Helicopters Won’t Just Drop Like A Rock If The Engine Dies
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Helicopters Won’t Just Drop Like A Rock If The Engine Dies

September 20, 2019

Helicopters will drop like a rock when the
engine shuts down. In fact, you have a better chance at surviving
in a helicopter when the engine fails than you do in an airplane. Helicopters are designed
specifically to allow pilots to have a reasonable chance of landing them safely in the case
where the engine stops working during flight, often with no damage at all. They accomplish
this via autorotation of the main rotor blades. Further, when seeking a helicopter pilot’s
license, one has to practice landing using this no-power technique. When practicing,
instead of actually shutting the engine off completely though, they usually just turn
the engine down enough to disengage it from the rotor. This way, if the student encounters
a problem during a no-power landing, the helicopter can be throttled back up to avoid an accident.
Given that this isn’t an option during actual engine failure, it’s critical for helicopter
pilots to practice this until they have it down pat. A landing via autorotation is also sometimes
necessary if the rear rotor blades stop functioning properly, no longer countering for the torque
of the main rotor blades, so the helicopter will spin if the engine isn’t turned off.
Whether this happens and the pilot shuts off the engine or in the case of actual engine
failure, once the engine drops below a certain number of revolutions per minute, relative
to the rotor RPM rate, a special clutch mechanism, called a freewheeling unit, disengages the
engine from the main rotor automatically. This allows the main rotor to spin without
resistance from the engine. Once the engine fails or otherwise is shut
off, the pilot must immediately lower the pitch, reducing lift and drag, and the helicopter
will begin to descend. If they don’t do this quick enough, allowing the RPM of the
main rotor to drop too far, they’ll then lose control of the helicopter and will likely
not get it back. When this happens, it may well drop like a rock. However, this isn’t
typical because as soon as the freewheeling unit disengages the engine, the pilot is trained
to respond appropriately immediately. Exactly what the correct glide angle is to
maintain optimal rotor RPM varies with different helicopter designs, but this information is
readily available in the helicopter’s manual. The glide angle also varies based on weather
conditions (wind, temperature, etc.), weight, altitude, and airspeed, but in all cases a
correct glide angle has the effect of producing an upward flow of air that will spin the main
rotor at some optimal RPM, storing kinetic energy in the blades. As the helicopter approaches the ground, the
pilot must then get rid of most of their forward motion and slow the decent using the stored
up kinetic energy in the rotors. If done perfectly, the landing will be quite gentle. They accomplish
this by executing a flare, pitching the nose up, at the right moment. This will also have
the effect of transferring some of that energy from the forward momentum into the main rotor,
making it spin faster, which will further allow for a smooth landing. Because the flare
will often need to be somewhat dramatic, the tricky part here is making sure that the rear
of the helicopter doesn’t hit the ground. Ideally the pilot executes the flare (hopefully
stopping most all the forward motion and slowing the decent to almost nothing), then levels
the nose out just before touchdown. Autorotation may sound like a fairly complex
and difficult thing to do, but according to one instructor I briefly chatted with about
this, it’s really not all that difficult compared to a lot of other aspects of flying
a helicopter. In fact, he stated that most students have a lot more trouble when they
first try things like hovering, than they do when they first try a no-power landing.
Granted, this is partially because students don’t try autorotation landings until they
are near the end of their training, so they are more skilled than when they first try
a lot of other maneuvers, but still. It’s apparently not nearly as difficult as it sounds
and most of the problems students have just stem from being nervous at descending at a
higher rate than normal.

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  1. I'll have you know I'am a expert Arma 3 player and I know how helicopters work. If the engine cuts out, your screwed.

  2. A friend of mine got shot down over Vietnam. The chopper dropped like a rock into the south China sea. It sunk in less than a minute. The crew tried swimming to shore but got picked up by air sea rescue. Air sea rescue commented they were lucky to not be eaten in the shark infested waters, and to be thankful they didn't make it to shore, which was overrun by Viet Cong soldiers.

  3. The premise that helicopters are safer than airplanes during an engine failure is false.
    While it's true that helicopters can autorotate, they can only do so in a very fine window while flying above a certain altitude and going over a certain speed.

    Get an engine failure while hovering, flying slow or flying low and you will not be able to autorotate. Also the reaction time for initiating autorotation is very low in the best of cases. It's one thing doing autorotations while practicing engine failures (and expecting it) and completely another reacting to the unexpected event in less than ideal conditions. Statistics on crashes and successful autorotations tell a different tale than your video.

  4. I like planes more because you can just glide if the engines fail. Cars are my favourite because you can stop them without them dropping from the sky

  5. Did you just watch the Smarter Every Day video then make this…. You released it a week or so after he released his video?

  6. I still think it's easier to land a plane with an engine out. I mean the plane is fixed wing so it turns into an unpowered glider. As long as your hydraulics are powered by a backup APU or battery, you should be good. Just think to yourself that I can no longer fly straight, I have to look for a place to land from here on out.

  7. This is why I'd rather fly a helicopter than A fighter jet but you can't eject in a helicopter but that still makes safer but in a fighter jet the ejection seats can fail this is also one reason a helicopter is Safer.THIS IS ADVICE

  8. maybe not always, but it certainly happens, especially in a fuel control or governor issue or bad fuel or fuel contamination issues. anything mechanical on engine can be bad.

  9. Smarter Every Day made a video about auto rotation. It's called "strapped to a falling helicopter' or something like that.

  10. I watched the video from the link and the guy doesn't land the copter unpowered. He throttles up right after the flair which keeps him well above the ground. I assume this is because to actually land without powered rotors would cause damage and be anything but gentle.

