Reaction Engines公司設想的“云霄塔”（The Skylon）概念太空飛機，有望采用該公司的SABRE發動機技術。圖片由BAE Systems提供

忘了可重復使用火箭吧。英國軍工巨頭BAE系統公司剛剛向一種有望顛覆航天經濟學的新型飛機引擎投入了3200萬美元資金。

如果說眼下對于商業航天領域有什么普遍看法的話，那就是SpaceX和Blue Origin這樣的精益型行業新星正在借助新的技術和商業模式超越這個領域中的傳統企業，比如波音、洛克希德-馬丁和Aerojet Rocketdyne。

不過，作為歐洲最大國防承包商和徹頭徹尾的老牌航天企業，BAE系統公司投入了3000萬美元的技術可能把這些“攪局者”攪個底朝天。

BAE收購了英國小型技術公司Reaction Engines兩成股份。兩公司高層表示，Reaction Engines的協同吸氣式火箭發動機（SABRE）概念可能在航天動力領域再次引發革命。如果研制成功，這種噴氣/火箭混合發動機就可以讓飛機從普通跑道上起飛，然后以20馬赫以上的速度進入空間軌道，也能讓它像普通飛機一樣在跑道上著陸，而且自始至終都只使用自身的動力。

有了這種可重復使用的太空飛機，發射衛星以及向太空輸送其他貨物的成本估計有望下降90%；同時，以它為基礎，人們還能開發出可在四小時內飛抵世界上任何角落的客運飛機。BAE高層相信，該公司管理復雜空天研發項目的能力可以在2025年之前把Reaction Engines的技術從概念變成飛上天空的原型機。

Reaction Engines董事總經理馬克?托馬斯說：“看看其他可重復使用太空飛機的概念就會發現，他們依靠的動力不一而足，有火箭，有噴氣發動機，也有沖壓式噴氣發動機。我們拿出來的方案則把所有最好的元素都納入了一個動力系統。所以，我覺得目前我們遙遙領先。我還沒有看到任何能直接跟我們競爭的東西?！?/p>

按照設計，SABRE引擎可以像常規噴氣發動機那樣吸入空氣來工作。在這個階段，它可以讓飛機加速到5馬赫，也就是音速的5倍（時速超過3800英里，或6120公里）。然后，這種引擎可以“變身”為火箭發動機，把飛機送入太空。返還地面時，這種引擎還能“變回來”，用傳統的噴氣動力讓飛機在普通跑道上降落。同一臺發動機可以反復使用，因而不需要為安裝垂直火箭發射塔投入資金，就連SpaceX設想的可重復利用火箭發射塔的翻新費用都省了。

催生SABRE引擎的點子最早出現在30多年前。但基礎領域的一些技術障礙讓這個概念一直停留在紙上談兵階段，比如說，其中的一大問題是怎樣讓發動機充分散熱，以免自燃。Reaction Engines的工程師取得的關鍵性技術突破之一就是熱交換器，它可以在不到1秒鐘時間里讓發動機的進氣溫度從1800華氏度（約982攝氏度）降至零度以下。這樣，SABRE發動機的飛行速度就能超過常規噴氣發動機。

BAE航天業務工程主管克里斯?奧勒姆指出：“這可能從根本上改變人們航天的方式?！彼J為，如果能達到設計目標，這項技術就有望帶來一種新的飛機發動機，而且在飛行速度和性能上都要強得多。

同時，對BAE來說，這項技術能讓該公司在不斷增長的航天市場謀得關鍵的立足之地。雖然BAE北美公司確有相當數量的航天業務，比如衛星零部件制造之類，但它的商業航天發射業務尚未形成規模。奧勒姆說：“我們對這個市場很感興趣，而且正打算用另外一種方式開展業務。我們沒有隨波逐流，而是在尋求突破，或者說尋找一種新的東西?！?/p>

如果BAE能幫Reaction Engines的工程師把SABRE引擎送上天，它就有可能成為BAE正在動力領域尋找的革命性突破。關鍵在于，借助BAE提供的3200萬美元資金，Reaction Engines還可以從英國政府那里獲得9000萬美元的研發撥款。作為協議的一部分，BAE將向Reaction Engines派遣一名董事，并成為后者的首選供應商。作為非上市公司，Reaction Engines在對SABRE引擎進行大規模測試和開發時還要依靠BAE的支持。

兩家公司計劃先建造用于地面試驗的原型機，并在2020年之前點火測試，隨后在2025年以前完成原型機試飛。如果一切順利，配備SABRE引擎的太空飛機就有望在2030年之前飛上太空，然后返回地面。

那么，超高速點對點客運，或者說在四小時內飛抵地球上任何角落的前景如何呢？Reaction Engines董事總經理托馬斯說，有了這樣的技術，人們當然有可能做到這一點。但考慮到安全以及技術方面的多個因素，短期內更為實際的目標是讓太空飛機以25馬赫的速度定期往返于空間軌道和地面之間。

托馬斯表示：“目前許多人都熱衷于點對點客運，在四小時內到達世界上任何地方的想法總會讓人興奮不已。但這是個巨大的挑戰，而且和航天相比，這樣做的難度絕對要高好幾個數量級。最近我還對一位澳大利亞人說，可惜的是，飛往澳大利亞比飛向太空還難。”（財富中文網）

譯者：Charlie

校對：詹妮

The Skylon, a conceptual spaceplane envisioned by Reaction Engines, could one day be powered by the company's SABRE engine technology. Courtesy BAE Systems

Forget reusable rockets. BAE Systems just invested $32 million in a new type of aircraft engine that could upend the economics of spaceflight.

