correct as-is Helicopter control problem

[W_Prytz]

Hello, first of I just want to say that this problem is happening in all Helicopters I've used, not only the Apache but since I couldnt place it in a general helicopter forum, I've placed it here. The problem is that as soon as I raise the collective, the helicopter starts turning aggresivly to the right. I've checked and I can't find any double bindings. When I raise the collective furhter, the turn to the right becomes more aggresive. The movement to the right is identical to which if I would have applied rudder force. But the rudder pedals do not move when I raise the collective, so I suspect it may be something else than a doubel-binding. 

Has anyone experienced this before?

Any ideas?

Thankful for any answers

[edmuss]

That's normal operation for a conventional helicopter*. The main rotor imparts torque on the airframe, more collective = more torque which needs to be compensated for by putting in rudder pedal input which increases pitch on the tail rotor to keep it all straight.

As I understand it, helicopter rudders pedals are actually anti-torque pedals and aren't sprung to centre, they stay where you leave them; most decent sim rudder pedal setups can have the spring disconnected to simulate this.

*Coaxial counter-rotating rotor blade helicopters like the KA50 don't suffer from this issue when applying more collective as the blades torque cancels each other out.

edit: to the best of my knowledge, american helicopters rotate clockwise and need left pedal input to keep them straight, soviet helicopters are opposite and require right pedal input.

Edited December 23, 2022 by edmuss

[W_Prytz]

While waht you said might be true, I still think there is a problem. If I go full rudder to compensate, it still turns to the right. 

So if its only due to the natural rotation you mentioned, can I reduce it somehow? Because it's greatly over exaggerated. The heli is out of control.

[admiki]

OK, so you say you have checked bindings for any double inputs. We'll presume it's clear.

As edmuss said, pedals don't work in the same sense as in an airplane, aka, just because pedals are centered doesn't mean there wont be any yaw. You said it happens in all helicopters? 

Which ones have you used so far? Only US or also Russian birds?

Also, depending on your weight and conditions in which you fly, full left pedal might not be enough to compensate for the torque (also happens in real life)

Best way for us to help you is if you post a short track here or post a video of the issues (in that case, make sure you have controls indicator on so we can see what your controls are doing)

[W_Prytz]

I've so far used the KA50, the Gazelle, and the apache. The problem is just the same with the others. Maybe Im just new to DCS heli dynamics, in that case sorry for creating an unesccecary topic. https://drive.google.com/file/d/18-rR5N5oiy4-gCH-9FUZG1r0SPt4Wp26/view?usp=share_link

Here is a link to video, please let me know if it doesnt work!

 

[admiki]

1 hour ago, W_Prytz said:

I've so far used the KA50, the Gazelle, and the apache. The problem is just the same with the others. Maybe Im just new to DCS heli dynamics, in that case sorry for creating an unesccecary topic. https://drive.google.com/file/d/18-rR5N5oiy4-gCH-9FUZG1r0SPt4Wp26/view?usp=share_link

Here is a link to video, please let me know if it doesnt work!

 

You can't pull FULL collective and expect pedals  to counter that (and by full I don't mean 100% engine power, but physical range)

And you need to apply some left pedal before you even leave the ground.

Ka-50 doesn't need pedal due to coaxial rotors, Gazelle is not a book example of good helicopter flight model.

I don't want to be rude, but maybe you should watch a few videos on helicopter flight and controls.

After that try to pull just enough collective to get off the ground (around 90-98% engine power)

[sirrah]

1 hour ago, W_Prytz said:

I've so far used the KA50, the Gazelle, and the apache. The problem is just the same with the others. Maybe Im just new to DCS heli dynamics, in that case sorry for creating an unesccecary topic. https://drive.google.com/file/d/18-rR5N5oiy4-gCH-9FUZG1r0SPt4Wp26/view?usp=share_link

Here is a link to video, please let me know if it doesnt work!

 

Did you read @admiki's advise (3 posts up) to check your controls setup?

 

Looking at the violent right turn in your video, there seems to be more going on than just lack of sufficient left rudder input. I suspect you accidentally have one of your controller axis bound to the rudder (and have that axis set to full right input).

You can also easily check this by enabling the control input overlay in DCS settings.

 

If the above is not the case, I suggest you to post a short track file here. There's very little to go by, with just a video. A track file (if not broken ) provides a lot more info.

Edited December 23, 2022 by sirrah

[Yurgon]

2 hours ago, W_Prytz said:

Here is a link to video, please let me know if it doesnt work!

Thanks for the video.

Like Admiki said, be very gentle with all your inputs!

Pulling full collective is almost guaranteed to cause problems in just about any helicopter (rotor RPM droop, over-torque, exceeding engine and exhaust temperatures, and probably a bunch of other things that will all try to kill you).

