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Retractable Nose Gear Cable System

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Retractable Nose Gear Cable System

Old 11-01-2011, 04:48 PM
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All Day Dan
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Default Retractable Nose Gear Cable System

I’m trying to work out a pull-pull cable system for a retractable Spring Air nose gear. If I use a quick link type of connection, the cable is forced down and is too short in the retract position. The best I have come up with is the use of ball links which allow the cable to lean towards the servo when retracted providing some slack. What am I missing here? Dan.
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Old 11-01-2011, 07:12 PM
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KC10Chief
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Default RE: Retractable Nose Gear Cable System

Have you tried turning that steering collar around? You might have to make the cables longer, but it might just give you enough length.
Old 11-01-2011, 07:52 PM
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Default RE: Retractable Nose Gear Cable System

Looks like you need to bend the ends of the tiller up 90deg, drill and attach the ball links facing horizontally outwards. Then the cable end can rotate on the ball and stay relatively straight down the fuselage.
Evan, WB #12.
Old 11-01-2011, 08:39 PM
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Default RE: Retractable Nose Gear Cable System

Thank you Evan and Matt. Here is the same installation with a ball link on the tiller arm. When the gear is retracted, the link rotates on the ball and provides the slack that is needed. The steering collar can not be turned in any direction other than it is or else it with hit the retract frame in the retracted position. The tiller is 3/32 steel so it can not be bent. I will look into mounting a block on each side and tapping that. Dan
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Old 11-02-2011, 01:16 AM
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Default RE: Retractable Nose Gear Cable System

Most modellers I know use a steel cable (usually coated fishing trace) & just loop it through the holes in the steering arm & secure it with crimp on sleeves, no quicklinks or ball links.

I then make all adjustments at the other (servo, steering arm) end. - John.
Old 11-02-2011, 07:09 AM
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Default RE: Retractable Nose Gear Cable System

Thank you John. I was heading in that direction. Dan.
Old 11-02-2011, 08:57 AM
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Default RE: Retractable Nose Gear Cable System

Looks like you would get plenty of slack with them attached the way they are, I'd prefer to use captured links, I never liked those snap on ones, I'd worry under stress they'd pop off

I have also used just wire looped through like Boomerang1 suggests, only down side is the wire will show wear and chafing over time

good luck
Old 11-02-2011, 03:34 PM
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Default RE: Retractable Nose Gear Cable System

Your other option is to use nylon monofilament instead of cable. It wont mind being looped through the holes, has automatic 'shock absorbtion' so won't hurt the rudder/steering servo, and really light too. The idea isn't mine, but comes from the early '60's when nosewheel u/c's were a new idea, and steering them even newer...
Evan, WB #12.
Old 11-02-2011, 05:16 PM
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Default RE: Retractable Nose Gear Cable System

OK guys, here is what I came up with. I'll be using the flexible cable looped at the tiller arm and an adjustable link at the servo. I get good alignment when the gear is down and plenty of slack in the up position. Thank you for your inputs.

Here's another question for you. When the retract process is started and the cables go slack, the nose gear will wobble around center all the time. I would like to use a centering spring to keep the gear centered. Have you seen any of these installed?

Dan.
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Old 11-03-2011, 05:35 AM
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Default RE: Retractable Nose Gear Cable System

Typically there is a spring system to keep the nose wheel straight,, This is a small pic, but gives you the idea, in those just a piece of piano wire acts as the spring

Also,
I'd keep the loop much tighter than you have it there, you can se from your pic that the loop has moved to the front side of the tiller arm, if one or even both move there and get stuck during the cycle it could cause sevo binding and posibly you don't get the gear fully dropped in the down position. make sure that loop stays where it's suposed to be.

good luck
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Old 11-03-2011, 06:20 AM
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Default RE: Retractable Nose Gear Cable System

Scale, thanks for the image of the centering spring. I was going to do it in a different way but this is much better. I'll have to improve my tapping skills to get it right. I'll clean up the cable layout in my final install. Dan.
Old 11-04-2011, 12:33 AM
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Default RE: Retractable Nose Gear Cable System

What some guys do is fit a piece of zip tie looped between the two cables.

When the wheel is retracted the springyness of the tie spreads the steering cables keeping them aligned & out of harms way.

It's a great idea but I have never had any problems with the slack in the cables getting tangled. - John.
Old 11-04-2011, 08:56 AM
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Default RE: Retractable Nose Gear Cable System

Dan, what is it you're building?
Old 11-04-2011, 10:42 AM
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Default RE: Retractable Nose Gear Cable System

It's a pusher with a Brison 3.2. Here's an image of the fuselage drawing. You can see that the nose gear retracts forward. That compartment in front of the nose wheel is for the ballast to get the CG to the right position. The empennage is mounted to two booms that bolt on to the wing. There will be a receiver with its own battery pack in each boom along with a rudder and elevator servo. The elevator and horizontal stab will be split in the middle for transportation purposes and bolted together for flying. I have the wing done. The fuselage is taking a longer time just getting the details worked out. Thanks for asking. Dan.
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Old 11-04-2011, 10:46 AM
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Default RE: Retractable Nose Gear Cable System

To help with the cable chaffing problem you can take a small drill bit and slightly round the edge of the holes. Just tip the bit back and forth (fore and aft in your case) while running it in your drill. That will ease the edge of the hole a bit.

Ken

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