Conspicuous by Their Absence - Page 44
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Thread: Conspicuous by Their Absence

  1. #1076

    Props tailor-made for a given plane

    Hi Ivan,
    It would really be cool to be able to tailor-make decent props for a given plane more easily!
    The pictures of graphs in your posts are generated by your spread-sheet, I suppose... It also helps to visualize whatīs going on.
    The non-linear graph sounds logical, as it would save on points where it was more of a straight line so as to use them to smooth out more curved places.
    Good night!
    Aleatorylamp

  2. #1077

    Something broke?

    Hi Ivan,
    I believe sometimes something inside an .air file "breaks" while preparing it, so Iīll transfer everything into a new one. The altitude thing is still off, whatever I do, and it was bang-on before, so it must be that!

    Edited update 2 hours later:
    Strange... The brand-new .air file showed exactly the same flaw, but unlike the previous one, this time it has allowed a small increment in Boost Gain (as you had suggested) to place peak-power at the correct altitude very nicely.

    The ways of the .air file are inescrutable... Maybe it does it on purpose to keep us on our toes?

    So, on with the fun!
    Cheers,
    Aleatorylamp
    Last edited by aleatorylamp; March 10th, 2015 at 01:24. Reason: updated info

  3. #1078

    Giant: Great performance results!

    Hi Ivan,
    Thanks to your guidance and proverbial pacience, after all this work of adjusting and tuning, and then re-adjusting again and again as new factors cropped up, I have finally managed to get the Giantīs .air file into a completely different state altogether. It is actually doing what it is supposed to do!

    The last hurdle was re-adjusting Drag to adjust descent and approach so that landings could be viable. With that, the excessive RoC higher up also automatically corrected itself, although performance near and at the ceiling is quite poor unless tanks are half empty.

    With this, the Giant is finished now! It has definitely been worth while, and the improvements have even been quite a bit greater than what I had initially expected. The only thing I havenīt been able to do after some improvements on the model itself, is to SCASM the virtual cockpit again, as the necessary programs to do so wonīt work on my computer.

    However, the virtual cockpit back wall is adjusted so that it wonīt block the padlocked chase-view, and the fact that the virtual cockpit itself disappears is not altogether a disadvantage, because it allows the locked enemy to remain visible, otherwise hidden by the interior-view cockpit walls.

    So! Now Iīll tune the other Giant with the darker textures, the triple fin and the more expensive Maybach engines to do what itīs supposed to do too, and Iīll be able to upload the planes shortly!
    Cheers,
    Aleatorylamp

  4. #1079

    Flying the Giant

    Hello Aleatorylamp,

    Glad you are satisfied with how the Giant flies.
    I have never been completely satisfied with any of the flight models I have worked on and most of the time it is because of handling issues rather than straight line performance.
    I just quit messing when I have exhausted what I "know" how to do or when it is likely I will mess things up more than fix things.

    Way back when I was heavily into writing utilities to use for CFS Development, I wrote a short little C program to generate all the possible fuel tanks in an AIR file that did nothing else. It gave me a reliable source to copy records for fuel tanks for a new AIR file. FDE would not do the copying but AirEd would.

    From there, since I pretty much understood the structure of the AIR file if not the contents, I wrote another program to dump all the records from the AIR file in hexadecimal but with each record separated with heading.
    That utility would let me dump two AIR files and compare the text files and be able to tell WHERE the differences were if there were any. I could not tell what the differences were, but knowing where to look was enough information for a regular AIR file editor to be useful.
    I wish I knew where I put that program....

    I will see if I can find some notes that might be useful for your Giant's V Cockpit.

    - Ivan.

  5. #1080

    Propeller Tables

    A quick patch to prevent the perpetual motion effects in the Mustang's Propeller is not hard to do.
    Attached are screenshots showing the Power Coefficient Table and the Revised Propeller Efficiency Table.