If there’s a popular narrative in the commercial spaceflight industry right now, it’s one of lean upstarts like SpaceX and Blue Origin tapping new technologies and business models to outmaneuver their legacy aerospace counterparts like Boeing BA -0.02% , Lockheed Martin LMT -0.90% , and Aerojet Rocketdyne AJRD 0.47% .

But BAE Systems BAESY 0.63% , Europe’s largest defense contractor and a legacy aerospace company through and through, is betting $30 million on technology that could disrupt those disruptors.

BAE has taken a 20% stake in Reaction Engines, a small British technology company whose conceptual SABRE engine technology could drive the next revolution in aerial propulsion, company executives say. If it works, the hybrid jet/rocket engine could launch an aircraft from a traditional runway, power it all the way to orbit at more than 20 times the speed of sound, and bring it back for a conventional runway landing—all under its own power.

Such a reusable spaceplane could trim the cost of launching satellites and other cargo to space by an estimated 90% and lay the groundwork for passenger aircraft that could reach any point on the planet within four hours. BAE executives are confident that the company’s acumen for managing complex aerospace R&D programs can take Reaction’s technology from concept to prototype to the sky by the middle of the next decade.

“When you look around at other concepts for reusable spaceplanes they rely on multiple kinds of propulsion—rockets, jet engines, ramjets,” Mark Thomas, managing director of Reaction Engines, says. “What we’ve achieved here is a combination of all of those best elements in a single propulsion system. So I think we’re well ahead of the game here—I’ve not seen anything that’s a direct competitor.”

As designed, the SABRE engine would power an aircraft up to Mach 5—that’s five times the speed of sound, or more than 3,800 miles per hour—like a conventional air-breathing jet engine. The engine would then transition to rocket power to propel the aircraft to space. On its return journey the aircraft could then transition back to jet power and land like a traditional jetliner on a conventional runway. The same engine could then be used again and again, dispensing with the waste of expendable rocket stages—even the expense of refurbishing reusable rocket stages like those envisioned by SpaceX.

The ideas underpinning Reaction’s Synergetic Air-Breathing Rocket Engine, or SABRE, were first developed more than three decades ago. But some fundamental technology hurdles—chief among them how to move enough heat out of the engine so that it won’t burn itself up—have kept the concept on paper up to this point. Among the critical technology breakthroughs Reaction engineers claim is a heat exchanger that can cool incoming air as hot as 1,800 degrees Fahrenheit to subzero temperatures in a fraction of a second, allowing the engine to function at higher speeds than traditional air-breathing jet engines.

“This could fundamentally change the way aerospace works,” says Chris Allam, engineering director for BAE’s aerospace business. If the technology works as designed, he says, it could spawn a new breed of aircraft engines capable of much higher speeds and performance.

And for BAE, it offers a critical toehold in the growing space access market. While BAE’s North American arm does a fair amount of business in satellite components and the like, the company has no significant presence in the commercial space launch industry. “It’s a market we’re interested in but we were looking for a different way of doing it,” Allam says. “We were looking for a breakthrough or something new as opposed to just joining everybody else.”

If BAE can help Reaction’s engineers make SABRE fly, it may prove to be the revolutionary propulsion breakthrough the company is looking for. Critically, the $32 million raised from BAE will also unlock an additional $90 million in grants from the UK government for research and development. As part of the deal, BAE will get a seat on Reaction’s board and become a preferred supplier to Reaction. The privately-held Reaction will also lean on BAE for support in mounting a large-scale aerospace testing and development program for the SABRE engine.

The companies plan to have a ground-based demonstrator engine prototyped and firing by 2020 and a further prototype flying on a test aircraft by 2025. If there are no show-stoppers along the way, a SABRE-powered spacecraft could propel itself to space and back by the end of the next decade.

And what about that super-high-speed point-to-point passenger travel—four hours from anywhere to anywhere on the globe? It’s certainly possible with this kind of technology, Reaction’s Thomas says. But given various safety and technical considerations, a spaceplane making regular trips to orbit at 25 times the speed of sound is the more realistic near-term proposition.

“A lot of people are excited about point-to-point travel at the moment, the thought of going anywhere in the world in four hours just excites people,” he says. “But that is hugely challenging, it’s just orders of magnitude more difficult. I was telling someone from Australia recently that, unfortunately, it’s more difficult to get to Australia than it is to get into space.”