The BIGGEST helico: the MI12!(rarely seen in flight)

[quadrirotor]

The MI12, the biggest never built!! That's two MI6!...Rarely seen in flight!!!

http://www.dailymotion.com/relevance...i12-russe_tech (http://www.dailymotion.com/relevance/search/birotor+/video/x21rf7_helicoptere-mil-mi12-russe_tech)


The MI10:

http://www.dailymotion.com/rabiletre...i10-russe_tech (http://www.dailymotion.com/rabiletresgrand/video/x21rjd_helicoptere-mil-mi10-russe_tech)

The MI26:

http://www.dailymotion.com/rabiletre...-mil-mi26_tech (http://www.dailymotion.com/rabiletresgrand/video/x21eo6_helicoptere-geant-russe-mil-mi26_tech)


The MI6, rarely seen in flight with wings (long range...)

http://www.dailymotion.com/rabiletre...mi6-russe_tech (http://www.dailymotion.com/rabiletresgrand/video/x21ro5_helicoptere-mil-mi6-russe_tech)

[Whirlybird]

Wow!!!!!!!!!!! I saw the Mi-12 in a museum when I was in Russia; amazing machine. But seeing it in flight is something else. Thanks for posting the link.

[MSP Aviation]

Imagine hover taxiing that beast...

[Twiddle]

If you listen carefully you can hear the copilot saying "3,2,1 practise auto rotation, Go" followed by the sound of a fist connecting with a jaw...

What a beast!

Looks an old video, do they still fly?

[Lioncopter]

must have took a week to preflight the bugger!

[[email protected]]

My only comment rhymes with 'clucking bell':)

[mini]

Amazing stuff.

It would be interesting to see the HV chart for the Mi26...

[MSP Aviation]

1500ft and 120kts should be survivable if you're a stick'n'rudder hotshot! :}

[Phil77]

Current issue (August-September 2007) of Vertical Mag coverstory features the Mi26T.
They claim that huge f*** lifts up 44,000 pounds!!! :eek:

[Fareastdriver]

Dunno how true it is but it was told to me by the Boeing people in 1971 after the Paris Air Show.
The pilots of various nations were discussing their aircraft and on questioning the Russians admitted that the certification of the Mi12 had not yet been completed. Just a minor outstanding test, demonstrating its EOL capability.
About sixteen Western jaws hit the floor.
"You've got four engines and you're going to have to dead stick it?"
"Yes, our govenment's got stupid regulations as well."
It is possible that the one that was destroyed was the one that did this. They didn't rebuild it, they probably couldn't find enough of the bits.

[heli1]

As a matter of fact,one wasn't destroyed..both still exist but the second is no longer complete.It is BIG and unfortunately impossible to extract in one piece from its present parking place .

[Smike]

Now that´s BIG!!!

Cheeers,
Smike

[quadrirotor]

Where you could find it!


http://avia.russian.ee/monino/helicopter.html

[Fareastdriver]

Heli 1
I admit I haven't chased the story up since 1971 but the story from the Boeing people is kosher. I had heard that one had crashed so that why I said it was possible. I looked it up on Wikipedia and there it states that there are uncomfirmed reports of one crashing but again that was in 1969 so the timing doesn't fit. Lots of reasons why it did not continue, maybe one was that it could not get a certification.

[NickLappos]

The troubles with the Mi-12 were probably due to the enormous size and the resulting rotor interactions that occur through the natural structural bending modes. The bracing between the two rotors must be very stiff to quell the natural frequencies, which get very low as the structure gets very large.

The Mi-12 is actually two Mi-10 rotors mounted laterally, so the rotor and control problems were already solved (except for the low frequency vibrations.) The simple scaling of a structure will not work, since the deflections go up with the cube of the length, while the strength goes up by the square, and the frequency drops linearly. The Helostat crashed because of these dynamics.

It is a pickle that the tilt rotor folks solved using extremely stiff wings with composite materials. Most likely, these dynamic interactions created a real flight envelope problem that hampered the ability to put the aircraft into use. It is possible that modern computation could help the control system, and modern composite materials could help the stiffness.

[heli1]

The simple reason why the Mi-12 was abandoned is because gearbox/transmission advances showed that a similar payload could be lifted by the more straightforward Mi-26 ,making the more complex Mi-12 redundant.

[Geoffersincornwall]

Managed to get a 45 minute flight (at the controls that is) of an Mi6 20 years ago and I my abiding memory was that it was like flying an ocean liner - heaven only knows what flying that biggy would be like. On the Mi6 each (heated) blade weighed in at the basic weight of a 206! The thing was built like a brick sh** house and had the weirdest artificial horizon I have ever seen. When you pushed the force trim release button you could hear (and feel) the solenoids opening and closing under the cockpit floor.

Was seriously impressed.

G

:ok:

[Fareastdriver]

The biggest in 1948 was the Cierva Air Horse. That was a triple rotor, one on the nose and two on outriggers all turning going the same way. The whole lot was powered by a RR Merlin on the fuslage. Probably had similar problems that Nick Lappos was describing and came to an end when it crashed, killing the crew.