Gently and slowly raise the collective until the chopper just barely goes airborne. Counter the helicopter's yaw with the correct pedal; in case of the Apache and the Huey that's the left pedal, in case of Hind, Hip and Gazelle it's the right pedal, and in case of the KA-50 there should be very little yaw to counter on a standard takeoff because, like the others already said, the counter-rotating rotors cancel out each other's torque.

With a bit of experience, you'll be able to apply just the right amount of pedal before you see the nose yaw. But for starters, observe the yaw and then counter it.

In the meantime, the tail rotor is going to push the helicopter sideways, so use the cyclic to counter that motion (a tiny bit of left cyclic in Apache and Huey).

Finally, most helicopters have a tendency to go forward with the cyclic perfectly centered, so you may have to apply a bit of aft cyclic to get the helicopter into a low hover and remain stationary.

But, all that said, whatever you do with your controls, do it slowly and gently. The way you slammed the cyclic up in the video is way, way, way too fast and aggressive and will destroy just about any chopper, either because of thermal and/or mechanical failure, or by going immediately out of control. You never, ever want to hear Bitching Betty call out "Rotor RPM Low". When you hear that, you've already done something terribly wrong!

57 minutes ago, sirrah said:

You can also easily check this by enabling the control input overlay in DCS settings.

In the video that W_Prytz posted, the controls indicator is visible and there is no right rudder input at all. After spinning the helicopter totally out of control, full left pedal is applied, but at that stage the tail rotor simply can't stop the immense yaw.

Edited December 23, 2022 by Yurgon

[Yurgon]

On 12/23/2022 at 12:12 PM, W_Prytz said:

The problem is that as soon as I raise the collective, the helicopter starts turning aggresivly to the right.

I just recorded a small track from the Runway Start Instant Action mission. This is from the Open Beta 2.8.1.34667; if you're still on 2.7 Stable let me know and I'll re-record the track because the flight model changed between versions and the replay won't work there.

Can you run the track in your DCS and let us know how it plays? You should see the helicopter go into a stationary 5 foot hover (might have been 6 foot, and not that stationary, but hey, it's just for demo purposes) and then come back down to a landing with a little bit of right drift that I failed to properly counter.

If that's how it plays for you, watch the controls indicator for the types of input I'm giving - and then try it yourself.

 

Edited March 27 by Yurgon
Attachments removed

[sirrah]

1 hour ago, Yurgon said:

 

In the video that W_Prytz posted, the controls indicator is visible and there is no right rudder input at all. After spinning the helicopter totally out of control, full left pedal is applied, but at that stage the tail rotor simply can't stop the immense yaw.

 

Ah yes, I see now

[admiki]

8 hours ago, W_Prytz said:

I've so far used the KA50, the Gazelle, and the apache. The problem is just the same with the others. Maybe Im just new to DCS heli dynamics, in that case sorry for creating an unesccecary topic. https://drive.google.com/file/d/18-rR5N5oiy4-gCH-9FUZG1r0SPt4Wp26/view?usp=share_link

Here is a link to video, please let me know if it doesnt work!

 

I was tight on time today, so had to make it short and dirty, sorry if I came out rude, that wasn't my intention.

As already said, you need some pedal even before you leave ground, which one depends on the way your rotor turns (for US helicopters use left pedal).

So, you had two causes for your problem in that video. They are both caused by your collective control.

First one is huge amount of torque you demanded from your helicopter, caused by huge drag produced by your main rotor blades as you pulled full pitch on them. Imagine puting your palm out through your car window at high speed and turning it perpendicular to airflow. Now multiply that force by few thousand times.

Second one is losing rotor RPM by demanding a lot of torque which engines can't produce. It is important due to gearing ratio for tailrotor. Tailrotor spins a lot faster than main rotor. Depending on design, that ratio can be up to 1:8 for conventional tailrotor, to 1:15-20 for fenestron type. It is always more efficient to move a lot of air mass at slow speed (main rotor disc area) than to move small air mass at high speed (which is exactly what a tailrotor is doing). Tailrotor is already at disadvantage in trying to compensate for mainrotor torque. Now imagine what happens to that tailrotor if you lose 50 RPM on main rotor?

So, what can you do to try to succeed? First of all, lift your collective slowly. At some point helicopter will start to move as it gets light on its landing gear. At that point move your cyclic and pedals to stop that movement and then continue to slowly pull collective. Before you know it you will be flying. 

One more thing you can do while learning this is to create your own mission and make helicopter light. Drop all weapons, drop half the fuel. Lighter you are, less power you will need to get in the air and you will have less inertia to fight against.