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<strong>Mig</strong>-<strong>21</strong>-FM-Identification-Rev. 14<br />
Now compare this analysis with one where the difference between the value read in the manual and<br />
the one predict by the model is very low: let’s chose 750 Km/h (IAS) at 1,000m (Mach 0.646)<br />
The level flight acceleration curve analysis requires an Excess Specific Power of 357 ft/s giving a<br />
thrust of 12,437 lbs.<br />
The flight model (with the hypotheses used for our 3,000m computation) and this thrust value give:<br />
- AoA = 20.6 deg<br />
- C x = 0.084714<br />
- C z = 0.51998<br />
- Ng = 3.25 (+2%)<br />
The sustained load factor is said (in manual) to be 4.15g that can be reached (with the hypotheses used<br />
for our 3,000m computation) with:<br />
- AoA = 20.16 deg<br />
- C x = 0.081746<br />
- C z = 0.50883<br />
- Thrust = 11,844 lbs (-3.5%)<br />
We can see that the flight model is valid (2%) for mach number close to 0.640 and AoA close to <strong>21</strong><br />
deg at 1,000m but less accurate at 3,000m (9%)<br />
Maximum After-Burner Power, Altitude of 5,000m<br />
Vcas<br />
(Km/h)<br />
Vcas<br />
(Kts)<br />
Mach<br />
Sustained<br />
Ng<br />
(read)<br />
Sustained<br />
Ng<br />
(computed)<br />
Error<br />
500 270 0.548 2.22 2.36 6%<br />
550 297 0.600 2.47 2.61 5%<br />
600 324 0.651 2.73 2.85 4%<br />
650 351 0.702 2.97 3.07 4%<br />
700 378 0.754 3.19 3.34 5%<br />
750 405 0.805 3.48 3.58 3%<br />
800 432 0.856 3.72 3.74 1%<br />
850 459 0.908 3.85 3.82 -1%<br />
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