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| bio | website | ericmenze.com |
|---|---|---|
| location | Minneapolis, MN | |
| age | 28 | |
| visits | member for | 1 year, 1 month |
| seen | 23 hours ago | |
| stats | profile views | 92 |
I'm a Computer (Web) Programmer/Analyst based in Anchorage, AK and Minneapolis, MN. I use (among other things) ASP.NET, C# and SQL Server.
I build things. Bicycles, computers, websites, guitars, cars, motorcycles, sound sytems... lots of things.
- Resume: http://ericmenze.com
- Personal Website: http://ehryk.com
- Pause your videos at specific locations: http://pauseforlater.com
- Calculate and build spoked bicycle wheels: http://wheelspoking.com
- See activity specific analysis of your GPX Files: http://gpxdataanalyzer.com
- Tool to open command/powershell prompts from any location (Windows): https://github.com/Ehryk/ContextMenuTools
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Sep 14 |
comment |
Lever Mechanics - How to formulate an ideal lever launch For efficiency, should $E_{in}$ be ${PE}_{weight}$ or ${PE}_{system}$? (as in, factoring the weight of the projectile into the equation or not) |
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Sep 14 |
revised |
Lever Mechanics - How to formulate an ideal lever launch Updated PE_system formula to include starting position of m_projectile |
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Sep 14 |
revised |
Lever Mechanics - How to formulate an ideal lever launch Updated PE_system formula to include starting position of m_projectile |
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Sep 14 |
asked | Lever Mechanics - How to formulate an ideal lever launch |
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Sep 14 |
answered | Lever Mechanics - How to formulate an ideal lever launch |
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Sep 13 |
revised |
Could we make a trebuchet that could launch objects to a stable orbit? Added quicklaunch reference. |
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Sep 13 |
revised |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? Clarified what m_2 was |
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Sep 13 |
comment |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? Yes, sorry. I didn't want to repeat $m_0$ and $m_1$. |
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Sep 13 |
comment |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? It should also be noted that $v_e$, by contrast, will exponentially relieve fuel requirements ($m_p = 1 - e^{-\frac{\Delta V}{e_v}}$. If we could accelerate the exhaust to 300 km/s instead of just 4.5 km/s (1% of c), then it would only take 3% of $m_0$ to get from the surface to LEO. |
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Sep 13 |
comment |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? Completely agreed, which is why I used the word 'ease' - it backs the percentage of fuel requirement down by some non-trivial amount, but it's still a large percentage of your starting mass. |
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Sep 13 |
revised |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? Corrected mass of the propellant from LEO -> GEO |
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Sep 13 |
comment |
Calculation of Distance from measured Acceleration vs Time The model rocket will experience some amount of 'tipping' and may even reverse direction on descent, which will skew your measurements by providing smaller z accelerations than accurate, and then by adding to the position when falling, respectively. On a ground based vehicle x and y might be useful, but once you introduce suspension it really needs a gyroscope to track the roll, pitch, and yaw of the accelerometer to have much accuracy. |
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Sep 13 |
revised |
Calculation of Distance from measured Acceleration vs Time Added sample excel contents |
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Sep 13 |
answered | Calculation of Distance from measured Acceleration vs Time |
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Sep 13 |
revised |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? Fixed initial fuel mass to launch mass |
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Sep 13 |
comment |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? Out of curiosity, why did you use the Nabla $(\nabla)$ symbol? Is difference in gravitational potential energy a mathematical gradient, divergence, or curl, as mentioned in the wikipedia article on the symbol? Or did you just pick it not following a convention? |
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Sep 13 |
answered | Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? |
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Sep 13 |
comment |
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO? Thanks, your answer rocks. It should be noted that Space Guns or other forms of non-rocket space launches, including ion drives and the mechanism being planned by QuickLaunch, Inc. would all be, at least for some of their trajectory, fixed mass - so the calculation isn't completely irrelevant. I do feel I hijacked the question because of the interestingness of your fixed mass comment. |
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Sep 13 |
comment |
What is the most efficient machine for translating gravitational potential energy of one mass into kinetic energy of a different mass? $$E_{in} = m_{weight}*g*h = 9.8*100*100 = 98000J$$, I didn't have room to include it above. |
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Sep 13 |
comment |
What is the most efficient machine for translating gravitational potential energy of one mass into kinetic energy of a different mass? Let's take a system with an inelastic band, frictionless pulley, and no air resistance, sample problem above with a 100kg weight. The Force on the large weight side would be $F=m_{weight}*g$ and with the projectile side $$F=m_{projectile}*g$$. Now let's let the mass drop 100m. The total $$P_e = m_{weight}*g*h - m_{projectile}*g*h = 100*100*g - 10*100*g = 9000*g = 88200J$$ Now, this force gets the system moving $$K_e = 1/2*m_{system}*v^2 = 1/2*110*v^2$$ so $v=40m/s$. The energy now in the projectile is $K_e = 1/2*m_{projectile}*v^2 = 8000J$. $$Efficiency = E_{out}/E_{in} = 8000J/98000J = 8\%$$ |
