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.

Dorsal Fin

This blog covers the dorsal fin install

Overview
The fin installation was covered in the blog on Stab Faring leaving the final task of securing the fin to the air-frame.

Installation
The holes drilled in the previous blog that secured the dorsal fin with 3/32'' clecos were all enlarged to 5 mm and fitted with Countersunk thin sheet M3 rivet nuts. These allow the dorsal fin to be screw flush with the skin of the aircraft unlike the large flange type supplied with the kit.

Note: All these specialized items were purchased from Fastener Kits Online in Australia

Rivet Nuts installed in previous 3/32'' holes

Note: the large head rivet nut was installed in error and replaced

Fixing

M3 Wafer Screw

Fixing is always a issue with cheese head screws chunky, countersunk are not a practical option and the fin has to be removable for heavy maintenance, pop rivets are not a option.

Having used wafer washers previously, a quick search on the net located a supplier in China who supplies these screw in a bag of a 1000 M3 x 12 for $24 with free but very slow postage.

Wafer head screws fitted to port side

The screws have a profile similar to a 3.2 mm pop head rivet and using a 3.5 mm mounting hole allowed the dorsal fin to be secured tightly to the fuselage skin.

Profile Modification
The top edge of the dorsal fin had a flat edge and while filling the side faring with dry macro the excess was applied to the top edge and once it reached the plastic stage the application was adjusted by hand to resembled a radiused edge. Once cured a combination of 80 / 120 / 240 grit aluminium open cut paper were used to achieve a final profile. The rough edges were filled with blade putty and sanded with 120 / 240 aluminium open cut paper to a smooth profile.

Comment
Happy with the final result with the screws working as well as hoped.

Stab Farings

This blog covers the installation of the intersection fairing for the elevator and rudder.

Installation

Trial fit of the rudder and elevator stab fairings
Note: Components have been trimmed to factory guide lines

Trial fit of fairings

Both factory supplied fairings were trial fitted onto the starboard side but the builder could not work out how the intersection was to be created. 

The factory replied that the fin fairing was installed over the elevator fairing but again an acceptable method of assembly could not be found.

After much thought it was decided that the best way forward would be to make the components fit by placing the rudder fairing under the elevator fairing.

Work started on fixing each component onto the airframe before undertaking any modifications.

Masking tape was applied over the areas to be marked allowing an installation scheme to be developed and with rivets securing the skin to the ribs on the same line care was required not to drill at or near a rib flange. This issue arose at the lower side resulting in two broken drills

It was decided to install the mounting points on the rivet line for the rib starting at the nose rib centering about rivet group [pitched @ 30 mm], then pitching the other holes at 90 mm along the top side. The location off the holes in the fin is a projection of the location of the holes on the elevator. 

Ruler

With all the marking out the most useful tool proved to be a cardboard ruler. This was made from a piece of scrap cardboard with a base at 90 degrees and pitches at 10,15,20,30,40 and 90 mm.

The bottom side was more difficult but in general the same philosophy was followed but with a slightly more uneven distribution based on the restrictions created by the rivet locations on the underside.  

Fixing point currently selected with all parts fixed with 3/32'' clecos
Underside shown at the top of image

Note: Do not attempt to drill in the area of the skin line seen running through
the hole without a cleco - it intersects with the stringer and just breaks drills
This single line defines were the fixings cannot be installed

Marking out the port side using the starboard fairing - rivets on nose
ribs located on rib rivet center line

Note: Approx location of the rivets [circles] - location is
about rivet group center seen in gap between to tape runs.

Stab clecoed to turtle deck at a pitch of 90 mm
starting at the nose

Intersection of elevator faring was cut to allow it to be brought into contact
with the fin faring, this area is glassed with 100 mm tape x 5 layers

Note: Two [2] 1/8'' clecos installed to hold the loose components
onto the fin faring

Comment

All the trimming used a Dremel motor tool with a extension shaft with a quick change plastic disc. It was found that discs marked for plastic set at about 15000 rpm gave the cleanest cut.

Sanding was all done using 80 grit aluminum open cut paper and a flat hard sanding board.

Rudder Stab - Part 4

This blog cover a small modification to the stab attachment

Stab Install
With the elevator stab installed the rudder stab was next. Once mounted on the back of the fuselage the builder was confronted with the re-installation of the front mount and it bolts - put simply there was not practical way to install the nut.

It was removed and a AN4 floating nut installed then fixed with 3/32'' counter sunk pop rivets.

Rudder Cable
The rear openings for the rudder cable were enlarged in the rear of the fuselage - the stab post was modified to match.

Modification to provide additional clearance for the Nico Press crimps

Comment
Rudder stab is now functional complete

Rudder Stab - Part 3

This aircraft is to be fitted with a red beacon located at the top of the rudder stab and a Aviolight beacon was selected based on its low weight of 40 grams and compact dimension's.

