Question on the use of the collective brake

[sobe]

I am a little confused on the use of the collective brake (CB).

Do you use the CB only when you also use the altitude hold?

If you want to change altitude, do you "release" the CB, change altitude and then put the CB back on?

I would appreciate if some one would just explain how to use the CB in plain English.

 

Thanks:helpsmilie:

[Boulund]

In real life the collective brake is there to prevent unwanted slipping of the collective. It's as such always activated when you do not move the collective.

Example:

I'm flying straight ahead - collective break active, even if I have my hand on the collective.

Leveling out and adjusting collective - release the break, move collective, reapply the brake.

 

Easy as that. It does not really have a "proper" use for us simmers I guess.

[EtherealN]

Well, unless the throttle lever on your stick is extra wobbly. :P

[nemises]

Its proper use in the sim is to set the goal altitude for the alititude hold channel.

 

If you are in altitude hold mode, and wish to increase or decrease altitude, you should press and hold the collective brake, then ascend/descend, then release it (think of it a bit like the trimmer for altitude)..thats it's only real function in the sim...IRL of course, it is also a physical barrier to moving the collective, and would allways be held in (ie. disengaged) when moving the collective...

[Boulund]

Its proper use in the sim is to set the goal altitude for the alititude hold channel.

 

If you are in altitude hold mode, and wish to increase or decrease altitude, you should press and hold the collective brake, then ascend/descend, then release it (think of it a bit like the trimmer for altitude)..thats it's only real function in the sim...IRL of course, it is also a physical barrier to moving the collective, and would allways be held in (ie. disengaged) when moving the collective...

 

aah!

Wonderful, I had no idea you could set a desired altitude for the altitude hold mode. I just thought it automagically entered the current altitude as the preferred and that you turned it off whenever you wanted to change altitude. I've never really found a use for altitude hold unless when autohovering, but I very seldom do that and always find it a bit awkward to always have to turn it off after leaving autohover.

[72AG_terror]

aah!

Wonderful, I had no idea you could set a desired altitude for the altitude hold mode. I just thought it automagically entered the current altitude as the preferred and that you turned it off whenever you wanted to change altitude. I've never really found a use for altitude hold unless when autohovering, but I very seldom do that and always find it a bit awkward to always have to turn it off after leaving autohover.

 

Don't forget that autopilot only have +/- 20% range of the engine power to maintain set altitude, so if you are in a break turn or flying into a mountain at 250 km/h... don't count on it too much or you will crash, pull the collective yourself in situations where radical changes in alt are possible. Also, don't forget that there is a switch of what altitude you want to hold - radar or barometric.

 

[next section is all AFAIR]

The other RL vs. DCS issue is much trickier. Imagine you have alt hold enabled. In RL to move the collective you must disengage the CB. So what happens is - you release the collective lever AND simultaneously disengage altitude holding by autopilot. When you let go on the lever - you engage AP AND set a new alt to hold for it.

In DCS it is possible to move collective WITHOUT disengaging CB (I guess 80% of virtual pilots do this). So if you have alt hold channel enabled then AP is still working and working against your movement of collective lever. And so if you, say, lowered your collective by 60%, you would, in fact, have the AP fighting against you with its 20%, so you will have 60% - 20% = 40% as it tries to hold the old alt. If you don't pay attention to it altitude dynamics of the chopper can be rather unpredictable, especially in NOE flight. :)

Edited August 24, 2009 by 72AG_terror

[PhoenixBvo]

Interesting issue you pointed out there, 72AG_terror. It would be more realistic (and easier) to have some additional functionality for the CB:

 

For those of us who use a cougar, maybe its possible to program it to automatically disengage the Collective Break when you move your throttle axis (set to collective in-game of course) and then re-engage it shortly afterwards.

 

Even better yet, is it possible to program this in some .lua file?

 

Anyone knows how to do this or if its possible at all? I'll take a look at it myself as well.

