@noims -- My grandfather had about 10 war stories that he rotated through telling, pretty much exclusively after one of my uncles "broke the dam" by asking him to recall things as they were at the Oshkosh air show standing next to a P-47 airplane like he had worked on.

By the time that happened, my grandfather was in his 80's and in very good physical and mental shape (cattle rancher that did daily work manhandling heavy feed bags around, etc.) but had a quirky personality because he was 90%+ deaf. I don't think that was a result of the war, hearing problems seem to run in the family.

Anyway, he frequently used those hearing problems as an excuse for not having to interact with people. He had hearing aids, but he'd turn them off most of the time and just ignore people. I think some of that was being an introvert, and some was probably lingering "shell shock" / PTSD effects. But overall he really adjusted back to civilian life just fine. Got a degree in education on the GI Bill and taught and coached basketball to High School students, then worked as a small-town Postmaster, and eventually retired to work the ranch. I don't think any of us in his family, including his wife and children, thought of him as being "impaired" by the mental effects of the war. But it was clear that some of what he experienced had a very deep, lifelong effect on his outlook.


I wrote out the 3 stories of his above because they seemed to be the ones that had the most emotional impact on him. To me, it was interesting that a lot of stuff outside of combat hit him the hardest. He also had more traditional "war stories" stuff about victories and bravery, like when his unit captured / accepted the surrender of a young German pilot in a Bf-109 who deserted to avoid near certain death from flying too many missions after the handwriting was on the wall that the allies were going to win. But by far, he got more choked up about the other stuff like having to knock that French girl off her bike and seeing starving civilians and being unable to help them much.

Like you said, more banal stuff side-by-side with or against a backdrop of horror. I think it's pretty much impossible to imagine what those sorts of experiences in war are really like and what being in those situations would do to us mentally. And then WW2 in particular just had a massive impact on the entire generation. Basically everybody back home knew multiple people that went away and never came back. Then when some did come back, they were clearly different and yet reluctant to talk about what happened. Pretty messed up time to live through, I guess.

So, I guess they need to keep that rotating mass fairly well balanced.

I like the rotating triple A one.

shit I wish I knew. hoping for a fix myself. Told my friend I was in a place not to be disturbed. Now he has Dick in the Box playing on rotation lol

I can give you a description of the bit and my opinion.

A Tom Thumb bit is jointed in the middle and has shanks for leverage. So it has a dual action. When light pressure is used it works on the gums and corners of the mouth. When the reigns are pulled harder the jaw is squeezed while the shanks multiply the force and the center joint folds upward to apply pressure to the roof of the mouth. It's kind of like the volume going from 1 to 11.

Uses:
In theory it should act like a traditional Western bit with the added advantage of rotating the shanks independently...so you can make pressure changes on each side of the mouth independently. In actual practice, it pinches the horses lip in this situation and horses tend to react by tossing their head up or holding their head in an unnaturally high position. With a strong pull it becomes extremely severe. Using it requires a very light hand.

I have used a Tom Thumb successfully with a well trained horse that required no head control but had developed a bad habit of testing his rider by picking up his gate and then bolting. The bit allowed me to ride with no hand but when the horse stretched his neck to take control he ran into the bit. When he relaxed back to the correct position, the pressure was gone. Eventually he didn't want to cause his own discomfort and once he'd broken his bad habits the bit wasn't necessary.

In my opinion, the Tom Thumb appears to check a lot of boxes but in reality it does few of them well. It can work for the right horse, with the right rider, in the right circumstances.

Roy is clearly an inexperienced rider and his personality demands that he assert control, even when he's out of his depth. He's riding a gaited horse (I think it's a Tennessee Walker but my daughter disagrees) and he seems to be trying to make it move like a Quarter Horse. My guess is he's trying to ride in like a cowboy but the horse naturally moves like pretty princess horse. Chaos ensues.

I hope that makes sense. I tried to avoid horse-people terms. If something's unclear or if anyone feels I'm wrong, then I welcome comments.

Counter-rotating propellers sparked my curiosity when I first saw them on a British Seafire Mk46 at a flight show in the early nineties.

So my amateur's answer would be that it's about the problem of turning the engine's power into thrust. With increasing power, you can either increase the propeller's RPM or its area. So you either a) spin it faster, b) increase its diameter, c) use a more favourable blade geometry, d) add more blades.

a) and b) both lead to blade tips moving faster, and once they approach the speed of sound, wave drag sets in and ruins your day. b) also runs into issues in terms of ground clearance. Thus the Kim Jong-un blades on planes like the An-70: short and fat.

c) is rather difficult to do in terms of manufacture -- that's why more pronounced blade shapes are a relatively recent development.

d) on a single propeller decreases the efficiency of each blade as it passes through the previous blade's vortex. That's why, for instance, German planes in WW2 almost exclusively relied on 3-bladed propellers with increasing blade size, whereas Supermarine went to four and even 5 blades rather quickly. You can work the issue to a certain degree by modifying the blade geometry, thus the 8 blade props on a modern A400M.

Adding more blades by adding another propeller gets around d), although the aft prop still loses efficiency compared to the front prop. On the other hand, counter-rotating props massively reduces problems with torque, which can be rather horrendous for single engine prop planes. The Bf 109, for instance, is (in)famous for being difficult during take-off as it pulls to the side quite violently.

