EuroNews: Love and rockets: Inside Italy's Vega launcher factory
...The tweet is in Dutch so I'll translate it. It's a tweet from the deputy of the province of South Holland (a part of the Netherlands). The tweet states:"On visit with Europarlementarian @C_Nagtegaal at @Airbus explanation about innovative solution to bring small satellites into orbit by Jeroen Rotteveel CEO @isis_space. @south_Holland Strong in Space(travel).It could also be another ride-share structure developed by Airbus Defence & Space the Netherlands (formerly known as DutchSpace)....
The current 4th stage uses UDMH and N2O4 as propellants. About 550kg on AVUM today, 740kg on AVUM+. Both propellants are not exactly dietary supplements.
Seems to be more about the Hydrazine ban in the EU. (Whenever that may happen.) Looks like N2O4 is also under additional scrutiny.I suppose it makes a better argument for satellite exemptions if you already removed a lot of the material from the launch system. Likely one of the arguments to finally retire the ES upper stage and replace it for Ariane 6. Probably also a problem for Soyuz at CSG since Fregat-MT carries 7100kg.
For me the interesting part is that M10 also looks like a landing engine for a P120C class booster. Just use a sea level nozzle. M10 is also supposed to be rather cheap.A dedicated landing engine is of course a bit special but Prometheus just does not throttle far enough.
I doubt that. Upper stage reuse is much harder and costs a lot of payload. (1:1 ratio)
Prometheus throttles to 30%. (via FR wikipedia) That is 30t thrust.You are right. 10t is not enough while 30t still a bit much. I guess there is always adding ballast. Or perhaps flying a really ineffective nozzle on the center engine.Apropos Space Rider. I'd like to see a Space Rider 2.0 soon. Include AVUM+ functions into the vehicle, switch to storable green propellants, and recover it all. No hypergolic upper stage, no expendable service module. Steal the weight for the additional structures and thermal shielding from the fairing because that is not really needed once someone does the ascent simulations without it.To me that is about reducing recurring cost. Not really to be used for any kind of satellite launching. Fly experiments.
Quote from: Chasm on 11/15/2018 07:08 pmI doubt that. Upper stage reuse is much harder and costs a lot of payload. (1:1 ratio)Hardware mass, yes. But you can come out ahead in propellant mass. Booster RTLS on Falcon 9 cuts payload capacity by, what, 30% to LEO, and about half that for downrange landing, because RTLS requires completely reversing course and even a downrange landing still needs a large reentry burn and a supersonic landing burn because its plunging straight down into the atmosphere. On the upper stage, reentry is more like a capsule or spaceplane, it gradually slows down and eventually becomes subsonic allowing for parachute landing (propulsive landing is better for rapid turnaround, but baby steps). No propellant needed other than for deorbit (which they should be doing whenever possible anyway, just for debris mitigation), and the only hardware addons (heat shielding, parachutes, possibly small aerosurfaces) are all quite light, maybe 1-2 tons for an Ariane 5/6-sized US.
Merlin only throttles to 40% or 34 t. So Prometheus at 30 t should be fine for a booster of comparable size to F9, or even quite a bit smaller.
Quote from: envy887 on 11/16/2018 12:34 pmMerlin only throttles to 40% or 34 t. So Prometheus at 30 t should be fine for a booster of comparable size to F9, or even quite a bit smaller.A lot smaller. P120C is only 12m long. With the stretch described above still less than half the length of the F9 first stageBasically a New Sheppard minus the ring fin and with too many engines. To me this idea of a P120 replacement is a quick fix to introduce reuse. As such it has to fit the current launchers. Emulating current performance or with any luck adding a bit.If reuse does not work out for any reason the introduction of Prometheus and clustered engines is still enough for me.Prometheus development is scheduled to end in Q2 2021 with IIRC 2 acceptance tested engines. According to the CNES Prometheus website the first flight is by 2030! That is way too long.If I was dictator benevolent leader of ESA/Ariane I'd like to see the expendable first test flight of this contraption by end of 2021. (6 months after engine acceptance) The only problem I can see is I also want a wound carbon fiber structure. Europe may or may not figure out how to wind a LOX tank that does not go boom until then. In case anyone is wondering I would still let Italy wind the structure. Trade the carbon wound P120C casing for carbon wound tanks.