2009年12月17日星期四

17-12-2009 Boeing Dreamliner 787 takes its maiden flight





By Dan Reed, USA TODAY

The future of commercial aviation arrived Tuesday — albeit 28 months late — when Boeing's 787 Dreamliner took off from Paine Field in Everett, Wash., just before 10:30 a.m. on its maiden flight.

The Dreamliner, whose test flight was repeatedly postponed, won't enter commercial service until late next year at the earliest. And that's only if everything goes perfectly during what promises to be the most rigorous flight-testing and certification program in commercial aviation history.

The Dreamliner is the first commercial aircraft to be made mostly from composites rather than conventional aluminum and steel.

Aviation analyst Richard Aboulafia, of The Teal Group, says certification should take at least 12 months. Then, he says, Boeing must get production volumes up and "improve the plane so that it comes close to being the plane that it was promised to be." That, he says, "may take them 200 or so planes to do."

Another analyst, Jon Ostrower, who has tracked the 787's star-crossed development, says the six delays that pushed back the Dreamliner's first flight more than two years did produce a benefit: more opportunity to work out bugs in advanced systems on the plane that flew Tuesday.

"Now this is when the hard part really begins," he says. "Boeing has the opportunity to take what was the symbol of their struggles — this plane sitting on the ground — and give it the chance to prove itself. It allows Boeing to start on the road back to restoring their credibility."
Befitting its nickname, the Dreamliner is arguably the most anticipated new commercial plane.
At one point, Boeing had nearly 940 orders for 787s. But the delays and tough economic conditions caused airlines to cancel at least 83 orders this year alone. At present, airlines have more than 840 firm orders in place for 787s.

Airlines desire the 787 because it promises to cut the cost of flying long-range routes by 15% to 20%. Reduced weight, advanced design and more efficient engines from General Electric and Rolls-Royce make those savings possible over long distances, where the fuel savings can add up.
Consumers also are expected to benefit from the 787's wider and taller fuselage and its advanced environmental control systems, which Boeing officials claim will make the 787 the world's most comfortable plane.

The 787 offers passengers the prospect of more overhead baggage space. And it will have larger windows than current jetliners because the structural integrity of its hull won't be compromised by larger windows, as would be the case on conventional metal planes. Boeing also has added a nifty creature comfort to the larger windows: electric shades that roll up or down at the touch of a button.

2009年10月1日星期四

Su-35BM 飞行小意外

图片是2009年8月22日周六在航展上苏-35飞行资料图。


在俄第九届国际航空航天展览会上,俄最新歼击机苏-35BM差点因降落事故而报销。

俄媒8月26日报道说,MAKS-2009航展上发生的事故仅仅是之前“俄罗斯勇士”飞行表演队在彩排时发生的飞机相撞事故,还有一个事故也差点发生。

俄最新歼击机苏-35BM在降落时向右倾斜,其机翼离跑道仅几厘米之差几乎触地。俄航空专家表示,在这样的速度下如果飞机机翼触地,其后果是下一秒飞机就会嘴“啃”地、侧翻然后四分五裂。

有参观者还误以为是俄新式战机在进行特技表演。照片清楚显示,飞机降落时发生倾斜,靠右侧起落架落地。

2009年9月30日星期三

国庆60周年阅兵空中梯队受阅过程详解


在国庆60周年阅兵中,空中梯队将飞越天安门广场,持续时间9分20秒。空中梯队如何完成受阅,新华社记者为您详解全过程。

在7个军用机场起降

受阅飞机分别从南苑等7个军用机场起降。如果遇到极端天气,空中梯队还在北京周边准备了若干备用机场。

阅兵空中基准航线106公里

这次阅兵,空中梯队基准航线为一条直线,东起河北螺山火车站,向西经纪各庄、通州、天安门至公主坟,共106公里。

不同方式加入基准航线

空中12个梯队依次进入基准航线,并排列成一条直线,由东至西飞越天安门广场。但由于受阅的15种机型分驻在不同机场,而且速度大小不一,因此各梯队飞机起飞的顺序、时间都经过了周密计算。

受阅时,直升机梯队由通州上空加入基准航线,其余各梯队分别由螺山火车站、纪各庄加入基准航线。

作为领队梯队长机的空警-2000将最先起飞。

由单一机型组成的梯队,如轰炸机、歼击轰炸机、歼击机、直升机和教练机梯队,各驻在同一机场,它们起飞后即编队飞行,按规定高度、时间在规定地点加入基准航线。

多机型的混合编队,如领队梯队、预警机梯队、加受油机梯队,不驻在同一机场,大飞机先飞至小飞机所在机场,等候小飞机起飞后编队,再按规定高度、时间在规定地点加入基准航线。

直升机梯队飞行高度低、速度慢、飞行距离近,加入基准航线后其他梯队要从直升机梯队上方超越。

梯队顺序体现空中作战体系

空中梯队大体按预警机、对地突击飞机、制空作战飞机、直升机、教练机的顺序排序,体现攻防兼备的空中作战体系。

通过位置点为人民英雄纪念碑上空

受阅时,空中梯队通过天安门广场的位置点为人民英雄纪念碑上空,距天安门城楼水平距离450米。

从第一架领队梯队长机——空警-2000通过人民英雄纪念碑上空,到最后1个梯队教8飞机通过人民英雄纪念碑上空,持续时间9分20秒。

各受阅梯队中,直升机梯队通过天安门广场时高度最低,为250米,其余梯队高度在250米至600米之间。

2个梯队拉烟通过天安门广场

受阅时,第一个通过天安门广场的领队梯队中的8架歼-7GB护卫机,将拉出彩色烟雾。最后一个通过天安门广场的教练机梯队的最后1个5机楔队,也将拉烟。

各梯队前后间隔一般40秒

受阅时,各梯队前后间隔一般40秒,最小20秒。梯队中的各编队间隔只有5秒。

空中梯队总长75公里。

大部分飞机间隔距离在15至20米

受阅时,大部分编队内飞机间隔距离在15至20米左右。

值得一提的是,在加受油梯队中,空军2架轰油-6将分别与空军2架歼-10、2架歼-8D组成2个加受油楔队,模拟空中加受油状态飞越天安门广场。它们之间的间隔距离是空中梯队中最小的——受油机距加油机加油锥套只有2米。

受阅要求:米秒不差

在通过人民英雄纪念碑上空时,空中梯队要求各编队队形的间隔距离误差在1米之内,到达时间与规定时间误差在1秒之内,这已超过了现行训练大纲的规定。

作战飞机挂弹受阅

这次阅兵中,空中梯队所有作战飞机都将挂弹受阅,多型空空、空地导弹首次公开亮相。

这将是空中梯队在历次国庆阅兵中第二次挂弹受阅,第一次是1949年的开国大典。

为了保证安全,空中梯队已拆除所有挂载导弹的战斗部和引信;没有接通导弹与飞机上的电源;挂弹飞机在飞行中一律关闭武器控制电门;采取特殊措施加固导弹与挂架的连接,防止飞行中导弹掉落。

空中梯队分别在复兴门、公主坟上空解散

飞越天安门广场上空后,直升机梯队在复兴门上空解散,其余各梯队在公主坟上空解散,返回各机场。

来源:新华网

第七代雷鸟照片

General Dynamics/Lockheed Martin F-16 Fighting Falcon 1982~Current





第六代雷鸟照片

Northrop T-38 Talon 1974-1981



第五代雷鸟照片

McDonnell-Douglas F-4E Phantom II 1969-1073





第四代雷鸟照片

Republic F-105 Thunderchief 1964



第三代雷鸟照片

North American F-100C Super Sabre 1956-1963


North American F-100D Super Sabre 1964-1968

第二代雷鸟照片

Republic F-84F Thunderstreak 1955



第一代雷鸟照片

Republic F-84G Thunderjet 1953-1954

Thunderbirds 雷鸟飞行表演队


美国空军---雷鸟飞行表演中队

“雷鸟”表演队全称“美国空军飞行表演中队”(USAF Demonstration Squadron),现驻内华达州内利斯空军基地,使用9架F-16C“战隼”战斗机和3架F-16D双座教练型,表演时采用6机编队。

