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Collective brake problem


Dr_Arrow

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Hello, I have quite a few hours in the Shark and I've read all the manuals, watched all the videos, but still have one problem with collective brake that I think is a bug or I am doing something wrong - please evaluate it. To illustrate it:

1. I am flying with 3 AP channels engaged (pitch, roll, heading)

2. I climb to the desired altitude let's say 800 m.

3. Manually stabilize the altitude with collective so the vertical speed is zero for the given forward speed.

4. Now I engage altitude AP (set to baro) and the Shark maintains the altitude (rotor pitch blades angle changes automatically) and the channel has enough authority to change the pitch.

5. Now I want to climb another 50 meters. I depress the collective brake (animated collective brake is depressed).

6. Increase the collective while still holding the brake depressed.

7. Autopilot is fighting me and is decreasing rotor blade pitch (it can be seen on the indicator that the rotor pitch at first increases a bit and then returns to previous level).

8. Shark does not climb unless I pull the collective lever beyond 20% authority of the alt AP channel (still holding the collective brake).

 

What am I doing wrong? Or what can be wrong? As I understand, with collective brake depressed AP channel should be off and I should be able to change rotor blades pitch freely. Thanks to everyone for their answers and time.

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Hello, I have quite a few hours in the Shark and I've read all the manuals, watched all the videos, but still have one problem with collective brake that I think is a bug or I am doing something wrong - please evaluate it. To illustrate it:

1. I am flying with 3 AP channels engaged (pitch, roll, heading)

2. I climb to the desired altitude let's say 800 m.

3. Manually stabilize the altitude with collective so the vertical speed is zero for the given forward speed.

4. Now I engage altitude AP (set to baro) and the Shark maintains the altitude (rotor pitch blades angle changes automatically) and the channel has enough authority to change the pitch.

5. Now I want to climb another 50 meters. I depress the collective brake (animated collective brake is depressed).

6. Increase the collective while still holding the brake depressed.

7. Autopilot is fighting me and is decreasing rotor blade pitch (it can be seen on the indicator that the rotor pitch at first increases a bit and then returns to previous level).

8. Shark does not climb unless I pull the collective lever beyond 20% authority of the alt AP channel (still holding the collective brake).

 

What am I doing wrong? Or what can be wrong? As I understand, with collective brake depressed AP channel should be off and I should be able to change rotor blades pitch freely. Thanks to everyone for their answers and time.

I'd say, you were doing it correctly and the described behaviour of the helo is odd... *goes to try it himself*

 

But post a .TRK, though.

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I've read this several times and I am doing exactly what's written there.

 

I have a very similar ( but completely different :) ) problem, in that the collective brake in my KA-50 doesn't seem to do anything at all.

 

I am rapidly coming to the conclusion ( despite reading every guide and watching every tutorial on the net ) that the KA-50 autopilot and trim systems are possessed by evil spirits with a perverse sense of humour. Gremlins probably.

---------------------------------------------------------

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Modules owned:- Bachem Natter, Cessna 150, Project Pluto, Sopwith Snipe

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I know the Problem... ive read the mentioned Manual about a hundred times... i do exactly what is described... and exactly how dr arrow described it happens to me...

 

btw: switching off altitude channel doesnt make sense, because the only Job of the collective brake is to stop this channel from working til you let the handle go... so without the altitude channel the collective brake is useless... at least if you´re not keen on zeroing the measurement on the bottom right of the HUD

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The only function of the collective brake in-game is to set a new altitude for the autopilot to hold when the altitude channel is engaged. In real life, it also releases the force on the collective that holds it in place when you take your hand off of it.

 

The collective brake sets the new altitude to be held by the autopilot when the brake is released.

 

In-game, pressing the collective brake doesn't do anything, other than set you up for the subsequent releasing of the brake.

 

As noted in the manual on page 6-10:

 

 

 

That may be slightly confusing (maybe something lost in translation?) but the idea is this: With the altitude channel engaged, releasing the collective brake sets the new assigned altitude. Pressing the collective brake doesn't do anything in-game.

 

In order to avoid "fighting" the autopilot when changing altitudes, you'll need to disengage the altitude channel, change to the new desired altitude, and reengage the altitude channel of the autopilot. Or you can just work through it and when you get to your new altitude, release the collective brake (or press and release if you weren't already holding it), which will set the new altitude at time of release as your new assigned altitude which the autopilot will then hold.

This is all well known here in this thread, I think, but there is still something odd...

 

There is no "damping" in the altitude channel, only in the pitch, roll and yaw channels (actually I'm not sure about yaw, either).

