April 29

Week Seven – RC Plane Servo Setup

Full Hawklett LiveryHaving completed the covering I have to say, I am very pleased with the final appearance. I decided to pick out the main join lines between the Red and White with a black trim line and I think this works well. Here is a photo of the finished colour scheme standing proudly on its extended retracts.

The next job is to install the rest of the radio control gear, motor drive components and then carry out a complete rc plane servo setup.  I intend to drive the motor via a 60 amp ESC with separate UBEC circuit and a four cell Lipo of around 3700 to 4000 maH.

 

Installing The Radio Control Receiver

I use Spektrum DX6i radio control gear and I have Receiver & Satelite Identifiedexperimented using ‘Orange’ 6 channel receivers both with and without satellites. I have found these to be totally reliable and at a considerable cost saving over the original Spektrum receivers.

I am installing one such receiver with satellite in this model. This entails locating the main receiver in a convenient place to accommodate the bunch of servo cables and for ease of access for connecting and disconnecting the servos.

The latest six channel Orange receiver available here does not require a satellite.

There also has to be clearance for the short aerial that protrudes from the back of the receiver. This needs to be as far away from other signal carrying wires as possible.

The satellite receiver also has to be secured on a surface where the aerial is positioned at right angles to the main receiver aerial. Again this needs to be as far away from signal carrying wires as possible.

In order to protect the satellite receiver I wrap it in electrical insulation tape, without obscuring the LED that glows red when fully bound to the transmitter, so that it can then be secured to the chosen location using a spot of CA glue.

Aileron Control Surfaces to Servo Linkages

Being a frugal sort of guy I try to make my own components Hand Made Aileron Hornswherever possible. I know that moulded nylon control horns are relatively cheap but most involve a mounting plate and matching retaining plate that I find rather bulky and an unnecessary embellishment on the aileron surface.

The photo on the right shows the ones I have made for this model. These are cut from a scrap sheet of 1.5mm fibreglass PCB board.

These are let into slots cut into the aileron so that the pushrod connecting holes are directly in line with the hinge centres and secured using slow setting two part epoxy. Inset Aileron Control Horn

The two small holes in the lower stem ensure a good key for the adhesive. Once installed they look quite neat and there are no disruptions to the upper aileron surfaces. The sketch here on the right shows how they are installed into the Aileron.

Note how the linkage holes line up with the hinge point. This is very important.

Installing The ESC and UBEC

This model has a fairly narrow fuselage so fitting both theESC & UBEC Fixed Locations ESC and Lipo into the space available is quite a challenge. The swept back wing of this model necessitates the balance point being just in front of the point where the wing wheel legs exit the wing surface.

To get the balance point in the right place requires the Lipo battery to be as far back in the compartment as possible. There is just enough space in front of it to fit the ESC  and UBEC (Universal Battery Elimination Circuit) right up against the side wall.

I prefer to use ESCs with a remote UBEC. I find that they are more reliable as there is no heat transfer from the ESC to the UBEC circuit. This keeps things more stable with less likelihood of heat induced failure.

Lipo Location & Access

The photo here on the right shows how the Lipo fits in closeESC, UBEC & Lipo Located proximity to the ESC and UBEC and, as mentioned previously, needs to be in the most rearward position possible.

The Lipo is removed by sliding it forward and upward toward the front of the fuselage which in the photo is on the left. A ‘Velcro’ strap will retain it in position.

The forward base of this compartment (see photo above) is removable for access to the nose leg retract installation. Slots will be cut in this base to facilitate the installation of the retaining strap.

Receiver & Servo Wiring

There are six servos in this model for the following controls:Receiver & Servo Wiring

Ailerons – 2

Rudder – 1

Elevator – 1

Retracts – 2

Four of these are located in close proximity to the receiver so it is important for the leads to be organised and kept tidy. I use nylon ‘tie wraps’ to keep them neat.

