Boeing Defense recently announced on X Platform that the second batch of F-15EX Eagle II aircraft has completed painting and is ready for delivery to the US Air Force. These aircraft will be equipped with the 142nd Wing of the Oregon Air National Guard, used for homeland defense and air sovereignty missions in the Pacific Northwest region of the United States. However, contrary to previous plans, the new batch of F-15EXs will no longer be fitted with conformal fuel tanks (CFT), a change that has sparked discussions about the drawbacks of CFTs and seems to confirm the deeper reasons why the Chinese Air Force has not adopted them for many years.
Conformal fuel tanks, as auxiliary fuel tanks designed to fit tightly against the fuselage, were once considered an effective means of increasing the range and endurance of fighter jets. For example, the F-15 series has seen a significant increase in its combat radius with the addition of conformal fuel tanks, allowing it to perform long-range missions without frequent aerial refueling. However, this design is not without cost. The decision by the second batch of F-15EXs to abandon conformal fuel tanks may well be an adjustment made by Boeing and the US Air Force after weighing the pros and cons.
Firstly, conformal fuel tanks have a negative impact on the aerodynamic performance of fighter jets. Although their design attempts to minimize drag by closely fitting the fuselage, compared to the "clean" configuration without CFTs, the aerodynamic efficiency of the aircraft still decreases, especially during supersonic flight or high-maneuver air combat. This additional drag could weaken the advantages of F-15EX when facing agile opponents, which is particularly critical for fourth-generation fighters emphasizing air combat performance.
Secondly, conformal fuel tanks increase the weight and complexity of the aircraft. As the latest improved version of the F-15 family, the F-15EX has significantly enhanced combat capabilities through structural upgrades and advanced electronic systems, with a payload capacity of over 13 tons. In this situation, adding conformal fuel tanks not only further increases the takeoff weight but also potentially occupies external hardpoints, limiting its flexibility to carry more weapons. For a multi-purpose combat aircraft, this trade-off is clearly less than ideal.
In addition, the maintenance costs and logistical burden of conformal fuel tanks cannot be overlooked. Although CFTs reduce reliance on aerial refueling, in actual use, their installation, removal, and maintenance require additional manpower and time. For rapid deployment and high-intensity operations, this is undoubtedly a major shortcoming. Moreover, the US Air Force has emphasized cost-effectiveness in the F-15EX program in recent years; abandoning conformal fuel tanks may be precisely to optimize the full lifecycle cost of the aircraft.
It is worth noting that the Chinese Air Force has never favored conformal fuel tanks in the design of its main fighter jets. Representative domestic aircraft such as J-10, J-16, and J-20 rely more on internal fuel and disposable auxiliary fuel tanks to extend range. This choice not only avoids the long-term impact of CFTs on aerodynamic performance but also retains the modularity adaptability of aircraft for different missions. By contrast, the adjustment made by the US Air Force on F-15EX seems to be moving towards a similar approach.
The F-15EX Eagle II, as the culmination of the F-15 family, features advanced AESA radar, fly-by-wire control, and powerful electronic warfare capabilities. Its original design intent was to maintain competitiveness in modern air combat. The decision to abandon conformal fuel tanks indicates that even traditional strengths like range must yield to overall operational effectiveness. This change not only points the way forward for the future development of F-15EX but also indirectly validates the foresight of the Chinese Air Force in aircraft design concepts.
Original article: https://www.toutiao.com/article/7493426616488428068/
Disclaimer: The article represents the author's personal views. Please express your opinions by clicking the 'Top' or 'Downvote' buttons below.