Techrants.Random

Posted on Fri 10 August 2018 in Tech

28/05/2019

• I got to know about this Spacecraft Simulation Game called 'Orbiter 2016' through one of the questions from Space Stack Exchange which felt like a good free alternative to Kerbal Space Program. I downloaded the game and installed it. Initially I tried to read through the menu and documentation but the interface was so unintuitive that I had to uninstall it. May be some other time.

21/05/2019

• Running NASA's EngineSim Java Applet in your browser - None of the offline method worked because the browser kept on blocking the Java applet from running. Only way to add the URL to site exception list was to upload the extracted folder online and that's what I did. If you want to play around, add https://mechanicalcoder.github.io/EngineSim/EngineSim.html to Java site exception list (go to Program > Java > Security > Edit Site List > Add). Open the same in Internet Explorer. Happy playing!

15/05/2019

• Understanding wave-based attitude control of spacecraft with fuel sloshing dynamics - https://www.degruyter.com/downloadpdf/j/meceng.2016.63.issue-2/meceng-2016-0015/meceng-2016-0015.pdf

25/04/2019

• Reading about Expander Cycle Rocket engine after one of Scott Manley's videos - https://blogs.nasa.gov/J2X/2014/03/24/inside-the-leo-doghouse-the-art-of-expander-cycle-engines/

28/03/2019

• I had recently installed MATLAB 2018b on my system. It's been taking a lot of time to start (somewhere in the range of 8 to 10 minutes). I looked for the solution online multiple times but still couldn't resolve it, although I did identify that it had something to do with my license file. It would open instantly if I ran this command -
>> cd %path_to_MATLAB_directory%


After reading further today, I found out that I could measure the time taken by each process during initialization through the following command -

>> matlab -timing


Though, I could see that 'desktop init' took the most time, I couldn't find any viable solution related to it except disabling all other programs while starting MATLAB (which isn't necessarily a solution btw). Finally, I read that if I have multiple license files in my licenses folder, MATLAB might be getting confused. So, I removed the other two license files elsewhere and voila! it worked.

26/03/2019

• While browsing Quora for careers in Aerospace Engineering, I came to know these two control systems in one of the answers -
• Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of the flight controls are converted to electronic signals transmitted by wires (hence the fly-by-wire term), and flight control computers determine how to move the actuators at each control surface to provide the ordered response. It can use mechanical flight control backup systems (Boeing 777) or use fully fly-by-wire controls

• A glass cockpit is an aircraft cockpit that features electronic (digital) flight instrument displays, typically large LCP screens, rather than the traditional style of analog dials and gauges.

23/03/2019

• Though I wrote about MathJax issue previously on my blog, I didn't include any mathematical expression to validate. How silly! So here it is, a formula for measuring apparent magnitude of a star with respect to a reference -

$$m_{1} - m_{ref} = -2.5log_{10}{\frac{I}{I_{ref}}}$$

• Apparent magnitude (m) and absolute magnitude (M) are related as

$$m - M = 5(log_{10}d-1)$$
where d = distance to the star measured in parsecs

22/03/2019

• Measuring brightness of a celestial object is an important concept in astronomy. It is usually denoted in terms of 'Magnitude' (apparent or absolute magnitude). The scale is logarithmic and defined such that each step of one magnitude changes the brightness by a factor of the fifth root of 100, or approximately 2.512. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. Read more - https://en.wikipedia.org/wiki/Magnitude_(astronomy)

13/03/2019

• One of the most talked about rocket upper stages, Centaur - https://en.wikipedia.org/wiki/Centaur_(rocket_stage)

• Also this - https://historicspacecraft.com/Rockets_Upper_Stage.html

11/03/2019

• I started learning orbital mechanics seriously - http://www.braeunig.us/space/orbmech.htm

07/03/2019

• Rocket engines and thrusters are largely talked about in terms of specific impulse. Although, I could deduce its scientific meaning in terms of physical parameters, I was still unsure how it translates to engine performance and more so why is it used as defining parameter - https://en.wikipedia.org/wiki/Specific_impulse

