E190/170 aerodynamic tweak(for V2 only)

[C2615]

I made some tweaks for feelthere E-jets E190 mainly in aircraft.cfg and emb190.air to get better aerodynamic performence math to the realword data.

These tweak I originally mad for FS9 version, but after I move to P3dv4 just last year, I found it's still  needed and works.

The realword data source is E190 Airplane Opreation Manual I found online, you may try to search it, but I won't provide.

AOM is for opreational and NOT for aerodynamic or performance engineering, just keep that in mind.

 

Rather than simply put were you need to modify, I'd rather share some backgorund information, so any other people intersted in, or hopefully devs working on new 64bit version, could get something useful.

And if you try to implant my tweaks, just remember back up your files!

 

So first time I got the AOM, I immediately try it's Simplified flight planning charts to make fuel and time cauculation for my sim flight, it turns out the fuel used is way off the caculation, that starts my journey for aero editing,  to get the perrformence I needed.

The goal is: a reasonable fuel predection,  so a nice match in cruise is 1st priority, then the Climb and Decent better to math tables too, for the take-off and landing part, I just wanna make sure with proper Vspeed, the aircraft could climb with single engine if needed, and not ruin it when things changed with cruise preformence., and for cruise under FL250 which i typically won't do, and Hold at low level and any other flight phase inside or outside the envelope, I simply didn't try to work on it.

 

First thing I noticed is, the curise performence is way off the ALL ENGINES OPERATING CRUISE TABLE in AOM, so I just set the weight, the FL, use AP/AT to see,the behaivor, and adjust the cruise_lift_scalar and engine thrust curves to match the N1 needed to keep level flight at given speed

The only part I touched with emb190.air is the  1506 table, Thrust vs N1 and Mach No, I can'y copy it into text, so here is the table:

 

M,      0,     20,      25,      30,      35,      40,      45,      50,      55,      60,      65,      70,      75,      80,      85,      90,      95,      100,    105
0.0, 0.00,  0.11,   0.15,    0.18,   0.20,   0.24,  0.28,    0.30,   0.39,   0.46,   0.54,   0.59,   0.64,   0.72,   0.89,   1.00,    1.11,    1.15,    1.17
0.2, 0.00,  0.05,   0.07,    0.10,   0.14,   0.17,  0.23,    0.30,   0.39,   0.46,   0.54,   0.59,   0.64,   0.73,   0.89,   1.00,    1.11,    1.15,    1.17
0.4, 0.00,	0.07,   0.10,    0.14,   0.18,   0.21,   0.26,   0.30,   0.39,   0.46,   0.54,   0.59,   0.64,   0.73,   0.89,   1.00,    1.11,    1.15,    1.17
0.6, 0.00,	0.11,   0.16,    0.20,   0.25,   0.30,   0.35,   0.39,   0.45,   0.51,   0.58,   0.61,   0.65,   0.68,   0.92,   1.08,    1.23,    1.23,    1.25
0.7 ,0.00,	0.20,   0.23,    0.27,   0.32,   0.36,   0.41,   0.44,   0.51,   0.59,   0.65,   0.71,   0.75,   0.79,   0.97,   1.18,    1.35,    1.36,    1.38
0.9 ,0.00,	0.23,   0.27,    0.31,   0.36,   0.40,   0.46,   0.50,   0.59,   0.68,   0.75,   0.83,   0.90,   0.94,   1.10,   1.29,    1.37,    1.40,    1.45

Ah, I just can't keep it in line... go figure...

I edit it with AirEd, you can find it free online, and there are other tools.

for Aircraft.cfg:

[flight_tuning]
cruise_lift_scalar=1.260

[jet_engine]
thrust_scalar=0.83

Now, that makes N1 match within 7~10% at a normal cruise, I'm ok with this.

But the goal is fuel flow, after more test flight, I get this.

[GeneralEngineData]
fuel_flow_scalar=1.35

[TurbineEngineData]
fuel_flow_gain=0.0012

Now the fuel flow for most cruising condition is in 5% error,  i feel good with that.

Notice, these are final results I got, so you can just use it, But I also did flight test with Takeoff Landing, and climb/des and do more tweaks to make sure it doesn't ruin these condtion. the low mach region in 1506 table is manily for that.

The climb and decend data I just try to match the time show on AOM table, since speed is keeped by AP/AT and thus distance, The error now is  less than 2 minutes from sea level all the way up to FL350, But it nolonger match the FMC VNAV prediction in feelthere.

Another problem I had is the Trim goes wild when apparoching, so I get some tweak here too, to make it more reasonable, Now the trim for approach is like 4~5 unit.:

[flight_tuning]
elevator_trim_effectiveness=3.500

[airplane_geometry]
htail_incidence=-18

side effect is, The AOA are rather low at high speed decent, while OK when cruising.

Also, according to AOM, the take off trim should be near 1 for a 25% CG, but in feelthere avionics the green band is near 3, so the trim for this tweak is still somewhere near 3, for not to set off the alarm, the AOM table not works here.

