Kermann Nolandung

ESA is the intergovernmental space agency that coordinates the european space programmes. Eventually the budget, programmes and member participations are voted by the member states. In ESA there are mandatory programmes where each member state contributes an amount proportional to their gross national product and optional programmes. The launchers are optional programmes, the members are free to participate or not. It should be noted that ESA is not a sub-organization of the European Union but a different one. Alongside ESA, some members have their own national space agency (CNES, DLR, ASI…). Arianespace is the company in charge of providing launch service from Kourou spaceport. Its offer includes launch with Ariane, Vega and formerly Soyuz from Kourou. ArianeGroup is a joint venture of aerospace companies (with activities mainly in France and Germany) that was recently formed to develop and build Ariane 6 launcher. The share of the work of the prime and sub-contractors is then divided between the members in proportion to their participation. Vega is a launcher developed and manufactured by Italian agency and companies. The manufacturer is Avio. Last year, Italy and Avio negotiated that future Vega launches would no longer have to be marketed through Arianespace. That means it becomes a new competitor. With Ariane 6, unlike the previous generations, ESA has entrusted ArianeGroup, a private company, with the development of the rocket. This company is supposed to develop the launcher within a fixed budget and assume the risks. We can see where they are today. The company is calling for a budget increase and members complain about the extra costs. ArianeGroup seems easily to blame, but I guess nobody (ESA, members, ArianeGroup, contractors) is clean. One issue is that it has to follow the principle of geographical return. For example, ArianeGroup’s CEO has revealed that while he engaged cost reduction in his company, he faced dramatic increase in costs from subcontractors (some of whom, understandly, come from countries that complain about the cost of the programme). Who to blame ? If I were one of the CEO of one of the subcontractors, it would be my duty to make the most of it from a kind of a monopol situation. I don’t know the contractual details, but I can imagine a lot of reasons for the delays, extra costs and tense discussions.

I'd really like to see a DLC that gives a realistic flavour to KSP2 and would include: - An intermediate scale solar system (x3?) at least for Kerbin and Mun. Reaching orbit on Kerbin should be far more demanding than a suborbital jump. - Patch-conic physics is all very well. But introducing a fictitious J2 effect (a fake Kerbin’s oblateness) on the low orbit would allow an orbit precession that would make a sun-synchronous orbit possible. - An automation and control language (like Vizzy or kOS?) that allows us to control our launcher or spacecraft in a reproducible way. - If not purposely designed, motors should have limited thrust modulation and re-ignition capabilities. I recognise that an engine that could not be modulated would not be playable by human control, so we could imagine that a non-variable thrust engine would only be allowed to modulate down to extinction. With theses limitations, monergol will be of great interest. - Liquid engines would be differentiated between MetalOx and HydroLOx to allow us to choose between a high-density liquid fuel and a low-density liquid fuel. - For re-entry capsules, we would add a selector that would shift the centre of mass, this misalignment being intended to introduce a natural angle of attack and lift.

Well, I was wrong. Ariane 5 User's manuel gives 4540 kg for the dry mass. The illustration on this website gives aditional details. It includes 900 kg for the Inter Stage Skirt, but the VEB is excluded. The VEB changed between A5 G and A5 ECA. Something from 1450 kg to 950 kg when the aluminium structure has been replaced by composite structure. Acme Engineering (acme-engineering.nl)

I won't help you much but I read your interrogation regarding ESC-A upper stage. I think someone has mixed up kg and lbs values of the empty mass (2100 kg / 4600 lbs) and spead the error on internet (at least on the English, French and German Wikipedia pages). I guess we should consider for ESC-A Empty mass 2100 kg (instead of 4600 kg) Fuel 14400 kg Gross mass 16500 kg (instead of 19 t) As stated here : Ariane 5-2 ESC A (astronautix.com)

I'd like that too. If I am not mistaken, I understand that a scale of around x3 is more consistent with the characteristics of the parts. I would even be willing to buy a DLC aimed at experienced players and that would include one or several intermediate scales, among other things. Once the core engine has been fine-tuned, I don’t think it will require much development effort.

If I am not wrong on Ariane 5, the boosters apply the thrust to the upper part of the core stage. I guess, it permits a lighter structure and would explain the large payload fraction. If you remove the booster, I think you have to use about the same mass ratio as Delta IV.

