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Hornet stick feeling in the aircraft...


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Hi all,

 

Got a quick question here that might be more focused to whoever flew the real jet...

 

I have several stick bases, and swap sticks according to my need. One of those, is dedicated to the hornet. It's a Virpil Warbrd with an 8cm extension and a Thrustmaster f/a18 stick on it.

Thing is, I would like to dial the feeling closer to what you have in the jet itself by setting the closest cam profile and spring tension (although spring is an easy setting, I just put the heavier ones but since the plane is a FBW essentially, one might be surprised by lack of feedback) .

Viral has 2 sets of cams I can use for aero sims: Linear with center bump or progressive towards hard edges without bump.

 

So, the questions: - In the Jet, is the stick rather linear in it's displacement or does it get harder towards the limits of it's gimbals?

- Is there a "bump" in the neutral position or can you move the stick freely without feeling a small "detent" when you go across the neutral psn?

 

I looked at NATOPS but it's not really the kind of info to find there, the diagram of the FCS shows the stick having a pitch and roll feel spring but other then that not a lot of info on how it translates to stick movement and feeling or neutral bump in stick design.

 

All planes I flew were different by design it the way it feels in your hand. The 737 for example, you can feel a small detent in neutral roll but not in pitch (due to column design obviously).

So it would be nice if somebody can give me a hint on the hornet about this...

 

Thanks in advance,

 

Best regards

Rig: MB Gigabite z390UD, CPU Intel I7 8700k, RAM 32G DDR4 3200 Gskill ripjaws, GPU MSI RTX2080SuperOC, HDD Crucial mx500 1tb M2 sata, PSU Corsair 850W, watercooling Corsair h100,

 

Controlers TM f/a 18 stick on Virpil warbrd base, TM cougar f16 stick on cougar base, Cougar F16 throttle on TUSBA, ch pedals, TM cougar MFD

 

27" monitor with trk IR 5 and HP Reverb HMD.

 

 

Modules F18, F16, F86, Mig15, FW 190D9, Nellis range map, Aggr campaign, Middle East map

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Hello,

No force sensor in the hornet, it's FBW (with backups DEL and Mech that we dont have in dcs) allright but it moves. Just look at youtube videos of the controls swipe before cat shots...

 

Best regards

Rig: MB Gigabite z390UD, CPU Intel I7 8700k, RAM 32G DDR4 3200 Gskill ripjaws, GPU MSI RTX2080SuperOC, HDD Crucial mx500 1tb M2 sata, PSU Corsair 850W, watercooling Corsair h100,

 

Controlers TM f/a 18 stick on Virpil warbrd base, TM cougar f16 stick on cougar base, Cougar F16 throttle on TUSBA, ch pedals, TM cougar MFD

 

27" monitor with trk IR 5 and HP Reverb HMD.

 

 

Modules F18, F16, F86, Mig15, FW 190D9, Nellis range map, Aggr campaign, Middle East map

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Hi all,

 

Got a quick question here that might be more focused to whoever flew the real jet...

 

I have several stick bases, and swap sticks according to my need. One of those, is dedicated to the hornet. It's a Virpil Warbrd with an 8cm extension and a Thrustmaster f/a18 stick on it.

Thing is, I would like to dial the feeling closer to what you have in the jet itself by setting the closest cam profile and spring tension (although spring is an easy setting, I just put the heavier ones but since the plane is a FBW essentially, one might be surprised by lack of feedback) .

Viral has 2 sets of cams I can use for aero sims: Linear with center bump or progressive towards hard edges without bump.

 

So, the questions: - In the Jet, is the stick rather linear in it's displacement or does it get harder towards the limits of it's gimbals?

- Is there a "bump" in the neutral position or can you move the stick freely without feeling a small "detent" when you go across the neutral psn?

 

I looked at NATOPS but it's not really the kind of info to find there, the diagram of the FCS shows the stick having a pitch and roll feel spring but other then that not a lot of info on how it translates to stick movement and feeling or neutral bump in stick design.

 

All planes I flew were different by design it the way it feels in your hand. The 737 for example, you can feel a small detent in neutral roll but not in pitch (due to column design obviously).

So it would be nice if somebody can give me a hint on the hornet about this...

 

Thanks in advance,

 

Best regards

 

I haven't flown one but I know the stick forces required increase further you go from the center.

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All I know is that Lex thinks TMWH with its linear force is the best representation of the real thing.

