Farings Rear

This blog covers the finishing up of the factory rear fairings.

Overview
With the painting next the rear fiberglass was finally dressed up and installed with the correct screws along with all those final adjustments.

Installation
The lower rudder fairing lights were connected via a four [4] pin plug mounted onto the first bulkhead after the fin attachment. To do this the cable in the fairing was drawn out and connected to the plug and then feed back in into faring then the faring was secured with a  flat head M3 screws.

The elevator faring were next and again secured with the M3 pan head socket head screws with the rudder stab fairings fixed with flat head phillips M3 screws.

Next was the dorsal fin here a couple of holes were re-established using a hole finder and after a series of adjustments it was screwed to the back of the fuselage using M3 flat head screws.  The connecting cables from the the stab and trim tab had previously been connected and it was a matter of checking and fixing the dorsal fin.

Finally the rudder stab fairings were installed. As these have to be removed at the 100 hourly to inspect my nick in the spar they were fixed using M3 pan head screws with an incorporated washer. The starboard faring required some more modifications at this time as it did not fit a cleanly.

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Note: All Rivet Nuts were re-tapped with a M3 tap to improve screw installation and avoid cross threading  

Fixing holes
Some of the holes had to be relocated, tuned pick a word this is one reason floating nuts exist. When required the correct center was marked onto the surface with a biro in the form of a cross. Next a small amount of Plasti-Bond was mixed and the hole filled then a strip of peel applied across both sides and the mixture squeezed between the fingers and set aside to cute.

When cured the new hole center was re-established and drilled with a 2.5 mm drill before sanding. Once shaped the hole was enlarged with the Dremel motor tool as described previously.

Priming
With this done they were removed and all holes in the fiberglass enlarged to about 3/16'' using a conical grinding stone found in the Dremel kit, this gave a clean hole that could not be achieved with drills. 

All fairings were primed using rattle pack bumper bar primer and left to be sanded just before painting

Comments
With the rudder and elevator stab fairings I would not remove the waste to the factory line just straighten both edges equally on both sides as the extra material would allow the fixings to be installed in a flat area the faring. Allow the faring to lie naturally as mine needs a push and shove to line up as pressure was applied before drilling mounting holes.

Note: Pressure was applied when drilling the hole to flatten out the curve and the movement when tightening up the screws created variability creating hole movement, in fact they fit differently every time if only a little. If riveting consider fixing the lower flange and then drill and fix the upper the upper.

The rivet nuts are a mixed blessing as without them the M3 large head screws could not have been used but they make the installation the holes more difficult. There biggest downside is the hole locations are more critical even with 5 mm hole but I was thinking floating nuts when doing the hole filling.

Pop rivets would be the quickest but there are reasons on this project and screws do allow you to adjust pressure obtaining a neater fit.

Above all make sure you mark out the ribs and spar before drilling.



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Rudder Wrap Up

This blog covers the final assembly of the rudder and fin

Overview
With the elevator stab fitted it was time to reinstall the rudder and fin

Fin Attachment
The front attachment was upgraded to a similar specification as the new model by the addition of two [2] AN3 bolts. These and the original mounting bolt were secured to a series of floating nuts riveted to the original bulkhead, this was done for ease of assembly.

The outer floating nuts were tight at installation
requiring custom fitted bolts

Fin was fixed using a series of AN3 bolts at the
eight [8] factory fixing points

Lower fairing covered in previous blog
Nice small detail using a piece of scrap

The electrical for the top flashing beacon and the trim motor drawn through and connected  under the nose area of the fin with access is gained via removal dorsal fin.

  

The gap between the fuselage and fin was filled using silicon. Masking tape was fitted on both sides and a bead of silicone applied and then smoothed to shape allowing the tape to be removed.                                                                                                                                                                              Painter tape was used to give a fine edge

Rudder Installation
With the fin installed the final task was to fit the rudder. This only required two [2] pivot bolts to be installed and while this had been done before it proved to be a hard task to fit the nuts. 

In the end a washer was tacked with super glue and supported on the spigot on the hole jig allowing the nut to be rotated with enough pressure to engage the bolt allowing a ratached ring end and spanner to complete the task.

Next the rudder cables were pulled through and connected to the rudder horn secured using a D shackle to the horn. 

Rudder horn

Finally the electrical cable for the tail light was connected to the fixed plug inside the fuselage and then feed back into the faring allowing it to be fixed to the underside of the rudder.

Lower fairing fitted

Refitted the rear fairing between the fin, elevator stab and fuselage - this is not a standard factory part.

Bits & Pieces - No 5

This blog covers most of the last small tasks related to the rudder at final assembly.


Rudder Fairing

Tucano Tail

While only a just a little untidy it qualified for a upgrade and it's not a lot of work. 

A strip of 0.020" 2024-T3 sheet was cut, lower rivets removed, strip clecoed into position and rudder movement checked OK.

Once satisfied it was installed and riveted.

Note: The fairing bell mouthed slightly as it 
is really a developed shape and mine was straight but the result was acceptable.

