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近日，超音速飛行的相關(guān)研究文件已經(jīng)在不知不覺間堆滿了各個(gè)工程研究工作站的桌面，靜待美國宇航局(NASA)的審閱，從而選出一種最好的初步方案，以設(shè)計(jì)低音爆超音速飛行演示機(jī)。據(jù)了解，美國宇航局在2017財(cái)年預(yù)算中加入了一項(xiàng)名為新航空地平線(New Aviation Horizons)的倡議，計(jì)劃推出了一系列X-plane機(jī)型，這駕超音速演示機(jī)就是其中的第一架。

“美國航空航天局正在努力提升飛機(jī)的飛行速度，同時(shí)讓飛機(jī)更環(huán)保、更安全、更安靜，并且還在構(gòu)建一個(gè)運(yùn)行更加高效的航空系統(tǒng)。”美國宇航局局長Charles Bolden日前表示，“值得注意的是，如今距離美國王牌飛行員Chuck Yeager駕駛一架貝爾X-1(Bell X-1)試驗(yàn)機(jī)首次沖破音障(sound barrier)，已經(jīng)過去了近70年。現(xiàn)在，我們將延續(xù)超音速X-plane的傳奇，推出一架更加安靜的超音速噴氣式客運(yùn)飛機(jī)。”

為了實(shí)現(xiàn)這一目標(biāo)，美國宇航局精心挑選了一組由洛克希德·馬丁航空公司(Lockheed Martin Aeronauics)帶領(lǐng)的研發(fā)團(tuán)隊(duì)，完成靜音超音速運(yùn)輸(QueSST)系統(tǒng)的初步設(shè)計(jì)。這項(xiàng)工作將在美國宇航局位于弗吉尼亞州的蘭利研究中心(Langley Research Center)進(jìn)行，屬于該中心的基礎(chǔ)與應(yīng)用航空航天研究技術(shù)項(xiàng)目(Basic and Applied Aerospace Research and Technology)。

在真正推出商業(yè)化超音速飛機(jī)之前，美國宇航局進(jìn)行了一系列靈活性研究，從而更好地了解全美各地對(duì)飛行噪聲的接受程度。然后，宇航局要求航空業(yè)提交能夠?qū)崿F(xiàn)超音速飛行的試驗(yàn)機(jī)設(shè)計(jì)概念，但這種飛機(jī)必須滿足宇航局提出的“超音速心跳”噪聲控制要求，也就是說新的超音速飛機(jī)的噪聲不能超過“心跳般”的輕輕撞擊聲，而不能像過去那樣轟轟作響，震得房屋窗戶也會(huì)跟著晃動(dòng)。

洛克希德·馬丁公司將在未來超過17個(gè)月內(nèi)獲得約2000萬美金的經(jīng)費(fèi)，進(jìn)行QueSST項(xiàng)目的初步設(shè)計(jì)。GE航空集團(tuán)(GE Aviation)和Tri Models公司也是團(tuán)隊(duì)成員，將負(fù)責(zé)按照規(guī)格開發(fā)基礎(chǔ)飛機(jī)需求、完成初步飛機(jī)設(shè)計(jì)，并提供有關(guān)概念成型與規(guī)劃的配套文檔。這些文檔將用于準(zhǔn)備QueSST噴氣機(jī)的詳細(xì)設(shè)計(jì)、實(shí)際建造和后續(xù)測試。此外，初步設(shè)計(jì)的飛機(jī)性能也必須經(jīng)過分析驗(yàn)證和風(fēng)洞測試驗(yàn)證。

洛克希德公司并不是最近才開始進(jìn)行超音速飛行研究，幾年前該公司就曾服務(wù)于美國宇航局的N+2項(xiàng)目。洛克希德·馬丁公司N+2項(xiàng)目經(jīng)理Micheal Buonanno表示，那時(shí)我們并不是僅“開發(fā)了一個(gè)全新的推進(jìn)系統(tǒng)”，而且還探索了多種新技術(shù)的應(yīng)用，包括“低噪聲飛機(jī)排氣系統(tǒng)、集成風(fēng)扇噪聲抑制系統(tǒng)、機(jī)體噪聲抑制系統(tǒng)，以及計(jì)算機(jī)定制機(jī)場噪聲消減系統(tǒng)。”

