TM Warthog users, is the axes blending problem a big deal?

According to a friend of my who is a Super Hornet pilot feeling two separate axis is not how it is in a real Super Hornet. If you want a realistic joystick that simulates a modern fighter the Warthogs blended axis feel is the only one you can get right now.

 

For simulating an F-16 obviously the X-55 would be better.

I assume that's directed at me. The Rhino's stick has completely separated axes of tension. One in pitch, and a second one in roll. I may have not been clear, but the picture in my last post was. A good stick like the Hornet's has separate axes of tension. That does not mean they "feel" separated. The transition between axes is still smooth. The Warthog has tension applied radially, in all directions, instead of in the two axes of control. If that does not make sense, I can clarify further, but you are wrong. The HOTAS Warthog is not a superior simulation of real flight controls, especially not for the Hornet. I think you would be surprised by the feel of a stick in a real jet, it's nothing like the Warthog! :)

Anyway, I think you've misunderstood my post and focused on one thing for the sake of the argument. I'm not claiming that Thrustmaster solution is better or it feels like a real aircraft, just pointing out that it's not such a big problem and the use of cams doesn't make the joystick automatically better (though you can build a better joystick than Thrustmaster did, that's for sure). I have Slaw rudder with damper mod and I know what a good cam can do, and what it can't.

Sorry, I only wanted to make sure it is understood that the Warthog's design is an engineering compromise, not a superior or realistic solution. I agree that it doesn't make it unusable, but I do think that it would be hard to build a cam design that did not outperform the Warthog for reasons stated. That's why I look forward to putting my Warthog grip on a VKB gimbal!

http://forums.eagle.ru/showpost.php?p=2817563&postcount=4

Accurate description of the reason engineers don't design real aircraft that way.

People seem very quick to defend what they paid 3-400 USD for. Who'd have thought? :D

I'm a professional pilot, but I choose not to name my employer on the internet. Ironically, I was discussing this a couple days ago with a friend who also happens to be a Rhino driver here in the US. I think what's really happening here is that you aren't reading my posts or understanding them.

The Super Hornet's stick is of dual-jointed construction, each joint providing movement in one axis. The two joints are not even co-located. (http://img.photobucket.com/albums/v630/Pretzel/IMGP1152.jpg) "...stick feel is provided by two feel-spring assemblies and two eddy current dampers. The feel spring assemblies provide a linear stick force versus stick displacement gradient in each axis." (A1-F18EA-NFM-200)

Two separate springs providing X and Y tension. This does not imply there is a noticeable sticking point when crossing axis center. (Unlike the incessant friction/sticktion in the Warthog's mechanism.) In fact, all it does is ensure that tension in one axis is not affected by tension in another.

With the Warthog...

...if I deflect half left-stick and then move the stick through the full pitch range, I'll have [...] inconsistent roll tension.

With a real stick, that does not happen.

Some more details on the F/A-18 FCS can be found

on page 4 of this paper.

The longitudinal and lateral mechanical components of the FCS are comprised of the following: cockpit control stick, longitudinal and lateral feel springs, longitudinal trim actuator, linkage and cables between the control stick and stabilator servo actuators, and an electromechanical ratio changer which adjusts the stick to stabilator gearing while in the mechanical backup mode. Longitudinal and lateral spring cartridges provide control stick forces to the pilot. A counter weight is provided in the longitudinal axis to counter control stick inertial forces encountered during a catapult launch.An eddy current damper is provided to add an additional lateral stick force increment as a function of lateral stick rate...

...

Design longitudinal and lateral breakout plus friction and stick force gradients are presented in table I:

Table I [table=head] Direction | Breakout (Plus Friction) [lb] | Stick Force Gradient [lb/in]

Longitudinal |

|

± 7.4

 

Lateral |

± 2.0

|

± 3.7

[/table]

± 3.0

 

The key point (as Aaron described) is that longitudinal and lateral axes are almost always loaded independently. This principle is true for the F-15. The images below are from this NASA TM.

Longitudinal Axis

The longitudinal mechanical stick force characteristics, showing trim authority and breakout force, are illustrated in figure 17. The control-stick-to-stabilator gearing ratio is determined by the pitch ratio adjust device (PRAD) , which is scheduled as a function of dynamic pressure and Mach number. The pitch trim compensator (PTC) supplies the series trim to the longitudinal control system by summing its position with the pilot input. This function compensates for changes in trim caused by changes in speed, flap deflection, speed brake deflection, and

store separation.

Pitch command augmentation blends airplane normal acceleration and washed- out pitch rate to form a C*feedback system. The longitudinal command system

feel characteristics are depicted in figure 18. The maximum pitch CAS authority

is ±10° of stabilator; however, the variable pitch CASlimiter reduces this authority when mechanical stabilator commands exceed 5° and -19°. Gunsight tracking runs by both AFFTC and DFRC pilots showed this system to be extremely sensitive

with CAS on.

Lateral Axis

The lateral mechanical stick force characteristics, showing trim authority and breakout force, are illustrated in figure 19. Lateral mechanical advantage is pro- vided by the roll ratio adjust device (RRAD) and is scheduled with longitudinal collective stabilator position as shown in figure 20. The mechanical advantage is adjusted at high speeds by hydromechanical control system feedback scheduled

as a function of calibrated airspeed.

Roll command augmentation is provided through the stabilator CASseries servos according to the schedule shown in figure 21. The differential stabilator- to-stick gearing ratio is 0.3° of differential stabilator per degree of aileron deflection except where restricted by the stabilator actuator limits. Dynamic pressure and angle of attack limit schedules are incorporated into the CAS variable limiter.

 

Great diagrams! The breakout force is ergonomically necessary but sometimes a nuisance, for example in aerial refueling or formation flying. In those situations it's common technique to use forward trim and keep the stick loaded forward at all times.