what's going on with the pitch control?

[FlankerKiller]

54 minutes ago, shagrat said:

"Technically" every aircraft that has an electronic component, that controls the hydraulic or mechanical connection to the control surfaces is "FBW" (basically a stick that uses a potentiometer to steer a servo-motor that moves the control surface is "FBW").

In today's terms FBW in combat aircraft usually refers to the controls being managed, linked and optimized by a flight computer. Any augmentation system (SCAS,SAS,CAS) typically has a very limited authority over some or all control surfaces, in order to filter, dampen or compensate pilot inputs in favor of flight stability. A "real" (common term) FBW system typically controls all or at least most controls with way more authority to limit or correct pilot inputs in a certain regime and calculates adjustments to all surfaces to prevent departure from controlled flight... At least that is my take on the FBW terminology.

So an F-15/F-15E may technically be called FBW, but it is a very different FBW than in the F-16C, Eurofighter Typhoon or Rafale, etc.

Ok this is off topic, and this is my last post. I'm an A&P holder that spent the last 17 years specialized in aircraft electrical systems. It's dumb but it annoys me when people use terms incorrectly. Fly by wire is the name for a system where the control inputs are sent as an electrical signal to a flight control computer that Interprets the signal and then moves the flight controls. There is no physical connection between the controls in the cockpit and the hydraulic/ electrical components that actuate the control surfaces. I've actually installed and calibrated the potentiometers you are talking about many times. And that jet used a triple redundant hydraulic flight controls system with a stability augmentation system. It was not Fly By Wire. By your definition the F-5E is Fly By Wire because is has a SAS. To be clear you could theoreticaly have a controls stick that uses potentiometers to DIRECTLY control servo motors that actuate the flight controls surfaces and it still isn't a Fly By Wire system. The presence of the flight control computer that actually "fly" the aircraft is what defines FWB systems. To bring it all back to the OP's problem. It seems he or she is used to the Hornet. A fully fly by wire jet. I say fully because some aircraft use a hybrid system, example the JF-17. The Hornet's flight control computer flys the jet. It's noticeable if your used to older aircraft in DCS. It dose alot of the work for you, and it dampens out alot of ham fisting. The F-15, except for the EX is not FEB. It has a hydro mechanical flight controls system that had a CAS "bolted" on to it. But YOU are flying the F-15, not a flight control computer. You have to use trim, although it's Is aided by the CAS and very refined, you can fly the jet into destruction. YOU have the control authority. If someone has only been flying the Hornet, or Viper, or M2000C then the Strike Egale is going to feel vary weird. That is my entire point. 

[Father Cool]

I don't know, I'm a cat pilot and whilst I love how the 15 is flying in the most part I do see what the OP is saying regarding nose bob. The cat never does this and I'm trimming that bad boy every 2 seconds to keep it right. The 15 however as soon as you release to centre stick regardless of trimming  the nose bobs down and then up and then down then up and then settles. Never had that happen in the tomcat.

[shagrat]

vor 12 Minuten schrieb FlankerKiller:

Ok this is off topic, and this is my last post. I'm an A&P holder that spent the last 17 years specialized in aircraft electrical systems. It's dumb but it annoys me when people use terms incorrectly. Fly by wire is the name for a system where the control inputs are sent as an electrical signal to a flight control computer that Interprets the signal and then moves the flight controls. There is no physical connection between the controls in the cockpit and the hydraulic/ electrical components that actuate the control surfaces. I've actually installed and calibrated the potentiometers you are talking about many times. And that jet used a triple redundant hydraulic flight controls system with a stability augmentation system. It was not Fly By Wire. By your definition the F-5E is Fly By Wire because is has a SAS. To be clear you could theoreticaly have a controls stick that uses potentiometers to DIRECTLY control servo motors that actuate the flight controls surfaces and it still isn't a Fly By Wire system. The presence of the flight control computer that actually "fly" the aircraft is what defines FWB systems. To bring it all back to the OP's problem. It seems he or she is used to the Hornet. A fully fly by wire jet. I say fully because some aircraft use a hybrid system, example the JF-17. The Hornet's flight control computer flys the jet. It's noticeable if your used to older aircraft in DCS. It dose alot of the work for you, and it dampens out alot of ham fisting. The F-15, except for the EX is not FEB. It has a hydro mechanical flight controls system that had a CAS "bolted" on to it. But YOU are flying the F-15, not a flight control computer. You have to use trim, although it's Is aided by the CAS and very refined, you can fly the jet into destruction. YOU have the control authority. If someone has only been flying the Hornet, or Viper, or M2000C then the Strike Egale is going to feel vary weird. That is my entire point. 

