Talk:Propulsive efficiency

Typical Propulsion Efficiency Values
Would be nice to see P.E. values for the type of engines mentioned, say, at normal cruise speed. Also, could P.E. figures for the Ion Engine be given as well? Thanks. Tony (talk) 17:28, 31 October 2011 (UTC)

Oberth effect?
Is the Oberth effect about propulsive efficiency? I'm not sure that's the case. Maybe this should be discussed and straightened out. DonPMitchell (talk) 21:26, 26 September 2015 (UTC)

Assessment comment
Substituted at 03:28, 30 April 2016 (UTC)

confusing mechanical and propulsive efficiencies
The article confuses between mechanical efficiency and propulsive efficiencies.

The propulsive efficiency (eta_p) is the ratio of useful power used to propel a vehicle to the available power in a jet. It is equal to (Thrust*VehicleVelocity)/JetKineticEnergy

The mechanical efficiency (eta_m) is defined as the useful mechanical power available at a shaft relative to the power input. It is defined for SHAFTS. It should not appear in this article except may be as an analogy of the propulsive efficiency for engines powering shafts.

This article is called propulsive efficiency, therefore it should focus on propulsive efficiency, not on overall efficiency and not on mechnical efficiency. Amgadoz (talk) 05:00, 14 June 2020 (UTC)

Section on propulsive efficiency of propeller does not actually deal with propulsive efficiency
Propulsive efficiency is independent of mechanical efficiencies. It depends on nothing except the velocities and massflows entering and exiting the propulsor. The question which propulsive efficiency answers is "how much thrust do we achieve for a given amount of power applied to the air?" I'm out of time for today, but I am sure there is some good material on this available either from NASA, from Mark Drela, who usually writes very understandably, or in one of the standard books on aerospace engineering.

The information in the section on propellers is not useless, and I have no reason to believe it to be wrong, but I'm sure that it belongs in another place, since it does not deal with propulsive efficiency. — Preceding unsigned comment added by 2001:980:5F25:1:1692:C4FD:B0BA:71FA (talk) 20:16, 15 December 2021 (UTC)