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Dave

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Everything posted by Dave

  1. I don't have visibility of 1CGS' FM source, but I will make a comment with regard to the construction of such models in general and leave it to AnPetrovic to correct me regarding his exact design.In physically-modelled simulations documents and records of output parameters such as roll rate are not used at all as input to the FM. The purpose such documents serve when you have built an aerodynamic model based on calculations of flow around a 3D structure is to aid in confirmation of the validity of your model. That is to say, there is not some table where you have "roll_rate=X" which you copied from some report. That would be an output of the calculation not an input. One way you generate that output would be to consider the entire aircraft surface as being made up of tiny patches or elements (finite element analysis) upon each of which you mathematically calculate the resultant forces of airflow many times for each combination of input parameters for the element (such as air density, flow velocity, angle of incidence ...) and then integrate those results over the entire surface. If the elements are small enough the result will be "close enough" to reality. You then stuff the results into multidimensional arrays (indexed on the input variables) so your computer doesn't have to perform the calculations at runtime. The values in the array are discrete so you use interpolation to generate approximations of the continuous values. The accuracy of the output depends, among many factors, on the number of input axes, the resolution of samples, the accuracy of the 3D model and the quality of the fluid mechanical model. This may not be how BoX is done, but I suspect something at least similar to this approach. The point I am trying to convey is that attempting to control or "tweak" the models accuracy using the output is at worst futile and at best a very time consuming process of trial and error. What they seem to be doing instead is trying to get the input parameters as accurately modelled as possible and they compare measured results with whatever historical documentation is available to see how close they are. Given the difficulty inherent in this process conflicting values within some tolerance must be taken with a bucket of salt. So people shouldn't make a major case out of say a 1 degree per second roll rate discrepancy with some test report especially as the measurement accuracy of such reports possibly contain larger errors than the team's software model in some cases. Edit: accidental double post
  2. Maybe read the other threads on P40 engine limits rather than risk that topic being reborn here.
  3. Man I am certain you know that isn't what I was saying or even why I mentioned that example. The point of that example was that it was one that could be found in this forum that proved the P40E was used to war's end in the Pacific by at least the RAAF and they weren't all "late model" P40s in the PTO as Farky seemed to believe. For the record - if you check every P40 thread here you will see that I have always suggested a realistic indicative "limit" of 60" for 20 minutes - despite evidence presented of widespread setting of WEP to 66"Hg in WDAF units in the North African desert in 1942.
  4. I question the validity of that entire argument (Han's) because the date at which people's expectations (and therefore documentation) were revised doesn't have to coincide with the engine's capabilities. What I'm trying to say is that the specific V1710 engine used in the P40E didn't suddenly improve - what changed was the operators' understanding of its capabilities which to that point had been greatly underestimated.
  5. We (RAAF) operated the P40E in the PTO - specifically Guadalcanal and New Guinea. The after action report that I provided in another thread which documented a P40E evading a Zero on the deck at ~70" of manifold pressure for about 15 minutes (pulling these numbers from memory) was written up by a P40E pilot.
  6. This isn't flight test data, and you could argue it is not objective, but Bobby Gibbes was a straight talking realist who had the benefit of flying many types including the 109 F-4 and 109 G-2 who had the utmost respect for both the aircraft and their pilots. It is anecdotally interesting ...
  7. Sigh. Trimming was easy at beginning and early stage of the dive because airspeed hadn't yet produced control forces sufficient to impede said trim adjustment. This doesn't imply that trimming down is any more or less difficult than trimming up. I can't believe this is what you understood it to mean. BTW I supplied not one, but two, sources supporting this. And if you search this forum for "109 trim" you will find that I and others have collectively supplied several other historical reports and records of interview which all corroborate this assertion. Mr Physics and Mr Reality also concur that as airspeed increases the force required to deflect a surface into the airstream increases. So, in short, I base it on several period reports and my sound understanding of the mechanics of flight (BSc (Physics) + postgrad study in aeronautical engineering + a few hundred hours of stick and rudder time). No hours in these ... but plenty of hours in these ...
  8. I don't know. But it shouldn't be too difficult to calculate by modelling the airflow and resultant forces on control surfaces ... oh wait - thats what they are doing. I'm going to reserve further judgement until the changes discussed in the DD are released.
