Out of Curiousity - Rotor Brake Anyone?

[Luigi Gorgonzola]

Reading the Black Shark Flight Manual (both), I used to be a little confused by the Collective Brake. Having found some additional description of different helicopters in the web, I understand that one is supposed (if not obliged) to press the lever, thus disengaging the brake, prior to any Collective movement.

 

IRL, as far as I understand, it would be impossible to move the Collective while the brake is engaged. Is that correct?

 

Apart from that, I briefly tried it in DCS - with all four AP/AH buttons pressed - and found keeping altitude quite easier,, so I think, I'll keep this habit :)

Edited January 4, 2012 by Luigi Gorgonzola
Confused rotor and collective brake - fixed

[ZaltysZ]

Don't confuse rotor and collective brakes. Former is supposed to stop rotors from spinning while aircraft is on ground and shut down, and later is supposed to prevent unwanted movements of collective.

[Luigi Gorgonzola]

Don't confuse rotor and collective brakes. Former is supposed to stop rotors from spinning while aircraft is on ground and shut down, and later is supposed to prevent unwanted movements of collective.

Sorry, it's been obviously too early for my brain replacement device to work properly :poster_oops:

 

Of Course, I intended to refer to the Collective Brake, trying to fix this in the OP...

[Griffin]

Collective brake also commands the autopilot altitude hold. It works like trim on cyclic when Alt Hold is enabled. When you depress the brake, it will disengage the automatic control and when you release it, it will try to hold that current altitude. This mode also has only 20 % of control.

[Heli Shed]

Collective brake also commands the autopilot altitude hold. It works like trim on cyclic when Alt Hold is enabled. When you depress the brake, it will disengage the automatic control and when you release it, it will try to hold that current altitude. This mode also has only 20 % of control.

 

I taught you well young paderwon!

[AlphaOneSix]

In the real aircraft there is a friction that holds the collective lever in place so you can take your hand away from it without worrying about it moving on its own. Pressing the collective brake lever removes this friction. Also, this friction can be overcome without pressing the brake lever, a typical force requirement is in the area of 50 pounds to overcome the friction. I'm not sure what it is exactly for the Ka-50, but it's probably close to that, or less.

[Shein]

I was under the impression that pressing the trimmer with the altitude autopilot channel engaged was the same as selecting a new altitude to hold... is there a separate command for the collective brake?! What about with flight director turned on, will it still hold altitude?

[AlphaOneSix]

The trimmer on the cyclic is for the roll, pitch, and heading channels (cyclic and pedals). The collective brake is essentially the trimmer for the altitude channel. There is a separate command for the collective brake. I think it's the F key by default, but I'm not positive on that. It will be labeled "Collective brake" when modifying the controls.

[Luigi Gorgonzola]

In the real aircraft there is a friction that holds the collective lever in place so you can take your hand away from it without worrying about it moving on its own. Pressing the collective brake lever removes this friction. Also, this friction can be overcome without pressing the brake lever, a typical force requirement is in the area of 50 pounds to overcome the friction. I'm not sure what it is exactly for the Ka-50, but it's probably close to that, or less.

 

So it's "just" friction? I remember reading of similar brakes in different helicopters when browsing the web for more information, but as it didn't seem to be something common to all helicopters, my confusion started. Some have it, others don't?

 

Anywa, thank you very much for your explanation! :)

 

Oh, and by the way - yes, it's "F".

Edited January 5, 2012 by Luigi Gorgonzola
added content ;)

[Shein]

Whoa. I gotta try this... thanks!

[AlphaOneSix]

So it's "just" friction? I remember reading of similar brakes in different helicopters when browsing the web for more information, but as it didn't seem to be something common to all helicopters, my confusion started. Some have it, others don't?

 

Depends on the helicopter, really, but all the ones I've worked on have some kind of friction setting for the collective, either through some kind of collar that you tighten, causing actual friction, or some kind of trim servo/magnetic brake that uses an electromagnetic clutch to hold the control in place.

 

Obviously, you can't fly with both hands all the time. At some point, you have to use one of your hands to flip switches or change frequencies or whatever. Pilots typically always have one hand on the cyclic no matter what, so if they use their right hand for something, their left hand moves from collective to the cyclic. If they need to use their left hand for something, well then they just take it off the collective. So the collective needs some mechanism to prevent it from creeping up or down if you momentarily remove your hand from it.

[tusler]

If you are familiar with motorcycles at all. The collective brake works on the same principle as the manual throttle friction lock.

[Luigi Gorgonzola]

Depends on the helicopter, really, but all the ones I've worked on have some kind of friction setting for the collective, either through some kind of collar that you tighten, causing actual friction, or some kind of trim servo/magnetic brake that uses an electromagnetic clutch to hold the control in place.

 

Obviously, you can't fly with both hands all the time. At some point, you have to use one of your hands to flip switches or change frequencies or whatever. Pilots typically always have one hand on the cyclic no matter what, so if they use their right hand for something, their left hand moves from collective to the cyclic. If they need to use their left hand for something, well then they just take it off the collective. So the collective needs some mechanism to prevent it from creeping up or down if you momentarily remove your hand from it.

 

Ah, I used to expect the collective to keep its current position anyway. Reading your explanation, I understand that without the brake or the friction, the collective would return to its down position as soon as the pilot takes off his hand. That's interesting, thanks a lot :)

 

If you are familiar with motorcycles at all. The collective brake works on the same principle as the manual throttle friction lock.

