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Control Snakes
The best we have been able to find similar to the old Micro Mold, later Chart distributed, plastic type. A simple but highly flexible design with a solid 2mm inner and 3.2mm diameter outer sheath. Length 1000mm and weighing just 11.5g bare. Sold as pairs.
These snakes work with a large range of clevises or adjusters and offer very low friction and binding characteristics. They are made from a polyurethane type material and have a slippery feel not dissimilar to a Teflon surface. You'll be amazed at the tight radiuses they will follow and still allow free movement. For best results the outer should be restrained as far as possible, for example taped along its length or spot glue dabbed.
Supplied with adjustable ball joint (assembled as shown) loose for one end and special tapered large bore snap clevis for the other. An additional four large bore snap clevises are included to make use of those handy remaining snake offcuts which, we advise, never discard. (They also make great Hatch Pins!) Pease note, the ends of the inner of the snake should be firmly inserted 7-8mm into the connection hardware; mark with a pencil line indicator to ensure compliance. Roughen end with sandpaper, secure with cyano/superglue.
Shipped by Royal Mail* in the UK as a 1000mm length in our black twinwall sheathing, usually formed triangular fashion for toughness. Standard Parcel rate... CSHP and CSP
Elsewhere in the world they can be sent Internationally in our flat Wallet of 600 x 400 x 8mm black twinwall going at Packet rate. This is stapled and taped around the external edge for shipping security. Inside, the snakes will be coiled up fairly tightly. Of course they can also be included coiled 'U' shaped inside a 500 x 460mm flat wallet wrapped Mugi Evo kit, effectively post free, if added to the order.... CSHK, CSK, CSHL ,CSL and finally they can be just coiled up and sent in a Large Letter envelope or Jiffy Bag.
Where snakes are ordered curved/coiled then they are best hung up vertically immediately after unpacking to lose some of the curve memory. Recovery from the coiled packing may never be total, but use in a curved situation may be the answer eg: wing ailerons drive. Warming gently will help, for example leaving in the airing cupboard (if you have one). Another sensible shipping way is to include them with your Twinwall order-they sit easily dead straight inside the black wrapping material, along the folded sheet edges adding a negligible weight penalty ... CSHP, CSP, and CSL
If unfamiliar with this type of snake and to determine suitability then please send a suitably (A5) sized SAE for 'Letter' post return and we will include a short sample piece.
Low friction, low slop and light weight!
For experimental findings and technical info on these snakes, read on!
Physical dimensions:
The diameter of the outer sheath part of the snakes is nominally 3.2mm. The inner has a diameter of 2mm and is suitable for an interference fit with the quick snap clevises found in a Mugi Evo hardware kit. The aluminium threaded adjusters found here at Mugi fit nicely onto the end of these snakes and can be secured with a drop of cyano or superglue.
Sticking forces - experimental findings
These snakes are really free sliding and you'll be amazed when you get hold of one just how flexible they are. Until you can physically play with one of these snakes getting across how good they are might take some doing. However, with a sensitive electronic scale, we have found the following approximate values for the sticking force, friction or stiction that these snakes create in use. Although force should be expressed in Newtons, the forces involved here are so small it makes more sense to talk in grams.
Sticking force in a straight line is in the region of 8g per metre run.
Sticking force around a 150mm radius, 90 degree curve then straight line to servo (possible typical wing application - total length of run 300mm) being about 18g
So, for the latter example, if your servo has a torque rating of 800g/cm and you are using a servo horn position 1cm from the rotational centre then you will lose 20g/cm of effective torque - or 3% losses through this snake. Not bad at all!
* Note the tightening of postal regulations makes sending these Control Snakes at Packet rate in the black Wallet now more cost effective, at the penalty of gentle curving in the length.
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