 

Does he use an extension or a different spring if no extension? I never would have thought a stock Warthog feels like a fbw plane like the Hornet.

Buzz

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Thanks all, that's already a start. So no center thunk in the hornet stick. right?

Rig: MB Gigabite z390UD, CPU Intel I7 8700k, RAM 32G DDR4 3200 Gskill ripjaws, GPU MSI RTX2080SuperOC, HDD Crucial mx500 1tb M2 sata, PSU Corsair 850W, watercooling Corsair h100,

 

Controlers TM f/a 18 stick on Virpil warbrd base, TM cougar f16 stick on cougar base, Cougar F16 throttle on TUSBA, ch pedals, TM cougar MFD

 

27" monitor with trk IR 5 and HP Reverb HMD.

 

 

Modules F18, F16, F86, Mig15, FW 190D9, Nellis range map, Aggr campaign, Middle East map

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I haven't flown one but I know the stick forces required increase further you go from the center.

 

Well, you made me look it up... It's a function of 'g' and AOA. When parked on the ground and hyds running, there is probably not that much change throughout the range.

 

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Well, you made me look it up... It's a function of 'g' and AOA. When parked on the ground and hyds running, there is probably not that much change throughout the range.

 

The way I understand it, the force per distance remains the same, as does the G/AOA per force. Which means slower speeds will mean more surface movement per force in order to reach the same G. If that makes sense

 

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The way I understand it, the force per distance remains the same, as does the G/AOA per force. Which means slower speeds will mean more surface movement per force in order to reach the same G. If that makes sense

 

Years ago someone was explaining this to me, perhaps we were talking about a different jet;)

 

Anyways, w/o searching the whole NFM000... this paragraph mentions the subject:

 

IV-11-3

"11.1.5 Stick Force. In maneuvering flight, there is a light but constant stick force per g (about 3.5 to 4.5 pounds/g). Unlike many other aircraft, maneuvering stick forces do not vary significantly over the entire operating envelope as long as the AOA is less than AOA feedback of 22°. Where AOA feedback is active, maneuvering stick forces are increased significantly."

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Hello,

No force sensor in the hornet, it's FBW (with backups DEL and Mech that we dont have in dcs) allright but it moves. Just look at youtube videos of the controls swipe before cat shots...

 

Best regards

 

That’s not correct. The stick moves, so does the the F-15’s...and they both have a stick force sensor (base of the stick) that translates force pressure to the CAS computers and into flight control movements. It’s a typical MD/Boeing design.

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Aaah so it is a force sensor unit translating movement into signal.... good to know.

I was thinking at a force sensing ala f16 that will register force on a device (here the stick) without alowing it to move...

Thanks for the info ;)

 

Rig: MB Gigabite z390UD, CPU Intel I7 8700k, RAM 32G DDR4 3200 Gskill ripjaws, GPU MSI RTX2080SuperOC, HDD Crucial mx500 1tb M2 sata, PSU Corsair 850W, watercooling Corsair h100,

 

Controlers TM f/a 18 stick on Virpil warbrd base, TM cougar f16 stick on cougar base, Cougar F16 throttle on TUSBA, ch pedals, TM cougar MFD

 

27" monitor with trk IR 5 and HP Reverb HMD.

 

 

Modules F18, F16, F86, Mig15, FW 190D9, Nellis range map, Aggr campaign, Middle East map

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Aaah so it is a force sensor unit translating movement into signal.... good to know.

I was thinking at a force sensing ala f16 that will register force on a device (here the stick) without alowing it to move...

Thanks for the info ;)

 

Everyone always associates force sensing to the F-16 because of the reduced movement vs other center stick jets. The reality is, many of them use relatively the same concept to talk to the flight control computers.

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Everyone always associates force sensing to the F-16 because of the reduced movement vs other center stick jets. The reality is, many of them use relatively the same concept to talk to the flight control computers.

 

Viper uses pure force sensing (transducer). Hornet also uses stick position as a factor. It looks a bit more complex to me.

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Viper uses pure force sensing (transducer). Hornet also uses stick position as a factor. It looks a bit more complex to me.

 

Yes and no. CAS is less dependent on actual stick movement. It’s using force sensors to translate the inputs. Reading a -1, NOTOPS, etc is a bit different than translating it to what is actually happening.

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Yes and no. CAS is less dependent on actual stick movement. It’s using force sensors to translate the inputs. Reading a -1, NOTOPS, etc is a bit different than translating it to what is actually happening.

