62in Kaos 60 guide

Background

In the late 1960s a fellow name of Joe Bridi designed a model powered by a .61-class engine. It spanned 59in and its purpose was to compete in AMA pattern. He named it the Kaos.

Honestly? I rather doubt he had a clue how popular it would become in a world populated by the likes of Phil Kraft and his Kwik Fli series. Ditto Ed Kazmirski and his famous Taurus.

It also led to Bridi Models, and a career in the sport. These days, pilots still do this, Andrew Jesky and AJ Models springs to mind.

Anyway, this photo is pretty much what an original Kaos looks like.

Note the elevators overlap the rudder and thus have cutouts and the nose of the model is set up for a spinner. These are the giveaways of an original.

And that it’s not an original is given away by the bit of wood covering the torque rod linkage (between the inboard end of the aileron and fuselage). Those, plus the fillets (which anyone can add, of course).

Whomever framed up and covered this example is a gifted builder.

Kaos – a simple model

Anyway, a Kaos is a simple model. Fixed gear, no spinner (just two curved sides simulating the look of a spinner), strip ailerons, plus a vertical fin reminiscent of a Mustang. That it was so simple meant it went together quickly. That it flew extremely well made it popular.

Build-wise, that a couple of doublers for the engine compartment sides forward of the firewall gave it the streamlined look without the added complication of fairing in a spinner, helped speed up the build. And this ‘look’ was part of the model’s charm.

Furthermore, in the spirit of simple, there are minimal formers, e.g. just the firewall, two nearly identical formers (one for before the wing (with dowel holes for the pair installed in the wing’s leading edge), and one immediately after the wing (but with a hole allowing the pushrods to clear), plus a simple third former.

Helping hold down the cost was it didn’t use plywood doublers for the sides (think Kwik Fli). And of course, it didn’t require a spinner. Holding down cost still further was the use of traditional maple engine mounts!

Allow me to note; if you elect to build from these plans and decide to ditch the hardwood mounts, then you need to adjust the angle of the firewall to compensate. Saying don’t just glue it in because Mr. Bridi designed the model with a fair bit of downthrust, so heads up!

Wing-wise, and in continuing with the simple theme, there are just ten ribs per wing panel. Structure includes upper and lower spars plus leading edge and trailing edge stock. These sanded to airfoil shape. And he went for an open sheeting design with cap strips for the outer 2/3 of the panel to keep it light.

Further simplifying things are strip ailerons. These actuated via torque tubes versus barn doors with bellcrank linkage (à la Phil Kraft Kwik Fli). So strip ailerons further speed up the build (with the added benefit of being a direct linkage leading to greater precision). Then finishing the wing were tips of solid balsa and fixed hardwood gear blocks.

And FYI, back in the day, a skilled builder working with Ambroid would frame up a pair of panels in an evening. Then sheet the top of both wing panels the next day (to include cap strips). Once dry, flip them over the third day and add the sheeting and cap strips. On the fourth day, sand leading edges to shape and glue on the wingtips, and epoxy the gear blocks in place. Finally, on the fifth evening, join the wing panels.

No clue what Ambroid is? It’s old fashioned nitrocellulose cement. I grew up using it and then switched to Titebond and CA, but nothing smells quite like it and a whiff brings back memories.

That said, aliphatic resins like titebond plus epoxy advanced the sport tremendously by speeding construction as compared to Ambroid. Then when CA in the form of Hot Stuff came to market, building took another leap forward.

And this just because a skilled builder could compress all five days of building in one evening to include sanding. To include using 15-minute epoxy for adding a strip of reinforcing fiberglass tape to the center section, but I digress

Anyway, the Kaos tail feathers include a solid 1/4in sheet vertical fin and rudder. The horizontal stab is quite lightweight being made of 1/16th sheeting with 1/4in diagonal square diagonal ribs plus solid 1/4in balsa elevators sanded to shape. The whole thing builds quickly. Add in the distinctive subrudder and visually Joe Bridi had created a looker.

All this means the fuselage, wing, and stabs go together so quickly you’ll have a model airplane in almost no time!

In fact, a Kaos was not just simple but flew great. Enough so, others had to have one and in 1970 Don Dewey published the above plans in RCM. And these Kaos plans were an immediate hit with the modeling public and the rest, as they say, is history!

Moreover, this model set the formula for ‘simple’ for decades to come. And thus, over the years many iterations followed. Some by Joe himself (Super Kaos), others by folks inspired by his work. These to include Kaos Jr. (40 size), Kaos 90, Ultimate Kaos, and Kaos 120.

Birdwalk – NOS

Heck, the mere fact a big outfit like Tower Hobbies is +50 years later offering a 60-size electric iteration with plug-in wings is proof (if you needed any) of how enduring Mr. Bridi’s iconic design has become.

However, well before this newest version, Tower Hobbies offered a Kaos 60 kit (actually a Super Kaos, note the faired in spinner). This one expressly promoted as a pattern trainer (and totally predating electric propulsion, so created with nitro engines in mind).

Thus, while the new Tower Hobbies 62in Kaos is primarily created with electric in mind, this original Kaos 60 model came well before electric propulsion became wildly popular. And note, this version is already 61.5in span and 707in² of area, so bigger.

Moreover, that version of the Kaos 60 model was sold by Tower Hobbies under their brand instead of Great Planes (who owned the Tower Hobbies brand, also). And they sold like hotcakes and in the thousands!

Means finding one is not exactly uncommon. There’s even term for this; NOS (New Old Stock). Said source may be a pal who has one in his stash, which he’ll never build. Alternative sources include an advert within RCG, RCU, or a club newsletter. Swap meets and estate sales are other obvious sources.

And they’re often advertised as NIB (New In Box). But be careful because they’re not all the same. For example, Direct Connection offered one, and below is a photo of one by Bluejay Airplane Kits.

When Bluejay sold theirs, it was set up as a tail dragger. Had a totally different looking vertical stab. More swept, and the horizontal stab was moved aft once again (as compared to a Super Kaos), and thus, hinged in the same plane as the rudder – like the original Kaos.

Heck, Bluejay even changed the size from 59in to 62-1/2in and subtly changed the name too, from Kaos to Killer Chaos (they even borrowed Mr. Bridi’s trademarked logo). Saying buyer beware because it may say Kaos (or Chaos), but this doesn’t make it so.

So if you want a Kaos kit instead of an ARF, there are alternative sources. What’s more, there are better than decent odds of scoring an NOS kit of the original Bridi model itself.

These are distinguished in having an orange label.