That's basically what I said... Minus the fact that the very first "Fly-by-wire" designs (no physical linkage between pilot input and control surface) didn't have a computer for a lack of computers, which were yet to be invented...

[Theodore42]

2 hours ago, shagrat said:

That's basically what I said... Minus the fact that the very first "Fly-by-wire" designs (no physical linkage between pilot input and control surface) didn't have a computer for a lack of computers, which were yet to be invented...

Maybe you're thinking of flight control systems to aid in control of the aircraft, like the F-15's CAS or the P-51's trim tabs being interconnected between the stick and control surfaces to lighten the load. Technically fly by wire is the last step in that progression. The stick is designed to best manipulate the aircraft and then it is plugged into a computer that controls the control surfaces exactly as you want. When a pilot uses a fly-by-wire system, he isn't flying an airplane, he's making a philosophical argument 

2 hours ago, Father Cool said:

I don't know, I'm a cat pilot and whilst I love how the 15 is flying in the most part I do see what the OP is saying regarding nose bob. The cat never does this and I'm trimming that bad boy every 2 seconds to keep it right. The 15 however as soon as you release to centre stick regardless of trimming  the nose bobs down and then up and then down then up and then settles. Never had that happen in the tomcat.

The F-15E has a really heavy nose because of sensors... also the F-15 was designed for air superiority. Maybe with all the extra sensors, equipment, ordinance and CFTs the center of gravity is a little far forward compared to similarly sized and maneuverable aircraft, like the A-10 or Su-25, both of which have very different airframes than the F-15.

The F-15E airframe was put into a role it wasn't quite designed for so maybe some nose bobs are a side effect. I've heard pilots say PIO happens easy in the F-15E.

[shagrat]

vor einer Stunde schrieb Theodore42:

Maybe you're thinking of flight control systems to aid in control of the aircraft, like the F-15's CAS or the P-51's trim tabs being interconnected between the stick and control surfaces to lighten the load. Technically fly by wire is the last step in that progression. The stick is designed to best manipulate the aircraft and then it is plugged into a computer that controls the control surfaces exactly as you want. When a pilot uses a fly-by-wire system, he isn't flying an airplane, he's making a philosophical argument 

 

I am not thinking much at all. It's how the "technical" definition of Fly-by-wire differentiates it.

It was mostly a cheeky comment to FlankerKillers:

(...)"In the interest of pedantry, CAS is technically a FBW system (there are force transducers in the stick like the F-16), and if the mechanical linkages are all shot out, the plane is still controllable (although both the mechanical and CAS are needed for full control AFAIK)."(...)

Per the "technical definition" and being pedantic the first Fly-by-wire systems where electrically controlled Servo-motors that actuated, control surfaces without mechanical linkage (rods or pull-wires).

By that definition every plane with a SAS, SCAS or CAS would be a FBW aircraft. I guess we all agree, today we define FBW, more precisely as an aircraft that has a flight computer that interprets pilot inputs and adjusts, overrides or reduce the inputs to the control surfaces to enhance stability and allow inherently unstable aircraft designs to be controlled at all.

So while "technically", per definition the F-15E qualifies as sporting a Fly-by-wire system in form of the CAS, it isn't anything like the F-16C or F/A-18C systems.

