Panel Mount - Part 4

This blog cover the manufacture and installation for a electrical component mount

Overview
There a a number of components to connect the various electrical devices and some where is required to mount it. After reviewing photos of the factor aircraft it was decided to create a mount running along the top of the wheel well. This will allow good access from either of the access panels in the top of the cowl and to the rudder pedals below.

Manufacture
The original aluminium tunnel was replaced earlier with a S/S copy, it was trimmed to a C channel with 65 mm deep sides and a 10 mm lip. 

Next a mount was fabricated from 0.020'' 2024-T3 aluminium angles and riveted together to create a Z profile.

Finally the channel was primed on both sides and painted satin black on the top side only for appearance.

Installation
The front side was notched added and a doubler fitted to stiffen the connection. With the channel trimmed to length the lower panel and the Z were matched drilled. Once the fuel selector is fitted it will be fixed with M3 rivet nuts at both ends to allow removal if ever required.

Stiffners will be required and will be added one the equiptment is laided out in the future.

Panel Upper - Part 2

This blog covers manufacture of the main panel

Panel Layout

The panel layout is heavily influenced by the prototype aircraft and created a mix of 1 1/4'' - 2 1/4 - 3 1/8 inch steam gauges plus a central GPS / EFIS to help create that military feel.

Some gauges are more that would be generally required like water temperature and EGT but as this aircraft is fitted with a number of experimental items and products that have not been used in this market this builder would like to verify the claims made for these items.

The panel logic will be examined in detail later in the build.

Marking Out
The panel layout drawing was drawn and plotted full size, then fixed to the blank panel using masking tape. Using a small hand punch all instrument centers were punched including the corners of the vertical and horizontal cuts, finally the hole's were marked using a 2 mm drill.

Template fitted

Drilling reference holes

Note: The centers were enlarged with a automatic center punch before drilling using a flat table. This allowed the initial center to be located by feel and re-punched. The same process was used for the initial drilling, with the drill located on the center mark by feel and then drilled. Later this was enlarged to 4.5 mm before drilling with the hole saw.

Once complete all holes were dressed and de-burred.

Drilling instrument holes
All initial holes enlarged to 4.5 mm to allow
hole saw drill to center

The panel was trial fitted to the cowl and the corner radius were found to be too sharp and had to be corrected. 

A copy of the panel was cut using 4 mm foam core sheet and a guesstimate radius developed after examining the gap on the trial install. 

The foam core was the cut and sanded with a trial fitting confirming the radius as correct. Using the foam core as a template the new radius was was transferred to the existing panel and the new radius created using a 300 mm disc sander.

Correcting corner radius

The lower mounting angle was installed after drilling to suit the isolation rubber. The angle was then drilled with a series of 9 mm holes pitched at 30 mm centers using the factory drilling jig. The angle was the match drilled using the panel and M4 rivet-nuts then fitted to the angle for panel mounting.

Mounting angle

The final task was to determine the location of the upper angle panel support. A scrap piece  of angle was clamped to the panel with all the items fixed using their respective mounts and a packer placed under the end of the angle to bring the face of the panel into alignment.

Setting alignment

With the panel aligned the front was position to the underside of the cowl, next a offset line was created to allow for the panel thickness and a 30 x 20 x 0.020'' 2024-T3 angle fabricated, drilled for 4 [four] large head 1/8'' rivets in two staggered rows to ensure the angle is flat.

Top mounting angle

The parts were reassembled and the angle match marked from the panel then removed drilled and 2 [two] M4 rivet nuts fitted.

Comment: Doing it again I would correct the radius before any marking out as this effected the instrument layout and required a new panel to be created.

Panel Cover - Part 3

With blog will cover modifications to the instrument cowl. 

Modification
One item that I did not warm to was the ears on the panel cowl for the air vents, so it was decided to modify the cowl to match the current Tucano LSA..

The existing comb had two 3.2 mm hole drilled in each mounting flange with mating holes into a scrap piece of 12 mm ply to keep the panel in shape after removing the ears.

A motor tool was use to remove both ears and a drum sander chamfered the edges to ensure a good bond to the new fiberglass.

The gap's were filled from the underside using some scrap 0.016'' aluminium sheet with the plastic still on the faces secured by celco's to form the profile.

Ready to fiberglass mounted in the ply jig

Lengths of 100 mm x 4 oz cloth tape were cut to provide three [3] layers. West Systems 105 Epoxy and slow cure resin were mixed and applied with a small brush, finally peel cloth was applied to the final layer and excess resin removed. 

After drying the peel cloth was removed along with the scrap fiberglass. 

The top side was sanded with a rotary sander with 120 grit paper to blend the new fiberglass.

Fiberglass and peel cloth curing

A batch of macro was mixed using resin with micro balloons and applied to the new area. When dry the profile was sanded using 120 grit paper in a electric sander blending in the new areas with the original cowl cover. 

