ETL Vibration

[HuggyBear]

It's been stated repeatedly by devs and testers that the ETL vibration animation is exaggerated, this is a design decision made by the dev team to account for the limitation of PC sim hardware/interface.

 

Real-life ETL creates a shudder throughout the airframe which is clearly felt by the crew. It is a helpful indication to the crew of the slowest speed they can make an approach, without dropping below ETL and requiring a large abrupt increase of power.

 

'Riding the burble' (maintaining airspeed on the edge of ETL) is one of the more important aspects of an approach when you are power-limited and operating to an unprepared or confined LZ.

 

It shouldn't matter a great deal that your instrument panel is vibrating, your vision should be directed toward your intended landing point, your instruments are largely irrelevant at this stage.

 

- Bear

[IonicRipper]

Can't the effect can be reduced without completely loosing it?

[HuggyBear]

Definitely, that's why these beta forums are great. :)

 

I believe it will be adjusted to a more reasonable level without compromising it's usefulness.

 

- Bear

[Golo]

If I may I want to point to another kind of exaggerated effect and that is ground oscilation when starting and shuting down the engine.

I watched countless vids of huey starting up an other helis IRL and never saw this effect been so obvious.

This is in no way extra important for fixing, just pointing out my opinion.

[Rongor]

What does ETL mean?

[Golo]

^Effective translational lift

 

http://www.dynamicflight.com/aerodynamics/translational_lift/

Edited July 4, 2013 by Golo

[pbishop]

It's been stated repeatedly by devs and testers that the ETL vibration animation is exaggerated, this is a design decision made by the dev team to account for the limitation of PC sim hardware/interface.

 

Right........

I still don't understand why the shudders are so exaggerated throughout the full flight envelope. There are limits, and that is what I was referring to. I can live with the effect at takeoff, even if its more of a cosmetic feature, but why is it still present while cruising along. If the dev team feel limited by the hardware/interface of the PC, they should still be open to constructive feed back on their design choices. I also think they can do better.

 

Also, I'll decide what is relevant to me for myself. Thanks.

Edited July 4, 2013 by pbishop

[Golo]

Right........

I still don't understand why the shudders are so exaggerated throughout the full flight envelope...

 

There are no vibrations (or almost none) after you get past ETL transition.

I guess you are refering to vibrations during cruise at speeds over 100kts. If that is true it has to do with different effect and that is retreating blade stall

and it is as it should be as far as I can tell.

[pbishop]

There are no vibrations (or almost none) after you get past ETL transition.

I guess you are refering to vibrations during cruise at speeds over 100kts. If that is true it has to do with different effect and that is retreating blade stall

and it is as it should be as far as I can tell.

 

I am going to start off by saying that I need no explanation on helicopter flight, aerodynamics, control systems, etc...., and I'm going to leave it at that.

 

I am referring to the fact that no matter what phenomena someone here wants to put a label on, the panel shakes to point of being ridiculous (especially when you notice it does not seem to be attached to the rest of the helicopter when it does so). And I could imagine they were trying to simulate retreating blade stall, ground effect, starting the engine, opening the doors, or sneezing the wrong way by simulating how someone who has a seizure feels. The helicopter shakes off the ground when you start it..... there is a problem. I don't think the game should look like you are playing it through a camera being held by someone in the helicopter, and if the source of info was from an actual pilot, they would tell you the same thing I have said here, it is excessive.

 

On another note, the helicopter does fly pretty well in real life, hence why it has survived so many generations. The thing is a mess right now by trying too hard to simulate all these things to a point where you are no longer flying the helicopter, you are simply getting some artistic impression of whats going on. Agree or disagree, I could careless. Comparing with the real thing, I can tell someone was trying too hard here to show the flight sim community what was going on.

 

Don't get me wrong, the real thing shakes, but not this bad and after a while you don't notice it, so why simulate it at all? The impression something is happening? Give it with a toned down version, ie. when an aircraft stalls in cliffs of dover style is ample in magnitude compared to this, and for the love of ... attach the instrument panel to the rest of the helicopter.

 

EDIT:

 

This is what it feels like right now (between 5 and 10 sec)

Edited July 4, 2013 by pbishop

[HuggyBear]

...Also, I'll decide what is relevant to me for myself. Thanks.