Fairing upgrade

D Shackle

Rudder D Shackles
The factory supplied connection was replaced with a D shackles fixed with a clevis pin and castellated nut. 

This was changed as the original connection did not create a double shear connection but has now been upgraded for the aerobatic kits.




Rudder Adjustment
The top bearing is adjustable laterally to align the rudder mass balance and stab and is has slotted mounts for this task - after nipping one top bolt a blade screwdriver used to lever the rudder into its final location. 

There are two 3.2 mm holes provided to allow a permanent location relative to the vertical  spar.   

Fuselage Gap Seal
The junction between the fuselage and vertical spar has a noticeable gap this was sealer with Selleys Black SolarFlex silicone sealant. Two masking tape verticals wers applied and a bead of silicone added. This was then wiped using a disposable towel and allowed to cure.

First application of sealant
Tape removed after wiping silicone

After curing a second application was applied repeating the technique outline above.

Electrical Connections
The aircraft has been fitted with a white tail  light and red strobe. As an ultralight it cannot be flown at night but as it is in full camouflage it was decided to make myself a little more visible.

The connection was finished using the factory access panel to complete the connection. The plug is mounted on a tang located on the second rear bulkhead. the connecting cable in the fairing has a service loop to allow it to be extracted for servicing as shown below.

Final assembly before electrical testing / painting
The rivets shafts are a perfect match for the rivet nuts bore
and providing a perfect temporary fixing

Comment
Took a long day to tidy up all these small loose ends and others but it is now ready for paint preparation. Once painted the clevis bolts will be fitted, pinned as I want the rudder to be able to be deflected for painting.

Rudder Shims

Drill pilot hole #30 through
Do not trim long tab it is need to hold the
shim during drilling

Enlarge hole to 6.0 mm

Trim using stainless steel scissors
A 2 - 3 mm tap is left on the un-drilled
side and placed against the bearing block
as an anti-rotation tab

Installed ready for caps

Rudder Faring Bottom - Part 4

The D-nose was riveted to the spar at this time but the taper created by the assembly technique for the D-Nose was discovered at the first trail fitting of the bottom faring. If correctly shaped it would have fitted as neatly as the top fairing. 

Options: The first choice was to install it as is but the rudder would have looked like it was bashed with an ugly stick. The other was to modify to achieve the best fit bearing in mind that ongoing modification is the bastard child of change but change it had to be.

Faring Attachment
The start was to install the faring attachment with it running the perimeter of the rudder. This was fabricated from 0.012"" x 2024-T3 to provide addition stiffness. It was installed using the same techniques outlined in the blog on the top faring - click here


To maintain the support at the D-Nose meant that the rudder cable mounting plate would have to be modified. It was decided to move the front edge back to create two horns for the cable to attach too at each side. The front of the faring attachment was pin drilled and file-ed to create a slot for the horns to project through.

Rudder Attachment

Horn attachment

The bracket supplied had three [3] mounting holes at the rear and one at the front however the mounting required the attachment to sit on the two [2] pop rivets securing the lower rib to the spar. 

It was decided to duplicate the mounting holes onto the rudder attachment. A piece of paper was attached to the lower rib and the two rivet heads located. This pattern was then transferred to the rudder attachment and new holes added. These holes were enlarged to 4 mm to ensure a accuracy at the point of attachment. 

The horn was inserted then pop riveted as shown with the front attachment requiring a 5 mm pop rivet [not supplied with kit]

Marking rudder attachment

Capturing Centers

Finished faring and rudder attachment

Note: The faring strip was created in separate components with the joint at the rear. This was not a good idea as it made fitting of the faring difficult as it caught on assembly. It would be better located at the front. 

Faring Installation
The faring was slotted using a 5/32'' chain file as shown to create additional flexibility necessary to align the front edge to the faring attachment. It will be fixed with 1/8'' pop rivets at the front as required to hold the front flange in the correct location. The faring will be fixed as described in the blog on the top faring installation - click here

At the time of installation the slots will be covered with 100 mm wide self adhesive tape.

Lower faring final fit-up
Note: Drain hole located at the base to prevent water buildup

Rudder Faring Top - Part 3

The kit is supplied with two fiberglass faring to for the top and bottom of the rudder. 

Top Faring Installation

Scribe Line

The top faring has to be trimmed to the correct overall height. The factory has marked this with a scribed line on the outside of the skin. This should be filled either with a pencil or felt pen to make it clearer when sanding. The faring was initially sanded on a disc sander until it was about 1.5 mm from the scribed line. 

Top Faring Sanding

It was next placed on a flat surface on a sheet of 80 grit aluminium open cut paper and hand sanded to the line. The final adjustment's were made using 80 grit aluminium cut paper wrapped about a 50 x 25 DAR piece of pine.

Fitting

Marking jig

Trail fitting of the faring showed no issues when installed over the aluminum strips installed previously for this purpose. The faring was taped into position to secure it into it's correct location.