Anyway, by the time Joe Bridi was kitting it was the Super Kaos instead of the original Kaos with which he made his bones. Yes, it was still made for a .61 engine, and still supplied with maple gear blocks and 5/32in music wire for fixed gear (although I’m not sure I ever saw one fly without retracts) but by then he’d made iterative changes thus, making for a better flying model.

The most distinctive visual change (beyond the spinner being faired into the fuselage around the engine) was he moved the horizontal stab forward. This led to the stabs more closely resembling those of the P-51 Mustang because the aft end of the elevator surfaces ended right at the rudder hinge line.

More subtle, he ditched the forward hatch whilst at the same time deepening the forward fuselage slightly. This, to better accommodate the nose gear retract. Plane looks sort of the same, but different, more refined. Missing is the subrudder and the ailerons have a taper at the last four inches.

And it’s this plane, that is the basis of the Tower Hobbies 62in ARF.

Note the specs in the above photo of the label. Specifically eyeball the wing area at 644in² and the span listed at 58-1/2in and realize this was a smaller model than what Tower is peddling these days.

Lighter, too at 6-1/4lb with fixed gear. Speaking of which, when it came to retracts, back in the day this meant Spring Air or Rhom Air (both pneumatic) and for a certain number of builders, me for example, they may have used Multicon electric retracts from Kraft. Of course, these days electric retracts will more likely be JP or Electron.

Anyway, I still have all a set of three old school retracts (Spring Air, Rhom Air, and Multicon) within my assortment of stuff. This, because as a card carrying member of the pack rat club, I throw nothing away!

But for this model, today, I feel the Electron are probably best. Not the cheapest. And no, nothing in it for me to recommend them.

So why are these old models so light? Besides the obvious, e.g. due to being slightly smaller, there’s the one-piece wing the complication of the two-piece. The tube and stuff in the wing panels add weight. And significantly, I suspect the use of balsa versus light plywood, play a role. Add to it, I suspect they were choosier in their wood selection, also.

Remember, Mr. Bridi was a hands-on type of business owner and pattern mavens (then as now) were assholes about two things. The first being servo centering (hence, why I pony up for Nobel 1mc potentiometers instead of clones) and second, the model’s overall weight.

Anyway, let’s say you’re a purist. Like you don’t want a model based on the Super Kaos. You want an original Kaos, instead. Me? I’m not sure these were ever kitted. Fortunately, if you are willing to make the time required to build and cover same, there’s a kit available.

Join me on another brief birdwalk . . . kit cutters.

Birdwalk – Old School Model Works

Turns out if a kit is in your future – but – neither a NOS nor one of the off brand variations suits you (or is available), then all hope is not lost. This, because there are outfits dedicated to cutting laser kits of the original model.

An example is by OSMW and it’s very close to to the Bridi plans published in RCM. OSMW is short Old School Model Works and heads up, while I’m sharing info about their business, allow me to hasten to add, I have no relationship with them – none whatsoever.

Saying there’s nothing in it for me to refer you their way. Anyway, if you click this nifty logotype, it links to their site!

Anyway, this is what I’m talking you about building, Joe Bridi’s Kaos, an original sans spinner fairing. Complete with distinctive subrudder! And the price is a bargain. Especially if you consider the $57.95 the Super Kaos kit sold for in 1973 is $400 today according to my inflation calculator app. Just saying.

• Inflation calculator app on Google Play
• Inflation calculator app on the Apple store
• OSMW kit of the original Kaos model

If you look close you’ll see it’s faithful to the RCM plans. e.g. it also has the little bit of rounded vertical fin area below the horizontal stab, what I refer to as a subrudder. Saying this is a model, which once covered, will be indistinguishable from an original unless you hold the wing up to the light.

Only when held up to the light can you maybe discern the lightening of the wing ribs. But even this isn’t 100% as serious builders would have likely done rib lightening, also. This, because competitors take weight reduction seriously.

Moreover, as the caption notes, the OSMW iteration is not slavishly original but has a few nods toward modernity. Things like tabs for the formers (and note; there’s one extra former aft of the wing). This makes building it in your hands a doodle without fear of creating a banana.

And then there’s what’s missing. No maple engine mounts, so the firewall angle is adjusted, also. And especially important in my eye is how hard they’ve worked to reduce weight. Like note how the ribs have lightening holes. Me? I love in the bones photos!

Downsides versus the Tower Hobbies ARF? Traditional one-piece wing. There is, however, still the hatch, which makes battery swaps so easy. Anyway, if you’ve never built a balsa wood model airplane, then this is as good choice with which to lose your virginity as I can recommend.

Upsides? Plenty if you’re a traditionalist. Saying genuine SPA types (pattern competitors) will lust for its greatly reduced weight compared to the Tower Hobbies 62in Kaos. This, because when competing, AUW matters (AUW = all-up weight) a lot. And this model builds really, really LIGHT!

Light is especially important if you’re intent on using an old school .61 like an original Veco .61 (later K&B), SuperTigre blue head, Hirtenberger, Kraft, OS MAX gold head, Fox, etc. This because a modern incarnation OS MAX 65AX makes a lot more horsepower.

No clue what a Veco .61 was? Well, back when Mr. Bridi designed the Kaos this engine was the heat! Designed by Mr. Clarence Lee, from whom I subsequently purchased a Less Custom K&B .61 (he selected engines from the regular production batches and ‘breathed’ on them). It’s been the honor of my life to own one.

These loop charged engines, complete with a rotating butterfly exhaust baffle linked to the carburetor to keep the fire lit at idle. These designs soon fell by the wayside as more powerful Schnuerle boost port engine designs arrived.

Anyway, engines with boost port eliminated the fence on top of the piston and featured both shorter and later open timing, which better energize the fuel-air mixture. In short, they made a LOT more power and quickly killed off the old designs, think Webra Speed.

Anyway, my Veco .61 (above) was retired soon after purchase due largely to racket of the unmuffled design (high ear damage potential).

Circling back to the models, there’s something special about the traditional look of a Kaos vs Super Kaos. Like for some, me as an example, this may be important, but it depends. After all, this is 100% about pleasing you, not anybody else, take my meaning?

So maybe you noticed the mention of SPA types. SPA is an acronym for Senior Pattern Association, which leads us to yet brief birdwalk.

This time let’s briefly delve into what SPA is all about.

Birdwalk – SPA competition

The Senior Pattern Association is comprised of folks dedicated to the building, flying and competition of vintage pattern model aircraft.

Clicking the logo below takes you to where you sign up to join. Honestly? I wouldn’t be sharing this if not to encourage you to pony up the $20/year. We’re talking lunch money – but – a lot of benefit.