The two aileron servos are connected through a ‘Y’ lead located within the wing. This then connects to a short extension lead that remains permanently connected to the aileron socket on the receiver. The ‘Y’ lead and the short extension are connected before fixing the wings to the fuselage.

A further ‘Y’ lead is required to connect together the fuselage mounted retract servo for the nose leg and the wing mounted retract servo for the two main legs. this then connects to the ‘Gear’ socket on the receiver. The connection from the receiver to the nose leg servo remain permanently attached whilst the link to the wing servo is disconnected each time the wings are removed.

Final Setup

So far, all testing for servo and control surface movement has been done using my trusty servo checker. The next  step is to bind the receiver to the transmitter and check all control throws and make any necessary adjustments. This will then complete the rc plane servo setup necessary before committing  her to flight.

Once this is done I will be testing the motor static thrust using different propellers. The total weight of the model with flight battery installed is approximately 5.5lbs (2.5kg). I am aiming for a maximum power to weight ratio of 11owatts for every one pound of model weight.

Using a four cell Lipo means that with an operating voltage of around 14 Volts, I will require a maximum current of 43 Amps. (Current = watts x weight/volts)

110 Watts x 5.5 lbs/14 Volts= 43.2 Amps

Based on this calculation I will be trying various propellers to find one that provides this power and current draw. The motor has a kV  (revs per volt) rating of 900 so with a 14 volt input the maximum rpm will be close to 12600. This is quite high so the appropriate propeller will be a fairly small diameter and medium pitch.

Watch this space for the final details next time. If you have missed my previous build blog posts, the first one is here.

I hope you don’t mind me reminding you to visit my main website www.rookiercflyer.com, especially if you are new to the hobby.

Colin

 

 

 

 

April 23

Step 6 – How I Cover Balsa Wood RC Planes

At the very end of last weeks post I featured a photo of the HawklettHawklett Colour Scheme in the bare wood state apart from the Anti-Glare panel and the motor access panel. In this post I propose to take you through the process of how I cover Balsa Wood RC Planes.

This is perhaps one of the most rewarding tasks as by the end the model has turned from a dull bare wood airframe to a glowing colourful thing of beauty (if done well!). The job requires the use of some basic tools that I will go through with you before I get started.

Essential Tools for Covering

The images here on the right show the basis of my adaptation of the  original RAF trainer version of the Hawk jet on which this model is based.

I am using a heat shrink polyester material to achieve this scheme. This type of covering is available from various companies. Most reliable model shops and suppliers will stock it.

Being a heat sensitive product an appropriate heat source isProlux Heat Shrink Iron required to adhere it to the surface of the balsa wood. There are two options one of which is necessary whilst the other is desirable but not essential.

The options are either a dedicated modellers electric heat iron with temperature control or a domestic electric clothes iron. The former is the best option as it can be used to access more confined spaces and is specifically designed for the job. Having said this, it can be done with the domestic iron but not so easily.

In addition I use modelling pins, a soft cloth pad, scissors and a scalpel with new blade. To aid accurate cutting I also use a 1M straight edge, a short ruler and a plastic transparent set square.

When using a blade and straight edge to achieve a true straight line cut in the polyester material it is necessary to have a good cutting base. I use a compressed fibre board with cork laminate attached to the top side. The cork takes cutting from the blade and is self sealing as the blade passes over it. A good alternative is a sheet of plate glass which does not blunt the cutting edge of the blade.

Cutting Heat Shrink Polyester Material

Covering films are supplied in widths that vary from 26ins (0.66M) to 1M. It can usually be purchased in multiples of 3ft or 1M lengths either in pre-packed sheets or cut from the  roll.

Having ordered and received delivery of the two colours I had decided to use, I planned out the best way to cut the necessary panels to cover all top, side and bottom surfaces of the fuselage and fin, the panels required for the tops and bottoms of the wings, stabilizer, ailerons and elevators.

