Replacing the MKIV yaw string - tips

Depending on how you store your glider, your MKIV yaw string should provide many hours of carefree soaring, free from that embarrassing "kluged tape on the canopy syndrome". How long? Anywhere from a few years to many more than I wish (planned obsolescence and repeat business being part of my retirement business model :c). When it's finally time to put a pretty new one up front, it's easy . . .

These instructions are for use if you're happy with the current position of the MK## yaw string. If not, please refer to the new installation instructions available at http://www.cumulus-soaring.com/bumper.htm or http://www.williamssoaring.com/catal...ane-parts.html or from me via email (below).

Please remember MKIVs and QVs make great Christmas presents. Your friends will be reminded of how truly nice you are to them every time they fly!


At or above room temperatu

The MKIV clear base is "V" shaped with pointed end facing forward. Apply masking or wing tape to form a "V" parallel to and close to each straight side of the MKIV base. The taped "V" will serve as a guide to aid in positioning the new MKIV.

With your fingernail or the tip of a knife blade* being careful not to touch the canopy plastic, lift the leading edge of the old MKIV base and pull back to remove. The plastic base with adhesive layer will usually come off cleanly, leaving no residue behind. If the adhesive layer or any residue remains on the canopy, rub with your thumb roll it off cleanly.

*If using a knife blade, catch the tip of the old base slightly above the canopy surface so as to avoid any risk of scratching the canopy.

Clean area within the taped "V" with denatured or rubbing alcohol applied sparingly to a soft clean cloth. Hold the new MKIV by the yarn or by the base edges and use a knife tip to lift the red backing film starting at a rear corner of the base - be careful not to touch exposed adhesive with fingers.. Peel away red backing and then re-apply pointed tip of backing to form a "handle". The pointed tip of the red backing overlapping the rear of the exposed base adhesive about 1/8" or a little more.

Holding base with red backing "handle", and using the taped "V" as a guide, place the tip of the new MKIV base centered within the apex of the "V" maintaining even gap from base to tape on each side - - do not allow MKIV adhesive to touch tape. You get only one chance to get it on straight, once adhesive touches canopy, removal and reapplication won't look nice.

With tip in place, and holding rear of base up at 30 degrees or so with red liner handle, use finger nail or retracted ball pen tip (something smooth)to gently work adhesive down toward rear to avoid bubbles. Red liner can be pulled aft to remove before rear of base is smoothed down. Apply even downward pressure to base for a few seconds. Adhesive gains full strength in 24 hours but is ready for flight immediately.

Do not store your new uninstalled MKIV yaw strings or Quiet Vent kit in direct sunlight or high temperatures (e.g. on the dash of a vehicle) as this will degrade the red plastic adhesive liner making it difficult or impossible to remove (return for free replacement if you've already screwed up).

all the best,

bumper

bumperm at frontier (insert dot here) com
zz
Minden, NV

The MKIV is clearly the pinnacle of yaw string technology. Meticulously crafted, it looks great on my glider. However, it suffers from the same problem I have noticed on all yaw strings I have flown. In flight, it constantly swings off the centerline 10, 20, sometimes even 30 degrees, particularly while thermalling. What’s up with that?

MM



On Friday, November 30, 2012 12:36:29 PM UTC-8, bumper wrote:
Depending on how you store your glider, your MKIV yaw string should provide many hours of carefree soaring, free from that embarrassing "kluged tape on the canopy syndrome". How long? Anywhere from a few years to many more than I wish (planned obsolescence and repeat business being part of my retirement business model :c). When it's finally time to put a pretty new one up front, it's easy . . .



These instructions are for use if you're happy with the current position of the MK## yaw string. If not, please refer to the new installation instructions available at http://www.cumulus-soaring.com/bumper.htm or http://www..williamssoaring.com/cata...ane-parts.html or from me via email (below).



Please remember MKIVs and QVs make great Christmas presents. Your friends will be reminded of how truly nice you are to them every time they fly!