The holes for mounting were pitched at 60 mm using the existing rivets as a guide. Locations were then transferred using a small aluminum jig with a reference line marked with a square. 

It was placed on a rivet center and its center transferred to the faring. The correct location for the horizontal was also transferred to the faring at each location.


The faring was removed and the marked holes drilled 9/64'' and the faring re-installed. The locations were marked with a felt pen and the faring removed to allow the holes to be drilled with a 1/8'' drill. The faring was re-installed and fully clecoed and fixed with 1/8'' pop rivets. 

Note: The holes in the fiberglass were drilled oversize to try reduce pressure slightly when begin riveted.

Fitted and ready to rivet

Rudder Mass Balance - Part 2

Before modification- nose
rib inverted

When the D-Nose was inspected, it was noted that the lower rib was close to the base of the hinge which could have made bolting difficult later. It was decided to invert these at the top and bottom to create more space.

This had a unforeseen benefit when it came time to rivet these to the D-nose as they can now all be supported by hand when drilling as the ribs flanges have a tendency to move away from the drill.

The aluminium faring attachments should be installed at this time.

Mass Balance Skin
The factory skin was formed to a included angle of 80 - 90 deg. about the panel center on a 30 mm OD mandrel [aka the broom handle] putting the initial form into the skin, then hand massaged to suit by rubbing around the edge of the plastic table. The skin was then held in position with both ends placed under the rudder skin and taped into a fixed location.

The first hole was matched drilled and clecoed then inverted and repeated at the opposite side. After a check all top rib holes were marked and drilled after removing the skin. 


The M10 threaded rod was installed with an aluminium tube [scrap fuel tube] to set the correct spacing and secured with an M10 nut. As the flange of the threaded bush is located on the base of the rib, the lower rib was tapered slightly to place the base of the flange just proud of the line of the skin to prevent fouling the rudder stab. 

The skin was re-installed and holes for the spar attachment marked then removed and trimmed using the factory jig and Ofla knife.


Mass Balance Installation.
The M10 nut was ran down to the face of the mass balance but not tightened - The thread in the base was run out and Loctite 222 applied and ran back till the weight bottomed out and when cured the M10 nut was tightened onto the weight.

Finished assembly ready to rivet

Rudder Frame - Part 1

The frame was assembled as outlined in the factory drawings with all parts clearly marked at the factory for reassembly. Once the frame was clecoed together the pre-drilled skin was fitted and clecoed ready to fit the D-nose. No issues were encountered and the skin was pop riveted to the ribs EXCEPT at the last hole, spar and the upper and lower ribs. This is required to undertake the fitting of the D-Nose and fabricating the faring attachments at the top and bottom.  

Rudder frame assembled and clecoed
Ensure all captive nuts are installed before proceding

Fitting D-Nose
The front former's for the D nose were installed for this operation. The D-Nose is supplied as a pre-bent shape, cut to length with cutouts for the hinges. The main task is to match drill it to the skin/spar while in contact with the former's.

The initial fitting required two flat hockey straps 600 mm long with the D-Nose edge's slid under the under the rudder skin. The skin was maneuvered into its correct location after a number of trial fittings. Once satisfied a single hole was match drilled at the top side and clecoed. Then the skin was formed by hand around the nose rib at that location and a hole marked at the other side with a felt tip pen and the D-Node was removed,drilled,re-installed. This was repeated about half way down and finally at the base. 

Note taper

The force applied at the base nose rib created an error that required rework later when the issue created was noted at the trial fitting of the bottom fiberglass faring. [see note]

This will be outlined in the next rudder blog.

The D-Nose was refitted, checked and then all holes from the running down the spar were marked drilled and the D-nose removed and drilled. The edge was trimmed using the factory jig and Ofla Cutter as outline in previous blog. 

The D-nose was refitted with clecos await final fixing.

Note: If doing this again a former based on the inside face of the lower fiberglass faring would be  cleoced into the rudder attachment mount at the base.  The skin would be formed around this fixed reference to the fiberglass faring that has to be installed later. 

Mass Balance
The kit is supplied with a mass balance and associated hardware. It was unclear on the plans if the two attachments were only riveted onto the former, it was decided to integrate the mounts into the rib. This was achieved by enlarging the two 5 mm alignment hole's in the ribs to suit the OD of the fittings. Both bushes were drilled for 4 [four] 1/8'' pop rivets, reassembled and fixed to the rib's.

Fairing Mount Top

The fairing mounts were manufacture from aluminium strip supplied with the kit. The strip was cut to length inserted in between the rib and the skin. The mounting hole center line was marked and aligned through the existing holes in the skin and matched marked using a 1/8''  transfer punch.

A tapered timber backing was used to support the aluminium during the process.

The strip was primed with Grey SLS Etch primer, installed at both side's with cleco's. 

All holes were now pop riveted. The final two rivets at the back required a 1/8'' x  6 mm pop rivet as the factory supplied rivets foul on each other.

Rudder Assembly Phase I