaGG-3 Series 35, are off the mark by a margin. Series 35 was not that much of an improvement over Series 29 that the data would differ any or if so, insignificantly. This is what we are investigating now. Edited May 13, 2014 by LLv34_Flanker
koko Posted May 13, 2014 Posted May 13, 2014 (edited) What instruments did they use to record the performance? couple pics about the mata hari Edited May 13, 2014 by koko 1
sturmkraehe Posted May 13, 2014 Posted May 13, 2014 Do we know about altitude lose during one circle? Crucial information imho!
Crump Posted May 14, 2014 Posted May 14, 2014 Many nations used similar devices. Here is an example from a Focke Wulf test flight: Does the report include a Position Error Correction chart?
LLv34_Flanker Posted May 14, 2014 Author Posted May 14, 2014 S! AFAIK the Bf109G-2 did not lose altitude in continuous turn. It was a measured continuous turn keeping 70deg bank angle and about 3G pull. Crump, need to check the LaGG-3 test sheet for this, give me a bit
Crump Posted May 14, 2014 Posted May 14, 2014 No problem, Flanker! I hope they have a PEC curve for the Bf-109G2......
sturmkraehe Posted May 14, 2014 Posted May 14, 2014 Oh I am however quite certain that they lost altitude with a bank angle of 90° while 70° is a lot (only cos 70° = 34% of lift in the vertical)
Crump Posted May 14, 2014 Posted May 14, 2014 (edited) Oh I am however quite certain that they lost altitude with a bank angle of 90° while 70° is a lot (only cos 70° = 34% of lift in the vertical) At 90 degrees of bank the load factor becomes infinite. That does not mean the turn is impossible, it just means the wings are not loaded as our model of a steady state constant altitude turn. That steady state model is no longer applicable is all. The entire lift vector is now oriented towards the center (providing centripetal force to maintain turn). The elevator is still used to load the wings but essentially the airplane thinks it is in a climb as the lift vector is no longer split between offsetting weight and providing centripetal force. It is pure instantaneous performance. The fuselage side force as well as lift from the vertical stabilizer/rudder will provide a significant amount of force to offset weight. Additionally a normally present vector of thrust that shift in a turn to offset weight will become much more significant. A steady state turn maintaining speed and altitude is an impossibility but in this case, it is not steady state. The choices are maintain speed and lose altitude or lose speed to maintain altitude. In this case altitude is traded for airspeed losing some 70 kph in the 180 degree turn and 120 kph in the 360 degree turn. A good example of an airplane designed to take advantage of the sideforce/thrust vector is the G-Bee racer. It was designed with knife edge pylon turns used in racing in mind. In addition, it turned out that the fuselage acted as an airfoil, like the 'lifting-body' designs of the 1960s. This allowed the aircraft to make tight "knife-edge" turns without losing altitude. It was, in effect, a Pratt & Whitney R-1340 engine with wings and a tail on it. http://modelingmadness.com/review/civil/tmcr1.htm Now, the Bf-109 is not a lifting body design so don't think anyone is claiming that. The 180 degree turn I doubt they lost any altitude but the 360 degree turn is questionable, not impossible but questionable. I would like to see the reports details as well. Edited May 14, 2014 by Crump
koko Posted May 15, 2014 Posted May 15, 2014 Start speed End speed Time Power setting 300km/h 440km/h 27" Maximum 440km/h 510km/h 35" Maximum 510km/h 440km/h 9" Idle 440km/h 300km/h 33" Idle Bf109G-2 Acc/Dec in game: Start speed End speed Time Power setting 300km/h 440km/h 17,6 sec Maximum 440km/h 510km/h 18,0 sec Maximum 510km/h 440km/h 10,3 sec Idle 440km/h 300km/h 28,7 sec Idle All tested 3 times with max fuel. Altitude about 50m autopilot on. Started from stable speed 300km/h (45%) or 510km/h (90%) only hmmm <S>koko 1
LLv34_Flanker Posted May 15, 2014 Author Posted May 15, 2014 (edited) S! As -koko- posted above the acceleration of the Bf109G-2 is off the chart by a considerable margin, 10sec at the first speed increase and 17sec on the second. This makes total error of 27 seconds. Deceleration is much closer to tested results. First drop within 1sec and the second within 5sec, so within 6 seconds. These same tests will be conducted on the LaGG-3 in game and pitted against Series 35 test flight results. Enjoy. Edited May 15, 2014 by LLv34_Flanker
Crump Posted May 15, 2014 Posted May 15, 2014 S! As -koko- posted above the acceleration of the Bf109G-2 is off the chart by a considerable margin, 10sec at the first speed increase and 17sec on the second. This makes total error of 27 seconds. Deceleration is much closer to tested results. First drop within 1sec and the second within 5sec, so within 6 seconds. These same tests will be conducted on the LaGG-3 in game and pitted against Series 35 test flight results. Enjoy. It is a high density atmosphere. The deceleration is more off than the acceleration if it is flown during a Russian winter!! It should accelerate faster and decelerate faster compared to a standard environment.
