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Thread: Thunderbolt

  1. #26
    Hello Aleatorylamp,

    So far, this project is following the regular pattern.
    What looks like a simple and easy update turns out to be much more complicated than expected.

    From the "Conspicuous by Their Absence" Thread, I will quote a rather arrogant and foolish statement:

    Quote Originally Posted by Ivan View Post
    Hello Aleatorylamp,

    Even if you do not edit the MDL for FS 98, the mapping of the textures will not change when I update the model,
    so even with the current MDL, there should be no limitations on re-texturing even if it is an issue for a release.

    - Ivan.
    Some things just don't hold up to close scrutiny.

    Upon further examination, I am finding that the texture mapping has some wacky effects.
    There are places where some of the mapping does not make sense and others where there are textures that bleed from one piece to another. The only reason that they don't seem to affect the appearance in the simulator is because this is basically a single colour paint scheme. There are other minor problems with laying out symmetrical textures which hopefully will also get addressed.

    I will need to add at least one new texture file anyway, so it makes sense to move things around now to correct the minor bleeds and highlights (white background bleeding onto the piece). I remember now that I knew this was happening and that is why the empty spaces in the texture files are all white. The effect was supposed to resemble reflected light.

    - Ivan.

  2. #27
    Hello Ivan,
    Not to worry. Obviously, the comment about textures being unaffected would
    only be applicable to minor changes, and the situation is different now,
    so I wouldn´t say it was either arrogant or foolish.

    My Dad used to say:
    "Firstly, things happen differently, and secondly, than what one expects."

    The updated model will be a different one, and once it is ready, should Udo want
    to make updated Dottie Mae textures for it, it can be done separately. For the
    he is very busy workwise, and I have no news as to his progress. He also
    wanted to prepare two unarmed Ju52´s for FS98, so I don´t know how he´s doing.

    Anyway, we´ll take it as it comes - don´t let it disturb you!
    "Why make it simple if you can also make it complicated?"

  3. #28
    Hello Aleatorylamp,

    Here is a little history....
    Back in 2002, my second child was born.
    When the second child (my Son) came along, I had to give up my hobby of plastic modelling.
    With two children and two parents, all hobbies had to be instantly interruptible.

    A conversation might go like this:

    Michael is crying, can you check his diaper! (Note that this is NOT a question.)

    I need to hold these pieces together for a couple minutes while the glue sets!
    I need to clean my brushes first! (Exclamations because it is difficult to be heard over a crying baby if you don't yell.)
    Can you go check him?

    No, I am giving your Daughter a bath!


    Two or three hours later, after figuring out why there was a general baby fault, I come back to a couple dried paint brushes and paint jars or a part that sagged and isn't on straight.
    After a few of those events, I realised that I could not continue that hobby while the kids were small and needed attention.

    A little while after that is when I started building aeroplanes for Combat Flight Simulator.
    This Thunderbolt was done about a year after I started building and was probably the fourth or fifth project and at this point the lack of experience shows up in a few places. I am finding many of those issues now with the project as I attempt to update it.

    - Ivan.

  4. #29
    Hello Ivan,
    Well, thank God that with AF99 et al (SCASM, AA, etc.) you don´t
    get glue
    or paint drying up when you´re interrupted - although you
    do loose concentration...

    So now with the older kids there´s more time, and also, with the
    greater amount of more exact information available I ´m sure that
    re-taking the Thunderbolt for further attention will be an enjoyable
    and well worth-while challenge.

    "Why make it simple if you can also make it complicated?"

  5. #30

    Remapping Textures

    Hello Folks,
    The remapping of textures is going fairly slowly but it is progressing.
    Most of the "necessary" changes have been made at this point.
    There are only a couple more items that need to be moved around between texture files.
    The number of texture files has gone from 11 to 15.

    The appearance of the model is almost exactly as it was before I started.....

    One might wonder why I would go through this effort to remap textures when the overall appearance remains the same.
    The main reason is that I want to be able to easily develop more versions of the Thunderbolt and the current mapping only worked for the current versions.

    The first indication that I would need at least one extra texture file was when the Propeller Hub and Fairing did not fit into any of the other texture files without colliding with something else. In the Razorback's textures, there simply was no room at all.

    Next, this rework is intended to represent the P-47D-25.
    Early versions of the Thunderbolt mostly had disk wheel covers as shown on my current models.
    Later versions tended to leave off the wheel covers and show spoked wheels.
    The current version uses just one pair of textures to represent both Main Wheels, so the inboard and outboard textures need to be identical.
    There was no room for another Main Wheel texture.

    Current build standards also require an internal Canopy Frame which needs its own texture.

