Heavy load lifting with multiple Chinooks/CH-53s?

[Mechta]

Given that the prospect of West coming up with a helicopter significantly larger than a CH-53 or a CH-47 in the near future is most unlikely, and the West's relationship with Russia, home of the Mi-26, could be frosty for some time to come, the maximum capacity for heavy lifting is going to remain more or less static for the foreseeable future.

Using more than one helicopter on a single load immediately multiplies the lifting capacity, and has been done with small helicopters (MD-500s (see video from 01:45)), so is it feasible with the West's heavy lifters??

A bit of Googling came up with a some videos, technical reports etc. but nothing to suggest actual experiments with large helicopters.

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1971 proposal by Piasecki to join two CH-53s (not a multi-helicopter lift, more of a new design): http://www.dtic.mil/dtic/tr/fulltext/u2/743516.pdf

Paper comparing dual lifts with and without a spreader bar (includes trial with two R-MAX unmanned helicopters): http://uarc.ucsc.edu/flight-control/conduit/papers/AHS_2014_Berrios.pdf

What additional problems would there be with larger helicopters, and is two the limit? If the lifters were unmanned, would swarming software be appropriate to control them?

[atakacs]

Interesting question hope some experts will chime in

[Fareastdriver]

Whatever has to be lifted has to be brought in by a truck. Maybe quite a big truck but if it is too big or heavy for the truck you can't get it to where it has to be lifted from.

You can hook twelve tons onto a CH47; it is very difficult to justify any system that can lift more than that.

[krypton_john]

Wow, there's something about the idea that gives the gut feeling that any small problem will be increased exponentially... like one small problem on one machine will see both destroyed in mid-air, as any loss of lift would draw them together very quickly.

[The Sultan]

The Piaseki disaster.

https://www.youtube.com/watch?v=_7jENWKgMPY

Nuff said.

The Sultan

[Mechta]

The Sultan, The Piasecki disaster was down to poor engineering of the frame which attempted to link everything rigidly together. To cite that as a reason to not try a totally different idea does not make sense to me.

The extra hazards of a multi helicopter lift are clearly evident, which is why flying the helicopters remotely and using software to control their relative positioning would seem the way to go.

Ship to shore movement of heavier military equipment is the obvious application, where cliffs or a rugged shoreline rule out landing ships and hovercraft. There are plenty of civil applications, although breaking down into single helicopter lumps is likely to be more cost effective for most.

Fareastdriver, Chartered Mi-26s were used in Afghanistan, so someone must have felt the extra lifting capacity was worth buying in.

[The Sultan]

Mechta

Yes the Piasecki incident represents one failure mode: Air Resonance. It is though an example of tying multiple helicopters together. There are so many other failures with rigid connected or independent suspension that will result in the same outcome. Your video shows just how low a pilot's IQ has to be for the technique to be used. What happens when one of a set loses an engine and pickles the load? It is easy, the others are screwed. One note: helicopter hook structures are design for primarily vertical loads, not a 50% lateral load if someone is stupid enough to connect long lines directly to a single load point.

The Sultan

[whoknows idont]

Sultan, both issues could be solved by using a spreader bar and coupling the emergency releases of both helicopters.
I still agree that it makes a complicated and dangerous operation even more complicated and dangerous.
And despite of uncle Rasputins latest adventures, there should still be the odd Mi26 available if really needed.

[JohnDixson]

Sultan,

The lateral load issue is resolved through the use of a spreader bar.

The engine failure case is resolved via linking the hook release systems. The old fashioned way thru wiring through the spreader bar or nowadays, thru a radio link.

Another technology that has been flown is a Load Stabilization routine within the AFCS or FBW system-that would be an asset for a future twin lift project. Funded by the Army and flown quite successfully on a CH-54. Being Army funded, that technology was handed to Boeing for their HLH design.

Remains to be seen if potential users can identify enough loads to justify the design/qualification expense.

[hueyracer]

Don´t underestimate the effect of the rotor-systems on each other......you would never be able to lift twice the load...

Plus those "spreader bars" will add significant weight to the whole construction...

[ATN]

Long time ago I have seen a pic -I can't remember which mag, Flight International, maybe, of two large russian helicopters lifting together a huge pipe line section. The pipe was so long that the separation between the 2 ACFT did not seem to be a problem. I guess this required a flawless synchronization.

ATN

[RVDT]

Don´t underestimate the effect of the rotor-systems on each other......

Care to elaborate?

I have seen this done with 2 x MD500, 1 x MD500 + 1 x AS350 and also 2x SA315B.

Two times SA315B placed one fuel barrel on top of another, so accuracy doesn't seem to be an issue.

HNZ, Jim Wilson and Peter Tait - back in the day!!

[Flying Bull]

Has been done with model helicopters....
and a girl!!!!
https://www.youtube.com/watch?v=77uK19KxMuI

[ecureilx]

Flying Bull, The landing (of the girl too.. ) was a bit awe inspiring !! :ok:

[chinook240]

From 1986, someone at NASA did the maths, it's pretty simple stuff really. (Similar to OPs link)

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880010023.pdf

[Fareastdriver]

I notice that there were at least seven previous studies on this subject going back to the fifties and nothing came of them.

Thank God they invented computers.

[Rotor Work]

Interesting about the spreader bar technique.

This machine has a 66 ton payload.

http://www.bbc.com/news/technology-34017183

COMPANY - Aeros (http://aeroscraft.com/)

Regards R W