wonwinglo

Here are some terms and usages,for the many and varied types of control systems in model aircraft,it should prove useful to beginners confronted with a myriad of descriptions on plans and instructions-

SNAKE-This term refers to a plastic tube within which is normally a fluted plastic inner,usually used for control runs whereby there is an acute bend,END FITTINGS are usually self tapping threaded metal CLEVIS fittings but not always,the snake is held in place with tie-wraps at the various formers and exits through the side of the fuselage.

END FITTINGS-take many different forms,usually metal clevis type devices which clip over the SERVO ARM and control surface HORN,for safety they are locked with either a locking nut or a small piece of neoprene tubing placed over the control end.

SERVO ARM-plastic arms which fit onto the servo itself via splined shaft,the horn is locked onto the servo with a small SELF TAPPING screw,arms can take many forms depending on the application,rotary arms lend themselves to incorporating aileron/control surface differential,adjustable arms can also be used for adjusting throttle throws etc.

SELF TAPPING SCREW-Otherwise known in industry as PARKER KALER after its originator,hardened screw which self taps into softer materials,useful tip here is when replacing the screw back off in anti-clockwise direction one full turn thus picking up the original thread.

CLOSED LOOP-system is used when scale fidelity is required,usually two fishing trace lines connected to dual control surface horns,these can either go straight to two ends of the servo arm or to a slave bellcrank within the fuselage itself,various types of adjustment can be incorporated the easiest being two brass collets attached to the servo arm,split pins are placed within the collets and locked up when correct tension is placed onto the control runs.

PUSHROD-control is usually an inner hard balsa rod to which are bound the end clevis fittings via bicycle spokes placed at right angles into the rod.

GROMMETS-rubber/synthetic grommets placed into the fixing holes of servos,these serve to absorb vibration thus not transmitting it to the sensitive servo,ie to dampen,inside the grommet is placed a STAND OFF brass collet,carefully screw down until it just bites against the stand off within the grommet.

BOWDEN CABLE-plastic outer sleeve to which there is a twisted metal inner cable,ideal for throttle runs,the end clevis fittings are screwed onto the inner cable and are thus adjustable.Tip-apply solder to the stranded ends of the inner cable before cutting with bolt croppers.

BELLCRANK-Various types and angles,used for linking ailerons or high set all moving tailplanes on gliders and sailplanes,any application whereby the control function as set at right angle to the servo itself.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/