LO's F-15 vs. the F-15 Streak Eagle

[britgliderpilot]

What data did you feed this Sim? AIr flow, fuel flow to burner and afterburner, bypass ratio, pressure coefficients for compressors and turbines, efficiency numbers, etc?

 

I fed it the default data that NASA supply as part of the F100 engine description.

 

When I went back to check the numbers, it seems NASA are actually modelling the engine as a turgojet rather than a turbofan - it's not using any bypass ratio at all.

 

The real thing has a small bypass ratio (0.36:1 according to Wiki), so it's not a BAD approximation, but there's an error right there :P

 

 

Anyways - current NASA model.

 

Compressor:

 

14 stages

Pressure ratio 20.4:1

Efficiency 0.959

 

 

Burner:

 

No pressure losses.

Efficiency 0.984

 

 

Turbine:

 

4 stages

Efficiency 0.982

 

 

It's eating 17748 kg of Jet A an hour, at 99.164 kg/s airflow.

 

 

Will try and duplicate it in the Turbofan model and see what it says this time around - I think the software's limited to using movable inlets on turbojets, but since we're running at sea level and no forward speed it shouldn't matter.

[D-Scythe]

So, to conclude on my part, surely LockOn is not maching this record especially in exit speed but hey, it's not supposed to as let me remind you again, this is a RECORD achieved once with airframe set up specifically for this.

 

Again, the airframe was NOT set up "specifically" for this record. Basically, stuff was taken out - it's STILL an F-15.

 

And yes, this is a record - but you don't miss your "record" 14 000 ft in 56 seconds. The difference is just too significant to ignore.

 

Oh and... I just remembered someone said the engines for the test airframe had modified engines (boosted) so I'm not surprised it achieved much higher exit speed. I wouldn't be surprised if that was fitted especially for better engine performance and higher thrust at higher altitudes.

 

Again, we've been over this.

[D-Scythe]

I can not too.... and I have very strong feeling that nobody can. :). SwingKid if I was told yesterday prooved that F-15 CAn NOT accelerate vertically.

The main reason is that it can not position itself at the altitude where its thrust is more than weight at 90 deg pitch. Sic.

 

But the point is that real pilots have accelerated their real F-15s in the vertical.

[britgliderpilot]

Righty - EngineSim's too limited for this estimation.

 

It can't deal with afterburning turbofans, which is probably why they were using the turbojet approximation.

 

As such . . . . you just can't get a decent answer out of it. It'd be possible to work it out theoretically with Excel, but you'd still be relying on guesses in certain places.

 

 

The furthest I've got is by using the non-afterburning turbofan approximation with:

 

0.36:1 bypass

1.745 fan pressure ratio (guessed, it was a default ES figure)

10 stage compressor with pressure ratio of 14 (brings overall PR to 25)

Fan diameter of 0.88m (from web reference stating inlet dia as 34.8 inches)

 

Which throws out 16,000lbs dry thrust, about 1,500lb more than the stated dry thrust of the F-100.

 

 

All of which tells us . . . . . actually very little :P

 

Up the speed to 300mph and you lose 2,000lb of thrust, which at least should prove you can't climb vertically in an F-15 without burner. Which was never questioned. Bugger.

[GGTharos]

Is it just me, or is there supposed to be an increase in thrust as you speed up due to ram-air effects?

[D-Scythe]

Is it just me, or is there supposed to be an increase in thrust as you speed up due to ram-air effects?

 

That's what I thought too.

[TucksonSonny]

Originally Posted by D-Scythe

Is this guy serious? Is he making up numbers? Please tell me this is just a joke and he's making up numbers.

 

Perfectly normal for him.

 

COPY-PASTE from Wikipedia and Falcon Tactical reference!

 

Which part did you NOT read/understand? :mad:

 

This time it is not a joke!

[SwingKid]

F = m * a

 

If anyone wants to know how much thrust Lock On's F-15 is really producing, simply measure its acceleration on the runway, and divide by its weight.

