Key Points and Summary – In the early 1990s, Grumman proposed the ST-21 “Super Tomcat,” a radical upgrade to the F-14.
-This hypothetical jet would have featured powerful new engines enabling supercruise, greater fuel capacity for extended range, and advanced digital systems.
F-14D Tomcat Photo Onboard USS Intrepid. National Security Journal Photo.
F-14 Tomcat on Flight Deck at USS Intrepid Museum. Image Credit: National Security Journal.
Despite its compelling on-paper performance, the project was ultimately doomed. High costs, the F-14’s inherent maintenance complexity, and a shifting post-Cold War strategic environment worked against it.
-Ultimately, the rise of more versatile, cost-effective, and stealthy aircraft like the F/A-18 Hornet and the future F-35 made the fourth-generation Super Tomcat a technological dead-end.
The ST-21 Super Tomcat Was Never Built: Why?
In the early 1990s, the United States Navy was on the lookout for creative ways to extend the service life of the F-14 Tomcat platform. One proposal from Grumman would have seen improvements to the D variant Tomcat: the Super Tomcat for the 21st century, or ST-21.
An analysis of the proposed ST-21 aircraft is purely hypothetical: Grumman never produced the ST-21, and the aircraft is known only from a small handful of drawings and a notional model. But several improvements to the F-14D Tomcat design were anticipated.
One of the biggest improvements over the F-14D Tomcat would have been the proposed Super Tomcat’s engines, F110-GE-429 turbofan from General Electric. Modifications to that engine, found in some late-build F-16s and F-15s, would have given the jet that ability to supercruise without afterburner economically.
To feed the high-performance engines, the aircraft’s leading edges would have provided the jet with an additional 4,400 pounds of jet fuel.
Grumman would have incorporated a range of other improvements and optimizations to the aircraft aimed at increasing performance and reliability, as well as integrating more powerful radar and a digital cockpit.
Had it been realized, the Grumman’s proposed ST-21 would have been a very capable, multi-role naval fighter with a greatly expanded fuel capacity — and therefore range — over the then-baseline F-14D Tomcat.
F-14D Tomcat Fighter NSJ Original Image. Taken by Dr. Brent M. Eastwood.
F-14D Tomcat at Smithsonian In Washington DC. Image by Brent M. Eastwood/National Security Journal.
Some Challenges, Risks, and Program Sunset
Though the proposed Tomcat variant — essentially a new aircraft — would have been very compelling, several obstacles to the project ultimately led to its lack of development beyond the purely hypothetical phase. One of these was cost.
Bold upgrades to the platform that Grumman proposed would have been costly: a more advanced Tomcat would not have been an iterative improvement akin to the fighter’s A, B, and C variants.
Instead, it would have been an entirely different aircraft with extensive modifications to the airframe, new avionics, new engine integration, and other new technologies incorporated in the design.
The logistics of the F-14 Tomcat were very complex to begin with. The F-14’s variable-sweep wings and the robust airframe that supported them were maintenance-intensive, and an updated Tomcat design would not necessarily reduce the burden on maintainers.
An incremental performance gain — particularly in a post-Cold War world with little to justify the investment in an improved Tomcat — was a difficult sell.
The threat environment changed radically in the 1990s, too, and with that shift in the environment came an adjustment in defense priorities.
Modular platforms with an open systems architecture and lower life-cycle costs trumped the previous emphasis on exquisite platforms such as high-performance bombers and interceptors.
Put simply, there was little political appetite and few defense dollars available to even a highly capable F-14 derivative.
F-14 Tomcat. Image Credit: Jack Buckby/National Security Journal.
F-14 Tomcat Photo Taken on August 24 2025. Image Credit: Jack Buckby/National Security Journal.
The advent of stealth aircraft into American service also put the kibosh on the improved Tomcat, as the cost advantages of a clean-sheet naval fighter, the F/A-18 Hornet, prevailed.
In the long term, the Hornet had a great deal of potential to integrate future improvements and new technology, whereas an even higher-performance Tomcat likely wouldn’t have been able to incorporate new technologies in the future, a kind of technological dead-end.
Postscript: The ST-21 Super Tomcat Was Destined to Fail
Impressive though the purely hypothetical improved Tomcat would have been, that jet’s useful service life would likely have been rather limited.
With the advent of the F-22 Raptor following the U.S. Air Force’s Advanced Tactical Fighter program, and the advent of the Joint Strike Fighter program in the early-mid 1990s, cemented the future of fifth-generation stealth aircraft in within the United States military, and heralded a shift in combat aviation more broadly.
Although the United States held a monopoly on stealth aircraft for many years, the proliferation of stealth technology, particularly in China, where multiple stealthy aircraft are in development, and to a significantly lesser extent in Russia, means that non-stealthy aircraft will play an ever-decreasing role in manned combat aviation.
It is difficult to see how even an up-engined, more capable — but still fourth-generation — Tomcat would survive against aircraft of an entirely different generation.
Indeed, one only needs to look to the United States Navy’s fleet of F/A-18 Hornets and Super Hornets, which are being replaced by F-35 fighters, and the anticipated rollout of the F/A-XX, to see that there is decreasing deck space available on U.S. Navy aircraft carriers for non-stealthy aircraft.
At sea (Mar. 1, 2007) – Capt. Craig “Animal” Williams (front) in a F/A 18C Hornet (front) and Capt. Richard “Rhett” Butler (back) in an F/A 18C Hornet look up for a photo as they fly over USS Ronald Reagan (CVN 76). Capt. Williams, a 22-year Naval Aviator who graduated from the United States Naval Academy, was relieved as Commander, Carrier Air Wing Fourteen (CVW-14) by 21-year Naval Aviator, Capt. Butler, a graduate of the University of Kentucky during an aerial change of command ceremony. The Ronald Reagan Carrier Strike Group is currently underway in the Pacific Ocean on a surge deployment in support of U.S. military operations in the Western Pacific. Official U.S. Navy photo by Lt. Cmdr. Tam Pham
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So while the ST-21 could have been a remarkable navalized fighter jet, it would have faced inherent limitations, particularly in its ability to incorporate new future technologies, and survivability shortcomings when facing off against newer aircraft with robust radar-defeating stealth characteristics. It never left the drawing board.
About the Author: Caleb Larson
Caleb Larson is an American multiformat journalist based in Berlin, Germany. His work covers the intersection of conflict and society, focusing on American foreign policy and European security. He has reported from Germany, Russia, and the United States. Most recently, he covered the war in Ukraine, reporting extensively on the war’s shifting battle lines from Donbas and writing on the war’s civilian and humanitarian toll. Previously, he worked as a Defense Reporter for POLITICO Europe. You can follow his latest work on X.
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