F-35 Project update

F-35A Final outer model for Beta release

While the Beta build is still not complete yet (I'm still adding MFD functionalities), I've finally managed to go through all the CR's from the Alpha and implement fixes where possible.
There is still some work to be done, but in any case I will release the Beta 1 the next weekend (even if it will only have the AA-1 model and still miss some of the MFD functionality).

Here are the changes implemented in response to the Alpha test feedback:

EXTERNAL MODEL

1. Nozzle animation incorrect -> Redone nozzle animation (but still linked to throttle)
2. Jaggies nearby the engine intake area -> Modified fuselage model, (but it is still slightly visible)
3. Excessive gap between engine nozzle and fuselage -> Modified geometry to get rid of the gap on AA-1 model (NOTE: AF-1 and subsequent planes have a different design)
4. Wheel/tires animation incorrect -> Fixed wheel parameters in .cfg file
5. Navigation lights missing -> Placed lights in .cfg file
6. Covers for auxiliary air intakes missing when using SHIFT+E+4 command. -> Modeled auxiliary air inlet cover, but I will not model additional ribbons and covers as I'm saving polys for the weapons model
7. Irregular bumps in the external model -> Redone fuselage geometry
8. Poor detail in the refuel receptacle -> Refuel receptacle modeled
9. Poor detail in the nose landing gear -> Redone most parts of the main gear and applied new textures.
10. AIM-120 not attached to hardpoints -> modeled hardpoints for AA-1 will model LAU-147 for operative model
11. Nose gear door detail/accuracy not good enough -> Redesigned hinge and added actuator and new texture
12. Request to model the lights in more detail -> No additional modeling (issues in Boolean operations geometry), but better texture. Miscellaneous other actions (not requested by testers)
13. Wrong size of main gear wheels / tires -> Modified model
14. Add detail to the main fuselage texture diffuse/spec/bump -> Enhanced textures
15. Fix mistake in texture UVW in the inner side of air intake -> Fixed
16. Add separate moving part for weapon door hinge - visible on real plane on closer inspection, not modeled -> Modeled (note:unsure if real design is changed in AF-1)
17. A/c is sitting rather low on the main gear. Changes to the animation sequence and contact points needed. -> Changed animations and .cfg file, a/c now sits correctly

To do list:

- Better afterburner effect

No action / CR reject:

-None-

VIRTUAL COCKPIT

NOTE: VC functionality has been completely redone with new custom HUD by Jivko Rusev and Scott Printz and new custom MFD - The list below covers only issues on the Alpha build that are applicable to Beta

1. Virtual cockpit frame rate low / excessive number of polygons -> Optimization led to a 15% reduction in polys and removal of 2 texture sheets
2. Minor texturing UWV misplacement on cockpit floor -> Fixed
3. VC night lighting too bright -> Changed .fx file
4. Incorrect tooltip showing "parking brake" in the battery area -> Fixed
5. Visual hole aboce the pedals (polygons missing) -> Fixed
6. "No Hold" texture stretched above ejection seat -> Fixed
7. Stick movement excessive if compared to real F-35 stick -> Fixed

To do list:

- Complete rework of the cockpit XML (80% done - Many MFD buttons/pages are now functional)

No action / CR reject:

- "patches" on the side of the Vc glass are unconnected to the canopy; Action: modify the Vc model -> No action. Unclear how the area looks like in reality.

- Explosivc cord not connected to glass -> No action. Better leave as is to avoid clipping.

FLIGHT MODEL

Note: special thanks to Roberto Leonardo for some of the fixes.

1. Excessive top speed -> Redone Wave drag table. Now it is approximately Mach 1.69
2. Weak brakes -> Fixed brakes effectiveness
3. Pitch changes depending on throttle setting -> Fixed/mitigated with new .air file
4. Pitch changes when activating virtual speedbrake -> Fixed/mitigated with new .air file
5. Low roll rate -> Fixed with new .cfg file
6. Excessive loss of energy during high-G turns -> Fixed with new .air file (may be slightly too good now?)
7. Virtual speedbrakes not much effective -> Fixed
8. A/c prone to yaw instability during takeoff run -> Mitigated (but not completely solved - further stabilization led to a behaviour unresponsive to rudder)
   

