Upgrades and Changes

After the maiden flight it was evident that my Boomerang was nose heavy. My plane is not the only one, so it was good looking at how other club members resolved this. I had already moved the battery as far back towards the tail, which included 38 grams of extra lead. I then removed the lead and located a strip of stick on weights from a tyre shop. These were cut in half and placed under the lower horizontal stabiliser. This immediately improved the CG balance and the second flight went very well. The wind was blowing, and my plane had no problems at all.

The most recent change was upgrading the Spektrum AR400 receiver to an AR6210. The AR400 is not a long range receiver and after hearing about planes flying away when out of range it was an easy decision. The AR6210 has 6 channels and a data port which can connect to the Spekrum TM1000 telemetry module.

A Du-bro exhaust deflector was fitted to help keep all the exhaust oil and fuel off the plane during flight.

The aileron receiver cable now has an extension to help prevent the receiver pins from getting damaged. It is also easier to connect the wing.

Future upgrades may include the TM1000 telemetry module and GPS module to help locate my plane.

 

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Thank You.

My Boomerang is complete and so my next challenge is learning how to fly. I must thank a few people. Patsy and Richard for all their helpful information. Brian for all his dedicated help setting up my plane in his workshop. Graeme for running in my engine and pre flight test. Kev for doing my transmitter range test. Stephen for testing my plane on her maiden flight.

 

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Maiden Fight

I spent the morning with Brian, an experienced club member testing the OS Max 46 AX II engine. All went well after checking various items. This included the tank, spinner and propellor settings. The engine ran well and so the next step was taking my Boomerang to our club.

I had assistance from several club members which included checking the balance, transmitter range test and running in the engine. This all went well.

Another experienced club member, Graeme then tested my plane before her maiden flight. After several hours working on my plane, it was finally flying. I still need to adjust the balance as it is slightly nose heavy. My Boomerang was tested by Stephen who has lots of experience with glo engines. It was very rewarding seeing my plane fly for the first time.

 

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Pre Flight Setup and Trim.

I spent an evening with an expert who gave me lots of tips, and changes to improve my plane. These included changes to the fuel tank, switch, battery, dope sealing, landing gear collets and more.

I still need to complete the pre flight trim and engine run in. If all goes well this should happen soon, and my new plane will be in the sky this weekend.

The trim info and final setup will come soon.

 

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Installing the Engine & Propellor

I bought an OS 46 AX II engine. I already own an OS 29 MAX III and think they are great. The user guide tells you to measure 110mm from the firewall and this would be where the propellor is. This could vary depending on your engine size and I am not sure about the P factor caused by this powerful engine.

The manual also indicates screwing the engine into the plastic mount. My mount is well and truly set after using thread lock on the bolts. I need to ensure the holes drilled are 100 % correct. I have bought 4 hex bolts with self locking nuts.

With this is mind, I will be getting a local club member to help install my engine. I am not sure if my 11 x 6 Master Airscrew propellor is balanced, so will check this as well. Hopefully the spinner will fit without slipping when the throttle is high.

Another issue is the fuel line. I fitted a fuel inlet on the side of my plane. The fuel hose does not run straight from the tank, and the filter makes this even more tricky. These are all questions that will be better answered by an experienced club member.

The engine was fitted after painting dope over the mount and engine area. The dope will dissolve the colour on the film, so be careful. The holes did not line up exactly and so the engine is about 3mm to the right. I think it may actually help improve the P factor issue. Time will tell.

The propeller was gently sanded on the edges and fitted with the spinner. I had to increase the propellor hole to fit the engine perfectly. The spinner is not a great fit, so still need to sort this out.

I still need to setup the throttle servo and push rod.

 

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Working with CA and Epoxy Glue.

After watching the Youtube movie "All about epoxy glues for RC models" it became evident that having a high quality epoxy is important. I bought all my ZAP glue from my local hobby shop and was pleased with the results.

In the end I bought the 30 & 5 min Epoxy, Medium and Thin CA, Thread Lock and Canopy glue. It all adds up, but fine if you are building other models.

