鐵之狂傲

 取回密碼
 註冊
搜尋

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

X-33 VentureStar
The Reusable Launch Vehicle (RLV) Technology Program is a partnership between NASA and industry to design a new generation of launch vehicles expected to dramatically lower the costs of putting payloads in space. Today's launch systems are complex and costly to operate. The RLV program stresses a simple, fully reusable vehicle that will operate much like an airliner. NASA hopes to cut payload costs from $10,000 a pound, as it is today, to about $1,000 a pound. To accomplish this goal, NASA sought proposals from US aerospace industries for the RLV Technology Program.

On August 5, 1994, President Clinton issued the National Space Transportation Policy and designated NASA as the Lead Agency for advanced technology development and demonstration of the next generation of RLVs. Three concepts and preliminary designs were prepared independently by: (1) Lockheed Martin Skunk Works, Palmdale, California; (2) McDonnell-Douglas Aerospace, Huntington Beach, California; and (3) Rockwell International Corporation, Space Systems Division, Downey, California.
>In July 1996, NASA selected Lockheed Martin Skunk Works of Palmdale CA to design, build and test the X-33 experimental vehicle for the RLV program. The selected team consists of Lockheed-Martin (lead by the Skunk Works in Palmdale, CA), Rocketdyne (Engines), Rohr (Thermal Protection Systems), Allied Signal (Subsystems), and Sverdrup (Ground Support Equipment), and various NASA and DoD laboratories. NASA has budgeted $941 million for the X-33 program through 1999. Lockheed Martin will invest at least $212 million in its X-33 design.
 

回覆 使用道具 檢舉

全世界最先進的跳動筆

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

Specific technology objectives of the X-33 space vehicle include:


demonstrate a reusable cryogenic tank system, including the tanks for liquid hydrogen (LH2) and liquid oxygen (LOX), cryogenic insulation, and an integrated thermal protection system (TPS)
verify TPS durability, low maintenance, and performance at both low and high temperatures
demonstrate guidance, navigation, and control systems, including autonomous flight control of checkout, takeoff, ascent, flight, reentry, and landing for an autonomously controlled space vehicle
achieve hypersonic flight speeds (speeds up to Mach 15 or 18,000 km/hr(11,000 mph))
demonstrate composite primary space vehicle structures integrated with the TPS
demonstrate ability to perform 7-day turnarounds between three consecutive flights (a turnaround is the amount of time required from a takeoff and flight until the vehicle is serviced, refueled, and ready to fly again)
demonstrate ability to perform a 2-day turnaround between two consecutive flights
demonstrate that a maximum of 50 personnel performing hands-on vehicle operations, maintenance, and refueling can successfully accomplish flight readiness for two flights.
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

Specific test flight objectives would include demonstration of:


successful interaction of the engines, airframe, and launch (also referred to as takeoff) facility
engine performance, thrust, and throttling capability meets specifications
operability and control of the X-33's flight control surfaces (canted fins, flaps, ailerons, etc.)
durability of the metallic thermal protection system during repeated flights
performance of the guidance, navigation, and control system
performance of primary operations facilities, including takeoff infrastructure
automated landing at a designated point on the runway
verification of tasks required to service the vehicle on landing and prepare it for next flight in minimal time.
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

The reusable, wedge-shaped X-33, called VentureStar, will be about half the size of a full-scale RLV. The X-33 will not take payloads into space; it will be used only to demonstrate the vehicle's design and simulate flight characteristics of the full-scale RLV. Lockheed Martin plans to conduct the first flight test in March 1999 and achieve at least 15 flights by December 1999. NASA has budgeted $941 million for the project through 1999. Lockheed Martin will invest $220 million in its X-33 design. After the test program, government and industry will decide whether or not to continue with a full-scale RLV.

The RLV will fly much like the Space Shuttle. It will take off vertically and land on a runway. However, there are differences between the two vehicles. The RLV will be a means of transport only. It will not be used as a science platform like the current Space Shuttle.

Also, the RLV will be a single-stage-to-orbit spacecraft it does not drop off components on its way to orbit. It will rely totally on its own built-in engines to reach orbit, omitting the need for additional boosters. Unlike the shuttle, the RLV will use a new linear aerospike engine, which looks and runs much differently than the bell-shaped Space Shuttle Main Engine. NASA considered the aerospike engine for the Space Shuttle 25 years ago, but opted to use the Space Shuttle Main Engine, also built by Rocketdyne. The aerospike has been revived and enhanced to power the RLV. The aerospike nozzle is shaped like an inverted bell nozzle. Where a bell nozzle begins small and widens toward the opening of the nozzle like a cone, the aerospike decreases in width toward the opening of the nozzle. The aerospike is 75 percent shorter than an equivalent bell nozzle engine. It is also lighter, and its form blends well with the RLV's lifting body airframe for lower drag during flight. The shape spreads thrust loads evenly at the base of the vehicle, causing less structural weight.