At or above room temperatu



The MKIV clear base is "V" shaped with pointed end facing forward. Apply masking or wing tape to form a "V" parallel to and close to each straight side of the MKIV base. The taped "V" will serve as a guide to aid in positioning the new MKIV.



With your fingernail or the tip of a knife blade* being careful not to touch the canopy plastic, lift the leading edge of the old MKIV base and pull back to remove. The plastic base with adhesive layer will usually come off cleanly, leaving no residue behind. If the adhesive layer or any residue remains on the canopy, rub with your thumb roll it off cleanly.



*If using a knife blade, catch the tip of the old base slightly above the canopy surface so as to avoid any risk of scratching the canopy.



Clean area within the taped "V" with denatured or rubbing alcohol applied sparingly to a soft clean cloth. Hold the new MKIV by the yarn or by the base edges and use a knife tip to lift the red backing film starting at a rear corner of the base - be careful not to touch exposed adhesive with fingers. Peel away red backing and then re-apply pointed tip of backing to form a "handle". The pointed tip of the red backing overlapping the rear of the exposed base adhesive about 1/8" or a little more.



Holding base with red backing "handle", and using the taped "V" as a guide, place the tip of the new MKIV base centered within the apex of the "V" maintaining even gap from base to tape on each side - - do not allow MKIV adhesive to touch tape. You get only one chance to get it on straight, once adhesive touches canopy, removal and reapplication won't look nice.



With tip in place, and holding rear of base up at 30 degrees or so with red liner handle, use finger nail or retracted ball pen tip (something smooth)to gently work adhesive down toward rear to avoid bubbles. Red liner can be pulled aft to remove before rear of base is smoothed down. Apply even downward pressure to base for a few seconds. Adhesive gains full strength in 24 hours but is ready for flight immediately.



Do not store your new uninstalled MKIV yaw strings or Quiet Vent kit in direct sunlight or high temperatures (e.g. on the dash of a vehicle) as this will degrade the red plastic adhesive liner making it difficult or impossible to remove (return for free replacement if you've already screwed up).



all the best,



bumper



bumperm at frontier (insert dot here) com

zz

Minden, NV

The first time I saw one advertised, I thought it was an April Fool's joke. But I was intrigued. Months later I ordered one. Could this be real? Have I been duped? I received it in the mail and have yet to install it but looking at the package I'm still not sure. Then, I read posts like the one that started this thread and I'm still feeling like someone is going to jump out and say, "gotcha!"

On Sat, 01 Dec 2012 14:29:59 -0800, Mike Mike Ground wrote:

The MKIV is clearly the pinnacle of yaw string technology.
Meticulously crafted, it looks great on my glider. However, it
suffers from the same problem I have noticed on all yaw strings I have
flown. In flight, it constantly swings off the centerline 10, 20,
sometimes even 30 degrees, particularly while thermalling. What’s up
with that?

How careful were you to place it on the center-line?

The tighter the curvature of your canopy near the centre line the more
critical yaw string placement is. For instance I think that, on a
Libelle, you need to place it within 5mm (1/4") or better of the exact
centre line, but probably canopies that aren't so sharply curved near the
centre line would make the string placement less critical. I stretched a
thread from the exact top of the fin down to the nose and took a lot of
care that both ends were correctly placed and that it wasn't deflected by
the top of the canopy before marking that line and fitting the yaw
string.

By contrast, I suspect that aligning the axis of symmetry of the
transparent sticky bit with the glider's centre line is more important
for aesthetics than for the yaw string's operation. In any case, by using
pencil marks on masking tape placed before and behind the sticky bit and
taking care, you should be able to align it well enough that errors can't
be seen once the masking tap and thread are removed.

You say the string is often deflected to one side: of course, it should
be tail out in a properly flown thermal turn and dead straight when you
cruise straight between thermals.

If it doesn't do that, it might be that:

1) its mounted off to one side. Check with a thin line as I did to see
if its not accurately on the centre line.

2) you've picked up the habit of flying sideways.