  9. It doesn't. When did I say that?
  10. There is no way the change would be in response to this thread - the issue they refer to in the DD was identified last year. Besides, changes to a software product follow a process which, beyond show-stopping bugs, takes longer to effect this degree of change than the two weeks this thread has existed. It also isn't a "consequence of introducing one big change that required a ton of other micro changes to balance it out" if the developers' own statements are to be believed. It seems the fluid-dynamic modelling they had used previously to build their FM didn't correctly account for some flow interactions caused by airflow around the empennage. Perhaps they had only modelled the lifting and control surfaces independently - I don't know. Based on the explanation given in the DD it would seem also that the aerodynamic force changes due to increasing airspeed had been incorrectly computed or neglected. Specifically trim operation in 3 aircraft which I mentioned to have implausibly high rates of change at high speed is affected - the P40, Mig3 and Bf109. It read to me as though the engineering team: - had previously applied per-aircraft "tweaks" to what was otherwise a globally physically-modelled system because at the time they simply couldn't account for the observed errors in behaviour; - have finally discovered the root cause of the problem in a rather unexpected part of their modelling process; - have resolved to correct the global root cause which will require recalculation of flight model parameters for every aircraft (I assume they perform offline precalculation for multidimensional arrays which are used in game as current comsumer hardware just doesn't have the grunt to do this in real time); and - plan to update each aircraft as their recalculated FM parameters are complete. So I don't think there is any "balancing out" going on here - just a much needed fix to a weakness in the core assumptions of their FM generation. NB: I may have read between the lines a bit due to being employed as a software engineer in the development of physical system modelling for fluid mechanical systems.
  11. Very busy with work today but here are two: The report on the captured G-2 "Black 6" mentions that the stabiliser trim wheel becomes almost solid at high speed, indicating that a more accurate model for trim actuation would consider a rate inversely proportional to airspeed with a some limit (which we can argue over) beyond which it become practically inoperable (and certainly not easily operable as it is now). I believe this is the reason SOPs instructed pilots to trim for dive recovery before entering such dives and use forward stick pressure to maintain a nose down attitude. " 13. The Elevators harden up at high speeds and retrimming is necessary, which is difficult as the twin wheel hardens up and becomes almost solid in a dive." http://www.wwiiaircraftperformance.org/me109/me-109g2-trop.html A report on the G-6 also discusses the difficulty in adjusting pitch trim at such speeds (it is my understanding that the 350 IAS is expressed in miles per hour so as to avoid confusion of allied pilots - this equates to about 564km/h but even the 350 would be a rounded and slightly imprecise figure) ... "11. The rudder is fairly heavy but not uncomfortably so. As there is no rudder trimming device, it is necessary to apply right rudder for take-off and left rudder at high speeds. The ailerons become increasingly stiff with the increase in speed especially at speeds in excess of 350 I.A.S. At speed below 180 I.A.S. the ailerons are not positive and as the stall is approached they are almost non-effective. The elevators also become increasingly difficult to operate as the speed increases. Above 350 I.A.S. this unpleasantness is accentuated as the elevator trim is practically impossible to operate." http://www.wwiiaircraftperformance.org/me109/me109g6-tactical.html
  12. As I have already said I intend to do exactly this to the extent possible within the restrictions of the game, and I had no intention of commenting further until I had done so, but some individuals feel compelled to ridicule any perfectly reasonable question around FM fidelity when it requests a re-evaluation of the in-game capability of their favourite aircraft. When ridicule devolves into assertions of ignorance and stupidity I feel compelled to respond.
  13. No I did not. It's possible to dive away at max speed at 5 degrees declination. You can also dive away at full throttle at 90 degrees if you like. I have not said anything to contradict this. You've posted my exact words and yet you still fail to comprehend their meaning. Rather than cherry pick the bits you want to attack out of context please try to be mature about it and consider my entire statements.
  14. This is what you said sarcastically in dispute of my assertion that attempting to recover from a fast (near airframe limit) dive close to the ground would likely result in a CFIT. I responded with the factual tactic advocated for use in that circumstance. You now supply a very different scenario where your comment seems appropriate, absent the original context, to steer the debate well away from your earlier tripe. "Mission parameters did not permit blah blah ..." It seems that you are now talking about bomber escorts not leaving their bomber formation to chase the interceptors as they dove away. While true, this has nothing to do with the topic of low recovery from a steep dive at Vmax or the validity of my statement that operation of the stabiliser trim in said circumstances was practically futile. I have never proposed that 109s can't dive away at high speed, nor disputed that would-be pursuers may have a multitude of reasons for not giving chase. I presented a very constrained scenario - you ridiculed that statement with a claim that was factually inaccurate if we are to assume that you were attempting to directly refute my own position - I corrected you. No need to "read up on" it thanks. Already did that during my military education.
  15. You are seeing what you want to see rather than what is written. The Colonel did not mention at what point trimming out was necessary and you have assumed that it was at the bottom of a dive after maximum airspeed had already been reached. I will post the RAE reports again as soon as I have some spare time - I am currently at work.
  16. Hmmm lets see ... you made the arrogant statement twice that allied reports carried no weight as though allied crews were incapable of accounting for the condition of the aircraft. I admit that when I just went back and checked - an earlier statement that I had attributed to you regarding performance claims being invalid because ... German engineering ... was actually made by someone else. I have referenced supporting documents - you simply choose to disregard the reports which we (ie English word in this context referring to those assembled and participating in this conversation) are all perfectly well aware of (they have been trotted out for time and again on just about every forum since the dawn of combat flight sims) - evidently because they weren't authored by Germans. Sounds like you have an issue to me.