The half-scale X-33 test vehicle will use two smaller test versions of the aerospike, whilet the full-scale RLV will use seven aerospike engines. The X-33 main propulsion system (full system of engines and propellant tanks) consists of two J-2S aerospike engines, one aluminum LOX tank in the front, and two LH2 tanks in the rear for short- and mid-range flights. The vehicle could sustain one engine out at liftoff and still have sufficient power from the remaining engine to continue acceleration and make a safe landing at the intended runway or an abort landing area depending on where the engine out occurred during flight. For the long- range flights an engine out situation could be tolerated approximately 30 seconds after liftoff.
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

The X-33 was scheduled to complete its first flight by March of 1999. As of early 1999 the projected date for the X-33 rollout was May 1999, with its first flight planned for that July. The program is scheduled to be completed by the year 2000. The baseline test program would include a combined total of approximately 15 flights beginning in July 1999 and concluding in December 1999. The baseline test flight plan includes three short-range, seven mid-range, and five long-range test flights. Actual numbers of test flights to any range may vary due to changing plans and/or actual test flight data evaluation.

Test flights involve: (1) launching the X-33 from a vertical position like a conventional space launch vehicle閠his reduces the weight of the landing gear and wheels to only that required to support an unfueled vehicle (baseline dry weight of vehicle is approximately 29,500 kg (65,000 lb) and fueled weight of X-33 is approximately 123,800 kg (273,000 lb)); (2) accelerating the vehicle to top speeds of Mach 15 (15 times the speed of sound or approximately 18,000 km/hr (11,000 mph) and reaching high altitudes up to approximately 75,800 m (250,000 ft); (3) shutting down the engines; gliding over long distances up to 1,530 km (950 mi) downrange of the launch site followed by conducting terminal area energy maneuvers to reduce speed and altitude; and (4) landing like a conventional airplane.

Optimally, the flight test plan to meet Program objectives would involve flights of approximately 160, 720, or 1,530 km (100, 450, and 950 mi). Landing sites meeting the above criteria and providing 3,050 m (10,000 ft) of hard surface are referred to as short-, mid-, and long-range landing sites, respectively. The X-33 Program prefers to land the vehicle on a dry lake bed at least for its first flight in order to have a wider and slightly safer landing area than conventional runways offer. The same philosophy was used for the Orbiter's and most X-planes' first landings.
The launch site is located within Edwards Air Force Base, California. A total of fifteen launches are scheduled over a period of approximately one year. The X-33 will blast off from the site near Haystack Butte, located at the eastern edge of the Base near the AFRL/PR. Predominantly local NASA and USAF tracking and command assets will be utilized to support this phase of flight. Construction of the X-33 launch site at was completed in December 1998, just a little more than 12 months after groundbreaking.


Once the X-33 is readied for flight, the engines will be fired two times on the launch pad, with the second firing having a duration of 20 seconds. The longest flight will be approximately 20 minutes at an altitude of about 55 miles. The plan is to demonstrate a 2-day turnaround for the vehicle. Landing sites include Silurian Dry Lake Bed, Michael Army Air Field and Malmstrom Air Force Base. One of NASA's 747s will be used to carry the X-33 from its landing destinations back to Edwards.

Silurian Dry Lake Bed near Baker, California is approximately 3000 feet wide and 12000 feet long. The lake bed will be the site of the first landing attempts for the X-33 vehicle. Three flights are scheduled to Silurian Lake that will include vehicle speeds in excess of Mach 3. The flights are scheduled to start in mid 1999.

Michael Army Airfield will be the second landing site for the X-33. This will also be the first downrange runway landing. Michael Army Airfield is part of the Utah Test and Training Range, located south of Salt Lake City. This airfield is located on the eastern boundary of Dugway. The airfield has a 3,960 m (13,000 ft) long by 61 m (200 ft) wide hard surfaced runway. Immediate surrounding terrain is relatively flat. It is a secure facility with a long history of flight operations. The airspace above Dugway Proving Ground is restricted military airspace controlled by Hill Air Force Base which manages and approves use of the Utah Test and Training Range (UTTR). Seven flights are scheduled to Michael with vehicle speeds in excess of Mach 10. Flights are scheduled to start in the latter part of 1999.
Malmstrom Air Force Base will be the third and final landing site for the X-33. The airfield was closed on Decmeber 31, 1996, except for the area used by helicopters of the Malmstrom's Air Rescue Flight. The airfield has a hard surface runway approximately 3,500 m (11,500 ft) long and 61 m (200 ft) wide with a 305 m (1,000 ft) overrun at each end. Since closure of the airfield, the USAF has no plans or budget to operate the runway. Five flights are scheduled to the Malmstrom runway with vehicle speeds in excess of Mach 15. Flights are scheduled to start in the spring of 2000.
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

