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SIG 60in Four-Star 40 kit guide
Contents
Introduction
When Hazel Sigafoose hired Bruce Tharpe to design what ultimately became the first in a line of kits, he created a 40-size sport model. Spanning 60in, which with a 10in chord meant it sported 604in² of wing area, he create a masterpiece of sport flying that may never be surpassed.
I know because I’ve built two and love the model for what it is to this very day. So when a fellow called to chat with me about servos for one of these things, I pretty much knew what would work both servo-wise and engine-wise.
I shared my thoughts but engine-wise he had other ideas, an electric motor, instead. Far from disagreeing with him, I was enthusiastic for his plans.
And to my complete satisfaction, he took my advice and instead of equipping it with standard class DS90DLHV servos, he opted to spend a little bit more. My preference are the DS100DLHV micro servos, instead.
Why? Because the already lightly built airframe turns out even lighter!
Background
My SIG Four-Star 40 was equipped with an OS MAX .48 four-stroke engine, and my second, an iterated version, the OS MAX .52 Surpass. Both ran on 5% SIG nitro fuel (which, with a touch of castor oil ensured protection in the event of a lean run).
That this came at the cost of some mild staining on the muffler is more than offset by the wonderful smell of nitro and castor based-fuel. Fuel whose smell screams model airplane! The model performed superbly with both engine variations. As have ones I’ve seen and flown equipped with a 2-stroke .40 and .46 engines. Honestly? I preferred the four stroke. They just seem to better suit the airframe.
And while I haven’t seen one fly with an electric motor, my customer reports it flies like a dream. Somehow I’m not surprised and suspect Bruce, looking down on modelers from his roost in heaven, is pleased (Bruce Tharpe flew west. September 2024, may he RIP).
In fact, if it were to some to pass that by some decree I could only have ‘one’ model airplane ever again, Bruce’s wonderful Four-Star 40 would be my choice.
Up next is building the model. And if you’ve never built a model airplane, then quite honestly, this is an excellent model for it.
Stabs
Putting this model together begins – like with almost every model airplane build I’ve ever seen – with the tail feathers. Comprised of just a few 1/4″ thick balsa parts. Once glued together, they’re pinned down and left to dry.
Afterward, the edges are rounded off with a sanding block equipped with 120-grit sandpaper. This gets the profile to the approximate shape. This is then followed up with 180-grit to smooth the wood grain. And the final sanding is with 220-grit paper.
Note: the tips are glued on cross-grain to keep the stab from warping.
Wing
Next up is the wing. The wing halves frame up quickly. After pinning a spar in place over the plans (lay down wax paper first to keep from gluing parts to the workbench), add a piece of trailing edge sheeting next, then standing up the ribs takes but a few minutes.
Next, comes the leading edge, the upper spar, the leading spars (ahead of the main spar in lieu of sheeting), and then the trailing edge and center section sheeting. Add the wingtips and the wing half is complete.
Repeat for the other side.
Once the individual panels are framed and sanded, they’re joined with epoxy. Note the aileron torque tubes at the trailing edge and the 1/4in dowel to secure the wing to the bulkhead at the leading edge.
Relying on forward spars instead of sheeting, Bruce’s design genius lay in leaving off everything that wasn’t required in order to end up with a supremely light structure.
Fuselage
After the stabs have been built, and the wing halves are joined, what’s left is the fuselage. A pioneer of tab-lock construction, Bruce’s design goes together in minutes.
Merely with the aid of rubberbands to hold the formers and sides together, it comes out perfectly straight. The tab locks mean you won’t build a banana, that’s for sure. And it’s super light, also.
Trial assembly
Seeing the model in the bones is a special moment. It’s when all the hard work comes together and reveals what it is you have wrought.
Covering
The next step is covering the model. Before this can proceed you have to decide, iron-on film, iron-on fabric, or perhaps the old-school classic silk-and-dope. No clue what this is? This article may help!
Electing to go with iron-on fabric, it’s my opinion the model flies better than with film. Why? I’m not really sure but suspect the slight surface roughness works similar to the dimples in a golf ball. Yes, I’ll admit I could be out in left field on this one, but this is my theory.
Avionics installation
Servo installation is duck soup because you merely screw down a pair of servos for rudder and elevator to the mounting rails within the fuselage. Note the supplied mounting screws as well as the screw for the servo arm require a 2mm Allen driver.
