Will this flight behavior be relevant to our F-16 ?

[Demongornot]

I have seen this video a long long time ago, this is an F-16 with asymmetric missile payload in certain conditions.

I don't know if the F-16 we will have in DCS have a software patch for this behavior or not, and if not, would the flight model be able to reproduce such behavior ?

 

Edited August 5, 2019 by Demongornot
Apparently the video integration is disabled on this video, I reverted to plain link.

[Cupra]

If DCS make a real and working flight model with all the wind effects and so on it will.. if not, you get a jet flying on rails through the sky…

 

You can test it later.. all the flight limits and other stuff are available to the public… Make your test flight and decide then.

[Demongornot]

Wait, did I posted it on Wishlist or was it moved there ?

 

If DCS make a real and working flight model with all the wind effects and so on it will.. if not, you get a jet flying on rails through the sky…

 

You can test it later.. all the flight limits and other stuff are available to the public… Make your test flight and decide then.

 

Well, we know for sure the F-16 will have realistic flight model, no new aircraft since LOMAC got released with simplified flight model (flying on rail as you said it), since LockOn: Flaming Cliffs introduced the SU-25T with advanced flight model, no new aircraft had it after (except sub variants of existing LOMAC aircraft I think), but this doesn't mean that our F-16C Blk 50 won't have a flight computer system to prevent this or that the flight model will be actually accurate enough to model it, which is why I asking.

 

And well, if I am asking now, this is because I would like to know now? And also to point out this particular effect on the Viper.

[mvsgas]

I have seen this video a long long time ago, this is an F-16 with asymmetric missile payload in certain conditions.

I don't know if the F-16 we will have in DCS have a software patch for this behavior or not, and if not, would the flight model be able to reproduce such behavior ?

 

 

There is a a lot of things that video does not tell us or ED. For example; which Flight control computer it had? Which software version it had? What are the differences between different flight control computers? What are the differences between the computer software? Being a test aircraft, did it used the operational limits or where they modified for the testing? Did they change the center of gravity for the test? What was the fuel level? At what speed does this happen? ( high transonic, above 35k feet is not very precise numbers). In the video it looks like a center line tank and a pod on the right cheek. What pod was on the right cheek? Which version of the AIM-120 was it carrying? Was that the main cause of the departure? I'm not sure of the tail number, it looks like 87-0352 a block 40, but being a test aircraft, it could have many or no modification.

 

In short, whether ED decides to model this or not would be up to them and it would be impossible for any of us to determine the validity of it with the information available to us.

 

Edit:

To clarify, when I say: "which Flight Control Computer" I do not mean the differences between an A model Flight Control Computer (FLCC) and a Block 50 Digital Flight Control Computer (DFLCC). I mean there are different DFLCC installed with different software at different times on a specific block. For example Time Compliance Technical Order (TCTO) 1F-16-2594 change the DFLCC from part number 3757528-1 to part number 16VC0126-100. I could not tell you the differences and I doubt anyone else could.

Edited August 6, 2019 by mvsgas

[Demongornot]

There is a a lot of things that video does not tell us or ED. For example; which Flight control computer it had? Which software version it had? What are the differences between different flight control computers? What are the differences between the computer software? Being a test aircraft, did it used the operational limits or where they modified for the testing? Did they change the center of gravity for the test? What was the fuel level? At what speed does this happen? ( high transonic, above 35k feet is not very precise numbers). In the video it looks like a center line tank and a pod on the right cheek. What pod was on the right cheek? Which version of the AIM-120 was it carrying? Was that the main cause of the departure? I'm not sure of the tail number, it looks like 87-0352 a block 40, but being a test aircraft, it could have many or no modification.

 

In short, whether ED decides to model this or not would be up to them and it would be impossible for any of us to determine the validity of it with the information available to us.

 

Edit:

To clarify, when I say: "which Flight Control Computer" I do not mean the differences between an A model Flight Control Computer (FLCC) and a Block 50 Digital Flight Control Computer (DFLCC). I mean there are different DFLCC installed with different software at different times on a specific block. For example Time Compliance Technical Order (TCTO) 1F-16-2594 change the DFLCC from part number 3757528-1 to part number 16VC0126-100. I could not tell you the differences and I doubt anyone else could.

