Now hear this
Graviman
If you have any specific questions that you feel are not answered in my lecture on the site you quoted then send me a PM and I will do my best to help.
I see you dabble with the R22. Take my word for it if you can hover one of those then (from a stick and rudder point of view) you would find the Harrier a doddle to hold steady in a hover.
Why? Because as you know when you move any helicopter control it is necessary to make an adjustment in another. EG Lift the collective to gain a bit of height and the rotor tries to slow down so you open the throttle to compensate which then requires a different rudder input to match the new torque. When you open the throttle in the hover in a Harrier it just goes up. Nothing else happens. Similarly use of any of the reaction controls does not make the RPM sag as waving the cyclic can in a chopper. There are some aspects of the Harrier which might seem harder than flying an R22 but hovering is NOT one of them.
Indeed I have been known to suggest to overconfident fixed wing pilots who think they are little aces (regarding their stick and rudder skills) that they go and try to hover an R22 – they soon find they are not top of the heap after all.
Nick
I am quite sure you have your tongue in your cheek and fully understand what you are posting about. The trouble is many other people will not and could go away with the wrong idea.
You have correctly suggested that the means used to support a Harrier in the hover (jet lift) is less efficient than a wing (Blackhawk rotor) at producing the required force. The problem with such a simple (even patronising) comparison is that the Harrier is not intended to do a job in the hover (airshows excepted!) but merely to spend 30 secs in getting from flying on its wings to arriving vertically on a small bit of surface – with all the advantages that flow from that with regard to operating site flexibility.
As to efficiency your readers might like to know that a Harrier uses less fuel in doing a VTO and accelerating to cruise speed on heading towards the target than if it takes off conventionally from a runway. The only exception to this is when the runway is pointing along the track you need and the aircraft is towed from dispersal to the runway before start up.
For the general readers I should perhaps finish by saying that a heavier than air device needs to generate the force needed to hover by grabbing a mass of air and accelerating it downwards such that the product of mass X velocity equals the weight of the hovering device. A Harrier grabs a (relatively) small mass of air and gives it a pretty big velocity a Blackhawk rotor grabs a (relatively) huge mass of air and so only needs to give it a relatively small velocity to get the same end result
The lower the velocity used the greater the efficiency of the system.
In that context the prop rotor on a tilt rotor machine grabs rather less air and so has to give it a higher velocity which is going in the less efficient direction.
The Boeing offering for the JSF competition used Harrier direct lift principles (very simple from the mechanical complexity standpoint but poor efficiency) the Lockheed used a combination of jet lift and fan lift (more efficient but more complicated) In the end given the reliability of modern complex systems (better design, better materials, better lubricants, better etc etc) the efficiency advantage of the Lockheed system won the day. The better efficiency due to the lower V used by the fan part of the system enabled the same basic powerplant (as used by Boeing and Lockheed) to hover an aeroplane that was over 20% heavier. A bit more than a marginal advantage.