what's old is new again ...

[rb1957]

from flight ...
Embraer tweaks turboprop concept to have aft-mounted engines ...

didn't Boeing try this in the 90s ?

another day in paradise, or is paradise one day closer ?

 

[MintJulep]

It occurs to me that if you put the engine shown by jaceb in his picture inside a cylinder that you could improve things by reducing radial flow, and maybe control noise as well.

Maybe I should patent that idea before anyone else thinks about it.

 

[rb1957]

I've been wondering what it'd be like if you replaced the hot section with an electric motor. How much thrust from just the LP fan ?

another day in paradise, or is paradise one day closer ?

 

[MintJulep]

I've been wondering what it'd be like if you replaced the hot section with an electric motor.

Doesn't that get us to thread2-486123?

 

[rb1957]

if you dump the nacelle and 1/2 the blades.

another day in paradise, or is paradise one day closer ?

 

[jaceb]

the point is to have bigger fan/propeller/propfan without drag penalty coming out from enormous nacelle, actually for contemporary engines fan is responsible for generating around 80%+ of thrust, and yes - its spinning fast enough to exceed Mach 1 at the tip (dont ask how this vanes will help with this fact - this is sweet secret of the CFD peoples from GE), for the narrow body engine engine you will need (i had this number somewhere at the back of my head) 20MW+ of power - your heat rejection in this case will be 200kW from electric motor and additional 100kW from gearbox if you have any + inefficiencies coming out from power conversion system - but this again will lead us to the discussion on the electric propulsion suitability for the aircrafts - probably all of us have their own opinions related to this one.

 

[jaceb]

about question what problem we are trying to solve - 2050 is declared date for carbon neutral economy - 2035 is the deadline for 50% reduction in CO2 emission - at least in EU. Considering all options we have on the table - in my opinion - only workable one is significant increase in fuel economy of aircrafts which is possible only with turboprop type propulsion. All other options are in best case niche filling (read BS). Of course alternatively we may stop flying and start walking and chatting with friends from other side of Atlantic via internet.