[159th_Falcon]

Don't forget that autopilot only have +/- 20% range of the engine power to maintain set altitude, so if you are in a break turn or flying into a mountain at 250 km/h... don't count on it too much or you will crash, pull the collective yourself in situations where radical changes in alt are possible. Also, don't forget that there is a switch of what altitude you want to hold - radar or barometric.

 

[next section is all AFAIR]

The other RL vs. DCS issue is much trickier. Imagine you have alt hold enabled. In RL to move the collective you must disengage the CB. So what happens is - you release the collective lever AND simultaneously disengage altitude holding by autopilot. When you let go on the lever - you engage AP AND set a new alt to hold for it.

In DCS it is possible to move collective WITHOUT disengaging CB (I guess 80% of virtual pilots do this). So if you have alt hold channel enabled then AP is still working and working against your movement of collective lever. And so if you, say, lowered your collective by 60%, you would, in fact, have the AP fighting against you with its 20%, so you will have 60% - 20% = 40% as it tries to hold the old alt. If you don't pay attention to it altitude dynamics of the chopper can be rather unpredictable, especially in NOE flight. :)

 

I have no experience on the KA-50 Blackshark but i do have some experience maintaining the following types of Helicopters;

Sikorsky S61N

Sikorsky S76B

Augusta Westland AW139

Eurocopter EC155B1

For all of the above (except the S61N) im sure the autopilot disengages itself at a certain degree of Pilot input, hence prefenting the situation of the AP fighting the Pilots inputs. And i think it isn't different for the KA-50.

 

Ofcourse i dont know 72AG_terror his background nor where he did get his information from so he could be correct

 

(btw, the KA-50 doesnt really have an AP, just an Auto Hover function, it does have an stabilisation system though, like most helicopters have)

[PhoenixBvo]

(btw, the KA-50 doesnt really have an AP, just an Auto Hover function, it does have an stabilisation system though, like most helicopters have)

 

What would you call the route following mode then? That most certainly is an automatic flight mode capable of controlling all 6 degrees of freedom and steering along a heading or course line. You should try disengaging the FD (flight director) and engaging route following (ROUTE-DESCENT selector on the collective). Assuming you have the stabilizer modes switched on, this will put the aircraft in fully automatic flight mode and let it fly the waypoint route if you have a waypoint selected in the PVI-800.

 

Concerning the AP function when changing the collective, I'm not sure whether it temporarily disengages, would be nice if someone from ED could clarify that...

[AlphaOneSix]

If you have the altitude hold mode of the autopilot engaged, then pressing the collective brake release also disengages the altitude hold function until you again re-engage the brake. If all you're doing is moving the collective without the using the brake release, then that does not disable the altitude hold function, and the autopilot will use its authority to return you to your previous altitude.

[PhoenixBvo]

Thanks for that AlphaOneSix. It does mean a lot of people (including me until now) are doing this wrong. The Altitude hold mode should be disengaged when one moves the collective. Of course this can be done manually using the Collective Break, but I don't have a nice collective grip with convenient break release handle, so I'd like to set things up such that the CB is automatically pressed when you move the collective.

 

In the foxy programming software (for the cougar), this is not so nicely possible, as it doesn't give access to the raw analogue axes outputs. Having access to the current axis value and a clock, one could program something like (kinda C-pseudo code):

 

if (abs(axis_value - axis_value_previous) > threshold)

{

press CB;

t = current_time;

} else if (current_time - t > delay & CB == pressed)

{

release CB;

}

 

Just run in a loop and we wouldn't have to worry about pressing CB ourselves anymore...

 

Anyone knows where to implement functionality like this?

[nemises]

..or assign a button to it on your hotas....

[PhoenixBvo]

Yes I have that as well of course. But as I said, it's not such a nice lever in a convenient position on the collective grip...

The question is, whether it is more realistic to require people to press a button each time they change collective position, or to have the break release automatically. After all, in the real thing it also goes almost automatically: When you grip the collective, you press the break lever in the same movement.

[nemises]

very true, however, you're only ever pressing it if the altitude hold mode is also on, which for me is only maybe 40% of the time?..

I see your point though ... as it's essentially automatic in the real thing etc...

 

Don't know about scripting for button presses based on axis variance though