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Landing question


pfrabott

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Hello, I am trying to land from a high altitude (I do this from a semi-hover, that is, a hover that still has me going less then 3 knots), I do this if I miss the approach due to being to high. When I start to decend above the runway and I get around 40 feet from the ground it seems that I start getting sucked in toward the ground and my decent rate increases. This causes my to crash, or damage the helicopter. I tend to see this more if I am decending below 40 feet at 5VS or more. I'm assuming this is a physics thing but can someone explain it better to me? It might help me land safely if I understand what is actually going on.

 

Also if I get before 40 feet and the rotors are not parallel the the ground, but say at an angle more then 15 degrees it causes the helocopter to become very unstable, even worse then if it's parellel.

 

Thanks for any help.

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Vortex Ring State

 

Think of it as the equivalent of a Fixed-Wing Stall :)

 

Edit: Sniped by Erdem :)

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Ok. So I need to adjust my VS to be less then 5 to correct this, correct?

 

In order to correct it you need to push hard forward on the Cyclic and Pray you have enough altitude..........;)

 

In order to prevent it, watch your VVI very carefully and maintain a descent rate of 3m/s or less :)

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Right,

 

but to get out you need to gain horizontal velocity, not just apply more power. :smartass:

 

To avoid this situation don'n exeed 5 VS when going slow.

 

I just read that on the Wikipedia page.

 

Now let me ask this. Because in the first campaign mission where they take you "around the block" I had the same problem when going over the mountains only it caused me to start turning and caused this downwash or VRS to occur. What altitude from ground level should I be at during normal flight?

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....Because in the first campaign mission where they take you "around the block" I had the same problem when going over the mountains only it caused me to start turning and caused this downwash or VRS to accur. What altitude from ground level should I be at during normal flight?

 

Service Ceiling of the Kamov is 18 000ft or thereabouts. The problem that you have in the Mountains is of the 'User-Error' variety :)

 

Ensure that your Anti-Icing systems are turned on. Also ensure that your climb-rate is within normal parameters, ie maintain an optimum Ascent rate of approx 130km/h, climbing at about 5-10 m/s and you should have no bother. Any further problems, post a track and we'll be able to help you further.

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Service Ceiling of the Kamov is 18 000ft or thereabouts. The problem that you have in the Mountains is of the 'User-Error' variety :)

 

Ensure that your Anti-Icing systems are turned on. Also ensure that your climb-rate is within normal parameters, ie maintain an optimum Ascent rate of approx 130km/h, climbing at about 5-10 m/s and you should have no bother. Any further problems, post a track and we'll be able to help you further.

 

Sounds good. Thanks for your guys' help!

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Also, it was incorrectly stated here that you need to apply power to get out of VRS. This is in fact the opposite of what you should do, increasing collective will only worsen the VRS condition. Instead, your immediate reaction to entering VRS should be to bottom out the collective, and kick forward the cyclic to get some immediate horizontal velocity.

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I just read that on the Wikipedia page.

 

Now let me ask this. Because in the first campaign mission where they take you "around the block" I had the same problem when going over the mountains only it caused me to start turning and caused this downwash or VRS to occur. What altitude from ground level should I be at during normal flight?

 

AFAIK proximity to the ground should not in any way make you more susceptible to VRS. If you experienced flight issues from flying too low, then the cause is not VRS. I'd wager that your problems resulted from one of the following:

  • dust intake (doubtful)
  • engine icing (not related to being close to the ground, but could be an issue)
  • autopilot failure/shutoff due to loss of electrical power or exit from normal flight parameters (very common for less experienced pilots)

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Also, it was incorrectly stated here that you need to apply power to get out of VRS. This is in fact the opposite of what you should do, increasing collective will only worsen the VRS condition. Instead, your immediate reaction to entering VRS should be to bottom out the collective, and kick forward the cyclic to get some immediate horizontal velocity.

 

Yeah, I got that from Wikipedia. It too agrees that horizontal movement is the way out of the VRS.

 

I was able to complete the first mission on the campaign, Although I almost landed off the pad.

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AFAIK proximity to the ground should not in any way make you more susceptible to VRS. If you experienced flight issues from flying too low, then the cause is not VRS. I'd wager that your problems resulted from one of the following:

  • dust intake (doubtful)
  • engine icing (not related to being close to the ground, but could be an issue)
  • autopilot failure/shutoff due to loss of electrical power or exit from normal flight parameters (very common for less experienced pilots)

 

I still don't know how to use the autopilot. lol. Anyway, I replayed the track from my flight (the one I crashed onto the mountain on) what I didn't see was a warning light on the warning panel that stated overspeed. I was going over 280 knots on the HUD (why is the HUD different then the steam gauge? They work on different sensors or something?)

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The HUD gives you the ground speed, while the steam gauge indicates air speed. So, on a windless day the two will ideally read the same. Given headwind or tailwind, however, the steam gauge is what you should use for managing flight parameters, while the ground speed indicator on the HUD is useful for hovering, landing, etc.

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The HUD gives you the ground speed, while the steam gauge indicates air speed. So, on a windless day the two will ideally read the same. Given headwind or tailwind, however, the steam gauge is what you should use for managing flight parameters, while the ground speed indicator on the HUD is useful for hovering, landing, etc.

 

So, the HUD speed is similar to the GPS-AAS reading in an airplane and the steam gauge is exactly the same as the steam gauge in an airplane.. got it. thanks.

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The HUD gives you the ground speed, while the steam gauge indicates air speed. So, on a windless day the two will ideally read the same. Given headwind or tailwind, however, the steam gauge is what you should use for managing flight parameters, while the ground speed indicator on the HUD is useful for hovering, landing, etc.

 

 

indicated airspeed will be lower than ground speed the higher you go, due to the falling density of the air ..

 

sure, at the heights that a combat helo typically flies at, that's not normally a huge issue, but it's still a factor at a couple of thousand feet.

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Yeah, do NOT apply more collective when you're in VRS. That will actually cause you to sink faster.

 

The only way to get out of a VRS state is to move horizontally. It doesn't have to be forward. Any direction will do. I've recovered backwards, diagonally, sideways, etc. The important thing is to get away from the descending column of air generated by your rotor blades. Even a short distance (one rotor diameter) should do the trick and allow you to recover.

 

You'll soon recognize when your helo is about to enter VRS. I used to be very nervous about it but now it's not a problem. If your airspeed is lower than, say, 20 or 30 knots, pay special to Vertical Speed Indicator. If the VSI is reading a descent rate greater than 300, watch out. Arrest that descent unless you've got plenty of forward airspeed.

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