“雷鸟”表演队于1953年5月25日在亚利桑那州卢克空军基地组建,仅两周后就开始表演,至今已半个世纪。“雷鸟”的命名部分是受卢克空军基地所在的美国西南部较浓厚的印第安文化影响,“雷鸟”据说是一种神鸟,当它腾空而起时,大地也会在它的巨翼扇起的雷鸣中颤抖,眼中还会发出闪电。

刚组建时,该表演队称为第3600飞行表演部队,共7名军官和22名士兵,主要来自卢克基地,首任队长迪克·卡特利奇少校。有趣的是,左右翼的僚机分别由一对双胞胎上尉担任。表演队的宗旨是作为“蓝天大使”,帮助空军征兵,向公众展示空军人员的职业化水平和当时刚刚出现的高性能喷气式飞机的力量,后一点并不只是为了表演,因为朝鲜战争中喷气式飞机才刚投入实战,需要让公众信任这种新技术。

该表演队装备的第一种喷气式飞机是共和航空公司的F-84G“雷电喷气”(Thunderjet),这种亚音速平直翼战斗轰炸机经历了朝鲜战争的实战检验。1955年初,“雷鸟”换装了后掠翼的F-84F“电闪”(Thunderstreak),并已经开始到中美洲和南美洲国家表演,还开始采用拉烟技术。在使用F-84的3年中,“雷鸟”就表演了222场,观众900万以上。

北美公司的F-100“超佩刀”是第一种超音速喷气战斗机,1956年成为“雷鸟”的第3种机型,这也使它成为世界上第一支使用超音速喷气战斗机的表演队。这一年该中队迁至现在的内利斯基地,编入第57联队。这一时期,虽然不属例行表演课目,“雷鸟”有时也应表演组织者的要求在单机表演时进行超音速飞行,但联邦航空机构很快禁止在任何航空表演中超音速飞行。

1964年,“雷鸟”还短暂地使用过F-105B“雷公”(Thunderchief)战斗机,只在4月26日到5月9日间进行了6场表演,就改为可以空中加油的F-100D。使用F-100的13年是令人难忘的,“雷鸟”共使用F-100C和D型表演1100场以上,并首次出现在远东、欧洲和北非的天空。

1969年,“雷鸟”换装了F-4E“鬼怪”II,这是越战时期的主力战斗机,也是第一种和唯一的一种被“雷鸟”和“蓝天使”同时采用的机型。F-4E是“雷鸟”最震撼的机型,四机编队的F-4E有8台J-79发动机,声如雷鸣。5年间,F-4E共表演500场以上,到过美国的30个州,以及加拿大、中美洲和欧洲。

但由于1974年石油危机来临,“雷鸟”改用了世界上第一种超音速喷气教练机——T-38A“禽爪”(Talon),该机省油(5架的耗油量才相当于一架F-4),维护成本低,一直使用了8年,表演近600场。在1976年美国建国200周年庆典中,该机型还为华盛顿特区的国家航空航天博物馆开馆仪式助兴。

1983年初,“雷鸟”换装了F-16A战斗机,又回到了使用前线战斗机的时代,换装的头一个表演季节,全美就有33个州的1650万观众目睹了美国最新战斗机技术的展示。1987年,“雷鸟”在进行远东巡回表演时,曾在中国北京的南苑机场进行了表演,这是美国的表演队首次出现在社会主义国家。

1992年又换成了F-16A的改进型F-16C,它是最后一个换装C型的F-16中队。1994年,“雷鸟”进入了第5个十年,这一年表演67场,观众600万,使累计观众总数超过了2.75亿。1996年,“雷鸟”首次出现在东欧国家,对罗马尼亚、斯洛文尼亚、保加利亚等9国进行了访问,回国后又参加了亚特兰大奥运会的开幕式。11月10日,“雷鸟”用F-16的飞行表演达到了1000场。

至今,“雷鸟”表演队已在美国50个州和世界60个国家表演,成为历史上周游世界各地最多的表演队,1999年累计观众就突破了3.15亿。

当前,“雷鸟”表演队隶属空军空战司令部,任务是:支援美国空军征兵,促进军人续签服役合同;增强空军全军的信心,向公众展示空军人员优良的职业素质;鼓舞空军士气和团队精神,改善空军团队关系;向外国展示美国及其武装力量的形象和良好意愿。

“雷鸟”全队共有8名飞行员(其中6名表演飞行员)、115名士兵、4名支援军官和4名文职人员,有27个不同岗位,一般包括10%-15%的女性,2003年有8人。军官在该中队服役时间为2年,士兵3-4年,每年更新近1/3的人员。飞行员至少要有1000小时军用喷气飞机驾驶经验,每年从申请人中选出4-5人面试,竞争3个名额,入选后要完成120架次训练飞行。地勤人员每年有4个新名额,训练需要21天。

在3500多场次正式空中表演中,“雷鸟”没有一次因为飞机机械故障而停止表演。最早的表演包括持续15分钟的一系列编队特技。起初,备份机会提前起飞,观察天气、周围空域有无越界飞行器和障碍等情况后降落,继续担任备份。后来这一机会被用作单机表演。早期的表演季节很短,1974年时只有4个月,这一年“雷鸟”共表演35场,今天的表演季节已经发展到从每年3月到11月,一共要表演88场,每次表演有30个机动动作,包括编队飞行和单机表演,整个表演从地面算起历时1小时15分钟。

“雷鸟”现有的F-16改动很小,只拆除了雷达、内置20毫米机炮和弹鼓,改装了发烟系统,油门杆上的格斗开关换成拉烟开关,并增加一个秒表。但表演专用设备不断改进,比如现在的拉烟器是向飞机喷管中喷入一种石蜡油,遇到高温喷流立即汽化,形成烟迹。

“雷鸟”的表演对天气要求较高,从表演中心看去水平能见度9.26千米,云底高至少457米时,也只能进行基本表演;云底高1067米时可进行一般表演,包括一些滚转机动;云底高2438米时才能进行全部动作的表演。

“雷鸟”平均每年在北美40个地点表演70场,表演季节内几乎每个周末都有表演。一般周四到达表演场地,前一天到达的先遣飞行员通报当地情况。周五一般是预演,熟悉地形地标,试飞后还要安排一些会见、参观等公关活动。周六正式表演,同时要安排一些入伍和续签合同仪式,媒体见面会等活动。在每个表演地,“雷鸟”还可以安排两名当地媒体的记者乘F-16D双座机进行体验飞行,每年还安排一些电视台和体育、音乐、电影界的人员体验飞行,目的是促进宣传报道,树立良好形象。

2009年7月29日星期三

Virgin Galactic Rolls Out Mother Ship



Virgin Group head Sir Richard Branson unveiled the latest addition to his air- and spaceline fleet at the Mojave Airport in California today, accompanied by the craft's chief designer, Burt Rutan.

The White Knight 2 is a four-engine jet that will carry an 8-seat spaceship called SpaceShipTwo to an altitude of 48,000 feet so that the spaceship can drop off and fire its rocket engine for a brief run to suborbital space. Branson's Virgin Galactic hopes to begin regularly scheduled passenger service to space in 2010.

Rutan's company Scaled Composites made history in 2004 with the world's first privately funded manned spaceflights by its three-seat SpaceShipOne, which was carried aloft by the original White Knight. The White Knight 2 features two fuselages, each with its own cabin, connected by a single continuous wing arching between them, where the spaceship will ride. With the wing span of a B-29 bomber, it is the largest all-carbon-fiber aircraft yet built.

