Nose Heavy?

[jayeye2011]

I know this still is WIP, but seems a bit nose heavy requiring 100% up trim and 80 to 100% power with speed in yellow zone.

[krzysk1]

I am finding a flight model of this aircraft for a complete rebuild, I will be doing it soon. Thanks for remark

[jayeye2011]

Although I somewhat understand X-Plane 11 in regards to how to tweak an aircraft acf file using its Plane Make tool, I have no idea how one can adjust flight characteristics in Aerofly, The Optica is a pretty good one to have available in Aerofly FS 4 so I hope it all works out.

On Sat, Dec 3, 2022 at 12:06 PM Krzysztof Kaniewski < @.***> wrote:

I am finding a flight model of this aircraft for a complete rebuild, I will be doing it soon. Thanks for remark

— Reply to this email directly, view it on GitHub https://github.com/krzysk1/optica/issues/2#issuecomment-1336249183, or unsubscribe https://github.com/notifications/unsubscribe-auth/AQQ2UNTQPSXYJMRYCXDOVETWLOR5PANCNFSM6AAAAAASSYXHJQ . You are receiving this because you authored the thread.Message ID: @.***>

[jayeye2011]

Correct me if I am wrong, but the flight model is what Aerofly FS 4 simulation provides, and is what generates the physical responses in flight using the aerodynamic specifications of the airplane model as provided in the optica.tmd file. So you just need to figure out what to change in the tmd file having to do with aerodynamic specifications. Since the copilot automation seems to be able to fly the Optica straight level without an issue except for the 100% up trim being required I would imagine that this is mostly what needs to be adjusted for the casual level of flight simulation accuracy that Aerofly FS conforms to. If it was X-Plane of that would be a different matter since then you would need to match the certified flight performance of the actual real-life aircraft, but fortunately that is not required here. Allthough I don't know how Aerofly determines this (via in flight computation or tmd file specifications) it seems to me that the need for excessive level of elevator trim to maintain level flight can be caused by the following in order of most likely to least likely.

1. The aircraft center of gravity (CG) has been set too far forward of the aircraft center of lift (CL). So I would try moving the CG back in incremental amounts and see if this helps somewhat (while trying to avoid generating a porpoising dynamic instability)
2. Check the horizontal stabilizer specification because too much lift from the horizontal stabilizers can cause a nose down condition. This can because of a) wrong airfoil type b) wrong stabilizer size specified c) wrong incidence angle.
3. Unlikely, but finally check the main wing specification for incidence angle as this can alter the lift vector but again this is least likely. I think porpoising may result from a conflicting interaction between main wing and horizontal stabilizers caused by unsuitable incidence angles for main wing and horizontal stabilizers. Anyway, I don't know how this all is specified by Aerofly, but its very easy to tweak and test in X-Plane via its Plane Maker tool. Too bad IPACS does not provide something like that in its SDK. EDIT: I forgot, it also possible that the elevator trim specification does not provide enough trim authority, this could be because of either insufficient angular deflection limits or because the trim/control surface area is not large enough.

[jayeye2011]

If this helps, you can download a copy of the FAA Type Certificate for the Edgley Optica here https://drs.faa.gov/browse/excelExternalWindow/5376BD0E069FB7BF862579B300716F59.0001

[jayeye2011]

I was looking at the optica.tmd file trying to see where Aerofly FS defines CG, after reading the description for rigidbody and I noticed this line that defines the IntertialLength for the fuselage <[rigidbody][Fuselage][] <[float64][Mass][320.3]> <[tmvector3d][InertiaLength][-5.08 1.6 1.6]> <[tmvector3d][R0][0.45 0 0.05]> <[tmmatrix3d][B0][1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]>However -5.08 does not make sense because that is supposed to be the length of the fuselage in meters which has to be a positive value (it is not a position, just a dimension). So think this sections should be changed to <[rigidbody][Fuselage][] <[float64][Mass][320.3]> <[tmvector3d][InertiaLength][5.08 1.6 1.6]> <[tmvector3d][R0][0.45 0 0.05]> <[tmmatrix3d][B0][1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]>

[krzysk1]

-5.08 was by mistake but.. it doesn;t matter:D Aerofly takes absolute values for lengths

It can be easy to move CG but another things may go to worse. In that case moving CG to the back makes full flaps unusable. I need to rebuild the whole balance of this aircraft. Main wing and horizontal stabilizers incidence should be checked. and the trim eficiency must be checked as well

[jayeye2011]

Yeah, I hear you man. It is a complicated and interrelated mess to deal with. The flaps CL,CM,CD need looking at also because deploying the flaps can cause extreme nose up too. Also, it seems like the flaps have 4 positions (counting the fully retracted position) which is unusual, but no POH so who knows. Looking in the 3D cockpit, the elevator trim indicator between the seats has a TO and VA marker, but to get the indicatore to the TO position requires a lot of down trim which seems odd, assuming TO stands for Take Off. Another consideration is that pusher prop planes can pitch down or pitch up based on the engine power setting which makes it harder to figure out the correct incidence angles that allow for level flight within some acceptable elevator trim range. It will be pretty cool though, once you get this all ironed out.