For example, once you join you’re going to embark on a rather fun journey of fellowship with like-mind modelers. A journey that will see you benefit via learning better building, setup, and flying skills.

Folks attending SPA events are basically flying and competing with pattern models from before the turnaround style came into force. Or as my old mentor once called them, whistle bombs. This due to their high speed straight and level performance (where 120mph is relatively common).

Talking about an era when props were available not just in 11×7 or 11×8 but in finer divisions, also. Like these competitors are so into fine tuning their models the prop manufactures responded with 1/4in divisions for pitch. Meant 11×7-1/4, 11×7-1/2, and 11×7-3/4 were available. These allowed the persnickety to really fine tune the prop to the airframe with tremendous precision.

Anyway, what most commonly springs to my mind when talking about SPA and 1970s vintage models like a Kaos are competitors like Rhett Miller’s Compensator, Don Lowe’s Phoenix 5, plus gorgeous aircraft like Ron Chidgey’s Tiger Tail, etc.

But they also include similar 1960s models like Phil Kraft’s Kwik Fli series and Ed Kazmirski’s Taurus and 1980s vintage, too.

And note, what distinguished all these models are the maneuvers. They’re from an era when AMA pattern was distinctly different from FAI maneuvers that came about in the mid 90s.

Back then (FAI included) were characterized by big air. E.g. occupying a lot of airspace. This from when staying within the ‘box’ was of zero concern. Talking about maneuvers characterized by the 1979 FAI schedule.

Note the Figure M . . . this was the maneuver which led Joe Bridi to move the stab forward when creating the Super Kaos.

Anyway, the concept of “staying within the box” in model airplane pattern flying, which refers to maintaining a defined volume during competition maneuvers, became a significant part of the sport during the mid-to-late 1990. The aircraft changed to fly in this style as downline airspeed buildup was a no-no.

Also meant the end of whistlebombs as pattern maneuvers evolved and competition rules were harmonized between the AMA and those of the Fédération Aéronautique Internationale (FAI) F3A category.

Continuing our birdwalk, let’s briefly touch on alternatives to kits.

Birdwalk – Outerzone plans

Turns out, no surprise, the plans to not just the Kaos but the models I mentioned above are all available online. The links to models I shared are to one of my favorite websites, Outerzone. They offer free plans for the model builder. For example . . .

• Outerzone – Kaos – free plans (in wingspans ranging from just 17in)

For the wood, I’d guide you to Bud Nosen Models, SIG, Midwest, Balsa USA, and others. E.g. the usual sources.

So you’ll note, above links Outerzone. I use links in articles frequently – and – for your convenience, they open within a new browser tab. Thus, clicking doesn’t mean losing your place within ‘this’ article. So click freely – later, go read up!

For those not in the know, Outerzone is a site in England hosting many, many plans online. They offer them for free, hence my troubling myself in pointing you to them. After all, the good stuff deserves to become more widely know. This is my effort at helping.

Anyway, these plans sometimes include photos, sometimes there are build articles, this link is to a free PDF of the original Kaos article in RCM. With this, Joe Bridi is effectively speaking from the grave as he explains what drove him to design the model!

But that’s not all as Outerzone also links to a CAD version of the Kaos plans, plus a vector drawing PDF (for if you’re not a CAD kind of guy). Vector meaning you can have the plans printed to any darned size you want and the lines won’t just get thicker and thicker as you enlarge them.

So earlier I mentioned RCM, let’s delve a bit further.

Birdwalk – RCM magazine

The plans for the Kaos were published by Don Dewey within the February 1972 issue of RCM magazine. RCM being the acronym for the long defunct Radio Control Modeler magazine, which I once eagerly awaited reaching the news stand at my local hobby shop.

Back then, in the bloom of my youth, it should come as no surprise a 14 y/o bought the magazine off the newsstand. This, because I was working for pocket money by building models for others, delivering the Birmingham News in the mornings, mowing yards, raking leaves, etc. Basically, I didn’t feel I could afford a subscription.

So to say I cut my teeth reading and re-reading each issue over and over would NOT be an exaggeration. Anyway, when Mr. Dewey passed, RCM soldiered on a few years but without the founder, the publication flailed and ultimately, foundered and disappeared. Except the plans, those largely remain . . . thanks to Outerzone.

So how popular is the Kaos design? Enough so, that I, who began flying just a couple years after the original article was published have built a handful – call it at least 5, maybe 6. Possibly seven. One of the original, plus iterations.

Like there was the original Kaos build, two of its successor (aka Super Kaos with a spinner faired into the fuselage, both with retracts). Also a couple of Kaos Jr. (40-size version of the Super Kaos). One with retracts, the second a better flying version (lighter) with fixed gear.

Saying I may have built one or two for guys, which I’ve forgotten in memory (this because I’ve built a ‘lot’ of models both in high school and college to earn pocket money).

In fact, I faired in the spinner on my very first Kaos build. This, because adding a 1/16in plywood ring and a bit of balsa wood to sand it to a low drag shape was a no brainer.

While I was at it, I ditched the maple motor mounts and opted for a Kraft engine glass filled polymer mount. Point being, I know the Kaos really, really well.

Anyway, the aircraft is so well designed, flying it is an experience as honest as the day is long. That it remains popular approaching 60 years later is why we have this guide. A guide, which came about when a fellow reached out to say he’d bought a Kaos 60 from mail order dealer Tower Hobbies and wanted a servo recommendation.

So lets talk about servos. Yes, at last! We’re done birdwalking and getting down to the meat of this caseSTUDY article.

Servo recommendation

So my customer wondered what I’d recommend servo-wise, and for my part, I was intrigued by his question. This, because until his call, I’d only thought of Tower Hobbies and Kaos in terms of a traditional model of the Super Kaos 60, a balsa kit made for .61 engines.

That, and as the very handsome 40-size version of the Kaos 40, once offered as an ARF (but with one-piece wing and no provisions for electric propulsion, like for readily exchanging batteries).

So that they now offered a 60-class ARF with two-piece wing and oriented toward electric propulsion – and – that it sported a large-ish 63in span, was news to me. Lynn says I live under a rock, so here’s proof because the model has been out for many, many years and I only recently twigged to its existence.

Anyway, cutting to the chase, we offer servos in various sizes. These being (in decreasing size-order), standard, mini, micro, and sub-micro (these last being what’s commonly referred to as 9g servos although ours aren’t). And interestingly, we offer all four sizes in a range of 100oz-in, which as it happens is enough for this model.

Saying any of four ~100-oz-in class ProModeler servos provide enough performance for a Tower Hobbies Kaos. But just because you can fit them doesn’t mean you should fit them. There’s a difference.