 

The Hornet's stick forces get adjusted depending on feedback from air data comp. (AOA, g) In the Viper you don't get any feedback/feel on the stick. I guess OP was mainly asking about the stick forces in the Hornet.

 

And... as far as me reading:lol: I wish I spent more time reading... recently, I only get motivated to peek into these manuals when something comes up that stirs up my curiosity.

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The Hornet's stick forces get adjusted depending on feedback from air data comp. (AOA, g) In the Viper you don't get any feedback/feel on the stick. I guess OP was mainly asking about the stick forces in the Hornet.

 

And... as far as me reading:lol: I wish I spent more time reading... recently, I only get motivated to peek into these manuals when something comes up that stirs up my curiosity.

 

What is written in natops does not suggest that. As you yourself wrote, there is a constant stick force per G. Obviously we need someone who has flown it to chip in here, but the way I read that is that the G is scheduled depending on how much force you are applying to the pitch and roll feel springs, regardless of the position of the stick through its travel.

 

So whenever you apply 7lbs the stick will move the same amount regardless of flight conditions. However the FCC will work to provide 3g, by moving the control surfaces as required to achieve that for the given flight conditions. Excluding the AOA>22 condition of course.

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What is written in natops does not suggest that. As you yourself wrote, there is a constant stick force per G. Obviously we need someone who has flown it to chip in here, but the way I read that is that the G is scheduled depending on how much force you are applying to the pitch and roll feel springs, regardless of the position of the stick through its travel.

 

So whenever you apply 7lbs the stick will move the same amount regardless of flight conditions. However the FCC will work to provide 3g, by moving the control surfaces as required to achieve that for the given flight conditions. Excluding the AOA>22 condition of course.

 

So, starting to get in the weeds here and a bit more in depth than the OP was asking but...

 

My question with that topic is whether the -18 has a pitch ratio function as the -15 does. By design, the -15 adjusts itself so the same stick pressure gives you the same G regardless of things like speed, etc....until you get slow enough where you really can’t meet the request by the pilot. That’s one of the bigger things missing with the -15’s FM, and I don’t know if the -18 is also missing this as I don’t know if they are supposed to function in the same manner. The above gives the pilot a a good source of feedback to know where to pit the stick in order to command X amount of G regardless of where he/she is in the flight envelope, so you don’t have to steadily pull the stick back until you get what you want. The -18 is a bit different in that is has a limiter, but they could still be designed that way...or not. The books available really don’t go that deep in the weeds on it, but the above that you are mentioning kind of hints towards it. Someone with personal knowledge of the -18’s stuff may be able to clear that one up. I can only speculate based on the two airframes sharing some similarities already.

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So, starting to get in the weeds here and a bit more in depth than the OP was asking but...

 

My question with that topic is whether the -18 has a pitch ratio function as the -15 does. By design, the -15 adjusts itself so the same stick pressure gives you the same G regardless of things like speed, etc....until you get slow enough where you really can’t meet the request by the pilot. That’s one of the bigger things missing with the -15’s FM, and I don’t know if the -18 is also missing this as I don’t know if they are supposed to function in the same manner. The above gives the pilot a a good source of feedback to know where to pit the stick in order to command X amount of G regardless of where he/she is in the flight envelope, so you don’t have to steadily pull the stick back until you get what you want. The -18 is a bit different in that is has a limiter, but they could still be designed that way...or not. The books available really don’t go that deep in the weeds on it, but the above that you are mentioning kind of hints towards it. Someone with personal knowledge of the -18’s stuff may be able to clear that one up. I can only speculate based on the two airframes sharing some similarities already.

 

Until the Hornet guy chimes in... more text:book:

 

Same 'dreary' book - 2.10.5.1

"In UA, with neutral longitudinal stick, comparing pilot input to aircraft response has the effect of constantly trimming the aircraft to steady-state, hands-off 1g flight, essentially removing the requirement for manual trim. In maneuvering flight, P CAS modifies aircraft response to stick inputs creating the effect of changing stick forces to provide pilot cueing. Actual stick forces for a given stick displacement do not change with flight condition. At high airspeeds, P CAS is a g-command system requiring 3.5 pounds of stick-force-per-g. At medium airspeeds, P CAS acts as a hybrid pitch rate and g-command system. Pitch rate feedback is used to increase apparent stick-force-per-g (heavier stick forces) to cue the pilot that airspeed is decreasing and less g is available. At low airspeed, P CAS is primarily an AOA command system using AOA feedback above 22° AOA to provide increasing stick forces with increasing AOA. With large forward stick inputs, P CAS augments nose-down pitch rates by flaring the rudders and raising the spoilers."