There’s a right and wrong way to install servos. Review this article.
The wing servo install is even easier as per the plans, the build has a single servo within the wing center section driving two strip ailerons through torque tubes. It doesn’t get an simpler than this!
The switcheroo . . . from single-servo to dual-servo ailerons! I was surprised to subsequently receive this next photo as it shows a switch from what’s called for on the plans. Instead of a single servo driving the torque tubes, the builder elected to implement a dual servo installation. Easy enough, just mount the two servos side-by-side and drive each strip independently.
Knowing the builder had a singular focus on saving weight, I was a bit surprised, but quietly pleased. This, because using dual servos gave him increased versatility of flight. Two servos allows the flaperon function, which can be great fun to really float the model along.
Final assembly
When you’re not painting the model to save weight, opting for simple red and white checks for trim to aid in orientation, is wise. This model is finished, and based on the dates of the photos, he spent about as much time as I did, a leisurely two weeks from start to finish.
When I did mine, I was fooling around with it after work, and I bet it was the same with him! Looks nice, doesn’t it?
Avionics
A standard build would see you selecting DS90DLHV servos. A lightweight build the DS100DLHV shown. Alternatives abound as these are two of the four servos comprising what we call internally, the Century class.
And nothing tricky about this Century designation because all four servos output in the range of 100oz-in. Since there are 100 years in a century, hence the name!
From left to right, the DS105CLHV sub-micro, the DS100DLHV micro used in this build, the DS110CLHV mini, and finally, the DS90DLHV useful for a standard build.
Battery pack
Selecting a battery pack for an engine powered variant is easy. With 4-5 micro servos, the B2S850 is all you need. Opt for a B2S1800 if you have the disease. E.g. anticipate long days at the field.
This would be ‘my’ choice because I have ‘very’ often logged 8 flights on any given day. This is just one of those models that begs to be flown, believe me!
Switch
The avionics switch is important. And in my opinion, one switch is not enough because then you’re at risk of switch failure. The benefit of experiencing switch failure when you have two switches in parallel is it’s an inconvenience instead of a crash. After all, odds of both independent switches failing on the same flight are astronomical.
Anyway, whether you use a pair of individual switches you buy at a hobby shop, or a singleton of our illuminated dual switches, heads up, switches can fail so take precautions.
Flying
Flying is what this model is about and at the field it does all the tricks to include . . . loops, rolls, stall turns, inverted flight, the lot!
Final thoughts
Allow me offer a few final thoughts. The right servo for you is a reflection of yourself, your goals, your dreams, and your budget. We put a better grade of servos in your hands. But nobody can make you buy them. This you decide for yourself.
Any questions? Feel free to reach out, we’re readily available;
- Telephone: 407-302-3361
- Email: info@promodeler.com
. . . maybe together we can suss out what’s best for you!
I’ll close with this, one thing’s certain, best is a race that’s never finished. Best right now? ProModeler, but far from David vs Goliath, we’re more akin to a flea on the elephant’s back in this battle with Hitec, Spektrum, an Futaba.
Means we need your help. Presuming you like our servos, then do us the favor of taking one to a club meeting. Pass it around. Maybe even pull out a 1.5mm Allen driver and open it up – there’s nothing to be afraid of. And please, show them to a pal.
But most of all, kindly grace us with a photo sharing your thoughts. What for? To put on the website, and within articles like this. Basically, for telling the next guy what you like about our servos.
We’re Jones-ing for photos like this one because your favor is priceless and can’t be bought. We know this. So do others.
Last thing
Have you enjoyed this? If you like reading and are interested in learning more, then maybe find time to review more articles like this;
- On the batteries John prefers using
- About pots vs Hall Effect sensors
- On selecting battery packs
- Pro tips for improving your ARF
- Amazon servo vs DS505s
- Why’s my pack got two JR-connectors?
- Rip Van Winkle, on returning to RC
- How to guide a rocket using servos
- Phoenix Models 70in Strega guide
- Advantages of pull-pull via pulley
- Bret Becker: Mr. Top Gun
- Will ProModeler servos work with NiCds?
- How to determine flight time for a 2S850 LiIon
- Hangar 9 60cc Pitts S-2B servos
- Fear of loss, or how to stack the odds in your favor!
- When LiFePO4 is mistakenly charged as LiIon
- Idle thoughts regarding chargers
. . . and hundreds more. Best part? They’re all free!