 

Good luck..

 

-SK

[Yo-Yo]

Anyways - current NASA model.

Compressor:

14 stages

Pressure ratio 20.4:1

Efficiency 0.959

Burner:

No pressure losses.

Efficiency 0.984

Turbine:

4 stages

Efficiency 0.982

.

Is it efficiency per a stage or overall?

 

But if it were efficiency per a stage they seem very optimistic. For example,

0.86-0.92 is typical for modern engines as well as .93 for turbine.

 

One percent in compressor efficiency is not 1% in engine performance...

 

By the way, everywhere inclding PW site I've found that PR is 32-35 for F100.

[britgliderpilot]

Is it efficiency per a stage or overall?

 

But if it were efficiency per a stage they seem very optimistic. For example,

0.86-0.92 is typical for modern engines as well as .93 for turbine.

 

Yup - I had some sample efficiencies somewhere for a Uni design project that I used for the turbojet numbers, which as we've seen agrees a little bit better with the real number.

 

Still not sure whether it's per stage or overall, though - it's not stated in the interface and I'm not sure how to get into the workings of the applet.

 

 

Is it just me, or is there supposed to be an increase in thrust as you speed up due to ram-air effects?

 

There is - it's just that when going from zero forward speed to a "low" airspeed it's offset by the increased inlet drag.

 

Running the same thing again with the turbojet with variable inlet, EngineSim says the initial drop in net thrust is much less than with the turbofan.

 

Am a bit rusty on this, but I think I've got it right.

[britgliderpilot]

By the way, everywhere inclding PW site I've found that PR is 32-35 for F100.

 

Yep, mine said that as well.

 

However . . . . if you look in a bit more detail, it says that that's the case for the -229 with F119 R&D going into it, while the original versions still had the 25:1 OPR.

 

I'd be shocked if the F100 had a 35:1 OPR at entry into service in the 70's.

[S77th-GOYA]

Ok, I said that Engine Sim was modelling a higher output F100. Probably the -229.

 

So what thrust does the LOMAC F100 produce at 3400 feet and 219 knots? It is obviously lower than 18,210 lbs per engine.

 

And what is LOMAC's modeling based upon?

[britgliderpilot]

Ok, I said that Engine Sim was modelling a higher output F100. Probably the -229.

 

So what thrust does the LOMAC F100 produce at 3400 feet and 219 knots? It is obviously lower than 18,210 lbs per engine.

 

And what is LOMAC's modeling based upon?

 

EngineSim's model is for a turbojet rather than a turbofan, and while the efficiencies are greater than you'd expect, the material limits are rather lower than you'd expect. As such . . . . I don't know quite what they've done.

 

I wouldn't class it as a workable estimation for any F100, to be honest.

[Yo-Yo]

Ok, I said that Engine Sim was modelling a higher output F100. Probably the -229.

 

So what thrust does the LOMAC F100 produce at 3400 feet and 219 knots? It is obviously lower than 18,210 lbs per engine.

 

And what is LOMAC's modeling based upon?

 

Yes it's lower.

Frankly, there is no modelling of an engine in Lomac. In Lomac but not in BS. In Lomac engine thrust is stored as a table vs M and ambient conditions.

 

The problem is how many degrees of freedom we have tuning the performance. If we have exact aerodynamics and performance we even don't need to have engine thrust - it can be tuned even w/o iterations. The same is for the case when we have engine thrust and performance. But the most interesting case is when we have only performance and thrust at one Mac number point. The common procedure is to estimate aerodynamics using some performance data coupling with the aerodynamic estimation using airframe dimensions, reports data, etc. Then the typical thrust curves is implemented (there are some little secrets how to estimate the forms of the curves :) and some points of it).

Then a several passes of iteration (by the hands exclusively) are performed tailoring both aero and thrust... the main feature of plane dynamics is that it is self-crosslinked... if you have wrong combination of aero and thrust it can fit only one point of the several you need to fit. If you have a suitable tool it is not hard to fit all the points.

