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Hobby Public Radio

Your ideas, projects, opinions - podcasted.

New episodes Monday through Friday.


Brian in Ohio

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Host ID: 326

episodes: 6

hpr2714 :: Airplane stalls and Angle of Attack

Released on 2018-12-27 under a CC-BY-SA license.

stalls, a primer on why aircraft fly, and don’t fly

YouTube video of stall with narration (35 seconds)

AoA gauge from T-38 manual

Some definitions

  • chord - an imaginary line from the front of the wing to the back

  • relative wind - movement of air relative to the chord

  • angle of attack - the angle of the chord of the wing to the relative wind

  • stall - a condition where the air on the top of the wing is not flowing smoothly over the wing

  • critical angle of attack - the angle that the wing becomes stalled

  • fun - stalling and spinning and aircraft when its safe to do so

  • scary - stalling and spinning and aircraft when you don’t want to

Things not mentioned

This discussion pertained to subsonic speeds, super sonic flight introduces a whole other realm of issues.

The wings of aircraft do not stall all at once. They are designed (usually) to stall from the wing root (where the wing is attached to the fuselage) towards the tips. This ensures good roll control at slow speed and into the stall. This stalling characteristic is achieved by designing twist in the wing (washout) allowing different parts of the wing to hit the critical angle of attack at different times.

The most dangerous situation that you can find yourself in is a low altitude situation where one wing is stalled more than the other. The airplane then enters a spin. The dangerous part is the low altitude. Spins are fun, and the plane is still controllable, but you need altitude to recover. A wise man told me when turning low to the ground keep your nose down and speed up.

Most light aircraft will shudder or buffet as you approach the critical angle of attack this happens because of the disturbed airflow hitting the aircraft’s fuselage or tail. In larger aircraft no (i.e. airliners) no feel is given naturally as the plane approaches a stalled condition so systems like stick shakers vibrate the control artificially as you approach the critical angle of attack as measured by the AoA sensors. DC-9 stick shaker, a big cell phone vibrator artificial stall warning is mandatory in fly-by-wire aircraft (i.e. Airbus, f-16) as well as pure hydraulic controls (i.e. Boeing 757)

Author: Brian
Created: 2018-12-01 Sat 07:34
Emacs 25.3.1 (Org mode 8.2.10)

hpr2506 :: Build Your Own Lisp (A Book Review)

Released on 2018-03-12 under a CC-BY-SA license.

Build Your Own Lisp



  3. Daniel Holden links:

hpr2449 :: Org-mode mobile solution

Released on 2017-12-21 under a CC-BY-SA license.

brief introduction


Hi, I'm Brian in Ohio

inspiration for show

I wanted to tell a little about my trials and tribulations of finding a solution to taking org mode on the road. What's org mode? Listen to my last episode or do a duckduckgo to find out.


After switching from using a bullet journal to using emacs-org-mode as my organizing device I immediately saw that lugging a laptop everywhere was not going to work for me. I wanted to be able to access org-mode, especially the agenda view, anywhere I might be. Laptops with limited battery life and a large physical presence were not going to work for me.

mobile-org app

The first solution I tried, and the most obvious, was the mobile-org app. Its available for android or ios. I can only attest to the android version. Its an easy from the play store. This solution didn't work for me for a number of reasons. First, the documentation for the setup is terrible, and I became frustrated by the workflow and could not get useful results using the app. Mobile-org seems to be built around using dropox. In order to get around that I tried various methods of syncing my org files using onboard storage. Seeing this wasn't going to work I bit the bullet setup a dropbox account installed the clients, one on my slackware laptop and the other on my phone only to find dropbox doesn't support this application anymore. A little digging around and it seems the API used by mobile-org isn't up to snuff any more so, fail. I cut my loses and moved on to another possible solution.


My next crack at solving the portable org mode problem was getting a pitop laptop Pitop is a laptop based on a raspberrypi. I won't go into the details of the device here but I'll say my idea for using this device was its advertised 8+ hour battery life. My old linux laptops rarely give me 2 hours of life So even though the pitop was physically larger than I wanted I gave it a whirl. Lets just say the battery does last 8+ hours, it just can't survive many recharges. 2 battery packs later I gave up on the pitop and went looking for something else.


I heard klaatu mention a device called a pocketchip on his gnuworld order podcast I looked into it and here I thought might be a device that could work. Pocketchip is a handheld linux computer. After ordering the device I began setting it up for my use case. There are plenty of tutorials on the pocketchip website on how to extend the usefulness of this product. The size of the device was good and the battery life was ok. Some people complain about the chicklet keyboard but I actually did not mind it to much. It took some fiddling to get the emacs keybindings I use to work on the odd keyboard layout, but its a linux computer so there's plenty of information out there. I used a thumb drive as a repository for my org files, wrote a couple of scripts to sync up the files with whatever device the drive was plugged into and wala a mobile org solution! Alas, the pocketchips demise was its build quality. The heart of the pocketchip, the system board's usb mini plug fell off, and then one system tweak later I bricked the device. I'll recover it eventually, you can program it through the gpio pins, but this was a quest for portable-org-mode, not fixing pocketchips, so onward.

