One of them has kept me quite busy and I would like to put some ideas forward and hopefully engage in a discussion on this subject.
Most if not all PC based simulators will work with the common joystick. This can be a digital or analog device that translates stick displacement into an electrical signal that is passed to the gameport on the PC. The PC's gameport translates these electrical signals into a X and Y displacement value.
The simulator software will pick-up this value and thus knows the position of the joystick relative to its center position. Most simulators will directly match a control surface deflection with this value. In other words when the joystick is in its center position the elevator will be neutral. When the joystick is forward of the center the elevator is assumed to be in the "Down" position.
Every simulator program has a flight model that makes the simulated aircraft fly. The elevator deflection will have an effect on the flight model behavior.
But nobody (as far as I know) has considered the real life situation. An aircraft is not flown by stick (or yoke) displacement but mainly by applying control forces. In other words the pilot applies a certain force to the stick to make the aircraft do something. It is true that the stick also displaces but at cruise speeds that displacement is marginal.
Therefore the current method of using displacement joysticks and simulator software that links these displacements directly to control surface deflection is incorrect.
What we need for a more realistic simulation experience is a Force Joystick. No, I am not talking about a force feedback joystick here! A Force Joystick does not measure stick displacement but it measures the amount of force applied to the stick. This force is then translated into an electrical signal and send to the gameport.
The advantage of a Force Joystick is that a full deflection can require applied forces as high as experienced in real aircraft. For example a max rate turn (level turn with a bank up to 60 degrees) will require about 200N (20 KG or 44 lbs) applied control force. This varies of course per aircraft type. A force feedback joystick is never capable to apply this kind of feedback force to the stick.
Of course some control displacement on a Force Joystick is required to make it feel right but that can be achieved using some kind of rubber compression block between the stick and the load cell detecting the applied force.
Also the simulator software needs to be changed. You can appreciate that it is easy to give a full 'Up' elevator deflection in a parked aircraft as there is no airflow over the surface to force the elevator out of the main airflow. At cruising speed the situation is different and it may well be that you break something before you'd even get to full elevator deflection.
What I am trying to say here is that the force required to achieve full control surface deflection depends on the aircraft's airspeed. It is often said that "The controls feel a bit sloppy at very low airspeeds" like experienced on landing. This is because the engine and thus propeller is idle or at low power and the airspeed is as low as possible for the landing.
A good PC simulator needs to constantly recalibrate a Force Joystick to make the simulation realistic. It is the PC that can decide how much force is required for a certain maneuver without the cost of very powerful force feedback joysticks.
There is one little problem... by my knowledge nobody makes Force Joysticks. This is a pity because they would be extremely cheap to produce as the moving parts are limited and very simple. I would even dare to suggest that they would be cheaper to produce than the conventional displacement joysticks.
So... which Joystick manufacturer will start to build the ultimate in simulation. The Force Joystick! Freetrainer will have Force Joystick support for those that build their own Force Joysticks.
I have published this article because I would like to engage in a discussion about this concept and see if it can be developed further. Please do email me.
Paul van Dinther
dinther@geocities.com
FreeTrainer Forum