On hand to christen the White Knight Two outside a Scaled hangar was Branson's mother, Eve. Not coincidentally, Eve is also the name of the mother ship. "If you're going to name a mother ship," Branson quipped to a gathering of perhaps two hundred reporters and dignitaries, including Apollo 11 moonwalker Buzz Aldrin, "you might as well name it after your own mother."

Eve Branson stood with her son beside the White Knight 2 as Sir Richard shook a bottle of Champagne and then hosed down a gaggle of reporters photographing the event as he opened it. When asked how she felt having an exotic new aircraft named after her, Eve replied, "I don't know what to say. But am I allowed to drink this?"

Kidding aside, Branson has serious aspirations for the White Knight 2. Besides carrying paying passengers to space, 270 of whom have ponied up $200,000 each for tickets or put down substantial deposits, Branson envisions White Knight 2 ferrying government, industrial, and academic researchers and their experiments into the realm of weightless flight on a regular basis. Future craft using the White Knight 2/SpaceShipTwo technology could also enable superfast travel from one point on the Earth to another.

The White Knight 2 will begin ground testing tomorrow, with flight testing expected to begin in the fall. SpaceShipTwo is still under construction, with flight testing pending the conclusion of an investigation into the causes of a test stand explosion that claimed the lives of three Scaled employees last summer.

Virgin Galactic president Will Whitehorn said today that the spaceship would not fly passengers until it was absolutely safe to do so. "Safety is our north star," he said. "Safety is crucial to us because Virgin is invested in four airlines, including Virgin America, in four continents.... Our name has become a byword for safety and innovative and efficient transportation solutions."

That's a hard-won reputation the hugely profitable group of companies won't willingly squander.

2009年7月22日星期三

Senate votes to stop production of F-22 jet


WASHINGTON (Reuters) – The U.S. Senate voted on Tuesday to stop production of the F-22 fighter plane, handing President Barack Obama a victory as he tries to rein in defense spending.
The Senate voted 58 to 40 to strip $1.75 billion for the Lockheed Martin Corp-built planes from a $680 billion defense bill, overriding the objections of lawmakers seeking to protect manufacturing jobs in the midst of a deep recession.

The Senate's vote does not necessarily kill the program, as the House of Representatives included funding for the state-of-the-art fighter in its bill, which sets military spending priorities.
The two chambers must resolve their differences before sending a final bill to the president to sign into law.

Obama has threatened a veto if Congress continues to fund the F-22 beyond the 187 planes already built or in the production pipeline.

"At a time when we're fighting two wars and facing a serious deficit, this would have been an inexcusable waste of money," Obama said after the vote.

Defense Secretary Robert Gates has proposed capping production as part of an overhaul of the Pentagon's weapons programs as it tries to provide resources to fight insurgencies like those in Iraq and Afghanistan. The Pentagon applauded the vote.

Later on Tuesday the Senate voted 93-1 to extend the authorized end strength of the U.S. Army by 30,000 troops over the next three years starting October 1.

The amendment, by Sen. Joseph Lieberman, does not mandate the increase, but provides the authority for Defense Secretary Robert Gates to carry out his plan for a temporary increase of 22,000 in the Army's size and go further if he needs to, a Senate staffer said. The House has passed similar language.

In a separate voice vote, the Senate also adopted a measure that urges Obama to impose sanctions on Iran's central bank if that country continues to pursue its nuclear program and rejects an offer for diplomatic talks.

The radar-evading F-22 is designed for combat against other fighter jets but has not seen action in the Iraq or Afghanistan conflicts, where U.S. foes have not fielded an air force. Critics point out that each hour of flight time requires 30 hours of maintenance and say the plane is a relic of Cold War military strategy.

The Pentagon wants instead to ramp up production of the cheaper, more versatile F-35 Joint Strike Fighter, and Gates said last week that funding for that program could be jeopardized if Congress continues to fund the F-22.

Lockheed Martin is the primary contractor for both planes. The company's stock closed at $75.13, down 8.5 percent, on a day when it posted better-than-expected quarterly earnings but failed to raise its full-year forecast.

F-22 backers in the Senate said national security could be compromised if the plane was canceled. Up to 95,000 jobs across the country also could be at risk, said Democratic Senator Chris Dodd of Connecticut, a hub of defense manufacturing.

"To give up an aircraft of this sophistication and this capability, and simultaneously in an economic situation such as we're in .... I think is terribly shortsighted," Dodd said.

Republican Senator John McCain said it was more important to rein in unnecessary spending at a time when the country is amassing a record $1.8 trillion budget deficit.

McCain, Obama's rival in the 2008 presidential contest, said the president deserved credit for "being very firm on this issue" and described the vote as a "big victory for the American taxpayer."

The overall defense authorization bill includes $550.4 billion for military operations and $130 billion for the wars in Afghanistan and Iraq for the fiscal year starting October 1.
The bill has become a vehicle for several provisions unrelated to military spending, such as the Iran amendment.

Last week, the Senate approved a measure that would expand hate-crime protection to gays and lesbians, and on Monday also extended that protection to military members.
On Wednesday, the Senate is scheduled to consider a provision that would make it easier for gun owners to carry concealed weapons across state lines.

The House version includes $369 million in advanced procurement funds as a down payment on 12 more F-22 jets in fiscal 2011.

A final vote on the Senate bill could come later this week, but the two chambers might not begin to hammer out their differences until September.

2009年7月1日星期三

What Supersonic Looks Like


A U.S. Air Force F-22 Raptor executes a supersonic flyby over the flight deck of the aircraft carrier USS John C. Stennis (CVN 74) in the Gulf of Alaska, in this handout photo taken on June 22, 2009. The John C. Stennis is participating in Northern Edge 2009, a joint exercise focusing on detecting and tracking units at sea, in the air and on land. Picture taken on June 22, 2009.

2009年6月29日星期一

2009年6月28日星期日

HB-SIA solar-powered aircraft






The HB-SIA solar-powered aircraft, the first prototype of the Solar Impulse project, is to be unveiled next week on June 26 at Dübendorf air base, near Zurich, Switzerland. Those who attend will discover some design changes since the last images were released, company CEO André Borschberg told AIN, adding that a first flight is planned for later this year.

In February, Solar Impulse engineers were elated when the main spar successfully completed load tests, which simulated situations such as a combination of turbulence and extreme piloting maneuvers. The trials involved flexion and torsion of the aircraft’s 200-foot-long spar. The spar was fixed at its center and lead weights were gradually added onto approximately 30 platforms suspended by cables or winches distributed along its span. They were loaded in four stages–25, 50, 75 and 100 percent–yielding a total load equivalent to 3.5gs. With the total load–comprising 5.5 metric tons of lead–the deflection measured at the wing tips was almost four feet.

Ten people worked eight months to manufacture the spar, which underwent 60 thermal treatments to meet resistance and weight goals.

Two months earlier, in December, the spar underwent vibration testing aimed at assessing the risk of resonance. The tests defined the aircraft’s natural frequencies and checked the correspondence between the model calculated by the engineers and its real technical characteristics.

Using electrodynamic devices fixed at different points on the airframe, German aerospace research agency (DLR) experts caused the aircraft to vibrate. They measured the repercussions with 71 sensors placed along the spar, the fuselage, the tailboom and the engine and battery supports. In all, they tested around 100 vibration modes at frequencies varying from 8 to 20 Hz.

The test results revealed a few minimal differences with the computer model that the engineers had developed. The elasticity modulus for the structure turned out to be slightly lower than planned, which was good news because the aircraft is more flexible than they anticipated.

