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stable hover help


DayGlow

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Really trying to get a feel for this airframe, but for the life of me, I'm having trouble with the vertical takeoff tutorial.

 

It says to avoid any forward or back pressure on the stick to avoid hot gasses into the engine, but as soon as I'm weight off of wheels the nose dips forward and I have 10+ knots of forward airspeed. If I put backpressure on the stick as I take off, I'm unstable AF

 

After awhile I'm to the point of bobbing up and down, but I can never get stationary in all 3 axis

"It takes a big man to admit he is wrong...I'm not a big man" Chevy Chase, Fletch Lives

 

5800X3D - 64gb ram - RTX3080 - Windows 11

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Well, the obvious and annoying answer is that it takes hours and hours of practice to learn VTOL.

 

But more specifically and more helpfully, I'd ask what your nozzle angle is at takeoff and if you are trimming back 2 deg before lifting (this would help counter the immediate nose dip / forward motion).

 

I understand the instructions and written procedure, but I'll add that I'm probably doing control inputs immediately at liftoff and have never experienced hot gas ingestion (is this modeled? I have no idea).

 

Lastly, try adding power more slowly as you lift if your goal is to get into a stable hover (as opposed to immediate launch into forward flight).

 

Extra-lastly ;) consider a joystick extension or a steeper curve on your stick axes to make small inputs easier when close to center. This may help avoid over corrections and keep you 'ahead of the aircraft'.

 

Practice practice practice! It's worth it when you reach the point that you can tool around, floating between buildings and dancing around stuff.

Good luck and keep going.

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Trim back? The tutorial states 2 down stab trim. Nozzles are at 82. I've tried neutral and the directed down stab trim, I'll have to try trimming against the direction.

 

I have a Virpil base with a 6cm extension, all don't think it's that.

"It takes a big man to admit he is wrong...I'm not a big man" Chevy Chase, Fletch Lives

 

5800X3D - 64gb ram - RTX3080 - Windows 11

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Understood.

If trimming alone doesn't help, I'd say adjust nozzles to get a clean no-dip lift, and work from there. Try 84?

i7 9700k | GTX 1080 | 32 gb | X55 + ProFlight pedals | TrackIR | Win10

 

Caucasus | Nevada | Persian Gulf | Normandy | Channel | Syria

A-10C | AV-8B | F/A-18C | F-16C | UH-1H | SA342 | Mi8 | Ka50 | FC3 | CA | SC | Kiowa

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DayGlow I agree with your confusion regarding trim.

I know nothing about the real world procedures or handling of this aircraft but it's perhaps possible the instruction to trim "down" is a mistake or misinterpretation. But even then, trimming "back" by a full 2 degrees, in my short experience, would seem excessive.

What has worked for me is to trim back by just a couple of 'clicks' of the trim hat. (If you make the input visualisation box - whatever it is called - visible then I trim to put the little white diamond just below the centre line so the tip of the diamond touches the line, or there abouts).

 

 

A suggestion regarding the throttle: as the tutorial says, smoothly roll it all the way to max! This will likely produce quite a fast lift off so be ready to calmly reduce it again very soon after lifting off.

I find (also with helicopters) that a reasonably swift lift off is often much easier to control than a very slow one.

Slow and controlled is something that comes naturally over time. Being a little forceful (in a gentle way) can actually make things a bit easier to begin with.

 

 

(Silly example: swipe a pen quite quickly across a page and the line you draw will probably be a lot smoother and straigher than if you drag the pen very very slowly)

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It needs practise hover the AV-8B, very much like flying Helicopters.

 

 

@MeerCaT.. Good example with the pen..

 

 

Good practice are smooth, small, but determined stick and throttle inputs.

Don´t be tense, but try to stay relaxed.

 

 

The most important thing to learn, is to anticipate when You start to drift and then counter this - but be aware that reactions of the aircraft lags behinf Your input.

If it start to drift to the right - give some left input, but don´t hold it there until it starts moving to the left - thats the best (or worst) way to get into pilot induced oscilation. It´s btter to put in some input then be neutral and check reaction then add input again and re-check.

 

Once You get the feel for it, it´s actually not that hard to hover.

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I'm fairly new to the module, 12 hours time on Harrier. The best description I read was that it's like a hockey puck on ice!

 

Landing vertically is my challenge at the moment! Especially on a moving Tarawa. Pilot induced ocillation is my trouble.

 

So my advice is to alter the X/Y curves to be as gentle as possible. I've got my X55 at 38.

