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cross-posted from: https://sopuli.xyz/post/46361958
Instead of navigating airport parking, shuttles and terminals, passengers would use those “ultra short access points,” rooftops, piers, open clearings, even soccer fields. The company said the aircraft could also serve general aviation airports, which tend to be closer to where people actually live.
The target range is 50 to 250 miles — think D.C. to Richmond, or D.C. to Blacksburg, Virginia, where Virginia Tech is located. Those trips currently take up to four hours by car.
According to the market study, there are 6,249 routes across the country where more than 1,000 people travel every day in that distance range. Right now, only 1% of those trips go by air, and 85% of those routes have no air service within 40 miles of where travelers start or end their journey, the report said.
I don't think electric aviation makes sense as a long distance thing yet in terms of weight vs. distance/energy density but Blown Lift short-medium distance aircraft are a perfect match for the current practical limitations of electric flight. The major advantage of electric aviation however is the massively reduced carbon footprint.
"Blown Lift" is the reason that aircraft like these have so many tiny propellers, the process of blowing air over the wings increases lift performance of the wing especially at lower speeds for a given aerodynamic design. Wikipedia will only talk about applications in jet engines but a propeller can do it just as well.
A comprehensive experimental study on aerodynamic lift and moment performance on a blown wing configuration has been presented. The design of experiment allows for easy modification of configuration parameters : flap deflection, propeller install angle and vertical position. Separate balance measurements allows for comparison of propeller augmentation effects based on measured thrust condition.
A new set of augmented aerodynamic coefficients is defined for comparison of propeller wake effects at different freestream and thrust conditions. Lift augmentation effect is thus related to a wake energy ratio. The results revealed significant lift augmentation for a lifting surface. The effect is angle of attack dependent. At lower angle of attack, circulation induced lift component appears to be constant for high wake energy ratio, whereas this component becomes variable at higher angle of attack. Negative propeller install angle or higher propeller positions tend to slightly increase this augmentation effect, although mounting the propeller too high (≈ 0.2Dp) may cause wing surface move out of propeller wake. Augmentation in pitch moment was also observed. At low angle of attack, propeller wake effect only amplifies zero-lift pitch moment through thrust loading. At higher angle of attack, there exists a critical wake energy ratio, below which the propeller wake can no longer augment wing pitch moment. Propeller install angle and vertical position don’t appear to have a significant influence on wing pitch moment, although the offset of propeller thrust line may create additional pitch moment.
Figure 8 To better understand the analysis, a set of measurement at V∞ = 5m/s is plotted in Fig. 8. The solid line represents lift coefficients obtained without propeller assembly and with flap at neutral position. For the symmetrical airfoil used during test, CL is null at zero angle of attack and it reaches a maximum of 0.6 at around α = 50◦ in post-stall region. Due to the large interval between measured α, stall region cannot be observed. When the flap is deflected by 30◦, the measured lift coefficient follows the dashed line. Deflection of flap increases positive camber, and thus CL at α = 0 is increased by 0.6. Maximum CL reaches to a higher value of 0.8 in post-stall region. The blue shaded area between two curves represents the effect of flap on lift coefficient ∆CL,δf .
If propeller assembly is installed and is running at 5000RP M , the measured CL on the wing surface is further increased. The effect of propeller is represented by the orange shaded area ∆CL,prop. This variation in lift coefficient is based on an already established 30◦ flap deflection, and thus is purely propeller effect on the wing surface, whereas the combined area of orange and blue region contains both the effect of aerodynamic profile (δf ), and the effect of propeller wake. As mentioned before, only propeller wake effect is analysed in the current study, hence the variation represented by the orange shade in Fig. 8.
https://enac.hal.science/hal-02550198
To understand why we are seeing a proliferation of designs like this now you have to consider the inherent design tradeoffs with fossil fuel engines where each point that you convert fossil fuel into mechanical energy is in a sense a separate entire system. It is basic common sense that in general the more smaller fossil fuel engines you use (rather than an equivalent power rating accomplished with fewer larger engines) the more inefficiencies of scaling a system down enter into the equation.
Electric engines I am sure in a physics sense don't negate this basic property of things that do work (in the physics sense) but they do make the penalty far less severe. Think about the nightmare of maintaining 12 different fossil fuel engines vs 2 fossil fuel engines and then think about the jump between maintaining 12 electric engines vs 2 electric engines and you can see the point. As a result expect so see an explosion of short and midrange Short Takeoff And Landing Vehicles.
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I graduated from my bachelors in December, and I'm feeling burnt-out about job hunting. This is a project I wrote during my degree, in my spare time, to try out some ideas from my lectures and to learn OpenGL.
I took this screenshot while I was testing out monochromatic lighting. The ships are rotating clockwise.
I found it interesting that the receding ships bunch more closely together, that really convinced me that I had it working right.
The code is on GitHub jarrydac/gl_relativity. It's quite rough.
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Adularescence is an optical phenomenon that is produced in gemstones like moonstone. It is best described as a milky, bluish luster or glow originating from below the surface of the gemstone. The luster, appearing to move as the gemstone is turned or as the light source is moved, gives the impression of moonlight floating on water. It is most typically produced in adularia, an orthoclase. This photograph shows adularescence in a moonstone cabochon from Minas Gerais, Brazil.
Photographer: Didier Descouens
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cross-posted from: https://lemmy.world/post/45992308
This is a map of the universe. The Dark Energy Spectroscopic Instrument (DESI) at Kitt Peak National Observatory, Arizona, has finished its five-year survey. It observed more than 47 million galaxies and quasars and created a 3D map centered on the Earth. Today's featured image shows a thin slice of these data: the black gaps indicate where our Galaxy obscures distant objects. The feathery web in the inset shows the large scale structure of the universe. Light of the most distant galaxies shown here travelled for 11 billion years to reach the Earth. Galaxies cluster throughout cosmic history under the competing influences of gravity and dark energy, responsible for the accelerated expansion of the universe. Analysis of early DESI results hinted at the possibility that dark energy, described as a cosmological constant by Albert Einstein, may not be constant after all. But we still have to wait for the analysis of the now complete dataset. The nature of dark energy is the biggest mystery of cosmology.
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