    Just as in the case of the Main Wheels, the Tail Gear Doors shared textures.
    This meant that the inboard side of each door had to be the same as the outboard side.
    This prevents applying Zinc Chromate as a corrosion inhibitor to the interior of the doors.
    There is a much worse problem though.
    On a monochrome all gray aeroplane, everything looks fine but if someone wanted to apply a contrasting colour to the underside of the tail, the interior of the doors would also get coloured the same way.
    Stripes on the inside of the Tail Gear Doors would look pretty silly.

    The P-47D-30 had Dive Recovery Flaps installed. Additional texture space for these Dive Flaps would have been easy even with the exiting texture files.

    Starting with the P-47D-40, a Fin Fillet was added to increase directional stability. This was often retrofitted to older machines.
    The Fin Fillet on some versions appears to extend from the Fin to the rear of the Canopy which means that there needs to be texture space for an object that is up to 10.5 feet long.

    The last version of the Thunderbolt, the P-47N, had a much longer Wing Center section to accommodate additional internal fuel tanks.
    While the texture files for the Inner Wing would allow for the stretch, the Flaps were mapped in such a way that there was no additional room and any stretching would need a remap anyway because the outboard edge was on the edge of the texture file.

    If I intend to build more versions of the Thunderbolt, my choice would have been to make changes as I needed them at which point there would be substantial differences in mapping between each version or to make all the anticipated changes at this point and only adjust textures for different versions. There will always be some differences in mapping between the Razorback and Bubble Top versions that are unavoidable because the pieces are so different between the two versions.

    The attached screenshot shows a mostly successful update.
    I seem to have forgotten to move the mapping for the Aileron Trim Tab.

    - Ivan.
    Attached Thumbnails Attached Thumbnails P47D25_TrimTab.jpg  

  6. #31
    Hello Ivan,
    So it´s getting even better than what we thought before.
    Sounds excellent! ...even though it seems rather more complicated
    than initially expected.

    For the new metallic texture issue, there´s absolutely no hurry anyway.
    Udo is under such work pressure, that it´ll be a while yet before he can
    start work on the new Dottie Mae textures.

    "Why make it simple if you can also make it complicated?"

  7. #32
    Hello Aleatorylamp,

    Actually I really wasn't concerned about Udo's "Dottie Mae".
    He has his canvas and that is really the end of my involvement on that project.

    As I commented in my prior post, there actually will be no really significant visual changes other than Zinc Chromate on the Tail Gear Doors and possibly a set of spoked Main Wheels.
    The changes are mostly for greater ease in building future Thunderbolt projects.
    These are the kinds of things I do on current projects in the planning stage, but back in 2003, these were not issues I was thinking about.

    There are a bunch more small changes that also probably won't be noticeable unless I point them out but as the plastic modelers say:
    "I'll know they are there!"

    - Ivan.

  8. #33
    Hello Ivan,
    Not to worry! I know the changes are more for future variants
    you are planning, not for Udo´s planned new textures.
    I only mentioned it just in case it was causing some hassle.
    Anyway, I´ll upload the existing model with new textures once
    they are done, whenever that may be!!
    "Why make it simple if you can also make it complicated?"

  9. #34
    As mentioned before, the visible differences will be minor.
    Here is a comparison between the original texture mapping and the new texture mapping.
    The two difference are the Tail Gear Doors and the Main Wheels.

    The Wheel textures actually took two tries. I made up a set last night and was planning to overlay them onto the appropriate files this evening. Unfortunately, I managed to do something stupid and overwrote them on the flash drive before I could use them.
    They were not that hard to redo but the original version was slightly better.

    In the earlier version, if a spoke texture was applied to the inboard side of the Port Wheel, it would also appear on the outboard side of the Starboard Wheel. This would not work well because the inboard and outboard sides are different when the hubs are not covered with a flat plate.

    Many little things still left to do before starting on the revised Flight Model.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Thunderbolt_LRTexture.jpg   P47D25_Propeller.jpg  

  10. #35
    Hello All,

    Last night, after poking around in another project for a while, I decided to take the D-25 Thunderbolt up for a bit of "Fun Flying".

    As some folks may already know, the old Development Computer I had been using died recently with what appears to be a failed Motherboard. It had been having intermittent errors and Video and I/O lockups for a while before it finally died.
    One of the big problems with working on the D-25 version of the Thunderbolt was that the Aircraft Factory 99 / Aircraft Animator combination would not always generate a useable model and Combat Flight Simulator would often crash or lockup for no apparent reason.

