Assuming you didn't have to make it flyable at low speeds for take off and landing how feasible is it to make a small supersonic plane powered by electricity?
The best brushless motors peak power output to weight ratios compares favorably to miniature turbines. But existing electric ducted fan planes usually end up with a top speed of around 700km/h as they can't accelerate air much faster than that.
Assuming you had around 20KW of power to use is there anyway to translate that into thrust capable of supersonic speeds? Would using intake ramps to slow the air to subsonic speeds then compressing it with the fan and sending it through a variable nozzle that decreases in size at higher speeds work?
I have seen people speculate that at higher speeds it might be more effective to switch something similar to an electric ramjet where compressed air is rapidly heated via a plasma arc or other heating element. But there's very little information regarding possible supersonic electric planes in general.
> is it to make a small supersonic plane powered by electricity?
Figure it out yourself.
We are not your wetware CPU's.
Noah Morris
I remember reading about a material that when water droplets move across the flat surface, it will generate electricity. Build the exterior out of this material, and at supersonic speeds it can power itself when passing through clouds.
Zachary Sanchez
thats basically drawing a small current from frictional forces.
supersonic speeds are achievable by combustion because it gives tons of energy in heat and pressure to a gas, how would you do the same with electricity?
I'm not sure if its possible to accelerate air beyond supersonic speeds using a propeller.
Hunter Lee
calculate it yourself. Also, wave drag is a drag.
Grayson Taylor
>supersonic speeds are achievable by combustion because it gives tons of energy in heat and pressure to a gas, how would you do the same with electricity? >I'm not sure if its possible to accelerate air beyond supersonic speeds using a propeller. That's the issue, technically the electric vehicle has more power but energy density is lower so range would be reduced. However it's not difficult to have batteries capable of 500A at 100V for a small drone 1 or 2 meters in size, it won't fly for very long but the power output would be 5x higher or more than hobby jet engines.
But the question is how to efficiently convert electrical energy into thrust at supersonic speeds. The only proposal I have seen is to use conventional ducted fans up to around 500km/h then switch to an electric jet engine, the inlet slows the air to subsonic speeds and compresses, then an axial compressor driven by an electric motor further compresses it 8:1, it's then ejected into a chamber where it accelerates to supersonic speeds being violently heated and pressurized before exiting the small diameter rear nozzle.
But the efficiency of this type of engine I can't find any information on and I'm unsure how much energy is needed to overcome drag on something like this at mach 1+. If it's only 5-10KW it's probably quite feasible , a 20-50KW electric motor operating the compressor is feasible, assuming at least 25% of the energy is converted into thrust.
This engine looks like it mainly uses heat and expansion to generate thrust which makes me think turning the electricity directly into heat may be more effective, but I'm even less sure how that could be done. I was thinking you could expose compressed air to a plasma arc for heating and possibly even accelerate the plasma via a magnetic stage before it exits to the final chamber. I haven't found anything useful on air breathing plasma engines, only very low thrust ones aimed for use in space.
Andrew Taylor
I mean electric heating is generally perfectly efficient, and if the air is compressed that much and slowed to a stop it may be possible to have a grid heat it up.
BUT. inst a jet intake only compressed to improve combustion efficiency? Would the same compression ratios be required with no combustion? Are there any examples of electric heating being used for propulsion?
The calculations to find how much heat is required to get the pressure you want are straight forward, you would basically compress the air into a heater then eject it through basically a rocket nozzle.
I'd like to see the calculation done to see if the idea is at all viable but I'm dealing with exams so I don't really have the time to spare.
Jose Gray
>inst a jet intake only compressed to improve combustion efficiency? Would the same compression ratios be required with no combustion? Are there any examples of electric heating being used for propulsion? Depends on the speed, at low speeds a modern turbofan needs the compressor to enable combustion but it uses that energy to drive the large ducted fan barely any thrust comes out of the turbine itself.
They have the same limitation as a remote control ducted fan plane, the turbofan can only move the air to a certain velocity, you can't spin the fan any faster because the blade tips break the sound barrier, if you add more torque nothing happens because the thrust it produces drops to zero once you're moving faster than it's maximum speed.
Turbojets work the same way as that electric jet engine, the compressor blades do not propel the air to supersonic speeds, the compression and pressure from heat expansion causes the air to reach supersonic speeds as it gets shot out of a small hole. The amount of thrust produced is much lower but the exhaust velocity is much higher. Of course the fuel gets hurled out with the hot air but provided you can efficiently heat the air you can just replace the fuel with more air.
This is how they planned to make those nuclear jet aircraft in the 1960s, the reactor just took over the job of heating the compressed air where it was normally heated via flames in a conventional turbojet.
Adrian Williams
supersonic and small sounds like its never gonna work
Grayson Collins
>Did you just decide to draw and post a picture of your penis?
