From Hang Gliding Wiki
Jump to: navigation, search

ADJUSTING THE WOODY VALLEY TENAX HARNESS

Tenax1.jpg

It’s been almost 2 years, since I got my Woody Valley Tenax. After about 400 hours now, there is no question about it, it is a great harness, and I am happy with it. Several pilots have expressed an interest in this, so I’d like to share some tips about adjusting and fine tuning it. My Tenax doesn’t have a pitch adjustment mechanism, just a rope slider on a back plate with a single suspension line. Here is the simplified diagram.

Tenax2.jpg

When the pilot is suspended, the rope does not stay straight, like it would be without a load, it flexes up, or arches. The suspension point becomes higher than the ends of a rope on a back plate, so it forms a stable equilibrium system. In order to change the pitch angle the pilot/harness combo has to slide back or forth relative to hang point. Whatever position the slider stops at, the equilibrium stays stable.


Think of it as of a ball in a bowl. The ball is in a stable equilibrium on the bottom of a bowl. While a metal bar slider needs something to stop it from sliding, which in a similar analogy would be like a ball on a level surface. Hence butt lever mechanisms and such. Just like on any other harness, the first thing to do on your Tenax is to adjust the shoulder straps. The common rule is, in a level position you should feel no pressure on your shoulders, only light comfortable touch, and that is when your arms are extended forward, and your foot are resting on the boot.

Now the leg loops. Make them comfortably tight. It’s a not a sleeping bag, it’s a racing harness. If your leg loops are not tight, your belly is hanging down in the harness, overloading your zipper, your body is not straight, and most likely the harness will bulge up somewhere, because it is deforming. Let alone the flying and landing issues.

Now it’s time to balance it. This means to find your body’s optimal position inside the harness in relation to your suspension point. With your helmet on, go to max head down position. You should be able to get 10-12 degrees head down. In some cases this might not require any special adjustments to achieve. If you are not getting it, that means your body needs to go forward inside the harness. Loosen up the shoulder straps, put something behind the boot to move it forward for an inch or two inside the harness and that way try to figure out how much forward should your body move in order to tilt you for 10-12 deg. Get a piece of a hard foam (the light kind), get the boot out, cut a spacer, a little thicker than your initially calculated thickness, and stick it with double sided tape, like in the picture. (Don’t wrap it with tape yet).

Tenax3.jpg

Note the slanted cut on a spacer. This makes the position of your foot much comfortable. If you don’t need a spacer to move your body’s position forward, make the slanted foam without extra thickness, to fix the foot position only. It takes some experimenting to find the optimal position. You need to position your body the way that the slider travels in the mid part of a rope, when going from optimal head down to level and to slightly head up (thermalling) position. While experimenting, you can have someone mark the positions of a slider on the rope with a marker. For that you need to remove the bungee cord from the zipper sliders on the back of a harness to access the rope from outside (BTW, what a neat feature, to keep that slider slot sealed).

Here is one hint on how to tell if the body needs to go more forward; if you are getting a nice 5-10O head down position for gliding, but you are gradually sliding back and becoming head up because of control input motions, your CG needs to go forward. It is better to fix the body position the way that you are actually getting a little more head down than desired, while experimenting on the ground. Because in the air you will realize, that flying the glider results in a combination of forces that make you rock up and therefore change your static pitch angle.

Now that you have enabled yourself to go head down, it is time to add a little security feature. If you get in the situation, when the bar is ripped away from your hands, you should be able to reach and grab it. Not, if you are dangling with your head low down and the bar is up there somewhere. So you need a head down limiter. I tied a piece of string to the end of a main, on the slider and attached the other end to the front of a plate. It is long enough to let the slider slide back to my optimum head down position, but no more.

Tenax4.jpg

I would make this limiter on every other harness with slider, Tenax or not. It will take a flight or two, to determine if the thickness of a spacer is right. When it is final, wrap it with tape to prevent from crushing.

In my case, when I switched to my new glider, it became necessary to use ballast.(I am 145, and I fly an all carbon RS3.5, optimal pilot weight should be around 160).

So I got 2 sets of ankle weights, 2X5 lbs and 2X2.5 lbs. This gives me a choice of having ballast from 0 to 15 lbs in 2.5 lb increments. I made fasteners to mount them inside the back plate, immediately next to the main, positioned symmetrically, where they don’t interfere with anything or cause any discomfort. It takes a few seconds to put them on or remove. So depending on the flying conditions I can choose the amount of ballast I would like to fly with.

The type of weights I choose is safe to carry in a close proximity to my body, meaning, that in the event of a crash they won’t go flying through my skull, or end up inside of me (like the metal rods or diving weights probably would ). They are compact (good weight to size ratio), soft, durable, and convenient to fasten up securely.

Tenax5.jpg

So far looks like 10 lbs is the most popular ballast for me, followed by 15 and 0. Amongst some other minor things that I have done on the harness probably the boot protection is worth mentioning. I duplicated the removable tail cover, but in leather, and covered it with “Pitcher’s toe” solution.

Fly safe.

Vrezh.


ADJUSTING THE WOODY VALLEY TENAX PART 2/MAKING SOME ROOM FOR TALLER PILOTS

It has been a while since some new info was added to this great article. I find the opportunity to make an update here for further mods to the all discussed Woody Valley Tenax. This might be particularly useful for some people as WV uses a specific size chart with min/max range for every size, or for pilots getting a second hand harness and dimensions are approximate.

I recently got a Tenax 2 (rope slider only) which was slightly off my measurements by some centimeters (cm) shorter. Even though shoulder and leg straps can be lengthened or shortened to further match your body type and measures, getting the correct CG can be a pain even impossible; and this is very IMPORTANT. Adjusting the backplate limiters to the top positions might have some effect but certainly not the desired one, as your CG would still be far ahead from the correct position. As a result, head down position goes to a max angle directly, with parallel hard and head up harder to maintain.

On to the solution.

1. Remove the tail cone and draw a line to the circumference with a marker as below (mine was approx. 4cm from the edge).

Tenax foot cone1.jpg

2. cut around the line with an industrial/heavy duty scissors, or a sharp kitchen knife. The plastic will be cut rather easily especially with the kitchen knife. Do this carefully.

3. Put the larger diameter part over the smaller.

4. Tools needed. You can also use duct tape for a fast solution, or epoxy resin to put the two parts together.

Tenax foot cone2.jpg

4. Result

Tenax foot cone3.jpg

The boot will maintain its shaping purpose of the harness.

Finally relocate both rope limiters on the top positions on the back plate. This is to fine tune the CG. Re-insert the cone in the harness and make all straps adjustments necessary to balance it. A word of notice; It is imperative to have your reserve chute installed while making the balancing adjustments, as the size of the chute and weight addition is considerable.

Hope the write up was and will be helpful for some.

Fly high,

Tasi

Thanx to the great support of WV (Stefano and Marko) and courtesy of the photos. These guys are a pleasure to deal with.