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MarkNovack 02-05-2003 02:46 PM

ZNLine factory: Enigma Building
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It brings me pleasure to invite you to follow along with us at the ZNLine factory as we build up a flock of Enigmas for the upcoming contest season. After the last and hopefully final move for the Belgian factory, we have set up the tables and tools and have started production of prefabricated versions of ZNLine kits. Actually, prefabs have been available, but we are now striving to increase prefab production to meet demands. Anyway, lets get down to business and build an Enigma, ZN style. I shall update this regularly with photos until finished.

About the kit:

We always start with the Classic Kit (pre-sheeted surfaces/pre-cut controls/landing gear/wheel pants/all wood parts/stab mounting system). In this case, our customers have opted for full carbon options.

So, let's get started.

Step one (after inventory and inspection) is to join the wing. A flat surface is absolutely critical here. Our building tables are 3x3" steel square tube topped with 3" thick, non-warping hardwood. We lay the bottom wing saddles out and tape them together, carefully aligning all edges. We then lay out the wing halves, checking the mating surface for a perfect fit. We very gently sand any adjustments to the root to get a perfect joining fit. In five wing sets, only one needed any sanding at all to achieve a perfect center joint. We also mark the location of the servo wire tunnel exit. Here is a photo of the wings being layed together on the saddle and center joint checked.

MarkNovack 02-05-2003 02:56 PM

Glue, tape, and weight the wings
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Once satisfied with the fit, it's time to glue them together. Get the tape and weights and glue. We use 24 hour epoxy, but for this step, even five epoxy is fine. Apply the epoxy to the roots and join the wings. Use enough epoxy to get a nice even bond, but not so much that it oozes all over the place. Wipe the center joint, lay the wings into the bottom saddle and tape together. Weight each half against the saddle and place a moderate weight in the center. Here are two of the wings glued, taped, and weighted.


MarkNovack 02-05-2003 06:03 PM

Time for the Leqding Edge
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OK, the glue on the center joint is dry and we are ready to continue onto facing the leading edge. Remove the weights and tape and get the LE strips.

We use Titebond Wood Glue and plenty of masking tape. Nothing difficult here. Simply bevel the root side of the two LE pieces for a perfect center joint and ensure they run straight down the leading edge of the sheeted cores. Masking tape every 10cm will keep everything straight and ensure a perfect bond. It will take about two hours for the alphatic resin to dry.

MarkNovack 02-05-2003 06:05 PM

One more LE photo
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Just allow the LE to overhang the wingtip for now.

MarkNovack 02-05-2003 08:12 PM

The LE are dry, let's mount the tips.
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OK, with the LE dry, we carried the wings carefully to the band saw where we clipped the LE within .5cm of the wing tip. Now, break out the 80 grit sanding block and carefully sand the LE just even with the tip. Done properly, the sand paper will not cut into the tip at all. The LE pieces each weighed 12 grams when I glued them on, so they sand down auite easily. By the way, everything from the cores and sheets to the wing tips and even the epoxy is weighed to ensure matching lefts and rights.
I took the wing tip block, placed them against the tips, traced the outline onto them and cut them together on the band saw within a couple of mm of the surface. Then just enough Titebond is applied and the tips are taped on. Just a couple of pieces of tape are enough here. We will remove all of the tape at once after this step.After this dries, I will put on the overalls, break out some sanding bars and get things even with the sheeting.

Here are photos of the tips going on.

MarkNovack 02-05-2003 08:13 PM

Another angle
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Tips again.

can773 02-05-2003 10:18 PM

ZNLine factory: Enigma Building
Faster man faster, I am already past that stage on the Enigma :D I need some cool tricked out building ideas for the alignment and engine install process. It will help on the second Evolis as well :D

Oh yes this summer will be fun 2 Evolis and an Enigma all DZ powered!!!! and a fancy new car to carry all my toys to the field!! I cant wait.

robert 02-05-2003 11:25 PM

ZNLine factory: Enigma Building
I doubt if it will help you Chad, but there is a fact sheet on installing F1 and all the alignment, at www.probuild-uk.co.uk

MarkNovack 02-06-2003 05:44 PM

Shape the tips and LE
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OK, the LE and tips are dry and ready for shaping. We sand the tip down smooth first, and then shape the LE. The LE should be sanded to final shape because next comes laminating the center joint. The tips will be final shaped later on. The extra meat on them will help to prevent hangar rash on the final product. Here are a couple of shots of the LE and tips sanded down.

MarkNovack 02-06-2003 05:45 PM

ZNLine factory: Enigma Building
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Another angle.

MarkNovack 02-06-2003 06:00 PM

This takes three days
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OK, now it is time to laminate the center joint. First, sand the center joint smooth. The finger should not know when it crosses the center joint. Also, fine sand with 400 the center portion of the wing at least 12cm from both sides of center. We will lay three laminates per side, each impregnated with 24 hour epoxy, however, we can do two laminates per day because each will be dry enough to feather the LE edge to receive the overlap. The laminates will be 17 cm wide, then 20 cm wide, and finally 23 cm wide. Each layer receives just enough epoxy to bond it to the surface. We use a 2" wide brush and pat the epoxy into the cloth. We measure the center often during the process to ensure that it stays perfectly centered on the wing. Once the entire laminate is bonded, we lay paper towling over it and absorb any excess epoxy. Each layer is 49 gram per square meter cloth. Between laminates, there is plenty of drying time to start on the fuselage.

Here are photos of the laminating.

MarkNovack 02-06-2003 06:02 PM

ZNLine factory: Enigma Building
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Another shot.

