Helicopter Physics Series – #3 Upside Down Flying With High Speed Video – Smarter Every Day 47

Helicopter Physics Series – #3 Upside Down Flying With High Speed Video – Smarter Every Day 47


Hey it’s me Destin. Welcome back to Smarter Every Day.
So last week I described collective pitch control for a helicopter,
I described cyclic pitch control for a helicoper, and I also
described anti-torque pitch contol But this week we’re going to combine them all and describe something called collective-cyclic pitch mixing. It’s pretty cool, and it’s basically how every helicopter pilot flies, including Carl in this case.
The way I’m gonna describe this to you is by setting up and showing you a high speed video clip of Carl
flipping the helicopter over and flying inverted. [rotor noise] You’re about centre of the frame, maybe a little less right there. [rotor noise] [rotor noise] That’s gonna be good. It’s pretty interesting, because if you think about it he’s having to use both collective and cyclic to make the sweep, go up, and then he’s going back to negative collective. [music] And then he’s balancing it up there with cyclic all the time. So you can see he’s never using one particular input. It’s always a variation of both. OK so if you didn’t really understand what was going on there, I asked Carl to do something else for us. I asked him to mount a camera on the back of his helicopter looking at the swashplate, and then take a normal flight so you could see the collective-cyclic mixing, but here’s a couple of things to keep in mind. At the top of the screen you’re going to see the rotors, and at some point it’s gonna look like the rotors are bending. That’s actually not happening. What you’re seeing there is something called the rolling shutter effect. The second thing you’re gonna see it looks like the rotor shaft is speeding up and slowing down wildly. That has to do with the frame rate of the camera. That’s called aliasing. If you want to know what aliasing is, just click this box over here and I’ll explain that to you in greater detail. [electronic servo sounds] [music] [music] OK I’ve been getting a lot of comments on these
videos about whether or not an actual helicopter can do these types of manouvres.
And the answer is yes, and no. Helicopters can do this if they’re designed for it,
however you’re limited by the meat servo sitting in the seat. A human can only
take so much accelleration. So how do you scale up what you’re seeing on this RC helicopter to a real helicopter? Before they flew a space shuttle into space they had to do a wind tunnel test on it somehow right? Well it gets complicated but there’s a term called similitude and similitude has to do with the geometric kinematic and the dynamic similarity between a small scale object and a full scale object. Engineers do this all the time, especially aerospace engineers. So anyway, go look at the wiki link I’m gonna put below and read up on similitude so you can understand it. I will tell you this. It has something to do with continuum mechanics which is by far the hardest course I’ve ever taken in my life. So if you must know there’s a city in Florida named Destin, and the thrift store there is the coolest place on earth for me personally. Anyway next week’s video will blow your mind. It’s really complicated but it’s really interesting, so if you can understand it you’re doing pretty good, but it blew my mind. It’s gonna blow yours too.
Have a good one, and get Smarter Every Day. [ Captions by Andrew Jackson ] Captioning in different languages welcome.
Please contact Destin if you can help.

Eugene Islam

100 thoughts on “Helicopter Physics Series – #3 Upside Down Flying With High Speed Video – Smarter Every Day 47

  1. I just bought a coaxial helicopter and i can't even control the lift and pitch at the same time.How the hell does Carl control so many things without getting it all mixed up?

  2. Glad I went back and watched part two again – was able to properly comprehend the natures of (and differences between) collective and cyclic pitch and thereby understood and enjoyed this episode much more clearly!

  3. can aliasing happen to the human eyes? ive seen some videos of planes that look like they have completely stop but you can hear them, and ive seen a couple myself, but it doesnt always happen. the part of the video where the propellers looked like they stoped reminded me of the "stationary" planes.

  4. No. Our eyes don't capture static images at a set frame rate and stitch them together. Aliasing happens when the periodicity of a cyclical thing approaches or meets the frame rate of a camera. Our eyes are constantly seeing as long as they're open. Arguably, our brain parses the constant image into a series of chunks so as not to aid in comprehension, but we effectively see a continuous stream of stuff at the speed of light. Unimpeded motion blur is the side-effect of continuous sight.

  5. Tommy Hilfiger? Eddie Bauer? Liz Claiborne? Dickies?? Wait, Ben Davis. *googles* YOUR LOGO IS A CHIMPANZEE?? Dude SWEET

    Incidentally I've sold Tommy Hilfiger a bunch of expensive shit for his kid. He has a brand with his namesake too.

  6. Get a simulator for your computer. RealFlight or Phoenix. Neither is exactly like reality, both help you learn approximately how a real one will react.

  7. What is the explanation for the times when the helicopter staying vertically? what is the counter force in the direction opposite to lift in this case that make the copter stay in a position? 

  8. Wow, I did not know helicopters were capable of this wizardy before this series. However, I also never really understood how choppers worked. This series is helping to clear that up a bit but I think they went into explaining the flippies a little too quick. It would have been nice to see the camera on the chopper of a normal flight (no flippies) to see how the swashplate and anti-torque play a role in normal basic turns and such before jumping into flips and diagonal flights and all that. Not a big deal but it would have made understanding easier.

  9. I am a helicopter flight instructor and gotta give it to you,  These videos are great and really impressive. You're a great teacher,  have a great demeanor and the quality of these videos is really nice. Keep it up!