So while my preference are either standard (largest and requiring slight mount modification) or the mini (what the mounts are sized for), an experienced modeler can readily adapt the Kaos model to either larger – or – smaller servos. Saying you’re a big boy and it’s your money, select the ones that best suit you!

Or put another way, horse for courses and I’m going to give you the pros and cons of regarding our alternatives. First, let me be clear, I’d rather guide you toward the larger servos. Why? This, simply due to the fact the larger the gears, the more durable the servo.

Anyway, these four servos are referred to internally as the Century series. Why? Simple, because all four output in the range of 100oz-in.

Standard-class DS90DLHV

The physically largest of the group is the DS90DLHV. It’s one of five in a series ranging from 90-360oz-in. Anyway, if money is tight, then the DL90DLHV is the most economical alternative for the Kaos within the ProModeler lineup.

However, being standard size (40x20mm class) means they’re 4mm longer and wider than what’s called for (a mini class, or 36x16mm). Since 3mm is about an 1/8th of an inch, this means a little bit of modding is in order when fitting standard class servos. not much, not hard, but heads up.

So what do you get for your money? Well, for example, if you ever uncover a DS90DLHV gear train, then this is what you’ll see.

You’ll be getting all stainless steel gears, 13 seals and o-rings, an alloy center case CNC machined of 6061-T6 aircraft aluminum, plus an added benefit that your servos meet eight MIL-STDS.

Mini-class DS110CLHV

Next down size-wise are the mini size class servos. These are exemplified by our DS110CLHV. And FYI, while we offer minis ranging from 110-405oz-in, it’s my opinion the DS110CLHV is all you need for this model. Reasons have to do with the modest sized control surfaces. Like if it were a 3D model where elevators were 60% of total horizon stab area, then sure, opt for more powerful servos!

Also, the DS110 are incredibly quick, which makes them ideal when using a gyro. Gyros? Yup, these days many folks fly models incorporating Spektrum’s AS3X gyro technology in the receiver. And regardless of your opinion about using them, gyros aren’t going away.

Another gyro route is adding a Flex Innovations Aura8 (or any of many other tiny inexpensive gyros). Sure, maybe illegal for competition – but – if you’re not competing, then who cares? After all, the beauty of gyros is they make mid-size models like the Kaos 60 fly like 120cc model aircraft!

And gyros are especially nice when flying in turbulent breezes. Just saying, being faster than a goose dumps a load before taking flight makes the DS110CLHV the perfect servo if you have gyros in the back of your mind.

Also, while the DS90DLHV will require a bit of work to use in this model because they’re bigger than the standard class servos called for in the kit built Kaos Tower Hobbies once offered), the mini-class DS110CLHV will basically drop right into the Tower Hobbies 62in Kaos.

This, because the Kaos has mounts sized for mini-class servos. But as you can see, opening the mounts a tad to fit larger servos isn’t rocket surgery because they give you plenty of beef to work with!

And to be frank, there’s a lot to like about ProModeler mini-class servos. For example, just like with the larger DS90DLHV, once again you get the stainless steel gear train, plus o-rings and seals to protect against environmental intrusion. And eight MIL-STDS.

An example being, when you pop off the cover of the electronics section, you’ll see a generous application of monkey snot (aka potting compound). We refer to it as monkey snot because the stuff is sticky and won’t come off easily (and because of the stench). Stench because saying it stinks is understating things.

Basically, monkey snot is what stands between you and engine vibration. Applied in a liquid state, once it’s flows between components, it sets up and solidifies, thus encasing the delicate electronic bits and helping by absorb impact, shock, and vibration.

So if you ask yourself, What’s in it for me? Straight up, it’s better resistance to shock and vibration. Like infinitely better than what you get with hobby grade servos.

However, it’s when you look closely at the rest of the servo and realize instead of plastic or a smooth alloy case, this alloy center case is CNC machined with cooling fins that you realize how special this servo actually is. Especially when you note the motor is a tight fit to the aluminum. This, to efficiently transfer heat from the motor’s steel can to the alloy case, which means the center case is doing double duty because it not only anchors the transmission but also acts as a heat sink!

So both cooling fins ‘and’ pressing the motor into direct contact with the case combine to help your servos better shed head. And this is important when they’re working hard. So the question then becomes, do other servos you’ve considered for your Kaos give you this?

Micro-class DS100DLHV

Another possibility includes our micro servos. When it comes to my overall recommendation, we’re also going to include our micro servos, of which we offer two because they work very well, also.

So our DS100DLHV is a great budget choice (and better alternative over either DS90DLHV or DS110CLHV because they’re lighter.

However, you’ll have to modify the servo mounts to fit a smaller size servo than what they had in mind. Of course, if modding the mount makes you lose sleep, then get the DS110.

Also, by way of heads up, if our prices don’t send you screaming into the arms of low end Asian imports, then if I were equipping this Kaos for my personal use, I’d opt for the upscale version of the micro in our lineup. This being the DS150CLHV.

And FWIW, I’d equip the micro servos with PDRS15-25T arms because then I could use higher precision M2 ball link hardware instead of kwik links. Just saying.

Honestly? The DS150CLHV would be my first choice amongst all our servos for a Tower Hobbies Kaos 60 build for my use. Simply put, in my opinion, this is the best servo we offer for this model.

Sub-micro class DS105CLHV

To the question could I make the DS105CLHV submicro servos work? Why yes, absolutely, of this there’s no question. But I wouldn’t in the Tower Hobbies 62in Kaos. Why not?

Reason for this is more to do with the heavier weight of the build and the minuscule size of the gear train. This, more than anything else. Basically, smaller gears are more delicate.

That said, put plenty of guys use them in SPA models. But these are modelers for whom low weight is extremely important. So you’re not going to find two-piece wings and lightply fuselages, strictly contest grade balsa and a focus on the best wood possible.

Circling back around to why not. Like all four of the servos in the Century series, which are rated in the ball park of 100oz-in, remember that’s their rated output.

What I’m talking about is a concern related to input. Input being defined with reference to accidents and crashes. Like when someone in the pits bumps the stab with their foot. Or as the model encounters ‘life’ (bumping a stab into a door frame or the edge of the trunk opening).

Talking about the things that just happen despite our best efforts at living a clean life, e.g. being perfect. So it’s the unplanned for – but predictable – events, which may break the teeny tiny gears of a sub-micro I am warning you of. No, not saying you can’t successfully use them but saying maybe you shouldn’t.

This is because we’re talking about 21g servos, which when compared to +60g servos get competitors excited for the weight savings – but – unless you’re a competitor, then my advice being you’d be wise to avoid our DS105CLHV sub-micro servos for ‘this’ particular model.