Red Beacon

An ABS plastic former was machined and glued into the factory supplied fiberglass tip. It was hoped that all it would require is a small amount of filler to be finish it off - this was not to be the case.

With the ABS former in place, automotive filler was added, then sanded with 60 grit painter's paper wrapped around a dowel. Additional filler was added and the sanding repeated then repeated again. The images of this process are to ugly for public publication so I restricted images to the final product which was the goal.

Fitting to Stab
As all the other faring fitted with little effort it was anticipated that this one would be no different - WRONG!

The fairing was fitted and when viewed from a firewall looked like a caricature of the Cat in the Hat. Examination of the stab skins showed that they did not line up so this had to be corrected. This should have been picked up at assembly were the leading edge skin could have been corrected easily.

Refitted the faring and it now looked like the Cat's had a hard night at the local bar, re-examination showed the base was now not square to the fairing vertical, to fix this the base was sanded to square.

At this point the next issue became apparent - the ABS former was square to the old base and with the fairing square now square to the new base but it now looked like the Cat had put the hat back on after a full week binge.

Misalignment of leading edge

At this point the builder responded by applying a series of incantations based on dubious parenthood and upbringing and after a cooling off more bog was added in anticipation of a round of fresh sanding at the next work secession. This capped three of the most unproductive weeks I have had on the project - ugh!!

Rudder Stab - Part 2

It was pointed out to me by Franco from Flying Legend that the first third of the rudder and elevator stabs are to be flush riveted. This had been missed at the assembly of the rudder stab and it was intended to leave it that way, however the inclusion of a beacon on the top of the fin lead to a rethink.

Rudder Stab
To provide a route for the beacon wiring the stab the leading edge was the most suitable route with the option to flush rivet only requiring de-riveting it would be possible to kill two birds with one stone.

Once removed the fin and ribs were dimpled using the same tool & technique used on the elevator stab. Dimpling was added to each hole up to the but not including the front spar. 

Two [2] 20 gauge wires were run up the face of the stab using a series of 1/2'' flared holes added using a hole saw and flaring tool as used on the side covers. The cable's were inserted in a nylon web cover located using nylon saddles and riveted to aluminium angles folded from 0.020'' aluminium.

The front nose was reinstalled, clecoed after a final check re fixed using countersunk rivets. 

Stab Assembly - Part 1

The stab kit consists of a series of pressings, skins and mounting brackets. All holes are matched drilled by the factory so the major task faced by the builder is the correct assembly of the parts. Begin by identifying the parts and their locations by studying the 3D illustrations in the factory assembly manual.

You will need about 150 clecos to fully assemble the frame ready for riveting. All rivets used are 1/8 pop rivets supplied by the factory as part of the kit.

As part of the assembly four [4] captive nuts supplied MUST be fitted to the inside of the rear spar. This was missed by this builder and later required a quick back track to under take the task.

The front attachment has to be now prepared to allow the frame to be installed into the fuselage. Fit a bolt through the single attachment point - the hole on this one was chased out using a tapered hand reamer fitted to the battery drill. Align and clamp then match drill one 1/8'' hole through then fix with a cleco as shown then drill all holes to complete the part.

At this point assemble the rudder hinges. The bracket with the slots are the top hinge. Note: The bracket with the bearings are fitted to the rear stab spar in both cases.

Assemble using a AN4 bolt and nylock nut with a aluminium full washer placed on both bearing to  space  the  brackets clear of the bearing faces. These have too be disassembled  to install the brackets into the rudder later.

Before fitting the rear spar to the fuselage install four [4] to the rear bulkhead and the deck. This builder chose to rivet the skins with the stab installed to the fuselage. The rear spar is fixed at six [6] point provided with AN3 bolts and nylock nuts.  Refer factory assembly manual for details. When complete fix at the front using a single bolt and nut.

The rear rib on this kit required a slight trim to allow fitting. Once correct fit clecos to the two [2] holes then match drill from the front - once done fit the final rib and cleco. Fix all 5 points with 1/8'' pop rivets. Review the factory notes for final details and only when 100% sure fit the skin to the open side in preparation for riveting. If there is any doubt ask your technical adviser to come over and check all the points.

There are two [2] lower infills strips to complete the rear rudder shroud - slip under skin and align as shown then match drill as shown. Both shrouds MUST be drilled before fixing to allow access - see image above. The drill shown is a long series aircraft drill with its primary feature being a short area of fluting compared to its commercial equivalent.

The backing strips located on the inside face of rear spar located at the base shown on the drawings and MUST be installed as in accordance with the factory drawings. The backing strips are pre-punched and will fit either side.

Note: The stab will have to be removed to allow installation of the horizontal stabilizer but this builder decided it would be a good place to start , access would be easier and with this approach the frame is jigged to the aircraft during assembly.