  10. Your series is very good for explaining basics.¬†I feel that you could have¬†gone one step better to ensure your audience understands the difference between toys and the real thing. ¬†It's important to point out the difference between a¬†hobbyist's 'toy' helicopter and a real one. There is no commercial two-bladed under-slung system available that can fly upside down, to my knowledge, as¬†no "negative pitch" mechanism exists that will permit the rotor system to go into such pitch angles. Multi-blade articulated rotor systems are the same, for virtually 99.9% of all commercially flying helicopters. Yes, one or two of the "Red Bull demonstrators" are aerobatic, but have been specially constructed with¬†multi-blade articulated rotor systems for just that purpose. I've even¬†seen an old black and white¬†demonstration¬†video taken many decades ago (1950's)¬†of a person doing low-level loops in a three-bladed fully articulated system…very dangerous.¬† Some military¬†gunships (AH-64 comes to mind) are capable of some aerobatics¬†(not when fully armed due to weight), and¬†I can assure all readers that an upside-down¬†function is NOT included in their military flight training. I flew¬†UH-1H troop carriers, "C" model Huey gunships, and the sleek¬†AH-1G Cobra¬†gunship, amassing 1,955 hours of combat time.¬† While I¬†can state from personal experience that we put those aircraft right on the line for their fullest flight capabilities, flying 'upside down' or doing any of the flight tricks seen in your videos was not on the¬†list.¬†Any attempt to permit any one of those¬†helicopters to achieve negative weight on the rotor¬†system would result in mast bumping and shearing¬†the rotor system off the mast. Unfortunately, I have actually been a witness to two occurrences of that phenomenon in combat.¬† JCH, Colonel, USA (Ret). ¬†¬†¬†¬†¬†

  11. Another amazing video Destin, helicopters have fascinated me since I was a kid. Although I live in the UK now, I lived in SC when I was a kid and we went to Destin, FL. I remember the amazing white sand on the beach lol. 
    The only real life choppers that can come anywhere close to the R/C model as far as I'm aware of are the German MBB BO105 and the British Westland Lynx, I may be wrong. But I think they'd break a lot sooner than the agile model lol.
    Keep up the great work with the excellent videos. You are really nice to watch and get the information across very well ūüėÄ
    Cheers, Richie 

  12. Came over from Grant's channel 40 minutes ago and I've already watched several of the most fascinating and interesting, not to mention brilliantly presented, videos I've yet to find on Youtube. Thank you : )

  13. I just found this channel and it is amazing. And I agree with you, continuum mechanics is one of the hardest topics I ever studied. Brrrr. In Spanish it is called "mec√°nica del medio continuo", but some people say "mec√°nica del miedo continuo".

  14. So, what he just said is that real helicopters can do this…..why do I imagine drone helicopters being scary as balls now.

  15. The last video in this Playlist was crazy! I don't think I've ever REwatched a clip so many times. Crazy you can even see the pilot almost come out of the cockpit, even his mic and muffs were dangling. Thank God he survived. Thanks for more awesome videos Destin!

  16. I can't for god's sake notice the gyroscopic precession (explained in #4) by looking at this video. As a matter of fact, it looks like it's not off phase by 90¬ļ – it looks like it's increasing lift on the back to move forward, increasing lift on the left to roll to the right and so on. WTH?!

  17. how is the motion of fuel inside a helicopter is prevented, which if not causes continuous shifting of centre of gravity??

  18. Comments disabled on last video. Am I the only one that thinks that helicopter brand is excellent? That crash could have been a lot worse but it broke apart pretty darn safe. I guess every James Bond movie has told me a helicopter is supposed to lose the blade and cut someone in half during every crash.

  19. Should have fixed the helicopter to the ground. So when you power it up, you can see the parts move without having the helicopter fly away.

  20. When the swashplate tilts forward, sure the linkage is pulled down when the linkage is at the front. But, the actual blade is 90 degrees off the linkage, if you view it from the top. So, when the linkage is pulled down the most, the blade is actually on the side pointing to the right or left of the helicopter. How do you explain this?

  21. When Destin mentions rolling shutter at 1:43, then finishes making a video about it 5 years later. It's cool to see that the germ of an idea was already planted here in 2012.

  22. I had no idea how blade movement was controlled. I got Goosebumps when I saw the swashplate and its mechanism in slow motion. Such an ingenious way to control the blades. Do a series on ingenious mechanisms used in such machines.

  23. I had a USMC roommate who swore against helicopters. Told me ever hour of flight cost 2 in repairs. Now i see why.
    Great series, though.

    Much love!

  24. I know it's kinda passe to post on old videos but hey, this is the internet and today this video is new to me.

    I came here from watching an RC helicopter stunt video and thought "I wonder if SmarterEveryDay has slow motion video of RC helicopters?"

    Did a quick search and the rest is quite old history.

    Thank you Destin for broadening many peoples horizons including my own.

  25. I love your videos… and used to fly a 60 nitro RC heli. I currently fly commercial helicopters (Bell, Robinson, etc.) However, I have to admit that having watched this video I can't find ANYWHERE in it where you actually explain what CCPM is!!!

    For readers who are curious, when you apply cyclic forces away from a steady state (neutral) you reduce lift in 1/2 of the rotor disc, and increase lift in the other 1/2. Depending on which way you were going (if not in a hover) and which way you moved the cyclic, that means that the aircraft will either lose overall lift or gain overall lift. That means you need to increase collective pitch so that you won't go up or down… but rather have just the aircraft respond to the cyclic input.

    In an RC heli with CCPM your transmitter tells the collective servo how to compensate for the cyclic stick being moved. So in addition to doing what you want cyclic-wise it adds or subtracts collective pitch.

    This is easy to see during the "cyclic pitch test" prior to flight. An independent cyclic would only alter the blade pitch in one part of the 360¬į arc. A mixed pitch will alter the blade pitch regardless of where the blades are in the arc rotation to "assist" with the collective to "make up" for what the cyclic would rob.

    E

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