I’m not trying to brag, but I’ve been building and flying RC airplanes for 26 years, I got my first control line airplane more than thirty years ago! I still remember that first plane – a Carl Goldberg Lil’ Whizard, and a COX .049 Babe Bee to power it! My dad and I built that little ‘Ukie’ and flew it in the cul-de-sac where we used to live. It was the summer of 1987 – I turned ten that summer, and still remember it well….
Wait a minute, we’re talking GIANT scale here, not 1/2 A airplanes!
I bring this up to make a point. I know that I tend to forget that there are modelers that are still new to different aspects of the hobby, and I’m sure there are lots of other guys just like me. We think that everyone should know just as much about the hobby as we do! So, with this in mind, I’m keeping my ‘How Do I…’ string of articles expanding. I plan to cover as many different topics as I can in our hobby! Of course, I don’t know everything there is to know about the hobby, but I’m going to share the things that I do! Hopefully, I can give some pointers to those just getting into new areas of RC airplanes. This article is going to focus on giant scale aircraft, but I’m going to split this topic into three different articles. Why? Well, I’m glad you asked! The reason is this – setting up some giant scale aircraft are easier than others. Larger, more complex aircraft have different requirements than smaller planes. So, before we get into the thick of this, we need to answer one more question…
What is Giant Scale?
That’s a great question! Thankfully, there’s a relatively simple answer! Giant scale is defined by four simple criteria:
1) Monoplanes must have a wingspan of at least 80″.
2) Biplanes must have a wingspan of at least 60″.
3) Jets must have a combined width and length of 140″. (wingspan and length of fuselage added together must be at least 140″)
3) If none of the above is true, the airplane MUST be a true 1/4 scale.
If an airplane does not meet at least one of the four criteria above, it will most likely not be considered giant scale.
What is This Article’s Purpose?
The purpose of this article is to help modelers get an idea of larger aircraft requirements. There are certain things that we will do differently for a large airplane that we won’t do for something smaller. At the same time, setting up a 30-45cc aircraft is going to be different than a 50-70cc airplane, and also different than an aircraft that would require an engine in the 100cc range. I’m writing this to share my knowledge with the ‘next generation’ of modelers getting into giant scale aircraft. Since the 30-45cc aircraft will be most similar to what newer modelers are currently flying, I’m going to start here. Following this article will be 50-70cc, and then finally 100-120cc! Now, as much as I would love to keep going, the largest plane I’ve had to date is a 30% scale Stearman biplane. I’m going to stick to what I know…. Hopefully, I’ve got your interest piqued – if so, read on!
The first thing you’re going to want is a relatively large building/assembly area. I have a shop in my basement, and I will admit that it’s not nearly as large as I’d like, but it gets me by. Unfortunately, I am limited to 7 foot ceilings in my basement, so assembling large airplanes can get a little difficult. Many of my larger projects have their final assembly done out in my garage.
My bench is a full 4 feet wide by 8 feet long, and was made by me. The frame is made from 2×4 lumber standing on edge, with a sheet of 3/4″ OSB (chip board) on top of the 2x4s. A 1/4″ Melamine top layer makes for a nice bench top, especially for all the photo work I do. The legs are made of 2×4 lumber as well, and screwed together in an ‘L’ configuration. I’ve used this bench for close to 10 years now, and it’s still flat – If I ever need to true up the top, an additional frame member can be added with two more legs.
Assembly/Installation Tips and Tricks
Now this may seem like a silly photo and comment, but it’s VERY important – READ THE MANUAL! The manufacturer sends it with the airplane for a reason….
Vibration insulation is important! Foam rubber and hook n loop tape are great ways to add vibration insulation to key components. Batteries, receivers, and ignition modules will all last longer when they are isolated from the vibrations of an internal combustion engine. Of course, if you’re converting a large aircraft to electric power, there’s less concern with vibration.
Pushrods, Clevises, and Control Horns – All of the components should be up to the task required. The manufacturer should supply adequate hardware, but if you’re ever concerned, upgrade to aftermarket hardware. The BEST place I know of to get hardware is DuBro. DuBro is a company dedicated to the RC hobby, and has a vast selection of hardware for models of all shapes and sizes. If you need it, DuBro most likely has it!
Another DuBro Product I use on every aircraft is their socket head servo screws. These screws are great!
For the Great Planes Avistar 30cc ARF, the pushrods are threaded on only the tail end, and the end inside the fuselage gets a solder-on clevis. Stay tuned for another ‘How Do I…’ article on soldering clevises!
Also important for giant scale aircraft is proper servo selection. Usually, the model’s manual will call out specific servos to use for best results. If you plan to use different servos, make sure that what you plan to use is equivalent in torque, speed, and voltage. Metal gear servos are always a good choice for giant scale, but may not be needed in every situation. Choose your servos carefully, as they are important!
When I originally assembled the Great Planes Avistar 30cc ARF, I installed the new RCGF 35cc Rear Exhaust engine. The rear mounted exhaust made it ideal for fitting the engine inside the Avistar’s cowl. The engine mounting had to be worked out, as it was slightly different that the DLE and O.S. Engine mounting patterns that had been pre-printed on the firewall. Believe it or not, this is NOT a difficult task! With a little forethought, finding the bolt hole locations is pretty easy!
Now comes an important lesson – thread locking compound is your best friend when it comes to giant scale aircraft. There are plenty of places to get this, and many different types that you can use. Most of the time, you’re going to want the ‘Blue’ compound, and I like ZAP Z-42 Blue Thread Locker. It keeps nuts and bolts tight, but will break free using hand tools when needed.
