AMP Models

[zenrat]

My (petrol engined) chainsaw is an Electrolux.

How do helicopters with no tail rotor control rotation around the Y axis?
With a tail rotor that would do the job.  Without one I presume they apply braking forces to one or other of the rotors?

And while i'm asking questions, with offset twin rotors (Chinook et al) do both rotors have to turn the same way, or do they have to counter rotate, or does it vary depending on the design?

[Wardukw]

Fred the rotor blades are counter rotating which cancels out the torque from a single rotor blade system .
Like a single propeller can cause torque twist,,counter-rotating don't.
The Chinooks rotors do spin opposite to each other.

Without a tail tho I'm not sure how well this little egg shell chopper would fly .

[jcf]

The rotors are coaxial and contra-rotating, just like Breguet, Kamov and early Hiller designs.

[PR19_Kit]

A good question Fred, how DO such choppers change the direction they're pointing?

The Kaman Huskie and K-Max must have the same problem, there not being a tail rotor or directional air jet like those tail rotor-less MD NOTAR series.

[Nick]

I was watching a video of a V-22 in the hover and flying backwards. How do they manage that?

[zenrat]

I was watching a video of a V-22 in the hover and flying backwards. How do they manage that?

Tilt the engines back?

[killnoizer]

Yes . 
And vary the angles of the blades and axles in difficult ways .

[NARSES2]

Yes . 
And vary the angles of the blades and axles in difficult ways .

The engineering must be incredibly complicated ? Is it worth it ? A naive but genuine question.

[PR19_Kit]

The 'props' act just like helicopter rotors in the hover mode, they change the cyclic pitch so the blades provide more lift when they're in the forward part of their rotation.

But I think Fred's right as well, the V-22 that flew at RIAT last year definitely had the nacelles pointing backward at some stage, not a lot, but enough I guess.

[Mossie]

AMP 1/144 747SP SOFIA airborne observatory.

I might be tempted by this one if the price tag isn't huge.

I'd imagine it shouldn't be difficult to convert into a standard 747SP.

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[PR19_Kit]

That looks really good, and interesting too, even if it isn't a Whiff.

The SP fuselage is a REAL pain to try and convert from a -200 etc. 

Don't ask me how I know this...................

[Weaver]

A good question Fred, how DO such choppers change the direction they're pointing?

The Kaman Huskie and K-Max must have the same problem, there not being a tail rotor or directional air jet like those tail rotor-less MD NOTAR series.

Differential collective blade pitch. If you increase the pitch on one rotor but not the other, then that rotor has more induced drag, slows down, and the torque forces don't cancel out any more.

[Weaver]

Yes . 
And vary the angles of the blades and axles in difficult ways .

The engineering must be incredibly complicated ? Is it worth it ? A naive but genuine question.

Depends: if you need a 300 mph helo with a 1000 mile range then it's your only option, so if you're the USMC, yes it's probably worth it. If you're a one-man band company doing heli-tours ofthe Grand Canyon, not so much...

[zenrat]

A good question Fred, how DO such choppers change the direction they're pointing?

The Kaman Huskie and K-Max must have the same problem, there not being a tail rotor or directional air jet like those tail rotor-less MD NOTAR series.

Differential collective blade pitch. If you increase the pitch on one rotor but not the other, then that rotor has more induced drag, slows down, and the torque forces don't cancel out any more.

Yep.  That makes sense.  Thanks mate.

[NARSES2]

Yes . 
And vary the angles of the blades and axles in difficult ways .

The engineering must be incredibly complicated ? Is it worth it ? A naive but genuine question.

Depends: if you need a 300 mph helo with a 1000 mile range then it's your only option, so if you're the USMC, yes it's probably worth it. If you're a one-man band company doing heli-tours ofthe Grand Canyon, not so much...

Ta