Especially if you plan to use an engine. With an engine, the the smaller the gears the more engine vibration comes into play as a wear issue. And this is true for any servo on the planet whether it’s ProModeler, Hitec, or Savox because we’re talking physics!

Put another way, when it comes to strength of materials, bigger is always better. Am I trying to talk myself out of a sale? Nope! Just want you to make an informed decision.

So now let’s talk about the build itself. As in pretty much everything in life, there are few solo efforts. This caseSTUDY is no exception and I have a lot of folks to thank for their help.

Acknowledgments

I gratefully acknowledge help in the form of photos and advice from a cadre of highly experience modelers. They freely shared tips and tricks and without them, this article would be nearly as useful.

So before delving into landing gear configurations, engines and motors, plus flying, let me thank the following (and in no particular order). Basically, these are the guys who stepped up when I asked (and for the most part, with no clue who I was, or for what purpose). They just took it as an article of faith when I asked for help, to a man they said yes. We owe them a vote of thanks.

The end result speaks for itself as this caseSTUDY article is more complete and useful. Now, because these fellow unselfishly shared their knowledge everybody going forward who builds one of these Tower Hobbies 62in Kaos models will have a better idea of what to expect and what to watch out for;

• Brad Frere
• Larry Tener
• Dave Swanson
• Todd Duggan
• Eric Schmidt
• Mike McDougall
• Jim Johns
• John Wold
• Robert Fish
• Wayne Cook

. . . and note, the above photo by David Swanson, is of the same model which graces our article, what we refer to as the hero image. So it was a struggle for me to select between the aft and fore view because both are so handsome.

Anyway, with no further ado, let’s touch on mods to improve the model whilst building before embarking on flying it.

We’ll begin with the landing gear, both main and nose gear repairs, a switch to conventional landing gear with wheel pants, and then we’ll touch lightly on what’s involved in installing retracts.

Landing gear – repair, conventional, retracts

The landing gear is a source of much complaint. We’re going to touch on three different approaches. One is repairing what for many were hardwood main gear blocks held with insufficient glue.

An alternative approach is to replace the landing gear altogether with conventional gear, in essence making a taildragger of the Kaos.

And the final approach is the classic for the Kaos, retracts!

Repair

Main gear blocks with insufficient glue are a fairly common complaint. Honestly? Nothing spoils a day like making a decent landing only to have the gear give way. And it’s not than the wire is shit quality because it’s plenty heavy duty. Maybe too much so.

Turns out the source of trouble is twofold. The first being the plastic blocks for the nose gear crack easily. And second, the main gear’s hardwood blocks simply lack enough adhesive and may rip out.

Are these issues to do with a bad batch, or more systemic? Dunno but enough folks complain, if it were me about to build on, it’s worth checking and fixing before ever going to the field.

These photos, generously shared by Todd Duggan, show how a highly experienced modeler addressed the results of the landing gear being ripped out. They succinctly tell a compelling the story.

We were fortunate this expert builder shared these photos because many, many folks have discovered the main gear blocks rip out with distressing ease. And this is still true as of the time of this writing because when I mentioned it to the customer who started me on the path for this article, he subsequently reached out and told me his broke with hand testing.

That, and the nose gear mount material seems to be too brittle. So by showing us what’s involved, the fellow who shared these photos of what was a dog’s breakfast, has made it easy for the next guy.

If it were me, immediately after purchase, I’d do what my customer did and closely inspect the main gear blocks in the wing panels. He said it looked fine but after installing the main gear wire and wheel, he took a shot at ripping the gear out with his bare hands, and it broke loose. Said he was surprised as he didn’t really put his back into it, or otherwise play gorilla. Honestly? A modest effort shouldn’t make it whimper.

Anyway, like pull-testing hinges, better it comes out in the workshop than later at the field. Especially since a few minutes work reaching in to add more epoxy probably makes it right without first trying to rip it out (so test after you add epoxy). But that’s just me.

Conventional gear conversion

Another approach involves ditching the tricycle landing gear altogether in favor of conventional gear. Several folks have done this which has the benefit of simplifying the model, and Brad Frare kindly shared these photos.

So what’s involved? Not much, really. Basically you’ll be adding a small rectangle of 1/4in plywood to the inside of the fuselage (inside, full fuselage width by about 2-1/2in wide).

Afterward, reinforcing the plywood with two short pieces of stock (where it mates to the fuselage sides). This increases the glued surface area of the joint.

And the observant will note while he was at it, Brad added an additional former. This one is a bit aft. Just forward of the wing tube.

The purpose being to support the fuel tank when moved further aft in his quest to minimize CG shift as the fuel level goes down. Neat!

And lastly, if you’re feeling fancy, maybe a set of wheel pants, too. Match the trim while you’re at it and just like that, Bob’s your uncle!

Head on, the model now presents a purposeful look. And with the four stroke sound stirring the soul, the model is now customized and different from any others which may appear at the field.

Along with the tail wheel the stance changes the look of the model.

This very accomplished modeler is detail oriented. Proof being he took the time and made the effort to match the color scheme with the wheel pants. End result is like it had been born this way!

Next, let’s see what retracts involve.

Retracts – the classic look

So fitting the model up with retracts is remarkably easy. And if you’re repairing the main gear anyway, then maybe just knocking up a a set of retract mounts will be a productive afternoon project. We’re fortunate Wayne Cook generously shared photos and shows us an expert modeler’s approach to fitting old-school Spring Air retracts using a few scraps of aircraft ply.

The key piece is the U-shape made of 1/4in plywood. Notch the ribs enough to accept this. The other bits and bobs are supports. Dry fit until you’re reasonably happy then epoxy in place.

Remember, these will be a little bit different depending on the brand of landing gear – but – they all come with mounting templates. So just eyeball the pertinent dimensions and go to town.

One thing I see guys cock up is they install blind nuts and 4-40 or 6-32 landing gear bolts. Like they’re anchoring the Titanic. My advice, don’t do this. Instead, mount the main gear units with #2 sheet metal screws.

Wont they rip out? Yes, that’s the point. And once they rip out, guess what? Drill new holes and fit 3/16in dowel and then drill for new screws. Rip out again? Rinse, repeat. The beauty of this system is the wing itself isn’t damaged, just your pride. And believe me, it tales a lot to rip out the #2 screw like we supply with servos. They won’t just fall out on arrival, it’ll take a decent impact.

Another approach substitutes nylon bolts for steel machine thread bolt – but – I find these to be a pain in the ass to remove (heat a small flat tip screw driver, press into stub thus forming a slot, then extract).

