수송기 DARPA, 지면효과익 수송기 "Liberty Lifter" 개발설계 계약 발주

[위종민]

DARPA가 지면효과익 수송기 개발 설계 계약을 GA와 Aurora Flight Sciences와 체결했습니다. 요구조건은 비행고도 상공 100피트 이하에서 수송중량 90톤 가량을 6,500해리 이상 떨어진 곳까지 옮기는 능력이라고 합니다. C-17 글로브마스터III와 크기 및 용량이 비슷한 대형 수상기가 될 것이며 시 스테이트4 (파고 1.25~2.5m)까지 이착륙이 가능하고 시 스테이트5 (파고 2.5~4m)까지 수상운용이 가능해야 하며 지면효과익 비행은 물론 최대 해발 10,000피트까지 비행이 가능해야 한다고 합니다. 1단계에서의 목표 수송량은 ACV 2대, 또는 20피트 컨테이너 6개네요. 

GA는 수상 안정성과 시키핑에 중점을 둔 쌍동형 중익 기체를, Aurora Flight Sciences는 전통적인 수상기 형태 컨셉을 제안했습니다. 

러시아와 한국과는 달리 미국에선 지면효과익이 빛을 볼 지 궁금해집니다. 

https://news.usni.org/2023/02/01/darpa-awards-contracts-for-long-range-liberty-lifter-flying-boat-design

DARPA Awards Contracts for Long-Range ‘Liberty Lifter’ Flying Boat Design

By: Sam LaGrone

February 1, 2023 7:45 PM

Artist concept of General Atomics bid for DARPA’s Liberty Lifter Program

The Pentagon’s emerging technologies research arm awarded two aviation companies contracts to develop seaplanes that would fly less than 100 feet off the ground and carry 90 tons of cargo more than 6,500 nautical miles, the Department of Defense announced Wednesday.
General Atomics, working with Maritime Applied Physics Corporation, and Aurora Flight Sciences, working with Gibbs & Cox and ReconCraft, each won contracts to start design and development work for a prototype Liberty Lifter cargo aircraft, according to the DARPA announcement.

“The planned Liberty Lifter demonstrator will be a large flying boat similar in size and capacity to the C-17 Globemaster III transport aircraft. Goals include takeoff and land in Sea State 4, sustained on-water operation up to Sea State 5, and extended flight close to the water in ground effect with the capability to fly out of ground effect at altitudes up to 10,000 feet above sea level,” reads a statement from DARPA.

Artist’s concept of Aurora Flight Sciences bid for DARPA’s Liberty Lifter Program

“Liberty Lifter will use low-cost manufacturing akin to ship fabrication in building a highly innovative seaplane capable of meeting DoD heavy lift requirements [100+ tons] that operates with runway and port independence.”

General Atomics was awarded $8 million cost-plus-fixed-fee contract award in support of DARPA’s Liberty Lifter program in November for the work, the company announced Wednesday. Neither Aurora nor DARAPA included the award to the Boeing subsidiary in their statements.

In the first phase of the contract, the two teams will develop an aircraft that will carry two Marine Corps Amphibious Combat Vehicles or six 20-foot-long cargo containers at just above the wave tops using the physics of the ground effect. Fixed-wing aircraft flying close to the behave like they’re riding on a cushion of air between the ground. Airplanes experiencing ground effect use less energy to move through the air at high speeds and in turn take less energy to fly.

Both companies have taken different approaches to their designs.

“The General Atomics team has selected a twin-hull, mid-wing design to optimize on-water stability and seakeeping. It employs distributed propulsion using twelve turboshaft engines,” reads the DARPA release.
“Aurora Flight Sciences point-of-departure design more closely resembles a traditional flying boat, with a single hull, high wing and eight turboprops for primary propulsion.”

Now, the two teams will set out on an 18-month period to refine the operational concepts and design for each proposed Liberty Lifter.

Artist’s concept of General Atomics bid for DARPA’s Liberty Lifter Program

“Phase 1 will transition into Phase 2 in mid-2024 with continued detailed design, manufacturing, and demonstration of a full-scale Liberty Lifter X-Plane. DARPA anticipates teaming with one or more DoD Service and international partners for those activities and further development of the Liberty Lifter concept into an operational vehicle,” DARPA’s statement reads.

DARPA’s effort isn’t the first time a government has tried to create a ground effect vehicle for military applications.

The Soviet Union experimented with ground effect vehicles with its ekranoplan program – high-speed cargo aircraft for the Baltic and Black Sea fleets, but the platforms were largely sidelined in the 1980s.

Perhaps the most famous ground-effect craft was the massive 400,000-pound Hughes H-4 Hercules cargo plane that flew 70 feet above the ground for about a mile in 1947. The so-called Spruce Goose was developed in conjunction with the Pentagon for a similar mission as the Liberty Lifter – transporting cargo across vast distances faster and at less risk from attack than a ship.

[백선호]

1950년대의 R3Y 생각이 나네요.

https://en.wikipedia.org/wiki/Convair_R3Y_Tradewind

[위종민]

이런 기체도 있었네요. 괌 이서의 중국 A2/AD 범위 안 소규모 도서지역에 대한 신속한 화물수송이 목적일 듯 한데 결과가 어떨 지,,

[백선호]

156톤의 더 큰 것도 있었죠.

https://en.m.wikipedia.org/wiki/Saunders-Roe_Princess

[김용우]

러시아는 저 컨셉으로 바랬던게 엄청나게 빠른 폭격기와 수상전투함 사이에 있을 무언가를 원했던거였지만 미국은 대형수송기와 화물선박 사이의 무언가를 만들려고 하는걸로 보이는데 미국쪽 컨셉이 좀 더 수요가 있을거 같군요.

[위종민]

일단 컨셉 개발에서 쓸만한 게 나온다면 미군부터 관심을 가질 듯 합니다. 우리나라도 갖고 있으면 쓸만한 기체일 듯 하고요.

[Black Knights (윤재산)]

록히드나 노스롭그루먼은 관심이 없었나보군요?