Building a Sports Model – Part 5

The root  ribs are cut from 1.5mm ply and glued to the foam wing cores.  Also included are a 5mm bolt for mounting to the fuselage and two locator lugs made from leftover carbon-fibre rods.

 

The wings are now ready for sheeting with 1.5mm balsa.  First the sheets need to be glued together along their edges.  They are taped together, flipped over and yellow glue applied along the joins, then weighted down while they dry.

 

Gluing the sheets to the foam wings can be tricky, as it’s very important to get a consistent bond.  But with the right tools it’s actually very easy.  

Yellow glue is spread with scrap balsa like butter to cover every bit of foam.  The balsa is laid in place hard up against the leading edge, and now for the tricky part.  The wing is inserted into a giant vacuum bag from Bunnings, and the air sucked out and left to dry overnight.  Clever eh?  Perfect results every time.

 

Do that with the other three sides, trim the edges, and the wings are now super strong and light.

Building a Sports Model – Part 4

The servo rack was installed into the fuselage with a couple of Savox servos.  The rudder wires can be seen attached for initial fit testing.

 

Below, the wing tube and other holes were drilled and the wing spar tube aligned and glued in place

 

Less than three months after replacing my phone camera lens I’ve broken it again, so all the photos are going to be a little hazy.

While waiting on the canopy to arrive, it was time to get the wings sorted out.

The foam cores needed a strip of fibreglass glued to the top and bottom trailing edges to give them strength, and balsa leading edges were glued on.

A hole had to be measured and cut under the wings for the aileron servos, as well as for the centre plywood rib which was glued in.

 

Now a rather tricky hole had to be made through the wing to the servo cutout for the servo cable to access the receiver in the fuselage.

For these the tip of a 12mm steel rod was heated with a blowtorch, placed into a rough jig and rammed through the wing, melting the foam as it went.  

It’s a lot easier than it sounds really.

Building a Sports Model – Part 3

I know how excited everybody is for the next instalment, but I must insist on patience as these things take time.  What with all the fan mail I receive from on-line casino owners and Russian women making marriage proposals – sorry but there’s only so much of me to go around.

The tail feathers were the next step, and they were a lot of work.  First they were framed up from 10mm balsa, then hinges and control horns set up, and mounting points for bracing wire added.  The wood was filled and sanded to shape.

 

The framework was covered with an acetate lining material called Bemsilk, glued and sealed with aircraft dope.  Very cheap and effective.

After adding a balsa mounting block to the fuselage, the horizontal stabiliser was carefully glued in place, making sure it is aligned in all 3 dimensions, and especially parallel with the wings.  The aluminium bar represents the sit of the wing.  

 

It might look off-balance in the pic, but it’s just a dodgy photo.

The vertical fin is then glued in place square with the horizontal stabiliser and in line with the fuselage centre-line.

 

That’s another major job completed.

Next was to install the control systems and servo rack for the tail.  The rudder will use a pull-pull system, and for the elevators I made up a double-pronged carbon-fibre pushrod.

To be continued…

Building a Sports Model – Part 2

Before a model starts to look pretty, a lot of work has to go into installations.

First to the business end of the model, and mounting the engine.  The plans call for an offset engine mount, about 2.5 degrees to the right, which helps to deal with engine torque that tends to roll the aircraft to the left and can cause catastrophic tip stalling on take-off.  A shim was made from hardwood to sit behind the engine mount, and the engine mount centreline is shifted 7mm to the left so that the prop hub remains in line with the centre of the fuselage.

From the picture you might be able to see how neatly the muffler tucks underneath the side-mounted motor – a  perfect arrangement.  The whole lot is hidden inside the cowl. This might seem trivial but experienced builders will know why it’s exciting.

A 6mm ply firewall was also glued inside the model as the one built into the fibreglass is way too thin.  The engine mount is held in place with 5mm screws that go into blind nuts epoxied into the firewall.    That’s probably the trickiest part of the build completed.

Behind the firewall you can see a 1.5mm ply tank mount that will be screwed onto ply brackets, which are epoxied to the fuselage.  The 20oz tank will be held down with two velcro strips (you can see the velcro slots).

(The ribs in front were cut from 1.5mm ply in preparation for the wing construction while waiting for glue to dry).

Above is a view from inside showing the tank placement and throttle servo.  Behind that is the servo tray installed for the rudder and elevators from 3mm ply.