On Sun, Dec 4, 2022 at 12:18 PM Krzysztof Kaniewski < @.***> wrote:

-5.08 was by mistake but.. it doesn;t matter:D Aerofly takes absolute values for lengths

It can be easy to move CG but another things may go to worse. In that case moving CG to the back makes full flaps unusable. I need to rebuild the whole balance of this aircraft. Main wing and horizontal stabilizers incidence should be checked. and the trim eficiency must be checked as well

— Reply to this email directly, view it on GitHub https://github.com/krzysk1/optica/issues/2#issuecomment-1336507885, or unsubscribe https://github.com/notifications/unsubscribe-auth/AQQ2UNRFIWBFKRSNJLGA2Y3WLT4CPANCNFSM6AAAAAASSYXHJQ . You are receiving this because you authored the thread.Message ID: @.***>

[jayeye2011]

Optica Data sheet FLY.pdf

[jayeye2011]

According to Wikipedia the Edgley Optica uses a NASA GA(W)-1 airfoil, so here Airfoil Tools links http://airfoiltools.com/airfoil/details?airfoil=ls417-il http://airfoiltools.com/polar/details?polar=xf-ls417-il-1000000

[jayeye2011]

Could this be the problem? The following information is from the Edgley Optica Data sheet:

"Wing chord: basic, constant 1.32 m (4 ft 4 in) over 10° fixed flaps 1.45 m (4 ft 9 in) "

"A low wing loading, fixed inboard slotted flaps and generous outboard flaps give the Optica a low stalling speed for slow speed observation and a good short field performance."

This is confirmed by the Buckarooshangar Flightgear Optica version readme https://www.buckarooshangar.com/flightgear/Optica_readme.html which states

"The inboard wing sections feature flaps fixed at 10 degrees. These cannot be adjusted in flight. Outboard flaps can be moved to as much as 50 degrees using a control on the throttle quadrant (between the seats). Optica flap movement has no detents; there are no fixed settings. Note that some Opticas could deploy flaps to no more than 40 degrees-- my guess is that these were likely the early models with the less powerful 150 or 180 HP engines."

It seems to me that if the fixed 10 degree flap section is included in the TMD file separate from the moveable fowler? flaps this would correct the 100% up elevator trim. EDIT: Since a POH is not available, the FlightGear simulation wiki on the Edgley Optica might be useful since it is done by flight simulation enthusiasts trying to accurately model correct aircraft flight dynamics. https://wiki.flightgear.org/Edgley_Optica

[jayeye2011]

Here are some pictures I found on the internet that show the inboard 10 degree fixed flaps

[krzysk1]

Here are some pictures I found on the internet that show the inboard 10 degree fixed flaps

good point. I'll set it

[jayeye2011]

Wing and Horizontal Stabilizer incidence angles seems a bit odd. <[aerowing][LeftWingAero][] <[float64array][StationIncidence] [ 0.0 -0.02618 -0.0523 ]> <[aerowing][RightWingAero][] <[float64array][StationIncidence] [ -0.0523 -0.026 0.0 ]> <[aerowing][LeftStabilizerAero][] <[float64array][StationIncidence] [ 0.034 0.034 ]> <[aerowing][RightStabilizerAero][] <[float64array][StationIncidence] [ 0.034 0.034 ]> It seems like the wing incidence and horizontal stabilizer incidence are trying to induce the same thing which is less lift from the wings due to negative AOA while the stabilizers are forcing the tail up. This what is causing the excessive nose heavy condition requiring the use of 100% up trim in level cruise flight with flaps 0. Maybe the flaps need the Cm to be more negative so you don't need to use so much incidence angles and maybe allow you to zero out either the wing or horizontal stabliizer incidence angle. Normally if you needed both wing and horizontal stabilizer to have this configuration during level flight maybe your wings are generating too much lift although that is not the case here since you need 100% plus elevator up trim. Edit: I am not a real life pilot or aerodynamics engineer so this could all be nonsense to you.

