Collective Brake - aka Collective Trim ... and why you should use it.

I read very often posts where people say ( after the usual troubleshooting like "have you controller-conflicts?"/"Do you know how to trim with your stick ?" /ect...) that they are confident how they should use the Trim ( Non FFB stick users ) but they often have still a annoying Bump in their Flightpath and they swear that they use the AutoPilotChannels in the the right way, but they are not able to nail it down what is wrong and they think it's a bug.

If you are one of these pilots , please read on and spread the word:

One major factor in the KA-50 for a stable flight path ,after the cyclic-trim and correct use of the AP-Channels , so you are able to fly almost 'hands-free' and allows you to put all left concentration in managing your weapon and sub-systems is the Collective Brake.

The Collective brake is not only a cosmetic gimmick in the cockpit - it has to be used nearly as often as the cyclic trim after you made adjustments to your rotor-pitch. -when you use the AP-Channels correctly.

The Collective Brake is normally the second most used item after the cyclic trim!

You have to use the Collective brake and the Altitude Hold in the right way,

together with the Cyclic Trim - and you will see that it will be very easy to hold a wished speed while holding a set alt.

Many people that fly the Ka-50 are so focused on the Cyclic trim that they forgot about the Pitch trim or they just simply don't know about it.

Using the Pitch Trim aka Collective brake will allow you to set speed and alt.

When you change anything in your collective position/rotor-pitch you have to tell your Altitude hold channel about it - and you do it with the collective brake.

That is something that just happens automatically in the real thing , as you have to press the collective brake to be able to move the collective... - so it is a no-brainier.

I have to admit that it needs a lot discipline to do it properly on a pitch-controller that is freely moving and has no physical brake on it that forces you to press it when moving (like the X-52 Throttle).

Having the collective brake pressed =

constant signal of the Collective-brake button through DCS.

and

also disabling the brake that holds the lever in place, so it becomes free moving and has no great friction , so you can make fine adjustments to your rotor pitch as needed.

If you don't - you will always have a very annoying Bump that let you swing like a sack when reaching the limits of the Alt Hold channel.

Further : And this can than be the key factor why you are not able to bring down your un-guided rockets/bombs precisely.

I made myself a collective that has this Brake functional so I'm forced to use it in a proper way without thinking about it at all:

>>> http://forums.eagle.ru/showthread.php?t=86015

, so I have to engage the collective brake to move the collective.

- and I have to say using it every time I change may rotor pitch that it stabilises my flight very much and I'm able to hold desired Alt while changing my speed without problems when the Alt-Hold AP-Channel is engaged.

Please read here to get the full info:

Ka-50 Flight Manual Page 84:

9. Collective brake - Assign altitude lever [F]. This lever serves two functions:

o Press this lever to disengage the collective stick brake before moving the stick. The brake is needed to prevent the stick from moving due to vibration or casual touch. (Not simulated - as this can only be made via a hardware-mod)

o Once the brake has been released and a signal is sent to the navigation system, the lever can be used to assign a new altitude when using the altitude hold flight mode.

23. Scale of Deviation from Assigned Radar Altitude. This index and scale appear when route mode is engaged with altitude hold. An assigned altitude is set each time you release the collective brake (see Collective stick description). After you reach the desired altitude you release the brake on the collective and the current altitude will be set as the Assigned Altitude. After that, the deviation index indicates deviation from Assigned Altitude in meters.

Transitional Flight Regimes

The barometric altitude hold mode can be engaged when radar altitude is above 50 m. To change your altitude when in altitude hold mode, press the collective brake lever; to retain it for the duration of the transition maneuver, release the brake lever. After this, a new altitude hold altitude will be set.

Attitude (angular) Stabilization Mode

Attitude, altitude, and airspeed stabilization modes are set by pressing the autopilot channel buttons (“K”, “T”, “H”, “B”) on the autopilot panel.

Pressing the “ТРИММЕР” (TRIM) button on the cyclic stick cancels the autopilot’s position signals for bank (K), pitch (T) and yaw (H) and releasing it places the angular position of the helicopter in 3D space in memory.

Pitch angle stabilization allows you to maintain airspeed corresponding to the given negative pitch angle.

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. Either the barometric or radar altitude is stabilized according to the selected position of the “БАР - РВ” (Baro – Radar altitude) switch on the autopilot panel. However, if the switch is set to the “РВ” position with channel “В” enabled and the true altitude is more than 300 m, the autopilot will stabilize to the barometric altitude automatically.

