No more CQs?

[Brett327]

Was monkeying with the flaps to that degree always in the Hornet/Rhino/Growler flight control laws, or was that part of PLM?

Can't speak to the legacy Hornet, but the LEF/TEF are always moving around to optimize - hence the "live wing" concept. It's especially pronounced at high alpha. It's one of the reasons the jet remains controllable at 70 Kts and 34 alpha. The engineers just took that inherent way the wing works and made it do PLM stuff. That's a technical term.

 

[Python]

Was monkeying with the flaps to that degree always in the Hornet/Rhino/Growler flight control laws, or was that part of PLM?

The best video on the topic. For your particular question, start at 7:32.

 

[jollygreen07]

Slight threadjack... who the hell calls them CHICOMS anymore? What is this, 1951?

Um... Me?

 

[sevenhelmet]

Was monkeying with the flaps to that degree always in the Hornet/Rhino/Growler flight control laws, or was that part of PLM?

Both, to a degree. LEF/TEF position has always been modulated in flaps AUTO while up and away, in order to optimize lift and turn perf across the flight envelope. In other words, leading and trailing edge flaps will droop during maneuvering flight, generally in response to increasing AOA.

The main thing PLM added was direct lift control during approaches by modulating TEF position. Previously, TEF position was a fixed number of degrees in HALF or FULL. In Rhino PLM, the LEFs are fixed in approach position, and the trailing edge provides direct lift control. I don't belive PLM has been added to the legacy (A-D) Hornet, although I have lost SA to developments on that aircraft since 2017. Can't speak at all to the -35.

 

[wink]

Um... Me?

I prefer CHICOM. But then I am also known to use Bitch'n, Wilco, Spiffy, Pinko, Dough, and Nork.

 

[Griz882]

I prefer CHICOM. But then I am also known to use Bitch'n, Wilco, Spiffy, Pinko, Dough, and Nork.

Dude...

 

[Jim123]

Slight threadjack... who the hell calls them CHICOMS anymore? What is this, 1951?

Well, CHICENTRALLYPLANNEDECONOMYCONFUCIANCAPITALISM doesn't exactly roll off the tongue.

The FBW system is pretty crazy compared to conventional flight controls. I spent the better part of a decade working on legacy fcs systems and learning about fcs control logic and Alpha v G-control at TPS blew my mind. And adding another flight surface configuration like PLM just makes things that much more "unconventional." When you realize a rhino pilot just suggests to the airplane what it should do then you can start understanding FWB. ?

There's a pretty noticeable difference between watching an Airbus product on short final on a windy day compared to a conventionally built large airplane. The Bus (and other FBW airplanes) flight control surfaces move more but the airplanes themselves appear nearly rock-steady; the normal airplanes' motion is a livelier but the flight controls move less.

When the F-14 fleet got its digital FCS upgrade (1990s) I remember hearing how the flight controls wiggled a lot more behind the boat, since it was a computer making lots and lots of tiny corrections. This caused some concern among LSOs because it also looked a lot like a bad approach when the pilot is wrestling with snakes in the cockpit. (DAFCS is artificial stabilization and not the same thing as FBW, but the end results have a few things common.) Similar idea to a strong yaw damper in turbulence or even the fast acting, inner loop flight control wigglers on some helicopter AFCS.

 

[IKE]

Other nerds, please correct me if I'm wrong, but fly-by-wire (FBW) simply means the pathway from inceptors (in-cockpit controls) to flight control surfaces has some portion which is electronic vice mechanical.

Mechanical flight control systems can have fancy AFCS effected by servos anywhere along the control pathway, from the inceptor all the way to the pushrod at the edge of the aileron, flap, rudder, etc. The EC725 has a pretty sweet auto approach to a GPS point at 50 ft AGL which makes a mockery of our Seahawk auto approach.

FBW doesn't necessitate fancy automatic modes, but since it's newer, and changes to those modes are (supposedly) easier to implement with just software, you tend to see much more AUTO stuff on FBW systems.

 

[Python]

Other nerds, please correct me if I'm wrong, but fly-by-wire (FBW) simply means the pathway from inceptors (in-cockpit controls) to flight control surfaces has some portion which is electronic vice mechanical.

Mechanical flight control systems can have fancy AFCS effected by servos anywhere along the control pathway, from the inceptor all the way to the pushrod at the edge of the aileron, flap, rudder, etc. The EC725 has a pretty sweet auto approach to a GPS point at 50 ft AGL which makes a mockery of our Seahawk auto approach.

FBW doesn't necessitate fancy automatic modes, but since it's newer, and changes to those modes are (supposedly) easier to implement with just software, you tend to see much more AUTO stuff on FBW systems.

Yes. FBW means control inputs direct a command (G-Command, AOA-command, Yaw-command, etc). Your commands will let the computers determine the output to achieve that, within limits. The stick and rudders link to the computer, not to the airplane per se (though the legacy hornet did have a MECH backup to the horizontal stabs, that the Rhino lacks, due to the rhino’s increased electrical redundancy).