  11. This is fake cus a helicopter can't float on water most planes can s helicopter can't glide from great hights a plane can

  12. Hovering steady is pretty damn hard to do when your first learning. It's extremely easy to over correct on a little mistake and you end up swinging around all over the place. Actually flying a helicopter once in the air and moving is pretty easy.

  13. Someone should forward this video to Neil DeGrass Tyson.
    SERIOUSLY, the "PhD Physicist" doesn't understand this concept of helicopter flight. Apparently, not all PhD programs are the same… Cough*Affirmative Action*Cough

  14. My old airplane instructor was a reserve helicopter pilot and told us the time he had to do autorotation landing in the Army after an engine problem.

  15. At one time I worked at a place where a neighboring organization had a number of helicopters. They had their pilots practice autorotation landings often. However, they would appear to "glide" in for that landing. Naturally this would be hard on the skids, so they had liners on the skids which they changed often.

    I am intrigued that another contributor wrote in here, likening the autogyro to a autorotation landing. Though I have been told that the blades on an autogyro were not adjustable. Anyway, my old Dad talked about these a lot, so I had an idea what the pilots were talking about when I was introduced to autorotation.

    Fascinating! As all of aviation is.

  16. Most of my helicopter experience is from a video game in the past called Flight Simulator 2000 (I am not sure if "2000" is the right name.) as a kid. It is a game that I have heard used in actual flight training for pilots. It is because they put almost everything you would experience in flying (like sudden appearance of rogue winds causing your aircraft to start spinning around in turbalance and you struggling to gain back control). In the game I realized helicopters are very tricky in a different sort of way than planes. You have a lot of control of the craft and is safer in certain aspects. The problem is you're much more influenced by the atmospheric air conditions you fly in (one of them includes the various kinds of winds blowing around), to a point it provides limitations for you to operate in and also dangers to be careful for. The dangers… OMG! It can be nasty and scary if you are not aware of them. I noticed as a young kid I kept experiencing sudden hit by an ambiguous force that caused my chopper to suddenly start spinning around where I had to struggle to maintain control. Sometimes the engine would stall too. On certain occasions it was so strong I would lose all control and flail around until I crashed. I thought it was a glitch in the game until one day my parents and the rest of my family saw it happen. It sparked a discussion about helicopters. This is when I learned that helicopters are known to do that sometimes depending on what altitude you fly in, and the type of winds blowing around. Then it was brought to my attention some of my family actually knew some people that experienced this stuff, and either lived or died in the crash. From this I learned helicopters is something that has a trade off regarding its mobility. You can move "anywhere" in "any" direction, but you are more limited than a plane when it comes to altitude, other dangers in their surroundings, and more vulnerable to drastic environmental factors. (Basically a chopper had as much disadvantages and advantages over a plane.) Basically I surmise the REAL reason why helicopters have a lower amount of crashes than planes is because pilots have to be more aware of these issues and more inclined to avoid anything they suspect will put them into danger.

    (Example: Helicopters do not like to hover around electrical cables. I have heard pilots are told and actively choose to have a vast distance between them and the cables. It is because there have been cases of something occurring where the aircraft somehow managed to be blown uncontrollably into the lines, or the pilot gradually wobbling in the direction off too close then the pilot realized (from simply hovering there and not paying attention properly or misjudging his distance) and accidentally crashes into it. This causes a advisory warning to pilots to never assume you can't be blown into stuff in your environment and you have full control. You might think you are at a safe distance but things can quickly change. It is best to always position yourself in a way where a strong enough wind or your own incompetence won't get hit the cables)

  17. A better explanation would be that it works like maple tree seeds or "helicopter" seeds falling. For people who aren't from Canada and aren't familiar with these, here's a link: https://www.youtube.com/watch?v=uJjyAiogVWU

  18. That thumbnail… Next frame is when the shit literally hits the fan. Rather the main rotor is going to strike the tail structure in only a dozen or so degrees of rotation.

  19. Today I learned this guy is an idiot. The speed in which you auto rotate to the ground is not a cozy landing. Gliding an airplane down is.

  20. Ready to learn more amazing facts? Then check out this video and find out the answer to the question- How Did Lunar Landers Re-Launch When There’s No Oxygen?:

  21. He just reads exactly this article. exactly every word of it. https://gizmodo.com/how-helicopters-are-designed-to-land-safely-when-their-1708128868 at least put some effort in it.

  22. Try autorotating your helicopter after an engine failure while hovering … GOOD LUCK WITH THAT, you WILL "Drop Like A Rock"

  23. Blah blah blah blah blah… Shesh…a lot of words for not a very simple and specific explanation. Like the guy below me said..just explain the process with a 30 second vid.

  24. I saw a clip of some japanese game show of a helicopter pilot killing the engine and landing safely like 15 years ago

  25. i still don’t trust helicopters. they’re easily upset and there are just too many components that can go wrong. at least when a fixed wing engine fails u can glide down into a field or road or mush it into tree tops if u have to

  26. I would yaw the helicopter 180 while pitching it to prevent tail contact with the ground when landing during autorotation.

  27. the video you need to watch is the one in the links, not this video of some guy talking for 4 minutes without a single clip of an autorotation.

  28. Thanks for reading gizmodo script for us word by word.😄😂🤣


  29. You probably want to credit Gizmodo. This explanation is nearly word for word of their article on the subject: https://gizmodo.com/how-helicopters-are-designed-to-land-safely-when-their-1708128868

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