This is quite an exercise in logistics but if done well can save a considerable amount of wastage. Having said this, it is necessary to allow a good margin around all panels to enable them to be gripped and stretched gently over the surfaces before pinning in place.

Preparing To Cover The Surfaces

My preferred method is to cover the largest areas first followedTesting Temperature Of Heat Shrink Iron by the smaller areas and individual parts. When using multiple colours it is advisable to apply the light colours first followed by the darker ones.

The first thing to do is to clean the surface using a ‘tack’ cloth. This ensures that there are no bits on the surface to show through the finished covering. After removing the film that protects the adhesive, I lay the material over the surface to be covered and gently stretch it into position. I hold it in place using modelling pins located at strategic positions.

Whilst doing this the shrinking iron has been heating up ready to start attaching the covering to the surface. I test the temperature by placing a very small piece of material, adhesive side up, on the shoe of the iron and if it starts to curl up and wrinkle the temperature is correct. Most Covering materials will attach to a balsa wood surface when the iron temperature is at around 150 to 170 degrees Celsius.

Attaching & Shrinking

With the covering pinned in place the first step is to run the shoe of the iron all the way around the edge so that it adheres to the wood. Once firmly held in place, I slightly increase the temperature of the shoe so that the material will start to shrink when it is moved steadily over the surface.

I try to keep the shoe just above the surface to avoid scratching the high gloss finish. Moving slowly the covering will shrink with the applied heat. Using the soft cloth pad I follow the shoe, gently rubbing the covering down on the surface to eliminate air bubbles and cause the adhesive to adhere to the wood. Any small wrinkles can be removed by re-heating the surface and gently rubbing the surface down with the soft cloth.

Once the complete area has been shrunk into place the excess material can be trimmed off and the edges smoothed down with the hot shoe. Corners need to be carefully trimmed so that the covering can be sealed across them. Curved edges, such as wing tips, need to have a surplus of covering left. This allows it to be pulled over the curvature whilst shrinking down with the shoe. Initially this technique takes aIroning Covering Joint Line 2 bit of practice to perfect.

Where two colours overlap, having first sealed the underlying covering, the first part of the top covering to be sealed is the actual join line. Here I touch the sole of the iron gently on to the overlap to tack the edge down. I take care not to apply to much heat so that the edge does not shrink way from the intended join line.

Having completed this tacking I seal all of the other edges before shrinking the covering down to the surface. I take care not to run the iron sole over the join line as the softened adhesive could cause the edge to shrink back from its intended position.

Nearly There

With just the ailerons and wing underside centre section to cover, she’s beginning to look much how I envisioned when I first chose the colour scheme.

Next week I hope to have finished these small tasks and installed the receiver, ESC, Lipo retaining straps and linked up all of the servos. I have to say that as an example of building balsa wood rc planes, this project has given me as much pleasure as I anticipated it would.

I do hope you are enjoying following this post and may be encouraged to have a go yourself at some stage. There is nothing more rewarding than the feeling of achievement and pride when the finished article takes to the air.

My website www.rookiercflyer.com is available for those needing help getting started in our wonderful hobby. Please feel free to share this post and the previous five posts with anyone you think would appreciate them.

Talk next week,

Colin

 

 

 

 

 

 

April 17

Stage Five – How I Scratch Build RC Planes

Last time I said that I hoped to be able to show youFully Glazed Cockpit the Hawklett partly covered. Well, later in this post I will have  a photo showing just that.

Build progress doesn’t always go exactly to plan due to unavoidable delays and every day life interferences. This last week has been one of those weeks so unfortunately progress has not been as good as I’d wished.

Never-the-less, this demonstration of how I scratch build rc planes has made some progress so let me talk you through it.

Finishing The Cockpit

As you can see from the first photo, having received theCockpit Catch new bottle of ‘canopy glue’ I have been able to finish off the glazing.

