Does anyone know the reason why the PS4 stage in PSLV sits right inside the payload fairing? Was it a weight saving measure?
Quote from: vineethgk on 01/10/2017 07:55 amDoes anyone know the reason why the PS4 stage in PSLV sits right inside the payload fairing? Was it a weight saving measure?Just look at your picture again. What other reasonable options would there be when the tank is so small?
Atlas V 5 m versions have half the Centaur in the fairing, Star 48 on Delta II was/is, Waxwing was on Black Arrow, and I'm pretty sure there's been more small solid upper stages in the fairing in early rockets.
I must admit I'm a perfect noob when it comes to principles of LV design. But is it usual for the rockets with smaller upper stages to have them within the payload fairing rather than as a separate unit? I mean, the problem I see here is that you would need to have real clean room in the vehicle assembly building so that they can enclose the payload within the payload fairing there.
Look at how Soyuz integrates the Fregat or Proton the Briz-M or Blok-D.
Although development of Heavy lift launchers are important, we also need Agni V based launch system & 500 kg payload variant of PSLV to remain competent in the launch market.
Yet another PSLV launcher question that has been floating around my mind. PSLV's (and GSLV's) S-139 solid motors are composed of 5 segments, while GSLV-III's newer (and larger) S-200 is composed of only 3. Wouldn't it save ISRO technicians valuable time in stage integration if the S-139 segments were to be redesigned to make them larger, so that the fully assembled motor would be simpler, say of 2 segments ? (Or maybe even attempt to make it a single segment motor like the P-120 Europeans plan for Ariane 6 and the new Vega, though it might be far more challenging.) Apparently, they did manage to make larger segments for S-200 in any case.Or would the added cost or the risk of change in vehicle characteristics negate any advantages of such a move?
PSLV uses a solid motor in its third stage (PS3), which is of 2 m diameter and 4850 litre capacity. PS3 motor case weighing 325 kg was initially realised by filament winding process using Aramid/Epoxy for the construction for the shell and Carbon/Aramid/Epoxy hybrid construction for the skirt extension. Four numbers of PS3 motor cases were burst tested and gave more insight into the processing and design of composite motor case. It was observed that polar winding potential was underutilised due to non-uniform stress distribution and unequal opening, high boss opening ratio and fast-indexed multi star pattern in polar winding. Hence the design and processing parameters of PS3 motor case were optimised to augment the payload capacity of PSLV to meet the future requirements of ISRO.High Performance motor case (HPS3) is the improved version of PS3 motor case. An optimum design for this was evolved by selecting appropriate different profiles for both the domes, introducing dome reinforcements and adopting modified helical winding with wide band in multi axis filament winding machine.