Towards a manned Indian launcher: an all-liquid LVM3.

 Copyright 2024 Robert Clark

 In the blog post, "A liquid-fueled Indian manned launcher. UPDATED", I suggested the launcher based on the liquid-fueled LVM3 core stage, but replacing the 2 solid side boosters by 4 of the liquid-fueled strap on boosters used on the earlier design, the GSLV Mk. II. Here I'll suggest instead a version using the LVM3 core but getting the added thrust needed for lift-off by adding a 3rd Vikas engine.

GSLV Mk. III Specifications

I have argued using such large SRB's are not price competitive:

Towards a revolutionary advance in spaceflight: an all-liquid Ariane 6.

It is very likely the same is true for the GSLV Mk  III. Then we'll replace the two SRB boosters by an additional core engine.

 The GSLV Mk. III core stage has specifications listed as:

Core Stage

Type	L-110
Length	21.26m
Diameter	4.0m
Fuel	Unsymmetrical Dimethylhydrazine
Oxidizer	Nitrogen Tetroxide
Inert Mass	10,600kg
Propellant Mass	115,000kg
Launch Mass	125,600kg
Propellant Tanks	Aluminum Alloy
Fuel	UH25 - 75% UDMH, 25% Diazane
Oxidizer	Nitrogen Tetroxide
Propulsion	2 Vikas 2
Thrust (SL)	677kN
Thrust (Vac)	766kN
Specific Impulse	293 sec
Engine Dry Weight	900kg
Engine Length	2.87m
Engine Diameter	0.99m
Chamber Pressure	58.5bar
Mixture Ratio	1.7 (Ox/Fuel)
Turbopump Speed	10,000rpm
Flow Rate	275kg/s
Area Ratio	13.88
Attitude Control	Engine Gimbaling
Ignition	T+110s
Burn Time	200s
Stage Separation	Active/Passive Collets

 The Vikas 2 engine provides a thrust of 677 kN at sea level, 69 tons-force. The two on the core would be enough just to loft the core only. But we need enough thrust to liftoff a second stage and payload also. So we'll give the core a third Vikas engine.

 The weight of the Vikas is 900 kg. Then the dry mass of the stage with an additional Vikas will be 11,500 kg. 

The cryogenic upper stage has specifications listed as:

Cryogenic Upper Stage

Type	C-25 Cryogenic Upper Stage
Length	13.32m
Diameter	4.0m
Fuel	Liquid Hydrogen
Oxidizer	Liquid Oxygen
Inert Mass	~4,000kg
Propellant Mass	25,000kg
Launch Mass	~29,000kg
Propellant Tanks	Aluminum Alloy
Propulsion	CE-20
Engine Type	Gas Generator
Thrust - Vacuum	200kN
Operational Range	180-220kN
Specific Impulse Vac	443s
Engine Mass	588kg
Chamber Pressure	60bar
Mixture Ratio	5.05
Area Ratio	100
Thrust to Weight	34.7
Burn Time	580s
Guidance	Inertial Platform, Closed Loop
Attitude Control	2 Vernier Engines
Restart Capability	RCS for Coast Phase

  Now plug in the data for the Silverbirdastronautics.com payload estimator:

Where we assume by just using a nozzle extension the Isp can be raised from 443s to the 465s max Isp of the RL10 engine.

 The resulting payload to LEO is:

 This is half the 10 ton payload of the current version of the LVM3 with the large solid side boosters. However, it has the advantage of not using the problematical solid side boosters with their safety concerns for manned flights. 

 The all-liquid version is also likely to be significantly cheaper than the one with solid side boosters as large solid boosters are not price competitive to just using an additional liquid fueled engine.

It is notable a 5 ton class launcher is sufficient to launch a crewed capsule to orbit since the Gemini capsule had a toal mass of 3,800 kg:

GEMINI SPECIFICATIONS

First flight: 8-Apr-1964; first manned flight 23-Mar-1965 (Gemini 3)
Last flight: 11-Nov-1966 (Gemini 12)
Number of flights: 13 total; 10 manned
Principal uses: manned earth orbit rendezvous, docking, EVA tests
Unit cost: $13.00 million
Crew size: 2
Overall length: 5.7 m
Maximum diameter: 3.05 m
Habitable volume: 2.55 m3
Launch mass: 3,851 kg
Propellant mass: 455 kg total
RCS total impulse: 1,168 kNs
Primary engine thrust: 710 N
Main engine propellant: NTO/MMH
Total spacecraft delta v: 323 m/s
Power: fuel cells/batteries; 155.0 kWh total
https://www.braeunig.us/space/specs/gemini.htm

 The payload to LEO also can be increased by weight optimizing the first stage. The stage is similar to the first stage of the Titan II that launched the Gemini capsule to space, except the Titan II's first stage dry mass was 6,000 kg less. Reducing the first stage dry mass input in the SilverbirdAstronautics.com payload estimator by 6,000 kg increases the payload to ca. 6,000 kg. 

  Robert Clark