It’s quite amazing what you can do with a nice clean soft drink bottle, a plug made from scrap balsa wood, a hot air gun, bits of scrap balsa for the interior furnishing and Humbrol matt paint! Eventually I will be outlining the canopy frame using lining tape.

Initially I had intended to rely on the strength of the magnets to hold down the rear of the canopy/battery compartment cover. On reflection I decided that it would be prudent to latch down the rear of this component to avoid loosing it in high ‘G’ manoeuvers. Consequently, I have fitted a spring loaded catch at the top of the fuselage immediately behind the cockpit. This latch engages with a tube let into the rear former of the cockpit assembly.

Covering The Wings

The picture on the right shows the top of the wings fully coveredWing Topside Covered in 1.5mm (1/16″) balsa sheet.  Two sheets of 100mm wide balsa were joined edge to edge. My method of doing this is to apply a run of masking tape along one edge of the first sheet. I then place the second sheet hard up against the first one pressing down on the masking tape.

I then fold the masking tape in half with the two sheets back to back and run a bead of white glue along both mating edges. When they are laid flat on the bench the excess glue is squeezed out of the join line and wiped away using a damp cloth. I then pull the edges together tightly using pieces of masking tape across the joint. This is left to dry weighted down with various heavy flat objects.

Once dry the sheet was placed over one half of the the wing surface and lightly pinned in place whilst the outline was marked for cutting to size. Once cut it was attached to the curved surface of the wing using white PVA glue applied to the complete frame and rib edges. Whilst drying it was held in place using copious pins and masking tape.

The underside outer sections were done in the same way. Full length sheetsRetract & Servo Plate were not practical due to the need to cut out the wheel wells, leg recesses and undercarriage mounting plates, to say nothing of the aileron servo mounting/access plates.

These areas were covered using cut pieces of 1.5mm (1/16″) balsa sheet joining edge to edge and glued with thin CA adhesive. You can see from this photo that this area is fairly busy and needs care to get the covering correct.

Having completed the covering, small cracks and gaps were filled with lightweight filler which was sanded smooth when dry.

Checking Incidence of Wings

As this model is an aerobatic type with fully symmetrical wing cross section, the wing is set a ‘0’ degrees of incidence. This means that the centre line through the leading edge to the centre of the trailing edge is parallel to the model’s datum line.Datum Line

I know, you’re going to ask me ‘what is the datum line?’ Well here’s an official dictionary definition: “The horizontal or base line from which the heights of items are reckoned or measured as in the plan of an aircraft, etc.”  

Often this reference line will be drawn through the centre of the thrust line unless the engine or motor has down thrust built in. In this case a Spirit Level on Stabilizerdatum line is usually drawn below or above the main drawing and everything is measured and positioned above or below this line.

OK, enough of this technical stuff, let’s get back to the incidence check. The stabilizer of this model is set parallel to the centre line so in order to check the wing incidence I had to set the fuselage inverted on blocks so that a spirit level laid across the stabilizer showed ‘0’ degrees. I placed the wing on its seating and checked that it was also at ‘0’ degrees.

I did this using an incidence meter I made myself. Here is a photo of it in position. The level indicator is a smart phoneHome Made Incidence Meter on which I have an app. that makes the phone into a spirit level. It has a simulated bubble and digital numeric indication of the actual angle (most useful).

The two Grey/Blue slides have a ‘V’ cut out, one for the leading edge and the other for the trailing edge. The deepest part of the ‘V’ each side coincides with the centre line of the wing chord. The small table on which the smart phone sits is parallel to the slide bar. This ensures that the phone reads an accurate angle of incidence for the wing.

Fixing Wings To Fuselage

Prior to finishing the wings I had marked and drilled the Nylon Wing Bolt Locationsplywood former either side of the retracted nose wheel to take the two short wing locating pegs.

The matching location for the pegs were marked on the wing face plate through the holes in the former and drilled out.  The pegs were then glued into place and the final fit checked. So far so good!

