To date, there exists no definitive conceptual design on the Liberty Lifter although some preliminary graphical renderings were created decades ago.
Naval News Comments
One of the “Liberty Lifter’s” DARPA X-Plane Requirement is to transport two U.S. Marine Corps’ armored Amphibious Combat Vehicles (ACV), each with a gross weight of 67,500 pounds (30,617 kilograms) or 33.75 tons. This Requirement for the “Liberty Lifter” to carry two ACVs results in a total vehicle cargo weight of around 67.5 tons. This carrying weight is smaller than the initial DARPA WIG cargo plane rating of 100+ tons, but is about the cargo-carrying weight of a C-17 rated at 72.6 tons (160,000 pounds).
Each ACV has a crew of three and can carry thirteen combat-equipped Marines in the rear. Thus, a single Liberty Lifter, could in theory, deposit a Marine platoon almost anywhere on land and at sea as the DARPA Liberty Lifter video shows two ACVs being driven right onto the beach from inside the seaplane’s twin fuselages. With flying speeds (much) greater than the ACV’s swimming speeds and that of U.S. Navy landing craft, the Liberty Lifter should expand the mobility of any amphibious assault in certain uncontested and/or permittable environments.
How exactly the Liberty Lifter will achieve its Requirements is the goal of this X-Plane program. Some concepts call for a huge boat-like hull whereas others have two wing-mated fuselages similar to the World War Two P-38 fighter or the Scale Composites’ Stratolaunch designs.
The U.S.’s Defense Advanced Projects Research Agency (DARPA) replied to Naval News’s Questionnaire on May 24, 2022.
Naval News: Is DARPA looking for a full-scale Liberty Lifter prototype to fulfill the requirement or a fractional scale mockup?
DARPA: DARPA intends to design, build, float, and fly a full-scale Liberty Lifter demonstrator.
Naval News: Does DARPA have a price goal range for the Liberty Lifter?
DARPA: Liberty Lifter’s price goal is to demonstrate production costs less than half of those for comparable military airlifters.
Naval News: Does DARPA intend for the Liberty Lifter to be armed with wing pylons or for armed cargo drops [such as cruise missiles shoved out of the rear ramp]?
DARPA: DARPA’s Liberty Lifter is a technology demonstrator focused on the aerodynamic and hydrodynamic challenges of a seaborne strategic lifter. We don’t intend to include wing pylons for the demonstrator.
Naval News: Is the Liberty Lifter open to international competitors?
DARPA: The DARPA team has solicited and evaluated a wide range of technical approaches and concept designs for Liberty Lifter, including some from international firms. We are currently in Source Selection reviews and cannot comment further on specific competitors or proposals at this time.
Naval News: Which branch service will Liberty Lifter most likely go towards if built?
DARPA: DARPA is actively engaged with the USMC, U.S. Navy, U.S. Air Force, and U.S. Army. Partnership with one or more Services for production and test of the Liberty Lifter demonstrator is anticipated later in the program’s execution. At the completion of DARPA’s test and demonstration phase, transfer of the Liberty Lifter demonstrator vehicle to a Service partner for further experimentation is envisioned.
Naval News: What are the criteria for testing to achieve [Liberty Lifter] X-Plane success?
DARPA: DARPA’s [Liberty Lifter] X-Plane program will be considered a success if we demonstrate a unique capability via floating & flying a large seaborne airlift platform.
Naval News: How many crewmembers and can the Liberty Lifter be refueled in flight?
DARPA: Crew size is to be determined based on performer designs and requirements for safe and efficient operation of the Liberty Lifter demonstrator. There is no requirement for in-flight refueling, either as receiver or tanker, for the DARPA demonstrator, but it is a potential capability for a future production vehicle if the Services deem it desirable.