 

The hardest case is when we have neither performance nor thrust/aero data... :)

[S77th-GOYA]

Yes it's lower.

Frankly, there is no modelling of an engine in Lomac. In Lomac but not in BS. In Lomac engine thrust is stored as a table vs M and ambient conditions.

 

The problem is how many degrees of freedom we have tuning the performance. If we have exact aerodynamics and performance we even don't need to have engine thrust - it can be tuned even w/o iterations. The same is for the case when we have engine thrust and performance. But the most interesting case is when we have only performance and thrust at one Mac number point. The common procedure is to estimate aerodynamics using some performance data coupling with the aerodynamic estimation using airframe dimensions, reports data, etc. Then the typical thrust curves is implemented (there are some little secrets how to estimate the forms of the curves :) and some points of it).

Then a several passes of iteration (by the hands exclusively) are performed tailoring both aero and thrust... the main feature of plane dynamics is that it is self-crosslinked... if you have wrong combination of aero and thrust it can fit only one point of the several you need to fit. If you have a suitable tool it is not hard to fit all the points.

 

The hardest case is when we have neither performance nor thrust/aero data... :)

 

Well that shut everybody up. :smilewink:

[TucksonSonny]

If we have exact aerodynamics and performance we even don't need to have engine thrust - it can be tuned even w/o iterations. :)

 

Something like this?

 

#Title:F15C 220

 