And here you will find another very useful "stable-flight-path-helper" that corrects a software-design failure as good as I'm able to :

How to unchain the rudder from trim - solution

And/Or just read my whole "Standard Ka-50 newbie reply" ;) :

http://forums.eagle.ru/showpost.php?p=1619851&postcount=14

Another good explanation:

 

http://simhq.com/forum/ubbthreads.php/topics/2628835/The_collective_brake_and_Altit.html

 

AlphaOneSix:

 

The collective brake works exactly like the trimmer on the cyclic, but where the trimmer on the cyclic is for the PITCH, ROLL, and HEADING channels of the autopilot, the collective brake is for the ALTITUDE channel. And just like the other channels, the autopilot only has 20% authority over the controls.

 

An example of using altitude hold in normal flight would go like this:

 

1. Flying along straight and level, you decide you want to change your altitude.

2. Press the collective brake button (F) and hold it.

3. Adjust your collective to begin a climb or a descent (still holding the collective brake button).

4. Arrive at your desired altitude and adjust the collective to halt your climb or descent (STILL holding that button!)

5. Let go of the button for the collective brake (after you've stabilized at the new desired altitude).

 

At this point, the altitude channel will do its best to keep you at that altitude (either barometric or radar altitude). Remember that your autopilot can only do so much (20%), so drastic changes in the cyclic (or drastic changes in altitude if using radar altitude hold) will cause the altitude hold channel to work improperly.

 

********************************************

 

Ok, I understand. But what happens if I don't press the F key, and just increase the collective and stabilize at a higher altitude? Will the autopilot descend back to the first altitude?

 

Or am I just "working harder against" the autopilot when NOT pressing F and increasing collective?

 

You are just working against the autopilot. I will explain:

 

You are zipping along at a nice stable airspeed and altitude, let's just say 200kph and 500 meters (no special meaning here, just some numbers). You have all autopilot channels on, including altitude. Suddenly, you decide that you are too hot, and your ventilator fan just isn't helping, so you think to yourself "Self, we must get up higher where it is nice and cool!" (I think your self has a great idea, by the way!). So you pull in some collective (let's say for argument's sake, you just pull in a teeny tiny bit of collective), and lo and behold, nothing happens! You VSI stays pegged at zero! So you pull in some more collective, still nothing...then a bit more...until FINALLY your VSI starts to move. "Great!" says self. So your climb is initiated and you have the rate of climb you want (never fast enough when you're sweating and you want some cool air, eh?). Eventually, you start feeling that nice cool air up at 2,000 meters flowing into the cockpit, and you decide that you're high enough, so you reduce the collective until your altitude stabilizes (VSI back at zero).

 

(but it never "quite" stabilizes...oh it gets close, but something seems amiss...but along you go, oblivious, etc.)

 

Hey! It's time to turn! (or slow down or speed up or whatever) So you start your bank (or whatever) and the aircraft starts to turn (or whatever)...but then starts to lose altitude (or even gain, depending on what the "whatever" is). "What?!?" says self, very upset that his altitude channel is not working.

 

Well, your altitude channel IS working. It is trying to hold you at 500 meters. Well, you're way up at 2,000 meters! What is going on?!

 

Remember back when you were at 500 meters, and you wanted to climb, so you pulled in some collective (a teeny tiny bit, if my memory is correct)? Well your collective input to the collective servo moved (oh yes indeed it did, since it is physically connected, it has no choice!) But your collective control rods are not the only thing that tell the collective servo what to do. The autopilot also has a say. And you autopilot says it wants to stay at 500 meters, so as you're adding collective, the autopilot is taking it right back out. Not out of your control input, but out of the servo. Eventually, your collective movement will exceed 20 percent of its travel. (Note: I have an X-52 throttle, it moved about 10-15%.) When your collective input exceeds 20% of its travel, the autopilot runs out of authority, and your input starts to work. So your started climbing...up and up...until you got to 2000 meters, then you lowered the collective to zero your VSI. The catch here is that your autopilot still wants to lower the collective, but it can't, as it's already "lowering" it by 20% (which you have happily overriden by moving the collective more and more).