  17. @Unreasonable - that should be reasonably simple to do. This weekend - time permitting - I will do it. I generally prefer to fly a mission with my mates than spend hours recording tracks and editing video for the benefit of people who will simply dismiss it as "feelings".
  18. I am talking about an exploit. I'd like the stabiliser to not perform as a magic elevator which performs as quickly at 700km/h as it does sitting on the hardstand. You should be free to use the stabiliser trim as much as and in whatever scenario you please - it just shouldn't work the way it does. This thread is about the stabiliser but I will bite: Regarding spotting, I personally find the current visibility to be OK. It seems a bit off when you are at altitude and looking at ground objects, but aircraft become visible at about the range they do in real life given their size. Regarding cheaters and choice of server - you are actually more likely to find cheats on the non-icons servers like WOL where the advantage conferred by the exploit is greater. I have tested stabiliser abuse and it gives you a MASSIVE advantage. When using it there is no area of the envelope where the 109 doesn't enjoy a clear superiority margin. I wasn't alive in WW2. I am an ex-Air Force pilot though. While that doesn't make me an expert on the 109 or any other aircraft I haven't personally flown, my "feelings" have more real world flying experience in comparably performing aircraft than most people here.
  19. I would dearly love to do this in a way that allows me to record all the FM parameters but I haven't yet found a way. I have made the request a couple of times in the appropriate forum for us to be able to output this data either to a file or over UDP but the devs have no interest in it. The best I can do is record a track and then analyse the video but without numbers no interpretation of the results will ever be accepted by some. My claims are based on observations in MP. At first I was puzzled by aircraft performance that just didn't make sense but I put it down to lag, or me misreading initial energy state or whatever. But when it kept happening over and over and I was able to view the entire engagement I became suspicious. So I tried it myself flying the 109 (I tested the F specifically) and was easily able to game the FM by treating the stabiliser like a hyper-elevator. I tried both mapping it to its own axis and to the joystick Y axis. I also had success simultaneously binding it to both the joystick Y axis and an axis on my Warthog throttle allowing me to have hyper elevator without geramos' issue.
  20. No - nothing that threatens your wishful visions of unassailable German superiority matters much. We do know the condition they were in. Funnily enough it was documented at the same time as the test reports - who'da thunk it - as were the precise details of their operation. I haven't linked anything in this thread because I've already done so before in other threads on this forum on the very same topic. I could go and find them again for you but I have a job and if you really care you can go find them yourself.
  21. You couldn't figure it out and from that representative sample set of ... one... you deduce that it must not be possible. We can do all of that in your thread entitled "Stuff that I think is wrong with VVS aircraft". This line of retort is like saying "its ok to cheat on my test because the other guy did it too".
  22. The tactic you are incorrectly referring to was to push hard negative G and enter a steep dive, then execute an aileron roll and exit in the pursuer's blind spot. The point of the negative G was to take advantage of the DB's fuel injection. Until Schilling's orifice was retrofitted to the Merlin the carburettor float would not deal well with negative G causing fuel starvation, making it difficult for Allied aircraft, with their carbureted engines, to follow. Emphasis on dive entry. The point of the dive entry was the negative G not to continue a steep dive and pull out on the deck. Another tactic was to shallow the dive after the initial entry and use the 109s superior acceleration downhill to extend. This didn't work so well against jugs which go downhill like a cannonball
  23. Here's what would happen ... 1. Nose over into a steep dive 2. Airspeed increases making the nose want to pitch up 3. You trim nose down 4. Repeat 2 & 3 a few times 5. You reach 650km/h and the ground is rushing up at you 6. You chop the throttle and pull back on the stick but it just won't budge 7. You try your damnedest to turn the stab wheel but it might as well be welded there 8. You die Here's what happens in the game ... 1 - 5 as above 6. You flick the stab trim full aft (if bound to a slider - some just pull back on the stick and have both elevator and stabiliser move) 7. The 109 performs something reminiscent of Pugachev's cobra 8. You go from 20,000f/m descent to easily pull vertical again behind the Yak that saw you diving and waited to pull up until you couldn't possibly make the pitch rate required to follow You ignored the bit where the 109 doesn't stall. And I've never mentioned the "trim on a slider". The Yak can't do it because it shouldn't happen. Regarding the P40 - I have already been corrected thanks. I do try to get the facts right but sometimes we slip up - I was thinking of the ailerons for some reason - probably because I map them to the same coolie hat, not having a trim wheel next to my seat. I was pretty obviously talking only about trim tabs. Given the context it was also clear that Moach was - not sure why you think he was talking about the primary control surfaces.
  24. I'm crystal clear about what I'm referring to - the 109 stab isn't magical - it has operating limits just like all other control surfaces. The P40 does not have a variable incidence tailplane - it uses trim tabs actuated by electric motors.
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