[jayeye2011]

Here is another magazine article https://www.iaopa.eu/mediaServlet/storage/gamag/apr09/p26-29.pdf

[jayeye2011]

Also noticed use of [span] and [area] parameters in aircraft.tmd.[aeroWing][] which are a) not defined for AerofFly FS 4 tmd aeroWing component file format, ([area] only used for jet engines and air brake) and none of the default affs4 aircraft has these defined in their aeroWing blocks. b) the optica.tmd left+right inner+outer aeroWing [area] you specified total only sums to 14.456 m2 vs optica 15.84 m2 per wikipedia c) I suspect that the actual area is calculated using the StationLE, StationTE, and StationY values, so if these are wrong the the wings surface area is going to be wrong also. If you are determining these values using a image you got from the internet like a scaled 3 view line drawing then try using this free tool to get the measurements more accurately. http://www.markus-bader.de/MB-Ruler/index.php

[krzysk1]

[span] and [area] are not used in AFS2 and AFS 4, and can be removed

[jayeye2011]

I suggest rather than define a separate [airfoil][AirfoilRoot][] and [airfoil][AirfoilTip][] you define only a [airfoil][NASA-LS417 ][] based on the data for Reynolds # 1M Ncrit 9 polar graphs and reference that for the aeroWing blocks. Austin Meyers did these videos explaining how to use airfoiltools.com data which you should look at if you have not seen them already. The last video is XPlane specific but may have some general nuggets of wisdom so might still be worth watching. https://www.youtube.com/watch?v=UgGIF2QkWWM&list=PLrSIPdSiSFsw0nR283R_5NDrbeVnHbnAq&index=1 https://www.youtube.com/watch?v=DmkuqJuFwWI&list=PLrSIPdSiSFsw0nR283R_5NDrbeVnHbnAq&index=2 https://www.youtube.com/watch?v=F1cj2_f9gtM&list=PLrSIPdSiSFsw0nR283R_5NDrbeVnHbnAq&index=3

[jayeye2011]

3 view drawing from sharkit https://www.sharkit.com/sharkit/optica/img330.jpg

[jayeye2011]

@krzysk1 What about using some washout from 5 degrees at root to 0 degrees at tip on the wing incidence angle like this: <[aerowing][LeftWingAero][] <[float64array][StationIncidence] [ 0.087 0.061 0.035 0.000 ]> <[aerowing][RightWingAero][] <[float64array][StationIncidence] [ 0.000 0.035 0.061 0.087 ]> This seems to let you have zero elevator trim at 105 knots

Here is the tmd file to try out

5to0 degree washout optica.tmd .zip Edit: This is based on the current December 28, 2022 optica github files Edit 2: Actually, this is no good because the Optica should have a cruise speed of 81mph or 70 knots. With this configuration you would need a lot of nose up trim or flaps to fly at 70 knots. Also, the Optica should be able to fly at 45 knots with 20 degrees flaps. So something else need to be adjusted, like maybe fuselage drag, weight, center of gravity. Edit 3: I added up all the mass units in the tmd file and it came to 1130 kg. According to the Optica.UK https://www.optica.co.uk/Optica%20Tech%20Specs.html empty wt is 2090 lb = 948 kg max wt is 2,900 lb = 1315 kg So the total aircraft weight seems okay. This means that the wing is not generating the required amount of lift for some unknown reason. Either the airfoil spec is wrong, or the total wing surface area is wrong. I don't think drag is an issue because engine power is only 46% and there is an overspeed rather than under cruise speed issue. The spec has wing area = 170 sq ft = 15.7935 sq meters <[aerowing][LeftWingAero][] <[string8][Body][LeftWing]> <[float64][Span][6.000]> <[float64][Area][8.400]> The Span and Area parameters are no longer used. I believe the wing surface area is calculated from the StationY, StationLE, and StationTE array values. Per the FLY.pdf document Wing span 12.00 m (39 ft 4 in) Wing chord: basic, constant 1.32 m (4 ft 4 in) over 10° fixed flaps 1.45 m (4 ft 9 in) Wing aspect ratio 9.09 The tmd wing dimensions <[float64array][StationY] [ 0.000 1.798 3.595 5.992 ]> <[float64array][StationLE] [ 0.455 0.440 0.425 0.405 ]> <[float64array][StationTE] [ -1.045 -1.000 -0.955 -0.895 ]> So is the Optica wing narrower at the tip than the root or is it actually a constant chord Hershey bar style wing" Here is a scaled drawing from ModelPaintSolutions.com https://modelpaintsol.com/reviews/avis-72-edgely-optica-72026 Edit4: Thinking about it, the wing dimensions while not perfect (staionLE should have the same values since wing LE is straight, likwise wing TE is straight except the span where the fixed flap is attached has a slightly wider chord) seem generally correct. There for the airfoil seems to be the issue. Looking at the airfoil without going through and trying to calculate actual values from the airfoiltools.com data for the wing airfoil there is something thing seems off just at a glance. <[airfoil][AirfoilRoot][] //NASA LS1-0417 CHECK IT <[float64][Cl0][0.0]> <[airfoil][AirfoilTip][] //NASA LS1-0417 CHECK IT <[float64][Cl0][0.0]> Per the wiki "Cl0 The Cl0 parameter increases the lift coefficient when the angle of attack is zero. This is achieved in real life by giving the airfoil a camber. For symmetrical airfoils Cl0 always equals 0.

