Deep space fundamental research is IMO a reasonable activity for NASA. Building launchers, lofting payloads and people, etc. is not. The private sector (real private companies, not the likes of Boeing and Northrop Grumman) are proven to be much more efficient at that.
Starlink is more than fast enough to provide streaming video, so such operators now see the writing on the wall. Clarke orbit internet providers such as Hughes are especially threatened.
T is thrust in Newtons
P is power of motor in Watts
η is propeller efficiency, 1 is perfect
Η is motor efficiency, 1 is perfect
d is propeller diameter in meters
ρ is air density in kg/m³
Known numbers:
P = 350 W, or 175 W per rotor (a simplification, but close enough)
d = 1.2 m
ρ = 0.013 kg/m³ at Mars' surface
Using typical efficiencies for propellers and motors:
η = 0.75
Η = 0.9
Mass of helicopter in Mars' gravity is 0.68 kg.
Using these numbers for one rotor:
T = ³√(30625 ✕ 0.56 ✕ 0.81 ✕ 3.14 ✕ 0.72 ✕ 0.013) ≈ 7.4 N
7.4 N is around 0.75 kg of thrust for a single rotor - more than the helicopter's weight on Mars. So with both rotors it'll have more than enough thrust to fly there.
Its operational orbit was ~800 km. At that altitude debris will be up there for quite a few years (depending on the ballistic coefficients of the fragments).
The old NOAA satellites are pretty cool as their signals are easy to receive and decode.
dominus_stercae 0 points 4 years ago
Congrats! I'm envious - looking forward to ditching my cable provider.
/v/technology viewpost?postid=6083700204381
dominus_stercae 0 points 4 years ago
Love the dust lanes. On that note: at dark sites one can see the dust lanes of our own galaxy with the naked eye.
/v/Space viewpost?postid=607e59b1e345b
dominus_stercae 0 points 4 years ago
Deep space fundamental research is IMO a reasonable activity for NASA. Building launchers, lofting payloads and people, etc. is not. The private sector (real private companies, not the likes of Boeing and Northrop Grumman) are proven to be much more efficient at that.
/v/spaceflight viewpost?postid=607d8b184b7d0
dominus_stercae 0 points 4 years ago
Starlink is more than fast enough to provide streaming video, so such operators now see the writing on the wall. Clarke orbit internet providers such as Hughes are especially threatened.
/v/technology viewpost?postid=606fcbd7e93ef
dominus_stercae 0 points 4 years ago
5000 tons is akin to the weight of a small ship.
/v/Space viewpost?postid=606fcdaf08af5
dominus_stercae 0 points 4 years ago*
Can you provide some calculation supporting your assertion?
ETA: Here's a thrust calculation for this case.
Static propeller thrust T = ³√(P² ✕ η² ✕ Η² ✕ π ✕ (d²/2) ✕ ρ)
Where:
T is thrust in Newtons
P is power of motor in Watts
η is propeller efficiency, 1 is perfect
Η is motor efficiency, 1 is perfect
d is propeller diameter in meters
ρ is air density in kg/m³
Known numbers:
P = 350 W, or 175 W per rotor (a simplification, but close enough)
d = 1.2 m
ρ = 0.013 kg/m³ at Mars' surface
Using typical efficiencies for propellers and motors:
η = 0.75
Η = 0.9
Mass of helicopter in Mars' gravity is 0.68 kg.
Using these numbers for one rotor:
T = ³√(30625 ✕ 0.56 ✕ 0.81 ✕ 3.14 ✕ 0.72 ✕ 0.013) ≈ 7.4 N
7.4 N is around 0.75 kg of thrust for a single rotor - more than the helicopter's weight on Mars. So with both rotors it'll have more than enough thrust to fly there.
/v/spaceflight viewpost?postid=606f0405bd64d
dominus_stercae 0 points 4.1 years ago*
Its operational orbit was ~800 km. At that altitude debris will be up there for quite a few years (depending on the ballistic coefficients of the fragments).
The old NOAA satellites are pretty cool as their signals are easy to receive and decode.
/v/Space viewpost?postid=6057f0c4b3445
dominus_stercae 0 points 4.1 years ago
Given the numbers Musk is proposing, that might not be too far from truth.
/v/spaceflight viewpost?postid=6054182558a99
dominus_stercae 0 points 4.2 years ago
Rendering of the proposed booster next to Electron:
https://techcrunch.com/wp-content/uploads/2021/03/Electron-Neutron-e1614601323411.jpg
/v/spaceflight viewpost?postid=603d04d701ec0