Theoretical Maximum Velocity Of Electric Jet?

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Discussion Overview

The discussion revolves around the theoretical maximum velocities of supersonic electric aircraft, specifically focusing on the limitations of electric fan and compressor propulsion systems. Participants explore the factors that could influence the speed of such aircraft, considering various design and engineering aspects.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that the fastest aircraft have reached close to Mach 10 using rocket engines, implying that electric propulsion might face different limitations due to air characteristics.
  • Another participant argues that the speed limit of propeller-driven aircraft is not determined by the engine type, indicating that using an electric motor would not change the possible top speed.
  • A later reply clarifies that compressors, powered by electric motors, could be viable for supersonic flight, shifting the focus from fan propulsion to compressor propulsion.
  • It is noted that the axial flow compressor in a jet engine, which consists of rotating airfoils, does not perform well at supersonic speeds, suggesting that the limiting factors remain fundamentally the same.
  • One participant posits that achieving supersonic speeds may require technologies similar to scramjets.
  • Another participant mentions that traditional jets can achieve supersonic speeds without the air entering the compressor being supersonic, referencing the design of Concorde's intakes that slow air down significantly.

Areas of Agreement / Disagreement

Participants express differing views on the limitations of electric propulsion systems for supersonic flight, particularly regarding the effectiveness of compressors versus fans. The discussion remains unresolved with multiple competing perspectives on the topic.

Contextual Notes

Participants highlight the complexity of factors influencing supersonic flight, including aerodynamic design, power-to-weight ratios, and the nature of propulsion systems. There are unresolved assumptions regarding the specific limitations of compressor technology in supersonic applications.

Buggy
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I'm wondering about theoretical maximum velocities of supersonic electric aircraft. I think the fastest demonstration of any type of aircraft has been close to mach 10. This was done using a rocket engine, so propulsion would not be limited by air characteristics as much as a fan's propulsion would (I think).

Under best conditions; Assuming an incredibly high power to weight ratio of motors, extremely aerodynamic design, strongest materials, etc.

Theoretically, does anyone know what the limiting factors in the velocity of an electric fan propelled supersonic aircraft would be (barring energy use)? Does it depend on size, etc?

Could it reach mach 2+?

Thanks a lot in advance for any input.

EDIT: Please see question change below
 
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Buggy said:
Ah thank you, I've edited my original question based on this.
Please do NOT edit original posts. It makes things very confusing.
 
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Bystander said:
Please do NOT edit original posts. It makes things very confusing.

Okay sorry, changed it back. I will say what I want changed here:

Basically I initially thought propellers were the only way to go for electric craft (and propeller cannot go supersonic), but it appears that compressors are also viable with an electric motor (and compressor propelled craft can).

So the question now becomes what are the limiting factors for compressor-propelled craft (powered by electric motors) instead of the original 'for fan-propelled craft'
 
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In principle you could use anything to spin the front stage of a modern jet engine. You could use a gas turbine engine, a piston engine, an electric motor, a twisted rubber band or even a human on a push bike.
 
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Buggy said:
So the question now becomes what are the limiting factors for compressor-propelled craft (powered by electric motors) instead of the original 'for fan-propelled craft'
The axial flow compressor in a jet engine is still made up of rotating airfoils (like a prop) so still don't perform well at supersonic speeds and the limiting factors are fundamentallly the same.
 
billy_joule said:
The axial flow compressor in a jet engine is still made up of rotating airfoils (like a prop) so still don't perform well at supersonic speeds and the limiting factors are fundamentallly the same.
So essentially to go supersonic at all you need some sort of scramjet type technology?
 
A traditional jet can go supersonic without the air entering the compressor being supersonic.
 

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