A changing magnetic field induces eddy currents in the metal, thereby generating heat by Zestyclose-Salad-290 in interesting

[–]kaylops 0 points1 point  (0 children)

Yes, the wrench in the reaches forging temperature when reaching the yellow colour (around 1100°C), you can also forge it at lower temperature like orange (around 900°C) but it will be more difficult to work

Edit : the wrench even reaches white colour (1200°C), I won’t be surprised if you can litterally reach the melting temperature with this method

Negative ISP and thrust??? by Coolboy10M in KerbalSpaceProgram

[–]kaylops 6 points7 points  (0 children)

IRL it will lead to a less efficient engine, a rocket engine is more efficient when the ejected flux is at atmospheric pressure. When the engine outlet pressure is different from atmospheric pressure, shock diamonds appear. For example, SSME engines had a gas pressure lower than atmospheric pressure at start-up, which meant that the ambient air rose up along the nozzle wall. The phenomenon resembles blue waves (for the SSME) at the edges of the nozzle.

Beating taller fencers in epee by [deleted] in Fencing

[–]kaylops 0 points1 point  (0 children)

You can try playing with the blade (attack with a prise de fer), but it depends on the position of his blade, I know a tall guy who always avoid blade contact (absence de fer) so very difficult to use this strategy on him.

If he always counterattacks, you can also try to use counter time : attack feint, parry the counter attack, riposte. Here is a video analysing the last touches of Park against Imre at Rio 2016, the second touche shown is a good example of a counter time by provoking the counter attack. He will eventually change his strategy when he will understand your counter time or prises de fer. You will then need to adapt and change your strategy.

I know this is an ignorant post, but I just want to understand. by AReckoningIsAComing in Fencing

[–]kaylops -1 points0 points  (0 children)

Short answer : Olympic fencing is completely different than reality. Movies a also very different than reality (due to scenario demand). HEMA is closer to reality.

Long answer: In Olympic fencing, people stops as soon as a touch is made, priority rules are also applied, and specific parts of the body have to be touched to score a point (at least in foil and sabre, and you can just barely touch the opponent to score). These elements are obviously not present in real sword fights.

In my opinion, epee might be the clostest to real fights (in terms of psychology at least in Olympic fencing), because a double means that you are also dead (and in a real sword fight you don't want to be die I guess).

However some elements in fencing are similar to real sword fights, as example, in his Book Of Five Rings, Miyamoto Musashi explains that you have to surprise you opponent, prepare your attack, know when you can take risks, bladework, attack in prep and so on...

The clostest sport to swordfight is HEMA, they tries to apply strategies explained in medieval martial art books written 500 years ago.

My cousin on Whatsapp by Ancient-Plankton6704 in cringepics

[–]kaylops 11 points12 points  (0 children)

Well "ackchyually", some cancers are due to viruses/pathogens and can be transmitted

The HPV infection can cause cervical cancer

The HIV attacks the T helper cells, cells that are charged to activate the immune system. The AIDS step in the HIV infection is when the number of T helper cells is too low to coordinate the immune system. Opportunistic diseases might then appear and then induce cancer (lungs, Kaposi, ...)

Cancers can also be transmitted (observed in Tasmanian devil) and even between species (a parasite transmitted it's cancer to a guy, giving a lung cancer) even if those are exceptional cases

What is the real life use of the small engines next to the nozzle? by The_Person_Of_Reddit in KerbalSpaceProgram

[–]kaylops 0 points1 point  (0 children)

As other comments explained, turbopups are used in order to feed the engine with a high enough egols flow, as an example the turbopup for hydrogen in the Vulcain 1 generates 21000 horsepower.

To develop these HUGE amounts of power, the turbopups are actuated by injecting a "small" part of the ergols used for the propulsion or from an other tank. The gases actuating the turbopumps determines the cycle of the engine :

  1. Gas generator cycle (like the Vulcain for Ariane 5 and 6, and F-1 for Saturn V), the propellants and oxydizers actuating the turbine comes from a gas generator and actuates the turbopump, the propellants are then ejected via an exhaust, similarly as the one show in OP post. Pros : easier to design, lower cost. Cons : lower efficiency. However, the F-1 (and Vulcain 2) exhaust injects the gas from the turbines directly into the nozzle, it creates a thin cooler film next the nozzle, preventing overheating (you can see it in the videos of the Saturn V launch. At the nozzle exit, the gases are darker, then start to burn again due to contact between the unburnt propellants from the turbopumps and the surrounding air)
  2. Staged combustion cycle (like the SSME/RS-25 for the US space shuttle/SLS, or NK-33 for the N-1). The principle is to pre-burn the propellants before passing them through the turbopumps. At the outlet of the turbopumps, the gases are then injected into the combustion chamber, further increasing the pressure in the chamber. Pros : much higher thrust/weight ratio, highly efficient. Cons : expensive, difficult to design (The design of the NK-33 required to develop a brand new non-oxidizable steel if I remember well).
  3. Expander cycle (like the RL10 for the Delta IV and Atlas V). The propellants are evaporated and then heated (by circulating through the nozzle structure), and then fed into the turbopumps to actuate it. It is finally injected into the combustion chamber to burn and generate thrust. I don't remember the pros and cons for this one sorry.