    The thing to look for is that at no point should the efficiency be non-zero when the power coefficient is negative.
    The revised Table 511 does not quite satisfy that requirement, but the overlaps are very small and hopefully transient enough not to cause problems.

    The bigger issue is still that the maximum advance ratio is still too low.
    Consider that with the current efficiency table, the propeller efficiency does not change above 400 MPH and I believe that some of the values there are a bit too high.

    At this point, the limitations are that it is difficult to generate a smooth curve with points spaced further apart and my very limited understanding of MS Excel that I am attempting to use to generate new tables.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Record512_P-51D.jpg   Record511_P-51D_Revised.jpg  

  6. #1081

    Flight model satisfaction

    Hi Ivan,
    Itīs interesting that you know how to make useful programs - they come in handy! I can only program in QBASIC, and itīs a bit obsolete now... I havenīt learnt to use spread sheets either, so Iīm limited to manual entries in AirEd, but itīs not too bad at all with CFS1!
    To compare 2 .air files I always open 2 windows with AirEd open side by side, and go down both listings in order, and it works OK.

    After the FS98 limitations that I have been used to until now, it is indeed satisfying to experience the increased control that CFS1 offers over aircraft performance! The main problems I ran into towards the end were my own fault, as I should have noticed that the .air file had something "broken" in it and renewed it long before. Anyway, I have just adjusted the second Giantīs better engines for 8200 ft rated altitude, and Hp is fine all round... Iīm now adjusting RoC for different altitudes.

    You mention fuel tanks: An interesting thing on the Giant was that it was fuel-trimmed. Prior to take-off, the angle of attack for the sustaining tailplane was set from outside, depending on the bombload to be carried, and then the plane was tanked up, always leaving the 2 foremost of the cylindrical inboard fuselage tanks empty. The Mercedes engined Giant had 8 tanks, and the Maybach one, 10. This way the plane was trimmed for take-off and climb. Then during flight, the fuel engineer could pump fuel into the two foremost tanks to change the CoG for level flight. He also kept the central tank under the top wing full to feed the engines.

    A trimming-wheel was also available - it is visible on cockpit photos, but only used when the plane was empty and low on fuel, and there was nothing to pump into the forward tanks to lower the nose.
    Anyway, in CFS thereīs no fuel menu, so one canīt move the fuel around from one tank to another and the trimming wheel has to be used. For CFS1 I have only defined 2 fuel tanks, left and right, each with half the total fuel.

    Iīll wait a bit for your notes on the V-Cockpit then, before I upload the Mercedes Giant.
    Cheers,
    Aleatorylamp

  7. #1082

    Broken?

    Silly question, but if a side-by-side comparison of two AIR files isn't difficult, then why not figure out what was Broken in the AIR file and fix it rather than throw it away and start over? I find it to be tedious and very error prone to compare long files.
    That is why I prefer to let machines do the text searches and matching for me.

    By the way, Just a few minutes ago, I generated my first spreadsheet calculated Propeller Power Coefficient Table (512).
    Though the curves are programmatically generated, the adjustments to curve parameters need to be entered by hand.
    Actually only the positive values are tuned so easily. The negative side is also formula generated, but the formula is not easily tuned.

    Now I just need to build a matching Propeller Efficiency Table (511) to test.

    - Ivan.

  8. #1083

    Invisible Breakage

    Hi Ivan,

    Congratulations on your Propeller Making Machine! I bet that real propeller makers would love such a tool. Connect it to a computer and out comes a new propeller! Ferhaps in the future with a 3D printer! They have already printed a flyable 3-ft-wingspan plastic radio controlled model aeroplane!

    .airfile breakages:
    Maybe itīs a silly answer, but as far as I know, from what I have read (i.e. Tom Goodrick and Guder, and comments from my previous and retired FS98 .air file writer), the things that "break" are internal "mechanisms", not a parameter visible in the FD editor listing. Otherwise, after going systematically down through the newly loaded and conveniently re-named P51D airfile, and manually transferring the pertinent data from the "broken" .air file into the pristine new one, how else could it be that the unfixable flaw suddently disappears?

