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Scale P-38 Retract design input.

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Old 03-30-2013, 07:54 PM
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Shadowtech666
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Default Scale P-38 Retract design input.

Hello,

Last week the EAA Museum in Oshkosh let me get slews of photos of their P-38's landing gear. I am in the process of designing my own scale retracts. The object is to have this plane compete in scale competitions so I am going for as close to 100% scale as possible. Thus far, I have this plan laid out (minus a few scale details). I will use a compressible gas spring as well as a standard compression spring to provide a damping action. I've yet to solve for the spring constants and damping constants on the M-S-D system. But question is along the lines of whether my design is similar to the internal structure of Sierra or Century Jet or other well known landing gear manufacturers. The brass-gold looking component is just a bushing to provide proper mechanical action.

I should also mention these are for the Ziroli 114" P-38.

Any thoughts are appreciated.
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Old 03-31-2013, 07:40 AM
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LesUyeda
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Default RE: Scale P-38 Retract design input.

"The object is to have this plane compete in scale competitions so I am going for as close to 100% scale as possible. "

Before getting too carried away, I would do some research into what the judges want for scale competition. I have never seen any go beyond just looking; never into actual function of hardware.

Les
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Old 03-31-2013, 09:11 AM
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Default RE: Scale P-38 Retract design input.


Quote:
ORIGINAL: LesUyeda

''The object is to have this plane compete in scale competitions so I am going for as close to 100% scale as possible. ''

Before getting too carried away, I would do some research into what the judges want for scale competition. I have never seen any go beyond just looking; never into actual function of hardware.

Les

Les,

You are right, the judges only look at what they can see.

The functionality is to provide the proper shock absorption for a 40+ pound plane, not to actually simulate the exact function of the P-38, but it will end up being a really good approximation. One item of interest I consistently seen overlooked are really small details like hinge types, wheel wells, etc.
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Old 04-06-2013, 04:45 PM
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Default RE: Scale P-38 Retract design input.

Robart and sierra just use a spring for dampening
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Old 04-06-2013, 05:01 PM
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Default RE: Scale P-38 Retract design input.


Quote:
ORIGINAL: Shadowtech666
I will use a compressible gas spring as well as a standard compression spring to provide a damping action..........

Any thoughts are appreciated.
Shadow,

It looks great !

All that spring from pneumatic and steel will store energy that will bounce back on the wheels.

You will also need some dampening effect to dissipate that energy, either form hydraulic or mechanical friction.

http://en.wikipedia.org/wiki/Shock_absorber

Consider also the bending effect of the longitudinal forces during touch down, for structural rigidity.

My best !
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