The Solar Impulse defies normal aircraft conventions: “It is the size of an Airbus, has the weight of a car and runs on the power of a scooter,” Borschberg quipped.

The aircraft weighs just 3,300 pounds. Its batteries are charged by 2,150 sq ft of photovoltaic cells affixed to the wing. The photovoltaic cells–which are composed of single-crystal silicon with a 180-micron thickness–are at the forefront of solar technology. They are said to offer 22 percent efficiency.

The wing also carries four 10-hp electric motors, and over a 24-hour period, the Solar Impulse’s average speed is projected to be close to 38 knots.

Of course, building a solar aircraft makes sense only if it can also fly at night. Energy accumulated during the day will be stored in two ways. One way is electric, via the HB-SIA’s batteries which have an energetic density of 225 Wh per kilogram. The second way is potential energy: the pilot will have the aircraft climbing during daytime, and at night, this will allow the aircraft to lose altitude while keeping to the preset flight profile.

HB-SIA is the first of two aircraft planned to be built. It is scheduled to perform full 36-hour flight cycles, hopefully this year. However, as Borschberg’s team has set its sights on an around-the-world flight (including stopovers), it needs a bigger airplane, which it will build with lessons learned from the HB-SIA. Plans are for a flight across the Atlantic in 2011.

The Solar Impulse’s project initiator is Bertrand Piccard, who flew nonstop around the world in a balloon 10 years ago. Piccard and Borschberg are to be the HB-SIA’s pilots. Both already have performed long-duration simulated flights on the ground in the aircraft’s single-seat cockpit.

In the past, solar technology pioneers flew unmanned aircraft at night using the electricity produced onboard during the day; others flew several hundred miles in one day. None of them, however, combined manned flight with long duration.

Solar Impulse partners include, among others, aircraft manufacturer Dassault, the International Air Transport Association (IATA), engineer consultancy firm Altran, chemical and materials specialist Solvay, watchmaker Omega, the Ecole Polytechnique Fédérale de Lausanne (EPFL) and Deutsche Bank.

2009年5月14日星期四

Paragliding

Paragliding is a recreational and competitive flying sport. A paraglider is a free-flying, foot-launched aircraft. The pilot sits in a harness suspended below a fabric wing, whose shape is formed by its suspension lines and the pressure of air entering vents in the front of the wing.

History

In 1952 Domina Jalbert advance governable parachutes with multi-cells and controls for controlling lateral glide of the device.

In 1954, Walter Neumark predicted (in an article in Flight magazine) a time when a glider pilot would be “able to launch himself by running over the edge of a cliff or down a slope ... whether on a rock-climbing holiday in Skye or ski-ing in the Alps”.

In 1961, the French engineer Pierre Lemoigne produced improved parachute designs which led to the Para-Commander (‘PC’), which had cut-outs at the rear and sides that enabled it to be towed into the air and steered – leading to parasailing/parascending.

Sometimes credited with the greatest development in parachutes since Leonardo da Vinci, the American Domina Jalbert invented his filed-for January 10, 1963 US Patent 3131894 the Parafoil which had sectioned cells in an aerofoil shape; an open leading edge and a closed trailing edge, inflated by passage through the air – the ram-air design.

Meanwhile, David Barish was developing the Sail Wing for recovery of NASA space capsules – “slope soaring was a way of testing out ... the Sail Wing”.After tests on Hunter Mountain, New York in September 1965, he went on to promote ‘slope soaring’ as a summer activity for ski resorts (apparently without great success).NASA originated the term ‘paraglider’ in the early 1960s, and ‘paragliding’ was first used in the early 1970s to describe foot-launching of gliding parachutes.

Author Walter Neumark wrote Operating Procedures for Ascending Parachutes, and he and a group of enthusiasts with a passion for tow-launching ‘PCs’ and ram-air parachutes eventually broke away from the British Parachute Association to form the British Association of Parascending Clubs (BAPC) in 1973. Authors Patrick Gilligan (Canada) and Betrand Dubuis (Switzerland) wrote the first flight manual "The Paragliding Manual" in 1985, officially coining the word Paragliding.

These threads were pulled together in June 1978 by three friends Jean-Claude Bétemps, André Bohn and Gérard Bosson from Mieussy Haute-Savoie, France. After inspiration from an article on ‘slope soaring’ in the Parachute Manual magazine by parachutist & publisher Dan Poynter, they calculated that on a suitable slope, a ‘square’ ram-air parachute could be inflated by running down the slope; Bétemps launched from Pointe du Pertuiset, Mieussy, and flew 100 m. Bohn followed him and glided down to the football pitch in the valley 1000 metres below. ‘Parapente’ (pente being French for slope) was born.

From the 1980s equipment has continued to improve and the number of paragliding pilots has continued to increase. The first World Championship was held in Kössen, Austria in 1989.

Equipment

Wing

The paraglider wing or canopy is known in aeronautical engineering as a ram-air airfoil, or parafoil. Such wings comprise two layers of fabric which are connected to internal supporting material in such a way as to form a row of cells. By leaving most of the cells open only at the leading edge, incoming air (ram-air pressure) keeps the wing inflated, thus maintaining its shape. When inflated, the wing's cross-section has the typical teardrop aerofoil shape.

Note: In some modern paragliders (from the 90's onwards), especially higher performance wings, some of the cells of the leading edge are closed to form a cleaner aerodynamic airfoil. Like the wingtips, these cells are kept inflated by the internal pressure of the wing.The pilot is supported underneath the wing by a network of lines. The lines are gathered into two sets as left and right risers. The risers collect the lines in rows from front to back in either 3 or 4 rows, distributing load as in a whippletree. The risers are connected to the pilot's harness by two carabiners.

Paraglider wings typically have an area of 20-35 m2 with a span of 8–12 m, and weigh 3–7 kg. Combined weight of wing, harness, reserve, instruments, helmet, etc. is around 12–18 kg.

The glide ratio of paragliders ranges from 8:1 for recreational wings, to about 11:1 for modern competition models[citation needed]. For comparison, a typical skydiving parachute will achieve about 3:1 glide. A hang glider will achieve about 15:1 glide. An idling (gliding) Cessna 152 will achieve 9:1. Some sailplanes can achieve a glide ratio of up to 72:1.

The speed range of paragliders is typically 20–60 km/h (12-34 mph), from stall speed to maximum speed. Beginner wings will be in the lower part of this range, high-performance wings in the upper part of the range. The range for safe flying will be somewhat smaller.

Modern paraglider wings are made of high-performance non-porous fabrics such as Skytex (Porcher Sport) & Gelvenor, with Dyneema/Spectra or Kevlar/Aramid lines.

For storage and carrying, the wing is usually folded into a rucksack (bag), which can then be stowed in a large backpack along with the harness.

For pilots who may not want the added weight or fuss of a backpack, the harness itself can be used to carry the wing, though this is less comfortable, and thus less favorable for longer hikes. In this case the wing (within the rucksack) is buckled into the harness seat, which is then slung over the shoulders. Recent developments in light-weight harness design include the ability to turn the harness inside out such that it becomes the backpack, thus removing the need for a second storage system.

Tandem paragliders, designed to carry the pilot and one passenger, are larger but otherwise similar. They usually fly faster with higher trim speeds, are more resistant to collapse, and have a slightly higher sink rate compared to solo paragliders.

Since 2000 Juan Salvadori from Argentina has been exploring a variant wing termed Paramontante that involves some firm beams. In April 2009 Pere Casellas has joined in a collaboration with Juan Salvadori for polishing the paramontante. Laboratori d'envol Paramontante

Harness

The pilot is loosely and comfortably buckled into a harness which offers support in both the standing and sitting positions. Modern harnesses are designed to be as comfortable as a lounge chair in the sitting position. Many harnesses even have an adjustable 'lumbar support'.