    Until last night, I thought I had a clean build for the D-25 but the first Screenshot shows otherwise.
    The rebuild cycle was actually quite fast with the updated Development Computer and things look a it better on the second Screenshot.

    I also made a minor adjustment to the AIR file, but that subject is worthy of a new Thread.

    - Ivan.
    Attached Thumbnails Attached Thumbnails P-47D-25_TurboOops.jpg   P-47D-25_TurboFixed.jpg  

  11. #36

    Smilo's Hammer

    Quote Originally Posted by smilo View Post
    i'm still happy to have the visual update
    and will wait for the air file improvements.
    as you said, it's been a long time.
    so long in fact, "smilo's hammer"
    has left my memory banks.
    sorry, i don't remember it.
    Hello Smilo,

    Last night, I was working on my version of Eric Johnson's P-39D and was looking for the some files.
    Ivan's Workshop is a very large place and there are many places that don't get visited very often.
    In a remote storage area of the Workshop, I found a crate with an interesting label on it.
    It was too small to contain a complete Aeroplane or Project but looked like a bunch of pieces to a Razorback Thunderbolt.
    The pieces were to a very old (probably initial release) of the P-47D-23 Thunderbolt which has been out of production for a very long time.
    This was around 2:00 AM, so my Engineers and Technicians were all rather annoyed when I called them up to see what could be done with what we had.
    Although that particular D-23 was out of production, the team looked to see if those old pieces could be completed with spares from the current (soon to be replaced) P-47D-23.

    The current production airframe parts actually fit without any great problems and the result is what can be seen in the screenshots.

    Not all the correct pieces have been located yet.
    No one wanted to hang around for more than a general "Proof of Concept".
    Armament and wiring for the Instrument Panel are not yet complete.
    The Factory Test Pilots are also complainng that this Aeroplane does not have a correct standard Canopy Interior or the current standard "Alpha-Glass" Canopy for better visibility.

    This really is a beautiful model and all I can really claim is that I provided the canvas for the artwork.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Hammer1.jpg   Hammer2.jpg   Hammer3.jpg  

  12. #37

    Changing Standards

    One of the details that is visible in the textures for "Smilo's Hammer" is that the textures for the inboard and outboard sides of the Main Wheels are the same. On my original model, the inboard side was covered by a disc and looked about the same as the outboard. On this model (and on the P-47D-25), the inboard side of the wheels do not have a cover and the spokes are exposed. The outboard side of the main wheels does not show spokes in any version.

    This was one of the reasons the textures needed to be rearranged. The original wheel texture was shared for both the inboard and outboard sides.

    One of the other things that was missing was the Interior of the Canopy Frame.
    The first screenshot shows the modified version which is dimensioned slightly different from the exterior Canopy Frame.
    It needs to be different because sometimes polygons that line up well in an Exterior view do not line up as well on an Interior view.
    Once the displayed Component looks good from the inside, it is switched from "Regular" to "Smooth".
    The switch to "Smooth" causes the interior of each Part to disappear and only the outside Parts remain visible.
    The next step is to run a program to reverse the facing of each Part so that it face inward instead of outward.

    The second screenshot shows the interior view after the flipping of the Component is done.

    The third screenshot shows the exterior view of the Component that now has no outward facing polygons.
    This is always an odd thing to look at. It appears to be facing in a direction that it is not. Not many things in the physical world have an inside but not an outside.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Razorback_CanopyFrame.jpg   CanopyFrame_Flipped_Interior.jpg   CanopyFrame_Flipped_Exterior.jpg  

  13. #38

    Canopy Frame Installed

    Installing the Canopy Frame was fairly easy.
    The result should be usable even if the textures are remapped at some later date.
    The colour switch to "Interior Green" or Zinc Chromate was just a matter of mapping to a different file from the External Canopy Frame; The offsets are actually the same which makes testing easier.

    Next come some Panel, Checklist, and Flight Model changes.

    - Ivan.
    Attached Thumbnails Attached Thumbnails CanopyFrame_Installed.jpg   Small_Pinch.jpg   UnPinched.jpg  

  14. #39

    Pulls to the Right....

    One of the odd things about my P-47D-23 is that it has (now had) a tendency to bank and pull to the Right.
    Banking and pullng to the Left is expected as a result of Engine Torque effects.
    I had noted that this was happening years ago when I last worked on this aeroplane and never did find a solution to what had to be a broken AIR file.