The epoxy was easy to use and mix, and cleaned off the plane with nail polish remover. (Acetone)

The CA glue was more of a challenge. The thin CA runs very fast and it is easy to get on your fingers. In a panic trying not to glue your fingers, you may end up glueing things around you. Check the glue bottle does not have any excess CA before pushing down the cap. Mine did, and sprayed CA glue over my plane.

I would suggest buying the small bottles of CA. They need to stay in a fridge and do not last long. Make sure you put the bottles in a container to avoid damaging your fridge shelf.

I used a spot of CA glue on screws that are permanent. The servos holes were filled with 2 drops of thin CA and left to dry. This was after the thread from the screw was made in the wood.

The canopy glue was useful for glueing foam rubber inside the plane

 

 

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Installing the Servos.

I bought the JR 519 and 539 servos to ensure they would fit. They are also a good brand. Fitting the brass collets and grommets was easy after the first servo. Fitting them was easy. The photo clearly shows the location. The rubber grommets are the wrong way round in my photos, and were all reversed. The little lip needs to be against the servo.

I presume the horn was cut in half, as these servos do not come with the ones shown. I cut them in half as shown in the guide. This was done when joining the push rods.

After reading the article in the RCMN magazine, I added the 2 drops of CA glue per hole. This involved removing the servos and making sure the CA glue did not fill the hole. The glue has to cure before putting the screws back in. Failing to do this would make them a permanent fixture.

 

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Installing the Receiver

My Spektrum DX6i kit came with 2 x AR 400 receivers. The box also included the Phoenix 4 simulator and DX6i transmitter. The simulator works like a dream with the DX6i when connected to a large TV. I have upgraded the AR 400 to a AR6210 6 channel long range receiver. This was after hearing about short range planes flying away. The AR6210 will work with future telemetry modules.

I bought a 6 volt 5 cell 1500 mAh battery which had the correct connector to my switch. The binding process was easy after following the instructions. Once done I connected my servos and noticed they set to their normal position. This required me adjusting the horn again.

My battery charger was a middle of the range unit, that can charge a number of types and can run off 12v. This seemed logical if you are at the field and need to charge something. After setting all the correct charging settings. I.e Amps and Cycle rate, it was a matter of holding the start button in until it started.

It is possible to charge your receiver battery with the transmitter charger. This would take longer, however could save money.

The receiver and battery are protected with foam rubber to avoid any vibration that could cause a problem. The AR 400 aerial is very short, so fitted as required.

Testing the servos worked well and now they need to be adjusted for trainer mode.

 

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Fitting the Pushrods

I ended up upgrading the horn connectors to EZ Clips and so the rod size increased as well. They are still a perfect fit in the tube, and the correct fit on the Du-Bro 2-56 Kwik Link.

I marked the push rods as shown in the manual and then cut and bent them to the 8mm requirement. I had to increase the horn hole size so that the rod would fit. Everything worked out fine.

Before I started, I used masking tape to ensure the elevator and rudder were straight. After fitting the receiver I found the servo position changed, and so I had to make a few adjustments.

 

 

 

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Fitting the Control Horns

The control horns that came with my kit were not the same as the guide. They had 3 holes each and looked more like a triangle. They still fitted much the same. The elevator horn ended up a bit off centre even after trying not to misalign the holes. I upgraded the push rod connectors to EZ clips. The connector did not fit on the first horn setting, and so I moved it. This could easily be fixed, should I need to.

With the rudder, I connected the control horn to the push rod, and made sure it lined up. This way it would be a good fit. I drilled it whist connected and fitted the small bolts and screws.

Lastly I carefully added some ZAP thread lock to all the bolts before making them tight. I still need to cut back the tips of the bolts.

 

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Fitting the Vertical Stabaliser

This was not that difficult. I made sure the correct amount of covering was removed and needed to ensure a small piece remained for the very end.

After adding the 30 min epoxy, the Stabaliser was fitted. I added some canopy glue under the thin white part that sticks out over the fuselage.

Using various methods, I made sure the glue set with the Stabaliser in the correct position.

