Whiffs found surfing

[kerick]

That came to a bad ending. Maybe with today's computerized controls it could be made to work. If a V-22 can fly, maybe this?

[zenrat]

"Unanticipated vibration"

They bolted 4 cannibalised helicopters to a rigid frame and were surprised when it vibrated?
The fact they retained most of the choppers fuselages makes it look amateurish (it looks like something i'd build!) and cheap.  Surely it would have been better to remove the engines and transmissions from the choppers and mount them into properly designed subframes with vibration dampening and isolating fixtures.

[loupgarou]

I am not an helicopter expert, but, apart from the vibrations, shouldn't there have been problems with torque too?
Having removed the tail rotors, how did they hoped to balance the main rotor torque?

[zenrat]

All the rotors would have been turning in the same direction (on double rotor helicopters like Chinooks do the rotors go in the same direction or opposite?).
But because they were all fixed rigidly to the frame there would not have been an overall turning moment.  All torque would have been acting on the chopper to frame fixings.

My first thought when I played the you tube clip was that while they could move the thing in the z axis using the helicopters to provide propulsion would not be as efficient as traditional nacelles.

[ChernayaAkula]

<...> (on double rotor helicopters like Chinooks do the rotors go in the same direction or opposite?) <...>

Opposite.

<...> My first thought when I played the you tube clip was that while they could move the thing in the z axis using the helicopters to provide propulsion would not be as efficient as traditional nacelles.

Would using swivelling nacelles with normal-sized props provide sufficient lift? AIUI, part of the idea of using helicopters for engine nacelles is their ability to provide vertical lift, meaning the airship can carry greater loads. Conversely, using nacelles with props would necessitate a bigger airship to attain the same lifting capability.
It's pretty difficult to see, but if you look closely at the pic on the previous page (most other pics I've found are either too small or at a wrong angle), you can see that all nacelles have little pusher props added behind them.

[jcf]

As Moritz states, there was a pusher prop added to each H-34 fuselage.
No, pivoting prop nacelles would not have been the same as the whole
point was to create a heavylift flying crane, not to simply move the gasbag
up and down.

The concept was sound, the problem was in the design and construction of
the connecting framework and landing gear. The "vibration" that caused
the breakup was not from the helicopters, it was induced into the framework
by the landing gear shimmying as the craft was blown sideways by a wind
gust.

It was quite a big deal on the news up here in the Pacific NorthWest when
it crashed and the follow on investigation also received press in the local
and aviation media.

[zenrat]

...The concept was sound, the problem was in the design and construction of
the connecting framework and landing gear. The "vibration" that caused
the breakup was not from the helicopters, it was induced into the framework
by the landing gear shimmying as the craft was blown sideways by a wind
gust...

Presumably something they hadn't foreseen when they stressed out the framework.
Good that they published the results of the investigation.

[PR19_Kit]

...The concept was sound, the problem was in the design and construction of
the connecting framework and landing gear. The "vibration" that caused
the breakup was not from the helicopters, it was induced into the framework
by the landing gear shimmying as the craft was blown sideways by a wind
gust...

Presumably something they hadn't foreseen when they stressed out the framework.
Good that they published the results of the investigation.

Maybe they stressed it out OK but failed to do a vibration investigation and test?

That can bring up all sorts of unforeseen problems at times, as I know to my cost................. 

[Old Wombat]

Why use helicopters?

Unless you want to use up obsolete airframes, why not a rigid airfoil dirigible with a recessed cargo gondola underneath with 4 x V-22 style engine nacelles on wing extensions?

That way you get the dirigible taking most of the load off the engines for lift & adding lift when the craft is in forward flight?



PS: If I remember correctly, if you have multiple engines set around a common axis & all are turning in the same direction, then the torque is transfered into an opposite rotational force around the central axis (ie: if the rotors are all turning clockwise, then there will be a counter-clockwise force exerted around the central axis).

PPS: You need an even number of engines, too, to counteract each other, as an odd number of engines means there is an imbalance of torque, which causes the same effect.

[jcf]

Why use helicopters?

Unless you want to use up obsolete airframes, why not a rigid airfoil dirigible with a recessed cargo gondola underneath with 4 x V-22 style engine nacelles on wing extensions?

That way you get the dirigible taking most of the load off the engines for lift & adding lift when the craft is in forward flight?

Why use helicopters?  Umm, it was Frank Piasecki, what else would he use? 

The project was on a shoestring, a private concept that received a small amount of funding from the United States Forest Service,
along with an ex-USN dirigible bag. The whole idea was to build a flying crane for logging, not a long-range cargo hauler
so the expense of designing and building an airfoil shaped gasbag would have been wasted as the gasbag was there to assist the
rotors, not the other way round.

A sort of competing concept was the CycloCrane:
https://en.wikipedia.org/wiki/AeroLift_CycloCrane

[Old Wombat]

Yeah, but, to me, the conversation seemed to have gone beyond the original concept into further development of it.

It's actually quite an attractive idea, except that you have to find somewhere to house the things.

[pirx]

   
                                       

http://anime.geocities.jp/saitamaev/gareki/tsr2/tsr2.html     

                                               

[Gondor]

So that's what it looks like in that set of markings, nice 

Gondor

[Captain Canada]

Very nice ! Super sleek and clean that.

[zenrat]

Wouldn't ESA markings have been more appropriate?

Looks good though.