 

If you feel your instruments are particularly relevant in the final stages of an approach them my posts are not directed toward you. :)

 

Despite your implied experience, the real thing shakes during start, shakes through ETL and shakes approaching VNE,

 

As previously stated, it's currently exaggerated but it's being tweaked.

 

- Bear

[pbishop]

If you feel your instruments are particularly relevant in the final stages of an approach them my posts are not directed toward you. :)

 

Despite your implied experience, the real thing shakes during start, shakes through ETL and shakes approaching VNE,

 

As previously stated, it's currently exaggerated but it's being tweaked.

 

- Bear

 

No problem, for the first part, its mostly in flight i was referring to, although i couldn't find a topic else where that discussed the shake. (IFR)

 

As for takeoff i know, but the version in game currently lifts off the ground, which is odd.

 

and for the the exaggerated bit but being fixed, thats what I was looking for, thanks. And have fun:thumbup:

[TimeKilla]

If you feel your instruments are particularly relevant in the final stages of an approach them my posts are not directed toward you. :)

 

Omg I almost fell off my chair. :megalol:

[HuggyBear]

No problem, for the first part, its mostly in flight i was referring to, although i couldn't find a topic else where that discussed the shake. (IFR)

 

You want to take a Huey into clouds? Madness! :)

 

The inflight/cruise instability is also being adjusted, although IFR in a Huey is still a pain in the arse, as it should be.

 

- Bear

[pbishop]

You want to take a Huey into clouds? Madness! :)

 

The inflight/cruise instability is also being adjusted, although IFR in a Huey is still a pain in the arse, as it should be.

 

- Bear

 

Couldn't agree with you more, they did a good job there. Also glad to hear they are adjusting the instability in flight, thanks for all the info.

[Rogue Trooper]

I think it works great as it is, the shaking gives a visual feedback that is useful.

[hansangb]

I think it works great as it is, the shaking gives a visual feedback that is useful.

 

Agreed. I need all the help since there is no physical feedback. Saves me from VRS quite a bit too.

[nemises]

I guess it's a personal preference..I like it shakey as it means I don't need to look at my Air speed indicator to know where I am in the envelope. Sure, the effect could be less visusally , and still useful I'm sure, so there you go.

beta is beta

[jay43]

I too like the shakes it gives that nudge, hey you if ya don't pull on that CP we are going down.

Could do with toning down just a tad not to much I feel it can sometimes be a little aggressive on you and feels like the whole thing is about to implode on you in mid air.

[pbishop]

I too like the shakes it gives that nudge, hey you if ya don't pull on that CP we are going down.

Could do with toning down just a tad not to much I feel it can sometimes be a little aggressive on you and feels like the whole thing is about to implode on you in mid air.

 

Although I agree its useful as a visual cue, it makes it nearly impossible to fly in fog or poor visibility. And, even though most people here have use for it when flying visually, it makes more advanced missions in poor weather very difficult. What a lot of people don't think of on these forums is that just because the conditions you fly in (bright sunshine and rainbows) works for you, applying the same thing in different conditions such as rough weather or low vis night does not work so well when instruments are an essential part of flying. Because you are not alone, and not everyone flies in the same way, it is important that it caters to everyone, and also having the dcs brand be a believable sim. As all of you seem to be saying the same thing I have, its excessive, at no point did I say remove it, just tone it down to a point that is more believable and to a point that works for all regimes of flight so that we can actually use the instruments and have something a bit more believable; less of a dramatic effect and more of a sim product capable of living up to the dcs name.

[Rangi]

I have no problems with reading instruments while the console is doing its wiggle dance and appreciate the extra feedback to replace the physical sensations I don't get from my chair. So I would prefer a high and low selector in options than just turning it down/off for everyone.

 

Hope this reads ok, makes sense, bit drunk.

[flyer49]

I have over 2000 hours in the UH-1H and have seen and heard (you can hear it) the vibrations that accompany the transition to forward flight. The vibrations are not as pronounced or as prolonged as they appear in the DCS version but I just take this as they're attempt to show that it exists and can be felt in the seat of your pants. There is little to no vibration in the controls and the thing that I miss most is the slight dip that the airframe makes during the transition. To me, this dip indicated the transition from hover to forward flight while going through ETL. Below is a short tutorial of the ETL aerodynamic effect. I hope it help...

