Scale Replica

Scale Model Cars & Helicopters

CSM Smart Carb

CSM's Smart Carb will adjust the carburetor main mixture needle on the helicopter's engine to richen or lean the fuel mixture based on the temperature of the engine's cylinder head.

It works from a temperature sensor placed on the cylinder head and operates via a servo connected to main needle. No extra receiver channel is needed - just power supplied via Y-lead.

This simplifies mixture adjustment, protects the engine against a lean run and also make the mixture less sensitive to temperature changes. All of this will allow higher, more consistent power output.

For this workbench I am going to show how I added this to my Align 600 Nitro Pro. The biggest challenge with this modification is adding an extra servo to the frame to move the mixture needle.

CSM Smart Carb
Written by David Da Costa   
Tuesday, 05 February 2008 17:36

The Build Log

After deciding on the location for the servo I had to fabricate a mounting plate. The first step was to draw it up on the computer, I use Vectric VCarve Pro which also generated the G-Code needed to run the CNC Router that I also built.

Below is a picture of the router, for more information check out http://web.mac.com/dacostad/.

 

CNC Router

 

This is the drawing from VCarve Pro 

 

Smartcarb mount

 

..and here is the real thing after the CNC Router has done its work.

 

Completed SmartCarb Mount

 

Here you can see the plate with the servo in place. I am using a Futaba S3150 digital servo, which is ideal for this application. 

 

Servo mounted

 

The next step was to mount it to the Trex 600 Nitro Pro frame. In this case I have added the Align carbon fiber frame braces (part # HN6066) so I trimmed a little from the top of the front right brace to allow the servo plate to fit.

 

Servo mounted on Trex 600

 

The CSM Carb Smart has now arrived from RealRappptors.co.uk.

 

Servo mounted on Trex 600

 

Below you can see the completed Smart Carb installation. I used a control rod from a Trex 450 which I shortened slightly. 

 

CarbSmart Installation complete

 

For the first flights with the Smart Carb I have it set to a target temperature of 100° C and the gain set at the 50% point which I will probably set to about 75% to allow more servo movement for every 4° C of change in the cylinder head temperature. 
 
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