# BASIC AERODYNAMIC COEFFICIENTS

#

#

# MACH BREAKPOINTS

#

14 # Num MACH

0 0.2 0.4 0.6

0.8 0.97 1 1.2 1.4

1.6 1.8 2 2.2 2.5

#

# ALPHA BREAKPOINTS

#

12 # Num Alpha

-20 -10 -5 0

5 10 15 20 25

30 35 40

#

# LIFT COEFFICIENT CL

#

1 # Table Multiplier

#

# Mach 0.00

-0.8143 -0.5923 -0.2062 0.05 0.365 0.64

0.91 1.148 1.225 1.3781 1.4615 1.4518

#

# Mach 0.20

-0.8143 -0.5923 -0.2062 0.05 0.365 0.64

0.91 1.1148 1.225 1.3781 1.4615 1.4518

#

# Mach 0.40

-0.8143 -0.5923 -0.2062 0.05 0.365 0.64

0.91 1.106 1.2222 1.285 1.3684 1.3587

#

# Mach 0.60

-0.859 -0.634 -0.2446 0.02 0.335 0.635

0.86 1 1.15 1.23 1.3333 1.3294

#

# Mach 0.80

-0.874 -0.649 -0.2596 0.005 0.35 0.65

0.84 0.965 1.65 1.9069 2.0102 2.0063

#

# Mach 0.97

-0.9022 -0.6334 -0.2566 0.003 0.43 0.74

0.93 1.2045 1.3765 1.635 1.7339 1.7439

#

# Mach 1.00

-0.9022 -0.6334 -0.2566 0.003 0.43 0.74

0.93 1.2045 1.3765 1.635 1.7339 1.7439

#

# Mach 1.20

-0.8824 -0.6285 -0.2413 0.003 0.32 0.6

0.85 1.0789 1.2233 1.4841 1.5824 1.5953

#

# Mach 1.40

-0.8704 -0.6165 -0.2293 0.042 0.27 0.52

0.75 0.995 1.1415 1.4023 1.5006 1.5135

#

# Mach 1.60

-0.8524 -0.5985 -0.2113 0.06 0.25 0.45

0.65 0.9321 1.0765 1.3373 1.4356 1.4485

#

# Mach 1.80

-0.8624 -0.6085 -0.2213 0.05 0.25 0.425

0.6298 0.9119 1.0563 1.3171 1.4154 1.4283

#

# Mach 2.00

-0.8267 -0.5477 -0.1704 0.05 0.235 0.398

0.6951 0.9653 1.1454 1.4058 1.4855 1.4953

#

# Mach 2.20

-0.8417 -0.5627 -0.1854 0.035 0.21 0.36

0.7068 0.977 1.1571 1.4175 1.4972 1.507

#

# Mach 2.50

-0.8767 -0.5977 -0.2204 0 0.14 0.3

0.6836 0.9538 1.1339 1.3943 1.474 1.4838

#

# DRAG COEFFICIENT CD

#

0.66666 # Table Multiplier

#

# Mach 0.00

0.2262 0.1763 0.064 0.0215 0.0352 0.0944

0.2188 0.4459 0.5629 0.8475 1.0937 1.3476

#

# Mach 0.20

0.1852 0.1453 0.0554 0.0215 0.0352 0.0944

0.2188 0.3653 0.5379 0.7655 0.9626 1.1657

#

# Mach 0.40

0.1862 0.1463 0.0564 0.0215 0.0371 0.0932

0.2291 0.3319 0.5045 0.7321 0.9291 1.1322

#

# Mach 0.60

0.1995 0.1597 0.0655 0.0218 0.0338 0.0867

0.1768 0.255 0.4261 0.6553 0.8449 1.0565

#

# Mach 0.80

0.2022 0.1624 0.0682 0.0219 0.034 0.0987

0.182 0.2247 0.344 0.5733 0.7629 0.9745

#

# Mach 0.97

0.2215 0.1526 0.0822 0.0284 0.0628 0.168

0.23 0.3883 0.561 0.7875 1.048 1.1833

#

# Mach 1.00

0.2255 0.1566 0.0862 0.0324 0.0706 0.1658

0.2314 0.375 0.5478 0.7743 1.0348 1.1701

#

# Mach 1.20

0.2848 0.1835 0.1147 0.0488 0.0708 0.158

0.253 0.3424 0.5145 0.7464 1.1073 1.2327

#

# Mach 1.40

0.2846 0.1832 0.1145 0.0509 0.0653 0.147

0.2113 0.3629 0.535 0.7669 1.1278 1.2532

#

# Mach 1.60

0.2798 0.1784 0.1097 0.05 0.064 0.126

0.2066 0.3582 0.5303 0.7622 1.1231 1.2485

#

# Mach 1.80

0.2755 0.1741 0.1054 0.0465 0.066 0.1217

0.185 0.3365 0.5087 0.7405 1.1014 1.2269

#

# Mach 2.00

0.2704 0.1674 0.101 0.044 0.0664 0.1192

0.193 0.3526 0.5257 0.7556 0.9575 1.1039

#

# Mach 2.20

0.2745 0.1715 0.1051 0.043 0.0639 0.117

0.1666 0.3261 0.4992 0.7291 0.931 1.0774

#

# Mach 2.50

0.2865 0.1834 0.117 0.042 0.052 0.106

