The Trim System and Flying Tips

[Oubaas]

I think that there is a tendency among helicopter pilots, real or virtual, to expect all rotary-wing aircraft to behave like some variation of a Bell product. But the Gazelle is a completely different platform.

 

If there was such a thing as a fighter helicopter, this might be one. It's agile and powerful.

 

The trim system is unlike the Huey, the Mi-8, or the KA-50. But once you make the right control assignments and learn to use it, it is nothing short of brilliant.

 

You need to assign a button for "trimmer". This seems to engage or disengage the trim system and nothing more. You don't hold it and adjust the flight controls. It's either on or off and you just need to hit the button and release to set it or turn it off.

 

Once you have hit the "trimmer" button, you can then use the buttons that you have assigned to trim nose up or down and to trim left or right wing down. These buttons adjust trim in their axes in small increments. Once trimmed out correctly, the Gazelle is so stable that you can fly hands off. And take note: YOU DON'T need to center the stick when you adjust trim as in the other helicopters and you DON'T need to press and hold any of the buttons. Just keep flying and tap the trim buttons until you're oriented the way you want it. This trim system does not work like the other choppers.

 

The aircraft is in fact SO stable when trimmed that I sometimes hit the "trimmer" button and turn it off so that I can fly manually. The aircraft is considerably more "lively" without the trim system on.

 

Taking off, do not yank up on the collective. Bad things will happen. Smoothly and gradually pull up on the collective and be prepared to give it some right pedal as you lift off and to adjust bank. Ascend at a conservative rate and when you've gained enough altitude to avoid impacting the ground, you can then transition and get things going. And remember, the anti-torque pedals are quite sensitive and you'll mostly need to give it right pedal.

 

You should consider setting some deadzones and axis curves for the controls until you're used to the aircraft. You can always undo them later. I don't like using curves, but I used some mild curve on the axes until I got the hang of the Gazelle.

 

Landing is easy in the Gazelle if you do it right. Watch the VSI and trim to a reasonable rate of descent. Gently reduce collective to lower your forward speed as you descend and just before touchdown give it some flare. You should alight like a feather if you take your time and monitor things.

 

Once you've mastered the unique trim system, turn off trim and get used to flying the aircraft manually. It's not hard and by now you should have the feel for the aircraft.

 

My own opinion, after flying the Gazelle for a day, is that Polychop has presented us with a masterpiece. If this is what I can expect from them, I'll be buying everything they offer. I wouldn't change a thing about the Gazelle, especially the trim system. Once you learn to use it, it is a superior system to the center trimmer on the other helicopters. You just have to understand how it works and learn to use it correctly.

 

But you can't expect it to be the same as other helicopters. It's a unique machine and very rewarding if you come to grips with the differences.

 

Oubaas :thumbup:

Edited April 30, 2016 by Oubaas
Added information.

[TomCatMucDe]

By "trimmer" do you mean magnetic brake button on the stick or trimmer switch on the main panel?

[nomdeplume]

Yes, I think the other thread describes it better. The dual-trim systems is pretty cool.

[Oubaas]

I'm not sure where the switch animations occur, I haven't learned the panel well enough yet. But the key to proper use of the trim system is set up in the control options as follows.

 

Adjust roll left Trim: Left Wing Down CTRL + ,

Adjust nose down: Trim: Nose Down CTRL + ;

Adjust nose up: Trim: Nose Up CTRL + .

Adjust roll right: Trim: Right Wing Down CTRL + /

Turn trim system on and off: Trimmer T

 

I have assigned the flipper buttons on my CH Throttle Quadrant to these functions in lieu of the default keyboard shortcuts listed above. Simply press and release the "Trimmer" button. Then adjust the aircraft attitude by pressing and releasing the desired "Trim" button.

 

There is no need to press and hold any buttons. Just press them once and release. There is also no need to center your stick, just trim on the fly.

 

 

 

[dotChuckles]

This advice is only relevant if you have a ffb stick (which isn't implemented yet), or a stick with no centering spring. Also I suggest you re-read the manual as your understanding of how the magnetic hold system works is not quite right.

[Oubaas]

This advice is only relevant if you have a ffb stick (which isn't implemented yet), or a stick with no centering spring. Also I suggest you re-read the manual as your understanding of how the magnetic hold system works is not quite right.

 

I have a non-FFB stick with a centering spring. I just took off from Creech a few minutes ago, ascended to cruising altitude, trimmed the aircraft for level flight and flew all the way to Nellis with no hands on the controls or feet on the pedals.

 

I don't think I'm the one having problems with the trim system.

[Esac_mirmidon]

Magnetic Trim is de "European" word for the more common USA Force Trim denomination but both are the same trim concept with different names.

 

So dont get confused by "magnetic" words.

[dotChuckles]

I have a non-FFB stick with a centering spring. I just took off from Creech a few minutes ago, ascended to cruising altitude, trimmed the aircraft for level flight and flew all the way to Nellis with no hands on the controls or feet on the pedals.

 

I don't think I'm the one having problems with the trim system.