Anyway, pick your poison. Next, let’s look at engine installations as we have alternatives to include 2-stroke upright, sideways, muffler, or with tuned pipe, plus small gassers and 4-stroke engines.

Motors, ESC, and BEC

So the decision to opt for electric is almost baked in these days. A lot of fields have noise issues, while some folks don’t want to deal with engines. I get it. Then if quiet flight motivate you, to each their own!

Motors

E-flite

The typical setup, and what Horizon guide you toward, is their inexpensive E-Flite 60 motor. This 470KV motor (1800W) relies on a 6S pack and is splendid for purpose.

RimFire (now marketed as the Spektrum Avian)

There’s also the popular line up of RimFire motors, this photo has been very kindly shared with us by über experience model pilot, Mike McDougall (a retired EE who has been flying RC since vacuum tubes and rubber band escapements).

This RimFire 80/Castle Creations Talon 90 setup is good for 13-14in diameter props – with – decent ground clearance.

And FWIW, more than one fellow shared how well the RimFire 80 worked with this model. For example, another fellow who used a HobbyWing 100A ESC shared he keeps notes on all his planes and flew his Kaos with props ranging from 13×8 to 14×12, with the 13×10 being his favorite.

BadAss (I don’t receive a nickle for sharing this)

But there are alternatives motor-wise. I won’t get too deep into the weeds because the info ages. So here’s what I did. First, I touched bases with Lucien Miller of BadAss. This, because of the depth of his knowledge of all things electric. His site is Inno8tive Designs and he’ll be happy to guide you to what he feels is best in his lineup.

Update: Lucien jumped on the opportunity to share information with you and sent the following:

When we introduced the BA-3530 size motors back in 2018, we only had 4 Kv values available, and the two that were the most favored for SPA Pattern were the BA-3530-570Kv and the BA-3530-700 Kv, both running on a 6-cell LiPo battery.  The 570Kv version performed like a .90 4-Stroke engine or a long-stroke .61 2-stroke engine on a tuned pipe.  This motor favored large props like a 12×10 or 13×8, and spins up at a little over 10,000 RPM.  This is a favorite for the pilots favoring the later model pattern planes that used larger props and had longer landing gear.

For the earlier model pattern planes, that had shorter landing gear and required smaller props, the BA-3530-700 motor was favored.  This motor runs like a high speed .61 2-stroke engine on a tuned pipe, and will spin an 11×7 prop at around 13,200 RPM at full throttle.

After receiving a lot of requests for a motor that was in between these two, which more favored 12-inch props, we introduced the BA-3530-630Kv motor.  Pre-production samples of this motor were set out to several SPA pilots, and every one of them said that this motor really hit the sweet spot, and worked exceedingly well in planes such as the Bootlegger, Kaos, Dirty Birdy and other planes of that type.  With a 12×6 prop, the BA-3520-630 motor will spin at around 12,300 RPM and make over 10 pounds of thrust running on a 6-cell battery.  With an 11×8.5 prop, it will push a .60 size pattern ship over 100 MPH with amazing authority.

As with all of our BadAss motors, we provide an extensive Propeller Data Chart for each of the BA-3530 motors that contains over 100 different combinations of props and battery voltage, so you know the exact performance that you will get for the planes.

Links these motors and their associated Propeller Data Charts

• BA-3530-570 Motor:  https://innov8tivedesigns.com/badass-3530-570kv-brushless-motor.html
• BA-3530-570 Data Chart:  https://innov8tivedesigns.com/pub/propcharts/BA3530-570-Specs.htm
• BA-3530-630 Motor:  https://innov8tivedesigns.com/badass-3530-630kv-brushless-motor.html
• BA-3530-630 Data Chart:  https://innov8tivedesigns.com/pub/propcharts/BA3530-630-Specs.htm
• BA-3530-700 Motor:  https://innov8tivedesigns.com/badass-3530-700kv-brushless-motor.html
• BA-3530-700 Data Chart:  https://innov8tivedesigns.com/pub/propcharts/BA3530-700-Specs.htm

To compliment the BadAss Motors, we have a full line of BadAss Speed Controller in our Rebel and Renegade series.  These ESC’s can be found at this link on our site.  https://innov8tivedesigns.com/products/speedcontrollersandbecs/badass-speed-controllers.html

The BadAss LiPo Batteries are premium quality packs that are designed to withstand the rigors of competition flying.  Our full line of BadAss Batteries can be found at this link.  https://innov8tivedesigns.com/products/batteriescharging/badass-lipos.html

Finally, if you want one of the best looking props available, that proudly bears the BadAss name, you can find our full line of BadAss props in sizes from a 10×4 up to a 30×12 at the following link.  These props are CNC machined from Romanian Beechwood and are finished with a UV cured gloss black finish with white painted tips for good visibility. https://innov8tivedesigns.com/products/propellers/badass-wood-props.html

Aeroplaying

I also picked Jim Kitt’s brain. Honestly, Jim’s forgotten more than I know about propulsion motors and props generously shares his knowledge. Moreover, he stays on a top of a propulsion motor thread on RCG which is for Extreme Flight models and which is +2000 pages. Like no way you catch up on all of that thread!

However, Jim generously shared a few thoughts regarding one of Lucien’s 830KV motors as well as a 660KV motor. He found the former quite suitable for the Kaos stating . . .

They are claiming:
830 no-load RPM/v
Maximum Continuous Current 110 Amps
Max Continuous Power (6-cell Li-Po) 2440 Watts

They are rounding up, which is totally acceptable, and this means they are claiming 2440W at 22.5v at a straight 80% KvE, which we’ve always used here for this size motor and prop.

So 22.5v * 830Kv * 0.80 KvE = 14,940 RPM
With a 12×7, this would mean 0.1305 kg-m
0.1305 * 830Kv = 108.3A and rounded up is 110A
108.3A * 22.5v = 2438W and rounded up is 2440W

This also happens to be 14.3 lbs of thrust with a 114-119 mph estimated airspeed. And this is about as far as we’d like to take the tip speed (Mach 0.69) since more RPM will begin to reduce efficiency if it hasn’t started already.

And with regard to the 660KV motor, says the following . . .

14×7 on the 660Kv – bigger prop to lower RPM – is that it illustrates how going in this direction increases the Amps per pound-force efficiency.

A 14×7 on a 660Kv motor to the same 80% KvE means 11,880 RPM. This is 0.153 kg-m and 100.9A to 14.5 lbs of static thrust with a 91-95 mph estimated airspeed.

So we’re getting the same thrust while drawing 10 fewer Amps with less but acceptable airspeed. This is a perfect example for understanding the options, relative to thrust and speed performance, by making a strategic choice.

