/sci/ - Science & Math

Today I did some calculation and I realised that Long March 2-3-4 series indeed have half-decent mass fraction (at least on the Hypergolic stages, the , the myth of shit Chinese mass fractions is indeed kind of a myth, or at least it doesn't compare badly with Proton and Ariane 4

based on the User guide http://www.cgwic.com/LaunchServices/Download/manual/LM-3A%20Series%20Launch%20Vehicles%20User's%20Manual%20Issue%202011.pdfp

and picrel from a South Korean space agency presentation from last month

When running these numbers the chinks officially give with silverbird and on my own I do get coherent results with what they advertise (and what has been flight-proven), If I adjust the ISP they give for S1/booster (Sea level) to the average over their trajectory I can get equally coherent results with slightly worse mass fractions (1-3% heavier)... but it's never bad, just at worse a bit heavier than Proton.

Hypergolic stages can be lighter (kinda) compared to semi-cryo and cryo stages, but clearly the Chinese don't have an abnormaly heavy structure due to inferior technologies as is often repeated. Their hydrogen stages are still behind the americans no matter what in term of mass fraction.

--
The more I think about it the more it makes sense
In term of architecture their rocket is basically like an Ariane 44L, although with a bit more mass on S2/S3 and a bit less on S1, although with less efficient (10+ isp) engines
yet they manage to surpasse Ariane 44L in performances to both GTO and LEO by 10-20%