HM14/360 covering

This is how you use Diatex fabric

In the summer of 2005 I planned to recover my HM14/360 wings. I took the opportunity to share this experience with several Flying Flea fans. It became a small gathering.

We use a fabric of type "dacron". The firm that made the type of dacron I use is DIATEX (situated in France). I hope that these pictures will help you to avoid making the mistakes we did. All mistakes were luckily not so bad. The finished set of wings is a true pleasure for the eye. Euh .. for my eyes anyway.

First I like to give a warning. The liquids used when covering with dacron are not so healthy. Just look at the labels on the tin cans.

step 1: preparing the wood

The "pre-glue" is a handy thing. The glue is used without thinner and is spread on the wood, that touches the fabric, in a few layers (I used two, amount of layers depends on thickness of fabric. I use DIATEX 1500). The handy part is that it can also be used as varnish. So ... no more using varnish and look out that you don't smear on parts that touch the fabric (varnish on those parts prevents a good glue contact). Really easy! Just do whole the wing! Don't forget to varnish the inside of the spars and leading edge during construction. (Jeroen Cooremans in action)

We were working with a few wing parts at once for this step. You can easily use a roller for the leading edge. This type of ribs were not so easy to "varnish" with pre-glue. Note: pre-glue is the same glue we use later. Here it is not thinned. That is all. I hope my Croses ribs will work a bit faster. (from left to right: Eric Foriers, me (Koen), Koen Vermant alias "Koen2", Johan Vermant (Koen's father) at the back Jean-Jacques Legrand)

As you see. We ran for the sun. It was a HOT day! And the glue dried while you were speading it. Not ideal. So we searched a place in the shade. Anyway, try to do this OUTSIDE. The odors of the liquids really take your breath away. Tip: The glue dried while you looked at it in those blue paint-plates (see top picture). We started to use glass jars with tape around them to block the sunlight. It worked! (from left to right: Koen 2, Thierry Brohez, Johan, JJ, Eric)

step 2: placing the fabric on the structure

You first cover the bottom of the wing. This way the joint of the overlap will be placed at the underside of the wing. It is better for aerodynamica, I was told.

I advise to do this with at least two persons. OK, I overdid it. Roll the fabric over the wing and give some play at the sides. Cut and lay the rest of the roll on a clean surface. (Eric started to wear a white hat, JJ a green one. Like I said ... hot day)

This part is why you need two at least. Fix the fabric with staples while you give some tension to the fabric. NOT TOO MUCH! The fabric might get damaged near the staples.

You see that you need many staples. Using not enough staples results in folds in the fabric.

This is the result. Many small folds. Those are really impossible to avoid. Be assured. They will disappear!

step 3: fixing the fabric to the wood

Now you mix the glue with 50 % thinner. When you now add it to the fabric, the thinner gets through the fabric, touches the "pre-glue" and activates it. It begins to flow into the fabric. Perfectly glued. You need to fix the fabric at the sides. JJ is here doing one side. His mask gave him the name "Darth Vador" for that day. Breathing and voice effect were included. ;^)

Following the advise of the DIATEX CD we began to fix the leading edge too. Eric is doing the whole leading edge. In the picture below you can see Hans Engels save the day. He was the only one with experience in covering. He came a bit later, just in time to tell us our mistake. At the front you just need to do a small strip. Not the entire leading edge! Why? Well, this way you are still able to tension the fabric with the hot iron over the leading edge.

step 4: cutting the left-overs away

At first we used freehand cutting. But we found out it is very tough to get a straight line. We started to use a blue talc line that plumbers use to draw straight lines on a wall or floor. (Hans Engels on the right)

You need a special scissors like this one.

You can cut your first wing part like you want. But ... those who are placed next to it, need to have the same line. If not ... you will see it when the wings are assembled.


Some parts are not easy to cut. Just use 45° cuts for the corners.

Even my son, Jonathan (5), did help. He already felt as a large guy when he could wear my Buff. But when he could help removing the staples, he grew even taller. Beware ... if the strip of glue is not wide enough, you will damage your fabric in the next step. The tension will tear the small strip of glue loose. We only encountered this when doing the wingtips. You are warned.

step 5: tension with hot iron

Some firms sell a thermometer to keep the temperature right. You may not go too high. Yours fabric will deform and wrinkle.

We were very lucky to have Hans with us. He didn't trust the meter and made a kind of test-part. Just a jar with the fabric tight on it. Go with the hot-iron over it. If the fabric wrinkles it is too high. We saw it happen here. Luckily not on the wings. The meter was about 50° wrong! So ... I advise anyway to do the same test.

The firm of the fabric will indicate two temperatures (low and high). The first temperature is OK to level wrinkles everywhere. Just let the iron pass over the fabric. You may touch the wood in you want.

Here you even see Hans touching glued parts of the fabric. You can do it ... USING THE LOW INDICATED TEMPERATURE! If you use the high one, you will destroy the glue. This picture is not at the right place in time. Just placed here to show what Hans is doing at the low temperature.