If thrust was the main variable as long as the speed was acceptable, then the Amps per static pound-force for the 14×7 is 8.3% more efficient with the bigger prop to lower RPM.

Anyway, Jim’s a walking encyclopedia on everything motor/prop related and I’m proud to count him amongst my friends. If you have even a passing interest in flight powered by electrons in urge you to follow the power thread.

Next, moving on to ESCs.

ESC – the throttle for motors

ESC-wise, something in the 100A range is likely going to suit. So if you have a 90A Talon in a drawer, or a 115A Jeti, then use it. Or buy something new. Everybody has a dog in this hunt, us included with an inexpensive 120A good to 6S.

BEC – bad juju

So BECs are popular with itty-bitty model airplanes. However, the BEC (acronym for Battery Eliminator Circuit) is a singularly bad idea in this class of model, in my opinion.

Thus, I’ll guide you away (urge you in fact) way from relying on one of these for any and every ESC you can buy for the Tower Hobbies 62in Kaos, which includes a BEC circuit. To include our own as well.

Pay attention to the words of this next fellow. Take heed.

Why am I dead set against depending on a BEC circuit off the ESC? Remember the kindergarten tale regarding the ever cheerful chick named Peep and carrying all her eggs in one basket? The story’s purpose was teaching us – as children – how when something goes wrong and you’re all in one one solution it may mean losing everything.

Turns out this remains a useful lesson to bear in mind with our models, too. This next photo, kindly shared by Alex Hewson (the fellow flying above) shows the aftermath of his ESC going poof, which also took out the BEC circuit.

Having all his eggs in one basket led our mate in New Zealand to become a spectator as he helplessly watched his model bury itself.

Major point being, had Alex been using a dedicated pack, when the ESC went tango uniform it merely would have meant a dead stick landing instead of a crash. Reason I have this photo?

Well, Alex is a big hearted fellow who shared it with me because I’d tried to get him to use a dedicated pack. For his part he’d been so closely focused on AUW he’d lost sight of the big picture, so he chose not to.

As for the photo, it serves to show not only a big heart but big time character for reaching out to say, ‘you were right’ when he ordered a B2S850 pack for his replacement (the model in the photo). He said, I thought you might get a kick out of this photo, feel free to use it to help others.

Speaking of the model in the photo, that’s Extreme Flight’s lovely 69in Turbo Raven. It’s a 6S model as well and if you’re curious about it, we have a caseSTUDY available to help guide you.

So next we’re going to briefly touch on two types of batteries for your Tower Hobbies Kaos. These being the big heavy propulsion battery and the smaller avionics battery.

Battery packs – propulsion and avionics

Obviously, if you’re opting for an engine then skip down to the latter!

Propulsion packs

When it comes to the 6S propulsion pack batteries, these may range in capacity from relative lightweights like a 4000mAh to a heavyweight 5200, pick ’em. 4400mAh seems like a reasonable compromise.

The criteria is flight time to the 20% discharge point. Learn more:

• The care and feeding of LiPo packs

As a rule, if you’re sport flying, then stuff the largest one you can fit to get the most flight time. However, if you’re competing, then you only want enough capacity to complete the schedule of maneuvers and land. This because you don’t want to carry a single unnecessary gram of mass. Duh!

Whose propulsion batteries do I like? I like Danny Sullivan’s packs (SMC Racing) because I find them to be a compelling value. That said, Lucien Miller is making a strong push with his BadAss LiPos.

Which is best for you? Dunno, your call. Both of these guys know a ton about batteries, are aware of each other and thus, are engaged in a dogfight for market dominance.

Of course, neither actually makes the pouch-type LiPo cells but instead, use their deep knowledge when speccing and buying. What’s tricky (and the fundamental reason we exited the LiPo business) is that Chinese cell vendors lie.

To be frank, they seem to lie even when they don’t even have to. So because I grew frustrated with lies about everything, like even if they made the cells or bought them and assembled, instead, I threw in the towel. Especially as these folks switch cell-making technology at the drop of a hat, and worst of all, make claims that are difficult to verify. In particular to C-ratings. No offense to those willing to deal with that nonsense but I’m an engineer and as a numbers guy, I expect the numbers to be straight up truth without marketing’s influence.

Anyway, it’s my opinion what this means for them (Danny and Lucien but also everybody else in the business) is this; the packs they bought this time won’t necessarily be the exact same the next time. Me? I’m a simple guy and became fed up with what I viewed as endemic lying, so I threw in the towel and refocused on our servo business where I get what I pay for.

For example, when a motor vendor gives me spec, I can measure. E.g. the KV and Io, plus I can weigh it, input current and measure RPM, etc. I can also cut them open and verify poles and construction, wire diameter, winds, etc. Packs rated at some amount of current flow based on their capacity? This, not so much.

So proceed with care is my best advice before reaching for your wallet. Or go with one of the two vendors I mentioned above. They’re both good guys trying their best.

C-rating – liars, bad liars, damned liars

Me? I’m still rather less than trusting about pack performance claims. Reason for this is simple. It’s because C-rating are use to make sales. Fortunately, there’s a fellow who has made it his life mission to test and rank propulsion batteries.

My advice? Get familiar with the first page of this battery thread (which has grown to over 1000 pages). Joe Giamona stays on top of it, meaning he keeps it updated. And he reports the real world truth.

• RC Groups Battery Test Comparisons

Bottom line? This guy’s data is of such integrity I trust it implicitly.

Avionics packs

When it comes to the avionics battery, the 2S pack connected to the receiver to power it and the servos, with these I do have a dog in the hunt. That said, if you’re unaware, every pack whose brand I can name are assembled using cells made by CATL in China, us included.

What this means for you is the brand on the heat shrink doesn’t actually matter. Like these people make billions of individual cells in a year and all told, every single battery pack used in the model airplane world sum up to a rounding error. Not enough models and thus, we just don’t matter.

What does matter? In my opinion only, a) the type of connections made to the outside world, and b) the number of them. So what kind and how many leads. Period.

As for the bullshit about we individually test cells so our packs are better, it’s just that, in my opinion, BULL. Why? Simple, it’s because these things are commodities (means there’s virtually no money in them). The obvious corollary of there being no real money in them is this; who is going to detail a tech costing $25/hour to test individual cells? Honestly? This claim doesn’t even pass the sniff test, but whatever, if you choose to believe in pixie dust and unicorn farts, then KYO.

For our part, we sell hundreds of packs (and we’re merely a bit player in the business). Crude of me to use such coarse language? Yes, but it’s purposeful. Reason is I want to get your attention.