06/03/2019

• I was looking into ISS communication medium and somehow I landed at an article that talked about HAM community around the world for amateur radio operators. People have been able to talk to astronauts through HAM as well - https://www.thebetterindia.com/70447/ham-amateur-radio-operators-india/

• I went through several resources trying to find out the norms/rules/regulations that exists or permissions we need to obtain prior to launching an amateur rocket in India. I could hardly find any except some college organization and one company that organizes workshop on model rocketry. I did find one paper about 'High Altitude Balloon Experiments' from Indian Institute of Astrophysics which outlines some of the answers I needed - https://arxiv.org/ftp/arxiv/papers/1506/1506.01538.pdf

04/03/2019

• I played with face-detection JavaScript API face-api.js. I'm reading further on it. Will upload the project on the net through Heroku as PaaS.

02/03/2019

• Did you catch the DM-1 launch? - https://www.youtube.com/watch?v=2ZL0tbOZYhE

• Found this fantastic resource for 3D models from NASA - https://nasa3d.arc.nasa.gov/

01/03/2019

• Rocket Motor Classification - https://en.wikipedia.org/wiki/Model_rocket_motor_classification
• The designation for a specific motor looks like C6-3. In this example, the letter (C) represents the total impulse range of the motor, the number (6) before the dash represents the average thrust in newtons (4.448 N per Lb.), and the number (3) after the dash represents the delay in seconds from propelling charge burnout to the firing of the ejection charge (a gas generator composition, usually black powder, designed to deploy the recovery system). A C6-3 motor would have between 5.01 and 10 N·s of impulse, produce 6 N average thrust, and fire an ejection charge 3 seconds after burnout.

28/02/2019

• Read this great article by Deepana Gandhi on working with Team Indus. Found this technical resource from NASA they got a lot of help from, to prepare their design - https://www.sti.nasa.gov/

------------------------Hiatus due to moving to Delhi for my internship-----------------------------

10/02/2019

• I learned R for the first time. This Medium article helped me a lot to get started - https://towardsdatascience.com/a-guide-to-data-visualisation-in-r-for-beginners-ef6d41a34174. Though there were some glitches, I quickly solved them through little bit of searching. I have mentioned my remarks in the comment of that article.

09/02/2019

• Hopped over to Tom Stanton's Twitter where he mentioned about this unit 'awg' I haven't heard of. It's an American Wire Gauge standards for electrically conducting wire diameter - https://en.wikipedia.org/wiki/American_wire_gauge

31/01/2019

• Read SpaceX's recent FCC filing for Falcon Heavy flight - https://fcc.report/ELS/Space-Exploration-Technologies-Corp-SpaceX/0028-EX-ST-2019

• Visiting my sister here in Patna, I visited the factory where they carry out purification of nitric acid. Finding out density vs. temperature chart for solubility of the same in water - http://www.handymath.com/cgi-bin/nitrictble2.cgi?submit=Entry

23/01/2019

• Watching 'Sixty Symbols' video on YouTube about Mach's Principle brought me here - https://en.wikipedia.org/wiki/Mach%27s_principle

Actually, it was one of the major influences to Einstein's General Theory of Relativity

10/01/2019

• I came to know about Norbert Weiner while watching the introduction lecture by Prof. Amar G. Bose on Acoustics. Link - https://teachingexcellence.mit.edu/inspiring-teachers/amar-bose-6-312-lecture-01-introduction

• Reading Falcon 9 user guide by SpaceX. Learning about staged combustion and gas generator cycle rocket engine - https://en.wikipedia.org/wiki/Staged_combustion_cycle In addition to the propellant turbopumps, staged combustion engines often require smaller boost pumps so to prevent both preburner backflow and turbopump cavitation. For example, the RD-180 and RS-25 use boost pumps driven by tap-off and expander cycles, as well as pressurized tanks, to incrementally increase propellant pressure prior to entering the preburner.

The ultimate performance of a rocket engine is primarily limited by the ability of the construction materials to withstand the extreme temperatures of rocket combustion processes, as a higher temperature directly increases the local speed of sound that limits exhaust velocity - Gas generator cycle