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Coordinated Flight/Ball

backstab

By backstab
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Nealius

Nealius

Posted
Posted

Between this discussion and my experience in the Huey recently, I'm really confused. Between 60~85kts I need:

 

Headwind: right pedal

Tailwind: significant right pedal

Left x-wind: right pedal

Right x-wind: neutral pedals; sometimes left pedal if I'm heavy

 

Really weird to me, but I'm more experienced on fixed wing than rotors. 

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fapador

fapador

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Posted

All the claims here are for no wind, or mild wind conditions. We need someone really experienced preferably an army guy to tell us if right pedal correction is necessary on high speeds above ~90knots. Also the helicopters rigging is very important it should fly like the description on the operation manual but some might be different 

Obsessed with FM's

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pbishop

pbishop

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Posted (edited)
1 hour ago, admiki said:

I know. I am talking about posts above that state you need this or that in different winds.

 

Not sure what you mean then.  There is no this or that if you could careless about the ground below you (which you mention in your question).  Control position in mach 2 wind or 10 kts wind will be the same if you are travelling in trim flight with an indicated airspeed of lets say 80 kts (regardless of the direction of the wind).


Edited by pbishop
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admiki

admiki

Posted
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1 hour ago, pbishop said:

 

Not sure what you mean then.  There is no this or that if you could careless about the ground below you (which you mention in your question).  Control position in mach 2 wind or 10 kts wind will be the same if you are travelling in trim flight with an indicated airspeed of lets say 80 kts (regardless of the direction of the wind).

 

Look at the posts on top of the page. Both posts state that you need certain pedal position for certain wind

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pbishop

pbishop

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12 minutes ago, admiki said:

Look at the posts on top of the page. Both posts state that you need certain pedal position for certain wind

 

How you interpret the discrepancy is up to you, but I have given you the answer twice.....  Take care, and cheers!

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admiki

admiki

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Posted (edited)

It looks like DCS hasn't modeled any tail fin effect in Huey. Although, even that IRL table shows you need to back off right pedal once you go over 70 knots (my guess is due to power requirements). In DCS, faster I go over 80-90, I need more power and more left pedal, but I never come even to neutral, not to mention right pedal.

@fapadorwhy do you keep coming back to wind direction? Wind direction does not have any effect on trimed flight (ground track is different story).


Edited by admiki
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admiki

admiki

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51 minutes ago, fapador said:

@admiki Wouldnt wind cause the ship to dirft or to turn into the weather requiring correction with antitorgue?

Yes if you are hovering over one spot. If you try to hover at absolute zero airspeed (moving with the wind over ground) or fly forward at any speed, aircraft do not care where the wind is blowing from.  

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pbishop

pbishop

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So this conversation got me curious so I did some work.....  I'll go through the process very briefly because I think the details are probably going to take a while to explain.

 

The following data was exported from DCS using the export.lua into a log file:

 

  arg Value
IAS 117
Rudder 184
Longitudinal Stick 186
Lateral Stick 187
Collective 200

 

The searchlight (arg value 410 on/off) was used to mark data when stable on a test point to find the data afterwards.  Stable on point was trimmed at the desired airspeed in level flight for at least 1 min.  After the minute in stable flight, the marker was turned on between 5 and 10 seconds long.

 

The average position over the data with marker on was used to plot control position.  The position values were converted from full range (+max/-min) to a percentage of the full travel.  The flight test data from the UH-1H report was then also converted to percentage to allow it to be plotted on the same graph.

 

Some notes:

The following table provides the setup between the two tests.  A difference between the two is there is no calibrated airspeed in DCS (not sure how you could correct for a simulated installation anyways) so indicated airspeed was used assuming no installation error.  A different CG chart then the one posted before is used (see end of post), as theoretically it may be closer to the CG we can simulate in DCS, slightly more forward.  No idea if long/lat CG data can be extracted, so it is N/A.

 

  UH-1H Flight Test Data UH-1H DCS Data
Gross Weight (lb) 8740 8840
CG Long (in) 132.4 N/A
CG Lat (in) 0 N/A
OAT (C) 24 24
Density Alt (ft) 5220 5100

 

Now for the interesting bit:

 

image.png

 

image.png

 

image.png

 

image.png

 

image.png

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admiki

admiki

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That is awesome man!

I will focus only on collective and pedal inputs because a)it's focus of this thread and b) cyclic position seems to be close enough to test data.

 

Even IRL, it seems that torque requirements demand more antitorque than tail fin can provide with speed increase, which ask for less right pedal. DCS exagerates this quite a lot. But, IMO, this comes from collective position. While both sets show increase, DCS set start at higher point and requires larger delta than IRL set. It would be interesting to see pedal position from same collective position in IRL data (yes, I know this would produce a climb). I don't know if torque values are pulled from the table or are actually calculated, but it seems focus of this thread might be solved just by tunning up collective.

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pbishop

pbishop

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Just to clarify, I did not post this to draw any conclusions as to the source of the problem.  I am sure the devs have certain limitations as to how the aircraft is coded and did their best to get it as close as they could.  In my opinion, there is a lot more they got right then wrong.  Helicopters are inherently complicated and taking the rotor dynamics, aerodynamic effect, etc... into account is near impossible to model without the proper data and tools.  Only they know what the issue might be or even if it is technically possible to get the sim to match closer with the data/mathematical models they have.  There is a strong possibility that by starting to play with the controls they open a can of worms they wont get out of any time soon.  I provided this just to show that there is a difference so people don't have to speculate about it and can at least accept it for what it is.  Now, if this issue is caused by this or that, or if it needs more attention, not my call.  I still enjoy the huey for what it is, a sim, and a good one.

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fapador

fapador

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Posted (edited)

For me physics/flight dynamics are the most important factor. The models should feel natural and respond realistic in a certain degree. I have done my research all these years and currently I can certainly say that no perfect rotorcraft PC home sim exists in that respect.( Yes even Xplane has problems at straight flight with weird roll issues  and lack of yaw effect and spiral wash prop modelling. There is no way  to address this even with workarounds in PlaneMaker and in the end for ME produces bad unrealistic results ). 

   Physics development, demands real research, time and resources + educated experienced  people. This returns no real value for the devs other than a nice feel and experience for the end user that has a taste for accurate physics and doesn't "fall" in the average consumer category that will never realize that something might be wrong / or question the FM. Even in some warbirds I have  doubts for their FM, or the general DCS's prop/wash/torgue model. 

   However I feel that I should mention that what astonishes me the most,  is that older  attempts such as the unprecedented Janes WWII Fighters have gotten really close in the physics  department with the tools available at the time and it still "feels" great. It was developed by EA (so perhaps they had the resources) and real aces contributed to its development just like DCS.  For ME  Janes WWII is still an unsurpassed jewel of the golden age of the Flight simulation for the PC combat sim enthusiast in that perspective so there is no reason something better more accurate cannot be achieved today.

  Now for the pedal discrepancy the source might be a collective position/ torgue issue or something in the empennage and the way it's modelled or even a wrong wash calculation. or a combination of the above. Only the creators of the FM know and ONLY THEY can address it.  

 

I know its hard and I don't mean to sound salty. As @pbishop mentioned the things they got right are BY FAR many more, but AS A CUSTOMER I want it to be addressed and so should all of us, it's an official licensed Bell product after all. 

 

PS: I wouldn't care so much if this discrepancy was on any other module But the HUEY, I totally love this Bird!


Edited by fapador
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Obsessed with FM's

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