Will the FBW with C* law be implemented ?

[cmbaviator]

Hi guys,

 

i was wondering if the F16 will have FBW and more specifically the C* law.

 

I think the F16 was the first aircraft to have the FBW C* law than would be used and modified by Airbus for their A320 and above and later on byt BOEING but with the C*U law.

 

 

From what i understand, is that the C* law is base on pitch rate demand at low speed ang G demand on high speed. Besides it is fligh path stable, so for instance, if you fly at 200 kt IAS level and accelerate to 500 kt IAS, you should remain level, maintain path in turns..., in a conventional aircraft ( Direct law) you would pitch up or down if you decelerate.

 

http://www.icas.org/ICAS_ARCHIVE/ICAS2012/PAPERS/605.PDF

[Madbrood]

I think the F16 was the first aircraft to have the FBW C* law

 

I would imagine that (given the amount of declassified data available on the F-16) if the real jet has it, ours will too.

[GGTharos]

Does the DCS f18 not do this already?

[cmbaviator]

I would imagine that (given the amount of declassified data available on the F-16) if the real jet has it, ours will too.

 

where can we find such data ?

[cmbaviator]

Does the DCS f18 not do this already?

 

good question, can find something that states that F18 has FBW

[Airhunter]

Does the DCS f18 not do this already?

 

Veery poorly. It wobbles all over the place and does not maintain pitch very well (usually deviates by itself from the commanded pitch).

[cmbaviator]

Veery poorly. It wobbles all over the place and does not maintain pitch very well (usually deviates by itself from the commanded pitch).

 

depends, fbw wit autotrimming, will tend to maintain flight path and not pitch, so lets say you flight level and accelerate, the noseshould go down

[probad]

my burning question is why you think it wouldnt be replicated???

frankly to even put out this question is insulting to the efforts of the developers

 

unless youre just having a poor time articulating a desire to learn more about f-16 claws at which there is already a discussion here

https://forums.eagle.ru/showthread.php?t=246228

Edited August 20, 2019 by probad

[cmbaviator]

my burning question is why you think it wouldnt be replicated???

 

frankly to even put out this question is insulting to the efforts of the developers

 

Well because it isn't even mention by them and it is a big deal:

 

Core systems of our F-16C include:

F-110-GE-129 turbofan engine

AN/APG-68(V)5 multi-mode radar

AN/ALR-56M Radar Warning Receiver

AN/ALQ-131/184 ECM pods

CCIP (Common Configuration Implementation Program) update

ALE-47 countermeasure system

 

This will be a massive project, so we will separate it into two phases: Phase 1 Early Access release and then Phase 2 Product Sustainment.

 

Phase 1 Early Access Release:

Color Multifunction Display (CMFD) symbology, Horizontal Situation Display (HSD) format, and Head-up Display (HUD) symbology

Digitally TACAN and Electronic Horizontal Situation Indicator (EHSI)

RWS, SAM, TWS and ACM A/A radar modes

BDU-33, BDU-50LD/HD, Mk-82LDGP, Mk-82AIR, Mk-84LDGP, CBU-87 CEM, and CBU-97 SFW unguided bombs

2.75” rockets LAU-68 and LAU-131

Joint Helmet Mounted Cueing System (JHMCS)

AIM-9L/M/P/X Sidewinder

AIM-120B/C AMRAAM

M61A1 20mm cannon

 

First skin will be the 55th FS at Shaw AFB.

 

Phase 2 Product Sustainment:

Multifunctional Information Distribution System (MIDS)

Link 16 Data Link

A/G radar modes

AGM-65D/G/H/K Maverick

AGM-88C HARM

AN/ASQ-213 HARM Targeting System (HTS)

AN/AAQ-28(V) LITENING targeting pod

GBU-10, GBU-12, GBU-24A/B laser-guided bombs

BRU-57/A Smart Rack

CBU-103 CEM and CBU-105 SFW Inertially Aided Munitions (IAM)

GBU-31/A and GBU-38/B JDAM

AGM-154A and AGM-154B JSOW

Integration of the JHMCS with the HARM Targeting System (HTS), Link 16, and AIFF

ALE-50 towed decoy

 

Can you see FBW features mentionned here ?

 

i'm only asking a question

[probad]

fbw is inherent to the aircraft design and is by necessity a core feature, doesnt need to be listed because it is simply assumed

 

the list there is IN ADDENDUM to general knowledge about the f-16

Edited August 20, 2019 by probad

[cmbaviator]

fbw is inherent to the aircraft design and is by necessity a core feature, doesnt need to be listed because it is simply assumed

 

the list there is IN ADDENDUM to general knowledge about the f-16

 

thanks

[mvsgas]

i was wondering if the F16 will have FBW and more specifically the C* law.