    Cheers,
    Aleatorylamp

  9. #1084

    Perpetual Motion

    I bet the actual aircraft builders would much rather have a self energizing perpetual motion propeller instead.
    I know *I* would prefer a real aeroplane that could fly around the planet with a single gallon of avgas.

    If you send me both good and broken AIR files, I am sure a hex dump could find the difference. If I could find my old program, it could tell in a minute or two what record the error was in as well.

    - Ivan.

  10. #1085

    FD breakages

    Hi Ivan,

    This is just to clarify that I must be wrong about broken .air files having undetectable flaws.
    I had thrown away the "broken" one I couldnīt fix, so I canīt send you the file or test it, but I had one from a few hours prior to the "breakage".

    I took it and put all the new parameters in there, and the .air file works fine! So, you must be right about the fact that a flaw CAN be found in an .air file, i.e. it isnīt an "invisible" internal thing that may break. It must have been something Iīd done to it, obviously.

    Perhaps Tom Goodrick and Guderīs comments about having to use a fresh .air file to start anew when problems become unfixable, referred to an accummulation of erroneous entries that were too difficult to put right, and it was easier to start afresh.

    Anyway, itīs not a problem. What is a problem is that SCASM run from MDLDisAs V3.05 refuses to compile a new .md file due to errors, and I canīt get hold of the older V2.01 which as Hubbabubba says, seems to report fewer errors. I was reading the thread on the SCASM tutorial in Hubbabubbaīs corner, but I canīt test anything as my version wonīt work properly.

    Anyway, if the virtual cockpit canīt be fixed, I donīt really mind, itīs not so serious, and I donīt want to cause so much bother. If course, if thereīs light at the end of the tunnel, then Iīll try and make it work.

    Cheers,
    Aleatorylamp

  11. #1086
    Hello Aleatorylamp,

    Please do check your email. I found something very old that might be useful to you.

    Regarding Tom Goodrick and Rabbijah Guder: I don't believe I have seen anything recent from either of them. To me this means that their work and observations about AIR files was done at a time when there was much less knowledge available.
    A lot of their conclusions although logical for the evidence available at the time is no longer valid as we find out more about the structure and contents of AIR files.

    Another problem is that the AirEd.ini and FDECtrl.txt files which listed the "known" fields in the AIR file had much less content than they do now. That means that quite a lot of the AIR file was "invisible" to them.
    That is why I suggested doing a hex dump of the actual AIR file to see where the differences are. A hex dump should show EVERYTHING whether or not the record is known.
    I am quite glad that they did the poking around and reasoning and chose to document it because I started by reading their reports also. I also realised fairly quickly that a lot of their conclusions were a bit obsolete in light of then current knowledge and (recently) some releases of information by Microsoft.

    There is also the possibility that the AIR file editors they were using had bugs that would sometimes corrupt the file in a manner that was hard to fix.

    - Ivan.

  12. #1087
    Hi Ivan,
    OK, good explanation! Thank you very much.
    Some things evolve, and other things become obsolete and no longer apply.
    Thatīs good - with modernized tools CFS1 wonīt become obsolete for some time yet!
    Another good thing is that some people know, and can spread the knowledge!
    Cheers,
    Aleatorylamp

  13. #1088

    Disassembler and SCASM works now

    Hi Ivan,
    Thanks a million for your help! My SCASMing setup finally seems to be working.
    Iīm now going through the instructions you and Hubbabubba sent me, in order to join the .scx listings of the separate v-cockpit models to the .scx listings two v-cockpitless Giant models, so as to re-compile them afterwards.
    OK, then
    Cheers,
    Aleatorylamp

  14. #1089

    SCASM fixed Virtual Cockpit!!