To do list:

-Nothing, awaiting Beta test

No action / CR reject:

- High AoA dynamics causes excessively low stall speed (75kts)-> No action - left as is not to screw landing behaviour (which seems good)

- Check landing attitude AoA -> No action. Landing behaviour seems good for most users

- Full flap deployment happens at low speed -> No action. Left under FSX automatic control as maneuver flaps

F-35 Lightning II - project update and some screenshots

F-35 AA-1 climbing nearby Edwards AFB (photoscenery made with FSET). Fuselage textures are now slightly more detailed - and for AA-1 I've added a "scorched" effect to the paint nearby the APU exhaust (as happened in the real AA-1 - AFAIK, exhaust has been moved to the lower side on all models except the -C for deck crew safety concerns...)

Testing low speed flight characteristics neaby Edwards AFB. So far so good. Most, if not all, of the issues in the Alpha build are solved and the plane flies smoothly and it is easy to fly (with thanks to Roberto Leonardo's tweaks especially in the tight turns department).

On of the major areas of improvement is the MFD which is now truly multifunctional, and allocates fewer texture sheets. Some of the MFD pages will be accurate to their real counterparts - some others will be less accurate but I'm confident that the final layout will be a reasonable compromise.

The general cockpit layout is accurate, with some exceptions and artistic licences here and there. For example the canopy frame is the "weight optimized" version - somewhat different from the actual AA-1. Another example is the lights panel, which sits where an emergency electrical panel should be. In geneal I've tried to balance accuracy, useability, graphics and...fun. Yes, I am one of those who still thinks that, afterall, it's just a videogame :-)

Last, but definitely not least, there is the new HMD by Jivko Rusev and Scott Printz. Basically Jivko has taken Scott's excellent F/A-18 HUD code and adapted it to the F-35. This new HMD gauge is as close as possible to real one (given the information publicly available) and it is a huge step forward in cockpit useability. Scott and Jivko have kindly provided the authorization to include it in the package - and looking at the screenshot I took I realize it does not do justice to their work... It looks awesome. Trust me.

Well... Above are some screens - as promised. I did not have much time to work on the F-35 lately, so the Beta is 10 days late... and the chances that I will be able to complete it before the next weekend are pretty small. I do not think I've much to add to what I wrote below the screenshots... but in short: the visual model is even more accurate, the flight model is better, the VC has more functionality and there is a great new HMD by Jivko Rusev and Scott Printz.

Now, I just hope I will find the time needed to complete it in the next weeks...

How to manage extremely complex 3D models in FSX

One of the issues I had devoping the F-35 was the extreme complexity of the model in terms of polycount - which led to several issues while compiling the model.
The problem I had was related to some of the "undocumented" FSX limitations. It was advertised that FSX models had no restrictions in terms of poly count, making it possible to create extremely complex models - far beyond FS2004 limits.... And this is true, with a catch.

There is still a 64K buffer limit for the draw calls - which in FSX are "grouped" by material. That is, you cannot have a unlimited number of vertices/polygons using EXACTLY the same material - as the polys of every part (even if disconnected) using the same material concur in the same draw calls buffer: this may result in:

• FSX exporter fails to compile
• Mdl is compiled but some parts are not showing correctly in FSX (either do not show at all, or they appear black or they cast shadows and don't show at all... I've seen every kind of weirdness)

SOLUTION:

• Create several slightly different copies of the material in gmax (e.g. Engine_material_1, Engine_material_2, Etc. which may differ just by 1 point of specular power in the basic material proprieties so they will look the same in FSX)
• Assign Engine_material_1 to some of the engine parts, Engine_material_2 to others, etc. so that each engine part goes into a different buffer
• Compile and be happy

This is the magic "trick" that allows extremely complex models in FSX.
ONE CAVEAT: if this is your case, it is likely you have exceeded the visual complexity reccomended by Microsoft. That means you may have users that will complain about the frame rates when compare your model to default ones...

To be honest this was not the first time I've encountered this problem - but I saw that this trick was unknown to some designers and I wanted to share the knowledge. By the way, I'm told that similar issues (and solutions) happen in FS9.