LLv34_Flanker Posted May 15, 2014 Author Posted May 15, 2014 S! But now it accelerates nearly 30 seconds FASTER than normally. Deceleration is within 6 seconds of tested values. So it would be nice to have a "standard atmosphere" to test in.
AX2 Posted May 15, 2014 Posted May 15, 2014 Developer Diary 51 From now on our internal combustion engine model takes into consideration the state of atmosphere. For example: its winter outdoors, the air is cold which allows an engine to perform with more power. The system is universal and homogeneous so it can be implemented in other theatres of war if we choose to make those. So, keep in mind that you should know the weather forecast before going on a mission. Here in Stalingrad it is -15C, so the engines have their power increased some. Should it influence your perception of well-known planes? Well, you'll see it soon. But the difference is huge.
Crump Posted May 15, 2014 Posted May 15, 2014 S! But now it accelerates nearly 30 seconds FASTER than normally. Deceleration is within 6 seconds of tested values. So it would be nice to have a "standard atmosphere" to test in. Performance of propeller aircraft goes up dramatically in the wintertime! IMHO, it should decelerate much faster than koko's test. 510km/h 440km/h 10,3 sec Idle It took 9 seconds in the actual test UNDER test conditions which we don't know because it has not been posted. So, is the data converted to CINA or under what conditions was it recorded? If it is summertime or CINA, then the airplane should decelerate faster than 9 seconds!! Understand too, this is a computer model and will not mirror reality in all things. Not unless we all want to spend ALOT more money on hardware!! We have to accept some margin of error and be reasonable. If the relative performance trends are correct, then the model is valid. Make sense?
JtD Posted May 15, 2014 Posted May 15, 2014 It would be really important to know the Finnish testing procedures in this case. It could explain the entire difference. If you look at their times, the gain in kinetic energy from 300 to 440 equals a height gain of about 400m. Climbed in 27 seconds, you're at ~ 15 m/s. This is pretty low, in particular looking at the ~20m/s climb rate they tested for the 109. So no one should draw the conclusion that the game is fundamentally wrong for as long as the Finnish testing data cannot be interpreted properly.
Crump Posted May 15, 2014 Posted May 15, 2014 (edited) But the difference is huge. It is a huge difference in reality. Look at the density altitude chart. An airplane at 40C at a pressure altitude of 5000 feet thinks it is operating at 8500 feet due to the air being less dense in the summertime. The same airplane at -20 degrees in the wintertime at a pressure altitude of 5000 feet thinks it is operating at on 1800 feet!! 8500 - 1800 = 6700 foot altitude difference due to density altitude effects. That is huge! The thrust increase in the wintertime gives most aircraft 100% to 200% change in climb rate comparing summer to winter performance! Edited May 15, 2014 by Crump 2
Crump Posted May 15, 2014 Posted May 15, 2014 JtD is right. Without knowing the atmospheric conditions the performance is measured for both data sets.....there is no real conclusion that can be drawn for specific data. The trend should be the higher the atmospheric density, the faster the aircraft accelerates and the faster it decelerates.
Matt Posted May 15, 2014 Posted May 15, 2014 (edited) In addition to that, it looks like the plane tested also saw almost one full month (it flew on 10th March to Finnland and was tested on 10th April) use before running these tests. Comparing it with the performance of a completely new plane (which we always have in BoS according to the devs) might be a bit risky. It also had a non-retractable tail wheel. Edited May 15, 2014 by Matt
Crump Posted May 16, 2014 Posted May 16, 2014 In addition to that, it looks like the plane tested also saw almost one full month (it flew on 10th March to Finnland and was tested on 10th April) use before running these tests. Comparing it with the performance of a completely new plane (which we always have in BoS according to the devs) might be a bit risky. It also had a non-retractable tail wheel. Good point, Matt Crump nice data. Thank you!
