Rockets, of all the jet engines, indeed of essentially all engines, have the highest thrust to weight ratio. This is especially true for liquid rocket engines.
This high performance is due to the small volume of pressure vessels that make up the engine—the pumps, pipes and combustion chambers involved. The lack of inlet duct and the use of dense liquid propellant allows the pressurisation system to be small and lightweight, whereas duct engines have to deal with air which has a density about one thousand times lower.
|Jet or Rocket engine||Mass|
|RD-0410 nuclear rocket engine||2,000||4,400||35.2||7,900||1.8|
|J58 jet engine (SR-71 Blackbird)||2,722||6,001||150||34,000||5.2|
|Rolls-Royce/Snecma Olympus 593|
turbojet with reheat (Concorde)
|Pratt & Whitney F119||1,800||3,900||91||20,500||7.95|
|RD-0750 rocket engine, three-propellant mode||4,621||10,188||1,413||318,000||31.2|
|RD-0146 rocket engine||260||570||98||22,000||38.4|
|SSME rocket engine (Space Shuttle)||3,177||7,004||2,278||512,000||73.1|
|RD-180 rocket engine||5,393||11,890||4,152||933,000||78.5|
|RD-170 rocket engine||9,750||21,500||7,887||1,773,000||82.5|
|F-1 (Saturn V first stage)||8,391||18,499||7,740.5||1,740,100||94.1|
|NK-33 rocket engine||1,222||2,694||1,638||368,000||136.7|
|Merlin 1D rocket engine||440||970||690||160,000||159.9|
Of the liquid propellants used, density is worst for liquid hydrogen. Although this propellant is marvellous in many ways, it has a very low density, about one fourteenth that of water. This makes the turbo pumps and pipework larger and heavier, and this is reflected in the thrust-to-weight ratio of engines that use it (for example the SSME) compared to those that do not (NK-33).