 

Now if you do any maneuver that would cause a change in altitude (just about anything in a helicopter will do that, they sure are touchy), then your altitude would start changing, because your autopilot has done all that it can do.

 

About this time, you realize the error of your ways, and you hit your collective brake button (just a tap here will do). You have just told your autopilot that you want to hold THIS altitude (2,000 meters). Here it helps to know that your autopilot's input to the servo is not really a direct mechanical linkage like your collective is (it's all computery, using little things called feedback sensors that tell the autopilot exactly where your collective is set and how much pitch is in the blades, etc....very complicated and all that). So when you hit that button, not only does it tell your autopilot to hold this new altitude, it ALSO zeroes your autopilots collective input! Now your autopilot once again has the authority to make minor changes to the collective servo to hold your altitude, and you're back to making turns, etc, without losing or gaining any altitude!

 

Yay! Everyone wins!

...and a MadDog-IC

shows you how to program a script that automatically press the collective-brake for you whenever you move the collective.

Start reading here:

>>> http://forums.eagle.ru/showthread.php?p=1800980#post1800980

Great post am already writing down this information in my flight notebook, Learned two more things today that will help me master the KA-50 even more.

Thank you! rep coming

Can you explain how the alt hold channel might not cope when increasing collective against it or just other ways this bump happens just trying to get the fine points written down.

Good post, I started using it more often recently since I mapped the collective break to an easy to click button on the joystick. Works as advertised :)

Fantastic post Thankyou PeterP, I will admit in all my years flying blackshark, I have never used the Collective Brake, thinking it was cosmetic, and always struggled with keeping a constant altitude.

Now with this new knowledge I just may be able to do that. Thanks again.

Cowboy10uk

Really thanks Peter.

I use collective brake. But I see now that I wasn't using it really properly.

Thanks again.

Thanks Peter I think I have one more slider not used on my X52. So I'm releasing the brake when I change rotor pitch then gradually re-apply the brake to settle the Alt hold AP channel to the new altitude ?

made my birthday!

 

Can you explain how the alt hold channel might not cope when increasing collective against it or just other ways this bump happens just trying to get the fine points written down.

Please make your own tests with the collective-brake and the ALt-Hold channel engaged as explained in the flight-manual.

Explaining it again in my own words will be just a repeating what I have posted before and comes close to explain colours to a blind person.

... you have to 'see' it with your own eyes to believe it . ;)

Thanks Peter I think I have one more slider not used on my X52. So I'm releasing the brake when I change rotor pitch then gradually re-apply the brake to settle the Alt hold AP channel to the new altitude ?

Yes. - But you don't gradually re-apply it . You just press it down every time you change your rotor-pitch via the collective and you use it also just without changing the pitch to set a new target-alt.

See these Quotes from Post #1 for clarification and also re-visit the manual entries - and as always - make your own tests in the sim to get used to it (you will be amazed how stable you can hold your alt while in Hover-Hold mode "hands free" in the cockpit...) :

When you change anything in your collective position/rotor-pitch you have to tell your Altitude hold channel about it - and you do it with the collective brake.

That is something that just happens automatically in the real thing , as you have to press the collective brake to be able to move the collective... - so it is a no-brainier.

 

[...]

 

Having the collective brake pressed =

constant signal of the Collective-brake button through DCS.

and

also disabling the brake that holds the lever in place, so it becomes free moving and has no great friction , so you can make fine adjustments to your rotor pitch as needed.

Fantastic post Thankyou PeterP, I will admit in all my years flying blackshark, I have never used the rotor break, thinking it was cosmetic, and always struggled with keeping a constant altitude.

 

Now with this new knowledge I just may be able to do that. Thanks again.

 

Cowboy10uk

I'm fairly confident that it's a typo and you don't mean the rotor-brake.

As you only want to engage it when you have shut down the engines and you park - so your blades don't start spinning by the slightest wind.

...So for clarity sake :

We are talking about the Collective Brake in this Thread (not the Rotor Brake).

Please make your own tests with the collective-brake and the ALt-Hold channel engaged as explained in the flight-manual.

Explaining it again in my own words will be just a repeating what I have posted before and comes close to explain colours to a blind person.

... you have to 'see' it with your own eyes to believe it . ;)

 

 

 

Yes. - But you don't gradually re-apply it . You just press it down every time you change your rotor-pitch via the collective and you use it also just without changing the pitch to set a new target-alt.