Once the underside fuselage fairing was glued in place and sanded to a smooth profile a 1.5mm (1/16″) ply plate was glued to the rear of this fairing to take the wing bolts. The hole positions were marked and 3mm pilot holes drilled through.

The wing was placed in position on the inverted fuselage and, using the pilot holes, the appropriate positions for the blind nuts were marked on the 6mm (1/4″) plywood plate epoxied into the fuselage. These pilot holes were then Blind Nuts Clamped Up Using Steel Boltsenlarged to take 6mm nylon wing bolts as shown here.

The locating holes were drilled to take the centre boss of the blind nuts. These were placed into position with a thin smear of slow setting epoxy resin applied to the face that is pulled up into the plywood. Steel bolts and washers were used to pull the nuts and their barbs into the topside of the plywood plate. these were left to allow the epoxy sufficient time to set hard.

When the epoxy had cured the steel bolts were removed and I was able to fit the wings on place and  secure them using the nylon bolts.

She’s really starting to look like a flying machine now – quite satisfying I think! I promised you some covering at the beginning of this post. Well I’m a man of my word so as a token gesture I have covered the motor access hatch, the anti-glare panel on the cockpit/battery hatch assembly and also used black lining tape to finish off the cockpit! Here’s a photo of the full assembly so far.

Wings Attached

Moving On

We’re progressing quite nicely and next time should see some serious covering done. I do hope you’re enjoying this build blog, I certainly am.

I think there is a great deal of satisfaction to be gained and I strongly recommend it to you.  To scratch build rc planes does not have to be expensive or onerous and you will learn techniques that will make you a better modeller in the long term.

If you have dropped across this post accidentally and enjoyed it, please take a look at my main website www.rookiercflyer.com. Also you can find the earlier posts in this series to see the full build log. Number one is here, take a look and enjoy.

Catch you next week.

Colin

 

April 8

Stage Four – Building Balsa RC Airplanes

Steady progress is being made on my Hawklett andJoining Wings I now have the second wing panel built and joined to the first one. The retracts are fitted into the wing panels and connected to the centrally mounted servo.

A certain amount of patience is required when building balsa rc airplanes as glues have to be given adequate time to dry. Some people are happy to use fast setting CA glues but I prefer to use White or Yellow aliphatic glues for the majority of wood to wood joints and slow setting Epoxy glue for high stress joints. These do require that the joints be left for the glue to penetrate the wood fibres and dry completely.

You will see in the photo right how I clamped the wing panels to my work table and used some old six cell Lipo packs to weight the joint down while the slow set epoxy glue dried. The trailing edges  are blocked up  so that the centre line of the ribs are horizontal all the way along each panel.

The circular item near the joint area is one of the wheel wells for the retracts. there is another on the other panel hidden from view in this shot.

Strength Considerations

Parallel chord wings are relatively simple to brace across theWing Dihedral Brace centre join line using what is known as a ‘dihedral brace’. This usually takes the form of a piece of plywood that is glued to the front or rear of the main spars, full depth across the centre joint line and extending outward several rib spaces either side

When joining swept back (or forward) wings  there is no straight line available between the two wing halves to which the brace can be glued flat. Instead the brace has to be cut to a length that fits across the centre glued ribs and is slotted to accommodate  one or two ribs before terminating at the junction of a pair of outer ribs and the main spars. Hopefully the illustration here will help you understand this arrangement.

Further strength is ensured by gluing a web of 1.5mm (1/16″) balsa between the top and bottom main spars with the grain running vertically the full length of the wing apart from the outermost three bays on either side.

Installing The Retracts In The Wing

This process is a little involved and care had to beWing Centre section With Retract Servo taken when cutting the pushrods and outer support tubes to the correct lengths. The linkage to the central servo is via ‘z’ bend 2mm rods set into Sullivan ‘Gold-N-Rod’ look-a-likes whilst the linkages to the retract activator rods are via metal clevises. These are mounted on threaded rods so that fine adjustments are possible.