Edited July 13, 2023 by shagrat

[jaylw314]

5 hours ago, shagrat said:

"Technically" every aircraft that has an electronic component, that controls the hydraulic or mechanical connection to the control surfaces is "FBW" (basically a stick that uses a potentiometer to steer a servo-motor that moves the control surface is "FBW").

In today's terms FBW in combat aircraft usually refers to the controls being managed, linked and optimized by a flight computer. Any augmentation system (SCAS,SAS,CAS) typically has a very limited authority over some or all control surfaces, in order to filter, dampen or compensate pilot inputs in favor of flight stability. A "real" (common term) FBW system typically controls all or at least most controls with way more authority to limit or correct pilot inputs in a certain regime and calculates adjustments to all surfaces to prevent departure from controlled flight... At least that is my take on the FBW terminology.

So an F-15/F-15E may technically be called FBW, but it is a very different FBW than in the F-16C, Eurofighter Typhoon or Rafale, etc.

Yeah, the clinically pedantic like me would clarify whether something is 'full-authority' FBW or not, but I think when people talk about it that's what they usually mean.  The description of the F-15 CAS is that it gives you "limited" aircraft control  as opposed to "very limited" without the mechanical controls.  Not that those are terribly technical terms, but I'm guessing few people would volunteer to test that a plane with the mechanical controls intentionally removed  

[KlarSnow]

The CAS has 1/3rd control surface movement authority. So if you move the stick full aft and the CAS decides that’s the wrong thing, you only get 2/3rds the deflection. It uses this to create artificial feel in certain situations to provide feedback for impending situations.

The stall inhibitor is one example of this. As you get below a certain speed the CAS reduces your elevator movement for stick movement slightly, resulting in the nose feeling “heavier” Think as you move the stick aft, the CAS programs some of that out in order to make it feel like more stick movement is required in order to reach a stall condition.

We actually do test the CAS on itself as a show and tell during the B course, pilot or WSO locks the stick between their knees then the opposite cockpit will do a few maneuvers using just the force sensor. Works but again you are only getting 1/3rd control authority so you aren’t going to be doing anything super aggressive with it.

[shagrat]

vor 5 Stunden schrieb jaylw314:

 but I'm guessing few people would volunteer to test that a plane with the mechanical controls intentionally removed  

Yep, not really...

[jaylw314]

8 hours ago, KlarSnow said:

The CAS has 1/3rd control surface movement authority. So if you move the stick full aft and the CAS decides that’s the wrong thing, you only get 2/3rds the deflection. It uses this to create artificial feel in certain situations to provide feedback for impending situations.

The stall inhibitor is one example of this. As you get below a certain speed the CAS reduces your elevator movement for stick movement slightly, resulting in the nose feeling “heavier” Think as you move the stick aft, the CAS programs some of that out in order to make it feel like more stick movement is required in order to reach a stall condition.

We actually do test the CAS on itself as a show and tell during the B course, pilot or WSO locks the stick between their knees then the opposite cockpit will do a few maneuvers using just the force sensor. Works but again you are only getting 1/3rd control authority so you aren’t going to be doing anything super aggressive with it.

Cool beans! it's nice to have some perspective on its authority, thanks!

[draconus]

@jaylw314You're right about trim - it doesn't work like in the classic aircraft like Mustang or Tomcat where it's trimmed for the current speed and altitude. Here we just set the G and it is kept no matter the speed/alt just like in F-15C.

The double seaters (B/D, E) are known for a bit worse alpha and heavier nose behavior but the nose bobbing here works a bit different than in other aircraft. In the F-15C and F-14 the nose just goes back to the last neutral state after pulling the stick and letting it go. The F-15E actually moves (CAS?) the stabilators the other way for a moment - is this intended?

@FlankerKillerUnless you use AP/ACLS it's always the pilot who flies the aircraft no matter if it's mechanical, CAS or FBW.

[Bremspropeller]

20 hours ago, FlankerKiller said:

The presence of the flight control computer that actually "fly" the aircraft is what defines FWB systems.

The transmission of flight control commands purely via electrical signals is what defines FBW.