LLv34_Flanker Posted May 16, 2014 Author Posted May 16, 2014 S! The plane was brand new when received, Erla factories built it. It had flown very little at the time of tests, because all planes were taken to Lentokonetehdas (State aircraft factory) for painting etc. before put to service. So the difference to a new or very slightly used is next to nothing if any. I would not stick to that, as the figures attained were within factory specs. The test part can be found on Kurfürst's page with info on weather and temperature information. I provided him with the actual flight testing reports as well, in which the plane was tested in different maneuvers and such. But his page has the charts for the results on the MT-215. Seems I have to sit down with -koko- and prepare a nice package here with data. There are others too working on these reports on Bf109G and LaGG-3
Crump Posted May 16, 2014 Posted May 16, 2014 The results are noted to be corrected to CINA and for compressibility effects, various intrument errors. Test flights were performed in order to eliminate windage errors (these are not reproduced here). http://kurfurst.org/Performance_tests/109G_MT215/109G2_MT215_en.html In the low density altitude of wintertime, the aircraft accelerates faster and it decelerates faster than standard. the figures attained were within factory specs That is what is important.
Holtzauge Posted May 17, 2014 Posted May 17, 2014 It looks like the performance figures are a bit off. As some of you in this forum knows, I have a computer simulation of a number of aircraft that can give an indication of speed, acceleration, climb and turn rates etc and if I run the F4 (don't have the G2 modelled) at 1000 m alt, 1.3 ata boost, 15 deg C temp, 2900 kg weight I get the following results: Best turn=19.7 s turn time @ Vt=274 Km/h Turn time at a maintained speed of Vt=360 Km/h = 22.6 s Acceleration time Vt =300 to 440 Km/h = 27,0 s Acceleration time Vt =440 to 510 Km/h = 31.7 s So while this if for the F4 not G2, the figures indicate significantly longer acceleration times than what you seem to see in the sim right now.
LLv34_Flanker Posted May 17, 2014 Author Posted May 17, 2014 S! Nice post Holtzauge. The values in game seem to be a bit off. I do not think that the cold weather would give a boost of ~30sec in acceleration. That is a significant amount. Finnish testing methods were and are fully comparable with other nations' results. Vaisala did provide excellent instrumentation and other applications and continues to do so even today. Mata Hari recording device was one of the most advanced devices of it's time with the capability of recording 8 different inputs from the flight. Anyways, let's stay on topic
Holtzauge Posted May 17, 2014 Posted May 17, 2014 Yes, the difference seems to large by far. I guess you could extrapolate from some other test to get an idea of the delta between different temperatures. Don't have have time to dig into this myself but one idea would be to find another test (even on another aircraft type) and see how large corrections were applied there and extrapolate that on the Finnish tests to get a ballpark figure on how large the effect would be. My guess is than it would be way lower than the what you see ingame now since while the engine does deliver more hp, the air gets denser so those factors would work against each other.
Crump Posted May 17, 2014 Posted May 17, 2014 I guess you could extrapolate from some other test to get an idea of the delta between different temperatures. That is not going to work very well. It is not hard to calculate performance under other atmospheric conditions. If there is an altimeter setting in game look at it and let us know the number in the Kollsmann window. Most airplanes have an Outside Temperature Gauge which can read the temperature. Once you know the altimeter setting and temperature, set the aircraft's kollsmann window setting to 29.92inHG or 1013mb and climb to 1000meters pressure altitude. Conduct the test in the game and record the data. Then you can convert that data to standard conditions very easily. You must know the pressure, temperature, and aircraft performance at pressure altitude. You will find the difference is dramatic.
Crump Posted May 17, 2014 Posted May 17, 2014 Wurkeri says: So while this if for the F4 not G2, the figures indicate significantly longer acceleration times than what you seem to see in the sim right now. Based on calculations at: It looks like the performance figures are a bit off. As some of you in this forum knows, I have a computer simulation of a number of aircraft that can give an indication of speed, acceleration, climb and turn rates etc and if I run the F4 (don't have the G2 modelled) at 1000 m alt, 1.3 ata boost, 15 deg C temp, 2900 kg weight I get the following results: Standard conditions......and no atmospheric data from the game performance????? Not to mention there is an acceleration difference between the Bf-109F4 and Bf-109G2. Your Bf-109F4 data agrees with the Finn's Bf-109G2 data There just is not enough information to draw any specific conclusion outside the trend it should accelerate faster and decelerate faster under low density altitude conditions. Koko's game data shows the general trend: The aircraft accelerates better under low density altitude conditions which is correct. The aircraft decelerates the same or slightly better under low density altitude conditions which is not correct.