When retracted the wheels fit into round wells that I made from rolled cardboard cut from the sides of a cereal packet. These are rolled round a suitable diameter spray can and glued. once dry they were mounted on false bases glued between the appropriate pair of wing ribs. The retracted Retracts & Servo Installationwheels would actually interfere with the inner ribs so cut outs had to be made in these ribs to accommodate the false bases and wells.

Before connecting the pushrods to the servo I connected up my trusty servo tester to both the wing servo and the fuselage servo that drives the nose leg. This enabled me to determine the correct way to connect these push rods to the servo and match the operation of the nose leg.

In the past, I have used a single wing mounted servo to operate both wing legs and nose leg on a trike retract arrangement. The only problem with this is that there has to be an easily connectable linkage for the nose leg when fitting the wing to the fuselage. This can be quite difficult to arrange so I decided to go for two servos connected by a ‘Y’ lead.Nose Wheel Retracted A much simpler arrangement although carrying a small extra weight penalty of the additional servo.

You may have noticed in the last two photos that there is a cut out in the centre leading edge where the wing sits against the fuselage. This is to accommodate the nose wheel where it extends beyond the limit of the fuselage underside when retracted. The sketch on the right shows this more clearly.

Adding Trailing Edges & AileronsWing Tip Block

Referring to the pictures above, you will see that I have attached the central trailing edge section and the wing tip blocks. The next step is to carve and sand these to shape prior to cladding the wings with the 1.5mm (1/16″) balsa sheeting.

The photo on the right shows one of the wing tip blocks glued in place. The full depth of the end rib at its widest part is 35mm (approx. 1 3/8″). The depth of block I required was achieved by gluing together three laminations of 12mm (1/2″) soft Balsa.Aileron Servo Plate Mount

My favoured approach to installing the aileron servos is to fit two plywood rails across one of the rib bays. The servos are attached to 1.5mm (1/16″) ply plates on their sides so that the output arm protrudes through slots in the plates. The plates screw down to these rails.

All that needs to be done before sheeting the wings is to face the frontal area that fits up to the fuselage bulkhead with 1.5mm (1/16″) plywood prior to drilling and fitting the wing locating pegs.Aileron Servo Plates

The rear wing bolt holes will be drilled through a ply reinforcing plate. This will be fitted once the wings have been sheeted and the underside fuselage fairing has been glued in place.

The ailerons are cut from 12mm (1/2″) medium balsa and sanded to the correct profile, tapering to 3mm at the trailing edge.

 

We’re Getting There

Next time I hope to be able to show you the model in some of here colours. The covering has arrived and just as soon as I have finished the woodwork I will be getting down to some serious heat shrink covering. This is not a scale model so I have adapted an early RAF/ Swiss Air Force colour scheme for my plane.

I have to say that I really enjoy scratch building balsa rc airplanes and so far this build has not disappointed. There have been a number of modifications necessary and these challenges add to the enjoyment of creating the finished article.

This is a totally traditional build process using wood and other materials common to models going back to the earliest days of rc model planes. Maybe one day I’ll get round to using more modern materials but for now I just love the feel of these traditional materials.

Don’t forget to check out my main website, www.rookiercflyer.com, especially if you are a newbie. Everything you need to know about getting started is there. This is the fourth post in this build series so if you want to go back to the beginning and follow it through from the start, go to “How To Scratch Build RC Planes“.

Come back next week for the next episode of this build blog.

Colin

 

April 1

Step Three – Scratch Building Model Airplanes

Battery hatch Cover

Last week I managed to reach the stage of finishing the basic build of my fuselage and create the cockpit/removable battery compartment cover.

As I said at the end of the post, I hoped to have the cockpit glazing finished. Unfortunately, I am a simple human with foibles and occasionally forget to check the status of certain material requirements. I have to admit to running out of canopy glue!