As for the F-35... in Italy we say "appetite comes with eating", meaning that once you started making one thing it may be difficult to stop. In this case, I started a minor rework of the MFD to add some functionality...and it turned into a major remake (which was also helpful to reduce the number of textures). As of today, HSI,MAP,ENGine,FUEL,FCS sub-screens are working and 99% complete... The other functions (COM,ICAWS and WEApon subscreens) are much easier to make - the problem is that I do not have much time to work in
I promise I will post some images tonight.

First flight of the fifth real F-35

The fifth F-35 prototype BF-03, landing after its first flight.

While I am struggling to find the time to complete and pack the Beta version of the virtual Lightning II, in the real world the fifth F-35 had its first flight. It is the BF-3 (that is the third STOVL prototype), and as you can see from the picture, it is completely painted in dark grey - which I assume it will be the standard livery for all the prototypes.

So, since the AA-1 has been retired, now there are four F-35s flying: AF-1 (CTOL), BF-1, BF-2 and BF-3. BF-1 and BF-2 are currently in Patuxent River and are undergoing a series of test flights that will culminate in the first actual STOVL flights - see http://www.jsf.mil/ for some cool hi-res pictures and additional details (including videos of the first lift-fan in-flight engagements).

As for the FSX projects... well, as I said I am struggling to find the time to work on it.
For those who are curious, the major differences from the beta will be:

• an updated visual model with more detailed 3d geometry (especially in the landing gear and refuel receptacle aeras) and more detailed textures - with slightly different coloring.
• a better flight model - with special thanks to Roberto Leonardo who provided some substantial tweaks to the .air file. The plane has now a more realistic turn performance, and a more "neutral" behaviour, in attempt to emulate the effects of an advanced FCC/FCS system.
• more VC functionality: it is now possible to change the functions of the four areas of the MFD by picking from the menus on the bottom. At present, HSI (with map mode), RADAR/MAP (with terrain mode), FCS modes are working (but do not expect anything too fancy - I've extensively reused FSX code for those) - ENGine, (mock) WEaPon, COMmunication, ICWS and FUEL modes are planned. SWAP and MENU button should be functional, too.

The MFD functionality is the thing that needs more work... may be 10-12 hours. Hopefully I will complete it in the next weekend.

Last I need to apologize again to anyone who has sent me an email in the past few days - my email is working but I did not find the time to reply, even to messages that are quite important for the project.

First flight of the Sukhoi T-50

Sukhoi T-50 first flight

A very interesting plane has made its first flight a couple of days ago - the Sukhoi T-50, that is the first Russian stealth fighter. Looks like a YF-23/Su-27 hybrid to me...and it also makes some of the Ace Combat 6 aircrafts look a little more lifelike... Here is a video of the first flight:

http://news.bbc.co.uk/1/hi/world/europe/8487026.stm

As for the Flight Simulator X F-35 project is proceeding in the right direction - and I'm confident that the Beta will be noticeably better than the Alpha in almost every respect. Hopefully it will be ready in a week or so.

F-35 Closing the alpha test

As the current build of the F-35 is now significantly different from the Alpha build, I am closing the Alpha test stage - I would like to thank all the testers for their detailed and competent feedback.
For now, most of the changes and improvements I've implemented were on the external and the flight model, while the VC still needs more functionality.

I will keep the Alpha WIP updated for a while, as I'll be going though all the list, and will post some updated screenshots soon.

Also, I'm experiencing some problems with my home email - my apologies for any delay in replying to your messages - rest assured that I will read all the messages and reply asap.

F-35 Alpha test Work-in-progress post

Below is a list of issues either known or found in the Alpha build as released to testers yesterday night. This list includes only the "accepted" issues - i.e. things that I acknowledge as actual defects (if compared towards the scope of the project). I will keep this list updated, as reference for me, for the testers and also for anyone interested in the project progress.

Note to testers: no need to rush - I won't have much time until the next weekend. While evaluating the flight model, please keep in mind the fact that the aircraft is loaded with two JDAMs.

UPDATED 23-01-2010

External model

1) Nozzle animation incorrect.
Action: redo animation sequence. Evaluate link to nozzle animation variable of FSX:Acceleration (SP2 compatibility?) or link to rpm for smoother animation - DONE in model build 43
Status:closed - solution approved for Beta - animation sequence redone. Still linked to throttle but closer to the actual behaviour.

