A World War 2 training video for evading flak cannon fire is one of the best examples of graphical information presentation that I've seen. https://www.youtube.com/watch?v=qP_-WUMi-nw
It features smoothly animated and highly functional designs as well as overlaying graphics on real footage to achieve a fashion of "augmented reality". The production quality is astounding and it is amazing to think that it was produced in the 40s. The entire video is an inspiring example of conveying information.
That was really interesting. I never knew there was this kind of strategy behind flak evasion. Man, must have taken some stones to do a bomber mission. I knew an old timer that flew bombers in WW2 and he said towards the end of the war the germans were running out of metal and all sorts of things were used as flak. He said nuts and bolts were pretty common. He'd find them embedded inside the cabin after close flak fire. Pretty scary to think that your end might come from a washer.
The wiki article gives good explanation of how bombing developed during WWII - starting as a weapon to terrible to be used (based on poor quality data); with general agreements not to kill civilians; realising that bombers were hopelessly inaccurate; changing tactics to allow bombing of civillian populations, including the (to my mind) war crimes of fire bombing.
> Bomber Command crews also suffered an extremely high casualty rate: 55,573 killed out of a total of 125,000 aircrew (a 44.4% death rate), a further 8,403 were wounded in action and 9,838 became prisoners of war.
We know. I put a link to that video (to the Internet Archive, not YouTube) on Wikipedia years ago.
There's a whole series of Chevrolet films from the Jam Handy organization at the Internet Archive. "Take it Easy", "Spring Harmony" and "Shockproof" cover how auto suspensions work. "Facts on Friction", "Hydraulics" and "What stops them" explain brakes. "Head on" and "No Ghosts" - auto frames. "Water Boy" - cooling. "Free Air" - carburetor. There's more.
If you like videos like this, check out Retrotechtacular on Hackaday. They have a series on mechanical firing computers on navy ship that is nothing short of mech-eng porn, and I mean the classy kind.
Nice to follow that with this short video illustrating how one type of locking differential works to eliminate some of the disadvantages of an open differential.
So, one wheel starts spinning, and then, at a certain speed, it gets immediately locked into the other wheel which isn't moving at all? How does that not blow up the entire differential?
For manually operated lockers the axle shafts have to be moving at the same speed or with very little difference in speed to be engaged.
>Only engage the Eaton ELocker™ differential while the vehicle is stationary or operating at speeds of 3 mph
or less with minimal wheel slippage.
This specific locker (Eaton G80) is self-engaging up to a set speed which is intended to prevent this from happening, though it has been known to occur.
>The G80 can be very effective when used within its limitations. However its very design can lead it to failure. It requires a certain amount of speed difference between both rear wheels to operate. Basically more slip than you would ever encounter going around a turn, but it will not lock at speeds above roughly 20-30mph. This it where it earned the name "gov-lock". It has a speed governor that operates off centrifugal force inside to govern locking.
When it locks, it locks hard. Imagine one tire sitting still, and suddenly being launched to a speed of 20-25mph. That takes a great deal of force and puts a lot of strain on internals. They have a tendency to break with no warning.
With a hard-locking differential ("lockers", generally used off-road), engagement while one wheel is spinning is ill-advised. They're generally toggled on at low/zero speed by the operator in anticipation of a traction-loss situation.
Yup. And they typically have to be unlocked when not needed as it is almost impossible to turn with the rears locked. However, with pneumatic or electrical operation from the driver's seat this is pretty convenient.
The type of locker I'm more familiar with takes a different approach: the rear end is locked by default but unlocks when it needs to. e.g., going around a turn causes the outside tire to turn faster than the inside one, and the teeth in the locker are angled so the speed difference causes them to cam out and decouples one axle shaft from the diff, letting it spin independently while the inner axle shaft is under power.
I had that system in my Toyota pickup and even in 2WD, it was absolutely unstoppable offroad.
Wow, that was a fantastic video. I could understand it easily only because they iteratively added complexity to the models. It's amazing how well they have made the tutorial for the layman.
