X-Plane 12: And Now for Something Completely Different ...

[Soul Rebel 39]

1 hour ago, flying_carpet said:

Do you think it isn't?

That's anything but realistic.

[flying_carpet 657]

18 hours ago, Soul Rebel said:

That's anything but realistic.

Proof? Can you elaborate it? Have you flown or operated this specific helo IRL? How much more realistic is this depicted in your sim of choice?

[flying_carpet 657]

Yet another incident ...

... yaw (rudder) left control hard left (like these)

 

[UrgentSiesta 942]

5 hours ago, flying_carpet said:

Proof? Can you elaborate it? Have you flown or operated this specific helo IRL? How much more realistic is this depicted in your sim of choice?

While I like the fact that a (really old) default addon has failures of any sort, it is indeed an inaccurate depiction of that class of failure.

If the collective were yanked hard enough to whack the torque up like that, we'd actually see rotor rpm drop significantly, instead of the apparent rotor over-speed. And that sudden of a torque increase might even be enough to hop the helo completely up off the ground, too.

Fuel flow shouldn't be wildly affected because helos don't really fly with engine "thrust" changes - the turbines are just there to keep the rotors spinning within a fairly narrow rpm range. I.e., the rotor blades generate movement, not the turbines.

Overall, I'd be less surprised to see this result from some catastrophic hydraulic or perhaps physical linkage failure than turbine overspeed, etc., but it doesn't appear the hydraulic gauges reflect anything like that, etc.

Again, that there are failures at all in this very old addon is impressive. This particular failure? Meh - understandable. But if I saw this manifestation in one of X-Trident's or other quality 3PD's helos, I'd be genuinely bothered.

[Murmur 3,944]

3 hours ago, UrgentSiesta said:

If the collective were yanked hard enough to whack the torque up like that, we'd actually see rotor rpm drop significantly, instead of the apparent rotor over-speed. And that sudden of a torque increase might even be enough to hop the helo completely up off the ground, too.

Fuel flow shouldn't be wildly affected because helos don't really fly with engine "thrust" changes - the turbines are just there to keep the rotors spinning within a fairly narrow rpm range. I.e., the rotor blades generate movement, not the turbines.

I've done a test myself, and the actual failure simulated in this case is, as we could call it, a "throttle runaway" (it is listed as "rotor controller failure" in the failures screen, indeed poor wording).

In other words, it simulates a failure of the engine governor that causes engine throttle to runaway at max. So, the effect per se seems to be implemented realistically: both fuel flow and rotor RPM go to max, since blade pitch / collective are not affected.

Now that being said, I don't know if the real S76 engine governor has this as one of its possible failure modes or not.

EDIT: Looks like X-Plane is correctly modeling a so called "High Side Governor Failure":

Quote

HIGH SIDE GOVERNOR FAILURE

During a high side governor failure, the fuel control unit supplies the engine with an excessive amount of fuel. In a single engine helicopter, a high side governor failure would result in an increase in rotor rpm. Because the engine parameter gauges would show a high value, the natural reaction would be to lower the collective. If the collective is lowered during a high side governor failure, a catastrophic speed increase in the rotor rpm can occur. Therefore, the majority of rotorcraft flight manuals recommend not lowering the collective initially if a high side governor failure occurs.

https://it.scribd.com/document/128438237/Governor-Failures#

Well done, X-Plane!

Edited August 10, 2023 by Murmur

[Greazer 1,345]

15 hours ago, flying_carpet said:

Yet another incident ...

... yaw (rudder) left control hard left (like these)

 

Probably not an XP bug but a controller issue, such as noisy rudder axis or what not. Can not blame Devs for that 😁

[Soul Rebel 39]

21 hours ago, flying_carpet said:

Proof? 

You are the one uploading the video aiming that It's something realistic so you are the one that should give proof not the other way around.

 

21 hours ago, flying_carpet said:

Can you elaborate it?

You had and overspeed in not one but two turbines at the same time, something almost impossible in real life.