    Hi Ivan,
    I can hardly believe it!! I inserted the V-Cockpit code into the Giantīs source file and the newly SCASMed virtual cockpit works perfectly!
    I also had a look into Hubbabubbaīs thread on AF99 colour codes in hexadecimal and with this info I was even able to find the individual cockpit parts in the source file and identify their vertices to eliminate some hairline cracks.
    The next step now is to simply put the V-Cockpit code into the other Giantīs source code and simply change the dark green cockpit parts to dark blue, and presto!, the other Giant will have a perfectly working Virtual cockpit too!
    Iīm just tweaking a few things in the .air file and will be uploading the planes soon!

    Who would have thought that an old dog could learn a new trick?
    Thanks a million!!
    Cheers,
    Aleatorylamp

  15. #1090

    Second Giant V-cockpit also SCASMed

    Hi again!
    The second Zeppelin Staaken R.VI, with the Maybach engines, now also has its SCASM-fixed V-Cockpit.
    This one has a slightly darkened night-bomber splinter-lozenge livery in dark-blue-blue-orange-red-grey with a blue cabinroof and blue interior window frames, whereas the Mercedes-Engined Giant has a green forward-fuselage and window-frames, and an overall brighter conspicuous anti-friendly fire colour scheme in green-red-orange-blue-dark blue.
    As soon as Iīve finished last minute adjustments on the .air file iīll upload them.
    Cheers,
    Aleatorylamp
    Attached Thumbnails Attached Thumbnails V-cockpit1.jpg   V-cockpit2.jpg  

  16. #1091

    Cool Looking Giant Aeroplane!

    Glad it all worked out for you.
    It does look cool from the screenshots.

    I have also made some progress with the Propeller Tables.
    Hopefully there will be something worth flight testing shortly.
    The candidate for flight testing is a Ki-61-Id that has been waiting its turn in the paint booth for years.

    - Ivan.

  17. #1092

    Volunteer for flight testing

    Hi Ivan,
    Tell me what youīre testing for and Iīll I volunteer for the task!
    Cheers,
    Aleatorylamp

  18. #1093

    Flight Testing a Propeller

    Thanks for the offer Aleatorylamp.

    I don't think this is a task that I can delegate though, especially not with the first try at Propeller Tables.
    I suspect testing this time will be a bit different from my usual protocol.

    My plan (very subject to change) is this for now:
    Gather enough information for a data sheet on the Kawasaki Ki-61-Id.
    I MIGHT already have this but can't tell right this moment because any data and references would be on the HDD for my dead laptop.
    (It would also help if I could remember where the notebook is that contains all my old test record sheets.)

    Run a full flight test on the Ki-61-Id (version 0.55) with the propeller as it currently stands.
    Engine Power at various altitudes
    Level Speed at various altitudes <-- This is the part that takes the longest
    Climb Rates
    Service Ceiling

    Also note the Propeller Pitch, Thrust, etc under various conditions.

    Tune the Propeller Tables via Spreadsheet.
    Plug in the new Records 511, 512.
    Re-Test.

    There ARE a couple new developments though.

    A replacement for my dead laptop was ordered last week and should arrive in a few days so I will have a place to load all the accumulated data from the old machine. Just need to figure out how to get license from the old MS Office and Anti-virus onto the new machine.

    I also found my command line Spreadsheet to AIR File record conversion program. It actually was written back in September 2010 from the date of the source code file. Now I just need to go over the program and make sure it does what I am expecting.

    Plenty of things to do.
    - Ivan.

  19. #1094

    Extensive plan of action

    Hi Ivan,
    I feared as much... It is an extensive and detailed plan of action.

