AbstractReusability is anticipated to strongly impact the launch service market if sufficient reliability and low refurbishment costs can be achieved. DLR is performing an extensive study on return methods for a reusable booster stage for a future launch vehicle. The present study focuses on the vertical take-off and vertical landing (VTOL) method. First, a restitution of a flight of Falcon 9 is presented in order to assess the accuracy of the tools used. Then, the preliminary designs of different variants of a future Ariane launch vehicle with a reusable VTOL booster stage are described. The proposed launch vehicle is capable of launching a seven ton satellite into a geostationary transfer orbit (GTO) from the European spaceport in Kourou. Different stagings and propellants (LOx/LH2, LOx/LCH4, LOx/LC3H8, subcooled LOx/LCH4) are considered, evaluated and compared.[/b]
This doesn't belong in this thread, but i'm not sure it's worthy of its ownhttp://elib.dlr.de/114430/1/Paper_IAC2017_D.2.4.3ENTRAIN.pdfEvaluation of Future Ariane Reusable VTOL Booster stages
Quote from: savuporo on 10/03/2017 04:42 amThis doesn't belong in this thread, but i'm not sure it's worthy of its ownhttp://elib.dlr.de/114430/1/Paper_IAC2017_D.2.4.3ENTRAIN.pdfEvaluation of Future Ariane Reusable VTOL Booster stagesSection 2.2 mentioned that they estimated F9s performance is reduced by 30%-35% with DRL, and 60%-65% with RTLS. Amazing
I haven't read the whole paper yet, but the statement "Once again the relevance of a launcher with a gross lift-off mass of about 3800 tons is very questionable." jumped out at me.The major consequence of a reusable booster is that lift-off mass is almost irrelevant, cost is booster manufacturing/flights + fuel + opps, for a reasonable number of reflights booster manufacturing costs (which depend heavily on lift-off mass) are amortised to a low level.
The preliminary sizing of a LOx/LCH4 version with a first stage performing a RTLS has been performed for the upper stage ∆V of 7.6 km/s. Due to the lower specific impulse compared to the LOx/LH2 propellant combination the first stage propellant loading has to reach 3020 tons of which about 500 tons are needed for the RTLS. The upper stage propellant loading has been estimated to be 450 tons, or larger than the first stage of Falcon 9. Once again the relevance of a launcher with a gross lift-off mass of about 3800 tons is very questionable.
The LOx/LH2 launcher with an upper stage ΔV of 7.0 km/s is lighter than a Falcon 9 and delivers 2 tons more payload to GTO (7500 kg vs 5500 kg) in DRL mode.
QuoteThe LOx/LH2 launcher with an upper stage ΔV of 7.0 km/s is lighter than a Falcon 9 and delivers 2 tons more payload to GTO (7500 kg vs 5500 kg) in DRL mode.This is very interesting. The expendable portion is still large at ~88 tons, this would be half the size of the Ariane 5 core and one of the largest upper stages in history. But the Falcon 9's upper stage is also extremely large.But why didn't they investigate mixed launchers with a methane lower stage and hydrogen upper stage?
Vehicle Layout:<snip>The reference vehicle has a diameter of around 1m, with a total height around 13m. It is equipped with two main external features compared to a classical operational launcher:- Deployable fins, which are folded during ascent and are unfolded during the ballistic phase before reentry :they enable to stabilize and control the vehicle during its atmospheric entry- Four landing legs, which are also folded during ascent and deployed very shortly before landing. Apreliminary design has been done with the objective of ensuring both sufficient engine clearance withrespect to ground and stability at touchdown.
Is that some sort of air entrainment shroud at the bottom?
No one noticed the CSG image with ELA4 ilustrated on it.
I found a paper on Prometheus that was not yet posted.The obvious application would be for an Ariane 7 with 7 engines, a configuration similar to Falcon 9 or New Glenn.