 

 

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Fitting the Horizontal Stabaliser

The servos are almost in and the final install will follow after this post. The first step when fitting the Stabaliser is removing the covering so the epoxy will make a strong bond.

You measure across the Stabaliser and find the middle. Then use a right angle and draw across the wing. I ended up checking this from other parts of the wing to make sure it was 100% accurate.

The next step is carefully pushing the Stabaliser into the fuselage after you have removed the fuselage covering. I used a hobby knife and ruler to gently cut the covering. I did not want to damage the fuselage.

The first time I pushed the Stabaliser into the fuselage it sounded like it cracked. It did not, so I am not sure what the sound was. I checked it to make sure everything was ok.

Once in, I aligned it with my markings and then used a pencil to mark around the join. This was easy. After removing the Stabaliser, it was easy to gently cut away the covering.

Next will be glueing the Stabaliser into the fuselage and making sure it is exactly correct.

 

The process was relatively easy. I just made sure everything was equally measured. A tape measure worked well, and the Stabaliser glued well. You do need to use nail polish remover to clean the extra epoxy as it comes out.

 

 

 

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Missing Parts from the Kit.

I was surprised that the manual tells you to fit the switch, but does not include it in the box. The exact holes are already cut out for you. I spoke to another person who built this plane and they confirmed that it was missing.

Maybe the quality is poor and you would be better off with a more reliable one. I have contacted Seagull for an answer.

The other item missing was one of the push rod connectors. You should have 3 and I only had 2. One of the packets had a hole at the bottom, so I presume the part fell out at the factory. I bought another brand for the servos from a local hobby shop, however the ones provided looked better.

This kit needs a check list of parts. This way you could check for missing items before you build the plane. I have started one which is included with the costs spreadsheet.

 

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Installing the Fuel Tank

This was relatively easy. The guide first tells you to bend the plastic stopper pipes, then heat them. I used a heat gun and noticed they started to melt rather quickly. It may be worth keeping the heat low. I did not want to use a lighter, but suppose it would work. I had the remove the tank and increase the bend. The vent pipe had 45% cut made to it to prevent it from getting blocked on the top of the tank.

The diagram shown of the internal tank configuration is not the same as the stopper. The lower filling tube will not go to the bottom of the tank. This is not a problem anyway. The top vent that connects to the silencer does need to be correct. I made sure the brass fuel pickup was at the end of the tank, to make sure it will always work.

I had trouble getting the silicon tube onto the brass fuel pickup unit. The guide does not specify a fuel line size. Mine seemed ok, but tore when first fitted. The second attempt was fine. The other pipes were easy to fit. I did mark the pipes as suggested to identify them once in the plane.

A recent article suggested adding protective foam around the tank to prevent air bubbles. These apparently appear if the tank moves in the plane. I have added foam to help prevent any movement, however not like my photo. The push rods would be in the way. I cut the foam and fitted it under the tank.

Before fitting the tank, I painted SIG dope inside the fuel area to prevent any damage from the engine oil and fuel during flight.

The last part is glueing in the piece of wood around the tank. It only goes one way. The plastic aerial tube fits on the left, if looking from the front of the plane. The pushrod goes through on the lower right. The little block of wood keeps everything in place.

I may still fit a fuel filter like the JR version that eliminates bubbles.

Next is the servos.

 

 

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Installing the Fuel Tank

This was relatively easy. The guide first tells you to bend the plastic stopper pipes, then heat them. I used a heat gun and noticed they started to melt rather quickly. It may be worth keeping the heat low. I did not want to use a lighter, but suppose it would work.

The diagram shown of the internal tank configuration is not the same as the stopper. The lower filling tube will not go to the bottom of the tank. This is not a problem anyway. The top vent that connects to the silencer does need to be correct.

I had trouble getting the silicon tube onto the brass fuel pickup unit. The guide does not specify a fuel line size. Mine seemed ok, but tore when first fitted. The second attempt was fine. The other pipes were easy to fit. I did mark the pipes as suggested to identify them once in the plane.

A recent article suggested adding protective foam around the tank to prevent air bubbles. These apparently appear if the tank moves in the plane. I have added foam to help prevent any movement.

