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Left turning tendancies of DR400


Steve451

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Hi,

Regarding the left turning tendancies of the Robin. Can it be adjusted as to make it not so strong. I have flown 4 different types of Dr400 form the 108 to the 180 and none of them have had so much torque to the left. You either have right rudder or right stick pushed to the right to compensate.This is across all levels of power. The Robin's I have flown do have a slight tendancy to want to go off to the left but this is compesated by slight pressure on the stick to the right. I have tried to fly HB-HBR but this I find is still to strong.

Also could it be possible to remove that small crack in the perspex,above the instrument panel. Its really annoying.

post-63439-0-35130700-1360493999_thumb.p

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I join the question.

Hi All,

Some of us are somehow frustated with this well reproduced "defect" of Joachim aircraft. I was also.

If you want to disable it, here is a method which is working well. There is 4 files to modify (4 different models) :


\SimObjects\Airplanes\Aerosoft_DR400-140b\panel\S3DD_Robin\Robin_Sys.xml

\SimObjects\Airplanes\Aerosoft_DR400-140b\panel.adfgps\S3DD_Robin\Robin_Sys.xml

\SimObjects\Airplanes\Aerosoft_DR400-140b\panel.adfgps\S3DD_Robin\Robin_Sys_ADF.xml

\SimObjects\Airplanes\Aerosoft_DR400-140b\panel.evem\S3DD_Robin\Robin_Sys.xml

1. First, make sure you make a backup of these files ! 2. Open each one with an editor (notepad, notepad++ or other) 3. Search for the following section :

<!-- ****************************** -->

<!-- ******** P-Faktor ********** -->

<!-- ****************************** -->

<!-- (A:ENG TORQUE:1, Foot pounds) 382 / (&gt; L:Pfactor, number)	 -->

<!-- (L:Pfactor, number) (L:Pfactor_hist, number) - abs 0.05 &gt;=	 -->

<!-- if{																 -->

<!-- (L:Pfactor, number) -163.83 * 0.25 * (&gt; K:RUDDER_TRIM_SET)	 -->

<!-- (L:Pfactor, number) -163.83 * 0.065 * (&gt; K:AILERON_TRIM_SET)	 -->

<!-- (L:Pfactor, number) (&gt; L:Pfactor_hist, number)				 -->

<!-- }																	 -->

		 (A:ENG TORQUE:1, Foot pounds) 382 / (&gt; L:Pfactor, number)

(L:Pfactor, number) (L:Pfactor_hist, number) - abs 0.05 &gt;=

if{

(L:Pfactor, number) -163.83 * 0.2 * (&gt; K:RUDDER_TRIM_SET)

(L:Pfactor, number) -163.83 * 0.055 * (&gt; K:AILERON_TRIM_SET)

(L:Pfactor, number) (&gt; L:Pfactor_hist, number)

}

4. Delete the section

5. Save the file

6. Reload the Robin and try

You can also try to tweak the parameters instead of erasing the whole section... which I can't do as I don't know how it works ;-)

Hope this help...

Thanks to JardY from pilote-virtuel forum for the tips !

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Hi Roland,

And thanks for the reply. I have tried your advice a slightly different way and reduced the Robin P Factor in the aircraft config file which you can access through the notepad. It is a lot better thanks. I also reduced the engine HP from 160hp to 140hp. Which is nearer the Robin I fly. Its more like I would want it now.

Many thanks for your help

Perhaps we could have an official fix to this.

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Sorry I take that back. Its does not seem to have made a difference after all. I will try your method Roland if I can find the correct files.

Can you tell me how to get to them.

Thanks

Steve

Steve, the 4 files path are written in my post #5 up.

Path are relative to your FSX or P3D installation folder

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There will be optional files for people who don't have pedals.

Please be a little be patient. I will load them up soon.

(For everyone, who modifies his files, please don't forget to make backup copies)

The reduced power is not recommended, this does not represent the modelled plane in any way.

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Thank you for the reply Joachim,

I do use rudder pedals. My request was just for a bit less tendancy to turn to the left. Its a personal thing and closer to the Robins that I fly. I find that at the moment when navigating I am spending much more time keeping the plane on course than I would in real life.

I have mostly overcome the sensitivity issues I have and am enjoying at last a DR400 that looks and feels right (apart from the left turn tendancy).

Thanks for producing this classic aeroplane for us all to enjoy.

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as a tip, when you use pedals:

Just do not kick the ball centered, this will result in a right roll tendency ;-) Just kick it, that the plane flies more or less straight, and keep your foot there. Then you have time for the nav things. (This produces a verys slight side slip) However, for performance, you need to keep the ball centered ;-)

Bests, Joachim

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Thanks for the reply Joachim

I will try it out tonight to see if I can use the rudder more to keep the plane straight. I have left the P Factor slightly reduced in the aircraft cfg but I have taken the power back up to 160hp.

It did feel better this morning when I tried it. As said before I do have to apply some pressure to the right to keep the plane on a straight course in the actual Robins's I fly.

I am learning to like this plane a lot now. It will be my default plane for FSX.

Thanks

Steve

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First of all thank you for this plane! I was waiting for it a long time.

Two years ago I learned to fly and made my pilot licence on the HB-KFV and the HB-KFW (the cockpit looks a little different in reality but never mind)

Regarding the left tendency I can tell you, that the Robin needs a good portion of right foot at start, less at climb and none at cruise

Why? There is a little fin at the rudder to trim away the left tendency. on ground you just bend it a little bit towards the direction needed and it works well

Therefore the individual left tendencies are related to this small fin

@Joachim: right now it seems that the left tendency is indipendent of the altitude and quite strong (even in the HB-KBR). It would be nice if you could decrease the left tendency a) in general, B) with increasing altitude, c) with increasing speed and d) with increasing temperature

Thank you for this great plane

Kind Regards

Dirk

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Well, as you can see on the external model, none of the released Robin have a trimtab on the rudder.