... as this seems to be not the case. Try this: get into a hover with alt hold disabled. I could hover (20 deg. C, no wind, 2xVikhr, 2xB-8) with a blade pitch of about 11 degrees. If you move the collective (quickly) up to 13 deg or down to 9 deg., the blade pitch gauge shows this in a 1:1 fashion.

 

Now enable the altitude hold channel and do the same (with collective brake released - the whole time!). You will notice, that the blade pitch angle is somewhat dampened. You will not be able to move the collective spot on to, i.e. 13 deg. as the alt hold channel counters your input and with a tiny delay reduces the blade pitch back to almost your starting value of 11 deg.

 

edit:

Erm ... hrmph. Disregard all what I wrote. I think, I got it now ...

Pressing the collective brake doesn't do anything in-game.
This is the key point, right? Releasing the coll.brake - "pressing the coll.brake button" - is NOT working like "pressing the trimmer button". The ALT HOLD channel is ALWAYS active (when enabled) and always trying to maintain a blade pitch that keeps the helo at the last set altitude. That is what I interpreted as "dampening" earlier in this posting...

 

:doh::D


Edited by Flagrum
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To me, "damping" and "holding" are two very different things, but you got the right idea. With the altitude channel engaged, the autopilot will attempt to hold the assigned altitude. The assigned altitude is set when you engage the altitude channel or upon releasing the collective brake.

Oh well ... whenever I think I understood something ...

 

When I read and re-read what you wrote, I thought I finally understood it. But guess what ... see what I now found in the manual (p. 13-20):

Squeezing the handle of the collective (which serves as a collective brake and altitude trim button) will cancel the altitude position signal; releasing it after moving the collective to a new position and flying to a new altitude will set the new altitude into memory and the system will maintain the new altitude.

This is now again what I expected in the beginning of this thread. And it is contradicting what you said ...?

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When I read and re-read what you wrote, I thought I finally understood it. But guess what ... see what I now found in the manual (p. 13-20):

 

Well then we should go by that... I'm assuming that what the book says and what is currently happening are NOT the same? That is, the book (pg. 13-20) says that pressing the collective brake should, essentially, temporarily suspend altitude hold until released. That was my original understanding way back in the day, but I guess I've gotten used to how it is now. I'm really used to the Mi-8, where pressing the collective force trim release button simply disengages the altitude channel. I'm going to delete my posts since they are just going to cause confusion. When I get a spare minute, I'll verify the current behavior against what the book is saying, and submit a bug report if necessary (unless someone else beats me to it). Thanks for digging into the manual.

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Well then we should go by that... I'm assuming that what the book says and what is currently happening are NOT the same? That is, the book (pg. 13-20) says that pressing the collective brake should, essentially, temporarily suspend altitude hold until released.

Correct - that is how I understand that passage, but ...

 

When I get a spare minute, I'll verify the current behavior against what the book is saying, and submit a bug report if necessary (unless someone else beats me to it). Thanks for digging into the manual.

 

... this is what the helo does (copy&pasted from my earlier posting, the greyed text):

Try this: get into a hover with
alt hold disabled
. I could hover (20 deg. C, no wind, 2xVikhr, 2xB-
cool.gif
with a blade pitch of about 11 degrees. If you move the collective (quickly) up to 13 deg or down to 9 deg., the blade pitch gauge shows this in a 1:1 fashion.

 

Now
enable the altitude hold
channel and do the same (with collective brake released/squeezed - the whole time!). You will notice, that the blade pitch angle is somewhat dampened. You will not be able to move the collective spot on to, i.e. 13 deg. as the alt hold channel counters your input and with a tiny delay reduces the blade pitch back to almost your starting value of 11 deg.

My conclusion: releasing the collective brake does not disengage the alt hold channel temporarily - similar to the way the other AP channels function - but instead the helo tries to maintain the former blade pitch angle.


Edited by Flagrum
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Correct - that is how I understand that passage, but ...

 

 

 

My conclusion: releasing the collective brake does not disengage the alt hold channel temporarily - similar to the way the other AP channels function - but instead the helo tries to maintain the former blade pitch angle.

 

You probably meant that pressing the collective brake does not disengage the alt hold channel as it should. Now it seems that pressing the collective brake has no effect on the ALT hold channel, collective brake release however assigns new altitude.

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You probably meant that pressing the collective brake does not disengage the alt hold channel as it should. Now it seems that pressing the collective brake has no effect on the ALT hold channel, collective brake release however assigns new altitude.

Exactly. :o)

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because the only Job of the collective brake is to stop this channel from working til you let the handle go... so without the altitude channel the collective brake is useless...

 

Not entirely sure about that, its first job is to keep collective stick stabilized when pilot is not handling it directly. Without a brake, the helicopter's vibrations may produce random movements on it.


Edited by sigzegv
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