Rotary Home Built Aircraft
4A -14Pt.docx
A HOMEBUILT LIGHT AIRCRAFT
PRESENTED TO ROTARY - NORTHBRIDGE JUNE 2017
Someone said to me that Rotary should have asked someone who has completed
an aircraft!
That’s not me. I’m still building.
I also saw one listing for this evening as, “How to build an aeroplane”! This is a
look at a small part of building one type of aircraft. This talk will be type specific.
As Rotary is not going to the aircraft I have brought a piece of the aircraft to
Rotary for “show and tell”..A forward fuselage side panel. Look but do not touch.
No greasy thumbprints please.
So what exactly am I building?
#1 Image of Sonex
This the first question I am often asked.
I tell them a Sonex light aircraft. Except for some aviation people no one has
heard of it.
Most people say “Oh an ultralight” thinking of a long aluminium pole with a lawn
mower engine on one end and a single surface floppy wing.
#2 Image of Ultralight
This is a basic Ultralight.
My aircraft is not like that! It will look like this.
#3 Sonex Image (Cdn)
This one is a Sonex Canadian built. I like the polish and colour.
Tonight I will talk about the Sonex light aircraft I am building and try an explain
what drives some one to spend 2000 hours of blood, sweat, tears to build an
aircraft.
Here are some details of the Sonex.
The Sonex is a mostly all metal aircraft with a single engine.
#4 Image pointing out F/G?
There are odd bits of fibre glass and plastic here and there, principally in the
canopy, engine cowl, wheel spats and wing tips.
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Nominally a kit, but the Sonex calls for a lot of parts to be made by the builder.
#5 Raw materials
Around 70% of the “kit” is raw materials. In this image there are long pieces of
channels. The box is full of 1” x 1” x 1/8” angle. All have to be reworked into
parts. You can see some of the angle on the fuselage side I have brought in.
The aircraft type is of US origin. This means Imperial measurements which
have been mathematically converted to metric. You end up with easy dimensions
to manage like 81.2mm. Have a look at the plan sheet I brought in.
#6 Main Sonex Image Again
Here are a few Technical Specs of the Sonex aircraft
Warning here - Tech Jargon Alert.
The Sonex is mostly aluminium 6061 T6 grade. A grade not available in the
aerospace section at Bunnings It is a lot harder than domestic aluminium.
The aircraft accommodates a pilot and one passenger seated side by side.
Wing Span 22Ft - 6.7 Metres.
Length 18 Ft - 5.5 Metres
The power in my aircraft will be provided by a 120 HP/90 KW air cooled 6
Cylinder Jabiru aircraft engine. Made in Bundaberg. Qld.
Maximum Take Off weight is 1200 Lbs/545 Kgs.
The Sonex is aerobatic at reduced weight.
For the pilots here, some G Load numbers.
Utility Category +4/-2 G
+6/-3 G at aerobatic weight.
Ultimate Load Limit’+9/-4.5 Limit.
Cruise Speed at Sea Level 130 MPH/210 Km/Hr 120 Knots
Cruise at 8000 feet is 170 MPH/272 Km Hr
150 Knots.
Absolute max speed called VNE means Speed Never Exceed before something
breaks is 197 MPH/365 Km/Hr 170 Knots. =VNE
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Basically, a pretty quick and strong small aircraft.
The second most often asked question?
Why bother?
Image #6 remains
There are number of reasons, including the following, not necessarily in order of
importance.
Once completed I will know every component, bolt and rivet in the structure which
is brand new.
This is something I have been researching and thinking about for 20 years.
I should have started building then, 20 years ago.
My advice - if you want build an aircraft, start tomorrow!
The whole process is enormously intellectually challenging. I have spent as much
time poring over the 104 yes 104 A2 sized plan sheets as I have spent actually
building.
BTW there is no construction manual as such for the Sonex. Only small sheets of
notes for some procedures or a list of assembly work in part order on SOME not
all plan sheets.
Its fun… mostly! There is enormous satisfaction in seeing assemblies completed
and fitted.
Finally, as a brand new aircraft, It will cost about the same as a clapped out 30
year old Cessna or Piper aircraft.
#7 Image of Old Cessna 172
Like this one!
So exactly what is in the kit?
#8 Delivery Image 1
What arrives is a large box and a long cardboard tube. Carried in a container by
sea from the US.
