Friday, November 2, 2018

F-35 LIGHTNING II UPDATE TO VERSION 3.53


While debugging the E-2/C-2 Package I have discovered a nasty bug in the TACAN system that affects also other planes… so I took the chance for a quick update to the F-35. Here are the details of the update:


CHANGE LOG
Version 3.53 - 02/11/2018
- Fixed major bug in NAV1/TACAN frequency conversion causing generating incorrect TACAN channels in some instances.
- Fixed bug preventing NAV1 frequency tuning once a TACAN channel has been entered
- Fixed graphic glitch in MFD TSD1 screen
- Fixed minor graphic glitch in BFI Baro setting window
- Updated Koninklijke Luchtmacht F-35A livery
- Added F-35C VFA-147 Argonauts USN livery
- Fixed wrong entry in F-35C configuration file

NOTE: THE UPDATE WILL RESET THE MFD TO "FULL FEATURE" MODE. IF YOU WANT TO USE THE SIMPLIFIED MFD YOU MUST RE-APPLY THE SIMPLIFIED MFD PATCH OVER THE UPDATES FILES.

NOTE: THIS UPDATE WILL WORK WITH ALL PREVIOUS VERSION STARTING FROM V3.50. WHICH MUST BE DOWNLOADED BY YOUR DISTRIBUTOR OF CHOICE.

The update can be dowloaded from the sidebar or by clicking HERE.


7 comments:

Ricnunes said...

Hi Dino,

First of all I want to thank you for another F-35 update.

Secondly I do want to report another issue that I found regarding your F-35 flight model:
- I noticed that your F-35 cannot attain maneuvers with a Angle-of-Attack (AoA) of more than 28 degrees. This concurs with the fact that I don't seem to be able to perform sharp turning maneuvers like the real aircraft can attain and have for example been observed during some airshows.
While the real F-35 have been tested up to 110 degrees AoA, the operational F-35 flight software limits the AoA to 50 degrees which by itself is almost the double of what your F-35 can currently attain with 28 degrees AoA. This can be read here:
https://www.f35.com/in-depth/detail/the-f-35s-high-angle-of-attack-explained

Resuming what I'm requesting here is that/if you expand your F-35 maximum AoA capability from the current 28 degrees to 50 degrees.

ScimmiaSpaziale said...

@RicNunes

Thing is as follows: you are perfectly right in saying that the F-35 has publicly demonstrated, during air shows and during flight test, manouverability far beyond the limits depicted in the simulator - and I am fully aware that the FCS limits the AoA for a number of reasons (the famous Pirep F-35 vs. F-16D has the FCS limited to about 30 degrees).
However, we could not find any official flight data on the topic - not to mention what the aicraft can attain in combat configuration.
For this reason the flight model has been tuned to mimic a typical 4th generation high-performance fighter (for which there is an abundance of data) such as an F-16 in combat configuration. This may be overly pessimistic, but we felt it was better than risking to have an irrealistically supermanouverable aircraft.
Anyway, we'll furtherly review the information currently available and see if there are safe changes that can be done.

Ricnunes said...

@ScimmiaSpaziale,

If you read carefully I posted a source above where it states that the F-35 FCS limits the AoA to 50 degrees. Here's again the source:

https://www.f35.com/in-depth/detail/the-f-35s-high-angle-of-attack-explained

Where is can be read:
"The F-35’s high AoA testing pushed the jet to the AoA limit of 50 degrees nose high and included beyond both positive and negative maximum command limits."

That's official LM webpage above.
And there's also this:
https://www.flightglobal.com/news/articles/reduced-f-35-performance-specifications-may-have-sig-381683/

Where one can read:
"Once engaged within visual range, given the F-35's limitations and relative strengths, turning should be minimized in favor of using the jet's Northrop Grumman AAQ-37 distributed aperture system of infrared cameras, helmet-mounted display and high off-boresight missiles to engage the enemy aircraft. If a turning fight is unavoidable, the F-35 has good instantaneous turn performance and good high angle of attack (50°AOA limit) performance comparable to a Boeing F/A-18 Hornet, which means a similar strategy could be adopted if one finds him or herself in such a situation."

So the 50 degree AoA limitation is for a combat configured aircraft and not exclusive to some airshow and/or test aircraft.

And that test flight (I repeat test flight) that you're mentioning about, the F-35 against the F-16D was exactly to test and expand the F-35 FCS rules which including the expansion of its AoA maneuvering and this even happened before Block 3F which expanded the F-35's FCS rules even further like for example allowing the F-35A variant to attain 9Gs.
Honestly I'm still puzzled why people still talk about this test. It was a simple test to prove that the F-35 could be expanded even further, something usual on fighter aircraft testing, nothing more. Anyway, this is past. This was a prototype (AF-2) and pre-Block 3F aircraft.

I hope that you don't get me wrong but I think it's a wrong assumption to use the F-16 or a "typical 4th gen fighter aircraft" as a basis for modeling the AoA limitation since the F-35 was build to achieve maneuvers with a much higher AoA compared to the F-16 (50 degrees for the F-35 against around 25 degrees for the F-16 if my memory doesn't fail me) and even the F/A-18 Hornet (which is a also a 4th gen fighter aircraft) can attain similar AoA maneuvers as the F-35.
Actually it's often quoted, even by the manufacturer (LM) that the F-35 is in terms of agility the combination of the F-16's energy maneuvering with the High AoA maneuvering of the F/A-18.
So modeling the F-35 AoA maneuvering after the F-16 would be unrealistic. It would be far more realistic to model it after the F/A-18 for that matter.

If you think that the evidence above is not enough, I'll gladly try to find you some more info if you want? Please feel free to ask if that's the case.

ScimmiaSpaziale said...