0.1455 0.305 0.4781 0.708 0.9099 1.0563

#

# SIDE FORCE DERIVATIVE CY-BETA

#

0.6 # Table Multiplier

#

# Mach 0.00

-0.011 -0.0109 -0.0166 -0.0182 -0.0192 -0.0187

-0.0163 -0.0176 -0.0164 -0.0158 -0.0141 -0.009

#

# Mach 0.20

-0.011 -0.0109 -0.0166 -0.0182 -0.0192 -0.0187

-0.0163 -0.0176 -0.0164 -0.0158 -0.0141 -0.009

#

# Mach 0.40

-0.011 -0.0109 -0.0166 -0.0182 -0.0192 -0.0187

-0.0163 -0.0176 -0.0164 -0.0158 -0.0141 -0.009

#

# Mach 0.60

-0.011 -0.0109 -0.0166 -0.0182 -0.0192 -0.0187

-0.0163 -0.0176 -0.0164 -0.0158 -0.0141 -0.009

#

# Mach 0.80

-0.012 -0.0118 -0.018 -0.0195 -0.0197 -0.02

-0.0174 -0.0182 -0.0171 -0.0168 -0.0155 -0.0142

#

# Mach 0.97

-0.016 -0.0122 -0.021 -0.028 -0.0286 -0.03

-0.025 -0.0267 -0.0223 -0.0215 -0.0187 -0.0172

#

# Mach 1.00

-0.016 -0.0122 -0.021 -0.028 -0.0286 -0.03

-0.025 -0.0267 -0.0223 -0.0215 -0.0187 -0.0172

#

# Mach 1.20

-0.017 -0.0172 -0.027 -0.033 -0.035 -0.0333

-0.0321 -0.0288 -0.0254 -0.0231 -0.0207 -0.0188

#

# Mach 1.40

-0.0172 -0.0173 -0.0272 -0.0335 -0.0355 -0.0338

-0.0326 -0.0292 -0.026 -0.024 -0.021 -0.02

#

# Mach 1.60

-0.0172 -0.0173 -0.0272 -0.0335 -0.0355 -0.0338

-0.0326 -0.0292 -0.026 -0.024 -0.021 -0.02

#

# Mach 1.80

-0.0172 -0.0173 -0.0272 -0.0335 -0.0355 -0.0338

-0.0326 -0.0292 -0.026 -0.024 -0.021 -0.02

#

# Mach 2.00

-0.0172 -0.0173 -0.0272 -0.0335 -0.0355 -0.0338

-0.0326 -0.0292 -0.026 -0.024 -0.021 -0.02

#

# Mach 2.20

-0.0172 -0.0173 -0.0272 -0.0335 -0.0355 -0.0338

-0.0326 -0.0292 -0.026 -0.024 -0.021 -0.02

#

# Mach 2.50

-0.0161 -0.0162 -0.0194 -0.0194 -0.0215 -0.0216

-0.0214 -0.0215 -0.0205 -0.0179 -0.0153 -0.0105

# End of Aero Data

#

#

# PROPULSION DATA

#

2 # Thrust multiplier

0.6 # Fuel Flow Multiplier

#

# MACH BREAKPOINTS

#

19 # Number of Mach Breaks

0 0.2 0.4 0.6 0.8 0.9

1 1.1 1.2 1.3 1.4 1.5 1.6

1.7 1.8 1.9 2 2.1 2.2

#

# ALTITUDE BREAKPOINTS

#

8 # Number of Alt Break Points

0 10000 20000 30000 40000 50000

60000 100000

#

# THRST1 - THRUST AT IDLE (THROTL = 0.00)

#

# Alt 0

800 635 60 -1020 -2700 -3850 -3600 300 5000 8700 9455 8873 8385 7971 7625 7342 7108 6944 6797

#

# Alt 10000

610 425 25 -710 -1900 -2125 -1400 1600 5000 7500 8018 7613 7230 6917 6630 6403 6213 6037 5913

#

# Alt 20000

790 690 345 -300 -1300 -1400 -595 2050 5000 6500 6867 6646 6517 6425 6316 6283 6270 6250 6224

#

# Alt 30000

1160 1010 755 350 -247 -650 -342 1700 4300 5500 6194 6268 6379 6438 6490 6528 6562 6650 6667

#

# Alt 40000

1460 1330 1130 910 600 -25 -200 1000 2900 4600 5600 6054 6544 7042 7475 7910 8282 8655 8972

#

# Alt 50000

1800 1700 1525 1360 1100 800 700 1500 2500 3500 4622 5130 5764 6266 6748 7208 7594 7940 8255

#

# Alt 60000

700 750 860 975 1150 1275 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800

#

# Alt 100000

56 53 48 43 34 25 22 47 81 117 143 159 166 168 169 169 169 168 164

#

# THRST2 - THRUST AT MIL POWER (THROTL = 1.00)

#

# Alt 0

12500 12330 12260 12290 12350 12250 12050 11501 10820 10129 9455 8873 8385 7971 7625 7342 7108 6944 6797