    A couple days ago, I was waiting for something and had nothing better to do, so I decided to list the possibilities as to what could possibly cause this situation and how to go about testing and finding the problem. I am not claiming any great knowledge of what can be done in CFS, but here are the things that occurred to me:

    1. There are some Aerodynamic effects in the AIR file that are asymmetrical that should not be that way.
    Years ago, when I first began working with AIR files, there was a very involved discussion about what could be done in CFS to simulate Propellers that rotated in a direction opposite to what we have come to expect.
    It is even mentioned on the Game Box that this issue was addressed though I had never found an example of a Flight Model that actually appeared to have a reverse rotation Proeller.
    Many thing were suggested. None of them actually worked. Sometimes the resulting changes were so damaging that the simulator would not load them.

    There was the possibility that there are some side force parameters that are incorrect
    The Engine location may have been specified incorrectly.

    2. The Weight of something on the Aeroplane was offset to the Right.
    Perhaps a Fuel Tank had a lateral offset. Both tanks on the Thunderbolt should be on the center line.
    I could not think of any other weights that could be adjusted in the AIR file.
    Later it occurred to me that the AIR file was not the only place where weights could be configured.
    The DP file might have a Gun Position set incorrectly or be defaulting to a Bomb carried off center.

    3. Also in the AIR file are many Mach effects tables. By themselves it was unlikely that they would be specifying a directional force to one side but perhaps there was a factor that was being amplified by another asymmetrical force such as Engine Torque or Rolling moment.

    The P-47D-23 Razorback AIR file is almost identical to that of the P-47D-27 Bubbletop.
    The first test was to see how the D-27 behaved.
    It did the typical "Roll to the Left" thing.
    That told me that if the issue was in the AIR file, it wasn't going to be something elaborate but a simple fat-fingered parameter somewhere. There are SOME differences between the two versions, but this was a pretty good indication that the problem was probably not in the AIR file.

    The next test didn't even require leaving the simulator.
    If the problem was in the ammunition load, firing it all off should correct it.
    Thunderbolts carry 400 rounds per gun so a continuous burst at the invisible Gremlins lasted a bit over 30 seconds.
    When the ammunition was gone, the D-23 slowly Rolled to the Left.

    Next step was simple: Figure out whether the Right side was loaded with super heavy ammunition or whether the Left side had super light ammunition.
    The result was that the ammunition in the Left Wing had Zero Weight.
    It sure is amazing stuff! Must be made of Unobtanium.

    - Ivan.

  15. #40

    This was Supposed to be SIMPLE!

    Hello All,

    It has been an amazingly busy month!
    After correcting the ammunition weight in the DP file, I thought I was close to done.
    The basic handling of the D-23 Razorback is actually fairly good, so I figured that updates to the AIR file would be fairly simple.
    These turned out to be famous last words yet again.

    This was one of those cases that I found that my knowledge of AIR files is somewhat inadequate to make the adjustments that I wanted. I found out that some of the values that I was "Tuning" really had no effect at all. The Wing Center of Lift appears to be a FS98 vestige and while the later simulators use Record 1534 for the same purpose, none of the stock CFS AIR files have this nor do they respond when such a record is added. There are obviously other ways that I can attempt to create the same effect, but those are a bit more complicated and would require some experiments and creating a spreadsheet for the calculations.

    The DP file also turned out not to be quite as simple as I had thought.
    Many sources list the P-47 Thunderbolt as carrying 8 x .50 Cal M2 Machine Guns with 425 rounds per gun.
    I was finding that the weight totals in my spreadsheet were coming up way too heavy and traced it down to ammunition load.
    As it turns out, the "standard" ammunition load tended to vary depending on the aircraft model but to match the maximum ammunition weight (which also included ammunition considered to be Alternative Load) as listed in America's Hundred Thousand, each gun would only be loaded with 275 rounds.

    The DP file was modified for 275 rounds as default with 425 rounds optional.
    This default ammunition load was used for performance testing.

    Tuning the Roll Rate also turned out to be unexpectedly difficult.
    While I could easily adjust the Roll Rate, I had a rather tough time getting the Rates to match the Airspeeds as specified.
    It got bad enough that I spent an evening working on a spreadsheet to predict the roll rates at each speed.
    With the numbers I got from that spreadsheet, I found that I had to plug in numbers that were entirely non-intuitive in order to get the performance that I was looking for. (The numbers were really not exact but more an indication of where to go.)

    The next thing I found was that the DP file weights for Rockets and Bombs were also quite a bit different from what they should be.

    In order to address some of the issues I was finding in the AIR file, I started adding a bunch more record descriptions to the FDE Control File. That ended about a week ago when FDE complained that the control file was too complicated and barfed. I had to revert to the last saved FDE Control File and now some of the more obscure records are being edited with AirEd which doesn't do well with conversion factors.