You had a dual DECU (Digital Engine Control Unit) failure at the same time and that's why your N2's needles are going up but they should go up even if you don't pull up the collective, in fact when you pull up the collective they should drop not keep going up.

Once your N2's needles went trough 120% more or less, 122.5% to be more exact in this helicopter, your turbines should have stoped to avoid their explosion and try to keep your blades and transmision in their place and not in several piezes around the helicopter.

 

22 hours ago, flying_carpet said:

How much more realistic is this depicted in your sim of choice?

I don't have a sim of choice and I am not trying to enter in a discussion of "my sim is better than yours".

[Soul Rebel 39]

12 hours ago, Murmur said:

I've done a test myself, and the actual failure simulated in this case is, as we could call it, a "throttle runaway" (it is listed as "rotor controller failure" in the failures screen, indeed poor wording).

 

When you did your test, this affected to both engines or only one?

[Murmur 3,944]

2 hours ago, Soul Rebel said:

When you did your test, this affected to both engines or only one?

Indeed, apparently there's a limitation in this specific failure mode in X-Plane, in that multi-engine helicopters have all governors fail at the same time, when failure is enabled. So this specific failure is best used only with single engine helicopters.

Could also be something to report to Austin as a bug/feature improvement.

[flying_carpet 657]

On 8/10/2023 at 2:41 PM, Soul Rebel said:

When you did your test, this affected to both engines or only one?

Your initial post ...

On 8/8/2023 at 10:06 PM, Soul Rebel said:

That's anything but realistic.

... sounded like "that's completely wrong", what is not the case. It's indeed not completely correct for twin-turbine helos, but as I understand it, correct for single-turbine helos. So, not that far away from being realistic.

BTW, have you reported the inaccuracy? I did so for 2 other failure simulations and they were corrected.

On 8/10/2023 at 8:09 AM, Greazer said:

Probably not an XP bug but a controller issue, such as noisy rudder axis or what not. Can not blame Devs for that 😁

???

[Soul Rebel 39]

2 hours ago, flying_carpet said:

 

... sounded like "that's completely wrong", what is not the case. It's indeed not completely correct for twin-turbine helos, but as I understand it, correct for single-turbine helos. So, not that far away from being realistic.

 

It's not correct even for single engine helicopters, with an overspeed if you pull up your collective your N2 and Nr should drop not rise even more.

[Murmur 3,944]

48 minutes ago, Soul Rebel said:

It's not correct even for single engine helicopters, with an overspeed if you pull up your collective your N2 and Nr should drop not rise even more.

That's what actually happens in X-Plane.

I think the collective was not touched in flying_carpet video, N2/Nr rising is just the effect of runaway fuel flow.

Edited August 12, 2023 by Murmur

[mSparks 2,094]

39 minutes ago, Murmur said:

That's what actually happens in X-Plane.

I think the collective was not touched in flying_carpet video, N2/Nr rising is just the effect of runaway fuel flow.

agreed.

Do you know if they fixed the hydraulics?

In XP11 they were keyed off the turbines instead of the rotors.

[Murmur 3,944]

3 hours ago, mSparks said:

agreed.

Do you know if they fixed the hydraulics?

In XP11 they were keyed off the turbines instead of the rotors.

Oh, I don't know about that. I see Plane-Maker has specific entries for "rotor-driven hydraulic pump" as hydraulic sources (as opposed to engine-driven), and they're checked for the default S76.

So, provided there isn't a bug, they should be linked to rotor movement now, I guess.

[mSparks 2,094]

6 minutes ago, Murmur said:

Oh, I don't know about that. I see Plane-Maker has specific entries for "rotor-driven hydraulic pump" as hydraulic sources (as opposed to engine-driven), and they're checked for the default S76.

So, provided there isn't a bug, they should be linked to rotor movement now, I guess.

The bug was:

I think I filed it, but then forgot all about it.

nice, I was looking at the underlying systems and failures, there is individual governors for each engine and failures for individual governors. So might just be the way the failure was fired.

Apparently never uploaded this, as good an excuse as any