The last part is glueing in the piece of wood around the tank. It only goes one way. The plastic aerial tube fits on the left, if looking from the front of the plane. The pushrod goes through on the lower right. The little block of wood keeps everything in place.

I may still fit a fuel filter like the JR version that eliminates bubbles.

Next is the servos.

 

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Installing the Landing Gear

After correcting the Aileron pushrod problem, I moved onto the landing gear. The user guide gets worse, as it shows removing the covering in 2 places. This is wrong. You only remove the relevant covering depending on your wheel setup. I did not use the tail dragger, so did not need the front covering removed.

After removing the covering it was evident that the wheel landing gear wires will not sit flush and protrude a little about the groove. I cut the remaining covering on the edge to help get the wire to sit more flat. The plastic straps are flat, and bend once pulled down with the screws. I may add some CA glue to the screws to avoid loosing my landing gear. The user guide has labelled a Plastic Trap instead of Strap.

Fitting the wheels and landing gear was easy. I upgraded my wheels to lightweight Du-Bro 2-1/2 rubber tyres. The required 3/32" drill bit was a perfect fit for the screws.

The front wheel was relatively easy to install however the push rod connector is not long enough to fit through the horn. The tiny bolt hardly fits on the screw, so I will need some CA glue to keep it from falling off.

Next is the engine mount and Fuel Tank.

 

 

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Installing the Aileron Linkage

My JR servos and OS engine arrived today. The JR servos have no instructions and the Boomerang user guide photographs are hard to see in B/W. It is well worth downloading the colour PDF version to zoom into the colour photos.

After a Google search I found out the brass collets are installed from the bottom up. This is not in the guide, however is important to stop the collet cutting into the balsa. This prevents extra vibration on the servo. The photo below clearly shows them fitted from the bottom up. I fitted the rubber grommets the wrong way round. I removed all my servos and turned them so the flat part is facing in.

Another tip found online was cutting the covering just in from the servo mount. This looks better, and prevents anything going into the balsa. Fitting the JR 539 was easy as it was a perfect fit without having to cut any part of the wing. The only extra cut was for the servo wire as shown in the guide.

The 5 minute epoxy set quickly, however I was unable to get the mount to make a perfectly flat bond. I did not want to exert too much pressure on the wing whilst it dried. It still looks good and will work fine.

Using the 1/16 drill bit worked well. I just made sure I did not drill too far into the wing. The screws pulled down without any fuss. I have not glued the servo into the mount as suggested by someone. I would like to get a second opinion on this. After reading RCMN, I have added the 2 drops of CA glue per hole after the screws have made a thread in the ply. The glue needed to set before putting the screws back in. I made sure the CA glue did not fill the hole with a paper clip.

Next was adding the pushrod wires. This seemed a bit confusing as they are so long, and you only use a small amount of the rod. The threaded side was easy to understand however the connectors provided are not the same as the guide. I am not 100% happy that these will be good enough as they look very weak. I had to drill the horn hole out to get the connector to fit. The tiny plastic pin looks very fragile. I may replace these before I fly my plane.

I had to remove the plastic connector from the aileron rods to connect the push rod connector. It was not easy getting the plastic pin in the hole, and it looked like it was going to break. After screwing the 2 connectors back onto the rod, I bent the tips of the rods to help screw them in. This worked fine.

The next step was cutting the rods and fitting them. I used a Dremel with a small metal disc to cut the rod. I think it may be best finding something that can cut the rods in future. The sparks may damage the wing if not careful. I still need to get some advice on finishing this servo installation. I will need to align the aileron and then ensure the connectors and horn are all setup correctly. I am sure this can be trimmed on the transmitter, however will make sure it is all correctly installed.

After looking at the colour version again, I see my installation was wrong. The plastic connectors used on the servo and push rods are different. You a ment to slide a small plastic ring over the side that the rod screws in. The other side should bend down into the servo horn. I will need to buy 2 new push rods and change this.

Till then

Sean

 

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Building a Boomerang II 40 - Glueing the Wings.

