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oipigface

Motor maintenance

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MikeDaBike
3 hours ago, Kyri said:

What is the prop size used with this setup?

3 hours ago, Kyri said:

What is the prop size used with this setup?

On 02/03/2019 at 18:27, oipigface said:

 I once spent a whole week in his workshop learning how to fix aeroplanes the FuFix way. 

17/13 aero-naut 

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MikeDaBike

Tony, Wherefore art thou ? 😪

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oipigface
On 04/03/2019 at 20:05, Kyri said:

What is the prop size used with this setup?

Sorry for the delay, Kyri. I’ve just been putting the grease in.

The prop is 17x11

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Kyri
On 12/03/2019 at 15:47, oipigface said:

Sorry for the delay, Kyri. I’ve just been putting the grease in.

The prop is 17x11

I bet that pulls well on 6S. Is it all back together now?

 

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oipigface

Wrong question Kyri. 

Yesterday morning I thought all I had to do was locate the retaining screws in the cradle that carries the fus servos and receiver.  That I did, then discovered that the wiring in the fuselage had worn to breaking point, so I’m having to redesign and replace that. I also managed to snap one of the threaded clevis rods on a pushrod, so that’s got to be rebuilt as well. 

And all I wanted to do was bind the receiver to my new Tx, and put some grease in the gearbox! 

Still, I now know exactly how Tony put it together.

Anyway, it does pull well. Some might say it’s frightening. Engine runs tend to be no longer than a couple of seconds.

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Kyri

Thanks, and when it is assembled again please can you show the arrangement with batteries in place? I imagine its a tight fit! 

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oipigface

I don’t know how much general interest this has, but for what it’s worth, here’s what was wrong with the original installation, and a description of how I made it better. I’ve drawn 3 diagrams. The first two show the original installation, first with the batteries and the cradle that carries the servos and receiver in their correct locations for flight. The batteries are prevented from moving by the joiner, which is behind and BEC and associated wiring in front. The fuselage is almost as full as a fuselage can get forward of the joiner. The cradle is secured with two screws just behind the wing servo connection.

01B3306D-476E-48E0-87C1-95955F3D21B6.thumb.jpeg.e6401eaf6a4fa1f67f74e17f3c7eb7c1.jpeg

If maintenance of the receiver or servos is necessary, the following sequence is used: A Unclip clevises from tailplane, take out the battery pack (the hinge makes this easy), unplug Rx power;  B Take out retaining screws; C Pull or push cradle forward until it is in the position shown in the second diagram. The servos can now be unplugged, and the pushrods disconnected from them as needed. If access is needed to the cradle itself, it’s best to disconnect the pushrods. The cradle can then be lifted out easily.

There are two problems with this. Firstly, the wing servo wires have very little room to slide under the connectors, and they can easily be damaged. And secondly, it is easy for the wires, particularly if they are the twisted variety as mine were, to get tangled with the servo arms as the cradle is pushed back. Quite which of these was responsible for the state of the wires that I removed, I don’t know, but the wires were abraded to the point where two or three of them had snapped, and a couple of the solder joints had given way. The wire used was very lightweight, and so especially vulnerable to wear.

Looking at the first diagram,  it’s clear that there is a large empty space under the joiner and the connectors. So I redid the wing wiring so it all fitted there. I turned the receiver around, made four new leads fitted in pairs with MPX plugs

659185C6-BA60-430D-AAC1-B3F9D1ADF4AB.thumb.jpeg.cb01eb60c648ff502055180002b23243.jpeg

Then I made up two short leads with MPX plugs on one end, and sockets on the other. The plug ends were intended to be glued into the wing saddle aperture, the sockets to connect with the new servo plugs. These connections can be accessed through the joiner aperture, as the next photo shows. (This photo was taken before fitting the plugs into the fus, and before I shrank the heatshrink and potted the connectors.):

5316EB57-B5F4-4912-9343-4357B9D8118F.thumb.jpeg.56c7979cb0638739818eadbb43bc5a57.jpeg

This all fits well into the space under the joiner:

387DD0CD-A257-4918-AFA0-990C810F2F4D.thumb.jpeg.ae91971a3102074a54f388b709fb102c.jpeg

If maintenance of the receiver or servos is necessary, the following sequence is used: A Unclip clevises from tailplane, take out the battery pack, unplug Rx power; B Pull wing servo leads through joiner aperture, and unplug; C Take out retaining screws; D Pull or push cradle forward until it is in the position shown in the second diagram. The fuselage servos can now be unplugged, and the pushrods disconnected from them as before.

With this arrangement, there is no chance of the wiring tangling with the servo arms, and although there is still slight pressure needed to push the cradle past the connectors, it is nothing like what was needed before. If I used the very lightweight wire fitted originally, I suspect the problem could be eliminated completely.

 

 

 

 

 

 

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Kyri

Excellent post, thanks for the detail and pictures.

When I bought my first f3f plane (crashed, nose off etc) I had wanted to electrify it. A good friend of mine suggested I try it on a slope instead (I had never done that before). This suggestion combined with the small space inside and work involved, made me try the slope.

Your post  shows what is involved and I like the way you got the tail servos further back - not easy and very well executed!

 

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