When the shipment arrived the truck dropped the box in my drive way and two of
us had to roll it into the carport. It weighed 1000 lbs/455 Kg.!
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#9 Delivery Image 2
The large box contains everything but the wing spar caps (in the cardboard tube)
Also the engine and instruments are not supplied with the basic package from
Sonex.
#10 Image of inside of the box.
Inside the large box are lots of smaller boxes and a lot of channels, sheet metal
and angles for making the required parts.
There was damage to both the cardboard tube with the spar caps, and the pallet
base of the large case which contained a number of sheets of aluminium and a
few precut parts.
#11 Pre cut parts.
After giving the carrier and the freight forwarder a hard time about the damage,
(marine transit losses were my business previously) I later found that there was
no major damage.
Next came the Inventory
I systematically unloaded the case and the smaller cartons and tubes inside. I
then had to inventory every piece, including all the raw materials, and ensure that
it was listed and properly identified with the plans part number.
#12 Inventory image.
Parts were then stashed around my workshop, carport and inside the house. All
locations were recorded in the inventory. This took a few weeks.
Here is a page from the inventory spreadsheet.
#13 Inventory spreadsheet page.
“Green” Entries are parts that have to be made. “Purple” Entries have been
supplied but may require extra work. You can see the complexity of the job and
there are 11 pages of entries. This system has worked remarkably well with only
minor hiccups.
We now come to the actual building process.
#14 Master Sonex
Once I had completed the inventory and experimented with a few rivets I was
ready to start.
The aircraft is mostly held together with around 13,000 aviation pulled rivets
similar to “pop” rivets but, all stainless steel and much stronger and harder than
home use conventional rivets.
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After pulling a few of these with a hand riveter, I felt an urgent desire to own a
pneumatic (air driven) rivet gun. The power unit is much easier to use. The first
one I bought failed after a lot of use. Probably at around 9,000 rivets. I am now
on my second riveter.
The 13,000 rivets means that 13,000 holes have to be drilled through at least two
layers of metal. Often more and of varying thickness. Most holes are drilled twice.
Pilot hole size US Drill size #40 (2.5 mm) and final size US Drill Size #30 (3.25
mm) for the rivets. Also a few bolt holes up to 3/16” 4.75 mm
#15 Image of Clecos
In the images you will see silver and copper “clecos” sticking out of the structure.
These are temporary fasteners used to hold an assembly together until it is ready
for riveting.
As an assembly is drilled it is held together with clecos. But it then has to be
pulled apart and the holes “Deburred” to remove all the metal thrown up around
the hole by the drill.
#16 Image of Deburring.
This has to be done for every hole, and both sides of each layer to be rivetted.
The deburring tool is a simple hand tool like a countersink with a cranked handle.
It is tedious but effective. A power tool tends to be too aggressive.
Needless to say after around 9,000 holes I am now an expert at deburring.
#17 Image of Flap under construction.
First thing I built was a “Flap” Basically a triangular section box with a hinge
along the bottom edge. I eventually made both the left and right flap. I agonised
over these a bit. In retrospect I did not realise how easy they really were! There
was much harder stuff to come.
#18 Picture of Tail Skin
I then started the horizontal stabiliser on the tail. My first attempt was not
accurate enough, the skin did not fit, and it was pulled apart and the pieces of
channel cut down to the next smallest size required. The stabiliser was then
rebuilt with some new channel.
A wonderful learning experience!!!
The skin supplied by the factory was difficult to fit. Like a sheet of spring steel.
Not fully bent. However, I finally got it all together OK.. This is the Horizontal Tail
Skin before being coaxed into shape!
#19 Images of Tail pieces.
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I then built the vertical fin and rudder. Tricky with hinges, heavy spar and a fibre
glass tip. Also hard to skin.
Next I started on the wings.
The Wings
.#20 Wing Image I have a reasonably sized workshop in my back yard. The tail
structures and the wings were constructed there.
Each wing has a “spar” running down the middle and it is a heavy strong
structure.
#21 Spar on bench.
This has to be assembled and rivetted with 450 “set” rivets. The kind you set with
a hammer type rivet gun.
A lot of work, and I was assisted by a friend from the US with both spars.
#22 Rivetting Spar.
Eventually the spars were completed and carefully aligned before precise drilling
and pinning in their installed alignment. Took 2 hours to set up for 5 minutes
drilling.