 

Will the DCS F-16 have FBW?

It should

 

Will the FBW use C* law?

If I understand correctly, C* law uses speeds (vertical speed, aircraft speed) to maintain flight path. Is my understanding correct?

 

I never heard of C* law so I am going by the pdf you provided.

[Airhunter]

Will the DCS F-16 have FBW?

It should

 

Will the FBW use C* law?

If I understand correctly, C* law uses speeds (vertical speed, aircraft speed) to maintain flight path. Is my understanding correct?

 

I never heard of C* law so I am going by the pdf you provided.

 

Basically in C* you command roll and pitch rates and give it a set flight path vector, which the aircraft maintains by itself. C*U for example is used in planes like the Boeing 777, where it feels a lot more conventional to the pilot. You trim for speed and roll rates are proportionate with flight columt deflection. You still get all the protections however.

[mvsgas]

Ok, thanks.

If that is the case, then no DCS F-16 should not use C* law since The RL F-16 does not AFAIK.

[cmbaviator]

Ok, thanks.

If that is the case, then no DCS F-16 should not use C* law since The RL F-16 does not AFAIK.

 

what law does it use then ?

[mvsgas]

what law does it use then ?

As I understand C* uses speed to maintain flight pad, is that how C* works?

 

Not sure what "Law" it uses, but during normal operation, Flight Control Computer (FLCC) provides relatively constant aircraft response for a given stick input, regardless of altitude or airspeed. This response varies slightly depending on configuration. In the event of a dual air data failure, the FLCS switches to standby (fixed) gains.

 

In cruise gains ( LG handle up), at low AOA, the pitch axis of the FLCS is a g command system. As AOA increases, the FLCS switches to a blended g and AOA system to provide a warning of high AOA/low airspeed. Roll rate limiting is available and maximum roll rate decreases as a function of low airspeed, high AOA, and horizontal tail position. The limits change depending on the FLCC and the software for it.

 

In takeoff and landing gains (LG handle down), the FLCS pitch axis operates as a pitch rate command system until 10 degrees AOA and a blended pitch rate and AOA command system above 10 degrees AOA. Roll rate limiting is available but is a fixed value independent of AOA, airspeed, or horizontal tail position.

 

In standby gains, control response is tailored for a fixed altitude (sea level, standard day) and airspeed (LG handle in UP, approximately 600 knots; LG handle in DN, approximately 230 knots). The FLCS warning light and FLCS FAULT caution light illuminate. When operating on standby gains, the LEF’s are at zero degrees with the LG handle in UP and the ALT FLAPS switch in NORM. The LEF’s deflect 15 degrees down with the LG handle in DN or the ALT FLAPS switch in EXTEND. The operation of the TEF’s is not affected in standby gains. A standby gains condition can be reset in flight, back to the first failure condition, by using the FLCS RESET switch. The original air data system failure is latched upon occurrence of the second failure and does not reset. If reset is successful, the FLCS warning light goes off. This last behavior is dependent of the specific FLCC and it software. Some may be reset some can't.

 

There is a lot more info, but I'm not sure if this answering your question or adding to confusion.

[cmbaviator]

As I understand C* uses speed to maintain flight pad, is that how C* works?

 

Not sure what "Law" it uses, but during normal operation, Flight Control Computer (FLCC) provides relatively constant aircraft response for a given stick input, regardless of altitude or airspeed. This response varies slightly depending on configuration. In the event of a dual air data failure, the FLCS switches to standby (fixed) gains.

 

In cruise gains ( LG handle up), at low AOA, the pitch axis of the FLCS is a g command system. As AOA increases, the FLCS switches to a blended g and AOA system to provide a warning of high AOA/low airspeed. Roll rate limiting is available and maximum roll rate decreases as a function of low airspeed, high AOA, and horizontal tail position. The limits change depending on the FLCC and the software for it.

 

In takeoff and landing gains (LG handle down), the FLCS pitch axis operates as a pitch rate command system until 10 degrees AOA and a blended pitch rate and AOA command system above 10 degrees AOA. Roll rate limiting is available but is a fixed value independent of AOA, airspeed, or horizontal tail position.

 

In standby gains, control response is tailored for a fixed altitude (sea level, standard day) and airspeed (LG handle in UP, approximately 600 knots; LG handle in DN, approximately 230 knots). The FLCS warning light and FLCS FAULT caution light illuminate. When operating on standby gains, the LEF’s are at zero degrees with the LG handle in UP and the ALT FLAPS switch in NORM. The LEF’s deflect 15 degrees down with the LG handle in DN or the ALT FLAPS switch in EXTEND. The operation of the TEF’s is not affected in standby gains. A standby gains condition can be reset in flight, back to the first failure condition, by using the FLCS RESET switch. The original air data system failure is latched upon occurrence of the second failure and does not reset. If reset is successful, the FLCS warning light goes off. This last behavior is dependent of the specific FLCC and it software. Some may be reset some can't.