To fix the approach performence, I needed to add some lift for flaps:

[flaps.0]

lift_scalar=1.20

The "green dot" on speed tape just not work well, The flaps manuver speed in AOM shows:

UP   210
1      180
2      160
3      150
4      140
5      140
6      130

For take off with Flaps 2, you retract to 1 above retcation alt, and speed above 160, then after speed hit 180, retract up. the green dot just way too high

For approach, Flaps1 when 210, slow to 180, Flaps2 when hit 180 and slow to 160... you get the idea....

That's all modifcation I made is only for E190, I've tried to fit it in E170 as it is, but it doen't  work, I had the E170 AOM in imperial units, I had a check but just to see it doen't match well, and don't want spend more time on it. E175 and 195, I don't even have the data.

 

FOR E170: 1506 table same as E190

[jet_engine]
thrust_scalar=0.780

[GeneralEngineData]
fuel_flow_scalar=1.18000

[TurbineEngineData]
fuel_flow_gain=0.0012

[flight_tuning]
cruise_lift_scalar=1.26
elevator_trim_effectiveness=2.000

don't change others E170 is better on trim and LRC by FMC
 

Know issue that I can't change. Hopefully get corrected with New 64bit version:

TO trim not match AOM, but works great by just set it in 3~4 units.(it works great on 170)

After take off, don't follow FD for climb, just pitch up to get speed V2+10~20 will be fine.

Greendot on speed tape for flaps not match, I just use the AOM data and it better fit the performence, even without these editing.

For P3Dv4 version, CLB2 is neede, somehow the N1 I get is higher than what AT set, and with CLB1, it could corss N1 redline, however not seen in FS9 version (It's OK for 170)

FMC VNAV climb just not fit.

FMC LRC speed way too slow, if you calculate fuel with LRC chart, manully adjust the mach number to where LRC table shows, around 0.72~0.78ish according to weight and Flight Level. rather than 0.65ish in feelthere FMC. or simply go M0.78 cruise. (LRC works great on E170)

Surprisingly, FMC fuel predection is OK.

VNAV decent could be use, with Enging not idel but 40+ N1.

VNAV won't handle At or Above type of ALT restriction, it only goes "At" it could trigger way too earlier TOD in some STARs.

When descending,  AOA looks very low or even minus.

Autopilot not follow  glide slope very well,  manual fly it will be OK.

 

Hope you enjoy these tweaks.  At least for me,  the E190 is now flyable for some nice route at day light, Thanks feelthere to provde a decent  avionics and normal system opreation to start with.

The new V3 170.190 is also off figure by now, but hope Feelthere will get it better!

[C2615]

Just did some quick test with the V3 version.

LRC FL300, very typical condition.

For E190, with 10200LB, the FMC gives me LRC for M.66, but AOM gives me M.72

manual Speed to M.72 the aircraft gose FF:1640PPH and N1 on 75.7

on AOM, for 50000kg weight, the FF should be 1056Kph(2330pph) N1 should be 83.5

 

For E170, with 82000LB, FMC LRC is M.68,AOM M.67, so that's OK

But, with M.68, FF GIVES 1200PPH. while manual gives 1756PPH under same condition.

and N1 as low as 77.2 rather than 83.2 on the AOM.

 

So....aerodynamic side, V3 is as "good" as the old one.... that makes my fuel plan from AOM's SFP chart useless,  always overweight on landing....

 I'll see if my original tweaks will works with the new one then....

[raam123]

2 hours ago, C2615 said:

Just did some quick test with the V3 version.

LRC FL300, very typical condition.

For E190, with 10200LB, the FMC gives me LRC for M.66, but AOM gives me M.72

manual Speed to M.72 the aircraft gose FF:1640PPH and N1 on 75.7

on AOM, for 50000kg weight, the FF should be 1056Kph(2330pph) N1 should be 83.5

 

For E170, with 82000LB, FMC LRC is M.68,AOM M.67, so that's OK

But, with M.68, FF GIVES 1200PPH. while manual gives 1756PPH under same condition.

and N1 as low as 77.2 rather than 83.2 on the AOM.

 

So....aerodynamic side, V3 is as "good" as the old one.... that makes my fuel plan from AOM's SFP chart useless,  always overweight on landing....

 I'll see if my original tweaks will works with the new one then....

Sorry to read that 😞

Please let the community know how it goes and thx for effort !

[C2615]

Just edited it for:

• Make clear it's for V2 only, not V3
• Texted 1506 table
• Added E170

[Sabretooth78]

I applied these "fixes" to the V2 E190 and it definitely brings the fuel consumption much more in line with SimBrief predictions and it's nice to now be able to land flaps 5 and still be able to see the runway!

One additional change I applied was the following:

[brakes]
toe_brakes_scale=0.80

Default brakes are 0.50 and they feel, at least to me, to be very weak especially when compared to the braking action of other higher quality add-on aircraft.  For instance, if you even slightly float a landing at KDCA and/or don't punch full reverse immediately, you're most likely going to buy the Potomac.  A number somewhere between 0.75 and 0.85 seems to bring it a little closer in line with the others.  Of course, as a disclaimer, I don't have experience with the real thing, so your mileage may vary.