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Joystick "at rest"

Controlling your aircraft, using the autopilot etc.

Re: Joystick "at rest"

Postby D-EKEW » Sat Aug 26, 2017 4:38 pm

Hi Thorsten,

You are right, for the airplane it makes no sense.
But for the pilot and his/her feel of the aircraft it is absolutely essential. The pilot can feel what is happening, if he pulls up or makes a corner. Very hard to explain to a non-pilot (or even to a pilot as this is so essential that it is almost an unconscious thing). This is also what I try to bring to this simulator because this aircraft feeling is completely missing and in my personal opinion it is the most important thing. It determines if an aircraft is flyable at all. It determines if the aircraft is easy to fly. The proper adjustment of the stick forces (also against each other, so pitch and roll forces) is one of the most difficult things in aircraft design.
In effect it is so essential this 'feel' (or in case of 'fly by wire' the 'artificial feel' as it is called) is required by the civil authorities. There is are requirements for the magnitude of pilot force, the stick-force-per-g and also the rise of the stick force (over airspeed). This also has to do with longitudinal stability, as the stick force direction change due to airspeed is 1:1 linked to it.
Civil aircraft (so including fly by wire aircraft) must have this. Airbus for instance tries to make this feel the same for all their aircraft, so that the pilot training for one airbus type to the other is minimal.
Military aircraft of course do not fall under the civil authorities and basically can do what they want. An F16 is a longitudinal unstable aircraft (except when supersonic as the aft shift of the wing aerodynamic center moves the neutral point aft of the CoG and thus makes it stable).

D-ECHO,
The calculations I used are implemented in JSB-sim. You can find them in the extra500 folder: extra500-flight-control.xml
The basics are not very complicated and I think there are some comments for what is what. For your aircraft to find out what the hinge moment coefficients are will however be very difficult. So unless you know exactly what you are doing, you have a really good understanding of flight physics and you have good data for your aircraft, I would refrain from using our code.

Cheers,

Eric
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Re: Joystick "at rest"

Postby LearningToFly » Sat Aug 26, 2017 4:55 pm

Presumably (?) before I attempt to land, I should remove whatever trim I was using to fly "hands free"?
If so, how do I do that - the "5" doesn't seem to reset the trim.
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Re: Joystick "at rest"

Postby D-EKEW » Sat Aug 26, 2017 4:59 pm

In the extra500, both for take-off and landing trim to Neutral. The indication is next to the trim wheel in the center console. Use the mouse wheel to change.
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Re: Joystick "at rest"

Postby Thorsten » Sat Aug 26, 2017 5:17 pm

This is also what I try to bring to this simulator because this aircraft feeling is completely missing and in my personal opinion it is the most important thing.


People differ, I guess. I've training as a glider pilot, I've flown an ASK-13 in reality and in FG, and it's 'close enough' for me in 'feel' with the mouse (apparently I rely on different sensory cues).

It'd make sense if you can drive a force-feedback stick with it, but I'm not sure I get the idea with 'deflection = force' you're applying.

In the end, it's down to hand-eye coordination. You can train that with any device, the hand just moves unconsciously after a while. Which is, I guess, why we can fly with the mouse at all.

As for important sensory cues, I mostly miss g-forces - but that is... difficult.
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Re: Joystick "at rest"

Postby Johan G » Sat Aug 26, 2017 5:23 pm

LearningToFly wrote in Sat Aug 26, 2017 4:55 pm:Presumably (?) before I attempt to land, I should remove whatever trim I was using to fly "hands free"?

When on downwind or even final approach, I would trim till the joystick is somewhat neutral.

All power and attitude changes will affect airspeed, which mainly is what you actually trim for.
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Re: Joystick "at rest"

Postby D-EKEW » Sat Aug 26, 2017 6:20 pm

Yes, I fly with the mouse and find it good enough as well.
The history is that some users using yokes were complaining about the too high sensibility of the yoke. This is no surprise. The extra500 yoke has around 500mm of travel. It needs it especially for for full flaps. If you map the 500mm to a joystick you have a problem as its travel is very limited and you will get a very sensitive control.
But then on this aircraft, the full travel at a certain trimmed state is never available. The forces are just too high. So I thought, what are you modulating? The position of the stick/yoke? No. The pilot does not care about its position. He/she relies on sensory cues as you said and pulls or pushes. He/she feels the elevator hinge moment, modulates the stick force and can make very accurate control inputs. So as most joysticks have a neutral position in the middle this concept would actually very crudely mimic the force feel. It was actually very easy to do because the hinge moment model was already there for autopilot autotrim.
So the advantage is that with a joystick, you can fly hands off and can make much more accurate control inputs. And the simulation is a bit more realistic as you really have to trim as much as in the real aircraft. For mouse-flyers it is much less relevant. And probably for sail-planes, where the stick forces are probably very small anyway, also not really interesting.

Cheers,

Eric
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Re: Joystick "at rest"

Postby wkitty42 » Sat Aug 26, 2017 6:24 pm

LearningToFly wrote in Sat Aug 26, 2017 4:55 pm:Presumably (?) before I attempt to land, I should remove whatever trim I was using to fly "hands free"?
If so, how do I do that - the "5" doesn't seem to reset the trim.

speaking in general: i always count the number of times i've hit the 7 or 1 so that i can hit the other one the same number of times to reset trim to zero... another option, though, is to use the F11 autopilot, select 0 pitch and then enable the altitude part of the AP ('X' at top of right hand pane)... i leave it on for a few seconds to allow it to adjust the pitch and trim to zero and then i turn it off... it may not work for all aircraft, though...
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