#

# Alt 10000

9100 9100 9300 9800 9950 9870 9680 9325 8897 8475 8018 7613 7230 6917 6630 6403 6213 6037 5913

#

# Alt 20000

5900 6000 6300 6750 7650 7930 7890 7675 7400 7117 6867 6646 6517 6425 6316 6283 6270 6250 6224

#

# Alt 30000

3720 3840 4090 4460 5120 5575 5800 5893 6034 6111 6194 6268 6379 6438 6490 6528 6562 6650 6667

#

# Alt 40000

2400 2470 2600 2840 3250 3500 3800 4182 4609 5083 5600 6054 6544 7042 7475 7910 8282 8655 8972

#

# Alt 50000

1325 1400 1560 1750 2150 2400 2650 3054 3578 4103 4622 5130 5764 6266 6748 7208 7594 7940 8255

#

# Alt 60000

700 750 860 975 1150 1275 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800

#

# Alt 100000

57 56 62 66 77 84 92 102 114 128 143 159 166 168 169 169 169 168 164

#

# THRST3 - THRUST AT FULL AB (THROTL = 1.05)

#

# Alt 0

22200 21420 22700 24240 26000 27000 28400 31600 33500 34400 34370 33495 31925 29790 27150 23985 20560 16855 12950

#

# Alt 10000

16000 15700 16860 18910 21075 22100 23319 24700 26450 28250 30100 31250 31315 30770 29495 27735 25600 23225 20690

#

# Alt 20000

10950 11225 12250 13760 15975 17100 18300 19750 21150 22350 23550 24150 24425 24290 23615 22680 21425 19875 18200

#

# Alt 30000

7050 7323 8154 9285 11115 12150 13400 15250 16600 17250 17850 18450 19700 20650 21300 22103 23003 18840 18355

#

# Alt 40000

4350 4435 4800 5400 6250 7100 8500 10100 11700 12400 12775 13125 13500 14432 15488 16432 17500 18703 19800

#

# Alt 50000

2500 2600 2835 3215 3950 4500 5057 6000 7000 7750 8000 8200 8300 8930 9434 9903 10400 11200 12030

#

# Alt 60000

1350 1400 1600 1800 2200 2450 2850 3400 4000 4350 4450 4500 4750 4803 4900 5033 5203 5300 5300

#

# Alt 100000

163 163 177 201 247 281 316 375 438 484 516 531 541 547 550 550 550 547 531

#

[Pilotasso]

Well that shut everybody up. :smilewink:

 

No it wouldnt, because weapon drag is goin to still PWN all perfomace improvements you might add. This issue wouldnt be as serious if we had lower drag factors for the missiles on board. Infact you would have less reason to complain with the missiles drag tweaked alone than tweaking the F-15 FM because you rarely do anything usefull with clean config anyway.

[britgliderpilot]

Something like this?

 

A load of performance estimation data.

 

#

 

I'm intrigued.

 

Where did all this come from?

[Pilotasso]

Falcon 4 LOL

[S77th-GOYA]

because you rarely do anything usefull with clean config anyway.

 

Sometimes, when I am winchester, I find that running home like a little screaming schoolgirl is very useful. And if missile drag is reduced without adjusting thrust, a MiG might very well catch a clean, running 15 if the MiG is just carrying a heater or two.

[D-Scythe]

Something like this?

 

#Title:F15C 22..

 

Can you post the output of the Dash 220 in Falcon 4.0's HFFM?

[Rhen]

Howdy Yo-Yo,

 

Thanks for showing up and answering questions. I've always wondered how you were using the time to climb charts to determine your flight envelope regarding the Eagle.

 

I must again point out that the charts are designed to use the T.O. (technical order - dash one) procedure for climb. This would be the following:

 

For all takeoffs:

 

Line up on runway configured with flaps down. Set brakes and run engines up to 80%. Release brakes/start timing and smoothly set takeoff power...