This attribute directly reflects the attitude in which an aircraft flies at high speed (low AOA). It also requires a larger down force from the horizontal stabilizer which increases the drag. It greatly affects the glide ratio. 0.3 is usually a good value to start with. Jets tend to have lower values around 0.1 whilst slow flying airplanes have values up to 0.45. Inverted airfoils have a negative Cl0 and symmetric airfoils have a Cl0 of 0.0." So when AOA (alpha) is zero, the wing that has a camber generates lift. A value of zero only applies to symmetric airfoils used for horizontal and vertical stabilizers. The LS1-0417 should have a significant camber because it's function is to generate a lot of lift at zero AOA. Exactly what the correct Cl0 value is should determined from the NASA plot but it should not be a zero value. Here is a pdf of the airfoiltools plot for the airfoil (note the CL vs Alpha polar plot)

NASA_LANGLEY LS(1)-0417 (GA(W)-1) AIRFOIL (ls417-il).pdf The relevant polar plots are Cl vs Alpha, Cd v Alpha, and Cm vs Alpha

Edit 5: Eyeballing the three polar plots I come up with the following for airfoil parameters Cl0, CD0, CM0 <[float64][Cl0][0.6]> <[float64][Cd0][0.0075]> <[float64][Cm0][-0.0118]> Since this changes the airfoil performance, it will mean retuning wing incidence angles, fuselage drag what have you.

[jayeye2011]

Tried the following settings Airfoil (root & tip) <[float64][Cl0][0.55]> <[float64][Cd0][0.0075]> <[float64][Cm0][-0.12]> Fuselage Cdx <[float64][Cdx][ 0.65 ]> LeftWingAero <[float64array][StationIncidence] [ 0.08726 0.08726 0.08726 0.08726]> RightWingAero <[float64array][StationIncidence] [ 0.08726 0.08726 0.08726 0.08726]> Only looked at getting level flight cruise around 70 kias. Found that fuselage drag mostly determines what engine throttle setting is required. The wing incidence and airfoil parameters determine at what the level flight cruise speed is. Here is the tmd file used: optica.zip Here is what it looked like

[jayeye2011]

So basically you need to determine what power vs cruise speed, max weight climb rate you want to replicate. Since there is no POH that is hard to determine as internet sources vary. Examples https://aeropedia.com.au/content/edgley-optica-scoutmaster/ http://all-aero.com/index.php/45-planes-d-e-f/3212-edgley-ea7-optica But the constant is the airfoil spec Cl0, CM0, CD0 since that is defined by NASA although based on visual interpolation of the plots. What you can vary seems to be fuselage drag Cdx and wing incidence angle and maybe horizontal stabilizer incidence angle to achieve the desired flight envelope. That is assuming you are satisfied with your wing dimensions, wing position placement, engine specs, engine position, propeller specs, propeller position and orientations, and pretty much everything else. Very complicated and requiring a lot of trial and error via numerous test flights. Fortunately Aerofly FS does not model temperature and air density/pressure effects so somewhat less variables involved.

[jayeye2011]

This seems odd, flaps looks non symmetrical
<[aerowing][LeftWingAero][] <[uint32array][StationFlap] [ 0 2 1 0 ]> <[float64array][StationFlapFraction][ 0.00 0.30 0.30 0.00 ]>

        <[aerowing][RightWingAero][]
            <[uint32array][StationFlap]         [ 1 2 0 0 ]>
            <[float64array][StationFlapFraction][ 0.30 0.30 0.00 0.00 ]>

EDIT: NEVER MIND - I READ THE INSTRUCTION ON MIRRORING SO I GUESS THIS IS CORRECT

[jayeye2011]

Another iteration (with flap area defined for right wing) <[aerofuselage][FuselageAero][] <[float64][Cdx][ 0.3 ]>

        <[airfoil][AirfoilRoot][] //NASA LS1-0417  CHECK IT
            <[float64][Cl0][0.55]>
            <[float64][Cd0][0.0075]>
            <[float64][Cm0][-0.12]>

        <[airfoil][AirfoilTip][] //NASA LS1-0417  CHECK IT
            <[float64][Cl0][0.55]>
            <[float64][Cd0][0.0075]>
            <[float64][Cm0][-0.12]>

