Mark 4 Yaw String

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£2.74 (22%)
(£8.13 Exc. VAT)
(2 Reviews)

The MK IV “high tech” Yaw String has a clear turbulator base, synthetic yarn and removes easily with no adhesive residue. This is not your ordinary yaw string. Each yaw string is handcrafted through a 28 step proprietary process under a magnifying glass yielding the best quality and clarity. The base raises the synthetic yarn 0.038″ above the canopy eliminating scratches and reduces static charge.

The yaw string is the most effective, yet least expensive, slip/skid indicator. It is made from a piece of yarn mounted in the free airstream in a place easily visible to the pilot. The yaw string indicates whether the pilot is using the rudder and aileron inputs together in a coordinated fashion. When the controls are properly coordinated, the yarn points straight back, aligned with the longitudinal axis of the glider. During a slipping turn, the tail of the yaw string is offset toward the outside of the turn. In flight, the rule to remember is simple: step on the head of the yaw string. If the head of the yaw string is to the right of the tail, then the pilot needs to apply right pedal. If the head of the yaw string is to the left of the tail, then the pilot should apply left pedal.
More Information

Installation instructions - see video under 'Specifications' tab above

Determine ship's true centerline for mounting the MKIV base and included optional center index dot. A good method is to stretch a string from nose to tail. Tie or tape one end of string to glider nose and the other end to top center of horizontal stab or vertical stab. Stand away from front of glider and sight down string to be sure it’s straight and on center all the way from nose to tail. You may need to lift and move the string from one side or the other where it crests the curve of the canopy. Place a piece of masking tape under string just forward of where you will install MKIV and mark centerline on tape with pen. Move string off to side and clean area for MKIV with denatured or rubbing alcohol and soft cloth (I recommend microfiber). Move string back to center.

Make a paper template guide to insure an easy and accurate installation. Cut a strip of paper approx 2″ (50mm) wide by about 8″ (200mm) long. Position the MKIV base at the center of this strip so that only the curved portion at the back of the base is off the paper (align the two corners of the rounded base with the edge of the paper). Trace around pointed front of MKIV base with pencil (no ink) so as to form a “V”. Cut out “V” with scissors and discard. Place template with “V” cutout under string (apex of template “V” cutout facing forward – open end facing aft). Sight down on template strip to insure it is perpendicular to string, tape ends in place.

Yarn is supplied long, cut length to suit and tie simple overhand knot ¼″ (6mm) from end to prevent fraying. If using optional center index dot (this is the reflective dot located loose in MKIV package) temporarily place MKIV base in template “V” and gently stretch yarn aft. Mark desired dot location with tape on outside of canopy. Dot will be installed on INSIDE surface of canopy.

With “V” template and center mark in place, remove string. Clean inside canopy surface where the index dot will go with denatured or rubbing alcohol. Hold index dot between finders and bend one edge gently away from reflective side to loosen dot from backing (do not crease). Use tip of a clean utility knife, or other small knife blade or sharp tweezers, to lift edge of dot from liner. Then using knife tip or tweezers, position dot before smoothing it down with your finger. Use caution to avoid scratching canopy with knife blade. With dot installed, close canopy.

Hold MKIV base only by edges or yarn and remove the red adhesive liner by lifting a rear corner edge with a knife tip so you can grasp liner and peel it off with tweezers or fingernails. Re–attach about ¼″ (6mm) of pointed tip of the removed liner to the back center of base adhesive to form a temporary “handle”. CAUTION! do not touch the exposed clear adhesive surface with anything but the removed liner or allow yarn to contact it as this will impair the optical clarity of the base. The adhesive is very tacky and once it touches the canopy plastic you will be unable to reposition the base without damaging the MKIV. Steady your hand against canopy and hold base using “liner handle” in position over the “V” template cutout. Maintain a slight and even gap on both sides of the “V” cutout and base. Do not butt the MKIV base tightly into the “V” or adhesive may overlap or touch the paper template.

Okay, the goal is to get it on straight and with no bubbles under the adhesive, take it slow and this will be easy. Touch the pointed end of the base to the canopy first while holding the back of the base up a bit, away from the canopy using the “handle”. Use a smooth object (retracted pen tip etc) to slowly work the base down while watching the adhesive progressively make contact with the canopy, this is easy to see and looks like water between two sheets of glass. Before getting more than half the base attached, and while bending up the back of base to keep it off canopy, grasp rear of base by edge corners and gently remove the red liner “handle” by peeling off ( twist “handle” slightly and pull in line with canopy surface, not in line with base surface – – so as not to stretch adhesive). Work remainder of base down. With finger, firmly press base down for several seconds. You may fly immediately, but please don’t wash or disturb the MKIV base for 24 hours to allow full adhesive strength.

After several years of exposure you may wish to replace the MKIV as the yarn wears or fades. To remove the old base lift edge and “roll off” with finger pressure. Or use a fingernail, knife blade, or similar tool to lift an edge of the clear plastic top layer using caution not to touch canopy with any tool. Grasp edge of base with fingers or needle nose pliers and slowly peel off. Any remaining adhesive residue will cleanly roll off with finger pressure.

Customer Reviews
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2 Reviews:

Mark 4 Yaw String
19 June 2023  | 

Fitted first time to my DG800A and was very impressed how sensitive it was. Purchased a second time for another glider. The base is a clear small preformed plastic which doesn’t hinder or distract your vision. Excellent.

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Mark 4 yawstring
27 October 2022  | 

this arrived with the usual speed of all Navboys orders . It sits neatly and tightly on the canopy with the 3m clear triangle and whilst not a criticism I shortened the red wool by a few centimeters , tying the end again

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