正是由于Buonanno的團(tuán)隊(duì)“成功開發(fā)了一套工具和代碼，如今工程師和設(shè)計(jì)師才能準(zhǔn)確地預(yù)測飛機(jī)的音爆水平。”

該項(xiàng)目在初期的低音爆飛行演示(Low Boom Flight Demonstration)階段，還將驗(yàn)證社區(qū)將對(duì)這種更加安靜的超音速設(shè)計(jì)作何反應(yīng)。未來，QueSST飛機(jī)的詳細(xì)設(shè)計(jì)與建造將通過合同競標(biāo)方式，選擇最合適的公司完成。

美國宇航局的“新航空地平線項(xiàng)目”為期10年，主要圍繞在通過與傳統(tǒng)飛機(jī)“機(jī)身加機(jī)翼(tube-and-wing)”形態(tài)不同的創(chuàng)新飛機(jī)設(shè)計(jì)，減少燃料使用、實(shí)現(xiàn)減排目標(biāo)，并降低飛機(jī)噪聲。該項(xiàng)目打造的X-plane通常僅有量產(chǎn)機(jī)型一半的尺寸，很有可能可以駕駛。據(jù)了解，飛機(jī)的設(shè)計(jì)與建造工作將花費(fèi)數(shù)年時(shí)間，可能將于2020年左右開始進(jìn)行飛行活動(dòng)，具體時(shí)間將主要取決于經(jīng)費(fèi)情況。

作者：Jean L. Broge
來源：SAE《航空航天工程》雜志
翻譯：SAE 上海辦公室

NASA takes a respectable-sized step toward supersonic flight

Research on supersonic flight has quietly been infiltrating the desks of a variety of engineering work stations, verified by NASA's recent contract award for the preliminary design of a flight demonstration aircraft with a low boom profile. This is the first in a series of X-planes in NASA's New Aviation Horizons initiative, introduced in the agency’s Fiscal Year 2017 budget.

“NASA is working hard to make flight greener, safer, and quieter—all while developing aircraft that travel faster, and building an aviation system that operates more efficiently,”  NASA Administrator Charles Bolden said recently. “It’s worth noting that it's been almost 70 years since Chuck Yeager broke the sound barrier in the Bell X-1. Now we’re continuing that supersonic X-plane legacy with this preliminary design award for a quieter supersonic jet with an aim toward passenger flight."

To that end, NASA selected a team led by Lockheed Martin Aeronautics to complete a preliminary design for Quiet Supersonic Technology (QueSST). The work will be conducted under a task order against the Basic and Applied Aerospace Research and Technology (BAART) contract at NASA's Langley Research Center in Virginia.

Prior to going out to industry, NASA conducted feasibility studies to better understand acceptable sound levels across the country. It then asked industry teams to submit design concepts for a piloted test aircraft that can fly at supersonic speeds, creating what it describes as a "supersonic heartbeat"—a soft thump rather than the window-shaking boom most often associated with supersonic flight.

Lockheed Martin will receive about $20 million over 17 months for QueSST preliminary design work. GE Aviation and Tri Models are also part of the team, which will develop baseline aircraft requirements and a preliminary aircraft design, with specifications, and provide supporting documentation for concept formulation and planning. This documentation will be used to prepare for the detailed design, building, and testing of the QueSST jet. Performance of the preliminary design also must undergo analytical and wind tunnel validation.

Lockheed is  not a newcomer to the study of supersonic flight, having worked on the NASA N+2 program some years ago. In that concept not only was a "totally new kind of propulsion system developed," but the company also explored "new techniques for low noise jet exhaust, integrated fan noise suppression, airframe noise suppression, and computer customized airport noise abatement," according to Micheal Buonanno, Lockheed Martin's Manager of that N+2 program.

It was his team that developed the "tools and codes that allow engineers and designers to accurately predict the loudness of a plane's sonic boom."

This initial Low Boom Flight Demonstration phase of the project also will include validation of community response to the new, quieter supersonic design. The detailed design and building of the QueSST aircraft will fall under a future contract competition.

NASA’s 10-year New Aviation Horizons initiative is built around reducing fuel use, emissions, and noise through innovations in aircraft design that departs from the conventional tube-and-wing aircraft shape. The X-planes that come out of the initiative will typically be about half-scale of a production aircraft and likely are to be piloted. Design-and-build will take several years with aircraft starting their flight campaign around 2020, depending on funding.

Author: Jean L. Broge
Source: SAE Aerospace Engineering Magazine