2) Jaggies nearby the engine intake aera. Visible on close inspection only, partially due to geometry/smoothing, partially due to self-shadowing algorithm.
Action: evaluate mitigation by local application of Meshsmooth command. It may be impossible to fix completely - but will not be noticeable by most users.
NOTE: Upper to lower side discontinuity verified correct. Minor issue spotted with intake bulge curvature. Inspection highighted UVW misplacement in the engine intake area
Status:open - high priority

3) Excessive gap between engine nozzle and fuselage.
Action: check against photos and eventually modify the mesh.
Status:CLOSED - fixed on model buidl 46

4) Afterburner effect/1: effect poking through A/C fuselage. NOTE: FSX effects positioning an visibility is somewhat dependent on graphic card model and setting. Having the card set in "performance" mode makes things worse. E.g.not perceiveable on my system.
Action: modify .fx file (shrink them a little - check nominal position)
Status: open

5) Afterburner effect/2: flame should be much longer in stage 3. NOTE: a/b flame is confined into the engine nozzle on purpose for F-35B preparation. Also, my experience with "big" flames is not really positive (different users had different results).
Action: evaluate modification in .fx file. Stage 1 effect seems correct if compared to F-35 a/b videos.
Status: open

6) Wheel/tires animation incorrect. Status: CLOSED (Fixed dynamic modle for tires, diameters were wrong)

7) Navigation lights missing. Note: they were left out as all the F-35AA-1 pics I have are showing only anticollision lights. Status: CLOSED (Nav lights placed into the lights subassembly)

8) Covers for auxiliary air intakes missing when using SHIFT+E+4 command. Note: never seen such covers in any picture. Status: CLOSED (Auxiliary inlet cover modeled - but no ribbons as I'm saving polys for the weapons ).

9) Irregular bumps in the external model. Action: modify the extenal model. Sratus DONE: (model build 44) Auxiliary air intake untouched, other bumps geometry modified and new textures.

10) Poor detail in the refuel receptacle. Action: While the comment is correct, I do not have pictures clear enough to make a porper model - Edit: will model a stardard receptacle based on similar devices. Status: CLOSED. Refuel receptacle modeled in build 46

11) Poor detail in the nose landing gear. Action: Increase detail in the 3d model. Status: CLOSED - Mitigated issues with additional gear detail, previously missing.

12) Modeling mistakes in the main gear. Action: evaluate complete redo of the kinematism. Status: Closed on model build 45 - Redone most parts of the main gear and applied new textures.

13) AIM-120 not attached to hardpoints. Action: will model LAU-147 (although not actually mounted in AA-1). Status: CLOSED modeled hardpoints for AA-1 will model LAU-147 for operative model

14) Nose gear door detail/accuracy not good enough. Action: impossible to modify the shape, but will redo the hinges and add the actuator. NOTE: Applies only to AA-1 model - other models have a different door (2 parts). Status: Closed (model build 45 - Redesigned hinge and added actuator and new texture)

15) Request to model the lights in more detail. Action: modify the model. Note: initial evaluation shows that boolean operation is requested: such operation will inhibit model roll-back. Status: CLOSED (No additional modeling, but better texture)

Miscellaneous other actions (not requested by testers):

- Resize main gear wheels / tires - DONE

- Add detail to the main fuselage texture diffuse/spec/bump - DONE

- Evaluate changes in texture brightness /contrast - DONE, also miscellaneous enhancements to AA-1 texture coloring. Note: experiments with primer-only AF-1 texture looking good.