    At this point, many of the issues have been addressed if not resolved and performance and handling are about 90% of where I want them to be. The technicians from Ivan's Propeller Shop have been a bit busy elsewhere, so there won't be any work on a new Propeller for any of the Thunderbolts for a while.
    Propellers are tedious to build, but the process is pretty well defined. I believe time is better spent in trying to pin down things that are not quite so well defined.

    Specifications and Performance thus far (for the P-47D-23):
    Empty Weight ----- 9956.7 pounds
    Basic Weight ------ 10545.1 pounds
    Gross Weight ----- 13582.1 pounds

    Zero Fuel Weight - 11003 pounds

    Speed @ 500 feet ------ 328 MPH (Military Power)
    Speed @ 25,500 feet -- 433 MPH (Military Power)

    Service Ceiling ---------- 41,600 feet

    The performance will most likely change slightly if a new Propeller is installed.

    - Ivan.

  16. #41

    Weapons Loads

    With the default weapons loads, the Gross Weight of the P-47D-23 for CFS would be 13,497 pounds which is about 85 pounds below the gross weight of the actual aircraft. The difference is accounted for by partial loads of Engine Oil and Anti-Detonant which would be consumed during the flight but are not accounted for in the disposable loads.

    With full ammunition, bombs, and rockets, the maximum take-off weight of 17,400 pounds may be exceeded by around 500 pounds.
    At maximum take-off weight, the island airstrip that is typically used for testing gets to be a bit short even with flaps and emergency power.

    Screenshot shows a low pass by the aircraft currently being used for testing.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Hammer.jpg  

  17. #42
    Repairs on Smilo's Hammer are complete and uploaded.

    Time to do some more testing on the current P-47D-23 model.

    - Ivan.
    Attached Thumbnails Attached Thumbnails SmilosHammerV2.jpg  

  18. #43

    A Cool Movie

    Starring the Republic P-47D Thunderbolt (Bubbletop) and co-starring the Messerschmitt Me-51 Mustang.
    There were a few human actors as well.

    - Ivan.

  19. #44
    The P-47D-25 is back in the Workshop after a fairly long break.
    The most recent work has been to add a couple extra pieces and redo the animation of the Main Gear.

    The First Screenshot shows the final sequence as the Gear Doors close.
    The Second Screenshot shows the internal Canopy Frame before it has been flipped inside out.
    Note that in this screenshot, the Component is "Sharp".
    The highlights got a bit distracting and they were even worse from an interior view, so in the "final" version, they were made "Smooth".

    The Third and Fourth Screenshots show the interior view of the Canopy Frame after it has been flipped.
    The shapes are passable, but still not completely right, so there may be yet another version shortly.

    Attached Thumbnails Attached Thumbnails LandingGear_New_Parts.jpg   CFrame_Sharp.jpg   IFrame.jpg   IFrame2.jpg  

  20. #45

    Panel Differences

    The attached Screenshot shows the Panel I have been using for all Thunderbolts.
    The background is obvious for a Razorback aircraft (P-47D-23 and earlier) and needs some changes to look more like what is found in the D-25 and other Bubbletops.

    One other feature worthy of note is the Fuel Gauge.
    The stock gauge is intended for a Main Tank of about 200 Gallons capacity (actual is 205 Gallons) and Auxiliary Tank of about 100 Gallons capacity.
    Although the Aux tank did not change, the Main Tank increased in size from 205 Gallons to 270 Gallons starting with the P-47D-25 series.
    A new Fuel Gauge would seem appropriate.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Razorback_Panel.jpg  

  21. #46

    P-47 Fuel System Differences

    The attached diagrams show the differences between the fuel systems in the early and late D model Thunderbolt.
    The stock fuel gauge is clearly incapable of reading the larger quantity.

    - Ivan.
    Attached Thumbnails Attached Thumbnails P-47_FuelSystemLate.jpg   P-47_FuelSystemEarly.jpg  

  22. #47
    Attached is a screenshot of the updated panel and fuel gauge (50% fuel load) for the P-47D-25.
    The pointer for the Main Tank is slightly below the mark for 150 Gallons which seems appropriate for 135 Gallons.
    Actually this panel is being shown on the P-47D-27 which also got an internal Canopy Frame this morning.
    It is pretty much the same for all the Bubble Top P-47 with the exception of the P-47N which carried a couple more fuel tanks and gauges for them.

    The next steps are to edit the AIR File for Compressibility Effects which were tested on Smilo's Hammer and to build a Propeller Table.
    Earlier versions did not have Compressibility Effects that matched the aircraft manual's descriptions.

    - Ivan.
    Attached Thumbnails Attached Thumbnails 50%Fuel.jpg  

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