A reserve parachute is also typically connected to a paragliding harness.

Parachutes, including skydiving canopies, primary design purpose is for descending, such as jumping out of an aircraft or for dropping cargo; while paragliders design purpose is for ascending.

Paragliders are categorized as "ascending parachutes" by canopy manufacturers worldwide, and are designed for "free flying" meaning flight without a tether (for tethered flight amusement, see parasailing).However, in areas without high launch points, paragliders may be towed aloft by a ground vehicle or a stationary winch, after which they are released, creating much the same effect as a mountain launch.

Such tethered launches can give a paraglider pilot a higher starting point than many mountains do, offering similar opportunity to catch thermals and to remain airborne by "thermaling" and other forms of lift.As free flight, paragliding requires the significant skill and training required for aircraft control, including aeronautical theory, meteorological knowledge and forecasting, personal/emotional safety considerations, adherence to applicable Federal Aviation Regulations (US), and knowledge of equipment care and maintenance.

Instruments

Most pilots use variometers, radios, and, increasingly, GPS units when flying.

Variometer

Birds are highly sensitive to atmospheric pressure, and can tell when they are in rising or sinking air. People can sense the acceleration when they first hit a thermal, but cannot detect the difference between constant rising air and constant sinking air, so turn to technology to help. Modern variometers are capable of detecting rates of climb or sink of 1 cm per second, such is the case of the Flymaster B1 which uses extremely low noise electronics and complex algorithms to detect such minute changes in air pressure.

A variometer indicates climb-rate (or sink-rate) with audio signals (beeps which increase in pitch and tempo as you accelerate upwards and a droning sound which gets deeper as your descent rate increases) and/or a visual display. It also shows altitude: either above takeoff, above sea level, or (at higher altitudes) "flight level".The main purpose of a variometer is in helping a pilot find and stay in the "core" of a thermal to maximise height gain, and conversely indicating when he or she is in sinking air, and needs to find rising air.

The more advanced variometers have an integrated GPS. This is not only more convenient, but also allows to record the flight in three dimensions. The track of the flight is digitally signed, stored and can be downloaded after the landing. Digitally signed tracks can be used as proof for record claims, replacing the 'old' method of photo documentation.

Radio

Pilots use radio for training purposes, for communicating with other pilots in the air, particularly when travelling together on cross-country flights, and for reporting the location of landing.

Radios used are PTT (push-to-talk) transceivers, normally operating in or around the FM VHF 2-metre band (144–148 MHz) , often without the correct licence, and causing interference problems with legitimate users for many miles around. Usually a microphone is incorporated in the helmet, and the PTT switch is either fixed to the outside of the helmet, or strapped to a finger.

GPS

GPS (global positioning system) is a necessary accessory when flying competitions, where it has to be demonstrated that way-points have been correctly passed.It can also be interesting to view a GPS track of a flight when back on the ground, to analyze flying technique. Computer software is available which allows various different analyses of GPS tracks.

Other uses include being able to determine drift due to the prevailing wind when flying at altitude, providing position information to allow restricted airspace to be avoided, and identifying one’s location for retrieval teams after landing-out in unfamiliar territory.

More recently, the use of GPS data, linked to a computer, has enabled pilots to share 3D tracks of their flights on Google Earth. This fascinating insight allows comparisons between competing pilots to be made in a detailed 'post-flight' analysis.

Control

Brakes: Controls held in each of the pilot’s hands connect to the trailing edge of the left and right sides of the wing. These controls are called 'brakes' and provide the primary and most general means of control in a paraglider. The brakes are used to adjust speed, to steer (in addition to weight-shift), and flare (during landing).

Weight Shift: In addition to manipulating the brakes, a paraglider pilot must also lean in order to steer properly. Such 'weight-shifting' can also be used for more limited steering when brake use is unavailable, such as when under 'big ears' (see below). More advanced control techniques may also involve weight-shifting.

Speed Bar: A kind of foot control called the 'speed bar' (also 'accelerator') attaches to the paragliding harness and connects to the leading edge of the paraglider wing, usually through a system of at least two pulleys (see animation in margin). This control is used to increase speed, and does so by decreasing the wing's angle of attack. This control is necessary because the brakes can only slow the wing from what is called 'trim speed' (no brakes applied). The accelerator is needed to go faster than this.

More advanced means of control can be obtained by manipulating the paraglider's risers or lines directly:

Most commonly, the lines connecting to the outermost points of the wing's leading edge can be used to induce the wingtips to fold under. The technique, known as 'big ears', is used to increase rate of descent (see picture).

The risers connecting to the rear of the wing can also be manipulated for steering if the brakes have been severed or are otherwise unavailable.

In a 'B-line stall', the second set of risers from the leading-edge/front is gently pulled down to put a crease across the lower surface of the wing (this will also distort the upper surface) acting as an 'air brake' significantly reducing airspeed. The combination of reduced forward airspeed and increased vertical airspeed destroys the laminar flow of air over the aerofoil, dramatically reducing the lift produced by the canopy, thus inducing a higher rate of descent.

Fast Descents

Problems with “getting down” can occur when the lift situation is very good or when the weather changes unexpectedly. There are three possibilities of rapidly reducing altitude in such situations.

Spiral Dive

The spiral dive is the most effective form of fast descent: With a little bit of practice you will achieve a sink rate of 15 m/s and more. It is absolutely necessary that you gradually approach these values the first few times! Constant pulling on one brake narrows the radius of the turn and forms a spiral rotation in which high sink rates can be reached. As soon as the glider is in a spiral dive (clear increase of sink rate and turn bank), the outside wing should always be stabilised with the outside brake and the desired sink rate should be controlled with great delicacy.

B-Line-Stall

Out of unaccelerated normal flight, it is best to grasp the B-lines on both sides above the line links and pull them down. There is no need to release the toggles while B-stalling. Then a full stall will occur, the canopy bunches up in the direction of the profile and by pulling down further you will achieve a high sink rate while keeping a completely stable “flight” position. Pulling the B-lines even further down will not enhance the sink rate but lead to a more unstable flight position and turning away of the canopy. By releasing the risers the canopy will accelerate immediately without strong oscillation effects. Should it not catch up right away, a simultaneous push on the A-risers will remedy this condition.

Big Ears

By pulling on the rear (outer) A-riser and holding down the outer A-lines the wing tips of the glider can be folded in. This method drastically deteriorates the glide angle without necessarily affecting forward speed. The effectiveness of this technique can be increased by using the speed system at the same time. To reinflate on a low performance glider (e.g. DHV1 rated) it is simply necessary to release the lines.On higher performance gliders (e.g. DHV1/2 and above) it may be necessary to help the reinflation with brief, deep pumps of the brakes. Whilst big ears are in use, the loading on the glider is increased and it is therefore more stable and less prone to collapse. However the stall speed is raised and so the pilot must be very cautious about applying brake (it is best not to).

Flying

Launching

As with all aircraft, launching and landing are done into wind (though in mountain flying, it is possible to launch in nil wind and glide out to the first thermal).

Forward launch

In low winds, the wing is inflated with a ‘forward launch’, where the pilot runs forward so that the air pressure generated by the forward movement inflates the wing.

Reverse launch

In higher winds, particularly ridge soaring, a ‘reverse launch’ is used, with the pilot facing the wing to bring it up into a flying position, then turning under the wing to complete the launch.Reverse launches have a number of advantages over a forward launch. It is more straight forward to inspect the wing and check the lines are free as it leaves the ground. In the presence of wind, the pilot can be tugged toward the wing and facing the wing makes it easier to resist this force, and safer in case the pilot slips (as opposed to being dragged backwards).