        <[aerowing][LeftWingAero][]
            <[string8][Body][LeftWing]>
            <[string8][Flap0Control][ServoLeftAileron.Output]>
            <[string8][Flap1Control][ServoFlaps.Output]>
            <[float64array][StationY]           [ 0.000 1.798 3.595 5.992 ]>
            <[float64array][StationLE]          [ 0.455 0.440 0.425 0.405 ]>
            <[float64array][StationTE]          [ -1.045 -1.000 -0.955 -0.895 ]>
            <[float64array][StationZ]           [ -0.090 0.004 0.098 0.224 ]>
    <[float64array][StationIncidence]   [ 0.0698 0.0698 0.0698 0.0698 ]>
            <[uint32array][StationFlap]         [ 0 2 1 0 ]>
            <[float64array][StationFlapFraction][ 0.00 0.30 0.30 0.00 ]>
            <[float64][AspectRatioMultiplier][2.0]>
            <[string8][AirfoilRoot][AirfoilRoot]>
            <[string8][AirfoilTip][AirfoilTip]>
            <[float64][Flap0Area][0.300]>
            <[float64][Flap1Area][0.300]>
            <[string8][DownWashInput][LeftWingAero.DownWashMean]>
            <[float64][DownWashPercentage][1.00]>
            <[float64][GroundEffectFactor][1.00]>
            <[float64][GroundEffectScale][1.00]>
        >
        <[aerowing][RightWingAero][]
            <[string8][Body][RightWing]>
            <[string8][Flap0Control][ServoRightAileron.Output]>
            <[string8][Flap1Control][ServoFlaps.Output]>
            <[float64array][StationY]           [ -5.992 -3.595 -1.798 0.000 ]>
            <[float64array][StationLE]          [ 0.405 0.425 0.440 0.455 ]>
            <[float64array][StationTE]          [ -0.895 -0.955 -1.000 -1.045 ]>
            <[float64array][StationZ]           [ 0.224 0.098 0 0.004 -0.090 ]>
    <[float64array][StationIncidence]   [ 0.0698 0.0698 0.0698 0.0698 ]>
            <[uint32array][StationFlap]         [ 1 2 0 0 ]>
            <[float64array][StationFlapFraction][ 0.30 0.30 0.00 0.00 ]>
            <[float64][AspectRatioMultiplier][2.0]>
            <[string8][AirfoilRoot][AirfoilRoot]>
            <[string8][AirfoilTip][AirfoilTip]>
            <[float64][Flap0Area][0.300]>
            <[float64][Flap1Area][0.300]>
            <[string8][DownWashInput][RightWingAero.DownWashMean]>
            <[float64][DownWashPercentage][1.00]>
            <[float64][GroundEffectFactor][1.00]>
            <[float64][GroundEffectScale][1.00]>
        >

optica.zip

[jayeye2011]

This optica.tmd has flap area removed and span and area removed. However because the fuselage Cdx is unrealistically low (0.075) the aircraft will behave like a glider at 0% throttle and full flaps at 50 degrees. I would imagine this needs to be increased to at least Cdx = 0.25 since the default C172 has Cdx = 0.21 and the Optica has that helicopter canopy front end which has to induce more drag than the C172. optica_tmd_no_flaparea_no_area_span.zip Here is a screenshot of full flaps 50deg at 0% throttle with Cdx = 0.75 floats like a glider

[jayeye2011]

Adjusted Fuselage Cdx to 2.0, ClFlap to 2.0, CdFlap to 0.3 CmFlap to -0.275 However, excessive engine-propeller induced left roll effect needs some refinement as it requires to much right aileron roll to counter. I know it is engine-propeller related because it completely goes away when throttle is set to 0% (idle). It needs to be reduced although not necessarily eliminated completely otherwise people will just zero it out anyway using aileron trim which is not present in the real aircraft because of how annoying it is in a flight simulator.

optica_tmd_CdxClFlapCdFlapCmFlap_adjusted.zip

[jayeye2011]

Adjusted propeller pitch to 1.7 from 1.52 so that engine rpm at 100% throttle seems more in line with max 2700 rpm. Normally on takeoff you should not even be able to get to max rpm so using pitch of 1.7 you get about 2600 rpm during takeoff and can cruise at 2200 rpm @79 kias optica_tmd_propellerpitch_adjusted.zip

Takeoff 100% throttle

Cruise

[jayeye2011]

I believe that with this last tmd file adjustment, I have done as much as I can for the FS4 optica. I still don't like it's lack of roll stability and wish it had more dihedral. I find it hard to keep on a constant heading since it requires a continuous bit of rudder and aileron roll adjustment, but I guess that is what the purists would want anyway. I also feel like the rudder is somewhat insensitive , but I don't know how the weird tail setup actually works to mix elevator and rudder inputs since, while there is a dedicated horizontal stabilizer there is also that weird twin inboard canted non-vertical vertical stabilizers which don't give you pure yaw only control. How are these to even mixed together since it seem to me that the canted fins induce both yaw and pitch moments when deflected.