 

Ok, have a nice day. :music_whistling:

 

If you can't see the control spiking after you trim then I can't discuss this further. Also, if you are flying hands off... then that means you have re-centered your stick, which is contrary to your own "advice"

 

And take note: YOU DON'T need to center the stick when you adjust trim

 

So yeah. Done here. I'm glad that is works for you. But don't presume my level of understanding.

[Oubaas]

Ok, have a nice day. :music_whistling:

 

If you can't see the control spiking after you trim then I can't discuss this further. Also, if you are flying hands off... then that means you have re-centered your stick, which is contrary to your own "advice"

 

 

 

So yeah. Done here. I'm glad that is works for you. But don't presume my level of understanding.

 

I don't get any control spiking. And I don't re-center the stick. I'm having no problems whatsoever with flying or trimming the Gazelle. None.

 

But don't take my advice. What could I possibly know? I'm just an old guy, retired from U. S. Naval Aviation. True, during my last flight physical the doctor barred me from rotary aviation due to a loss of depth perception, fixed wing only after that, but in retrospect, it was probably for the best, me being so ignorant and all.

 

Your impeccable understanding will take care of you. Keep reading that manual. Meanwhile, I'll go enjoy flying a great helicopter without having any problems whatsoever. After all, they say ignorance is bliss, and I'm happy as the proverbial clam.

 

:megalol:

[dotChuckles]

I'm sure all your time in the US navy gave you many hours in a Gazelle. I'm very jealous, I only ever got to fly in it left seat a couple of times.

 

If you don't see the spiking, then good for you. I will quite happily post a video demonstrating it.

 

Enjoy.

[HawkDCS]

Oubass do you seem to run out of trim? If I am at say 80%+ Power/Torque there doesn't seem to be enough trim nose down to stop the climb?

 

How are you getting the trimmer to work? I am holding stick where I get nose level then hit the trimmer when I release back to center the helicopter will porpoise and act like nothing was changed. Sometimes it will be even worse than before I hit the button.

 

I am using the button trimmer for large adjustments when I run out of fine trim to hold nose down.

 

I am having same trouble with it as Dot I am also a RL pilot but never flown anything but Bell 206.

 

I guess I will try to use it as an on off button for the trim system.

 

The manual does say that the Magnetic Brake Trimmer button should hold the stick in the position its in when button is pressed its in 2.5.1. So its not just an on off it would seem.

 

Thanks for any help.

Edited April 30, 2016 by HawkDCS

[AlphaOneSix]

There is definitely some odd information going on here.

 

Helicopters, especially modern ones with hydraulically-boosted flight controls (of which the Gazelle is but one example), have one or two "trim" systems. For lack of a better description, I like to call these two systems "force trim" and "beep trim".

 

So far in DCS, the helicopters have all only had "force trim".

 

As we already know, this system uses electromagnetic brakes built into the flight controls to create and maintain a "center" position for the flight controls. You can press the force trim release switch, and the electromagnetic brakes will allow the flight controls to be moved around with very little force, and no center. When you release the force trim switch, the electromagnetic brakes in the flight controls are engaged, and springs built into the electromagnetic brake assemblies hold the flight controls in place. This is often referred to as "artificial feel". You can still move the flight controls around, but in order to do so, you must overcome the "artificial feel" created by the springs in the electromagnetic brakes.

 

The system described above exists in just about every modern helicopter I can think of that has hydraulically-boosted flight controls. It exists on the three current DCS helicopters, and it exists on the Gazelle.

 

Next we have the "beep trim" system. A lot of Western helicopters(and even some Russian ones, depending on avionics (I'm looking at you, Mi-17KF)) have this system nowadays, especially those with advanced autopilot systems. What the beep trim does is use china hats that allow for "fine tuning" of the control position in the exact same way that fixed-wing aircraft adjust trim. There would be at least one, and sometimes two china hats used for this purpose. One will be the china hat on the cyclic, used for trimming pitch and roll. Some aircraft will have another china hat (or similar) on the collective that is used to trim altitude and heading. When you use the cyclic beep trim, it physically moves the cyclic in your hand. It is basically using an electric trim actuator to move the controls instead of your hand/arm. In most cases, the trim actuator and the electromagnetic brake are the same device. (I say "most cases" but in every helicopter I've worked on that has beep trim, the trim actuator and the electromagnetic brake are the same unit.)

 

You can use the beep trim (china hat) to do all the trimming, if you wanted to, but I've never seen it done this way. Instead, the force trim release is used for gross (as in large, not yucky) adjustments, while beep trim is used for fine adjustments.

 

For example, when picking up the helicopter to a hover, you would normally use the force trim release (maybe continually, maybe periodically) until you established a more or less stable hover...then you could use the beep trim to hold that hover (although in my experience, the force trim release is still used to maintain a hover). When you transition to forward flight, you would again use the force trim release to establish your cruising attitude. Once you got to your desired heading, airspeed, and altitude, you would generally stop using the force trim release to maintain that attitude, and instead use the beep trim to make fine adjustments to the aircraft's attitude.

[Oubaas]

Oubass do you seem to run out of trim? If I am at say 80%+ Power/Torque there doesn't seem to be enough trim nose down to stop the climb?