Once the sides are fixed with glue and the tension is done at low temperature, you can glue the fabric on the leading edge and on the ribs. You can see if the glue has passed the fabric onto the wood. You see the wood through the fabric!

step 6: the sides

The sides are now glued. First the fabric is cut at the right length.

The straight parts are no problem at all. Just slide it over the top and fix with thinned glue. Koen2 applies the glue and his father presses the glue through the fabric. This manipulation with the hand is easy and it really helps.

But ... it are those rounded parts that are a bit tougher. If you just lay it over the top, it is fill of wrinkles. You need to cut the flap in small parts. They are overlapping with less wrinkles.

The worst case of this task are the wing tips. You really need that much cuts to get it properly done.

But ... when it is all done, it is beautifull.

Another view on the first finished fabric side.

step 7: the upperside

It basically is the same as for the underside of the wing. Just be sure to make a overlap. At the front, rear and sides. I took the width of the trailing edge as the overlay. At the sides I didn't cover the entire side again. Just made a 3 cm wide strip.

On the places where the overlay occurs you first add some glue to the first layer. Fold the second layer over the leading edge and ...

... fix it with glue. But again, just a strip. NOT THE ENTIRE LEADING EDGE! If you winder "Why?". Well, the tension that you get with the hot iron is not possible if you already had glued the leading edge completely.

Same for the trailing edge. No need to make a smaller strip. Just do the whole trailing edge.

At the sides. Note how much the overlay is. It is not the entire side!

At the trailing edge you have a small problem due to the angles. You need to cut the end very sharp. Doing that ...

... the fabric fits perfectly. To see how the cutting line runs, just use a mark to show where the underside of the wing touches the fabrics edge. You need to cut from there to the point of the wing.

step 8: the second hot iron pass

This time with the high temperature. DON'T TOUCH THE GLUED PARTS NOW! If you would do this step before both sides are covered you create the possibility to bend your wing!

step 9: the reinforcement band

Here you see me adding the reinforcement band. Mine is 5 cm wide. From the same material as the fabric. It is placed so it covers the joint of the fabric at the trailing edge. Some of the band has to go the other side. But it can be just 1 cm. Placing this band on the round wing tips makes a lot of cuts needed. A LOT. My leading edge did not need a band. I already had a overlay of more than 10 cm.

Step 10: protecting the holes

Each hinge or metal part demands holes for the bolts. Those holes need a extra layer to prevent damage to the fabric. I start making a drawing of a circle on the fabric. Use the tools you find to make the shape. I used a roll of tape and a large can.

Just use your special zigzag scissors to cut them out.

I always fold them into a quarter so I could mark the center.

Add glue onto the place

Place the round part (dot over hole) and fix it with thinned glue.

The result is wrinkled. But once dry you can pass with the hot iron at low temperature and all the wrinkles are gone.

When dry, use a soldering-bolt to make the holes. Be sure you start at the right place. That mark in the middle of that round part now comes in handy.

Here you see different types of holes. Those of the bolts. One at the side. Here the wooden hole cannot be used as a template. I simply used that roll again to draw a circle and cut this hole. That complex cut-shape is to make that I can fix the fabric to the insides of the hole of the spar. But ...I learned that is it better to wait with the holes till the tension liquid is added! And that complex hole is better done with a knife. The burned edges are hard and not more easy to fix with glue.

Here you see how I finished the holes in the same area but on the other side. The wood touches the fabric here. The staples are later removed once the glue is dry.

Wings have holes so water or condensation can escape. These holes are at the underside near the trailing edge. I simply used a 2 euro coin as template and fixed the cut-outs like I mentioned above.

Holes were burned in the center once it all was dry.

I found out about another system. It is very easy to use. Just some part you can buy at the airplane-parts shop. Simply remove the yellow glue protector (the glue is a dry type).

Turn it around, place it and use the hot iron to activate the glue. Use the indicated temperature! It works fast and is pretty. But ... it has not the zigzag line. If you are a perfectionist, you want those zigzag everywhere. (I am not a perfectionist...luckily)

step 11: tension liquid or "dope"

Two layers are needed. It is a mixture of dope, thinner and in the first layer some glue. This product really takes your breath. I was surprised by the speed it works. When I was doing the second space between the ribs, the first already sounded like a drum. It is advised to do this while the wing is vertical. It has something to do about avoiding drips on the inside of the wing.

You can clearly see where you have brushed and where not. The brushed part becomes transparent.

Final warning!

You need to dope both sides of the wings quickly behind each other. If you just use the liquid on one side, the forces are that strong they can deform your wing!
I once say a picture of a wing with a strange dihedral and washout. Seemed that that wing was intended as a straight wing! I never estimated it was that strong, that dope.

OK, your covering is done.

We covered for the first time and we did most of the work in two days of 6-7 working hours. After that weekend only the reinforcement bands and the dope had to be placed on four parts. Two parts (rear wing wingtips) still needed all the work.

I like to thanks all persons who were here that weekend.  Guys, it was a joyful weekend. I hope we all learned a lot from the experience.