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Old Jan 24, 2002, 07:58 PM
GMILL47
Lakewood, CO, USA
Joined Jan 2001
41 Posts
Retract nose gear steering linkup

I have am installing a Spring Air retractable nose gear in a JR B25 and would like to know how most folks install a retractable nose gear and maintain connection to the steering servo. I have several solutions in mind, but if there is a standard way of doing this I'd like to know. I am wondering if perhaps "Golden Rods" or equal are used? Perhaps, another way is a pull pull connection that goes slack when retracted , but if so, how does one assure wheel staying aligned for passing through wheel opening?
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Old Jan 24, 2002, 09:41 PM
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Art Newland's Avatar
Camas, Washington, USA
Joined Apr 2001
13,477 Posts
Greg, I think pull-pull is the most common. Not sure about spring-air but anything I've used in the past had a centering spring to keep the wheel straight while the cables were slack. Art
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Old Jan 24, 2002, 10:12 PM
Registered User
Folsom,Ca,USA
Joined Apr 2001
992 Posts
Pull pull works great and its really easy to set up. A no brainer.

Use a line that doesn't stretch like Dacon or Kevlar.

Dave
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Old Jan 25, 2002, 02:48 AM
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Gordon's Avatar
Braunton, North Devon, England
Joined Aug 2000
3,919 Posts
I assume you'll be using the 600 series Springairs.

Attached is a photo of the noseleg installation in a MiG 15 I'm making.

The noseleg comes with a wire spring self-centring arrangement supplied. I'll actuate the steering with fishing line which, being slightly extensible, will allow some "give" in the lines to help minimise the risk of stripping a servo gear on bumpy ground.

The ends of the nyrod outers are about 1.1/4in aft of the steering crank, and as low in the fuz as I can get them - as close to being on the same level as the crank as possible. The lines go slack on retraction. The steering servo also drives the rudder, and is located alongside the duct in this instance.

The unit is mounted on a U-shaped 1/8in ply plate keyed into fore and aft bulkheads, and has 1/8in ply doublers where the retract unit sits. This makes the plate thicker to improve the grip of the mounting screws, and also raises the main plate another 1/8in from the bottom of the fuz. Also, the doubler acts as a standoff, and permits full retraction, otherwise the steering crank would block the final movement as it came up against the mounting plate. If you use mounting beams, you'll need to notch them for clearance for the crank. You'll see what I mean when you start playing.

Gordon
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Last edited by Gordon; Jan 25, 2002 at 03:18 AM.
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Old Jan 25, 2002, 08:50 PM
GMILL47
Lakewood, CO, USA
Joined Jan 2001
41 Posts
Great replies and nice to have confirmation as well as revelation. Yes my Spring Airs are the 602 and 603 units. In mounting the retract, I forgot about the spiral coil offset inherent in the shcok cushioning done by the manufacturer in the leg, so am trying to decide whether to offset the retract or turn the leg so the bottom out of the coil is centered as it exits the fuselage. This leaves the coil axis at an angle but the bottom leg lines up with the upper leg on center. I had basically decided that the pull-pull would be the simplest and appreciate your picture.
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Old Jan 26, 2002, 02:59 AM
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Gordon's Avatar
Braunton, North Devon, England
Joined Aug 2000
3,919 Posts
Hi Greg

Whichever way you mount it, there'll be a bigger hole than you were hoping for in the underside I just located my retract unit on the centreline to keep things as simple as possible - ie the leg is offset by approx the 1/2-width of the wheel.

For the mains, you'll either have to replace the sprung legs with straight wire, or fit the legs on backwards. Otherwise the coils on the legs supplied will come up against the retract cylinders and leave the legs dangling.

Gordon.
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Old Jan 27, 2002, 09:58 AM
GMILL47
Lakewood, CO, USA
Joined Jan 2001
41 Posts
Update: I put together the Spring Air nose strut into the retract. It did come with a centering wire that is clamped to the rotating block and inserts into the furnished pull-pull belcrank, so the centering issue is taken care of.

On a separate but related note, how important is the helical coil in the strut? I understand it's purpose, but would like to eliminate it. What wire is used in making landing gear? To bend it does one heat it or bend it cold?
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