But you didn't encourage them to ROTATE THE GOD DAMNED CAMERA, did you?

Comment hidden because you are ignoring dag. (show it anyway)

Sweet hair feathering. Have been listening to the Guardians of the Galaxy soundtrack a bit on Spotify so have been getting this song in rotation a bit.

What happened? Bad luck with a tail rotor failure? Gust that caught and swung it? Looked like the pilot lost tail rotor authority slowly and it started to rotate and he did the smart thing; grounded it.

or I'm completely wrong.

I'd wager that a reasonable percentage of the lucky guys that survived a full tour of duty wouldn't agree with the assessment of flak jackets being essentially "unstylish 40 pound vests".

Also, the video makes it sound like the success rate of coming back from a single mission was 25-33%. I think those numbers are more accurate for the rate of completing a full tour of 25 missions (before being rotated out). The number I recall is about a 4% loss rate on a single mission:
100%-4% = 96%
.96^25 = 36%

If the chances of coming back from a single mission were 33%:
.33^25 = (pretty much zero).

I wouldn't want to chance my life on a roll of the dice where I die unless I roll a 5 or a 6, but that's pretty close to accurate...


Those nitpicks aside, still a great video that gets the newer generations that are too young to either have a grandfather from the war or to have watched Memphis Belle a bit of a sense of what those guys went through.

I remember being stoned with some friends in Golden Gate Park at night in the early aughts. Someone was flying one of these with rotating glowing lights but we couldn't hear a sound coming from it from how far away we were - it really seemed like a UFO.

Diagram of re-entry for the Soyuz:
---------------------------------------------
http://spaceflight101.com/soyuz-tma-20m/wp-content/uploads/sites/77/2016/09/6618866_orig.jpg

Orbital Module:
---------------------
It houses all the equipment that will not be needed for reentry, such as experiments, cameras or cargo. The module also contains a toilet, docking avionics and communications gear. Internal volume is 6 m³, living space 5 m³. On the latest Soyuz versions (since Soyuz TM), a small window was introduced, providing the crew with a forward view.

Service Module:
---------------------
It has a pressurized container shaped like a bulging can that contains systems for temperature control, electric power supply, long-range radio communications, radio telemetry, and instruments for orientation and control. A non-pressurized part of the service module (Propulsion compartment, AO) contains the main engine and a liquid-fuelled propulsion system for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the Intermediate compartment. Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the ship.


Consequences of bad jettisons:
------------------------------------------
The services modules are jettisoned before the spacecraft hits the atmosphere. A failure or partial jettison of the modules means that the capsule will not enter the atmosphere heat shield first which can lead to a number of scenarios:
- Capsule pushed off course (by hundreds of km)
- High sustained g-loads on reentry
- Plasma on reentry can burn through the craft if the heat shield is not exposed and oriented properly resulting in loss of crew.

https://en.wikipedia.org/wiki/Soyuz_5
https://en.wikipedia.org/wiki/Soyuz_TMA-10
https://en.wikipedia.org/wiki/Soyuz_TMA-10

3) it moves backwards because the force is applied to the entire system/bicycle. The wheel going backwards turns the gears and chain, rotating the pedal 'forwards' (rotating it in reverse). Because the wheel is much larger it travels much farther back than the pedal rotates forwards, even with 1:1 gearing the pedal actually travels backwards slightly compared to the ground, but in higher gears it gets much easier.
It's because the tire is so much larger than the crank, that makes it easier to rotate the tire than the crank even at 1:1, so it goes backwards.
It's counter intuitive, but I actually checked my work and yep, my bike went backwards in all gears....no sliding needed. Try it.

I guess the hint for these is the rotational test that they show at the first.

1) A sticky object that would let go like a wall crawler that climbs down a wall would create this effect. (see below)
2) You can't. As you approach infinite speed it would get very close. (see below)
3) The bike will move forward. (see below)
4) The outside parts of the wheels that overlap the rail. Also if the train has a flywheel that is larger than the wheel size the bottom of the flywheel would also always move backwards faster than the train was moving.

1) He says "what object is inside?" so I'm not sure a liquid would count. Also a viscous liquid would flow a slow rate and would probably not stop and start. You might be able to get a viscous liquid to stop and start if you had fins, but that still might just move slowly or gain enough momentum to roll fast without any flow.

2) A little excel calculation shows that the average velocity approaches twice the initial but will never hit it.

attempted m/s - total time - average m/s
1 100 1
2 50 1.333333333
3 33.33333333 1.5
...
200 0.5 1.990049751
201 0.497512438 1.99009901

3) I'm not sure if the parameters of this experiment are explained sufficiently.

If it is allowed to slip then no matter the mechanical advantage a hard pull should always be able to get the bike to skid back and defeat friction.

If the bike is not allowed to slip on the ground then I don't understand how it could ever move backwards, the only options would be that it doesn't move at all or it moves forward.

If it can't slip then the ratio of the pedal to the wheel is what is in question. Bikes only have gear ratios higher than 1 and the crank is smaller than the tire so the tire will always rotate more than the crank thus the bike should move forward.