That is, why it definitely needs right imput even in cruise flights. Belive me, I know the plane VERY well ;-)

Of course planes equipped with that little tab are different. The KFV might have one, so I can't say, you're wrong. But the KFV is not the reference model (so the panel does not fit exactly as well)

However, I will release some files, which make the Robin more "straight flying" even if it does not represent the reference airfiles. :-)

(Intended for non pedal users)

Bests, Joachim

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Joachim

I'm not offending you and I'm shure you know the D-EVEM at least as good as I know the HB-KFV

At least regarding the left tendency the EVEM seems a little bit special as reference due to the repaired wing

Therefore reducing (not eleminating) the left tendency to a common level at some of the other planes would be a nice move for the ones who are not used having to press the rudder for the whole flight

Kind regards and again thank you for your great work creating this plane and beiing patient with customers like me :bow_down2_s:

Dirk

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Dirk, I didn't take that as offense! So Everything fine :-)

Hmm, the repaired wing has almost nothing to do with the left tendency. As you can see on the turn and bank indicator, it is mostly the cork screw effect, which causes the issue.

Thats why it could be eliminated or at least greatly reduced by using a trim tab.

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Hi Joachim

I think all we are asking for is a reduced amount of torque. I like others use rudder pedals and would just like to be able to fly the Robin as we are used to flying it.

Its an excellent plane for FSX, one we have been waiting for. Its the first FSX plane that I have spent so much time trying to get it just right. That says to me how good it is.

Your backup is excellent, and I Thank you for that.

Best regards

Steve

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Maybe not the totally right topic for this question, but how do you describe the pitch change with flaps? I tried to fly straight, level and with constant speed (which is not quite easy :) ), then I set flaps to step 1, speed decreases but there is no significant lift increase. The VSI and the "Popometer" stay more or less level. I know, most FPS planes suffer from an overdone lift factor, but also I know from the Piper Archer III and Cessna 152 that you have to push the stick in this situation (setting flaps step one). Full flaps also create additional drag with just a minor nose-up tendency. I know, you designed the Robin from real world experience so I am convinced, this is totally correct in our FSX Robin. I am curious to know how you handle/feel pitch changes due to lift/drag effects of the two flap settings in the real thing.

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Well, as you can see in the 3d model, the flaps are VERY small compared to any Cessna or Piper.

Flaps 1 gives a little whoop in real life, nothing serious, flaps 2 again some kind of whoop, but much more drag than lift.

Flaps produce a little nose up moment, but this more or less gets eliminated by the resulting loss of speed.

I am also not sure if flaps1 does really help on short take offs :D Manual says yes...

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This may be academic since there may be a fix out by the time I finish typing, but for those like myself with

no foot pedals and a strong joystick spring, one quickie fix for the left turn tendency is to move the pilot's

weight towards the co-pilot's side of the plane. This will somewhat counter balance the left turn tendency.

In effect, it's like taking my 300 lb cousin for a ride.

In the airplane .cfg, under load stations, the default values for the pilot's station_load.0 are

"200.0, -0.50, 0.0, 1.0". I changed the "0.0" to "1.24", so I now had "200.0, -0.50, 1.24, 1.0".

For the F-BAI model, I found this now produced a slight right turning tendency, instead of left turning.

So I reduced the pilot's weight down to 185, and this kept the plane on a reasonably straight course

with occasional corrections. Other models might require different weight fixes.

It's not a perfect fix; you are flying at a bit of a tilt, and the plane is on a bit of a knife edge, so you will still

need occasional corrections, but it does let me fly without having to continually fight the joystick spring.

I mentioned this in another thread, but thought I would mention here too, since it works for me, and might

maybe help someone else, until a proper fix is in place.

Thanks - Rob

PS: I guess, you could try to split the difference between 1.23 and 1.24 so you wouldn't have to change

the weight, but I've never seen a placing setting out to three decimals in the load stations, only to two decimals,

so I didn't know if FSX would take those. And also I find it's much easier to fine tune by changing the pilot's weight.

PSS: in case someone asks, because all load stations are on the center line in this plane, you can't do a fix by

simply adding a passenger or baggage weight on the right hand side.

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Flapless takeoffs are perfectly possible in the Robin, the only real reason to use Flap 1 is for reduced runway distance which can be handy on wet or muddy strips. I've never used flaps in a real Robin on tarmac for takeoff. You might if it was a taxiway, and you were across it... :chairfall_s:

Lift is not an issue with the Jodel-style wing, so the flaps have little lift effect - and in first stage very little drag either. It's more about the wing-in-ground-effect for an earlier unstick.

The aim for landing is to get flaps 2 (full flap) down as soon as possible (same 170 km/h limiting speed as Flaps 1) as otherwise the Robin is very slippery and can be difficult to slow, even with quite dramatic power reductions

Conversely after landing the aim is to get flaps up as soon as possible - keeping the nosewheel high provides aerodynamic braking.

One thing that the Robin is noted for is slightly nervous behaviour in a crosswind - I was taught the `French Way` (French airfields typically only have one runway so there's more exposure to crosswinds, and this ties in nicely with an FSX technique that applies to all nosewheel aircraft in the sim - after landing when the nosewheel touches you move the stick to a slightly nose-down elevator position, slightly forward of centre to reduce the `nervous` feeling.

The same technique works with all FSX tricycle GA and improves ground handling and steering.

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