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The Model
Part 1 - Chassis
Part 2 - Tail
Part 3 - U/Carriage
Part 4 - Servos
Part 5 - Electrics
Part 6 - Canopy
Part 7 - Flight Trials
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Analysis
Hornet Version
 
        

 

Scratch Built Collective Pitch 3D Pro Hybrid

The Model

This helicopter is slightly bigger than my previous two hybrids, it is based on the Century Hummingbird 3D Pro head around which is built a custom chassis, very little of the original helicopter is used.

One major difference is the use of a belt driven tail, the original helicopter uses a shaft driven tail which fails frequently, the basis of the belt drive is an aftermarket kit (supplier listed on analysis page)

The chassis is made completely of carbon fibre sheet with support blocks produced from delrin. The tailboom is produced from a lightweight but very strong aircraft grade aluminium arrow shaft.

 
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The main load bearing element for the mechanicals consists of a single horizontal plate.

This carries the battery and receiver at the front, moving backwards is positioned the motor which is underslung below the frame to keep a low centre of gravity. A lower flanged bearing supports the mainshaft between main and taildrive gears. Next comes the jockey unit tailmount to hold th etail boom and above this is space to position a gyro.

Support blocks of Delrin hold this member to the side frames.

 
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Vertical side frames are joined to the horizontal chassis using M2 hex head bolts threaded into the delrin support blocks.

The mainshaft is fixed in position within another delrin support block using JB Weld epoxy. The column has bearings top and bottom to support the shaft making three bearings in all.

On top of shaft supprt block is fixed the servo plate again using epoxy. The servos are positioned flat unlike the orignal 3D Pro.

This image shows the main and tailbelt gears in position above and below the horizontal chassis member

 
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The undercarriage is made up of carbon fibre skids and delrin support struts.

Small pieces of carbon fibre cover the delrin supports.

Not shown in this image is a piece of carbon sheet that fits on top of the undercarriage to accept the ESC and BEC components.

The components are bolted together with M2 bolts.

 
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You can download the 2D drawing completed in AutoCAD Release 14 from the link below.

The drawing is to scale and includes all the templates used to cut, shape drill etc all the components of the helicopter.

Right click the link and choose 'Save Target As...'

Hybrid CCPM V3.dwg

 
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You can download the 3D drawing completed in AutoCAD Release 14 from the link below.

Right click the link and choose 'Save Target As...'

Hybrid V3 3D.zip