 

How are you getting the trimmer to work? I am holding stick where I get nose level then hit the trimmer when I release back to center the helicopter will porpoise and act like nothing was changed. Sometimes it will be even worse than before I hit the button.

 

I am using the button trimmer for large adjustments when I run out of fine trim to hold nose down.

 

I am having same trouble with it as Dot I am also a RL pilot but never flown anything but Bell 206.

 

I guess I will try to use it as an on off button for the trim system.

 

The manual does say that the Magnetic Brake Trimmer button should hold the stick in the position its in when button is pressed its in 2.5.1. So its not just an on off it would seem.

 

Thanks for any help.

 

I haven't noticed a problem, Hawk, I even use the trim to set up my glide slope on approach while I reduce collective far below 80. But I'll go fly it around and see if I can duplicate what you're describing.

 

I think AlphaOneSix has given us the best description yet of what's going on with the trim in this aircraft. I've been using the beep trim after manually flying the aircraft into transition and then establishing my desired altitude and attitude. I'll have to play with the force trim and try a few gross adjustments, but the way I fly, the beep trim suffices for pretty much all of my trim needs.

 

:thumbup:

[wolle]

As Alpha Six said, we should have both trim modes available to us. But as far as I can tell, 99% of us (non-FFB users) now have only the trim hat method available, force trim doesn't work for us. Therefore we need force-trim simulated for non-FFB users in the same way as it is now in the other choppers. Or am I missing something?

[dotChuckles]

As Alpha Six said, we should have both trim modes available to us. But as far as I can tell, 99% of us (non-FFB users) now have only the trim hat method available, force trim doesn't work for us. Therefore we need force-trim simulated for non-FFB users in the same way as it is now in the other choppers. Or am I missing something?

 

Nope, exactly. Currently when you force trim the controls spike and you have a momentary small bump or porpoise, which is not correct, or how the real aircraft behaves. It will then settle into trimmed flight, the desired result. The solution is a central position mode.

 

You, have understood it fully.

[HawkDCS]

So after it does it porpoise it will settle to where you force trimmed it?

 

I will try that again then. I seem to fly it through the bump then re force trim then give up haha.

[dotChuckles]

So after it does it porpoise it will settle to where you force trimmed it?

 

I will try that again then. I seem to fly it through the bump then re force trim then give up haha.

 

Yes, it will settle out to where you trimmed it, curves and saturation effect the severity of the spike as it appears to be a proportion of stick deflection so experiment, and you can tune it out to a degree. Also smooth hands will prevent the spike causing a PIO.

 

Still not right though, or how the system works, but I'm sure they will get to fixing it as everything else in this module is so damn good.

[Oubaas]

HawkDCS is definitely onto something about running out of trim. I was all set to A799 this gripe until I flew the helicopter and tried it.

 

If you transition and trim level with the collective above 80% using the "beep" trim method, you will have no problems.

 

But if you transition and trim level at 80% collective or below, you'll soon find that you can't trim the nose down with the beep trimmer.

 

As for force trim, I can't find any evidence that it does anything. All my trimmer button seems to do is engage or disengage the beep trim. I tried gross trim adjustments with the trimmer button all sorts of different ways, tapping it, holding it, etcetera, no joy.

 

If this aircraft is supposed to have both a force trim system and a beep trim system, only the beep trim is working. It seems to be entirely adequate if you use it to augment your manual flying. But if the real aircraft has both systems, then I'd like for them both to work.

 

In the meantime, the beep trim system can very easily be used to trim to hands off flying. As far as the beep system goes, I really like it.

[dotChuckles]

So are we ready to agree then that the trim system is not behaving as designed on the real aircraft? As your experience is totally contrary as to how the real aircraft works.

[HawkDCS]

Thanks Oubaas. Glad its not just me!

 

Yes it is supposed to have both systems according to manual. I figure in the real AC you would probable force trim to get close then beep trim for cruise. The force trim seems to be screwed up.

[sabreman]

This is how the trim system works:

 

[ame]

[/ame]

 

It's really straight forward guys.

[Esac_mirmidon]

Thanks for the video.

 

End of the discussion....... XDDDDD

[Flagrum]

This is how the trim system works:

 

 

It's really straight forward guys.

Straight forward like that wobble that can be seen in the controls indicator? That is, afaik, the only thing that (non-ffb) people bothers. That is not present in other helos. Either it is smoothed out, or the aircraft only accepts inputs from the stick again after(!) it was centered (depending on the Options->Misc settings).

 

Such a bump in the cyclic ... kills you in a Gazelle where all inputs are usually made within millimeters. :o)

[RazorbackNL]

How would a non-FFB joystick with no centering springs benefit from the magnetic trim? I have the option FFB checked and a G27 wheel is hooked up, making DCS think my joystick is ffb. In all the other helicopters I do not have the virtual cyclic spike anymore because of this setup. Would the Gazelle make good use of this also?

[dotChuckles]

Thank you. Sabreman. This is exactly what was needed. This is what the OP wasn't understanding.

 

However when I press the force trim button, and others are experiencing a control spike immediately after release, upon moving the stick back to center. It's like there isn't a "wait until centered" clause or a timeout to let you smoothly center the stick.