MarkNovack 02-06-2003 06:11 PM

Lets prep some fuselages
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After the laminating procedure starts, we have time to get the fuse ready. We start be cleaning up the wing saddle, opening up the engine compartment, and cleaning up the nose. Since we are using the DZ in all of the Enigmas, we will open our engine compartment 16.5 cm from the nose and parallel to the nose, not the wing saddle. Remember, right thrust!!! We leave 2 cm at the front and about 6-8mm side border.

MarkNovack 02-06-2003 06:13 PM

Another shot
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Clean hole. By the way, we use a diamond dust steel cutoff wheel from Dremel. It will not go dull cutting the Kevlar.

MarkNovack 02-06-2003 06:19 PM

Next, clean up the wing saddle.
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The wing saddle will be exactly 1cm wide on the sides, 1.5 cm at the back, and the forward portion simply smoothed and symmetrically shaped. Also, the seam at the back will be smoothed down and will be ready to accept the wing.

MarkNovack 02-06-2003 06:21 PM

ZNLine factory: Enigma Building
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Note the scrap. I wanted to show what was cut away. After the cutting wheel, I used a block with 80 grit on the sides and back and then 400 grit to remove the fuzz that Kevlar always leaves.

MarkNovack 02-06-2003 06:24 PM

ZNLine factory: Enigma Building
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This shot shows the forward portion. Later on, I removed a little more material as directed by the big chief, JP Zardini. No extra weight will be left on this airplane at all.

MarkNovack 02-06-2003 06:32 PM

Belly pan.
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Don't forget to clean up the belly pan. Round the frontal portion, but leave enough for the hold-down screw that will go in later on. Also, open the ducts on the rear on the pan and cut away that landing gear slots which are mold marked on the gelcoat. Again, an 80 grit block along the sides to even them out and 400 grit for the Kevlar fuzzies.

rajul 02-07-2003 12:17 AM

Re: This takes three days

Originally posted by MarkNovack
We will lay three laminates per side, each impregnated with 24 hour epoxy, however, we can do two laminates per day because each will be dry enough to feather the LE edge to receive the overlap.
Mark, is it possible to show a close up of the feathering on the LE ? Thanks......

MarkNovack 02-07-2003 10:28 AM

Landing Gear
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Rajul, I will get some closeups of the leading edge where the laminates overlap upon returning to the factory. Basically, all the feathering process is is that instead of cutting the material where it overlaps, we use 400 grit sandpaper to remove the overhang. This cuts the glass just where it stops being bonded to the surface and smooths it down with the previous layer. Just to clarify, we laminate top, bottom, top, bottom, top, bottom.

OK, on to the gear. This first photo shows the gear plates. The carbon is an option, not included in the Classic Kit. So, I took a shot with both types of plates. They are 3mm ply, light ply and carbon, or aircraft ply for the plain. They shall be installed inside, of course.

MarkNovack 02-07-2003 10:34 AM

Here is our jig for drilling the holes.
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We use jigs for everything in the factory. When we produce prefabricated airplanes, perfect is the only acceptable standard. Jigs ensure that perfection and consistency can be achieved. You will see more jigs as we continue. I forgot one jig photo which is used to capture the landing gear and drill them out. The bolt pattern on it comes from the same CNC routing file as the bolt pattern on this jig.

MarkNovack 02-07-2003 10:47 AM

Glue in the gear plate.
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OK, first fit the plate. It fits inside. The rear edge and sides must be beveled so it fits as flat as possible. However, due to the seam and some carbon weave overlayes, the inside of the fuselage in not perfectly flat so we use a generous amount of epoxy and microballoon. We scuff it a bit with 80 grit on the inside, pour out about a tablespoon of epoxy mix, lay our fitted plate inside and clamp it in place for 24 hours.

I want to mention here that 2 hour epoxy will do fine for these strength critical areas. Even half hour is good, but working time can be to short as sometimes a piece must be removed, adjusted, replaced, etc. However, we use the 24 hour because we are building multiple (five at this time) airplanes, it give a 45 minute to one hour working time, and we move back and forth to different projects, so the cure time does not adversely affect our schedule.

Here is the plate clamped into place. We have a hardwood plate pressing the fuselage flat from the outside and another plate inside pressing the gear plate against that. The epoxy/microballon mix fills all of the gaps around the plate edges and fuselage so that there is very high strength with minimum material.

MarkNovack 02-07-2003 10:55 AM

After it dries.
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Here is where things speed up for a moment. We remove our clamps, feel for a nice fillet around the plate. If there are gaps, then we shall add a bit of epoxy and again let it cure. If the fillet is fine, then we drill our holes. Our jig is properly setup to place the gear exactly in the center of the belly pan gear cut-outs. However, for the homebuilder, remember to fit the belly pan and mark the edges of the cut-outs on the fuselage. No need to open the belly pan cut-outs any more than necessary. Keep things beautiful!!!

It takes just a couple of minutes to drill the gear in the gear jig and the fuselage with the fuse-gear jig. Here is JP drilling the fuselage.

MarkNovack 02-07-2003 11:00 AM

BEFORE enlarging the holes!!!
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Before enlarging the holes for the blind nuts, we fit the drilled gear. This allow small corrections to any misaligned holes. If we drilled the enlargements and fitted the blind nuts first, then the gear holes would have to be opened to allow the bolts to fit. This detracts from a professional appearance. In this case, the jigs ensure that everything lined up perfectly, so we remove the gear and open our six holes on the fuse for blind nuts. Here we are pre-fitting the gear.

MarkNovack 02-07-2003 11:02 AM

And the pair
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Almost time to get back to the wings.

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