These launches are normally attempted with a reasonable wind speed making the ground speed required to pressurise the wing much lower - the pilot is initially launching while walking forwards as opposed to running backward.

Towed launch

In flatter countryside pilots can also be launched with a tow. Once at full height, the pilot pulls a release cord and the towline falls away. This requires separate training, as flying on a winch has quite different characteristics from free flying.There are two major ways to tow: Pay-in and pay-out towing. Pay-in towing involves a stationary winch that pays in the towline and thereby pulls the pilot in the air. The distance between winch and pilot at the start is around 500 meters or more. Pay-out towing involves a moving object, like a car or a boat, that pays out line slower than the speed of the object thereby pulling the pilot up in the air. In both cases it is very important to have a gauge indicating daN to avoid pulling the pilot out of the air.There is one other form of towing; ‘static’ towing. This involves a moving object, like a car or a boat, attached to a paraglider or hanglider with a fixed length line. This is very dangerous because now the forces on the line have to be controlled by the moving object itself, which is almost impossible to do. With static line towing a lockout is bound to happen sooner or later. Static line towing is forbidden in most countries and if not, should be avoided at all cost.

Landing

Landing involves lining up for an approach into wind, and just before touching down, ‘flaring’ the wing to minimise vertical speed.

In light winds, some minor running is common. In moderate to medium headwinds, the landings can be without forward speed.

Ridge soaring

In ridge soaring, pilots fly along the length of a ridge feature in the landscape, relying on the lift provided by the air which is forced up as it passes over the ridge.

Ridge soaring is highly dependent on a steady wind within a defined range (the suitable range depends on the performance of the wing and the skill of the pilot). Too little wind, and insufficient lift is available to stay airborne (pilots end up ‘scratching’ along the slope). With more wind, gliders can fly well above and forward of the ridge, but too much wind, and there is a risk of being ‘blown back’ over the ridge.

Thermal flying

When the sun warms the ground, it will warm some features more than others (such as rock-faces or large buildings), and these set off thermals which rise through the air. Sometimes these may be a simple rising column of air; more often, they are blown sideways in the wind, and will break off from the source, with a new thermal forming later.

Once a pilot finds a thermal, he or she begins to fly in a circle, trying to center the circle on the strongest part of the thermal (the "core"), where the air is rising the fastest. Most pilots use a ‘vario’ (vario-altimeter), which indicates climb rate with beeps and/or a visual display, to help ‘core-in’ on a thermal.

Coring: The technique to "core" a thermal is simple: turn tighter as lift decreases, and turn less as lift increases. This ensures you are always flying around the core.

Often there is strong sink surrounding thermals, and there is often also strong turbulence resulting in wing collapses as a pilot tries to enter a strong thermal. Once inside a thermal, shear forces reduce somewhat and the lift tends to become smoother.

Good thermal flying is a skill which takes time to learn, but a good pilot can often "core" a thermal all the way to cloud base.

Cross-country flying

Once the skills of using thermals to gain altitude have been mastered, pilots can glide from one thermal to the next to go ‘cross-country’ (‘XC’). Having gained altitude in a thermal, a pilot glides down to the next available thermal.Potential thermals can be identified by land features which typically generate thermals, or by cumulus clouds which mark the top of a rising column of warm, humid air as it reaches the dew point and condenses to form a cloud. In many flying areas, cross-country pilots also need an intimate familiarity with air law, flying regulations, aviation maps indicating restricted airspace, etc.

In-flight Wing Deflation (Collapse)

Since the shape of the wing (airfoil) is formed by the moving air entering and inflating the wing, in turbulent air part or all of the wing (airfoil) can deflate (collapse). Piloting techniques referred to as "active flying" will greatly reduce the frequency and severity of deflations or collapses. On modern recreational wings, such deflations will normally recover themselves without pilot intervention.In the event of a severe deflation, correct pilot input will speed recovery from a deflation, but incorrect pilot input may slow the return of the glider to normal flight, so pilot training and practice in correct response to deflations is necessary.

For the rare case where it is not possible to recover from a deflation (or from other threatening situations such as a spin), most pilots carry a reserve (rescue, emergency) parachute.Most pilots never have cause to ‘throw’ their reserve. In case the wing deflation happens near ground, i.e. shortly after takeoff or just before landing, the wing (paraglider) may not recover (airfoil shape) even with pilot intervention and there may not be enough time for successful rescue parachute deployment.

Those cases can result in serious bodily injury or death. In-flight wing deflation and other hazards are minimized by flying a suitable glider, and choosing appropriate weather conditions and locations, for the pilot's skill and experience level.

Safety

Paragliding is perhaps often viewed as a higher-risk sport than it actually is. Nonetheless, there is great potential for injury for the reckless or ill-prepared.

The safety of the sport is directly proportional to the skill and sense of the pilot. It's important to note that almost all paragliding accidents are the result of pilot error. Paragliding equipment is very well built and, if properly cared for, will never fail.As an example, the average paraglider has around 30 lines connected to the risers, yet each one is strong enough to support the full weight of a pilot individually. Aerodynamically, newer paragliders that are not within advanced or competition categories are rated for safety and will tend to recover from most incidents on their own (without pilot intervention).

Given that equipment failure of properly certified paragliding equipment can be considered a non-issue, it is accurate to say that paragliding can be a very safe sport. The individual pilot is the ultimate indicator of his or her personal safety level.

In general:

The safe pilot will not fly at sites that pose an unreasonable challenge to his/her flying skills.

The safe pilot will not be influenced by the possibly negative examples set by others.

The safe pilot will only fly on days in which the weather is conducive to safe flight. Turbulence in all its forms is enemy #1 for a flying paraglider wing. Because paragliders have no solid support, their shape (and ability to fly) can be ruined by an errant down draft or the like. Therefore, turbulence or conditions conducive to turbulence generation is a primary factor in determining whether the weather is safe.

The following weather is to be avoided:

Excessive wind speed or gustiness. 15mph wind is fairly windy for a paraglider, and most pilots won't take off in much more wind than that. High winds will also increase the effect of mechanical turbulence. Gusty conditions will make take-offs and landings more dangerous and will make collapses more likely while in flight.

A wind direction that will not allow a take-off (or landing) into the wind, or at least generally so. Tail-wind take-offs are to be avoided at all cost. Assurance that an [apparent] headwind is not actually a 'rotor' is also critical (rotors comprise a form of mechanical turbulence).

Excessively high atmospheric instability, indicated in part by overdeveloped cumulus clouds, or in worse situations by cumulo-nimbus cloud formation. Such conditions will contribute to turbulence. If cumulo-nimbus (thunderstorm) clouds are anywhere in sight, the effect of severe atmospheric instability may exist where you are.

Rain or snow. Because a paraglider wing is made from fabric, it has the ability to absorb moisture. Moreover, the weight (or lack thereof) of a paraglider wing is critical to its performance. Flying into heavy rain or snow will weigh the wing down and may terminate a flight quickly. A wet wing is also less controllable, less stable (more prone to collapse) and will exhibit less tendency to recover into normal flight.

General safety precautions include pre-flight checks, helmets, harnesses with back protection (foam or air-bag), reserve parachutes, and careful pre-launch observation of other pilots in the air to evaluate conditions.

For pilots who want to stretch themselves into more challenging conditions, advanced ‘SIV’ (simulation d’incidents en vol, or simulation of flying incidents) courses are available to teach pilots how to cope with hazardous situations which can arise in flight.Through instruction over radio (above a lake), pilots deliberately induce major collapses, stalls, spins, etc, in order to learn procedures for recovering from them. (As mentioned above, modern recreational wings will recover from minor collapses without intervention).

As always, fatalities and freak accidents can occur, but most properly-trained, responsible pilots risk only minor injuries, such as twisted ankles.

