Hover and low speed transitions behaviour

[markturner1960]

Hi, I have been practicing this and wanted to understand what can happen and why a bit better……..I often find the jet doing unexpected things, for example, using the rudder to pedal turn, sometimes, I can have full rudder in, but the jet stops moving gradually, then if you slightly roll or descend, it will quickly move, other times , you are descending slowly and then the sink rate will suddenly change. 
 

I understand the basic principles, but it’s these sort of things that I am having trouble working out what causes them etc….

 

Any tips or in-depth tutorials etc anyone can point me to?

The jet seems a lot more tricky to handle in this flight regime than it looks !

Edited June 26, 2022 by markturner1960

[Mars Exulte]

I used to primary the Harrier.

On 6/26/2022 at 1:47 AM, markturner1960 said:

Hi, I have been practicing this and wanted to understand what can happen and why a bit better……..I often find the jet doing unexpected things, for example, using the rudder to pedal turn, sometimes, I can have full rudder in, but the jet stops moving gradually, then if you slightly roll or descend, it will quickly move

  During hover, maneuvers are performed with RCS thrusters on the nose, tail, and wingtips. They don't have much power, so if you're moving very fast, in bad weather, roll too far, etc, they simply don't have thrust to counter it. If you mean during forward flight, the Harrier's wingshape and profile give it some unique handling characteristics compared to the more typical fighter layout.

On 6/26/2022 at 1:47 AM, markturner1960 said:

other times , you are descending slowly and then the sink rate will suddenly change. 

  This can be dependent on specifics. Very close to the ground or carrier deck, you get into ground effect, which is basically the blast off your engines billowing back up into your aircraft. There are several important things to consider :

#1 Face into the wind whenever practical, otherwise you'll intake hot exhaust gases and lose power. Also, disregarding THAT, windspeed contributes to lift or substracts from it. If you are moving forward at 40kts, with a 20kt headwind, your lift is equivalent to 60kts over the wing. If you turn around, now you subtract that 20kts, leaving you with equivalent of 20kts worth of lift. That's a pretty big difference, and will definitely affect your sink/climb rate.

#2 When hovering, always have your gear deployed. Those vanes on the belly are intended to catch the ground effect. When you deploy your gear, look closely and you'll see additional vanes deploy to further enhance the effect. If I remember correctly, it's a difference equivalent to about 1000-1100lbs of thrust, which is pretty significant. If you don't have your gear deployed, or raise them while still hovering, you are missing a substantial amount of boost.

#3 Do not hover very high off the ground. Ground effect reaches it's peak around 20ft agl, and tapers off very quickly above that. This leads to #4

#4 When performing VTOL on a ship, be very aware of the sides. The ship itself is relatively tall, and if you slip over the edge, you just went from 20ft agl to 100+ and lost the ground effect boost mentioned previously, very possibly causing you to start dropping.

On 6/26/2022 at 1:47 AM, markturner1960 said:

The jet seems a lot more tricky to handle in this flight regime than it looks !

  It is and it isn't. You have to be aware of what your doing and what the environment is. Something helpful : on your HSI it also displays windspeed and direction

  Another common thing is fiddling with the thrust nozzles during a hover. I used to be an advocate of trying to hold the nose level while adjusting the nozzles.  Don't. Just... don't. It greatly increases the mental and physical workload and serves absolutely no beneficial purpose. Set the goddamn nozzles (usually this will be 82 degrees with nose level) and then fly it like a helicopter as necessary. If windspeeds are really high or the ship is moving particularly fast, you may need to adjust them for slightly more forward thrust, but regardless, once set, don't touch them again.

  Lastly, when touching down, don't engage in foreplay, just get it over with. Ground effect gets stronger the lower you get, and you don't want to settle with power or you'll find yourself rolling around the deck or drifting all over six foot off the ground. Establish a stable hover in full ground effect 20ish ft off the ground, chop your throttle back to begin descending smoothly, and in the last split second before touchdown cut throttle completely and apply full brakes. You should plunk down firmly, with idle engines and brakes. Watch the professionals in RL, it often bounces slightly when they set it down = firm landing.

[markturner1960]

Thank you!