Hi Ric

rest assured that I've read the article you sent carefully - also, I constantly peek over all the available sources (including all the post at f-16.net) and I had a good look at all the F-35 demos.

First thing: actually, the AoA limit in the simulator is something in the area of 35 degrees - the stall warning is shown before the stall actually occurs.

That being said, the problem is that we (or LM or the flight test crew) should define what they intend with the AoA "limit" - in reality you can pull very hard on the stick if the FCS allows you to do so, and achieve 100-110 degrees (i.e. Pugachev's Cobra and similar maneuvers)...but in those conditions the airflow has detached from the aerodynamic surfaces and actually the plane is flying on its inertia and engine power - so aerodynamically it is a "stall".

I believe (and I may be wrong) that the AoA limit of "50°" indicates that the FCS can provide some controllability of the Aircraft at 50° AoA and does not act to reduce the AoA below that threshold. This does not mean that the F-35 can fly and manouver at 50° in a sustained way.
The famous routine at the Paris airshow demostrated yaw contollability way above 50° AoA, but the plane was effectively "falling" in a controlled way (which is no small feat!) but does not mean that the Aircraft can sustain, for example, a 180° bank turn at 50° AoA.

As far as I can see the FCS can do wonders in post-stall controllability, but I have yet to see any convincing evidence that it can sustain turns at 50° AoA… that would be an awesome feat of engineering and would outperform any other fighter (including the F-22 and the Su-27).

Then, if you say that the real world Aircraft has a much better controllability at high AoA during "airshow" maneuvers than the simulated one...well, I cannot but agree!



ScimmiaSpaziale said...

In addition, I have furtherly discussed the question and the article with Roy (as I did in the past months) - his reply was as follows:

"As regards AOA, The article did not say how 50 was reached. The assumption might and clearly was that you could pull a turn at 50 AOA. Fact is you can get 50 by yanking it back into the stall, but this side of Harry Potter, there is no way airflow can stay attached at that AOA so it is not a steady pull situation but a demonstration of control and not loss of control at that AOA. The peak CL is actually at 30 in the model, at 35 it is only slightly reduced, at 56 it is still 80%. The sim will put on the stall light, but it is not really stalled and most of the lift is effectively airbrake."

Again, we believe that at those AoA the F-35 (and any other fighter aicraft) can demonstrate controllability - but that is not "sustained" flight. And again, the F-35 showed to its critics that it can do as well as any reasonable threat it may face.

ScimmiaSpaziale said...

...for the record, the discussion above made me want to do a quick flight on the F-35.
I have changed the HMD so that it shows AoA up to 50° (as opposed to 30° in the current release). Roy's statement are correct (and I had no doubt about that!) - while the stall warning starts at about 30°, you can maneuver way above that and still keep a good control of the aircraft.

I will make this change to the HMD available at the earliest occasion.

Ricnunes said...

@ScimmiaSpaziale,

The only reason why a F-35 cannot maintain/sustain 50° AoA (or any other aircraft that can reach those high Alphas like for example the Hornet) is because like you correctly said, High Alphas act like an "airbrake" and if sustained the aircraft will eventually lose its airspeed (quite quickly) and eventually stall - So again, you're right here.
However this has nothing to do with the controllability in which yes, I have no doubts that the F-35 is fully controllable during 50° AoA (if it still has energy left that is) or else the F-35 FCS would never allow the aircraft to reach such High Alphas. Actually like mentioned earlier, the F-35 is controllable at higher Alphas than 50° however this limit is likely a safety threshold.

When you said:
"but I have yet to see any convincing evidence that it can sustain turns at 50° AoA… that would be an awesome feat of engineering and would outperform any other fighter (including the F-22 and the Su-27)"

No, I never said or intended to say that the F-35 should be able to sustain maneuvers at 50° AoA (as you correctly said the aircraft will lose energy quickly by doing that) - By the way, sorry if I gave you that idea - but yes, the F-35 is indeed an "awesome feat of engineering" in which it can perform closely and perform similar maneuvers as even aircraft with TVC-engines, namely such or as close as those performed by the F-22 (see video below).
I have absolutely no doubts that the F-35 can outperform the Su-27.

Being able to attain High Alphas is indeed a vital feature that allow the F-35 to attain its "super-maneuverability" which comes from engineering features such as body lift, carefully placed twin tails and LERX which allows the generation of vortex flow "aimed" at the tails so that the tails can continue to give the aircraft's controllability/stability which is something that for example single tail aircraft cannot attain in such circumstances and so on... Together with all this, we have an aircraft with a very powerful engine (the most powerful engine ever fitted on a fighter aircraft) which gives it an impressive subsonic acceleration (specially the F-35A variant which with full internal weapons basically has the same subsonic acceleration as a clean F-16) and this is where I also feel that there's something off with your F-35:

- While I'm glad that you were able to change the F-35 HMD to show that it can reach a 50° AOA but when performing such sharp turns to one side (left side for example) and after which the I decide to compensate by turning to the other side (to the right side for example) and this after the sharp turn then the aircraft violently banks to the side that I was turning last but way more and "violently so" than what I want/wish and which seems to show that the aircraft is no longer controllable and worse even, it pitches nose down and loses lots of altitude afterwards.

Or resuming, unfortunately you cannot perform this impressive maneuver with your F-35:
https://www.youtube.com/watch?v=6Kg-ztkPDok

Actually when performing such maneuver (similar to the ones of the video above) with your F-35, it basically acts totally different (again instead of being able to have full control after the turn it doesn't, after performing the turn instead of being able to gain altitude it actually loses lots of altitude and of course it has a very hard time accelerating after the turn).

I hope that this time (with the help of the video above) I have explained better what I'm mentioning here? But in case not, please feel free to say.

And by the way, I want to thank you the attention that you're giving me about the subject!