#23 Spars Pinned
Every Sonex builder has a picture like this with both spars pinned together
showing the wing span of the aircraft.
They were then pulled apart! They go into the wings after all.
#24 Wing Image on bench.
Assembly of the wings continued. They are of conventional construction. Ribs
and external skins.
The leading Edge skins (the curved panels on the front/leading edge.) are
supplied from the factory “partially” bent to shape. When taken out of the box
they spring open. Here we were using ratchet straps to try and pull the skins into
position.---Initially, it was not successful. We could not get enough tension to pull
the skin into position. (Without possibly damaging the wing in the process.)
#25 Bending Image
A colleague and I spent nearly a day learning how to bend the first skin close to
the angle required. We finally used 40 mm plastic pipe (to maintain the curve) and
Stephen’s body weight.
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The second skin was bent quite quickly. We knew how to do it!
#26 Wing Stand and Wrapped Wings Images.
Once both wings were completed they were put on a specially constructed stand.
Wrapped in plastic and taken by trailer to a friend’s garage for storage.
Then I started on the Fuselage
I decided that if I constructed the fuselage in my workshop in the back yard it
would be difficult (read impossible) to carry to the front for transport.
This would be particularly so if the engine was mounted and the under carriage
was fitted to the fuselage. It would be simply too wide and too heavy.
#27 Images of the front enclosure.
So, I enclosed one side of my carport in the front of the house to work on the
fuselage.
You can just see the fuselage draped in cloths etc. through the door.
The plastic enclosure remains wonderfully clean inside. Compared with the
usual inundation of the carport with leaves, nuts, flowers etc from the council
trees outside.
#28 Image of Fuselage
As of today the fuselage is well underway and I should be setting it up on the
“gear” soon.
#29 Image of Fuselage.
The engine ordered some months ago is yet to arrive.
Polishing! Why Polish?
In the images you will have seen that most of the components are highly polished.
It is much easier to polish the components BEFORE assembly. They will be
buffed up after assembly as required.
I am often asked why do you polish those panels. Most aircraft are painted. Like
this one also a Sonex type.
#30 Painted Sonex image.
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Even a small aircraft like this may have 15 lbs/7 Kgs of paint or more on it. With
minimal paint, that’s 12-15 Lbs of extra fuel/baggage tools that I can carry.
Having said that, polishing is a lot of extra work.
#31 Images of polishing tail skin.
Technical Inspection
I am asked constantly whether CASA Civil Aviation Safety Authority
the aircraft as it is built.
inspects
The short answer is that CASA has pretty well removed itself from building
supervision of homebuilt aircraft as construction is under way.
I am required to be able to demonstrate that I have completed at least 51% of the
aircraft and to that end I keep a detailed log of the work carried out together with
photographs, some of which you have seen here.
#32 Build Log Image
Here is a page from the build log.
Various sports aviation groups conduct their own inspections as building
progresses. In my case I belong to the Sport Aircraft Association of Australia and
they have “Technical Counsellors” who inspect and approve the construction if
satisfied. They will also offer suggestions for any modifications thought
necessary.
#33 Main Image
CASA do authorise “Approved Persons” who for a fee will come and look at the
aircraft and its paperwork prior to a first flight. If the AP is happy with the aircraft
and the paperwork, he will issue a limited certificate of airworthiness. He then
reports to CASA.
The limited certificate of airworthiness allows the owner/builder to fly off 25 hours
near the nominated home airfield. If nothing breaks and the aircraft performs
satisfactorily, a full certificate of airworthiness is usually issued.
Completion
I am hoping to have the main construction completed by the end of the year.
Final assembly will be at a suitable accessible airfield as near to Northbridge as
possible.
Warnervale and Rutherford (Maitland) airfield are contenders at this stage.
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Once the aircraft is at the airfield there will still be a lot to do. There is a saying in
the aircraft home building biz, that the aircraft is 95% done and there is still 95%
to do.
Hopefully, first flight will be around the end of January. But, things always take
longer than anticipated.
Finally, I have to point out that I could not have got as far as I have with this
project without the support of my wife Pam. She has been behind me all the way
and an extra pair of hands when needed. Thanks.
I hope I haven’t bored some of you rigid! But, that’s most of the story of my
Sonex so far.
Thank You!
Questions?
Rotary Home Built Aircraft 4A -14Pt.docx