patrickjp93 wrote:kalvado wrote:patrickjp93 wrote:Doppler is kid's play and is used to check density of weather systems. It's looking at resonant modes of light, not the turnaround time from particles a known distance away.
Special Relativity is the enveloping theory (and long since tested and proven) around how light interacts with objects in moving reference frames. The best way to understand how it is applied here is probably using the light speed train tunnel paradox. Because the speed of light does not change in a given set of conditions (in this case an air body's elemental composition and pressure) regardless of how fast its source is, you can use the difference in time for light to bounce back from a known distance to get your speed.
If you're running and throw a ball in front of you, the speed/velocity of the ball increases in the line you're traveling on above your running speed. However, this breaks down at the speed of light where it is impossible to exceed that speed. You running forward with a laser pointer in hand does not increase the propagation speed of the laser. Therefore, any change in time for a particle to leave the pointer and collide with what's in front of you and return which exceeds this absolute speed limit is your speed going in the opposite direction. That's why Special Relativity and Lidar can be used for this. Even radar can, but because it relies on some oscillatory modes to not come back as pure noise, it's probably easier to make such a system with Lidar.
OK. Just to make it clear - my PhD is in physics. And I know relativity a bit.
For the plane traveling at 3e2 m/s = 1e-6 c special relativity effects are in the noise. Lidar doesn't use relativistic effects.
So, try again.
I'm afraid Boeing (and a basic textbook) disagree with you, as they'll be using Lidar to detect turbulent flow up to 10 miles away, and the only way you can do that is detect multiple velocities of air streams simultaneously. https://www.aviationtoday.com/2018/03/2 ... onstrator/
You can claim to have a PhD, but that doesn't matter to me. Let's see you prove the argument rather than rest on your laurels.
You never mentioned clear air turbulence before. Turbulence is irrelevant to the converation anyway. We started with airspeed measurements, and somehow you were bringing special relativity into it.
Could you please elaborate on that part of converation?
Just to remind you:
patrickjp93 wrote:mwananchi wrote:patrickjp93 wrote:And you don't need the AoA to get your air speed. Using triangulation from the radar sensors or Boeing's upcoming Lidar implementation, you can derive craft speed based on the bounce time of reflected beams at a given distance ahead since Special Relativity is a well-understood scheme at this point.
Take the case of over-water flights: whether radar would provide actual craft speed readings is probably a question for the forum experts to chew over.
Lidar at high altitude over water for speed measurement purposes sounds like quite an advanced application too.
Special relativity doesn't give a damn about being overwater, or did you forget we have overseas satellites. You can use light's deflection off the air and the time it takes to receive the reflection, because the speed of light is constant regardless of its emitter having non-zero speed.