 

Well I don't know how they code their flight model, but I really don't think they code specific behavior, but rather make a realistic aerodynamic representation of the aircraft which end-up "automatically" reproducing those behaviors because of the coded data of lift, drag, stall angle, rudder masked from airflow at certain angle loosing efficiency etc

And in this case my question is really, will the flight model be accurate enough to reproduce such characteristics.

Any behaviors caused by weight change over the normal should be actually reproducible in the flight sim if we put similar weight if the flight model is advanced enough.

Same for speed and altitude, the flight model should reproduce it by itself if we do the same.

I really doubt that the flight model, for the SU-27 or SU-33 include specific line of code for the Pugachev Cobra for instance to tell at which altitude, speed, weight etc to perform it, but rather it being a result of the simulated aerodynamic property of the aircraft.

And the aircraft in the video is probably 100% identical aerodynamic wise to the regular one.

 

Well, true they can't know what is the flight computer used in this video or if it was modified or not, but I guess if they are gonna model the flight computer, they'll know what it does or doesn't contain, which include potential fix for this out of control departure.

[mvsgas]

Ok, but is the departure an aerodynamic result or is it because of the load out? Is the departure due to the AOA/G limiter being modified or operational? In the video, the pilot said the departure was expected, but why was it expected? Was it expected because they had all the fuel on the right wing and none on the left wing? Was the departure because Fuel tank F1 and F2 empty while A1 was full? If we don't have all the information on how it happen and what cause it, how can we tell if ED modeled correctly or not? For all we know this only happens with a center line tank and a sniper pod at a specific fuel load with no AOA/G limiter.

Edited August 6, 2019 by mvsgas

[mvsgas]

Lets say the module is release. The first thing we do is load up a centerline tank, 3 -120B and a pod on the right cheek. You try the same maneuver at 36k feet at mach .95 and nothing happens. You post the flight model is wrong because it does not behave like the video. ED post that this only happens on block 40. Can you honestly say otherwise with the information we have? I can't. If you can, would you please tell me how? I am not being sarcastic nor trying to be funny. I am honestly curious on how can any of us determine if it will be accurate or not by watching this video.

Edited August 6, 2019 by mvsgas
spelling

[Demongornot]

This is both because of the aerodynamic and loadout, both are always linked together, weight distribution determine what goes in front and aerodynamic what move, how it move and what goes on the back (well this is an over simplification of course).

But the F-16 in this video is probably 100% the same as the regular on the aerodynamic aspect, only the payload itself make it different, and I think they simply put regular pod, tanks and AMRAAM rather than modified ones, so the real unknown is more about the flight computer, but if the one that we will have in DCS have a flight computer patch for that, they'll probably know about it as they probably have the relevant documentation.

Note that I haven't done any research at this point, I just pointed out an old video I remembered.

 

So now if we do researches, we can start to find answers, here is one :

Here about the causes : https://www.flightglobal.com/news/articles/f-16-spin-recovery-technique-invented-24842/

Asymmetric loadout coupled with inlet mounted pod is responsible, also we can see that this is a really old article (08 OCTOBER, 1997)

 

Note that I posted this link because I think it is rule 1.16 safe, but there is many other sources, including an official PDF doc but it is a download rather than an online consultation, search for :

"SAFETY INVESTIGATION REPORT HELLENIC AIR FORCE F-16D BLK 50 S/N 93-1084 341SQ/111CW ALBACETE AFB (ESP), ALBACETE 26 JANUARY 2015"

 

To quote the PDF :

When ARI activates after takeoff, roll trim for asymmetric stores causes a rudder

input that can cause aircraft yaw away from the wing with the asymmetric store (heavy

wing). This yaw is easily controllable through pilot rudder inputs

 

Asymmetry loading. A left-wing heavy asymmetric F-16 is more susceptible to yaw

departure, relative to a clean C-model.

 

So I think this is a F-16 + asymmetric loadout related thing, no need to modify anything like putting fuel in one wing only or something else, also they used AMRAAM in the video, not the heaviest weapon, they could have use bombs instead, I mean the 120 is twice as heavy as the Sidewinder, but the Maverick is twice as heavy as the 120. HARM is heavier than the Mav, Jsow is even heavier, and the largest bombs the F-16 carry are even more, so why only 2 vs 1 AMRAAM and put effort into putting fuel in one tank only or changing the center of gravity ?

I mean the goal was to research how this can happen in combat situation.

[mvsgas]

Ok, so we ignore the video that does not tell us or ED anything and we sum it all up with actual number.

