I'm proving it right now.

I'm sitting down and not sliding all over the place. In order to move, I have to propel myself by some mechanism, such as appendage movement (i.e., contraction and extension of muscle fibers that terminate at more rigid structures, e.g., bones).

Yeah, I'm not seeing how I'd be able to move otherwise, except perhaps by some kind of motion device external to my person.

I don't like to speak in absolutes, though, so I'll still just say I *think* there might be something a little fishy about this video. Maybe.

My first thought was it's one of the self driving suitcases malfunctioning.
My second thought was it's a self driving suitcase that's been reprogrammed to deliver it's payload to a certain plane.
If either is correct, I expect self propelled luggage to be banned immediately, so I really hope it's just strong wind and good wheels.

Yes, that's a larger diameter than an anti tank rifle, which usually was between 12.7mm and 20mm. But compared to, say, a 20mm Lahti L39, this most likely uses a lot less propellant in the cartridge. A lot. Thus less muzzle energy, less recoil, less injuries.

For comparison, Rock Island had a four gauge and a .950 JDJ (that's ~24mm) in one of their auctions, and they took them out for some shooting. Here's the clip: link. And yes, that's Ian from FW in the background.

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.

A few years ago I had lunch at a restaurant with my extended family for some event (can't recall specifically), and as we were standing around talking in the parking lot afterwards, the AN-225 flew over us. We were pretty close to the airport and it was either landing or taking off, so it was quite low to the ground and surprised the hell out of us. We didn't have the slightest idea what it was, but the configurations of the landing gears and six jets made it clear it was damned unusual. Found out later that the beast was one-of-a-kind and a bunch of people were at the airport watching for it, which made it clear how lucky we were to randomly catch that.

I had no idea there was a propeller-based counterpart. I don't know enough about aerodynamics to understand how stacking the propellers like that makes any sense, so I'm just going to assume it's some sort of Soviet technomagic.

Most airliners have wings designed to be used in low transsonic. They can't effectively go faster. They would literally lose lift if they went faster. Their wing shape is made to only delay the onset of shockwaves on top of the wing (flat-ish top), allowing it to safely creep closer to mach1 than otherwise, but not to operate within/past mach1.

Fan/propeller blades themselves are also mach limited.
(They can be designed to be supersonic, but then you end up with something like this... which in hindsight nobody wants : https://en.wikipedia.org/wiki/Republic_XF-84H)
A subsonic airfoil in a fan/propeller, operating near/at supersonic speed, loses the ability to move/redirect air, due to shockwave disruption of the airflow.

Fans/propellers with subsonic blades that spin at subsonic speeds are effectively speed limited. They lose efficiency above ~500 mph, where they begin to stop generating thrust as they travel faster. Their pitch has to increase higher and higher, until they are no longer much of an airscrew and more of a 'feathered' configuration.

Supersonic jet engines use intake devices (such as shock cones) to decelerate incoming air to subsonic speeds, so the compressor (itself a fan, i.e. a highly multi bladed propeller) can operate on that air to compress it and feed the engine combustion chambers.
Airliners have no intake devices to decelerate incoming air, and they would lose engine compression when entering near mach1 speeds.

Furthermore, their bypass fans (which are glorified propellers) would stop providing thrust.

You would need to design different planes (like the concorde). You can't just throttle up a modern airliner and go faster [than X limit] - like you can in a modern car.

-scheherazade

There is so much wrong with this video I don't even know where to start. First, there are only two types of aircraft engines, piston and turbine. When a turbine is used to drive a propeller, it's called a turbo prop. When he is talking about turbo props, he shows pictures of a piston driven propeller aircraft (Cessna 41x), and piston engines are the most common type of engine used on propeller driven aircraft, not turbo props.

He mostly gets it right about turbo jets, except again, every aircraft he shows when talking about turbo jets uses a turbo fan (the F-15 and F-16 both use afterburning turbofan engines). They get their thrust from the hot expansion of exhaust gasses, but he gets it wrong with turbo fans, which get most of their thrust from the bypass air from the fan.

The purpose of the device (a gun) is to propel a projectile at great velocity. The purpose of the projectile is to sometimes kill or injure but mainly just put holes in paper. Just sayin'.

These days firearms are mainly used for shooting steel, cardboard and paper targets. I own competition guns made solely for shooting cardboard and steel. The market determines what they are built and bought for, not you.

Now, you've changed the topic to "responsibility". I hadn't seen anyone here argue he lacked responsibility for the operation of the device. On top of that, if the device is faulty and it malfunctions you are not necessarily liable for what happens. There is case law on this in the USA.

There are accidental shootings. I've literally got a degree in treating people who have been victims of accidental or purposeful shootings. There is lots of case law covering accidental shootings (and the law says that there are accidental shootings). Accidental doesn't mean there won't be repercussions.

Energy is neither created nor destroyed. A V8 converts gasoline into CO2, water and heat which increases pressure within a cylinder and in turn propels a piston that moves the car. This uses air to move a piston (and could be used to move a car). Gas = air in this example.

My car was affected, but has already been fixed.