raspberry pi tablet

I saw a build of a raspberry pi tablet that looked very nice Always up for a challenge, I cobbled together a prototype and tried it out. The reason I eventually dropped this solution because the virtual keyboard didn't work well and I couldn't get the official raspberrypi lcd to rotate from portrait to landscape dynamically. Still a fun project and I'll get some use out of it sometime.

android phone

Well here's the solution I came up with. I was searching around on the internet and found a link telling about running emacs on an android phone. It involves installing the termux app, the hackers keyboard, both available in the google play store and apt-get installing emacs on the phone. After that I had full emacs running, all be it in a terminal so its slightly different then running on the desktop, and with emacs you get, drum roll please, org-mode. With this i have the device I always take with running org-mode. I sink my org files between my laptop and phone using the afore mentioned drop box account. The hackers keyboard works flawlessly and can digest any emacs keybinding I need. I also have a logitech bluetoothkeyboard that I can use if I have a lot of typing to do in org-mode on my phone, such as these shownotes!


I find org-mode so useful that I want it available any where I go. And over the course of the last 8 months I went on a journey trying to find a solution to that desire. In the end, the solution was pretty obvious, these portable computers we carry around are amazing and thanks to the developers of termux and the hackers keyboard my phone is now infinitely more useful to me. Thanks for listening.

hpr2415 :: bullet journal to org mode

Released on 2017-11-03 under a CC-BY-SA license.

1 Brief introduction

1.1 Myself

Hi, I'm Brian in Ohio

1.2 Inspiration for show

I heard Shane Shennan on episode 2299 doing a what's in my bag episode where he briefly mentions using a bullet journal. Then I think I heard Ken Fallon wondering about bullet journals on community news for the month with that episode. So I thought a show was in order explaining how I went from using a bullet journal to using emacs org mode.

1.3 Parameters

I'm not an expert on any of the following topics: bullet journal, Getting things done (GTD), orgmode or emacs. I'm someone who has tried these tools, climbed the learning curve and have some observations to make through that process.

2 What's a bullet journal

2.1 Created by ryder carrol

The analog system for the digital age

2.2 Where I found out about it

2.3 What it is

Method of laying out a notebook and using it to organize and process ideas and tasks. I won't try to explain exactly how it is set up. The video tutorial is excellent. You can use any notebook and divide it up into index pages, future log, monthly log and daily log there's a visual indexing/ tagging system to help organize stuff. Its extremely customizable.

2.4 How I used it

I bullet journaled for 2 and a half years, initially set it up stock but later put the index at the back. I used it as a daily planner, idea storing device and short term and long term goal setting tool.

2.5 Strengths

Customizable but within framework, gives a method to get organized that you can tailor to your needs. Its pretty easy to find needed info, if you're diciplined about using. It its battery free

2.6 Shortcomings

Need to be disciplined. Can be tedious to enter items in month, daily and index sections. It takes time to set up. I think Shane's use case he mentioned in podcast as sort of a project/idea book sounds pretty cool and might be a really good use case for this system. Hard to edit, this may be a strength for some people, but for me as a daily planner it was a little daunting to use. Adding stuff to something requires either leaving space ahead of time or indexing to a new page. The monthly log was always a mystery to me on how to use it. If you lose it you've lost it, no easy way to back it up

3 What is org mode

3.1 Created by Carsten Dominik

3.2 what it is

Is an editing and organizing mode for notes, planning, and authoring in the free software text editor Emacs.

3.3 How I found out about it

3.3.1 emacs Wanted a commandline C development environment for microcontroller project development IDE

Worked with vim/ a bash shell as a sort of minimal IDE. I specifically was using it on a laptop that didn't have X installed on it. Just for fun, not my bread and butter. Wanted to try something new

Knew about emacs, had tried it didn't like it Thanks to klaatu for emacs hpr emacs episodes Thanks to youtube found out about org mode

Rainer Konig - getting yourself organized with org-mode

3.3.2 Switched in october 2016

3.4 How I use it

At its heart an org-mode is an outliner. I use org-mode to set up daily todo tasks, organize projects, jot down notes. Org-mode has a subsystem call agenda view that can generate daily planner views from your org-mode files. I initially tried to mimic the bullet journal in org-mode, but found that it was better to approach org mode relying on its strengths, which are different, as you can imagine, from a Bullet journal.

3.5 Strengths

I like it because its editable, searchable and customizable. Projects can be broken down into as fine a detail as you want and that detail level can expand or contract as necessary. The power of org-mode comes out when you use it to capturing ideas, tasks and information. Capturing these events is done via capture templates that you can create. This new data is then saved to the appropriate org file then shows up in your agenda view. Its extremely easy to back up, it's text based and therefore future proof. There are many good tutorials and resources online

3.6 Shortcomings

Need to know a little about emacs and that can feel overwhelming to try. This new tool will require you to use your brain. Emacs keybindings

4 What's next

Trying to find a good way to use orgmode portably. mobile-org app for android doesn't work for me. This has led to trying a couple of different solutions which I will record other hpr episodes about. Thanks for listening. If you have ideas on Bullet Journals or Org-mode I'd love to hear an episode about it. I'll put links into the show notes, this is Brian in Ohio signing off.

hpr2158 :: Art Club

Released on 2016-11-09 under a CC-BY-SA license.

hpr1988 :: Linux from Scratch

Released on 2016-03-16 under a CC-BY-SA license.

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