Will the DCS F-16 be more likely to have a yaw departure under the following conditions?:

- Above 25000 feet

- Between .80 and .95 mach

- Rapid onset of AOA after a roll

- While flying close to the AOA/G limiters

 

What will be the limiter for the DCS USAF block 50 circa 2007?

- Looking around we find the USAF F-16 block 40/42 circa 2009 Cat 1 pitch limiter is 26°, Greek block 50 circa 2003 is 25° and circa 2015 is 25.8°. I do not know the limiter for a circa 2007 USAF block 50. There are many more factors to the limiters. (*)

- Cat 3 limiter for the USAF block 40/42 circa 2009 and a Greek 50/52 circa 2003 is 16°-18°, 2015 Greek block 50 is 16°-20°

 

What factor could increase the chances of yaw departures?

- Center line store (center line tank with pylons on station 3 and 7 being worst case scenario)

- 370 wing tanks

- heavier left wing

- asymmetric loaded inlet mounted pod

- In Cat 1, more susceptible loading is a lateral asymmetry load greater than 300 lbs on station 1,2 or 3 with center line tank and asymmetric inlet mounter pod.

- In Cat 3, and asymmetry load greater than 1500lbs on station 3 or equivalent

 

* Talking about DFLCC:

We can see the pitch limiter is different on different block at different times. Some of the questions are:

- What else on the limiters and other functions may change depending on flight control computer and its software?

-- For example USAF block 40/42 circa 2009 cat 1 roll limiter is not affected by rudder input while a Greek 2003 block 50 is.

- What are all the ways to defeat the limiter?

- How to avoid defeating the limiters? etc.

Edited August 7, 2019 by mvsgas
spelling

[Demongornot]

Great summary, also maybe rolling the aircraft "help" because roll always create a little yaw movement and the engine centrifugal force is also a factor, so this may happen only at certain regimes.

[mvsgas]

Great summary, also maybe rolling the aircraft "help" because roll always create a little yaw movement and the engine centrifugal force is also a factor, so this may happen only at certain regimes.

 

Rolling just before pulling is attacking the limiter. Basically giving the computer to many variable to solve. The rolling does induce yaw, but the main thing is to attack the DFLCC limiters in attempt to defeat them. The most critical maneuvers are maximum command rolls coupled with either maximum aft stick or exceeding the maximum bank angle change limits.

 

With all this information, you can see in the video they did everything they could to make that aircraft depart in yaw.

[mvsgas]

A model, not sure if from Norway or the Netherlands.

Not sure why but this video play bad in my PC, it just keeps stopping. I can play 4k videos without issue.

[Deano87]

Yup... it didn’t like that.

 

:D

[Bouli306]

A model, not sure if from Norway or the Netherlands.

Not sure why but this video play bad in my PC, it just keeps stopping. I can play 4k videos without issue.

 

 

 

First of all...how do we know he is out of control? no speed, no AOA readout....

 

 

Because the manoeuvre was a little violent? Normally when a guy goes of control he goes home...because it might be a problem with the FLCS.

So if the AOA and speed are not known you do not know if he went out of control.

[mvsgas]

First of all...how do we know he is out of control? no speed, no AOA readout....

 

 

Because the manoeuvre was a little violent? Normally when a guy goes of control he goes home...because it might be a problem with the FLCS.

So if the AOA and speed are not known you do not know if he went out of control.

 

Where did I posted it was out of control or that I know anything about the aircraft parameters? I just posted a interesting video on a related thread. You can contact the author if you need further info.

 

The only two thing I mention: It looks like a A model ( looking at other video on the channel it appears to be either from Norway or the Netherlands.)

 

And I mention having problems watching the video. All other information is presume by you not me.

 

You are correct we have no info on the aircraft, no configuration, don't know the intention of the pilot nor the reason he was maneuvering like he did.

[Bouli306]

Where did I posted it was out of control or that I know anything about the aircraft parameters? I just posted a interesting video on a related thread. You can contact the author if you need further info.

 

The only two thing I mention: It looks like a A model ( looking at other video on the channel it appears to be either from Norway or the Netherlands.)

 

And I mention having problems watching the video. All other information is presume by you not me.

 

You are correct we have no info on the aircraft, no configuration, don't know the intention of the pilot nor the reason he was maneuvering like he did.

 

True statement. I was focused in the title of the video.