Recently, Lockheed Martin's Skunk Works released concept drawings of the Next-Generation Air Refueling System (NGAS) program stealth tanker, also known as KC-Z, which is designed to replace the KC-2030s and KC-46 tankers in the 135s. The KC-Z tanker looks smaller than the model it will replace, and the picture shows it refueling the F-35A using a hard pipe system.
Concept art originally published by Aviation Week, lambda wing, tilted twin tails. The engines (there could be two) were buried in the fuselage, the air intakes were located under the root of the wing (underarm air intakes), and possibly in the rear there were flat nozzles.
图为Lockheed Martin早期概念模型
While the design in the diagram is conceptual (Lockheed Martin released another completely different concept last year), it is interesting to note that the concept of low observability is also making its way into high-value aviation assets. However, similar to the next-generation air superiority program that we have mentioned many times, the concept map may not be representative of the real design being developed.
Last year, the U.S. Air Force issued an RFI asking the industry to provide a new tanker capable of surviving in counter-airspace, mentioning that the Air Force is interested in innovative solutions of various sizes and performance levels that could potentially meet tight mission requirements. The Air Force then began to analyze alternatives.
The picture shows the Boeing conceptual model
Next-generation in-flight refueling system NGAS
NGAS will be the third of three increments in the Air Force refueling program: increment 1 is represented by the KC-46 program, and increment 2 is called KC-Y or Bridge Tanker. The new tankers will be able to operate closer to the front line to better support fighters, while more "traditional" tankers will be used at safer distances.
Adm. Mike Minihan, commander of the Air Mobile Command, said earlier this year, "It's not just an airplane. It's a system, so it's not one-size-fits-all. I don't intend to develop a fleet that will have to deal with a variety of threat environments."
The photo shows the Boeing KC-46
Minihan previously said he envisioned the tanker as part of NGAS in three roles. The majority of in-flight refueling missions will be performed by "traditional" tankers such as the KC-46 in a non-confrontational environment, while transitional tankers will perform missions closer to combat due to increased survivability and connectivity.
The last type, possibly the KC-Z, will perform high-end tasks in the same combat area as the fighter, it needs to be small and survivable. As a result, it requires more self-protection and advanced networks than existing types to address threats posed by potential adversaries to high-value aircraft such as tankers, while still being able to perform in-flight refueling missions.
Minihan said the planes could do much more than just refuel. In fact, he listed the open architecture, autonomy and combat management features that the new aircraft could contain, among other things. Even before the NGAS is put into service, some of these features may work on the KC-46.
However, the new tanker program has not yet been finalized. Last year, the Air Force said it would purchase only 75 tankers as part of the upcoming Bridge Tanker and push for a faster NGAS deployment. To be sure, funding will play an important role in these programs, since the Air Force is already working on such large projects as the B-21 Raider and NGAD, and the new tanker needs to be deployed "without bankrupting the Air Force."
Features of the KC-Z stealth tanker
1. Concept renderings of Skunk Works' new stealth tanker show that the design of the aircraft has a very wide planar shape, with larger-cut wings with some lambda wing features. The narrow front fuselage section protrudes at the front, and a relatively small outward-sloping twin vertical tail can be seen. The wide wings can accommodate large quantities of fuel to support in-flight refueling missions. Under the junction of the left wing with the middle fuselage, a tightly bonded engine air intake can be seen. Stealth designs typically bury the engine deep inside the main engine and take in air from the air intake through serpentine ducts to help keep the radar signature to a minimum, especially from a critical forward perspective.
2. The aircraft also has a clear jawline that wraps around the front of the aircraft and blends into the wings, with the trapezoidal upper and lower fuselages meeting at its apex – another stealth feature. The front cockpit has a large windshield of two (or three), and the rear cockpit has another overhead conformal canopy. The width of the fuselage can be seen in comparison with the F-35 below, which indicates that the aircraft will have a crew of two.
3. One of the most interesting features depicted in renders of Skunk Works' new tanker is what looks like a centrally mounted aerial refueling pole under the main fusel. All aircraft built to date with booms, at least as far as we know, have this system installed in the tail section. In this case, the new boom position makes sense, because when not in use, it would very much like to be able to store inside, or at least flush with the bottom of the fuselage, to keep the tanker as discreet as possible.
4. Loma and Boeing have also proposed similar stealth tanker schemes before.
The picture shows a variety of stealth tanker designs from Lockheed Martin