Either could make it hang consistently to one side. Either way you need
to work out what's causing it and correct the problem.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Saturday, December 1, 2012 2:29:59 PM UTC-8, Mike Mike Ground wrote:
The MKIV is clearly the pinnacle of yaw string technology. Meticulously crafted, it looks great on my glider. However, it suffers from the same problem I have noticed on all yaw strings I have flown. In flight, it constantly swings off the centerline 10, 20, sometimes even 30 degrees, particularly while thermalling. What’s up with that?



MM

Mike-Mike,

Each MKIV "high tech" yaw string leaves our shop eager to learn, but obviously young and impressionable - - they do have a tendancy towards having a short attention span and will often display a wild tendancy to go whichever way the wind blows.

After installation, especially during early training it's important to treat your young MKIV gently, they are sensitive. Never sweat at it, unless it's obviously heading entirely the wrong way. It's okay to firmly tell it to "straighten up and fly right".

We are working on providing better pre-shipment training on our end. Until then, if you have a really bad one, you can tape the end down straight before flight to show it what you expect of it. Don't do this often though as you risk breaking it's spirit. Not good.

all the best,

bumper

On Saturday, December 1, 2012 4:05:25 PM UTC-8, wrote:
The first time I saw one advertised, I thought it was an April Fool's joke. But I was intrigued. Months later I ordered one. Could this be real? Have I been duped? I received it in the mail and have yet to install it but looking at the package I'm still not sure. Then, I read posts like the one that started this thread and I'm still feeling like someone is going to jump out and say, "gotcha!"

Gotcha!

A bit of history . . . ever since I saw gliders for the first time in "Popular Mechanics" in the late 50's, I believed they were the prettiest, most sensuous thing man had created to fly.

While getting my glider add-on, I flew in gliders that had tape over tape and old adhesive residue doing an ugly job of holding on a bit of string or yarn. Didn't seem right that something so innately beautiful should be graced by a kluged-on yaw string. Shortly after buying my first glider in '98, a S10-VT, the "MKI" was born and sold only to other Stemme owners.

It was named "MKI" in honor of the Supermarine Spitfire suffix, my English heritage, and my father's 30 years in the RAF. The MKIV yaw string has been refined and improved over the past 13 years, many more times than its MKIV designation would suggest. Only a big change, or a bunch of little ones, warrants a new Mark numper! I believe the current MKIV is about as good as it's possible for me to make, requiring almost 30 steps and numerous special tools and fixtures to craft each by hand.

No joke or gotcha, honest. There are thousands of MK## yaw strings gracing beautiful gliders all over the world. Might sound silly, but I'm kind'a proud of that!

If you buy a MKIV and are disappointed, within a year of purchase return it to me and I'll refund your money plus a dollar for your trouble. I hope no one ever takes me up on that offer.

bumper

On Saturday, December 1, 2012 8:54:16 PM UTC-5, bumper wrote:

We are working on providing better pre-shipment training on our end. Until then, if you have a really bad one, you can tape the end down straight before flight to show it what you expect of it. Don't do this often though as you risk breaking it's spirit. Not good.

For those who appreciate the finer things in life, I recommend a yaw string made of golden fleece. Attach it with a dot of clear silly-con adhesive.

At 04:57 02 December 2012, son_of_flubber wrote:
On Saturday, December 1, 2012 8:54:16 PM UTC-5, bumper wrote:

We are working on providing better pre-shipment training on our end.
Unti=
l then, if you have a really bad one, you can tape the end down straight
be=
fore flight to show it what you expect of it. Don't do this often though
as=
you risk breaking it's spirit. Not good.

For those who appreciate the finer things in life, I recommend a yaw
string=
made of golden fleece. Attach it with a dot of clear silly-con
adhesive.


