Fast jet FBW systems

[Avionker]

For the system I am familiar with (on a pointy, grey aeroplane), there is no artificial feel. Basically, the more you pull or push, the harder it gets to do so. If I recall, the relationship between stick force and displacement is linear. I think there is a damping force too. There is a breakout force to get away from centre stick.

Would that not be regarded as artificial feel then, if it feels as though the stick is actually connected to something? And surely the increasing force required to move the stick further from the centre point is simulating aerodynamic forces to some extent?

[FCSoverride]

There is no feedback to the stick. It is just a spring and damper. Is it artificial feel? I leave that to be answered by pilots.

[John Farley]

Eminence Gris

You are right of course but I was trying to use an acronym that many people are familiar with rather than one that could easily turn them off so that they learned nowt.

I guess to keep he all knowing happy I should have said:

"Q feel means the feel offered is related to IAS squared."

I must do better next time.

[Dan Winterland]

I (think) knew what you meant John.

But how does it feel in a hover when the IAS/EAS is zero?

[John Farley]

Dan

Dunno...bit like a funny dream without the mess I guess.

[Obi Offiah]

One other thing to note is that there are alpha limits for the "auto trim". So, if a pilot was to fly straight and level and let the aeroplane decelerate, the flight path would remain constant (the aeroplane would increase alpha to ensure this). Once the auto trim alpha limit is reached, the aeroplane sort of behaves like it has conventional static stability and will nose over at the trimmed alpha limit. The pilot has to pull to get more alpha.

This is why the high alpha passes witnessed at airshows, are flown with the pilot applying back pressure to the stick.