Who said that scratch building model airplanes was easy and always ran smoothly? I have ordered a bottle of said glue but I don’t expected it to arrive until next week.

Finishing The Tail Feathers

I explained in my last post how I created the rear end Alignment of Finfairings between the stabilizer and fin. The next step in this part of the build was to glue the stabilizer to the rear of the fuselage which, again, was explained last week.

Once the epoxy glue had dried I fitted the fin into its slot and checked for vertical alignment and that it was true to the centre line of the fuselage. This simplified diagram shows how I check this centred alignment.

Once everything was true I mixed some slow setHawklett Fin Installation epoxy glue and set the fin in its correct position. Using pins, masking tape and rubber bands I secured it and left it to dry.

Once dry, I was able to fit the previously made fairing blocks either side of the fin. a little lightweight filler rubbed into the join lines and sanded when dry gave a smooth streamlined shape ready to take the final covering.

 

Building The Wings

There is no actual dihedral built into the wings but a naturally created angle is obtained by building the wings inverted. This occurs because when the top spar is fastened down flat on the building board, the wing taper causes the underside of the wing to take on a positive dihedral angle from root to tip.

The wings are swept back at quite an angle so each panel has to be built separately. They are then glued together inverted with the spars flat on the board and the trailing edge blocked up to the correct height at the centre and at each tip. We will look at how this is done in due course.Undercart Plate

You may recall that I had decided to use a set of mechanical retracts I found in the spares box. This has meant re-engineering the undercarriage mounting arrangement. Instead of fixed leg hardwood blocks being glued into the underside of the wing, I have had to cut 6mm (1/4″) plywood plates with the appropriate cut-outs  for the legs when in the retracted position.

In the first of these posts I said that I had cut out the wing ribs following re-drawing the wing plan as a built up construction rather than balsa clad foam cores.Trailing Edge Spacing

Now I was ready to start laying down wood to create the first wing panel. The first thing to do was to pin the top main spar down over the plan, not forgetting to cover the plan with glue resistant clear polythene sheeting first.

Next I cut two small blocks of scrap balsa to act as spacers for the trailing edge. These were cut so that when spaced off the bench, the centre of the trailing edge was at the same height as the centre line of the ribs.

Once all of the ribs had been glued to the top spar and to the trailing edge, I fitted the bottom spar (remember the wing is upside down so this spar is on the top). When all joints are firmly set the leading edge was glued to the front of the ribs.

It is worth mentioning at this point that the root ribsBasic Wing Structure (the ones that will be glued together when the wing halves are joined) are from 3mm (1/8″) plywood as are ribs 3 & 4 to which the retract plate will be glued.

So far, so good! The wing is now a strong rigid structure ready to have the retract unit and pushrod fitted. Structurally it will be finished with vertical 1.5mm (1/16″) webbing between the main spars. A central retract servo housing and supports for the aileron servo mounting plate will be fitted. Once these are all fitted and the two panels have been glued together and braced, the whole wing panel will be covered with 1.5mm (1/16″) balsa.

In the photo (right) you can see the cut outs for the retract plate, pushrod clearance and for the wheel-well. Its interesting to see that although the wing tapers quite dramatically, it looks to be almost parallel because of the angle at which it was taken.

Till The Next Time

Next week I hope to have built the second wing panel, joined the two together and fitted the various accessories within the wing structure ready for the covering.

My fresh supply of canopy glue should be available so that I can fit the rest of the canopy glazing to the battery compartment cover.

I hope you are enjoying following my explanation of scratch building model airplanes. If you have just discovered this post, please take a look at the previous two posts covering the start of the project, starting withhow to scratch build rc planes

Please feel free to share this post and the others with anyone you think could benefit from its content. If you are new to rc model planes and want to know how to get started successfully, please visit my website www.rookiercflyer.com. You will find everything you need to know.

Catch you next week.

Colin