Have you thought of a fibre optic string for low light situations ,like
cloud
bases

On Saturday, December 1, 2012 5:54:16 PM UTC-8, bumper wrote:
On Saturday, December 1, 2012 2:29:59 PM UTC-8, Mike Mike Ground wrote:

The MKIV is clearly the pinnacle of yaw string technology. Meticulously crafted, it looks great on my glider. However, it suffers from the same problem I have noticed on all yaw strings I have flown. In flight, it constantly swings off the centerline 10, 20, sometimes even 30 degrees, particularly while thermalling. What’s up with that?







MM



Mike-Mike,



Each MKIV "high tech" yaw string leaves our shop eager to learn, but obviously young and impressionable - - they do have a tendancy towards having a short attention span and will often display a wild tendancy to go whichever way the wind blows.



After installation, especially during early training it's important to treat your young MKIV gently, they are sensitive. Never sweat at it, unless it's obviously heading entirely the wrong way. It's okay to firmly tell it to "straighten up and fly right".



We are working on providing better pre-shipment training on our end. Until then, if you have a really bad one, you can tape the end down straight before flight to show it what you expect of it. Don't do this often though as you risk breaking it's spirit. Not good.



all the best,



bumper

Tape that bothersome loose end down. Why didn’t I think of that! Thanks, Bumper. In addition to great products, your customer support is unequalled. I also appreciate learning it’s okay to tell the MKIV to “straighten up and fly right”. Silly me. I thought that’s what it was telling me. Anyway, with that cleared up, now I can concentrate on why my flights are always so much slower that everybody else’s.

Michael

On Saturday, December 1, 2012 5:54:16 PM UTC-8, bumper wrote:
On Saturday, December 1, 2012 2:29:59 PM UTC-8, Mike Mike Ground wrote:

The MKIV is clearly the pinnacle of yaw string technology. Meticulously crafted, it looks great on my glider. However, it suffers from the same problem I have noticed on all yaw strings I have flown. In flight, it constantly swings off the centerline 10, 20, sometimes even 30 degrees, particularly while thermalling. What’s up with that?







MM



Mike-Mike,



Each MKIV "high tech" yaw string leaves our shop eager to learn, but obviously young and impressionable - - they do have a tendancy towards having a short attention span and will often display a wild tendancy to go whichever way the wind blows.



After installation, especially during early training it's important to treat your young MKIV gently, they are sensitive. Never sweat at it, unless it's obviously heading entirely the wrong way. It's okay to firmly tell it to "straighten up and fly right".



We are working on providing better pre-shipment training on our end. Until then, if you have a really bad one, you can tape the end down straight before flight to show it what you expect of it. Don't do this often though as you risk breaking it's spirit. Not good.



all the best,



bumper

Tape that bothersome loose end down. Why didn’t I think of that! Thanks, Bumper. In addition to great products, your customer support is unequalled. I also appreciate learning it’s okay to tell the MKIV to “straighten up and fly right”. Silly me. I thought that’s what it was telling me. Anyway, with that cleared up, now I can concentrate on why my flights are always so much slower that everybody else’s.

Michael


On Saturday, December 1, 2012 5:54:16 PM UTC-8, bumper wrote:
On Saturday, December 1, 2012 2:29:59 PM UTC-8, Mike Mike Ground wrote:

The MKIV is clearly the pinnacle of yaw string technology. Meticulously crafted, it looks great on my glider. However, it suffers from the same problem I have noticed on all yaw strings I have flown. In flight, it constantly swings off the centerline 10, 20, sometimes even 30 degrees, particularly while thermalling. What’s up with that?







MM



Mike-Mike,



Each MKIV "high tech" yaw string leaves our shop eager to learn, but obviously young and impressionable - - they do have a tendancy towards having a short attention span and will often display a wild tendancy to go whichever way the wind blows.



After installation, especially during early training it's important to treat your young MKIV gently, they are sensitive. Never sweat at it, unless it's obviously heading entirely the wrong way. It's okay to firmly tell it to "straighten up and fly right".



We are working on providing better pre-shipment training on our end. Until then, if you have a really bad one, you can tape the end down straight before flight to show it what you expect of it. Don't do this often though as you risk breaking it's spirit. Not good.



all the best,



bumper