 

[Jim123]

@IKE , short answer is yes but if you look at the "build the airplane" approach to studying the systems, compare the manual reversion mode in the F-18 to what I think of as the "puppet strings and hydraulic servos" construction of the H-60 flight controls and many other modern airplanes. Those flight control cables in the -60 nudge a little button that moves a pilot valve that makes for a big shot of hydraulic muscle that shoves the primary servo and moves the aerodynamic surface, and the computer helps you fly better mostly by doing something that basically wiggles the far end of that cable in a way the the pilot doesn't feel any feedback*... instead of a computer directly nudging that little button/pilot valve thingy on the primary servos.

It's a distinction with a difference, it's built differently from the drawing board on up, but it's also not completely different. When all the computers and hydraulics in an F-18 crap out, how do the control surfaces move when the pilot moves the control stick to make the airplane pitch or roll? They move the old way...

Unfortunately/obviously the H-60 is just a bit too big and heavy to have a true manual reversion mode- even if you had the world's strongest pilot, with total hydraulic failure then you'd just end up stretching the control cables (or breaking off the cyclic and collective sticks) and not actually moving the aerodynamic surfaces enough to matter. But in the case of many light helicopters, some of them fly okay with a total hydraulic failure and a bit of human muscle. (The reversion mode in the legacy F-18 is reportedly survivable but extremely challenging in real life.)


What's all this stuff matter for naval aviation? It matters for how not to get shot down.


* notwithstanding trim-related functions, which FBW and non-FBW implement pretty similarly

 

[Birdbrain]

So if I understand this correctly, not only are they looking at getting rid of CQ for the T-45 replacement sometime in the future, but they are also looking at getting rid of CQ for the T-45 in the near future? It sounds like PLM is becoming so redundant and accepted that if the jet can't fly a PLM pass you aren't going to be able to get aboard the boat anyway...this seems like a quantum leap from what I percieve as training us to be manual pilots in an increasingly automated field of aviation.

 

[HAL Pilot]

Yes. FBW means control inputs direct a command (G-Command, AOA-command, Yaw-command, etc). Your commands will let the computers determine the output to achieve that, within limits. The stick and rudders link to the computer, not to the airplane per se (though the legacy hornet did have a MECH backup to the horizontal stabs, that the Rhino lacks, due to the rhino’s increased electrical redundancy).

In the Airbus, the FBW has laws. The pilot commands the controls by moving the stick and the FBW determines how much to move the controls. Normal law is the highest and provides the most protections. If you direct the airplane out of certain angle of bank, angle of pitch or g limitations; it limits the flight controls so you won't exceed the programmed limits. I can yank the stick full back and leave it there and it will never hit stall AOA. You can't do steep turns in training in normal law because you can't bank it enough. If equipment breaks, it drops to a lower level of protect with alternate law still providing some protections and direct law not providing any. In direct law, the flight controls do exactly what the pilot tells it to do.

Similarly we have "FBW" throttles, "FBW" brakes and "FBW" nose wheel steering. The steering and brakes are interesting because it depends on the rate of peddle depression or tiller movement vice the amount. I can push the brakes all the way to the floor really slowly and not slow at all or I can barely tap them quickly and stand the plane on its nose. Throttles are easy but the steering and brakes take a while to get used to.

Anyway, for flight controls FBW is just how the control inputs get to the control surfaces. All the magic stuff is handled by the computer also attached into the system.

 

[SynixMan]

So if I understand this correctly, not only are they looking at getting rid of CQ for the T-45 replacement sometime in the future, but they are also looking at getting rid of CQ for the T-45 in the near future? It sounds like PLM is becoming so redundant and accepted that if the jet can't fly a PLM pass you aren't going to be able to get aboard the boat anyway...this seems like a quantum leap from what I percieve as training us to be manual pilots in an increasingly automated field of aviation.

It’s not just about the T-45. It eliminates a chunk of the syllabus in advanced, allowing them to get pilots to the fleet faster. It also frees up precious carrier underway time from a fleet that is tired from 20 years of wartime surge deployments. If the Air Boss, NAVAIR, and others agreed to this, I’m sure a lot of sue diligence was done.

I’ll also add that reducing CQ requirements from the 45’s replacement allows you to eliminate a big design hurdle. You can spend that on making something that covers a lot of bases for adversary and training work, further strengthening the fleet.

 

[brownshoe]

It’s not just about the T-45. It eliminates a chunk of the syllabus in advanced, allowing them to get pilots to the fleet faster. It also frees up precious carrier underway time from a fleet that is tired from 20 years of wartime surge deployments. If the Air Boss, NAVAIR, and others agreed to this, I’m sure a lot of sue diligence was done.

I’ll also add that reducing CQ requirements from the 45’s replacement allows you to eliminate a big design hurdle. You can spend that on making something that covers a lot of bases for adversary and training work, further strengthening the fleet.

Not in my day! Now I'm really gonna show my age. I can't even count the times I worked the deck of the Lady Lex. Some of you other old farts know what I'm talkin' 'bout.

 

[wlawr005]

So if I understand this correctly, not only are they looking at getting rid of CQ for the T-45 replacement sometime in the future, but they are also looking at getting rid of CQ for the T-45 in the near future? It sounds like PLM is becoming so redundant and accepted that if the jet can't fly a PLM pass you aren't going to be able to get aboard the boat anyway...this seems like a quantum leap from what I percieve as training us to be manual pilots in an increasingly automated field of aviation.

The T45 replacement, even if it's the T-7, won't hit the streets until well into the late '20s. Advanced flight students will have stopped going to the boat long before that.