The "flight control computer" is just an evolutionary step that came into being with relaxed stability and special and more sythetic flight control laws (like g-command, pitch-rate or AoA-command and roll-rate command). We can dicuss about where an AFCS or Stab Aug and a flight control computer transition from one the other, but that discussion is fairly moot in my opinion.

The Mirage F1, for example, is FBW in pitch and yaw only, where it's mechanical controls are de-clutched in the normal flight mode, but can be re-engaged for mechanical control. Similar flight-control architectures (FBW primary with a mechanical back-up) were used for other early iterations of FBW aircraft. Such as the Vigilante. Or the Avro Vulcan. Or Concorde.

[av8orDave]

As an update, just based on my personal experience: I’ve been struggling with the pitch control, mainly on takeoff during rotation (the nose wheel becomes “unstuck” from the ground and the nose then wildly oscillates). A few days ago I got a Winwing Orion 2 F-18 stick (I had been using a TM Warthog). The Winwing has no distinct centering action like the TM does, and the pitch control issue immediately disappeared. This isn’t a Winwing advertisement, but it is interesting to note that hardware can make a big difference. The other nice improvement is in aerial refueling, where the tiny control inputs needed are way easier without the stick trying to force itself back to center. Just an FYI.

[FlankerKiller]

13 minutes ago, davidrbarnette said:

As an update, just based on my personal experience: I’ve been struggling with the pitch control, mainly on takeoff during rotation (the nose wheel becomes “unstuck” from the ground and the nose then wildly oscillates). A few days ago I got a Winwing Orion 2 F-18 stick (I had been using a TM Warthog). The Winwing has no distinct centering action like the TM does, and the pitch control issue immediately disappeared. This isn’t a Winwing advertisement, but it is interesting to note that hardware can make a big difference. The other nice improvement is in aerial refueling, where the tiny control inputs needed are way easier without the stick trying to force itself back to center. Just an FYI.

That could be why I didn't see it. I have a VKB Gunfighter with the soft center space cams installed. Yes hardwares matters, especially in helicopters. 

[Raven (Elysian Angel)]

3 hours ago, FlankerKiller said:

with the soft center space cams installed

Interesting idea! I'll go test that as well

[av8orDave]

I'll add that although a bit off-topic (kind of?), the super-tight centering action on the TM Warthog stick is pretty awful and unrealistic. It kind of "pops" into and out of the center of the range, whereas real aircraft have a very smooth transition, and a pretty minimal "centering" feel if one at all.

I think this makes takeoffs and air-to-air refueling pretty tough, or at least harder than it needs to be in DCS.

Edited July 14, 2023 by davidrbarnette

[jaylw314]

4 hours ago, davidrbarnette said:

As an update, just based on my personal experience: I’ve been struggling with the pitch control, mainly on takeoff during rotation (the nose wheel becomes “unstuck” from the ground and the nose then wildly oscillates). A few days ago I got a Winwing Orion 2 F-18 stick (I had been using a TM Warthog). The Winwing has no distinct centering action like the TM does, and the pitch control issue immediately disappeared. This isn’t a Winwing advertisement, but it is interesting to note that hardware can make a big difference. The other nice improvement is in aerial refueling, where the tiny control inputs needed are way easier without the stick trying to force itself back to center. Just an FYI.

FWIW the WW Orion stick's alternate cams give you a pretty good choice between no center detent, strong detent, and barely palpable detent.  They're not cheap, but worth getting to play around with if you have other stuff to order from them!   AFAIK VKB and Virpil have similar cam kits for their sticks

[Raven (Elysian Angel)]

Yes Virpil bases ship with 4 types of CAMs and 3 springs, 1 of each pre-installed.

[FlankerKiller]

3 hours ago, Raven (Elysian Angel) said:

Interesting idea! I'll go test that as well

So far I like it. The soft aviation cam was great for helicopters. But wad to soft for to long with fixed wing. The hard center aviation cam was a little to hard center. Maybe if I had ring it with light springs. I'm running two 40's on each axis. I like the way the soft center space cam gives me enough of a soft center to hover a trimed out helicopters with just the tips of my finger. But it gets more stiff as you move away from center in a linear fashion. I think it helps me feel where the stick is. I abhor the use of curves. 