 

See these Quotes from Post #1 for clarification and also re-visit the manual entries - and as always - make your own tests in the sim to get used to it (you will be amazed how stable you can hold your alt while in Hover-Hold mode "hands free" in the cockpit...) :

 

 

I'm fairly confident that it's a typo and you don't mean the rotor-brake.

As you only want to engage it when you have shut down the engines and you park - so your blades don't start spinning by the slightest wind.

 

...So for clarity sake :

We are talking about the Collective Brake in this Thread (not the Rotor Brake).

:doh: yep ok, good catch, but you know what I meant. Really shouldn't type after a few beers.:megalol:

Post one edited.

Cowboy10uk

Very useful post, as always. Thank you very much.

"Sticky" proposed

Very useful info. Thanks.

At last! I can fly that thing smoothly! Tx for the post! I purchased the Shark from the get go and I was forever struggling with it. After reading this post last night, I decided to really put efforts into settings my G940 properly (and assigning the collective brake to my throttle) and use the autopilot channels and the flight director, route following etc the way they were intended to be used. Now I can fly around, follow a route, attack a target, whatever! I can't believe how screwed up my understanding of this bird was. And to say i'm a real life pilot! (fix wing). Dude, you made my day! Thanks again!

Thank you !- very happy to read your words - and that a twisted mind , like I am, is able to teach a RL Pilot something new :)

ty for the info Peter !:)

Good stuff. Forever relevant, so bump.

can someone suggest a good button to map this to on the X52 or X52 pro? (and don't say the pinky button, cuz that's a modifer for me that I can't live without) :-)

can someone suggest a good button to map this to on the X52 or X52 pro? (and don't say the pinky button, cuz that's a modifer for me that I can't live without) :-)

i made an F key macro and made it to work on the slider on the HOTAS all the way down is off all the way up its on, works rather nicely.

i use the pinky for heading AP on/off so its no go for me too.

Same; I use slider on throttle for Collective Brake.

can someone suggest a good button to map this to on the X52 or X52 pro? (and don't say the pinky button, cuz that's a modifer for me that I can't live without) :-)

This works quite well for me on the x52 pro, I think it works just like the real thing and I don't have to think about it, it is automatic, move the collective stick and the collective brake is held in, stop moving the collective and gives you 3 seconds to stabilise to new altititude then the collective brake is automatically released.

If 3 seconds is too long for you, just modify the macro time to what you would prefer.

I read very often posts where people say ( after the usual troubleshooting like "have you controller-conflicts?"/

"Do you know how to trim with your stick ?" /ect...) that they are confident how they should use the Trim ( Non FFB stick users ) but they often have still a annoying Bump in their Flightpath and they swear that they use the AutoPilotChannels in the the right way, but they are not able to nail it down what is wrong and they think it's a bug.

 

 

If you are one of these pilots , please read on and spread the word:

Thanks for the post, I had never used the collective brake in the past, as I couldn't spare another of the HOTAS buttons and it didn't really seem to interfere with my flying style, but your post did get me to thinking and have now put it to use.

Programmed saitek x52pr SST to hold the collective brake in when ever the collective is moved, and release it 3 seconds after you stop adjusting the collective, so as far as I can tell it acts pretty much as the real thing.

Have posted in another reply, how it's done.

Cheers

 

Programmed saitek x52pr SST to hold the collective brake in when ever the collective is moved, and release it 3 seconds after you stop adjusting the collective, so as far as I can tell it acts pretty much as the real thing.

 

 

Cheers

Genius! Very nice trick! Thanks a lot, sir!

This was helpful to me:

http://simhq.com/forum/ubbthreads.php/topics/2628835/The_collective_brake_and_Altit.html

The example given in the above link seemed to do a better job of explaining what the whole COLLECTIVE BRAKE actually does.

That AlphaOneSix dude doesn't know what he's talking about....

Which reminds me, Mi-8MTV-2 has a collective brake...sort of. But when you press it, it kicks off your altitude channel!

..yes, he knows some things and what he is talking.

;)

edited post one - added direct link to alphas explanation and also to MadDogs input script.

That AlphaOneSix dude doesn't know what he's talking about....

 

Which reminds me, Mi-8MTV-2 has a collective brake...sort of. But when you press it, it kicks off your altitude channel!

well he explained better than anyone else on this here 'net. :smilewink: