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HelicopterTandem Rotor Craft Chinook - Osprey › Twinn Rexx CH-47, question on wiring
07-08-2008 02:05 AM  9 years agoPost 1
GyroFreak

rrProfessor

Orlando Florida​...28N 81W

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From some one who has built the Twin Rexx CH-47, I need a little help on the electrical connections.

The front and rear diagram calls for pitch (P), elevator (E), aileron (A), but since this is a ccpm swash on each rotor, pitch makes sense, but aileron and elevator don’t. Can someone clarify the A,E,P, servos physical locations, for the front and rear ? I cannot find it on Tech Models web pages.

Also the wiring diagram for the recv to TH-2 define the recv outputs as A, E, P, how does this correlate to my recv (AR7000) as elevator (guess that ones E), aileron (guess that ones A), but P leaves me stumped.. Since rudder and Chan 5 are used, is P an aux channel, if so how is it used ?

Sorry if this should be obvious, but the old grey matter between my ears is not what it used to be.

Here is the diagram I am working from. If you click on it, it should be readable.j

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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07-08-2008 02:59 AM  9 years agoPost 2
cbflys

rrVeteran

Nesconset, NY - USA

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The Twinn Rexx has the servos configured the same for the front and rear. Left Front attach point on the swashplate is Aileron. Rear attach point is the Elevator. Right Front attach point is the Pitch.

The AR7000 receiver uses channel 6 for pitch. Everything else should be pretty straight forward, match the receiver outputs to the TH-2 inputs. The exception will be the rudder (CH4) and CH5 receiver outputs, they will feed into their respective gyros. The gyros will then plug into the TH-2 rudder and DCP inputs.

Follow the radio setup instructions in the manual for setting up expos and DCP, his settings work well.

Also, as you only have one spare channel for gyro gain, you can only use 1 gyro with remote sense. For example, use a GY401 and a GY240. The other alternative if you have two gyros that must use remote gain; you'll have to use a y-connector on the sense leads and hope the same gain works for both gyros. I don't recommend this approach.

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07-08-2008 03:59 AM  9 years agoPost 3
GyroFreak

rrProfessor

Orlando Florida​...28N 81W

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Thanks cbflys,
I finally found the swash data when i started playing around with the TH-2 programing software, exactly like you said. As for the recv hookup your explanation is what I needed.
As for gyros, I will be using two GY240s, so no remote gain hookup needed.
Again thanks for the information and quick reply.
Paul

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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07-09-2008 02:49 AM  9 years agoPost 4
GyroFreak

rrProfessor

Orlando Florida​...28N 81W

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cbflys

I have all the swashs moving in the correct motions, but I a wondering what the 'P' line from the recv does. Is this just the last pulse it uses for synchronizing and ignores it's value (width) ?. I dragged the old scope out and measured all the pulse positions on the AR7000 (with an X9303 xmit) and the following is the pulse positions.
1 Aileron (Beginning of frame)
2 AUX 1
3 ELEV
4 RUD
5 THRO
6 GEAR
7 AUX 2

So should I still uses gear since it is the last pulse for the used ports, or should I go ahead and use AUX 2 since it is the real last pulse of the 7 ports.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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07-09-2008 02:59 AM  9 years agoPost 5
cbflys

rrVeteran

Nesconset, NY - USA

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I'm not quite sure what you're asking, but ...

The TH-2 does its internal processing once it receives a pulse on its 'pitch' input. Remember, the TH-2 is doing the mixing, not your radio - so you shouldn't have any eCCPM mixing enabled. The TH-2 uses the pitch channel to determine the collective position.

JR outputs pitch on channel 6. So that's the channel you should hook up to the TH-2 pitch input.

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07-09-2008 03:05 AM  9 years agoPost 6
cbflys

rrVeteran

Nesconset, NY - USA

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I just realized what you were seeing with the scope. That is the servo grouping. It transmits all the swash channels in sequence. You don't need to be concerned with that. Just hook up the TH-2 to the receiver as specified in the instructions.

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07-09-2008 03:06 AM  9 years agoPost 7
GyroFreak

rrProfessor

Orlando Florida​...28N 81W

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yep, I have all ccpm mixing off and the TH-2 is doing it's job. Since there is no such signal from my recv called pitch, I was confused (pitch to me is same as elevator). The data sheet States it uses the pitch (chan-6) as as the last pulse synchronizing.
Any rate all seems to be working on the bench with both swashes moving correctly.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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07-09-2008 11:37 AM  9 years agoPost 8
cbflys

rrVeteran

Nesconset, NY - USA

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Yea, pitch (in heli radios) is the channel that controls collective pitch. Channel 6 on the AR7000 receiver is labeled AUX1. In mCCPM helis (no radio mixing), the aileron and elevator control the left/right and fore/aft tilt of the swash.

It's these raw channel outputs that the TH-2 uses for its eCCPM mixing for the front and rear swash plates. If the DCP is working correctly, you should also see the front and rear swash plates move up and down about 5mm in opposite directions with elevator inputs.

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07-09-2008 03:31 PM  9 years agoPost 9
GyroFreak

rrProfessor

Orlando Florida​...28N 81W

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AAA-HAAA, as soon as you said "collective pitch" it all made sense. My brain fart kept viewing the 'pitch' as up/down pitch of the heli body which was confusing the crude out of my weak brain cells.
Just a moment while I bang my head on the table a few times !!
.
.
Thanks cbflys for getting that 'pitch' problem unstuck from my head, I have seen the light again !!

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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