 

What kind of bike do you own? Neither of my bikes throttle grips ever kept its position when I took off my hand. All returned to their "closed" position, some faster, some slower, depending on the amount of dirt collected and applied during earlier rides ;)

 

I know of some aftermarket accessories that keep your throttle grip at a fixed position (either by friction or by a pin locking the grip), but I wouldn't like to see any of these on my bike (don't even know if they're legal in my country at all).

[Devrim]

...if they use their right hand for something, their left hand moves from collective to the cyclic. If they need to use their left hand for something, well then they just take it off the collective. So the collective needs some mechanism to prevent it from creeping up or down if you momentarily remove your hand from it.

Actually, I'm still confused about "usage" of collective brake. I didn't want to open a new thread.

 

So, I want to ask some:

 

1) I see that, I press F (and depress), then collective brake switch goes up and down. Is that means it's engaged? Or should I press F continuously? :noexpression:

 

2) I must say I'm flying with Saitek X52Pro. With X52, do I have to use collective brake? You know, X52's collective stays where I left it.

 

3) For example, in 250 meters altitude with auto-hover, sometimes aircraft doesn't maintain it's altitute. It's increasing or decreasing. And this is annoying. Is "using collective brake" precisie solution in these situations?

 

When I engage collective brake (and A.P. ALT-HOLD on), the orange arrow of ADI (or HSI? not possitive) moves (up/down). But I can't see any altitude stability.

 

I think I'm really stil missng something.

[Luigi Gorgonzola]

Actually, I'm still confused about "usage" of collective brake. I didn't want to open a new thread.

 

So, I want to ask some:

 

1) I see that, I press F (and depress), then collective brake switch goes up and down. Is that means it's engaged? Or should I press F continuously? :noexpression:

 

Continuously whiile changing altitude, as far as I understand the concept.

 

2) I must say I'm flying with Saitek X52Pro. With X52, do I have to use collective brake? You know, X52's collective stays where I left it.

 

See AlphaOneSix' earlier explanation. IRL as well as in DCS there seems to be no "must" in using the collective brake, technically spoken. Hence, you may safely omit it. I still may be wrong, though.

 

However, and this is what I actually do, if you want to enjoy all of the AP channels, you always should use the collective brake. Not doing so would leave you dealing with the AP limits.

 

3) For example, in 250 meters altitude with auto-hover, sometimes aircraft doesn't maintain it's altitute. It's increasing or decreasing. And this is annoying. Is "using collective brake" precisie solution in these situations?

 

As long as you combine the collective brake with the "Altitude" AP channel, yes. One of the reasons, I use the brake :) But be aware of what type of altitude you're using, Radar or Barometric (applies more to flight than to hover)!

 

When I engage collective brake (and A.P. ALT-HOLD on), the orange arrow of ADI (or HSI? not possitive) moves (up/down). But I can't see any altitude stability.

 

I think I'm really stil missng something.

 

I just see yellow arrows...

 

There's a small yellow arrow on the right side of the ADI (the upper instrument / "virtual horizon"). This arrow displays the current deviation from the assigned altitude, so - according to your description - it is serving its purpose perfectly fine.

 

According to your description, you're trying to hover with the brake engaged. While it may work, it's probably not the best approach ;) Engaging the brake - pressing "F" - disengages the AP Altitude channel. You'd have to disengage the brake - let go the "F" key - in order to assign a new altitude value to the AP. That should do the trick.

 

Engage brake -> set/approach new altitude -> disengage the brake -> enjoy.

[Devrim]

Thank you so much Luigi Gorgonzola. I'm now at work. Evening, I'll try about your explanations. Thanks again...

[159th_Viper]

...Hence, you may safely omit it. I still may be wrong, though....

 

Quite so - have not once, never used it myself

[AlphaOneSix]

The only reason, in-game, to use the collective brake is to assign a new altitude *without* using the descent mode of the autopilot while in hover hold. When you press the "Descent" switch while in hover hold, the autopilot will hold the altitude you're at when you release the "Descent" switch, you don't have to reset it using the collective brake.

 

Here are the situations I can think of for using the collective brake swutch in-game:

 

1) You are in hover hold but you want to gain altitude. You would press and hold the collective brake switch (otherwise you would fight the autopilot inputs) adjust collective as necessary to ascend to your new desired altitude, stabilize the aircraft at the new altitude, and then release the collective brake switch to have the autopilot capture and hold the new altitude.

 

2) During cruise flight using the altitude hold mode of the autopilot (typically while also in ROUTE mode), you wish to change your desired altitude. It doesn't matter if your using radar or barometric. In this case, again, you'd press and hold the collective brake, adjust collective and stabilize at your new altitude (higher or lower, whichever) then release the collective brake switch to capture and hold the new altitude. This prevent you from having to turn off the altitude hold mode of the autopilot just to change altitude. In practice, I think most people "set it and forget it" and if they want to change altitudes, they just turn the altitude mode off altogether and maybe (or maybe not) turn it back on later.

[Luigi Gorgonzola]

1) and 2) are exactly how I use the collective brake now, plus loosing altitude as well (not really necessary as I could also use the descent mode, I know).

 

The effect of doing so - and this is, at least to me, the most important and enjoyable fact - is a smoother flight and I don't have to keep the state of the altitude channel in mind.

 

No necessity, I know, but I enjoy it. :)