One of the main differences you may notice is the aluminum stand-off engine mounting. This is different than the standard ‘beam style’ engine mount associated with two and four stroke glow engines.
I cannot stress enough how nice it is to use ball links on the throttle and choke arms on the carburetor. These allow a larger range of motion than a standard clevis! If your kit or ARF does not include them, check out DuBro for a complete selection!
Even with the ball links, proper alignment of the throttle and choke pushrods is crucial for smooth, bind-free servo operation. One of the best tools I own is a 3/16″ drill bit that is 12″ long – this makes getting into tight spots a lot easier! The Avistar 30cc ARF includes parts to add a pushrod and servo for the choke – if your particular airplane does not have this, don’t worry – there’s plenty of ways to make a manual choke rod!
Final engine assembly and installation is important – again, use plenty of thread locking compound, and make sure all your components are secure. Zip ties are also important to securing items, such as the spark plug wire and other ignition wiring.
The best engine in the world will not run well at all if the fuel system is not assembled and installed properly. Soldering the barbs on the fuel tubing is a great way to help secure the Tygon fuel line to the fuel tank stopper. The fuel line barbs are available from DuBro, and can be found here. As you can see, I prefer a three-line setup, which allows a separate filler line. A piece of 1/4″ foam rubber helps to dampen the vibrations to the fuel tank, and zip ties help to secure and keep the fuel lines organized. I also use coax cable clips to hols the vent line in place. These are available at your local home improvement store – I found them in the electrical department at my local Menards. The filler line stopper assembly is from DuBro, and is called the Fill It Filling System.
Whether you’re installing a cowl, or any other screw into wood, there’s a correct method. I start by drilling a hole slightly smaller than the screw, followed by turning the screw into the hole I just drilled. The screw is then removed from the hole, and a few drops of thin CA is applied to the hole. The thin CA soaks into the wood in the hole, and hardens, creating a hole that is tougher than wood alone. It’s also good for holding screws tight with the added vibration of a running engine.
Once the cowl has been installed, the Propeller and spinner (if a spinner is necessary) are installed. The RCGF propeller hub has four machine screws to hold the prop in place. There are prop drill guides available, but the front prop washer, machine screws, and a drill press are all that is needed to drill the holes in the propeller. For this installation, I drilled out my Falcon 19×8 Beechwood prop. Falcon Propellers are available at www.justmodelprops.com. Falcon props are the only propeller I use, and they are a great prop at an exceptional price!
A few more drops of ZAP Z-42 Blue Thread Locker were applied to the four propeller hub machine screws, and the screws were then secured. The aluminum spinner was included with the Avistar 30cc ARF, and really added a nice touch!
High quality, and heavy duty servo extension wires and switches are always a plus when setting up a giant scale aircraft. Not that there’s any good place to skimp when assembling a giant scale plane, electronics is definitely one area to purchase good equipment!
Another good practice to use is labeling servo wire connections – adding labels to your connections will help to get the correct servos and wires connected. This will definitely help to eliminate an area that can cause crashes For the Avistar 30cc, the wing has two aileron servos, as well as two flap servos. If the wires were not labeled, it would make connecting them a guessing game!
When You’re Ready for the Field…
You’re finally bringing your giant scale plane to the field for the first time. There’s probably a few things going on – your excitement of a new model is most likely at an all-time high, and your fellow club members are excited to see your new model as well. This is a situation where mistakes can happen. Remember when I mentioned labeling servo wire connections – this really comes into play now – it’ll be a lot easier to make sure everything is correct if it’s labeled! But… This is also a great time to step back for a few minutes and double or triple check that you’ve done your field assembly correct. After all the work you just put into putting your new giant scale plane together, it would be a shame to lose it due to missing something at the field!
So now that you’ve checked and rechecked everything, it’s time for that maiden flight. As with any other model, a range check should be done with your radio system. Do the range check twice – engine off, and engine running. You’ll want to make sure that there’s no interference from the engine’s ignition system. Now, most modern ignition systems are not causing interference, it’s always a great idea to check!
The range check is done, and your’re ready to get the plane in the air – top off the fuel tank, calm your nerves if necessary, and go fly!
For the maiden flight, it’s always been my practice to fly with a friend. I’ve had planes that were so far out of trim that it’s easier to have a friend adjusting the trim while I concentrate on keeping the plane from hitting the ground. My buddy Jim Buzzeo has been my flying partner for longer than I can remember, and I won’t fly a maiden without him!
Here’s a few of the photos from a successful maiden flight of the Great Planes Avistar 30cc ARF!
If you’ve done everything according to the manual, and followed my suggestions, you should have a well set up model with a dependable fuel system and engine! These qualities in a model, along with a few flights, will make flying your new giant scale model a pleasure!
Of course, radio system selection is also important, mainly for the number of channels required. For the Avistar 30cc review, I used my Futaba T10CAG transmitter and R6014HS receiver. For the review, I had each control surface on its own channel, as well as the choke and throttle. This used 9 channels for setup, and required some programming. In the end, it was great, because I could adjust anything I wanted individually! The most important part of radio selection is to use what makes you feel comfortable. Stepping up to a giant scale plane adds to nerves, and if you’re trying to figure out an unfamiliar radio system AND a new model, it can be a lot to deal with!
And now for my MOST important recommendation…
Don’t forget to HAVE FUN!
Thant’s all for now. From my shop to yours – Happy Landings! -GB