Mi-24 Flying Without Main Rotor!

Just found a bunch of movies of a Mil Mi-24 Hind handling quite impressively sans its main rotor! Impressive. Most impressive. Can anyone tell if this is an optical illusion as the people on the site have posted, or if it's the real deal from some Russian TVC kung-fu?

Linky

Whilst knowing precious little about helicopter aerodynamics, I can't see how this could be an optical illusion. Not like car wheels seeming to rotate backwards at 24fps. I know 'copters can "glide" after an engine stall, but the main rotor is still turning in a controlled descent, isn't it? Beside's at looks as though this one actually climbs a little after the first turn. Never seen anything like it.

How long before someone claims it as proof that the Russians have anti-grav?

While not being familiar with the Rotor Brake system of a Mi-24,if so equipped, it would not be impossible to lock the rotor at low turbine rpm after which the rotor head would have wing like aerodynamic qualities. It would be very sensitive to rotor blade position as flight characteristics would be adversly affected if both the leading & trailing edges of opposing blades were exposed to flight path. The jet engines would be able to provide enough thrust to maintain forward momentum of a stripped down aircraft especially in pre-existing flight or a shallow dive. If mechanically possible, it would most likely be limited only to an "air show trick" and would not be practical for operational aircraft & line pilots.

It’s stated right on the thread following the video, that this is an optical illusion. It is due to the frame rate being in sink with the rate of the rotors moving, so the rotors appear stationary. You can hear the rotors movement still in the audio.

it almost looks like it could be auto rotation, have been in a 206 when it auto rotated...was not fun and did not seems as smooth a downward descent as this...

and it was a tail-rotor gear box failure that caused us to lose yaw control...lots of fun...kinda like the barrel ride at six flags.

apologies, did not see the optical illusion explanation...video kept pausing to load.

[edit on 16-5-2007 by deadbang]

Originally posted by defcon5
It’s stated right on the thread following the video, that this is an optical illusion. It is due to the frame rate being in sink with the rate of the rotors moving, so the rotors appear stationary. You can hear the rotors movement still in the audio.

Correct answer.



The shutter speed of the camera is in sync with the rotor speed (or a 1/5th multiple of it).



You also notice the slowness of the tail rotor? Also due to the shutter speed of the camera.



Its all an optical illusion guys/gals - but 2 class videos nevertheless

What sealed the deal for me was when a couple things happened. One it turned with out losing and alt and 2 it started climbing vertical from a "hover". Even if you don't completely understand kilcoo's explination any basic understanding of flight physics would prove this video im-possible. Even if you did lock blades which they have tried to do before on some helos you would not be able to stop all forward movement with out if dropping from the sky, let alone climb.

Sorry guys, I obviously didn't see the entire video. Lucky shooting with synchronized shutter speed is most obvious answer.

It appeared like a remote controlled blimp to me.

Originally posted by Darkpr0
Just found a bunch of movies of a Mil Mi-24 Hind handling quite impressively sans its main rotor!

Impressive. Most impressive. Can anyone tell if this is an optical illusion as the people on the site have posted, or if it's the real deal from some Russian TVC kung-fu?

Linky

DarkPro...

Damn man i thought you were more clever then this...

Shall i explain it for you??? It is just the damn shutter time off the Camera that is equal to the RPM`s that those rotor blades make...

Camera`s make 24 frames a second. This thing would do 2400/240 RPM iff that is correct...

Then the equation is simple...

Originally posted by James R. Hawkwood
DarkPro...

Damn man i thought you were more clever then this...

You are aware, then, that this video was posted several months ago?

Originally posted by Darkpr0

Originally posted by James R. Hawkwood
DarkPro...

Damn man i thought you were more clever then this...

You are aware, then, that this video was posted several months ago?

No Darkpro. I didnt knew that.

I am sorry for making that comment.

You just couldnt knew what you know right now so again i am apologising for insulting you.

Hope you can forgive me.

But it is weird to see a helicopter fly without seeing the rotors rotating.

Originally posted by James R. Hawkwood


I am sorry for making that comment.

Hope you can forgive me.

But it is weird to see a helicopter fly without seeing the rotors rotating.

Most definitely. It's a very unnerving video, particularly the first time you see it.

I was researching this because I couldn't figure it out. I heard several people talking about the craft modified with vectoring jet nozzles like a harrier jet. Many even said there was a show on Discovery about it.

The shutter speed theory is very plausible however i believe it would be very hard to sync the shutter speed, because when the chopper rises or falls or hovers the blades speed up and slow down, which would become immediately noticeable. Also the blades seem to rotate slightly as though they are sitting freely.

I am leaning toward the vector nozzles even though I can't find any thing about it online...

reply to post by DaveyD


It's actually quite easy to sync the frame rate. The rotors turn at the same RPM all the time, even while ascending and descending.

Airspeed and altitude changes are actually controlled by the angle of attack of the rotor blades, not the speed of rotation.

Darn, its no longer available.

This get posted every two weeks or what?

Someone had to say it.

cant be an optical illusion because the the rotor is fixed to the heli and only moves with it which suggests a rotor brake, apparently Mi-24 can over using their turbines like AV-8 harrier.

Is it weird then that there are shadows from the blades on the body of the helicopter?

It is a phenomenon known as aliasing, the refresh rate (frame rate) of the video camera is obviously some multiple of the Revolutions per second of the main rotor, or a 1/5th multiple of it like another poster mentioned.

I dunno how anyone could even begin to believe that the rotor locked up.