Jalopnik had an article about this a few days ago - http://jalopnik.com/the-complete-story-of-takata-airbags-and-the-biggest-re-1780143347

Takata used to use a safer but more expensive propellant (car to guess why they changed?), and have now changed the formula to include a drying agent to help prevent the problem in new airbags. Their issues were also exacerbated by problems they had moving their production facility to Mexico on the cheap.

There seems to be a clear trend there: cost savings trump product safety.

Wow, angry and stupid. Grade-school education and white skin not enough to propel you into the top 1%? Boo hoo.

How's that working out for you?

Interesting. Does that account for the limits of the human body in terms of (long-term) exposure to G-forces from all that acceleration?

I'm sure we could use nukes to propel a craft to very high speeds very quickly, but I'd wager that limiting the acceleration to human tolerance would require that to be spread out over a much longer span of time.

A quick google search suggests that nobody really knows exactly how much we could handle in terms of long-term exposure to acceleration G-forces:
https://space.stackexchange.com/questions/6154/maximum-survivable-long-term-g-forces
(apparently the highest load we've ever tested on humans is 1.5G for 7 days -- without doing any math I'd wager we'd need a lot faster acceleration than that for a lot longer span of time to get to even 1/10th of c)

Looks to me like the only benefit they're claiming is that the mechanism is mechanically simpler. That's probably a reasonable benefit, but they've had 100 years to perfect more traditional guns so I imagine there would need to be a pretty substantial advantage to be worthwhile, particularly since it needs special ammunition and all the faffing about with supply chains and inventory that it would necessitate.

It's possible the open chamber would help heat-wise by preventing the bullets from "cooking off" which is a problem with some machine guns that happens when the chamber gets hot enough to ignite the propellant making the gun run away, firing without the trigger being pulled. That wouldn't apply to an electrically (or whatever) driven gun like this, though.

So... yeah, it's probably just one of those "let's try it and see what comes of it" sort of things, because I don't know why you'd want a gun with funky ammunition that takes up more space because it might be slightly more reliable than the otherwise very reliable existing guns.

From an article on ArsTechnica:

SpaceX's founder, Elon Musk, has said it costs the company about $60 million to build a Falcon 9 rocket. The propellant itself only costs $200,000. Thus there is the potential to slash the costs of spaceflight by 10, or even 100 times.

@Asmo
i get what you are saying but i think you are missing the insidious implications that this new system of indoctrination represents.

i think @ChaosEngine's term 'stealth totalitarianism" is rather clever..and apt.

i agree with you on the points of peer pressure and how people can easily be manipulated.we are all,to varying degrees,subjected to a plethora of propaganda and targeted rhetoric,all meant to mold and shape our opinions in order to sustain the status quo while giving the impression that somehow our conclusions are an organic and natural response,when in reality we have been duped.

on that point we agree that this is not actually something new or novel but an old,tried and true method of social control.

what is new about this 'gaming" system,is that it is not taking the more subtle and passive approach of what current and supposedly "free" societies now implement to control public opinions and attitudes in order to either remain in power,sway the public into policies against their own interest,or create an atmosphere of fear to foment opposition.

this new system is actually aggressive.
this system will actively use its own population to do the oppressing,manipulating and controlling FOR them.

it is brilliant in it's simplicity.
it will use very human attributes we all possess in order to enact a better system of control,all the while having the appearance of being a harmless and innocuous social media competition.

but it is anything but harmless.
nor innocuous.
it will and can affect every facet of someones life.from their job to where they will be able to live,to even HOW they live.

think back to the times of east germany and the stasi,or the weimar republic,or even the soviet union of the 80's.

all used elements this new gaming system is representing,but those systems of control,while relying on the public to do much of its surveilling,all had one thing in common that they ALL relied heavily on:fear.

fear of reprisal.
fear of exposure.
fear and suspicion were the driving forces that kept those systems in power and the people in a perpetual state of paranoia.

the dread of the midnight knock.
of jackboots and black bags.

but those systems of control were fragile and once even a little resistance was exerted those systems crumbled incredibly fast.

this new system is far more subtle and devious in my opinion,because it removes the spectre of an imposing and oppressive government that will respond with violence and replaces it with the citizen to do the work for them.

the government does not have to do anything.
your neighbor will,and not because of some fear-based reason but rather for points to propel their own ambitions.their own selfish desires.

the wholesale implications are absolutely terrifying if you really think about it.

i would speculate that within a very short amount of time dissent and criticism of the chinese government will all but have vanished.replaced by a obedient and compliant population.

not because they are afraid of reprisal from the government but rather fueled by their own selfish desires for a better job,better living quarters,more privileges etc etc.

so a seemingly benign system utilizing social media will become of a self-propelled system,where those who do not tow the party line soon face joblessness,homelessness and ostracization.

not because the government strong armed them into submission,but rather their own neighbors.

so you are right.
there is nothing new here,but this system has taken the old forms of social control and brilliantly utilized one of humanities greatest weaknesses:selfishness.

it is the simplicity that makes this so brilliant and yet so horrifying at the same time.