    I know your plane is very different from the Giant, and requires different testing, but should you need a timed cruise-climbing test at a set elevator trim setting (or with minimal corrections along the way) from sea-level to ceiling, I could do it, noting down RoC, Mph-TAS, RPM and Hp, for every couple of thousand ft or whatever interval the higher climbing speed will allow. I could also do level flight testing for different altitudes - I know they take a bit of time as one has to wait for the plane to balance itself out, but itīs no big deal.

    So: Just in case you need it! Not a "Zwangsbeglückung" like the Germans say, i.e. an "obligation to be made happy". They like to make up words that require a whole phrase en English!

    Iīm glad about your laptop! Often they canīt be repaired for a reasonable price.
    Cheers,
    Aleatorylamp

  20. #1095

    Creating Test Protocols

    Hello Aleatorylamp,

    Thanks for the offer. It IS appreciated, but probably won't do me much good at the moment.

    First of all, the extent of testing varies quite a bit depending on how much information I really need.
    For example, the Me 109E Trop that was done a little while back had only the amount of testing necessary to give it the handling I THOUGHT a 109E should have and the basic straight line performance, climb rate and ceiling.
    This meant that I only did speed tests at 500 feet and around 15,000 feet (?). (I can't remember the exact altitude but it was wherever the engine power started to fall off.)

    On this test, I am guessing I will be doing speed runs with notes on propeller pitch and thrust EVERY 2,500 feet.
    There may be the need to record more numbers when things don't work as expected after the propeller is changed.
    Keep in mind also that I will most likely make changes to the propeller tables as I find things that don't quite work.

    The general flight model for the Ki-61-Id is also very much my interpretation from doing a fair amount of reading.
    The Allies tested captured examples at 348 MPH. There was a great reluctance to test at high power settings because of the perceived unreliability of the engine. (The total flight testing was very short duration and was terminated by a main bearing failure.)

    I believe that 380 MPH was closer to what the airframe really could achieve for the following reasons:
    IIRC, the Japanese claimed 367 MPH but their testing was probably done at a much lower power setting which was their usual practice.
    The Kawasaki engine was a "copy" of the Daimler Benz DB 601Aa but with local "improvements". It turned out that the improvements were mostly detrimental and the Japanese were not able to achieve the supercharger performance that the Germans had in the original.
    Also, this engine model was quite poorly made in general. Most were not reliable or could not achieve the output that was claimed. This fragility might explain their low Manifold Pressure limits at altitude which are well below their Take-Off and sea level settings.

    As we have already observed, my mechanics are much better trained than the typical Japanese Army mechanic. They have corrected the issues of unreliability that were so prevalent in these engines. The fuel we are using now is still only 92 octane but does not contain pine root oil or other extenders, so we are able to run these engines at the designed settings.

    - Ivan.

  21. #1096

    Testing

    Hi Ivan,
    How insteresting - there seems to have been a lot of "shared" technology going round then.
    Iīd agree with you, that there is not much point in CFS for using a below-par quality engine whose main bearing goes after a short test, so FD parameters would obviously be set to simulate a good example of the engine, if not on par with manufacturer specifications, then at least (or perhaps better) on par with reports by pilotīs of the time who actually flew them, as you said.
    I found that allied testing reports sometimes give confusing results, as has happened with British tests reports on the early German "overcompressed" engines. Often, the reported designation was not even correct, and as they didnīt really know how exactly they were to be operated, the testing conditions didnīt really fit the real engine performance. They did however seem to have been better at testing normal aero-engines, not of the "a" or "aü" type!
    Did you get the Mercedes-engined Giant I sent for a short final test last Wednesday? There could be some problem with e-mail traffic again.
    Cheers,
    Aleatorylamp

  22. #1097

    Concept question: Engine+Propeller+airframe=performance

    Hi Ivan,
    I have a concept question for you, as I canīt solve the balancing out of the parameters for the Maybach engined Giant, where Iīve been trying to adjust all the different parameters that affect power and speed.
    Either RPM is OK and Hp 25 hp too low, or RPM and climbing are too high and Hp correct. I was also re-adjusting the Propeller Efficiency and Thrust tables.