This was repeated to obtain the final profile.

Finally the upper side was primed and sanded with 320 grit paper then spot filled using blade putty, sanded re-primed and sanded for painting.

Fitting modified cowl

The cowl was installed onto the mounting angles installed previously, after match drilling 4 [four] holes and trial fitting M4 rivet nuts were installed and cowl secured.

Comment
The new LAS Tucano Sports has a cowl that is the same as this visually.

Canopy Bubble - Part 3

Installation

A 10 mm bead of adhesive was run around the perimeter of the frame over the stand-off beads to the size recommended and the a second at the base of the frame

With two people the canopy was lifted over the frame, stretched and fitted to the frame and a problem was noted.

The edge would not extrude the sealant without finger pressure and this required the use of clamps of which there were not nearly enough. A run to the local hardware store was required and about $195 worth of clamps purchased. These were applied with small blocks and light pressure applied to align the canopy and extrude the excess.

At this time is was beginning to go off so a mild sweat was raised. The excess mostly extruded at the base creating a awful mess but as I was time challenged. Cleaning up, Googled cleaning up Sikaflex 295 and read a comment like "cannot be removed after curing"

The aftermath - leaving for a holiday

Time to hit the panic button. Having no white spirit I resorted to the only safe choise I had available. WD-40. This raised more than a light sweat but 95% was removed. 

After curing I found that it can be rubbed off unprepared perspex with the thumb as outlined by Dave in his UK notes. 

This is a difference called experience.

What went wrong?

Blogger

Home-builders are faced with a real problem - that is they have to be a master of the process with no experience - sorry to all those human resource's managers who believe you only need training, nothing is a substitute for experiance. 

Application of these products is a skill to complete correctly so all there is to do is review the outcome and learn.

Comments

Sika was chosen as I could not find the product that Dave used. It's a complete system, has documented performance and was available locally.

I liked the idea of the additional stiffness these products provide - 30% of the torsion rigity of a modern car body is in the glass attachment.

White was chosen as the Shorts Tucano has a distinct white border and the thinking was when I edged it would look correct if it ended up to large.

The cons are application of the primer -  it is black and cannot be removed except mechanically  - I have a spot to remove but it will be handled by a professional.

The selection of the chamfer and the outside edge as the cut line - this created a tight seal and if doing again the inside edge would be used with a square edge. This was discussed previously but the builder lacked the courage to cut the perimeter again. The conclusion is that there is more than enough adhesive area. 

Should have used tape alignment mark at both ends as one side is too high by about a 1 mn and exacerbated the problem - forgot.

I would make sure I have at least 15 - 20 quick clamps or small sash clamps with plastic covers. Also have a series of 3 x 1 DAR pine cut onto 150 - 200 mm lengths covered with packing tape for quick release.

There would be a bottle of white spirit ready for a quick clean up. Do not believe the technical representative who say "it cleans up easily with a clean cloth" - refer comments above

Do not use white sealant - black is the only choice

The inside face of the canopy not needing priming should have be tapped up and sealed - I missed this though I thought of it previously.

Time is your enemy with this product you have about 60 minutes to cleanup without owning a panic button. 

Would I do it again - leaning to a yes but will have to see how it cleans up. I may be saved  by the Shorts shroud and the white border - I hope.

Hope

Finito 2015

Final photo for the year - I like this one

Back in late January

 

Canopy Bubble - Part 2

Covers preparation for fixing the canopy

Materials
The decision to glue the canopy was based on the article from the UK dealer and the desire to achieve a slightly stiffer assembly. The most suitable material available locally is Sikaflex, after a lot of reading and speaking to their technical department the materials were selected. 

Sikaflex 925 UV White - 2 tubes [only one used]

Sikaflex Primer Aktivator 205 - 250 ml fibreglass frame - 1 off total

Sikaflex Promoter 206 G+P - 250 ml fibreglass frame - 1 off 
Sikaflex Primer Aktivator 205 -250 ml Perspex Canopy

Sikaflex Promoter 209 D - 250 ml Perspex Canopy - 1 off 

Brushes small - 4 off

Water proof paper towels - 2 rolls

Fabric wipes - 1 roll

Note: The sealant was the cheapest item in the list but the system will not meet manufacturers specification if these items are not used as outlined.
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This system is not be suitable unless a shroud is being installed or a black border is acceptable as the primer produces a distinct black border on the assembled frame.

Sika Data

Fiberglass - Sika instructions - Organic Window

Reference: Bonding the RV8 Canopy - click here

Preparation
The recess area was sanded with 120 grit aluminium open cut paper.

Marking points for the button points at a 60 mm pitch around the perimeter of the frame.

Next the stand-off's for the canopy, this was done using a standard nozzle placed on the frame and a 5 mm button produced then the tube was raised up and the second ring created with a light squeeze on the gun.