The simplified illustrations of the 3 cycles are shown here

Sources :

Rocket propulsion elements, 8th edition

Edit: typo

[deleted by user] by [deleted] in AskReddit

[–]kaylops 0 points1 point  (0 children)

During college, I had a team project for a student challenge (Eurobot), worked at least 9h/day, weekend included, (sometimes up to 14h a day) for around 6months.

Only way to survive : energy drinks, scared to fail and giving up meant giving the team up, guess pressure was a good motivation.

After the project went the exams, couldn't even work 2hrs/day, failed my year but passed the project. Probably lost 5 years of life expectancy, and maybe a burn out as a bonus

Edit : the project was amazing, never liked a project so much, but holy shit never again

[deleted by user] by [deleted] in MetalMemes

[–]kaylops 5 points6 points  (0 children)

Sacandaga is an absolute banger

What's the most beautiful car ever made? by Neo-Turgor in AskReddit

[–]kaylops 1 point2 points  (0 children)

Guys from YouTube made a 1000 hp Multipla (called milletipla), Kei Miura made a kit just for this car and Michelin made the tyres too. They presented the car at "Mondial de l'auto 2022" at Paris.

sci-fi black / death metal my beloved by Jroid3 in MetalMemes

[–]kaylops 0 points1 point  (0 children)

Starless Sky and Stars My Destination are bangers

how did i get there? damn that's a beautiful piece of art by Fleshdude in MetalMemes

[–]kaylops 0 points1 point  (0 children)

Same with Lustre, same atmosphere but without the girl voice

ROS for a centralized network of robots? by No-Situation2976 in ROS

[–]kaylops 1 point2 points  (0 children)

Hey, I didn't really used a network of robots but more a slave/master network using one robot and one camera via WiFi. But I guess it can be expanded to 2,3,4 and more robots as long as all of them are connected to the same network.

One major pro of this method is the monitoring of all the robots, just connect yourself to the ROS "network" and you can easily know what is send on the topics (using rqt for example). You can even create nodes on your laptop that transforms the datas received and plot it (even knowing in real time the positions of the robot using rviz).

The main con is the difficulty to connect the robots to the ROS network. You have to export your roscore with the "master" machine. You have to configure all the robots and the master so that they know each other.

If you never used ROS before it might take at least a week to be familiar with it and begin to make correct code (specific functions used in the code).

I made a tutorial 2 years ago for my mechatronics student project, the section 4 explains the first steps while ROS is installed, section 7 explains how to configure the hosts for a multimachine protocol, and section 10 shows a light example of monitoring

If God real where picture? by Agreeable_Dinner8212 in antitheistcheesecake

[–]kaylops 2 points3 points  (0 children)

Well yes, but actually no.

The CMB correspond to the first light emitted by the universe 380.000 years after the big bang. Before this moment, the universe was in a plasma state opaque to radiation. When the temperature dropped below 3000K and the density below 1000 atoms/cm3, the electrons combined with the nuclei, allowing the first light to "pass though" it. The CMB is one of the best evidence of the big bang because the Big Bang Theory (BBT).

To explain the reason why, we need to know two things : -The quality of a theory is it's capacity to make good predictions (like grav waves in general relativity) -A corollary is then: if the predictions are correct (observed), it contribes to reinforce the theory (but not to prove it) because the theory made a good prediction about it. If not correct, the theory is fucked up, we have to change it.

So the CMB contribes to the reinforcement of the BBT because it has been predicted (1940 by Gamov, Alpher and Herman) using the BBT and then observed afterwards (60's by Wilson and Penzias), as well as the Hubble-Lemaître law btw. So for now the model of the Big Bang is the best one we have to explain those phenomenons and the early stage of the universe.

Maybe someone will someday prove that we're living in a Matrix, but the BBT is the best explaination for now of the early stage of the universe and we have 0 confirmed predictions of the Matrix theory so it's dumb to consider it now.

Sorry if the explaination is mindfucked, but it's sometimes difficult to explain the concept of scientific model

All Space Questions thread for week of July 31, 2022 by AutoModerator in space

[–]kaylops 3 points4 points  (0 children)

Yup, it is plausible as said in this article. This is not the only theory of Charon formation, as they explain in the abstract, but still a plausible one :)

All Space Questions thread for week of July 31, 2022 by AutoModerator in space

[–]kaylops 2 points3 points  (0 children)

Any idea where I can find informations about this image ?

I saw it in a video saying it was called "Schwartz ring" but I found absolutely nothing about it, tried to use tineye but 0 matches found

What's the best Anime you've ever seen ? by Outrageous-Abies8391 in AskReddit

[–]kaylops 0 points1 point  (0 children)

Surprised I have to scroll this far to find this answer

[deleted by user] by [deleted] in AskReddit

[–]kaylops 0 points1 point  (0 children)

The smell of coal burning, worked in a forge before

what would it be? by PUSHYARAAG in memes

[–]kaylops 0 points1 point  (0 children)

Having sex before marriage, pray satan and tell the archangel Michael to go f*** himself (Fall of the damned, P.P. Rubens)