4 ms·

Wonder how much contrails are created by rockets? If we'd move the travel above the atmosphere, how much could be saved? An alternative is to move back to slow

by avmich 7y ago

Wonder how much contrails are created by rockets? If we'd move the travel above the atmosphere, how much could be saved? An alternative is to move back to slower propeller planes, maybe with electric motors (improving over Tu-95?) but that would increase flight times.

mc32 7y ago
Aren’t those less efficient and less reliable as well? I don't see going back to props. What's the mean time before overhaul on both? Also lower ceiling.
- avmich 7y ago
  Rockets - perhaps, for today, but maybe they could be improved. Propeller planes - why? They were used for long time and many technologies are quite mature.
  - thecount122195 7y ago
    Propellers have a fundamental speed limit on them, the tips can not exceed the speed of sound or else shock waves form which cause the efficiency to drop off sharply, as well as creating massive noise pollution from the sonic boom constantly coming off the propeller. Todays commercial "jet" engines are actually closer related to propeller planes than pure jets, turbofans provide the majority of their thrust from the ducted fan rather than the jet exhaust coming out the back.
- ataturk 7y ago
  You can each have an ejector seat.
astrodust 7y ago
A large part of the propulsion of a modern turbofan jet plane is provided by so-called "bypass" air, air that flows around the core of the engine. If you can spin those turbine blades electrically you can get nearly as much thrust as the jet version. The challenge is in finding out how to do this. You could do this with some other mechanism if you can come up with a way of storing lots of energy in a liquid or solid that isn't too heavy. Some discussion here: https://aviation.stackexchange.com/questions/26910/could-an-electric-engine-provide-the-same-performance-as-jet-engines-on-current https://aviation.stackexchange.com/questions/26910/could-an-...
saltcured 7y ago
Most of the visible contrail seems to come from engine emissions, though you can also see condensation effects purely from the dynamic pressure changes around the plane. Those are more obvious with fighter jets and acrobatic planes though, where they are generating more severe aerodynamic effects rather than sustained level flight. Assuming the visible contrail correlates well with the part causing climate effects, an electric ducted fan might be a big improvement, by removing the combustion emissions. I don't know if some other fuel-burning engine could be combined with a ducted fan and sufficient emission controls to also serve this purpose.

by avmich 7y ago

mc32 7y ago

Aren’t those less efficient and less reliable as well? I don't see going back to props. What's the mean time before overhaul on both? Also lower ceiling.

avmich 7y ago
Rockets - perhaps, for today, but maybe they could be improved. Propeller planes - why? They were used for long time and many technologies are quite mature.
- thecount122195 7y ago
  Propellers have a fundamental speed limit on them, the tips can not exceed the speed of sound or else shock waves form which cause the efficiency to drop off sharply, as well as creating massive noise pollution from the sonic boom constantly coming off the propeller. Todays commercial "jet" engines are actually closer related to propeller planes than pure jets, turbofans provide the majority of their thrust from the ducted fan rather than the jet exhaust coming out the back.
ataturk 7y ago
You can each have an ejector seat.

astrodust 7y ago

A large part of the propulsion of a modern turbofan jet plane is provided by so-called "bypass" air, air that flows around the core of the engine. If you can spin those turbine blades electrically you can get nearly as much thrust as the jet version. The challenge is in finding out how to do this. You could do this with some other mechanism if you can come up with a way of storing lots of energy in a liquid or solid that isn't too heavy. Some discussion here: https://aviation.stackexchange.com/questions/26910/could-an-electric-engine-provide-the-same-performance-as-jet-engines-on-current https://aviation.stackexchange.com/questions/26910/could-an-...

saltcured 7y ago

Most of the visible contrail seems to come from engine emissions, though you can also see condensation effects purely from the dynamic pressure changes around the plane. Those are more obvious with fighter jets and acrobatic planes though, where they are generating more severe aerodynamic effects rather than sustained level flight. Assuming the visible contrail correlates well with the part causing climate effects, an electric ducted fan might be a big improvement, by removing the combustion emissions. I don't know if some other fuel-burning engine could be combined with a ducted fan and sufficient emission controls to also serve this purpose.