Learning to fly

Most popular paragliding regions have a number of schools, generally registered with and/or organized by national associations. Certification systems vary widely between countries, though around 10 days instruction to basic certification is standard.

There are several key components to a paragliding pilot certification instruction program. Initial training for beginning pilots usually begins with some amount of ground school to discuss the basics, including elementary theories of flight as well as basic structure and operation of the paraglider.

Students then learn how to control the glider on the ground, practicing take-offs and controlling the wing 'overhead'. Low, gentle hills are next where students get their first short flights, flying at very low altitudes, to get used to the handling of the wing over varied terrain. Special winches can be used to tow the glider to low altitude in areas that have no hills readily available.

As their skills progress, students move on to steeper/higher hills (or higher winch tows), making longer flights, and learning to turn the glider, control the glider's speed, then moving on to 360° turns, spot landings, ‘big ears’ (used to increase the rate of descent for the paraglider), and other more advanced techniques. Training instructions are often provided to the student via radio, particularly during the first flights.

A third key component to a complete paragliding instructional program provides substantial background in the key areas of meteorology, aviation law, and general flight area etiquette.

To give prospective pilots a chance to determine if they would like to proceed with a full pilot training program, most schools offer tandem flights, in which an experienced instructor pilots the paraglider with the prospective pilot as a passenger. Schools often offer pilot's families and friends the opportunity to fly tandem, and sometimes sell tandem pleasure flights at holiday resorts.

Most recognised courses lead to a national licence and an internationally recognised International Pilot Proficiency Information/Identification card. The IPPI specifies five stages of paragliding proficiency, from the entry level ParaPro 1 to the most advance stage 5.

World records

FAI (Fédération Aéronautique Internationale) world records:

Straight distance – 461.6 km: Frank Brown, Marcelo Prieto, Rafael Monteiro Saladini (Brazil); Quixada – Duque, Brazil; 14 November 2007.

Straight distance to declared goal – 368.9 km: Aljaž Valič, Urban Valič (Slovenia); Vosburg – Jamestown (South Africa); 7 December 2006

Gain of height – 4526 m: Robbie Whittall (UK); Brandvlei (South Africa); 6 January 1993

Other records (distance/speed for out-and-return and triangular course) can be seen on the FAI site

Recently a flight of over 500 km was made in excellent conditions in South Africa; however this is awaiting full ratification.

Pilot numbers

Numbers of actively flying pilots can only be a rough estimate, but France is believed to have the largest number, at around 25,000. Next most active flying countries are Germany, Austria, Switzerland, Japan, and Korea, at around 10,000 – 20,000, followed by Italy, the UK, and Spain with around 5,000 – 10,000. The USA has around 4,500. (All as of 2004).

2009年5月2日星期六

什么是飞行伞?


什么是飞行伞?  
飞行伞是一种双足起降、以充气软翼为主体的飞行器。其飞行动力是风力、重力和飞行员的操纵力。  

飞行伞的组成部分?  
飞行伞由伞体、伞绳、操纵带和鞍具组成。另外,还有刹车绳,用来控制飞行的速度和方向,挂钩,用来连接伞绳和鞍具。分述如次:  

(1) 伞体:是由上层、下层、和隔间(气室)组成的。材质为30丹尼的强力尼龙布。  
(2) 伞绳:可分为ABCDE共五组。材质为防弹纤维内芯,外敷尼龙。  
(3) 操纵带:是将各组的伞绳相连接的组合带,依设计性能而有所不同。一般有ABCD四组。  (4) 鞍具:即套带。分为肩带、胸带与腿带。胸带有H型及交叉型。为了保护飞行者的脊髓,通常类套带的下方与背部装有海绵或防弹纤维板、玻璃纤维板、气囊等保护装置。另外,在肩带前方各有一个挂钩,用来连接伞体与飞行员。  

飞行伞和降落伞是一回事儿吗?  
不是一回事儿。飞行伞有点象一个现代化的、可以操纵的空中滑行降落伞,但它与降落伞有几点重要的不同之处:  
(1) 结构:飞行伞是一种起降设备,因此没有DROUGE伞或滑件,其构造也更为轻盈(因为它不需要承担高速降落中猛然打开时的冲力)。飞行伞的伞衣气室较多,伞绳也较细。  
(2) 起飞方式:飞行伞一定要由一个有落差的山坡上逆风起飞,借着向前跑的速度及风吹的速度,产生將伞翼往上提的『升力』后,便会将人帶离地面。而高空跳伞必須要有航空载具,如:飞机、热气球等。  
(3) 开伞程序:飞行伞在起飞前,已將伞衣打开铺在地面。高空跳伞是跳离载具后,经过一段自由落体(或立刻)将伞衣由伞包中拉出。  
(4) 飞行性能:飞行伞可盘旋、滑翔、爬升、越野、滞空。 高空伞仅能下降。
(5)外观:飞行伞的翼展较长,形狀接近梭形。高空伞为长方形, 且上方多一个小小的引导伞,在跳伞员的头顶上有一块方形的減震布,用來減轻伞翼张开时的震动。  

飞行伞与滑翔翼有什么区别?  
(1) 滑翔翼有一个刚性框架,能保持翼体的三角形的形状。飞行伞的伞衣则靠空气压力维持其梭形、橢圓形、橄欖形的形状。  
(2) 滑翔翼的的空气动力学结构较为明朗,其飞行速度比飞行伞要快得多。  
(3) 滑翔翼的飞行员一般悬挂在翼体下方俯式飞行,其身体外包着一个象虫蛹似的吊袋。飞行伞的飞行员一般是坐在一个椅子式的鞍具上(有时为仰式),胸前有两根吊袋与伞衣连接。  
(4) 操纵方式:滑翔翼是利用身体的重心移动来操纵:前推-加速;后拉-减速;左移 -左转;右移-右转。飞行伞则是利用两条操纵绳,拉左手-左转;拉右手-右转;拉双手-减速。  

一具伞能用多久?  
在使用中,飞行伞会因为磨损、拉扯(这是主要因素)和风吹日晒等多种因素而老化。其使用寿命一般在4年左右,当然这同使用条件和使用频度有着相当密切的关系。  

在空中飞行时应遵守什么交通规则?  
空中飞行并不象很多人认为的那样是无拘无束,“天高任我飞”。由于在同一空域往往有多架飞行器同时飞行,所以我们也必须象在地面开车时一样,遵守特定的交通规划,以避免意外发生。一般规则如下:  
(1) 速度快的要让速度慢的。  
(2) 有动力的要让无动力的。  
(3) 同向時,高度高的要让高度低的。  
(4) 同向又同高度時,右边的先行。  
(5) 两方相遇时各向右转。  
(6) 超越時应由右方超越。  
(7) 进入热气流盘旋时,以先进入气流者的方向为方向。  
(8) 右侧靠山壁者可直行。  
(9) 不要到当地航空管制部门指定的空域范围之外飞行,以免误闯军事敏感区、国家安全敏感区、边境管理区等。

2009年5月1日星期五

Reaching for a Record


Reaching for a RecordThe Waverider, a.k.a. the X-5, is illustrated here in flight. The experimental aircraft is designed to fly more than six times faster than the speed of sound on ordinary jet fuel

April 29, 2009 -- Hoping to bridge the gap between airplanes and rocketships, the U.S. military is preparing to test an experimental aircraft that can fly more than six times faster than the speed of sound on ordinary jet fuel.

Officially, it's known as the X-51, but folks like to call it the WaveRider because it stays airborne, in part, with lift generated by the shock waves of its own flight. The design stems from the goal of the program -- to demonstrate an air-breathing, hypersonic, combustion ramjet engine, known as a scramjet.

"We built a vehicle around an engine," said Joseph Vogel, the X-51 project manager with Boeing, which is building a series of four test planes under a $246.5-million program managed by the Air Force Research Laboratory in Dayton, Ohio.