[jayeye2011]

Actually, I was a bit premature in my last comment. Looking at the Left and Right Vertical stabilizer definitions, they don't make a lot of sense to me. The Optical has twin vertical stabilizers, each mounted on twin booms that are offset from the aircraft's longitudinal centerline and each fin is canted inward like this / \ which is sorta reverse of say an F/A-18 twin vertical stabilizers. However they should have duplicate X-coordinates (StationLE and StationTE). And they should have the same Z-coordinates. The Y-coordinate position should be symmetric opposites. Also the StationFlap Fraction should have the same 0.35 value as currently the LeftVertStabilizerAero has 0.0 instead of 0.35 that RightVertStabilizerAero has defined. The current settings do not seem to conform to this. <[aerowing][LeftVertStabilizerAero][] <[string8][Body][Fuselage]> <[string8][Flap0Control][ServoRudder.Output]> <[float64array][StationY] [ 1.277 1.366 1.720 ]> <[float64array][StationLE] [ -3.811 -3.756 -3.540 ]> <[float64array][StationTE] [ -4.881 -4.932 -5.140 ]> <[float64array][StationZ] [ 1.363 1.091 0.000 ]> <[float64array][StationIncidence] [ 0.000 0.000 0.000 ]> <[uint32array][StationFlap] [ 0 1 0 ]> <[float64array][StationFlapFraction][ 0.00 0.00 0.00 ]> <[float64][AspectRatioMultiplier][1.0]> <[string8][AirfoilRoot][AirfoilVerticalStabilizer]> <[string8][AirfoilTip][AirfoilVerticalStabilizer]> <[string8][PropwashInput][EnginePropeller.GetWash]> <[float64][PropwashPercentage][0.01]> <[float64][PropwashRotation][0.01]> <[float64][PropwashOmega][4.00]> <[string8][DownWashInput][LeftVertStabilizerAero.DownWashMean]> <[float64][DownWashPercentage][1.00]> <[float64][GroundEffectFactor][1.00]> <[float64][GroundEffectScale][1.00]> <[float64][BetaSlope] [8.0]> <[float64][BetaMax] [1.5]>

<[aerowing][RightVertStabilizerAero][] <[string8][Body][Fuselage]> <[string8][Flap0Control][ServoRudder.Output]> <[float64array][StationY] [ -1.673 -1.319 -1.230 ]> <[float64array][StationLE] [ -3.542 -3.758 -3.812 ]> <[float64array][StationTE] [ -5.142 -4.934 -4.882 ]> <[float64array][StationZ] [ 0.057 1.147 1.420 ]> <[float64array][StationIncidence] [ 0.000 0.000 0.000 ]> <[uint32array][StationFlap] [ 1 0 0 ]> <[float64array][StationFlapFraction][ 0.30 0.00 0.00 ]> <[float64][AspectRatioMultiplier][1.0]> <[string8][AirfoilRoot][AirfoilVerticalStabilizer]> <[string8][AirfoilTip][AirfoilVerticalStabilizer]> <[string8][PropwashInput][EnginePropeller.GetWash]> <[float64][PropwashPercentage][0.01]> <[float64][PropwashRotation][0.01]> <[float64][PropwashOmega][4.00]> <[string8][DownWashInput][RightVertStabilizerAero.DownWashMean]> <[float64][DownWashPercentage][1.00]> <[float64][GroundEffectFactor][1.00]> <[float64][GroundEffectScale][1.00]> <[float64][BetaSlope] [8.0]> <[float64][BetaMax] [1.5]>

Since the vertical stabilizers seem to be non-symmetric, this would result in unbalanced aerodynamic forces during flight that would cause issues with both roll axis imbalance and rudder response behaviors. This needs to be double checked and corrected if wrong. I don't know what the correct values would be here.

[jayeye2011]

This optima.tmd file fixes the left and right vertical stabilizer issue (https://github.com/krzysk1/optica/issues/6#issuecomment-1386347090 )and includes all the fixes from the prior comments in this issue thread. optica_tmd_all_flight_model_fixes.zip

[krzysk1]

Some remarks: I suggest to remove propwash from wings because propeller is behind wings and make no input on them

            <[string8][PropwashInput][EnginePropeller.GetWash]>
            <[float64][PropwashPercentage][0.01]>
            <[float64][PropwashRotation][0.01]>
            <[float64][PropwashOmega][4.00]>

Last value in StationFlap and StationFlapFraction is unimportant and can be zero: <[uint32array][StationFlap] [ 0 1 0 ]> <[float64array][StationFlapFraction][ 0.00 0.30 0.00 ]> (successive numbers indicate whole sections between 1 to 2, 2 to 3, 3 to 4, etc. point on the X axis. Last number doesn't indicate any section) first number in StationFlap was zero because the first section has no rudder surface, but it is small very section (about 20 cm hight) and make no impact.

The propeller angle <[tmvector3d][X0][0.9986 0.0 0.05234]> caused the propeller stream to be directed slightly downwards. The new setting [1 0 0] makes the propeller stream horizontal. I do not know how it is in reality

[jayeye2011]

Yeah, I just put the prop wash stuff in there for completeness only, the values are set very low so hopefully no real impact. I personally do not like to rely on assuming there is some default for parameters not specifically declared in the tmd file. Especially when there is absolutely no documentation that defines what the default settings would be in the first place. Also, I was using the IPACS F15e and F18 tmd files as template examples for the twin vertical stabilizer issue resolution. I will adjust my personal version of the optica.tmd file but obviously what to include in the optica main branch repository update is purely a matter for your decision alone. I hope you can take a look into reducing but not completely eliminating the propellor torque induced left roll behavior though. Edit: My custom version zip file already has the X0 unit vector correction in it.