 

 

Translational lift

 

The efficiency of the hovering rotor system is improved with each knot of incoming wind gained by horizontal movement or surface wind. As the incoming wind enters the rotor system, turbulence and vortexes are left behind and the flow of air becomes more horizontal. All of these changes improve the efficiency of the rotor system and improve aircraft performance. Improved rotor efficiency resulting from directional flight is called translational lift. Air flow patterns will start to change between 1-5 knots,

 

The downwind vortex will begin to dissipate and induced flow down through the rear of the rotor disk is more horizontal than at a hover. Airflow pattern at a speed of 10-15 knots is much more horizontal than at a hover. The leading edge of the downwash pattern is being overrun and is well back under the helicopter nose. At about 16 to 24 knots (depending upon the size, blade area, and RPM of the rotor system) the rotor completely outruns the recirculation of old vortexes, and begins to work in relatively clean air:

 

The air passing through the rotor system is nearly horizontal, depending on helicopter forward air speed. As the helicopter speed increases, translational lift becomes more effective and causes the nose to rise, or pitch up (sometimes called blowback). This tendency is caused by the combined effects of dissymmetry of lift and transverse flow. Pilots must correct for this tendency in order to maintain a constant rotor disk attitude that will move the helicopter through the speed range where blowback occurs. If the nose is permitted to pitch up while passing through this speed range, the aircraft may also tend to roll to the right. When the single main rotor helicopter transitions from hover to forward flight, the tail rotor becomes more aerodynamically efficient. Efficiency increases because the tail rotor works in progressively less turbulent air as speed increases. As tail rotor efficiency improves, more thrust is produced. This causes the aircraft nose to yaw left if the main rotor turns counterclockwise. During a takeoff where power is constant, the pilot must apply right pedal as speed increases to correct for the left yaw tendency.

 

References: Copter .com, Army TM 55-1520-210-10 and Army TM 1-203

 

Edited July 13, 2013 by flyer49

[Griffin]

In my opinion the ETL vibration is way over the top in DCS currently. I don't find issues with controlling the aircraft at all despite my flying being really bad with so low hours. I don't mind the ETL vibration as long as it's realistic. So it's not a problem with the flight model itself. Several professional helicopter pilots have said that the current situation is not realistic at all. The seat of the pants effect can be achieved with less than half of the vibration present currently without sacrificing the "feel".

Currently I find it the biggest problem in my approach to hover transitions. It takes away too much of my concentration to get out of the insane shake. I know I can overcome it with practice but if it's already deemed unrealistic, why have it there.

I certainly hope it will be reduced in the final version.

 

PeterP, heard anything about the video?

 

Here's the best video I could find from inside the cockpit. Not this or any of the worse ones give you any visual ETL shake in transitions. In fact, the shaking gets worse with the increase in speed. Again, I don't mind having a visual shake to try to simulate something you could feel with your arse but the supposedly helpful shudder in your bottom has been transformed into an earthquake that's about to rip the instrument panel out of the window.

 

Starting at 4:45.

[jay43]

I barely get the shakes anymore but I have put in a lot of hours like the video though nice find.

The thing I hate is the weakness of the skids as Huey pilots in nam would over load the Huey and to take off they would lift the collective and drop it forcing the Huey to bounce on the skids to get the air cushion of hover effect under it to create more lift and keep slaming the skids into the ground until they had enough lift to get airborne. If that makes sense was on the Discovery channel a whole hour on the Huey.

When I try this the skids just break away after a couple of attempts.

Edited July 15, 2013 by jay43

[AlphaOneSix]

to take off they would lift the collective and drop it forcing the Huey to bounce on the skids to get the air cushion of hover effect under it to create more lift and keep slaming the skids into the ground until they had enough lift to get airborne. If that makes sense was on the Discovery channel a whole hour on the Huey.

When I try this the skids just break away after a couple of attempts.

 

This is wrong on so many levels.

 

Of course the skids will just break.

[flyer49]

I've never heard of Vietnam pilots bouncing an aircraft form a hover but I don't dought it. They were know to use a lot of unique techniques to fly the earlier UH-1's. The A/B/C models were underpowered and I have talked to a few Vietnam era pilots and had them tell me that they would sliding down a runway (sort of a running takeoff but with skids) throwing cargo out until they achieved sufficient airspeed and weight for takeoff. It would seem that if they can achieve a hover then they have enough power for takeoff...I'd love to see this episode.

Edited July 15, 2013 by flyer49