(文章來自:太空計劃)
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

X-33


X-33是美國太空總署的太空飛機之中最昂貴及最有抱負的。它是一個典型的單節式太空往返機。與其他航天工具不同,X-33的形狀是楔形的。

X-33的闊度比長度還要長,這設計的目的是使X-33能夠裝載全部需要的推進燃料,固態火箭推進燃料便可被消除了。發射X-33的成本大約是發射太空穿梭機的成本的十分之一。


X-33會以兩個特別設計的引擎推進。它是第一個使用Linear Aerospike引擎的太空飛機,因為這引擎的形狀會更適合X-33的形狀。 Aerospike噴氣口是V型的,與一般的火箭引擎的噴氣口不同,熱氣沿著噴氣口表面的孔噴出。

X-33計劃的最終目標是製造一個可代替太空穿梭機,名為VentureStar的商用太空飛機。 VentureStar的尺寸大約是X-33典型的兩倍,而Venture亦會使用同樣種類引擎及建築物料。 VentureStar不單可運悚貨物至太空,亦可被用作太空旅遊的飛行器。 X-33的成?與失敗決定了VentureStar能否成為公眾前往太空的飛行器。


以下是X-33的資料
長度 - 21米 (69呎)
闊度 - 23.5米 (77呎)
速度(使用Linear Aerospike引擎時) - 每小時14,645公里 (每小時9,100哩)
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

冒險之星
維基百科,自由的百科全書

冒險之星(VentureStar)是1996年美國洛克希德馬汀公司以單級入軌(SSTO)[1]、可再用的發射型運輸工具(RLV)[2]等理念所提出的一項設計提案,這項提案計畫的主要目標是開發出一種可再用(即重複使用)的無人式太空飛機,並運用此種飛機將人造衛星順利發射到原先設定的軌道上,根據估算此種新式的人造衛星發射法其發射成本將只有現今太空梭發射法的十分之一,倘若此新方式成功可行日後冒險之星將可用來取代太空梭。
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

三種往返任務

雖然「冒險之星」的主要目的是開發出一種無人駕駛的人造衛星發射器,但除此之外也被賦予其他的附屬、選用性用途,即是充當可運載乘客的客機,且主要是跨洲、洲際性的遠程飛行,也因為「冒險之星」採行無人駕駛設計,所以乘客將與人造衛星一樣,被「冒險之星」視為一種被運載的貨物。更簡單地說,「冒險之星」被期望成為可快速往返太空的低成本發射器,並且兼具模組化的運載系統設計,所被運載的可以是人造衛星也可以是乘客,甚至也被賦予日後往返於地球與太空站之間,為太空站運載必須的物資用品。
 

回覆 使用道具 檢舉

版主

S.I.A.M 管理者

Rank: 3Rank: 3Rank: 3

新隔熱技術、新推進技術

「冒險之星」不僅在用途與構想上具有相當的革新性,在實現技術上也相似,「冒險之星」預計將使用一種新式、金屬材質的隔熱技術(或稱:熱防護系統,thermal protection system),此一新隔熱技術與現有太空梭上所用的(陶瓷材質)隔熱技術相比,除了安全性更高外在維護成本上也更加低廉。

此外「冒險之星」為了成為單級入軌的運載器,在往返程序上是採行垂直發射升空之後再以類似飛航機的方式降落,對此「冒險之星」在設計上使用了一種新式的推進技術,稱為線性氣尖引擎(Linear Aerospike Engine,簡稱:LAE),此種新推進引擎無論在各種海拔高度都能提供高效率的推力。

附帶一提的是,「冒險之星」也試圖能有商業性的運用,期望能成為美國國家航空暨太空總署(NASA)所需求的航班性飛行。
 

回覆 使用道具 檢舉

你需要登入後才可以回覆 登入 | 註冊

存檔|手機版|聯絡我們|新聞提供|鐵之狂傲

GMT+8, 24-3-29 16:17 , Processed in 0.057277 second(s), 15 queries .

回頂部