 

There is a lot more info, but I'm not sure if this answering your question or adding to confusion.

 

thanks for the info but is there an autotrim feature that will try to make the aircraft flight path stable ?

[mvsgas]

Not that I know of. The aircraft will maintain G no matter the throttle position, but you can climb or descend in 1 g. Roll and Rudder would depend on configuration and asymmetric load out will not be corrected automatically by the FLCC.

 

I posted here about the trim

mvsgas said:

This information is for USAF block 40/42 circa 2009 Digital Flight Control System (DFLCS), block 32 and below uses a different system and this may or may not apply. Digital Flight Control Computer (DFLCC) has change several times and so has its software. This may not apply in different years and different countries.

Depends on landing gear (LG) handle position and in flight refueling (IFR) door position.

 

In cruise gains (LG up and IFR door close)

pitch trim inputs are g command signals identical in function to normal stick pitch commands.

 

With landing gains (or IFR door open)

It uses pitch rate command until 10° AOA, aftrer it does both pitch rate and AOA command

Wheel spin above 60 knots centers pitch trim.

 

Roll and Rudder trim may have to be change during flight depending on conditions and load out. Roll trim command proportional rudder trim trough the ARI. ARI does not work with wheel spin above 60 knots.

 

For example, here at 4:47 you can see the pilot reach behind him to input rudder trim. unfortunately we can not see the stick to see if he imputed any other trim.

The video is set just hit play

 

 

Edited April 19, 2021 by mvsgas
youtube link

[cmbaviator]

Not that I know of. The aircraft will maintain G no matter the throttle position, but you can climb or descend in 1 g. Roll and Rudder would depend on configuration and asymmetric load out will not be corrected automatically by the FLCC.

 

I posted here about the trim

 

 

For example, here at 4:47 you can see the pilot reach behind him to input rudder trim. unfortunately we can not see the stick to see if he imputed any other trim.

The video is set just hit play

RXnHnQZZqGs?start=287

 

why would he need rudder trim ? ASYMETRICAL Loads ?

 

if it tries to maintain 1G, then it should be flight path stable in certain conditions

[mvsgas]

Here you can see some video of flight testing the FBW, keep in mind that videos lack a lot of information and specifics. The videos do not tell us the block, the version of the FLCC or its software, was the flight FBW alter for the test, etc.

https://forums.eagle.ru/showpost.php?p=3775853&postcount=1143

 

https://forums.eagle.ru/showpost.php?p=3775880&postcount=1144

[mvsgas]

why would he need rudder trim ? ASYMETRICAL Loads ?

No clean aircraft AFAIK. It needs trim like any other aircraft in all axis.

 

if it tries to maintain 1G, then it should be flight path stable in certain conditions

In certain conditions, but does not mean the aircraft auto trims.

 

For example: Lets say the pilot set up pitch at "X" G at "Y" speed, changing that speed might affect the aircraft, making it climbs or descends. FLCC will not correct roll or yaw, when speaking within the confines of trim level flight.

[mvsgas]

Here, the aircraft appear to be Luke AFB Block 42 after CCIP (JHMCS video), at around 14:40 the pilot give control to the guy on the back seat ( not a pilot, guy is just getting a incentive flight) He tell him to pull power back, note that when speed drops the aircraft starts to descend.

When speed increases, note the aircraft starts climbing. Unfortunately, like all videos it lacks a lot of details and you can't see if the pilots had anything to do with the behavior.

 

At 20:16, the pilot does a 4 point roll, note how the nose drops.

At 26:00, the guy on the back mention how it leans to the right, and the pilot answer that he will trim it to correct it.

Edited August 21, 2019 by mvsgas
spelling

[cmbaviator]

You need to trim only the elevators on an aircraft in normal operations, unless you have a fuel, leak, misile fired... resulting in an unbalance aircraft.

[mvsgas]

You need to trim only the elevators on an aircraft in normal operations, unless you have a fuel, leak, misile fired... resulting in an unbalance aircraft.

 

Not sure what you trying to say, could you explain?

[cmbaviator]

Not sure what you trying to say, could you explain?

 

normally your aircraft is symetrically loaded and assuming its not a turboprop, you only need to trim the elevators except if it has autopitch trim like the A320 and above family.

 

Why would you need to trim the aileron or rudder ? unless you have one engine failure, asymetrical load, fuel leak....

 

 

I didn't understand why the F16 pilot needed to rudder trim his f16