    On second thoughts now, I wonder if perhaps the propeller tables neednīt be touched, as these fit aircraft speeds rather than engine RPM or altitude. Perhaps, really only the Torque graph needs adjusting (with its dip 100 RPM before before full PRM), and the Friction Graph, after setting the compression and boost-gain parameters, of course.

    The aircraft is basically the same as the Mercedes engined one, except for 500 lb more dead weight (the engines were heavier), and the engines very similar, but better.

    Performancewise, the Maybach engined aircraft:
    a) higher compression: 233.83:1 instead of 200.6:1
    b) had a 1700 ft higher ceiling: 14,100 ft,
    c) got its full 245 Hp at 8200 ft as opposed to the otherīs which was 267 Hp at 4300 ft., (boost gain was 1.4 instead of 1.22), meaning that when the Mercedes engine got to the Maybachīs rated height, it had already lost a lot of its 267 Hp, and the Maybach one was at peak performance.
    d) was 3.5 mph faster at full speed level flight, with 84 mph TAS instead of 80.5
    e) average RoC was 328 fpm, 33 fpm higher than the otherīs 295 fpm
    f) Full RPM was 1400 instead of the otherīs 1450 RPM

    So the question is essentially:
    Can the 2 Propeller Tables in theory be left alone?

    Thanks in advance for your answer. No hurry!
    Cheers,
    Aleatorylamp

  23. #1098

    Adjustments

    Have you actually tuned the engine RPM setting in the AIR file?
    You should not be exceeding the RPM limit under normal flight conditions.

    As for what exactly is happening when RPM is too low but HP is correct or HP and Climb are too high if RPM is correct, I would actually need to test it myself to see what is happening.
    I have already told you the way I would do the tuning, so there is no other information I can give that is new.

    Please check your post in the area regarding Compression Ratio.... The numbers that are listed do not make sense.

    My guess is that with the difference in HP and RPM between the two engines, you will need to do some tuning in the propeller tables.

    My apologies for not giving much detail, but I can't visualise what is actually happening with just the numbers provided.

    - Ivan.

  24. #1099

    OOps!

    Hi Ivan,
    Iīm afraid that my migraines sometimes take their toll.
    I do apologize - it doesnīt make sense indeed! I meant to say:
    a) i) higher cylinder capacity: 233.83 instead of 200.6 cu. in.
    ii) higher compression rate: 6.08:1 as opposed to 4.94:1.
    The first thing Iīm trying for is to get the max. RPM right.
    Thanks for your answer on the propeller blades tables! That was really all I wanted for the moment, otherwise I would be too much of a bother. I shall proceed accordingly!
    The necessary friction graph setting is becoming enourmous: I had it at 100 and now itīs almost 250! It seems abnormal though, so Iīll see what can be done with the propeller tables.
    Thanks and cheers,
    Aleatorylamp

  25. #1100

    Propeller Tables

    My son happens to be working on Algebraic Functions in school and I showed him a couple tools I had used to work on the Table 512 template. We didn't actually get into the exact result and I don't know if he would even recognise the results in my spreadsheet, but he at least has the basis now to get to the same place.
    All of these computer tools and the Internet simply didn't exist when I was doing the same things in school.

    Now I just have to get him to WANT to figure out what I am doing..... That is a much harder task because Los Santos and Liberty City are much more appealing to him in comparison to plotting curves on a spreadsheet.
    "So what the heck does your spreadsheet have to do with playing Combat Flight Simulator???"

    He would much rather pilot a Pod Racer through a maze than flying the Warhawk through the Eiffel Tower.
    I still have not been able to get him to keep only one hand on the stick so that he can use the other for the throttle or other controls.

    Sometimes I wonder also if my time would have been better spent playing Sudoku. At least then my wife would not wonder all the time why I am playing on the game computers.

    - Ivan.

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