 

For afterburner takeoffs & Climbouts:

 

Set max, at 120KCAS, move stick to 1/2 stick travel and rotate to 10degrees at nosewheel liftoff speed. Hold 10 degrees until positive rate of climb (VVI and altitude increasing), raise gear & flaps. Maintain 350KCAS. Pitch as required to maintain 350 until M0.95, then maintain M0.95 or 40 degrees nose up until M0.95. Then maintain M0.95 until passing through desired altitude - to get time to climb to that altitude.

 

For Mil power takeoffs & climbouts, use same procedure as above except set military power and maintain 350KCAS. Then maintain 350KCAS until M0.9. Maintain until passing desired altitude - to get time to climb to that altitude.

 

Assumptions:

 

1) Takeoff and climbout technique conform to Dash 1 procedure.

2) Time to get to 350KCAS=30 sec. This is based on median time it takes for an F-15 to accelerate to 350 after takeoff.

3) Distance to get to 350KCAS=1NM for Burner takeoff, 2NM for Mil power takeoff.

4) You can mix/match - do an afterburner takeoff but a mil power climb to altitude.

5) For the charted times to be accurate, LOMAC must model the engine appropriately with respect to temperature and airspeed changes. That is:

a) The initial conditions must be compensated for - or just takeoff from a sea level base. Otherwise you must subtract time and distance of starting altitude. For example a takeoff from a base at 1,000ft MSL would require subtracting 3-6 seconds depending on AB/MIL power takeoff.

b) Standard day 59oF/15oC, 29.92mmHg/101.3kPa, with normal adiabatic lapse rate to altitude. Otherwise temperature corrections must be made.

c) Engine behaves correctly in climbout method selected MIL/MAX power climb.

 

What you've shown seems appropriate for a MAX power climb. I get close to the same numbers you do - within 6sec max. Distances also appear appropriate for the climb mode.

 

HOWEVER, have you looked at the performance of the aircraft in MIL power? It's severely ANEMIC! The time to climb is SIGNIFICANTLY longer than it would be IRL (more than 1.5 times greater) to get to 40,000 than the real jet at 39,000Lbs. The distances are 1.5 times greater as well. The combat ceiling at MIL power is reached earlier as well.

 

I would also like to point out that level flight acceleration at high altitude also appears off. Of course it's not quicker, it's quantitatively slower by 20%. This can be tested by taking a clean F-15 from M0.83 (to compensate for pylon drag) and accelerating a 39,000Lb Eagle at 40,000ft to M1.0, which should take about 25 sec, but actually takes 30.

Where does the problem lie? Perhaps it's in engine modeling/thrust output vs time or just plain thrust output. Perhaps it's in modeling mass vs acceleration. Perhaps it's in the drag numbers. Perhaps it lies elsewhere. Regardless there appears to be something amiss here.

 

While I respect your hard work and effort, saying the F-15 truly behaves the way it should is not quite correct, regardless of how it behaves in only one particular flight regime - MAX power climbs to altitude.

 

I would also like to point out that I can make the aircraft climb faster or slower, by varying climb technique. This is why it's a non-sequitur to believe that comparing the Strike Eagle to the vanilla Eagle will produce a logical correlation. It's essentially comparing two different aircraft with the same airfoil. The truth about modeling the Eagle, as you said, lies within the Dash 1 charts not in comparisons with the Strike Eagle. Implementing ALL of the aerodynamic properties within every one of the charts will simulate an Eagle better than taking one or two separately.

[TucksonSonny]

Can you post the output of the Dash 220 in Falcon 4.0's HFFM?

 

I don’t know about status of the hffm’s in the latest red viper.

I am still on hffm’s for CobraOne/BMS:

Anyway I remember in the past that I was helping (with testing) to make a patch for (correcting) the drag weapons loadout – values!

 

[cool_t]

What?

 

Hu?

 

I let you guys build it then Ill fly it.

 

:pilotfly:

[hitman]

I broke my F4 disk and my SP4 cd the other day on accident. Finding these are gonna be a big pain in the chopstick I just know it.