- Fix mistake in texture UVW in the inner side

- Add separate moving part for weapon door hinge - visible on real plane on closer inspection, not modeled DONE

- A/c is sitting rather low on the main gear. Changes to the animation sequence and contact points needed. FIXED

Virtual cockpit

1) Virtual cockpit frame rate low / excessive number of polygons.
Action: optimize virtual cockpit model mainly by removing some of the parts of the external model attached for track IR users (eg. lower surfaces fuselage, flaperons, tails). Evaluate reduction of invisble polys/faces. NOTE: Only one tester has highlighted this issue. Performance seems on par with similar products for the others.
Status: open

2) Temporary HUD useability (keeping this open in case the new HUD/HMD is not available on time)
- Proposal to reduce the size of the 3D part
- Enlarge the G meter text window
- Enlarge various text windows in 2D panel

CLOSED / NEW HUD IMPLEMENTED AND AUTHORIZED

3) Minor texturing UWV misplacement on cockpit floor.
Action: fix mapping in .mdl file. DONE in VC build 19
Status: CLOSED

4) VC night lighting too bright.
Action: dim the brightness in .fx files.
Status: CLOSED - modified .fx file

5) Incorrect tooltip showing "parking brake" in the battery area.
Action: check .XML embedded in the .mdl. DONE in VC model build 19
Status: CLOSED

6) Miscellaneous autopilot interface:
- Autopilot master hotspot not working. NOTE: A/P master will be part of the FCS panel
- Autothrottle miscellaneous issues. NOTE: At first check it .XML appears correct. I had similar issues in the tomcat.
- Autopilot max bank activation. NOTE: Presence of this command is a mistake and will be removed.
Action: check associated .XML
Status: open

7) Engine needles behaviour not correct
Action: check associated .XML
Status: CLOSED. COMPLETELY NEW GAUGE

8) Visual hole aboce the pedals (polygons missing); Action: modify the Vc model (add a cap) Status: CLOSED (VC model build 20)

9) "No Hold" texture stretched above ejection seat; Action: modify the Vc model / texture; Status: CLOSED (VC build 23)

10) "patches" on the side of the Vc glass are unconnected to the canopy; Action: modify the Vc model; Status: Unclear how the thing should look like. CLOSED for now.

11) Explosivc cord not connected to glass; Action: pending evaluation - this was intentional to prevent clipping that happened during initial tests; Status: Closed with no action - Current geometry prevents clipping. Leave as is.

12) Stick movement excessive if compared to real F-35 stick. Action: modify animation sequence. Status: closed (VC model build 20 movement reduced, still not as little as the real one but provides a "visual feedback" that enhances the experience IHMO).

NOTE: Track IR testing generally good. No major issues, apart from the "usual" seat clipping and minor flaws in extreme conditions.


Flight model

1) Excessive top speed. Top speed in excess of 2.05 Mach. Real plane rated 1.6 to 1.8 (varying according to sources).
Action: change the wave drag table in the .air file - DONE
Status: CLOSED - approved for Beta. New wave drag / Mach table makes it extremely difficult to exceed Mach 1.69

2) Weak brakes. Brakes cannot hold the plane still even at relatively low RPMs.
Action:modify brake effectiveness either in the .air or .cfg file - DONE
Status: closed - promoted to beta. The brakes are now strong enough to keep the plane still up to almost full military power. However, brakes seem excessively strong when stopping the plane after landing.

3) A/c prone to yaw instability during takeoff run. NOTE:Verified only with crosswind.
Action: root cause unknown. Check for asymmetric loads. Possibly increase yaw stability/MOI or adjust scalars.
Status: Modified values in the air file parameter. Symmetric load checked and correct. Still happening with significant crosswind (15 kts or above). Should be manageable by most pilots. Awaiting flight test to close. CLOSED. LEFT AS IS FOR BETA TESTING

4) Micro-oscillations while on ground. Probably due to contact points instability.
Action:modify contact points parameters in the .cfg file. NOTE: was not present in earlier build (with incorrect auxiliary contact points) DONE in latest aircraft.cfg
Status: CLOSED

5) Pitch changes depending on throttle setting. FCC/FCS should compensate such effects in the real plane. Effect seems related to center-of-lft vs. center-of-weight misalignment, as proper .air files parameter seem correct.
Action: Check .air and modify a/c balance in order to minimize such effect. NOTE: for FCC/FCS emulation, it may desireable to set to 0 all the secondary effects of aerodynamic surfaces.
UPDATE: All fore/aft loads artificially balanced towards the aerodyamic center. Load is now balanced versus pitch. This is not theoretically correct, but makes up for the FCC/FCS absence. Issue seem mitigated to the point of being acceptable for the vast majority of the users. UPDATE: I forgot to to balance the engine pitch momentum - my bad, thanks Robby.