There in 2019, there is some mix between euros and dollars : Space launchers: restoring Europe's space ambition - Senate (www-senat-fr.translate.goog) On the one hand, the price per kilo put into orbit has fallen since 2014 . Although no official communication on marketing prices has been made by Arianespace, the press has reported the following orders of magnitude: 130 million dollars for Ariane 64 and 80 million dollars for Ariane 62 versus, as we have seen , a Falcon 9 priced at less than $50 million in the commercial market 67( * ) . Worse, this price difference would be justified by a difference in production cost: according to the same source, the cost targets were 90.6 million euros for an Ariane 64 and 73.6 million euros for an Ariane 62 68( * ) against, as already mentioned, a cost of 44 million dollars for a consumable Falcon 9 launch .

I guess adapting an expensive engine that was not designed to be reused and is moreover HydroLOx is just a dead-end. About the cost of SRBs, in a parliamentary report I found references that say prices 130 M€ for Ariane 64 and 80 M€ for Ariane 62 but it target costs 91 M€ for Ariane 64 and 74 M€ for Ariane 62. It don't know if there are up to date, but it reduces the cost of two boosters to 17 M€. I'm not very surprised, as optimizing booster production compare to A5 was a key argument to justify the Ariane 6 architecture.

I always heard that hydrolox engines introduce much complexity hardly compensated by the fuel efficiency. And to get a reusable stage, I guess the engine has to be able to modulate its thruttle. On the Falcon rockets, the design was simplfied to get only 2 stages and a single engine type, that leads some ways to optimize the production. Actually the current Ariane 6 is not the most cost effective configuration that was studied. It is was a compromise between the different countries. Full solid fuel boosters on its lower stages appeared to be cheaper, Ariane 6 life will be quite short, currently there is a developpement for a MethaLOx variable thrust engine (Prometheus) that is reusable, with a goal to be one-tenth the cost of the Vulcain.

Ariane cannot compete with SpaceX, they do not operate in the same markets. The launches subject to competition represent only a fraction of the total. SpaceX benefits from the U.S. market for institutional launches and launches of its own constellation. This situation cannot be compared to European institutional launches (which are not required to be launched by a European rocket). The economic equation of a reusable rocket puts Ariane at a disadvantage compared to SpaceX. The question that arises is how to build a rocket that minimizes the cost of sovereign access to space. The commercial price is only defined to diluate that cost on commercial launches.

KSP2 version : 0.1.1.0.21572 It seems that some aerodynamic parts are misclassified in the VAB. I would expect parts with a control surface to be filed in the control surface folder while those without a control surface would be filed in the stabiliser folder. Currently the VAB shows this: Stabilizer folder LAF-125 (XS): Control surface available : no LPS-250 (SM): Control surface available : yes MPS-500 (MD): Control surface available : yes HPS-1000 (LG): Control surface available : yes Control Surface folder LPCS-250 (SM): Control surface available : no MPCS-500 (MD): Control surface available : no HPCS-1000 (LG): Control surface available : no

Anyway, only two Ariane 5 remain. She is no more built. ESA took a gamble that Ariane 6 will take over on time et decided to stop Ariane 5 production. In case of delay, Arianespace would have partially relied on Soyuz launched at Kourou and Vega but we know story and no proven rocket is available today.

With patched conic, the motion is described in a locally inertial reference frame, this is quite practical. If we go with n-body physics, in addition to the other gravitational forces, we must take into account the forces of inertia if we are not in the kerbol frame and we can continue as well with J2, solar pressure and even satellite emissivity. I can see some interest for few specific missions. In this case, why not install on these specific probes or vessels a massless engine that simulates all the orbital disturbances encountered while still remaining within a keplerian motion.

We do not need n-body physics. The patched conic approximation is not without interest considering that it is/was actually used for mission planning. At least it makes the navigation calculations accessible to the player and the orbital parameters remain fixed in the absence of thrust. I don't see the point of putting in an overly complicated model that requires extra computational resources, and then having to push a button on a mod that calculates the optimal trajectory automatically. You can play with matlab, gmat or whatever for that. What I would like to see is a fictitious oblatness with a J2 effect on the orbit drift that only works when the physic is on rail. This would allow a Kerbol-synchronous orbit.

The pound has a definition in imperial units, but it also existed in various other measurement systems. It may be recalled that the ounce used today for trading precious metals inherited one of them (1 troy ounce ≈ 1.097 ounces). Although I live in an all metric country, I remember going to the market with my grandmother and asking the butcher for a pound or half pound of meat, here a pound meant 500g. so 1 pound = 500g is my preference I wonder if this informal usage is widespread in Europe. I found out that this is the definition given in the customary measurements system in France. https://en.wikipedia.org/wiki/Mesures_usuelles