[Dave_Jackson]

For those who would like to know more about the Mi-12, here are 5 pages from 'Soviet Helicopters - Design, Development and Tactics' ~ by John Everett-Heath (http://www.unicopter.com/1469.html)

Click on the thumbnail pages to bring up large versions, then click on the large versions to get even larger ones.

____________________________


Nick, your post congers up a wild idea. Want to co-author a patent? :uhoh:

The rotors of the Mi-12 Homer (http://www.pprune.org/forums/1469.html) turn with the advancing side on the inside (breaststroke). It looks like the Interleaving - Landgraf ~ H-4 (http://www.pprune.org/forums/1091.html) rotors also turn inside forward. The Focke Fw-61 rotors turn inside forward. The Kamov Ka-22 "Vintokryl" may have tried both directions of rotation.

The ABC rotors are becoming extremely rigid. In addition, during forward flight the greatest thrust from a blade is when it is located at 90º azimuth. This means that the greatest thrust is over the spar (wing), and this means a temporary reduction in lift and increase in vibration.

Wild idea for Side-by-Side configuration:
Can a segment of the fuselage, which is in close proximity to the passing blade tips, be shaped so that it eliminates the 3% tip loss when a blade is at one (or two) specific azimuth(s) near the spar. Thereby offsetting some of the the effect of the cyclical down-wash on the spar.

Dave

[Brian Abraham]

Daves link contains the statement "Mil recognized, however, that vertical take off characteristics in a side by side rotor configuration are not as good as with a tandem due to greater loss of lift from rotor wash." I would have thought the losses in a tandem set up with the fuselage fully immersed in the wash (and over lapping blades) would have been greater. As Pauline Hanson wouldd say, "please explain". :8

[Dop]

It looks like the sort of thing Gerry Anderson would have dreamed up!

[Dave_Jackson]

Brian;

The Mi-12 has a slightly Interleaving (http://www.unicopter.com/B263.html#Interleaving_Rotors) configuration, which can be seen on the plan view in page 82 of John Everett-Heath's book [above].

It looks like the higher thrust area of blades, which is near the tips, spend more time over the Mi-12 fuselage than over the fuselage of a tandem.

Just a guess.

Dave


http://nauka.relis.ru/25/9808/VINT-2.GIF

[Dave_Jackson]

How little we know about Russian helicopters.

Earlier side-by-side helicopters;

In Russian; http://www.mai.ru/colleges/fac_1/kaf/k102/istotria_files/prf_ipb.htm

Translated into English, hopefully; http://translate.google.com/translate?hl=en&sl=ru&u=http://www.mai.ru/colleges/fac_1/kaf/k102/istotria_files/prf_ipb.htm&sa=X&oi=translate&resnum=10&ct=result&prev=/search%3Fq%3D%25D0%25B2%25D0%25B5%25D1%2580%25D1%2582%25D0%2 5BE%25D0%25BB%25D1%2591%25D1%2582%2B%25D0%25BF%25D0%25BE%25D 0%25BF%25D0%25B5%25D1%2580%25D0%25B5%25D1%2587%25D0%25BD%25D 0%25BE%25D0%25B9%2B%25D1%2581%25D1%2585%25D0%25B5%25D0%25BC% 25D1%258B%26hl%3Den%26sa%3DN

[Graviman]

Dave, the only real reason to do this now would be to get around the need to design a large rotor system. Even then MI-26 proves this is achievable. The biggest problem is the need for the MGB to handle a growth factor squared to the MUAW, while everything else is linear. This is due to the need to keep tip speeds below ~200 m/s, and handle same power so torque goes up.


It is a pickle that the tilt rotor folks solved using extremely stiff wings with composite materials. Most likely, these dynamic interactions created a real flight envelope problem that hampered the ability to put the aircraft into use. It is possible that modern computation could help the control system, and modern composite materials could help the stiffness.


Chinook LCT is an interesting example of the possibilities, although not used to overcome dynamic problems (from comments made here about Noth Sea ops maybe it should be). For something this big i imagine the rotor collective response time would be less than the stuctural period. The collective could trim to cancel out vertical accelerometer signals near hub, mixed in with pilot input. The whole thing starts to say FBW, which the MI-26 now is...

[Dave_Jackson]

Mart,

Remember that the Side-by-Side Mi12 was intended to be a heavy lift transport craft, not a highly maneuverable attack helicopter.
______________________________________

In addition;

The world wants more fuel efficient vehicles.
Boeing is bringing out its 20% more efficient Dreamliner airplane.
Prouty says; "The overall airplane lift-to-drag ratio can be 10 to 30, depending on the configuration, whereas the maximum a helicopter can do is 4 to 6."
Prouty says, "... tail rotor absorbing 10 to 20 percent of the engine power".One improvement is obvious;

http://www.unicopter.com/No_Tail_Rotor.gif

.... and there are many more to come from progressive manufacturers.

Dave

[quadrirotor]

From your post, Dave, it seems we must get rid of rotorcrafts when we need an efficient aircraft!!! :mad: :ugh: :}

[CS-Hover]

or think different .... ;)

http://cmeunier.chez-alice.fr/r_page4b.GIF

http://cmeunier.chez-alice.fr/r_Page31w.JPG

http://cmeunier.chez-alice.fr/r_Page32z.JPG

regards