Status closed: Behaviour balanced in most situations.

6) Pitch changes when activating virtual speedbrake. FCC/FCS should compensate such effects. See 5) - it is probably the same issue.
Action: See 5
Status: Closed. Not completely solved but definitely acceptable.

7) Low roll rate. User report low roll rate for a fighter. NOTE: it is unclear what the actual roll rate should be. Current roll rate seems realistic for a plane with 2 JDAMs and 2 slammers, but may be less agile than real F-16,
Action: Aileron action enhanced by 10% - but awaiting further evaluation and feedback.
Status: CLOSED on latest fligh model - enhanced ailerons effects and travel. As a good side effect, a/c is more maneuverable at low speeds.

8) Excessive loss of energy during high-G turns. Action: unclear what the target should be for this plane in the depicted configuration. Assuming 5 - 6 g sustainable turn. Will see what I can do. Status: CLOSED with thanks to Roberto Leonardo

9) High AoA dynamics causes excessively low stall speed (75kts). Action: TBD some users are happy with the high AoA dynamics, as in line with some claims by LM. Will evaluate minor changes. Status: open - unclear if it is better to leave it as is. CLOSED. LEFT AS IS FOR BETA TESTING

10) Check landing attitude AoA (approach at 140kts?). Action: TBD - The only information I have is about X-35 whose appoaches were conducted at rather high speeds (155/165 kts). NOTE: Most users report the landing behaviour is good. Status: open - unclear if any action is needed. CLOSED. LEFT AS IS FOR BETA TESTING

11) Full flap deployment happens at low speed. Action: TBD - flap is controlled by FSX via the maneuvering flap option. Check if it possible to modify the speeds, otherwise no action. Status: open. CLOSED. LEFT AS IS FOR BETA TESTING

12) Virtual speedbrakes not much effective. Action: easy fix to the .air file. Status: CLOSED - Boosted speedbrakes effect

APPENDIX A: LIST OF MISSING (BUT PLANNED) FEATURES IN THE VC

- ICAWS (currently not working at all)
- FCS window to include touch screen functions for flaps/brakes/trim/autopilot master switch (note: this may not be realistic as those are typical HOTAS functions...still may have some use for FSX)
- FCS window will show more information
- Context sensitive weapon window pop-up (with no actual functionality)
- Touch screen radio window within the MFD
- Context sensitive HUD backup window within the MFD
- Fuel receptacle/weapon bay opening activation via touchscreen (currently implemented but not working due to an unidentfied bug...)

APPENDIX B: LIST OF OTHER MISSING (BUT PLANNED) FEATURES

1) AF-1 vsual model:
- new two piece nose landing gear doors
- new APU exhaust location
- new probes
- jagged fuselage/nozzle interface
- weapon bay: undecided between real and mock JDAM
Livery: still undecided between official artwork or actual primer-only appearance

2) Production F-35 model - same as above but:

- Removal of the nose probe
- EOTS
Livery: Most probably USAF 58th FS "Mighty Gorillas", which I understand is the first confirmed unit to receive F-35s.

3) Generic F-35 model for repaint

APPENDIX C: LIST OF NICE-TO-HAVE FEATURES (NOT PLANNED)

1) F-35A Thunderbirds (according to promotional LM artwork).NOTE: would require a special flight/visual model (with no weapons)

2) F-35A with external loads

3) F-35B STOVL version. Would require a lot of work to modify the visual model. Also, it would have the "superflaps" flight model.I know it is pretty lame but STOVL dynamics is not natively implemented in FSX... FSUIPC.dll methods exist but I do not want the model to be dependant on external modules

4) F-35C Would require a lot of work to modify the visual model and extensive flight test for carrier trials.

5) Custom sounds - I know it would be nice...

Color key:
Green - issue solved, or mitigated to the point is acceptable or not perceived by most users
Yellow -issue open, and could be perceived as product defect by many users. Awaiting action or investigation. Or issue open, mitigated to the best of my knowledge but will still be perceived as defect by users. Or issue open but appears easy to fix.
Red - root cause not identified as of today. Or the problem is beyond my knowledge or impossible or difficult to solve.