FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1988
1988 - 0090.PDF
"Commercial use has been used to justify Ariane 5", says Gerry Webb of Commer cial Space Technologies, "but a 20-tonne payload is an embarrassment. One of the main problems is that it is unlikely that such large capacity can be filled optimally with commercial payloads. Because of this, apparent advantages in terms of cost per kilogramme to orbit can soon be eroded. It would seem a mandatory requirement to size Ariane 5 as a heavylift complement to such vehicles, rather than pay lip service to the idea of a commercial expendable 20-tonne triple launcher." For comparison, the Commercial Titan places 14 tonnes into low Earth orbit, the Proton 21 tonnes, and the Titan 4 CELV 17-6 tonnes. The Titan 4 can place a maximum of 5 • 4 tonnes into GTO, while the Proton and Titan 4 can place 2-2 tonnes and 4-5 tonnes directly into geostationary orbit (GEO). Not everyone agrees that there is no market for a larger GTO launcher, but with competition from Titan, Atlas Centaur, Delta II, Long March, and Proton, is there a large enough market for them all? The market is changeable, too, as the history of Ariane illustrates. The first Ariane was born of the pro jected need in 1973 to launch 1,600kg into GTO. It became clear before it flew, however, that this need had changed to the launch of two satellites weighing a total of 2,560kg into GTO. Thus Ariane 3 was born. Ariane 4 continues the policy, aiming with the most powerful of its six versions to place a total of 4,200kg into GTO, mostly in dual-satellite launches. This illustrates the changing face of the market, to which the versatile Ariane 2-4 system could adapt readily, but in which Ariane 5 has not, apparently, been afforded such a luxury. Ariane 3 and 4 lead the scoreboard in customer contracts, but this position could be undermined in the medium term by such market changes, says M. Vedrenne of Esa, in a report published at the IAF. "Three factors are paramount in the minds of launch customers today, in light of recent accidents: reliability, loss of income after a failure, and launch costs. Future users are going to choose which ever launch system is the most econo mical", says Vedrenne. To meet this commercial requirement, Ariane must be able to place into GTO one or more satellites with a total mass of 6,800kg, including the adapter or multiple-launch devices. This equates to a dual launch of 5,900kg into GTO. In addition to being what some observ ers describe as too big for the commercial market, Ariane 5 must also be able to place into 550km circular orbit at 28-5° Colum bus modules such as the Man Tended Free Flier, weighing 18,000kg, or to carry a 12,000kg polar platform to a height of 800km. It has to carry the 21-tonne Hermes spaceplane into a transfer orbit so that its own engine can place it in a final 500km orbit at 28-5°. Ariane 5 has to accommo date cylindrical payloads of as much as 4 • 57m in diameter. Its reliability target is 0-98 for the launcher's total missions, which results in a predicted reliability of 0 • 99 for the manned flights. It has to allow for the safe fallback of stages, and crew safety must not be compromised. The intrinsic safety target for Ariane-Hermes is 10-3. "Man-rating a commercial vehicle is an unnecessary requirement", says Webb. Ariane 5 should provide a reduction of Responsibility for industrial integration of Ariane 5 rests with Aerospatiale, but components are built all over Europe Industrial architect Aerospatiale (France) Vehicle equipment bay - Prime contractor: Matra (France) Fairing Prime contractor: Contraves (Switzerland) P230- — Stage developer: Aerospatiale (France) Boosters: Europropulston (France—Italy) Ground facilities Prime contractors: CNES (France) HM60teststand Prime contractors: SEP — DFVLR (France — Germany) SPELTRA Prime contractor: Dornier (Germany) -IS Stage developer: MBB— Erno (Germany) H155 Stage developer: Aerospatiale (France) HM60 vulcain Prime contractor: SEP (France) Speltra Fairing Attitude control blocks L5 20kN engine — P230 separation rockets P230 attachment P230 solid booster Venting holes Access door separation system Vehicle equipment bay Antennas Separation system H155fwd skirt P230 nose cone ; recovery module" H155 oxygen tank H155 hydrogen tank P230 nozzle Aft skirt Thrust cone HM60 Vulcain 36 FLIGHT INTERNATIONAL, 16 January 1988
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