[jayeye2011]

<[uint32array][StationFlap] [ 0 1 0 ]> No - I just tested this and the rudder is not effective at all. This is using the original right vertical stabilizer station dimensions as the basis for the left vertical stabilizer taken into account the vertical stabilizer specific aerowing format rule which is different from the normal wing and horizontal stabilizer mirroring rules (as seen in F18 and F15e tmd files). Here is what I am using now and it actually responds correctly and with authority to left and right rudder control inputs. Not sure about the BetaSlope and BetaMax values since there is no interface definition for these, but it's in the FS 4 Aircraft SDK DR400 tmd file (and changing the values does not seem to do anything, so no harm in including it in case it becomes relevant later on). <[aerowing][LeftVertStabilizerAero][] <[string8][Body][Fuselage]> <[string8][Flap0Control][ServoRudder.Output]> <[float64array][StationY] [ 1.673 1.319 1.230 ]> <[float64array][StationLE] [ -3.542 -3.758 -3.812 ]> <[float64array][StationTE] [ -5.142 -4.934 -4.882 ]> <[float64array][StationZ] [ 0.057 1.147 1.420 ]> <[float64array][StationIncidence] [ 0.000 0.000 0.000 ]> <[uint32array][StationFlap] [ 1 1 0 ]> <[float64array][StationFlapFraction][ 0.30 0.30 0.30 ]> <[float64][AspectRatioMultiplier][1.0]> <[string8][AirfoilRoot][AirfoilVerticalStabilizer]> <[string8][AirfoilTip][AirfoilVerticalStabilizer]> <[string8][PropwashInput][EnginePropeller.GetWash]> <[float64][PropwashPercentage][0.001]> <[float64][PropwashRotation][0.001]> <[float64][PropwashOmega][4.00]> <[string8][DownWashInput][LeftVertStabilizerAero.DownWashMean]> <[float64][DownWashPercentage][1.00]> <[float64][GroundEffectFactor][1.00]> <[float64][GroundEffectScale][1.00]> <[float64][BetaSlope] [8.0]> <[float64][BetaMax] [1.5]>

<[aerowing][RightVertStabilizerAero][] <[string8][Body][Fuselage]> <[string8][Flap0Control][ServoRudder.Output]> <[float64array][StationY] [ -1.673 -1.319 -1.230 ]> <[float64array][StationLE] [ -3.542 -3.758 -3.812 ]> <[float64array][StationTE] [ -5.142 -4.934 -4.882 ]> <[float64array][StationZ] [ 0.057 1.147 1.420 ]> <[float64array][StationIncidence] [ 0.000 0.000 0.000 ]> <[uint32array][StationFlap] [ 1 1 0 ]> <[float64array][StationFlapFraction][ 0.30 0.30 0.30 ]> <[float64][AspectRatioMultiplier][1.0]> <[string8][AirfoilRoot][AirfoilVerticalStabilizer]> <[string8][AirfoilTip][AirfoilVerticalStabilizer]> <[string8][PropwashInput][EnginePropeller.GetWash]> <[float64][PropwashPercentage][0.001]> <[float64][PropwashRotation][0.001]> <[float64][PropwashOmega][4.00]> <[string8][DownWashInput][RightVertStabilizerAero.DownWashMean]> <[float64][DownWashPercentage][1.00]> <[float64][GroundEffectFactor][1.00]> <[float64][GroundEffectScale][1.00]> <[float64][BetaSlope] [8.0]> <[float64][BetaMax] [1.5]>

Here is the revised optica.tmd file optica_tmd_20230118_effective_rudder.zip

You are free to use it or not.

[jayeye2011]

An alternative is to use the original left vertical stabilizer aerowing station dimensions instead of the right vertical stabilizer ones (I do not know which are correct but they are not the same), put into the correct order for FS4 vertical stabilizer format as follows: <[aerowing][LeftVertStabilizerAero][] <[string8][Body][Fuselage]> <[string8][Flap0Control][ServoRudder.Output]> <[float64array][StationY] [ 1.720 1.366 1.277 ]> <[float64array][StationLE] [ -3.540 -3.756 -3.811 ]> <[float64array][StationTE] [ -5.140 -4.932 -4.881 ]> <[float64array][StationZ] [ 0.000 1.091 1.363 ]> <[float64array][StationIncidence] [ 0.000 0.000 0.000 ]> <[uint32array][StationFlap] [ 1 1 0 ]> <[float64array][StationFlapFraction][ 0.30 0.30 0.30 ]> <[float64][AspectRatioMultiplier][1.0]> <[string8][AirfoilRoot][AirfoilVerticalStabilizer]> <[string8][AirfoilTip][AirfoilVerticalStabilizer]> <[string8][PropwashInput][EnginePropeller.GetWash]> <[float64][PropwashPercentage][0.001]> <[float64][PropwashRotation][0.001]> <[float64][PropwashOmega][4.00]> <[string8][DownWashInput][LeftVertStabilizerAero.DownWashMean]> <[float64][DownWashPercentage][1.00]> <[float64][GroundEffectFactor][1.00]> <[float64][GroundEffectScale][1.00]> <[float64][BetaSlope] [8.0]> <[float64][BetaMax] [1.5]>