2009年4月20日星期一

Cockpit Voice Recorders

Cockpit Voice Recorders

In almost every commercial aircraft, there are several microphones built into the cockpit to track the conversations of the flight crew. These microphones are also designed to track any ambient noise in the cockpit, such as switches being thrown or any knocks or thuds. There may be up to four microphones in the plane's cockpit, each connected to the cockpit voice recorder (CVR).

Any sounds in the cockpit are picked up by these microphones and sent to the CVR, where the recordings are digitized and stored. There is also another device in the cockpit, called the associated control unit, that provides pre-amplification for audio going to the CVR. Here are the positions of the four microphones:

Pilot's headset
Co-pilot's headset
Headset of a third crew member (if there is a third crew member)
Near the center of the cockpit, where it can pick up audio alerts and other sounds

Most magnetic-tape CVRs store the last 30 minutes of sound. They use a continuous loop of tape that completes a cycle every 30 minutes. As new material is recorded, the oldest material is replaced. CVRs that used solid-state storage can record two hours of audio. Similar to the magnetic-tape recorders, solid-state recorders also record over old material.

How Black Boxes Work



Flight Data Recorders

The flight data recorder (FDR) is designed to record the operating data from the plane's systems. There are sensors that are wired from various areas on the plane to the flight-data acquisition unit, which is wired to the FDR. When a switch is turned on or off, that operation is recorded by the FDR.

In the United States, the Federal Aviation Administration (FAA) requires that commercial airlines record a minimum of 11 to 29 parameters, depending on the size of the aircraft. Magnetic-tape recorders have the potential to record up to 100 parameters. Solid-state FDRs can record more than 700 parameters. On July 17, 1997, the FAA issued a Code of Federal Regulations that requires the recording of at least 88 parameters on aircraft manufactured after August 19, 2002.

Here are a few of the parameters recorded by most FDRs:

Time
Pressure altitude
Airspeed
Vertical acceleration
Magnetic heading
Control-column position
Rudder-pedal position
Control-wheel position
Horizontal stabilizer
Fuel flow

Solid-state recorders can track more parameters than magnetic tape because they allow for a faster data flow. Solid-state FDRs can store up to 25 hours of flight data. Each additional parameter that is recorded by the FDR gives investigators one more clue about the cause of an accident.

Built to Survive
In many airline accidents, the only devices that survive are the crash-survivable memory units (CSMUs) of the flight data recorders and cockpit voice recorders. Typically, the rest of the recorders' chassis and inner components are mangled. The CSMU is a large cylinder that bolts onto the flat portion of the recorder. This device is engineered to withstand extreme heat, violent crashes and tons of pressure. In older magnetic-tape recorders, the CSMU is inside a rectangular box.

Using three layers of materials, the CSMU in a solid-state black box insulates and protects the stack of memory boards that store the digitized information. We will talk more about the memory and electronics in the next section. Here's a closer look at the materials that provide a barrier for the memory boards, starting at the innermost barrier and working our way outward:

Aluminum housing - There is a thin layer of aluminum around the stack of memory cards.

High-temperature insulation - This dry-silica material is 1 inch (2.54 cm) thick and provides high-temperature thermal protection. This is what keeps the memory boards safe during post-accident fires.

Stainless-steel shell- The high-temperature insulation material is contained within a stainless-steel cast shell that is about 0.25 inches (0.64 cm) thick. Titanium can be used to create this outer armor as well.
Testing a CSMU

To ensure the quality and survivability of black boxes, manufacturers thoroughly test the CSMUs. Remember, only the CSMU has to survive a crash -- if accident investigators have that, they can retrieve the information they need. In order to test the unit, engineers load data onto the memory boards inside the CSMU. L-3 Communications uses a random pattern to put data onto every memory board. This pattern is reviewed on readout to determine if any of the data has been damaged by crash impact, fires or pressure.

There are several tests that make up the crash-survival sequence:

Crash impact - Researchers shoot the CSMU down an air cannon to create an impact of 3,400 Gs (1 G is the force of Earth's gravity, which determines how much something weighs). At 3,400 Gs, the CSMU hits an aluminum, honeycomb target at a force equal to 3,400 times its weight. This impact force is equal to or in excess of what a recorder might experience in an actual crash.

Pin drop - To test the unit's penetration resistance, researchers drop a 500-pound (227-kg) weight with a 0.25-inch steel pin protruding from the bottom onto the CSMU from a height of 10 feet (3 m). This pin, with 500-pounds behind it, impacts the CSMU cylinder's most vulnerable axis.

Static crush - For five minutes, researchers apply 5,000 pounds per square-inch (psi) of crush force to each of the unit's six major axis points.

Fire test - Researchers place the unit into a propane-source fireball, cooking it using three burners. The unit sits inside the fire at 2,000 degrees Fahrenheit (1,100 C) for one hour. The FAA requires that all solid-state recorders be able to survive at least one hour at this temperature.

Deep-sea submersion - The CSMU is placed into a pressurized tank of salt water for 24 hours.

Salt-water submersion - The CSMU must survive in a salt water tank for 30 days.

Fluid immersion - Various CSMU components are placed into a variety of aviation fluids, including jet fuel, lubricants and fire-extinguisher chemicals.
During the fire test, the memory interface cable that attaches the memory boards to the circuit board is burned away. After the unit cools down, researchers take it apart and pull the memory module out. They restack the memory boards, install a new memory interface cable and attach the unit to a readout system to verify that all of the preloaded data is accounted for.

Black boxes are usually sold directly to and installed by the airplane manufacturers. Both black boxes are installed in the tail of the plane -- putting them in the back of the aircraft increases their chances of survival. The precise location of the recorders depends on the individual plane. Sometimes they are located in the ceiling of the galley, in the aft cargo hold or in the tail cone that covers the rear of the aircraft.

"Typically, the tail of the aircraft is the last portion of the aircraft to impact," Doran said. "The whole front portion of the airplane provides a crush zone, which assists in the deceleration of tail components, including the recorders, and enhances the likelihood that the crash-protected memory of the recorder will survive."

Solid-state Technology

Solid-state recorders are considered much more reliable than their magnetic-tape counterparts, according to Ron Crotty, a spokesperson for Honeywell, a black-box manufacturer. Solid state uses stacked arrays of memory chips, so they don't have moving parts. With no moving parts, there are fewer maintenance issues and a decreased chance of something breaking during a crash.

Data from both the CVR and FDR is stored on stacked memory boards inside the crash-survivable memory unit (CSMU). In recorders made by L-3 Communications, the CSMU is a cylindrical compartment on the recorder. The stacked memory boards are about 1.75 inches (4.45 cm) in diameter and 1 inch (2.54 cm) tall.

The memory boards have enough digital storage space to accommodate two hours of audio data for CVRs and 25 hours of flight data for FDRs.

Airplanes are equipped with sensors that gather data. There are sensors that detect acceleration, airspeed, altitude, flap settings, outside temperature, cabin temperature and pressure, engine performance and more. Magnetic-tape recorders can track about 100 parameters, while solid-state recorders can track more than 700 in larger aircraft.

All of the data collected by the airplane's sensors is sent to the flight-data acquisition unit (FDAU) at the front of the aircraft. This device often is found in the electronic equipment bay under the cockpit. The flight-data acquisition unit is the middle manager of the entire data-recording process. It takes the information from the sensors and sends it on to the black boxes.

Both black boxes are powered by one of two power generators that draw their power from the plane's engines. One generator is a 28-volt DC power source, and the other is a 115-volt, 400-hertz (Hz) AC power source. These are standard aircraft power supplies, according to Frank Doran, director of engineering for L-3 Communications Aviation Recorders.