Why does the Harrier lean so much while in hover or near hover, due to RCS?

[DmitriKozlowsky]

When in hover or near hover (10 knt fwd speed), why does Harrier lean so much in direction of stick deflection. Isn't RCS becomes primary control, instead of flight surfaces in that regime?

Stick fwd (firing rear facing RCS puffer) for fwd flight.

Stick bkw (firing front facing puffer) to slow down

Stick right (firing left puffer) for right displacement

Stick left (firing right puffer) for left displacement

Pedals for nose perihuete.

 

But right now stick to side starts leaning the aircraft as in airborne flight, and keeps on increasing bank angle.

Stick fwd/back increases or decreases pitch , like in airborne flight.

[Ramsay]

The "puffers" control pitch, roll and yaw of the airframe, if the supporting column of "hover" air is tilted the aircraft drifts right, left, aft or forward.

 

The RCS "puffers" don't directly cause the translation i.e. thrust forward, aft, etc.

 

 

Edited May 31, 2020 by Ramsay

[Marsvinet]

What Ramsay said. I think you are comparing the Harriers RCS with the RCS on spacecraft. For space, it would work the way you described. But the Harrier functions more like a helicopter, where you shift where the main thrust is pointing to move, instead of actually moving the craft with the RCS.

[Fri13]

As well already explained, the harrier is balanced on your main thrust, and you move by tilting aircraft to get that thrust move you to tilted direction. And everytime you use RCS to balance, that is away from you main thrust so you need to compensate for loss of altitude.

[DmitriKozlowsky]

OK thank you.

My observation, relevant only to DCS Harrier, is that I have far more control, and how I trained myself, is to keep aircraft attitude steady at 5 deg nose pitch while gently working nozzle angle (mapped to rotary axis on X56 HOTAS) to hold aircraft at in stable fwd flight with creeping speed. Typically around 5-10 knots for confined area landing, or comfortable 50 knots approach for runway, parking area, road, linear clear flat terrain. But that is not real world technique. RW is nozzle angle is placed to 84 deg. down, and use of puffer jets to control aircraft attitude and velocity vector. This I find difficult as PIO developes, or aircraft assuming attitude tha makes no sense aerodynamically. Perhaps that is just an illusion from cockpit POV. But I have had missed approach final, to deck or parking area recovery, where my aircraft is banked at 10-15 deg, with nose up, yet the aircraft is moving or even accelerating in opposite direction, or hovering still at an angle, or not slowing down despite stick deflection with constant 84 degree nozzle down.

What works for me is keep aircraft at 5 degree pitch,wings level, nose into wind, for two point landing on simultaneous T/D of main and nose gear, while gently altering nozzle.

In real Harrier that would aviator to take hand of throttle, which is bad. My HOTAS allows me do keep my hand on throttle and nozzle angle. I suppose that can be viewed as better control then real thing. But Boeing and McDonnel Douglas, and BAE never developed such control for Harrier, thus there is probably a reason not to.