1. First Part of Dihedral Brace.

After trying to figure out the user guide, I thought it may be better to get some advice from the RCGroups Forum. The guide is confusing, and hopefully I have figured this out. The article in this months Radio Control Model News was a bit brief with regards to glueing the wing together.

I measured the aluminium dihedral brace to +- 21.25 mm and marked it. Then mixed my 30 min Z-Poxy. I used way to much, so will use less next time. After covering the bar, I found an old blind rod, and covered the tip with glue. Then used this to apply glue within the dihedral hole, rotating it inside.

Everyone was right about epoxy pushing out when you insert the brace. I had my wife's nail polish remover close at hand and used it with paper towel to clean up the excess glue. My only concern was joining the wing together to make sure the brace set at the correct angle. Any excess epoxy would glue the wings together and I did not want this. Trying to figure out the masking tape process in the guide made no sense, so it was time to improvise. I made sure that even if any epoxy leaked, it would not bond with the wing.

I used 2 small plastic clamps from Bunnings to help keep the wing together whilst the dihedral set on one side.

2. Second Part of Dihedral Brace.

Everything worked out well after removing the masking tape, and so the next part of the project was to glue the wings together. The procedure was much the same as the first part, however this time the epoxy needed to go between the wings as well. Trying to work out how much glue to use is hit and miss.

I mixed the right amount this time, and coated it on the rest of the dihedral using my ice-cream stick paddle. Then repeated the process with a rod and glue into the second wing hole. Epoxy was applied evenly on the one side of the wing ensuring I had enough to make a decent bond.

The wings joined easily together with a small amount of epoxy oozing out. This was easy to clean up with nail remover once the masking tape was removed. I only waited about 15 min before I removed the masking tape just in case it started bonding with the wing.

I did sit on my couch holding the wing together to get the best possible join. The process was easy and so I just need to wait for my servos to arrive.

Till then

Sean

 

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Boomerang II 40 Total Costs in $AU.

This post will include all the costs involved from building to flying. I will add links to the relevant bought parts as well. I am no expert, so my views are made from researching websites, magazines, forums, social media and talking to people. A spreadsheet of total costs is available here. It is a lot cheaper finding a second hand trainer as the hidden costs add up fast. The one below was only $220 for a Boomerang I, excluding the radio.

 

1. Boomerang II 40 plane: $129 from ModelFlight. (Postage was free with other items included over $200) Reason for purchse: The Boomerang is the most popular trainer as mentioned on several websites and magazines. I found excellent reviews on using this trainer to start flying. The local aeroclub has a few. I like the colours.

2. JR Servos: 519 $19.99 and 539 $21.99 from ModelFlight. (2 each as shown in the instruction PDF guide) $83.96 for 4 x analog servos. Reason fo purchase: JR have a good reputation and the servos would fit into the provided servo mount. As a beginner, I could not justify $36 per servo. You could buy digital servos, however I wanted to keep things simple and reduce overall costs.

3. OS MAX-46AX II with 3071 Silencer Engine: $149.99 from ModelFlight. Reason for purchase: I love OS engines as have others from my Control Line planes. This engine was given a good review in Issue 119 of Radio Control Model News. (Page 32-33). I have done some extensive research into the history and engineering of nitro plane engines. Ron Chernich Model Engine News. DKD

4. ZAP Z-Poxy 30/5 min and Zap Thin CA Glue: I bought all my glue from Bundy ToyWorld. 30 min was $29.99 for 4 Fl Oz. $7.99 for 5 min 1 Fl Oz and $6.95 for the CA Thin glue. Reason for purchase: After watching Youtube clips on Epoxy quality, you do not want rubbish glue holding your plane together. Epoxy should bond to an icecream container lid and not peel off. The CA glue is easy to use and bonds quickly into the hinge. I would not want a hinge to fail mid flight.

5. Du-Bro 2-1/2" Treaded Lightweight Wheels: These were bought from Bundy Hobby & Toys at $10.95 per set. You need 2 sets if you plan to replace all 3 front wheels. Reason for purchase: This was after reading an article on the Hamilton Flying Club. Basic ARTF Assembly of the Boomerang. I should have bought 2-3/4 but could not get them locally.

 

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