RunRyder - How do they fly????

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Tandem Rotor Helis Vertol Chinook > How do they fly????

Low altitude
Heliman
Location: Gouldsboro ME USA

I have a pretty dumb question for you guys in the dual rotor class..I am currently flying a Blade CP and I understand what makes it fly like left and right....How does a heli like the Chinook make its manuevers..looks like they may be quite interesting to fly

Sorry, No frequent flier miles available at this time

03-09-2007 Over year old.

bobkins
Senior Heliman
Location: Bocholt, Belgium

Hi,

The real ones fly forward by lowering the collective on the swashplate at the front and raising the collective at the back. Backwards is the same in reverse.

They fly left by tilting both swashplates to the left. To the right is reverse.

To rotate around the main mast at the front they turn the swashplate at the back to either right or to the left.

To rotate around the main mast at the back they turn the swashplate at the back to either right or to the left.

To rotate around the center the swashplatse are turned to oposit ways

To go up the collective on both swashplates is raised.

The controls in a chinook are a bit different from a normal heli. The collective stick is linked to both swashplates.
The cyclic stick is used to the collective on both swashplates but reversed.
The aileron from the swashplate at the front is controlled by moving the cyclic stick to the left or the right
The aileron from the swashplate at the back is controlled by the pedals ( I am not entirely sure if the ailerons are this way. It may be that the front is controlled by the pedals and vice versa)

On some models this kind of control is used but on other they use 3 servo's for one swash in a ccpm arangement

I hope it made some sense

Greets Rob

Hirobo Shuttle Plus , Trex SE V2

03-09-2007 Over year old.

HOMEPAGE

heli_madken
Senior Heliman
Location: Liverpool, England

Imagine two rotors with CCPM setup just like a single rotor heli, one rotor turns clockwise the other anti-clockwise so torque is cancelled out.

For rudder action for instance tail right the rear swash tilts to the right the front to the left, this means the heli rotates around a central point rather than around a rotor which feels strange at first.

For aileron action for example moving to the left both swashes tilt to the left as a normal heli would

Elevator action is more complicated for example moving forward both swashes tilt slightly forward but the real movement is caused by 'differential pitch' what happens is that more rear pitch is applied than forward causing the rear of the heli to pitch up and then move forward. The differential pitch is controlled via a mixer and monitored by a gyro to stop too much fore aft movement.

Hope this helps

03-09-2007 Over year old.

HOMEPAGE

heli_madken
Senior Heliman
Location: Liverpool, England

Beat me too it just bobkins

I think we both agree!

03-09-2007 Over year old.

HOMEPAGE

bobkins
Senior Heliman
Location: Bocholt, Belgium

Yes I win

But I forgot about the torque so lets call it a tie.

Greets Rob

Hirobo Shuttle Plus , Trex SE V2

03-09-2007 Over year old.

HOMEPAGE

Low altitude
Heliman
Location: Gouldsboro ME USA

Thanks guys, hats off to you guys...it is definatly the coolest aspect of this hobby I have seen. Hope to get good enough at flying to maybe building my own Chinook someday.

Sorry, No frequent flier miles available at this time

03-09-2007 Over year old.

Hooker50
New Heliman
Location: lacey, WA, USA

I've not flown a RC Chinook, but I have flown the 1-1 scale version. A couple of terms I've notice sound confusing to a helicopter guy, me, so I'll clarify them.

Helicopter vs. Airplane terminology:
Pitch = elevator
Roll = aileron
Yaw = rudder
Collective (called thrust in Chinooks) = power

Semantics, I know, but though the application has the same effect, the application itself is completely different.

To expand on what was said earlier in the post, a full size Chinook has 2 stage mixing bell-cranks that effectively take 4 inputs (thrust, pitch, roll, yaw) and combine them to 2 inputs going to both forward and aft heads.

Yaw input alone will rotate the helicopter about the center axis. Though to get the helicopter to rotate around the access of either fwd or aft head will require a combination of roll and yaw input. To think this through, imagine a yaw input. As described before, this will rotate each swash plate in a different direction. Then imagine a roll input where the swash plates move in the same direction. Piecing it together like this is how I remember the mechanical aspect of this maneuver.

Differential pitch is correct. We call it Differential Collective Pitch (DCP) in Chinooks. I’m not sure of the verbiage in the CH-46 communities. Think of DCP as a 1-1 input respective to each head. If you move the cyclic forward, the forward head will decrease the amount of collective input the same amount that the aft head will increase its amount of collective input, and vice versa.

A side note about why Chinooks come to a hover nose up. If it was built to scale, the forward head while the helicopter is on the ground is lower then the aft head. This will cause the nose to pull up when power is applied to become level with the aft head before the helicopter will enter a steady, level hover. Plus the forward transmission (xmsn) is tilted forward 9 degrees and the aft xmsn is tilted forward 4.5 degrees.

Trivial information I know. But hopefully this helps in understanding your models better.

01-09-2008 08:07 PM

doorman
Elite Veteran
Location: E.Berne, NY

1:1 Sounds A LOT Harder!!!!

I read the post from both heli_madken and bobkins, and they both made perfect sense to this "modeler"!!!!!!!

Then I read the explanation from Hooker50 and had to keep reading it over and over.... it is amazing what a word or two can do!!!!!

But Low altitude, you are 100% correct in your observation:

Quote
it is definitely the coolest aspect of this hobby I have seen.

It takes a lot of practice, but worth every bit of it....!!!!

Good Luck On Your Journey to the "Dual Side"!!!!

It is JUST SO HARD NOT TO GET THAT GRIN!!!!!!

If there is a cure for this, please don't tell me about it!!!

01-09-2008 10:10 PM

CH46 CC
Heliman
Location: San Diego, Finally

Hooker50 yes the CH-46 uses DCP, most of the major controls operate the same way on both aircraft.

Doorman, nice body, why did you choose "YR" on your tail and what is your bureau number? I have been with HMM 161 on two occasions for a total of five years. Currently the Marine Corps has approx 190 CH-46 aircraft, I have flown on 143. If your model is based on an aircraft that is still in operation I will check and see if I have flown on it.

My RC 46 is in the hover stage still, not much time to play with it. I can't wait for the time so I can finish the body and go into forward flight.

01-26-2008 04:57 AM

doorman
Elite Veteran
Location: E.Berne, NY

Finish??

Hi CH46CC, sounds as if you should know every rivet on one of these guys!!!! I would like to have a ride in just 1

Actually the finish was done by the original builder and he used a plastic model for the finish and details... I cannot take credit for that!!!

He had offered the info from the plastic kit, but since I was not planning on competing with it, I didn't keep it... sorry...

Thanks,

Stan

If there is a cure for this, please don't tell me about it!!!

01-28-2008 01:21 PM

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Tandem Rotor Helis Vertol Chinook > How do they fly????

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