The throttle servo is connected to the carburettor with 4-40 threaded rod, which is joined to a 6mm spruce rod for stiffness.

I immediately adjusted the servo throws to prevent any future damage.  The servo end points were initially set to 50% each way, then graduated up from there to achieve a fully open and fully closed throttle.  This is all very easy with modern computerised radio transmitters.

Building a Sports Model – Part 1

With our myriad fans clamouring for more website posts, it’s time to show the masses what goes into building a flying model aircraft.

After asking around the club for a ready-to-fly, easy-going, 60 size sports model, I was handed the exact opposite: a fibreglass short kit for a 30cc IMAC stunt model. (IMAC is a competition class for more-or-less, mostly less, scale aerobatic aircraft).

But to be honest I wasn’t sorry – things like this don’t come your way every day, and a kit like this is pretty rare.

The model is a Laser 200 with a 2 metre wing span, and it comes from PBG Composites in New Zealand.  It must have been stuck in a time capsule because they seem to have stopped making them at least 10 years ago.

Above – the real thing

 

Below – short kit  – fibreglass fuselage and engine cowl, plans, undercarriage, neat carbon fibre wing joiner

 

Below – foam wing cores

The first question to ask of a nascent model is what sort of power plant it desires.  These days electric motors are popular but not with me.  A 30cc petrol motor would be the usual choice here, but a glow-plug motor is much lighter, smaller and simpler, so I picked up a second hand OS 1.20 to run a 16 x 8 prop.

And I’m glad I did because these are fantastically well sorted motors – amazingly compact with a power muffler that has a very neat attachment for changing its position.

Then there is all the other hardware and materials to purchase.  A dozen sheets of balsa for wing skins, a sheet of 1.5mm ply, 10mm balsa, fibreglass cloth, engine mount…

Below – the stuff required: fuel tank, servo arms, servos, wheels, tail-wheel, control horns, spinner, propellers, wing leading edges, control hinges, battery, s-bus terminal, receiver…

…and now we’re ready to build.

‘Up in the Air’ Festival

The club is participating in Lake Macquarie’s ‘Up in the Air’ Festival to be held at Rathmines Park on Sunday 23rd May.

EDIT 26th May:  Photos of the club stand erected for the event

 

“This is a fantastic opportunity not only to see … spectacular aircraft soar over Lake Mac, but to enjoy a host of land-based entertainment in a beautiful part of our City,” someone said.

More to the point, it’s an opportunity for the club to get some public exposure (no, not the Jacko kind of exposure).

A marquee is being organised to display an assortment of models and what-not, to provide information to the public about this great hobby of ours, and maybe get a few people motivated to join us.

If you would like to help out on the day or provide some gear for display, please contact a committee member.

Tickets are $8 each, with free entry for children aged 15 and under.

Cessnock Airshow

Peter Jackson (Jacko) is interested in attending the Airshow at Cessnock Airport alleged to take place the weekend of 13/14 March. 

Jacko has a camper trailer with an annex of 2.4 metres, with an additional 4 metre extension if required. He is looking at free camping on McFarlane Reserve (flat, with some trees, plenty of space) in Broke from Friday night. There are toilets and an excellent store and Pub, a short walk away, with meals available.  You can swim in the nearby brook too. Dog friendly. 

He would love to organise a group to “Do” a day or two at Cessnock Airshow with many lovely warbirds.  His extended annex would be available to any poor soul that needed a roof for a night or two, no charge there, but they would need their own bedding and a tolerance to good rum, or something else! 

Let’s do this and have some more Club Fun.

Contact Jacko for more details.

(Editor’s Note: Jacko promises to wear clothes… most of the time).

New Committee Elected

A new committee was elected at the recent AGM. Please click here for details.

Many thanks to retiring president Andrew for his efforts over the past couple of years. The field has been developed and club membership increased substantially during his presidency.

Thanks also to Brian, who has volunteered an enormous amount of time and effort in fulfilling the dual roles of Secretary/Treasurer for many years, rendering invaluable service to the club.

AGM Saturday 10th October 2020

The club AGM is to be held this Saturday 10th October.

1.00pm start time at the flying field, aiming at a short meeting.  All members are encouraged to attend.

New committee members are to be voted in.  Nominations are open, particularly for the positions of President, Treasurer and Secretary, with Brian and Andrew not wishing to be re-nominated.

If you are willing to take on one of these vital roles please let Brian or Andrew know.