[Raven (Elysian Angel)]

2 hours ago, FlankerKiller said:

The soft aviation cam was great for helicopters.

I have 2 Virpil bases: 1 for fixed wing and 1 for rotary. My rotary base uses a no-centre cam. You are right that the take-off wobble disappears with this cosmo-cam, but it feels weird to use for fixed wing since there is no increasing force the more you pull the stick. I tested it with the F-15E, F-18 and F-14. I'll likely go back to the normal cam if I can't get used to it...

[FlankerKiller]

It's all personal taste for sure. I wish I could have two setups lol. The closest I get is I use my old Gladiator NXT in a side stick configuration for the Viper. Glad that you got the pitching issue under control. This module is going to be a blast once it gets the first released bugs worked out. 

[River]

The nose bob needs to be worked on and the takeoff is weird. It's like she's glued onto the runway.

I have the same in the Mirage 2000 and the Harrier. A smooth takeoff is basically not possible. It's a hopping down the runway till you get to a point where it feels like a scripted event getting off the tarmac. Mirage has a left right wobble on top during takeoff roll.

Mig 21 has it too btw, the takeoff feels so scripted, there is no control when you lift the front tire and send her of the runway.

Without wind and turbulence in the mission it gets better. Maybe Razbam has trouble with wind, turbulences and tire friction, IDK.

I just wish Razbams modules would takeoff like the F 16, F 18, L 39, etc.

It's so much joy and smooth.

Tomcat is a hard to takeoff smooth but it's perfectly doable if you have some time in the jet. 

Edited July 19, 2023 by River

[draconus]

2 hours ago, River said:

I just wish Razbams modules would takeoff like the F 16, F 18, L 39, etc.

Aircraft are different and need different handling, that's why there are special manuals (or POH) for every one of them. If every aircraft took off the same way the simulation would be wrong and unrealistic! If you have general problems with many modules post it either in each module's subforum or in general DCS bugs: https://forum.dcs.world/forum/474-general-bugs/ but it seems the problem is between keyboard and chair. There is nothing scripted in PFM/EFM.

[River]

54 minutes ago, draconus said:

Aircraft are different and need different handling, that's why there are special manuals (or POH) for every one of them. If every aircraft took off the same way the simulation would be wrong and unrealistic! If you have general problems with many modules post it either in each module's subforum or in general DCS bugs: https://forum.dcs.world/forum/474-general-bugs/ but it seems the problem is between keyboard and chair. There is nothing scripted in PFM/EFM.

Aircraft are different and need different handling ? Well thanks for that hint.

POH for every single one of them ? Who would have guessed.

And they take off in different ways ? I can't believe it.

I don't have general problems with MANY aircraft in DCS, I am pointing out the F 15 acts the same weird way on takeoff like the Harrier, the Mirage 2000 and the Mig 21. You may not like it, fine.

That you pulled that keyboard and chair card is beyond bad. I know by now you are the elite, anymore aviation secrets to share ? 

[Holbeach]

@River

If you use the correct speed for weight T/O, rotate aft stick for 1 second to 12 degrees, with a little practice you should have no pitch problems at take off.

..

[shagrat]

vor einer Stunde schrieb River:

I don't have general problems with MANY aircraft in DCS, I am pointing out the F 15 acts the same weird way on takeoff like the Harrier, the Mirage 2000 and the Mig 21.

...so you may have general problems with following individual procedures for specific planes?

Comparing the weird take off of an AV-8B Harrier to the take off with an F-15E, or a delta wing, Mirage2000 and MiG-21 sounds definitely weird, as the flight characteristics of not one of these airplanes are really "a match".

 

vor 3 Minuten schrieb Holbeach:

@River

If you use the correct speed for weight T/O, rotate aft stick for 1 second to 12 degrees, with a little practice you should have no pitch problems at take off.

..

^this