Holtzauge Posted May 19, 2014 Posted May 19, 2014 Just thought of a way to do a sanity check: Instead of digging up engine performance data, reverse engineer power needed to get the above quoted in game accelerations in a -15 deg C atmosphere: So targeting an acceleration time of 18 s at -15 deg C instead of the standard 27 s at +15 deg C to accelerate between 300 and 440 Km/h what would it take in terms of a power increase in the Me109 F4? Turns out it requires that the engine delivers 30% more power when lowering the temp to -15 deg C. Is that reasonable? I think not: This amount of power boost would increase the top speed at 1 km from around 551 Km/h to 583 Km/h and the climb rate from around 17.8 m/s to a whopping 24.4 m/s. If the F4 ever attained that IRL I suspect we would have heard about it. True, this is for the F4 and not the G2 and I'm sure someone will pounce on that fact but since this is an exercise in deduction based on logical reasoning I suspect this is a lost cause anyway in some departments. Speaking of that Crump: I notice you quote me as Wurkeri above but that not me. Whatever lead you to that conclusion? OTOH since Wurkeri is another guy who usually disagrees with you perhaps that's where the confusion stems from?
Crump Posted May 20, 2014 Posted May 20, 2014 Just thought of a way to do a sanity check: Instead of digging up engine performance data, reverse engineer power needed to get the above quoted in game accelerations in a -15 deg C atmosphere: So targeting an acceleration time of 18 s at -15 deg C instead of the standard 27 s at +15 deg C to accelerate between 300 and 440 Km/h what would it take in terms of a power increase in the Me109 F4? Turns out it requires that the engine delivers 30% more power when lowering the temp to -15 deg C. Is that reasonable? I think not: This amount of power boost would increase the top speed at 1 km from around 551 Km/h to 583 Km/h and the climb rate from around 17.8 m/s to a whopping 24.4 m/s. If the F4 ever attained that IRL I suspect we would have heard about it. True, this is for the F4 and not the G2 and I'm sure someone will pounce on that fact but since this is an exercise in deduction based on logical reasoning I suspect this is a lost cause anyway in some departments. Speaking of that Crump: I notice you quote me as Wurkeri above but that not me. Whatever lead you to that conclusion? OTOH since Wurkeri is another guy who usually disagrees with you perhaps that's where the confusion stems from? There is nothing to conclude without knowing the atmospheric conditions. And yes, they can vary performance considerably.
sturmkraehe Posted May 21, 2014 Posted May 21, 2014 I have a few questions and concerns. But first of all: We realize that the 109G is performing ingame significantly (!) better than what the Finnish tests showed. The devs said a certain performance increase due to cold weather is implemented. My question is: The increase compared to what? For instance: What were the conditions under which the Finnish tests were done? If it was done in winter at temperatures comparable to what we have in represented in BoS then something is completely wrong. If the temperature during the Finnish tests was in the middle of summer with something like 20°C we can expect that Finnish tests may result in less good numbers than what we have in game. The question by how much the performance improves per °C temperature? And here is a big concern: Unless we do not have reliable data on the atmosphere used during RL tests and unless we don't get standard atmosphere in BoS as an option for missions all these comparing stuff is pretty but does not help to assess the ingame representation of a realistic performance. The only thing we can do is to see if all planes benefit about the same relative performance increase - supposing the RL tests are all at standard atmosphere.
JtD Posted May 22, 2014 Posted May 22, 2014 All other conditions the same, 30°C less temperature might give you around ~10% extra power and ~15% extra thrust at the same indicated airspeed. With the figures given, only about half the engine power went into climbing. The other half went into drag (and other losses, like propeller). Nearly all the extra power will go into extra climb rate. This means that a 30° temperature drop can increase climb rate here by 20, 25%. If you compare a test of 25°C summer with -30°C winter, it could be even more. As important as they are, I wouldn't get too focussed on the atmospheric conditions. From what we've seen so far, we don't know plane weights, we don't know if speeds are indicated or corrected to whatever, we don't know if they were accelerating through the speed range or started the timing upon advancing throttle, ... - too many things still unknown. I suppose all this can be clarified.
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