Tuesday, July 7, 2015

Ariane 5 Core plus 4 Ariane 4 side-boosters as a manned launcher, page 2: use as another ISS supply vehicle.

Copyright 2015 Robert Clark

  In the blog post "Ariane 5 Core plus 4 Ariane 4 side-boosters as a manned launcher", I suggested such a configuration would give a quicker, cheaper implementation of the Ariane 6 that would have the advantage that it could also be used as a manned launcher. 

Ariane 5 Core plus Ariane 4 side boosters added

 A recent news report gives this even greater importance, the fact that France wants to sell its stake in Arianespace to Airbus Safran:

French Divestment Will Put Arianespace in Airbus Safran’s Hands.
by Peter B. de Selding — June 10, 2015

 This is good news for the commercial space approach to lowering launch costs. For instance, the use of solid rocket side boosters on the Ariane 6 helps to subsidize the French military's use of solid rocket missiles. Without the French government owning a part of the company, you are freer to choose the most cost-effective approach instead.

GEO satellite launcher.
 The calculation for this configuration without an upper stage was for 15 metric tons(mT) to LEO. Much of the satellite launch market however is to geosynchronous orbit. Using an existing upper stage for this version would eliminate another development cost for the current version of the Ariane 6 which envisions a new large upper stage using the new Vinci engine.

 For this configuration use instead the already developed Ariane H10-3 upper stage. This has a 1,570 kg dry mass, 10,470 kg propellant mass, 62.7 kN vacuum thrust and 446 s vacuum Isp. Plug these numbers in for the upper stage into Schilling's launch performance calculator with the same numbers for the Ariane 5 core and Ariane 4 liquid-fueled side-boosters as used in the "Ariane 5 Core plus 4 Ariane 4 side-boosters as a manned launcher" post.

 For GEO satellites the launchers actually send the satellites to geosynchronous transfer orbit (GTO) which is a highly elliptical orbit that reaches from LEO to GEO, with the satellites onboard propellant and engines providing the final kick to a circular orbit at GEO. For the GTO orbit, enter in Schillings calculator the default perigee of 185 km, 35,000 km for the apogee, and an inclination of 5.2 degrees to match the latitude of the Ariane launch site. Then the calculator gives the results:

Mission Performance:
Launch Vehicle:  User-Defined Launch Vehicle
Launch Site:  Guiana Space Center (Kourou)
Destination Orbit:  35000 x 185 km, 5 deg
Estimated Payload:  7948 kg
95% Confidence Interval:  6380 - 9952 kg

"Payload" refers to complete payload system weight, including any necessary payload attachment fittings or multiple payload adapters
This is an estimate based on the best publicly-available engineering and performance data, and should not be used for detailed mission planning. Operational constraints may reduce performance or preclude this mission.

Lowered development costs reduces launch pricing. 
 Replacing the solids with the liquid-fueled boosters that had already been used on the Ariane 4 would eliminate the development costs of having to develop the new solids now planned for the Ariane 6. Since the need to recoup development costs amounts to a significant proportion of the launch price of rockets, the minimal additional development costs would make it much easier for this version of the Ariane 6 to meets its low launch cost goals. And in addition to the much lowered development costs, the minimal additional development would lead to a rapid route to its deployment.

 Also, ESA is considering some versions of the reusability in returning the engine compartment of the core stage. However, by using liquid side boosters you can make the side boosters reusable as well by doing a vertical landing on those.

 Inexplicably, in ESA trade analyses of liquid-fueled versions for the Ariane 6 versus solid booster versions, no consideration was given to the major advantage of liquid fueled versions of providing Europe with an independent manned launch capability. Note this all liquid implementation would give a manned vehicle using four liquid-fueled boosters attached to the core stage, as both the
Russians and the Chinese have done to produce their manned launchers. And because of the rapid development time due to the minimal new development needed, Europe could probably field this manned launcher by the time the Americans field theirs, expected in 2017.

Use as an ISS supply vehicle.
 Last months failure of the Falcon 9 launch to resupply the ISS reveals another reason such fast development time is important. All three of the current ISS cargo launchers have experienced recent launch failures. Then another launcher to serve as a cargo supply vehicle would be useful. Because it would have a short development time and low development cost, this version could serve as valid alternative to the other launchers. Then this opens up another revenue source for this all-liquid version of the Ariane 6.

 Moreover, the Cygnus capsule, being European, could also be used as a low cost cargo capsule, rather than the expensive ATV.

     Bob Clark

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