 

For take off I use nozzles at 84. A nozzle of 82 always produced forward velocity.

 

Same with landing, I'm experimenting with 84/88 to get a hover over the ship (15 knots)

 

But it's the lateral movement that's stumped me at present.

 

But hey, I can air to air refuel....that's a first!

 

Practice definitely makes perfect here. I think you need many hours !


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Someone correct me if I'm wrong, but I seem to recall that even in reality they "teach you a way" to hover it, then it is left to the pilot to figure out what works for them within the limitations.

 

First step: beware your gross weight. I don't know what the maximum weight for zero knot hover is, but it's quite low.

 

I loaded up 300 lbs short of MGW, and found I can only do a very slow approach at 110 kts at nozzle angle of 60 degrees.

 

I also found a nice way to balance the aircraft in vertical speed regardless of current gross weight, such that it remains controllable:

 

* Approach at e.g. 300 kts. Pull power to idle

* Nozzles to 80 degrees

* As the aircraft decelerates through 250 kts, gear down

* Decelerating through 200 kts, set VTOL flap

* As the VS starts to increase in the negative direction, increase thrust

* As the speed bleeds off, maintain a constant pitch attitude and hold altitude with power

* As soon as the power reaches max, if you still have any significant forward speed reduce nozzle angle to maintain forward speed

 

This is about as close as I can find to a safe, reliable method of flying at a controlled minimum speed in the landing configuration.

 

Once the nozzles are set up for this configuration, just pull 1 or 2% off the power at most to descend on a normal glide path to a min speed rolling landing.

 

As the aircraft gets lighter, the min speed will reduce, until you reach the maximum zero speed hovering weight.

 

As a starting point, 300 lbs below max gross results in a required forward speed of 110 kts and 60 degrees of nozzle.


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Motorola 68000 | 1 Mb | Debug port

"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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The last time I tried to do a VTOL kind of landing I just gave up since the aircraft wasn't helping me. Once I got into an initial hover I looked at the weather vane and it was pointing to my front left. Alrighty rudder a bit over to point it into the wind and get stable again. Now suddenly the weather vane is pointed clear off to the right and she wants to just spin like a freaking top while in hover. I just applied power and got into normal flight mode and landed it like a normal aircraft at that point.

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I wouldn't pay much attention to the wind vane while in hover (in fact I think we are actively advised not to chase the vane).

Once you've determined the basic wind direction (mission briefing or in-cockpit aids) while on the ground and pointed the nose in the appropriate general direction think no more about it.

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I wouldn't pay much attention to the wind vane while in hover (in fact I think we are actively advised not to chase the vane).

Once you've determined the basic wind direction (mission briefing or in-cockpit aids) while on the ground and pointed the nose in the appropriate general direction think no more about it.

 

 

Not talking about take offs as she is always WAAAY too heavy for VTOL on take off. Specifically talking about VTOL landing and a few of the vids I watched in the tutorial section specifically stated a VTOL crosswind landing could bring problems.

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Not talking about take offs as she is always WAAAY too heavy for VTOL on take off. Specifically talking about VTOL landing and a few of the vids I watched in the tutorial section specifically stated a VTOL crosswind landing could bring problems.

 

If there is wind and you want to VLAND, approach slightly downwind, and as you approach the landing spot, turn into wind before completely reducing GROUND speed to zero.

 

This makes it easier to station-keep should the wind not be what you expected.

Motorola 68000 | 1 Mb | Debug port

"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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I'm fairly new to the module, 12 hours time on Harrier. The best description I read was that it's like a hockey puck on ice!

 

Landing vertically is my challenge at the moment! Especially on a moving Tarawa. Pilot induced ocillation is my trouble.

 

So my advice is to alter the X/Y curves to be as gentle as possible. I've got my X55 at 38.

 

For take off I use nozzles at 84. A nozzle of 82 always produced forward velocity.

 

Same with landing, I'm experimenting with 84/88 to get a hover over the ship (15 knots)

 

But it's the lateral movement that's stumped me at present.

 

But hey, I can air to air refuel....that's a first!

 

Practice definitely makes perfect here. I think you need many hours !

 

Yeah I'm finding nozzles at around 84 helps with better velocity control. Still can't stable hover, but a lot less initial nose drop on lift off

"It takes a big man to admit he is wrong...I'm not a big man" Chevy Chase, Fletch Lives

 

5800X3D - 64gb ram - RTX3080 - Windows 11

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