 

 

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Viper uses pure force sensing (transducer).

I researched the Viper stick (wanted to make a DIY equivalent with realistic mechanics), and I was very surprised it actually doesn't. This might have been the case in early prototypes, but in actual service the Viper's stick uses LDVTs, which are linear position sensors. They're just very precise position sensors. In a way, every realistic flight stick senses force - it takes more force to move the stick further. The Viper just tries to replicate this with a low displacement sidestick, and so has a steel bar for the mainspring, which you have to bend to deflect the stick. The bar bends, and actuates the two LDVTs.

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I researched the Viper stick (wanted to make a DIY equivalent with realistic mechanics), and I was very surprised it actually doesn't. This might have been the case in early prototypes, but in actual service the Viper's stick uses LDVTs, which are linear position sensors. They're just very precise position sensors. In a way, every realistic flight stick senses force - it takes more force to move the stick further. The Viper just tries to replicate this with a low displacement sidestick, and so has a steel bar for the mainspring, which you have to bend to deflect the stick. The bar bends, and actuates the two LDVTs.

 

Interesting. I imagine the 'new' Viper blocks are quite a bit different. By 'new' I meant a decade or 2 old:)

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There are few really good open source documents on the Hornet’s FCS. The best and most recent is from NASA. It describes the system as follows

https://ntrs.nasa.gov/archive/nasa/c...9920024293.pdf

 

“The pitch CAS uses a pilot commanded longitudinal stick position input as a command to the CAS. The forward path gain is air data scheduled (Function 32A) to yield a uniform initial pitch acceleration response for sharp inputs. The CAS feedback parameters are a blend of air data scheduled pitch rate (Functions 40 and 68, normal acceleration, and angle of attack. Pitch rate and normal acceleration feedbacks give improved pitch dynamic characteristics and load factor control in the mid to high dynamic pressure portion of the flight envelope. Air combat maneuvering characteristics and increased stick-force-per-g cues in the low to mid dynamic pressure flight regime are provided by the air data scheduled pitch rate feedback. Angle-of-attack feedback provides additional increased stick force cues for low speed high angle-of-attack air combat maneuvering. Roll rate multiplied by yaw rate is fed to the longitudinal control system (Function 107) to reduce the effects of inertial coupling. “

 

So yes it does have a similar function as the pitch ratio changer on the F-15. Many of the same people worked on both systems, F-15, F/A-18, at MDC. (Abercrombie, Harschburger)

 

http://aviationarchives.blogspot.com...8-growing.html

https://ocw.mit.edu/courses/aeronaut...controls_1.pdf

https://ocw.mit.edu/courses/aeronaut...controls_2.pdf

 

Since the NASA doc provides the air data schedules, you can see how the gains change based on air data. Where Pitch rate, G and angle of attack feedbacks become more dominate. Thus effecting the stick forces per G.

 

In this older report you can see how the system iterates via the program and diagrams, How the sensor inputs effect stabilator, position when Air data is fixed and the stick is held aft. However this particular version of the system does use an older gain schedule and force inputs for stick command. All of which was later changed. So while it gives a nice overview of how system responds it’s not accurate to the current system.

 

https://apps.dtic.mil/sti/pdfs/ADA140143.pdf

 

An even older version of the FCS is available here. You can track and see how the gains change as the FCS is updated. Some of which are deleted.

 

https://apps.dtic.mil/sti/pdfs/ADA176333.pdf

 

Which is why you have to aware of the dates of when these papers are published and what version of the FCS they are referring to. As handling qualities changed with FCS updates.

 

http://aviationarchives.blogspot.com...8-growing.html

https://apps.dtic.mil/dtic/tr/fulltext/u2/p002709.pdf

https://ocw.mit.edu/courses/aeronaut..._mit_brief.pdf

 

 

However if your looking for a baseline stick force gradient one is available.

 

https://apps.dtic.mil/dtic/tr/fulltext/u2/a256522.pdf

 

Break out forces of +-3.0 lbs and a stick force gradient of 7.4 lbs and inch. With stick moving 5 inch aft and 3 inches forward in the Up and away.

 

Gripes your quotes if from the super hornet NATOPS. There are some differences in the FCS between both craft. The one that stands out in your quote is the use of rudder toe in UA flight. This was never added to the legacy hornet.

 


Edited by Curly
grammer, added a link
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