I remember seeing this a while back and realizing I learned more from this video than I learned in class during my college course. Amazing production value. We should properly catalog such gems so that students and even professors can use these to teach (instead of attempting to reinvent the wheel)
I use this video quite often to show an example of one of the best educational videos I have ever seen. The language, presentation, use of graphics (impressive for the time) and demonstrations is just superb.
58 comments
[ 4.6 ms ] story [ 124 ms ] threadIt features smoothly animated and highly functional designs as well as overlaying graphics on real footage to achieve a fashion of "augmented reality". The production quality is astounding and it is amazing to think that it was produced in the 40s. The entire video is an inspiring example of conveying information.
http://en.m.wikipedia.org/wiki/RAF_Bomber_Command
The wiki article gives good explanation of how bombing developed during WWII - starting as a weapon to terrible to be used (based on poor quality data); with general agreements not to kill civilians; realising that bombers were hopelessly inaccurate; changing tactics to allow bombing of civillian populations, including the (to my mind) war crimes of fire bombing.
> Bomber Command crews also suffered an extremely high casualty rate: 55,573 killed out of a total of 125,000 aircrew (a 44.4% death rate), a further 8,403 were wounded in action and 9,838 became prisoners of war.
That's pretty much "toss a coin".
There's a whole series of Chevrolet films from the Jam Handy organization at the Internet Archive. "Take it Easy", "Spring Harmony" and "Shockproof" cover how auto suspensions work. "Facts on Friction", "Hydraulics" and "What stops them" explain brakes. "Head on" and "No Ghosts" - auto frames. "Water Boy" - cooling. "Free Air" - carburetor. There's more.
https://archive.org/search.php?query=creator%3A%22Handy%20%2...
Here is a link to a youtube playlist: https://www.youtube.com/user/navyreviewer/videos?query=mecha...
https://www.youtube.com/watch?v=I9IBQVHFeQs
https://www.youtube.com/watch?v=MCxqUJCZGNU
>Only engage the Eaton ELocker™ differential while the vehicle is stationary or operating at speeds of 3 mph or less with minimal wheel slippage.
This specific locker (Eaton G80) is self-engaging up to a set speed which is intended to prevent this from happening, though it has been known to occur.
>The G80 can be very effective when used within its limitations. However its very design can lead it to failure. It requires a certain amount of speed difference between both rear wheels to operate. Basically more slip than you would ever encounter going around a turn, but it will not lock at speeds above roughly 20-30mph. This it where it earned the name "gov-lock". It has a speed governor that operates off centrifugal force inside to govern locking.
When it locks, it locks hard. Imagine one tire sitting still, and suddenly being launched to a speed of 20-25mph. That takes a great deal of force and puts a lot of strain on internals. They have a tendency to break with no warning.
Page also has photos of one that has failed.
http://www.ar15.com/forums/t_1_134/1250761_g80_differential_...
The variety of differential which does not immediately lock one wheel into another is http://en.wikipedia.org/wiki/Limited-slip_differential .
The type of locker I'm more familiar with takes a different approach: the rear end is locked by default but unlocks when it needs to. e.g., going around a turn causes the outside tire to turn faster than the inside one, and the teeth in the locker are angled so the speed difference causes them to cam out and decouples one axle shaft from the diff, letting it spin independently while the inner axle shaft is under power.
I had that system in my Toyota pickup and even in 2WD, it was absolutely unstoppable offroad.
Thanks a lot for sharing.
http://www.youtube.com/watch?feature=player_detailpage&v=508...
What a great lesson for decoupling systems. I wonder what's the software equivalent in design pattern land. The facade maybe ?
http://507movements.com/mm_226.html
There's another video from 1949 about 'How a Watch Works' — http://www.youtube.com/watch?v=508-rmdY4jQ
Or you can find his channel direct on https://www.youtube.com/user/webdev17/videos
Producer: Handy (Jam) Organization ☞
Sponsor: Chevrolet Division, General Motors Corporation
Probably the source of this re-encode, with significantly less artifacts, on archive.org: https://archive.org/details/Aroundth1937
☞ Named after Jam Handy: https://en.wikipedia.org/wiki/Jam_Handy