Note: These require 24 hours plus to fully cure 

All the buttons were trimmed back using a sharp box cutter allowing for the 2 mm thickness of the canopy.

The frame interior was sanded using 240 grit wet and dry, primed and sanded again with 320 grit aluminium open cut paper. At this point all imperfections were filled with spot putty and sanded to profile and the frame re-primed.

Two coats of satin black were applied but suffered blush due to the weather. Next day the area was sanded lightly and repainted with two more coats of satin black in the middle of the day.

Buttons applied

The canopy was placed inverted on two stands with a sheet of foam, rolls of bubble wrap from the canopy provide the necessary stability. Masking tape was placed around the interior perimeter 25 mm from the edge and scuffed using a fine sponge sanding block cut into cubes.

Edges prepared

Comment:

Need's two people and do not use white - there is a specific reason to be covered later

I would rather work on a IED!

Emergency Pump - Part 1

This blog covers the fabrication and installation of the emergency pump

Pump
The factory supply's a hand pump with the kit that is installed under the floor panel but there was an all aluminium pump in the cupboard. This is similar in design to one used in a Cessna Hydraulic Emergency Hand Pump. They are light and have an integrated handle but are expensive. This pump was produced for the White Lighting from memory but the Cessna pump would be lighter as it is all circular.

Installation

Bracket

A mounting bracket was fabricated from 2'' x 2'' x 1/8'' 2024-T3 aluminium angle and was selected as it would offer the necessary stiffness without a lot of additional reinforcing. It was lightened by drilling a lot of holes and at the was was about 100 grams [est].

The mounting points were marked off the pump with a 1/4'' transfer punch and then the profile shaped and lightened. 

Provision was made for mounting with 4 mm pop rivets to ensure a strong attachment to the top side of the wheel well. 

You do not want a pump moving about when in use as there would be enough pilot stress at having to use it.

Pump mounted to bracket
May shorten handle at a later time
Plumbing is still open 

Both mounting bolts are a AN4 with shear nuts to save a little weight.

Comments
The lower hole should have been tapped 1/4 x 28 tpi as it required a lot of grinding to remove the fillet to install a nut and the vertical lighting hole would be a little smaller but functionally it works well.

Panel Lower - Part 1

This blog covers the fabrication and installation of the lower panel

Mounting

Trial fit

With clecos securing the panel to the bulkhead #2 with the factory punched holes, the panel attachment's for the face of tunnel were marked with a felt tip pen, then all holes then drilled #30 for pop rivets.

Note: Factory calls out M4 screws and rivet nuts but pop rivets were selected for the installation as it creates a bulkhead tie and suited my equipment arrangement. 

Marking Out
The panel layout drawing was drawn, plotted full size and then fixed to the blank panel using masking tape. 

Panel design created with Draft Site
This has undergone many revisions from the original proposal

Using a centre punch all holes were marked including the corners of the vertical and horizontal cuts, finally the hole's were dimpled with a 1/8'' drill.

Drawn with Draft Site 2D

Marking hole centres
All marks dimpled with a 1/8'' drill, checked
and then drilled through

All corners to be drilled 1/4''
Face primed with Wattyl black etch

After pin drilling waste was cut-out with Dremel motor tool

Next the panel was pin drilled for the rectangular openings using the center marks as the corner's centers, then the remaining holes were drilled to suit the UMA fuel gauges.

The hole centers for the 1 1/4 gauges is critical and I had to slightly slot a few using a 1/8'' round needle file.

Painting

The panel was rubbed back with a Scotch-Brite then aluminium open-cut 400 grit and etched primed.  Once dry a single coat of satin acrylic was applied and allowed to dry. It was rubbed back with 400 grit paper then another coat was applied. 

When dry it was rubbed back again with used 600 grit wet & gry, detergent and water then set aside to fully dry. 

Note: The panel was wiped with a tack cloth for last paint application.

Once dry the panel was installed using pre-painted pop rivets into the pre-drilled holes.

Isolation Mounts
The existing holes were drilled and fitted with M6 riv-nuts previously, rubber isolation mounts were fitted into the riv-nuts with Loctite 222.

Panel installed with air vents - fuel gauges and fuel selector
Pilots air vents will be covered in later blog
Need's a vacuum to clean the swaf

Comments
Would leave the installation of rubber isolators until final installation as the Loctite makes them impossible to remove.

Move the fuel gauges in by about 5 mm to obtain a better balance in the appearance. The vents would be move across a bit to open up the area in the horizontal panel. 

Fuel selector is easy to use in this location and its full installation will be covered in a separate blog but generally it appear's to meet the design criteria set at the start.

Air vents are a bus / RV item from Ebay - 3.15" x 2.13" (80 mm x 54 mm) Rectangular Adjustable Vent with 2.00" (50 mm) Adapter. The adapter is important to connect the CAT hose to the inlets.