sugar rocket, combustion, rpi
10/14/20
Process learnings
Following https://www.youtube.com/watch/r2lDXoW78u0 (RIP)
recs for others
- equipment
- no need to buy sandpaper, just use concrete (or buy only a file)
- trimming fins
- tried many ways, including keeping it flat on a surface and dragging the blade, moving the coroplast instead of the plastic
- in the end: holding it like him is best strategy. dont try to cut all the way on first go; drag it across in a controlled manner first, make multiple passes, then it will cut easily
- i did it with a super flat blade
- tried many ways, including keeping it flat on a surface and dragging the blade, moving the coroplast instead of the plastic
- epoxy
- when using the tube as leverage, make sure it doesnt get epoxy on it. and to be safe, keep it loose so you can unscrew it without rotating the adapterr
- hot glue
- when gluing the attachment to the cap, make it’s high enough that it doesnt contact the edge of the pill bottle
Science learnings
- Center of gravity vs cener of pressure?
- Chemical reaction of propellant: http://people.bu.edu/straub/courses/demomaster/no3periodic.html
- An electric difference of 1 volt is when,
- 1 joule of work is needed to move 1 coulomb of charge
- if a wire results in current of 1 amp, it will dissipate 1 joule per second through the wire.
- so, does a USB of 5V mean that, when something is plugged in to complete the circuit, one end of the USB is 5V versus its own GND?
- Chemical reaction for rocket fuel: http://people.bu.edu/straub/courses/demomaster/no3periodic.html
- Rocket stability: http://www.rockets4schools.org/images/Basic.Rocket.Stability.pdf
- example of swing test https://www.youtube.com/watch?v=3S7_fg6ZCF4
- stable rocket in sim software but not IRL: https://www.apogeerockets.com/education/downloads/Newsletter220.pdf
Pi learnings
- diagram of Rpi circuitry https://superuser.com/questions/1419257/how-to-access-the-micro-sd-card-reader-on-raspberry-pi
- “flash” = put an OS on a eMMC (multimediacard): https://www.windowscentral.com/emmc-vs-ssd
- Booting Pi Zero
- Without SD card: https://github.com/raspberrypi/usbboot, https://dev.webonomic.nl/how-to-run-or-boot-raspbian-on-a-raspberry-pi-zero-without-an-sd-card
- With SD card, Headless Pi Zero setup: https://gist.github.com/gbaman/975e2db164b3ca2b51ae11e45e8fd40a, https://www.tomshardware.com/reviews/raspberry-pi-headless-setup-how-to,6028.html,
- power consumption: https://raspberry-projects.com/pi/pi-hardware/raspberry-pi-zero/raspberry-pi-zero-hardware-general-specifications#:~:text=The%20RPi%20zero%20runs%20at,processor%20runs%20at%203.3V.
- how does a booster work: https://hackaday.io/project/19035-zerophone-a-raspberry-pi-smartphone/log/69596-a-guide-on-powering-pi-zero-directly-from-liion-batteries
- run program at start: https://www.dexterindustries.com/howto/run-a-program-on-your-raspberry-pi-at-startup/
- dont put user commands in rc.local; should only be run by root https://serverfault.com/questions/422950/execute-script-from-rc-local-as-user-instead-of-root. use crontab instead
- shut down before editing it
- why doesnt
stat -x .take into account apparent size of child folders? - why is /boot the root directory of the SD card?
- “these are the only files that you can see, as this folder is in “FAT” format, which PCs can understand”: https://thepihut.com/blogs/raspberry-pi-tutorials/34243716-what-is-actually-on-your-raspberry-pi-sd-card
- ssh and wpa_supplicant.conf are removed after boot
- See failed logins:
cat /var/log/auth.log | grep -a 'Failed password' - systemctl to schedule scripts after Internet connection: https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units
- can still connect if pi is on 2.4 internet and your computer is on 5. because everything expsoed within the LAN?