<[aerowing][RightVertStabilizerAero][] <[string8][Body][Fuselage]> <[string8][Flap0Control][ServoRudder.Output]> <[float64array][StationY] [ -1.720 -1.366 -1.277 ]> <[float64array][StationLE] [ -3.540 -3.756 -3.811 ]> <[float64array][StationTE] [ -5.140 -4.932 -4.881 ]> <[float64array][StationZ] [ 0.000 1.091 1.363 ]> <[float64array][StationIncidence] [ 0.000 0.000 0.000 ]> <[uint32array][StationFlap] [ 1 1 0 ]> <[float64array][StationFlapFraction][ 0.30 0.30 0.30 ]> <[float64][AspectRatioMultiplier][1.0]> <[string8][AirfoilRoot][AirfoilVerticalStabilizer]> <[string8][AirfoilTip][AirfoilVerticalStabilizer]> <[string8][PropwashInput][EnginePropeller.GetWash]> <[float64][PropwashPercentage][0.001]> <[float64][PropwashRotation][0.001]> <[float64][PropwashOmega][4.00]> <[string8][DownWashInput][RightVertStabilizerAero.DownWashMean]> <[float64][DownWashPercentage][1.00]> <[float64][GroundEffectFactor][1.00]> <[float64][GroundEffectScale][1.00]> <[float64][BetaSlope] [8.0]> <[float64][BetaMax] [1.5]>

Here is the tmd file using the left vertical stabilizer (corrected format) as the basis for the right vert stab.

optica_tmd_20230118_effective_rudder_leftstab_basisi.zip

[jayeye2011]

~I feel like the alterations presented in this issue thread covered more than just the nose heavy problem and basically all the most significant issues related to the aerodynamic portions of the Optica model. If these or reasonably similar changes are incorporated into the main branch then I think with exception of a fully functional 6-pack instrument, communications, navigation panel and operable cockpit controls, the FS4 version of the Optica will be in decent shape for public use. Some may take issue with it not performing exactly to specification but they are free to further tweak it themselves.~ NEVER MIND - My configuration is not very realistic after all. There is no stall speed where you lose lift and the nose drops. Not sure what the deal is here. It's probably best if you come up with your own concept for the flight model as I am more or less a newbie guy anyway. I do think the airfoil CL0, CD0 and CM0 coming from airfoiltools.com for the airfoil is reasonable but I have no idea what the other FS2/4 airfoil parameters should be. I think the vertical stabilizers correction based on how the F18 and F15E tmd files spec them is correct because it does something when you apply rudder input where the original optica.tmd did not.

[jayeye2011]

I found some additional information by Jet-Pack(IPACS) on the Aerofly forum regarding the tmd.airfoil parameters. Still not sure I understand it all though. Figure it also applies to FS 2/4 https://www.aerofly.com/community/forum/index.php?thread/7264-how-to-create-an-airfoil-mh-30/ [How to create an Airfoil (MH 30) - aerofly RC 7 - IPACS Aerofly Forum.pdf] (https://github.com/krzysk1/optica/files/10455931/How.to.create.an.Airfoil.MH.30..-.aerofly.RC.7.-.IPACS.Aerofly.Forum.pdf) Obviously both the Optica and Wilga tmd:airfoil parameters ClAlpha, CdAlpha, CmAlpha, AttachedCenter, AttachedRange, and StallRange all need to be updated for their respective airfoiltools.com airfoil data using the method shown in Jet-Packs instructions. The AirfoilTools.com polar plots for LA(1)-0417 Reynolds # 1M Ncrit 9 is here http://airfoiltools.com/polar/details?polar=xf-ls417-il-1000000

[jayeye2011]

Here is the latest optica.tmd file that incorporates the proposed fixes that I have made. This is tuned using 4.75 deg wing incidence angle so that 74 knot cruise speed at 5000 ft using 2100rpm (41% throttle) 0 deg elevator trim. Aileron right trim used to stabilize control inputs so as to get to steady state cruise. Includes 30 deg nose wheel steering and effect rudder fixes.

20230216 4.75deg optica.zip

[jayeye2011]

Backing of the wing incidence angle from 4.75 deg down to 3.60 deg raised the cruise speed to 85 knots. revised optica with deprecated CrashOnContact and Blade parameter removed from tmd file. ji20230616c optica 3.60deg crashoncontact_blade_removed.zip