F-16 vs Mig-29 energy maneuverability from test report

Agreed, it will never be a fair fight but how would the F-16 match up against the ... ?
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gta4

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Unread post11 Feb 2018, 15:29

In this thread, I will use F-16's aerodynamic data (from test report) to do the following:
1) convert its maximum sustained G factor to 5000 m, Mach 0.9 (F-16's manual does not show this performance)
2) calculate its maximum SEP at sea level (F-16's manual does not show this performance)
3) and pit it against Mig-29, its all-time-rival (data from official Mig-29 aerodynamic manual, in Russian)

Calculation standard:
F-16C block 50, with pilot and 1174 kg fuel (which gives it the same after burner duration as a Mig-29A with 1500 kg fuel, as Mig's performance curve is given with 1500 kg fuel in its manual).
When comparing sustained g, both aircraft are clean. When comparing SEP, viper is equipped with 2 Sidewinders while Mig is clean, to make the result more convincing.

Total mass = 8734 kg (operational weight) + 1174 kg (fuel weight) + 120 kg (pilot) = 10033 kg.
block50 empty weight.jpg

(In F-16's manual there is another empty weight number saying 20000lbs but there is also a mark saying this number is not accurate enough for performance calculation, while 19261 lbs is used for performance calculation. So 19261 lb is used here.)
viper's drag polar is from AGARD CP-242 flight test report:
Correlation of F-16 aerodynamics and performance predictions with early flight test results, Webb, T.S., Kent, D.R., Webb, J.B.
and fulcrum's drag polar is from its aerodynamic manual.
(plotted in excel for clarity)
F16 vs Mig29 drag polar.jpg

Installed thrust is from HFFM data, simulated by Mav-JP and Raptor one:
ge129.JPG

With interpolation, it is easy to acquire the thrust at 5000m, M 0.9 to be 25834 lbs (11721 kg, 114870 N).

Sustained turn at 5000 m, M 0.9:

In sustained turn, thrust = drag:
114870 = 0.5 * Cd * density * speed^2 * wing area
where
density = 0.763 kg / m^3
speed = 288.47 m/s (0.9 mach at 5000 m)
wing area = 27.87 m^2 (300 square feet)
So:
Cd = 2 * 114870 / (density * speed^2 * wing area) = 0.135
The corresponding Cl from drag polar is 0.84. The required AOA is about 9 degree.
Lift / Drag = Cl / Cd = 0.84 / 0.135 = 6.222
Lift = 6.222 * Drag = 6.222 * thrust = 6.222 * 114870 = 714721.14 N
The normal contribution of thrust is
Thrust * sin(AOA) = 18042 N
Total normal force = 714721 + 18042 = 732763 N
Normal load factor = Total normal force / total mass / 9.8 = 732763 / 10033 / 9.8 = 7.45 g
Mig-29A 's manual shows a sustained load factor of 6.6g at M0.9, 5000m:
29 sustained at 5000m.jpg


A side product:
It is easy to verify that when both jets execute a 9G turn with ENGINES TURNED OFF, at the same altitude and speed, Fulcrum's energy bleeding rate is noticeably higher than the viper. This is due to the higher Lift/Drag benefited from viper's shape design.

SEP at sea level, M 0.9:
Sep = (thrust - drag) * speed / gravity
Where
thrust = 166742 N
drag = 0.5 * Cd0 * density * speed^2 *wing area
Cd0 = 0.025 (with 2 sidewinders)
density = 1.225 kg / m^3
speed = 0.9 * 340 = 306 m/s
wing area = 27.87 m^2
gravity = (mass + 2 sidewinders) * g = (10033 + 2*87) * 9.8 = 100028.6 N
Drag = 39618 N
Sep = (166742 - 39618) * 306 / 100028.6 = 388m /s > 1200 ft / s

Wait! Isn't this number too...ooo astonishing?
Let's verify it with F-16C block50's flight manual.
The closest configuration on the manual is 22000lbs, clean. Take a look at the left figure:
16 vs 29 sep.jpg

It can achieve 1200 ft /s while still maintaining a 7.5 deg / sec turn!Keep in mind, normally SEP only refers to straight line flight. It is a lot harder to achieve high SEP in a turn due to elevated drag. So our calculated straight line SEP (> 1200 ft /s) is verified.
By contrast, Mig-29A can only achieve 345m/s clean, and 330m/s with 2 R-60s (a small missile which is even smaller than sidewinder), both in straight line flight.
Conclusion:
F-16C block 50 has higher sustained G than Fulcrum A, and bleeds less energy in a high G turn, at medium altitude, subsonic to transonic regime. where dogfights are most likely to take place. Viper also has higher SEP in a turn than a Fulcrum in straight line flight!

We know Fulcrum is already pretty good especially in terms of SEP. It is even better than Su-35BM (check Su-35's official maneuverability data). However...
Last edited by gta4 on 12 Feb 2018, 00:45, edited 1 time in total.
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garrya

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Unread post11 Feb 2018, 17:01

gta4 wrote:1) convert its maximum sustained G factor to 5000 m, Mach 0.9 (F-16's manual does not show this performance)

I think maximum sustained load factor can be found on al doghouse plot
gta4 wrote:We know Fulcrum is already pretty good especially in terms of SEP. It is even better than Su-35BM (check Su-35's official maneuverability data). However...

How come, can you explain?
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marsavian

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Unread post12 Feb 2018, 12:14

From E-M diagrams the F-16A has the sustained 7+g performance at the height and weight you suggested. At full fuel weight and draggy the F-16C can do it too at 10K ft altitude which kind of all implies your calcs are on the money.
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gta4

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Unread post12 Feb 2018, 13:42

Well that should be true because I also verified the sep data with your flight manual. They are pretty close.

By the way, drag index=50 means 6 amraams+pylons...
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Unread post13 Feb 2018, 14:42

garrya wrote:
gta4 wrote:1) convert its maximum sustained G factor to 5000 m, Mach 0.9 (F-16's manual does not show this performance)

I think maximum sustained load factor can be found on al doghouse plot
gta4 wrote:We know Fulcrum is already pretty good especially in terms of SEP. It is even better than Su-35BM (check Su-35's official maneuverability data). However...

How come, can you explain?


SEP value normally reaches its peak at Mach 0.9.
SU-35's aerodynamic efficiency at Mach 0.85-0.9 is significantly lower than Mig-29. The Oswald efficiency factor of Su27 is only 0.71, compared to Mig's 0.87.
Image
You can check the author's autobiography. It is the designer of Su25 and Su27/30.
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eloise

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Unread post13 Feb 2018, 17:57

gta4 wrote:
By the way, drag index=50 means 6 amraams+pylons...

F-16 with 6 AMRAAM has drag index around 40 because DI=0 included wing tip missiles already and wet pylons of 370 gals tank went with them

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