Comparing the Viper Block 50/52+ versus the Gripen E – July 2013 Part Two

‘Manueverability and Vertical Performance’
One aspect of both these planes I wanted to take a look was their maneuvering capability. This aspect is important during Within Visual Range (WVR) combat which I think will still be important for fighter aircrafts for a long time to come. For this I wanted to take a look at their WING LOADING (WL), and THRUST-TO-WEIGHT RATIO (TTWR).

“Wing Loading” is simply the amount of the weight the wing supports during flight, and is expressed in weight per area, or in the metric system, kg/m^2. This is computed by: (Wing Area divided by Weight)[1]. This is an important indication of an aircraft’s maneuverability in the horizontal plane as the lower the wing loading, the tighter the radius of a turn an aircraft can do at any given speed, and vice versa, the higher the WL, the wider the radius of a turn an aircraft can do.

“Thrust-to-Weight Ratio” means how much power the aircraft has compared to its weight, and is expressed by a simple number. This is computed by: (The maximum thrust of the aircraft’s engine divided by weight)[2]. This is also important both in the horizontal and vertical plane as it shows an aircraft’s ability to maintain speed during vertical turning maneuvers, and also show how fast an aircraft can accelerate when it is flying vertically straight up. The higher the TTWR means the more power the aircraft has available compared to its weight, and vice versa, the lower the TTWR means the less power the aircraft has available compared to its weight.

Data for the F-16C was derived from this website (http://www.fighter-planes.com/info/f16.htm), while data for the JAS-39E was derived from this reference (https://rhk111smilitaryandarmspage.files.wordpress.com/2013/07/67obo7.jpg). The following considerations were made:
– The F-16C has the advantage of using Conformal Fuel Tanks (CFT), and data with and without these tanks are presented for it. The CFTs will be discussed more in detail in the next section.
– Weights with 100% internal fuel was used to try to simulate the aircrafts going into combat with full internal fuel after dropping their External Fuel Tanks.
– The weights of the armaments were not included as the RATIOS and DIFFERENCES BETWEEN BOTH AIRCRAFTS will remain the same if they will be armed with the same type and same number of armaments.

Take note that all these data are just estimates, as the raw data taken from various sites themselves were probably just estimates also. So here are the selected raw and computed data:
(Data highlighted in yellow are for the F-16C with CFTs)
2013-09-05_Gripen1

* SUMMARY:
– TTWR difference: 7-19% more in favor of the F-16
– WL difference: 21-36% less in favor of the JAS-39
+ This means than during vertical turning maneuvers, the Gripen will lose airspeed at a rate of 7-20% more than the Viper
+ When flying straight up or diving straight down, the Viper will always be able to outrun the Gripen, but the reverse is not the same, the Gripen will not be able to outrun the Viper.
+ The Gripen however will always be able to turn inside of a Viper by virtue of its significantly lower WL
+ Overall, I would say Gripen has the advantage as its WL advantage is greater than its TTWR disadvantage to the Viper. If you get the difference between the Gripen’s WL advantage (21-36%) and the Viper’s TTWR advantage (7-19%), the result shows the overall maneuverability advantage of the Gripen to the tune of 14-17%.

‘Payload and Range’
Next aspect I wanted to look at was the Payload (weight each aircraft can carry externally), and Range of each aircraft. For Range, I wanted to use the concept of INTERNAL FUEL FRACTION (IntFF), which is simply the weight of the internal fuel the aircraft compared to its maximum weight, and is expressed by a simple number. Formula used is: (Maximum internal fuel capacity divided by maximum take off weight)[3].

IntFF I think is a better way to compare the range of at least 2 aircrafts as it is something more tangible and transparent as anybody can just compute it and see where it comes from, as opposed to just using the ranges provided by sources as you don’t necessarily know what involved the computation of those ranges.

Of course the ranges of both aircrafts can be extended using External Fuel Tanks (EFT) and/or In-Flight Refuelling (IFR), but they both have drawbacks. EFTs means the space and weight allocated for weapons will instead be used to carry fuel, meaning less space (i.e. on pylons) and weight for weapons. They also increase the Radar Cross Section (RCS) of an aircraft as they are large and bulky. IFR means you need to allocate a certain time and safe space to do the IFR as you just can’t do it in the middle of a battle.

The F-16 has the advantage because it has Conformal Fuel Tanks (CFTs), and these allow the aircraft to have more fuel (approximately 1,363 kg more) without allocating less space for weapons (i.e., doesn’t have to occupy a pylon), and they also will not increase an aircraft’s RCS significantly since they are “blended” into the aircraft’s body. The only main penalty of using CFTs is less weight allocated for weapons. Data with and without CFTs are used for the F-16.
(Data highlighted in yellow are for the F-16C with CFTs)
2013-09-05_Gripen2

* SUMMARY
– IntFF difference: Favors the Gripen by 26% if the Viper doesn’t carry CFTs, and favors the Viper by 14% if it carries CFTs
– Payload difference: Favors the Viper as it can either carry either the same payload if it carries CFTs, or can carry 22% more load if it doesn’t carry CFTs
+ Here the Viper is the winner, as it can either carry the same load 14% further if it uses CFTs, or it can carry 22% more load at a lower range if it doesn’t use CFTs

(End of Part Two)

SOURCES:

[1] Wing loading, http://en.wikipedia.org/wiki/Wing_loading

[2] Thrust to Weight ratio, http://en.wikipedia.org/wiki/Thrust_to_weight_ratio

[3] Fuel Fraction, http://en.wikipedia.org/wiki/Fuel_fraction

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7 thoughts on “Comparing the Viper Block 50/52+ versus the Gripen E – July 2013 Part Two”

    1. Nope. “Thrust-to-Weight” ratio is computed as “Engine Thrust” (for the Gripen 9,993 kgf) divided by the (in this case) “Empty Weight plus Weight of Maximum Internal Fuel” (for the Gripen is 10.360 kg), and the answer is 0.96.

  1. Sorry, I wrote wrong it should reade:
    F-16C Block 50 has a combat radius of 295 nmi with only internal fuel.
    JAS-39E Gripen has a combat radius of 700 nmi with 290 gallon center tank, incl. 30 minutes on station.

    1. If they really are going to retire that many F-16s, it is possible some of it may end up with the Philippines. But concerns are the condition of those planes. The Philippines just isn’t very good at maintaining aircraft requiring frequent parts replacement. We’ve seen this happen with the F-5As, then with the S-211s …

      We actually bought A LOT of 2nd hand F-5As during Ramos’ time, around 10 or so, I think, but we just couldn’t keep them in the air …

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