What I am saying is please engage a few brain cells and devote them to critical thinking when reading advertising copy. Nobody on the face of the planet spends an added $5 labor testing a $25 battery, but believe what you will.

Anyway, for a Kaos, our B2S850 is great if you’re a weight conscious competitor intent on shaving grams. Good for maybe three flights in a pattern plane without pushing things. Why LiIon instead of LiPo? Simple, I trust metal shell cells more than plastic bags. LiPo propulsion packs go in and out all the time for charging but the avionics pack is usually buried somewhere for balance purposes and isn’t removed. yet a snap roll could let it shift against a former, makes a crease, presto, instant potential hotspot and source of ignition. So metal shell cells if you get them form us. But you do you.

And while we’re on a theme, I’m less than trusting of LiFe packs (like LiPos they’re built in a plastic pouch). Instead I only put my trust in metal encased cells with LiFePO4 chemistry (slightly different from LiFe to allow them to be rolled instead of laying flat).

Me? Instead of the 850mAh I’d probably use the our B2S1800 pack in a Kaos because I prefer the ease of living with A123 cell technology.

Don’t know diddly about battery chemistry? Read up here:

• On the batteries John prefers using

Leads

One thing that jumps out about our receiver packs versus competitors is we give you two JR-type leads instead of one (technically these are all DuPont connectors regardless of whose proprietary bit of black plastic gets used, e.g. JR, Futaba, et al). And we also give you an XT30. This is an easier place to make connections for charging/discharging. And both with high strand leads with silicone jackets, e.g the good stuff.

Anyway, two leads for the former (20AWG wire) and a 16AWG lead for the 30A connector. Looks like this.

So why two DuPont connectors? In a nutshell, the primary reason for two in a low current drain model like your Kaos (meaning just a few low torque servos) is so you may use two switches.

After all, odds of both switches failing on the same flight are astronomical. And FYI, switches are the least reliable component in a model airplane. Followed by servos, receivers, then batteries.

Batteries are the most reliable? Yes, ions are going to flow between cathode and anode as surely as an anvil will fall of a cliff. Physics.

Modelers too stupid to confirm battery level before flight? That’s not the battery’s fault. Me? I plug in a tester and measure voltage before every flight. No exceptions. When I see 7.4 on a LiIon or 6.6V on a LiFePO4, I stop flying and recharge. Simple.

And of secondary importance with a smallish model (again, because of the modest number of servos and low-ish current draw) is this; because making two connections between the pack and the receiver lets the servos draw as much as 7A without heat build up vs 3.5A with one connector this is better.

Having two is ALWAYS better in my opinion but you do you. And if you already have a pack, then you can slit the heat shrink, solder on another lead with connector, replace the heat shrink and Bob’s your uncle.

You’re welcome to your opinion but the facts are the facts. These connectors are rated at 3.5A continuous. Look, we’re in the servo business, other stuff like batteries, extensions, servo arms, etc. are a convenience for the customer. So servos pay the bills. And if we’re going to trouble ourselves to source batteries, extensions, etc. then we’re not going for cheap shit, but for the good stuff. And note, others will build your packs with multiple leads, you just need to be savvy enough to ask. Saying we don’t care where you get your packs, just be smart enough to understand why two leads are better for you.

Learn more here:

Why’s my pack got two JR-connectors?

So this sums up the thinking on batteries for both the propulsion and the avionics (control electronics, e.g. receiver and servos). Next, let’s delve into engines.

Engines – 2-stroke, 4-stroke

Interestingly, how you install an engine doesn’t really matter. But back in the day, the classic installation had the cylinder head upright. So we’ll lead off with a photo showing off this practical approach.

Upright cylinder head

So the benefits of an upright cylinder head installation are the exhaust largely misses the model. Yes, a little bit may get on the vertical stab and rudder but it’s not too bad.

Yes, it also spoils the look a little bit according to some – but – maybe because I’m just an old fuddy duddy, but I rather appreciate the classic upright look.

And what I especially appreciate is the low maintenance approach to clean up! This is an example showcasing an OS MAX 65AX.

Another benefit is it places the needle valve spray bar assembly a bit higher than the centerline of the fuel take. This is better for most engine operations. Note the extended needle valve. Some don’t like it but I do and this highly experience modeler has chosen to fit one. The purpose, of course, is to help keep hands further from the prop.

Folks, prop injuries are no joke. Don’t believe me? Then let this article be a cautionary tale.

• Regarding props – heads up!

Side-mount 2-stroke – muffler

Side mounting an engine is a nice way to maintain the unbroken profile of the model airplane’s fuselage. Yes, you see the engine flying left to right, but on the right-to-left pass, the profile is unblemished by the engine and exhaust and looks almost jet-like.

Downside of side mounting is exhaust goo can be an issue. But it really depends on the exhaust installation, e.g. muffler, or tuned pipe. Jon Wold of Norway kindly shared photos of his expertly fitted OS MAX 65AX and a superbly trimmed cowl.

Only thing is, with the OS MAX 65AX and a muffler, you’ll need the OS MAX Extension Adapter 744b.E-4010 65AX (also suitable for 75AX/95AX). This, so the muffler will clear the cowl as otherwise you have to hog away a large part of the cowl . . . heads up!

Side-mount 2-stroke – tuned pipe

So while a muffler installation is straightforward, a piped engine is a bit more involved. Depending on the engine, shopping for a header can be an adventure.

For example, this photo was shared by Eric Schmidt who chose to side mount a Rossi 90 engine. Honestly, this much horsepower creates a genuine 150mph experience. One that defines the term whistle bomb.

And flying this model, especially equipped with so much horsepower is a guaranteed giggle maker. After all, that’s the point, right? Fun!

So this exhaust stream will pretty much only get on the horizontal stab. Clean up isn’t too onerous. And the fun makes it totally worth it.

Side-mount 2-stroke – tuned pipe, part 2

So an alternative side mounted engine with tuned pipe sees the modeler using an offset pip and routing the pipe down the belly. As it happens, this is a pain in the ass with a one-piece wing but duck soup with a two-piece wing as nothing needs disassembly.

We’re fortunate to have this next photo sequence by Robert Fish, who expertly trimmed the cowl when fitting the side-exhaust engine so that no part of the engine assembly touched. Robert also is a man after my own heart for having down the new engine break in on a test stand instead of the model.

So if this were a traditional model with a one-piece wing then each time the wing comes off the pipe does also. Get old, believe me. Been there, done that, have the t-shirt.

But with a two piece wing setup, once you get the header/pipe length set up for the powerband you’re seeking, you’re done, it’s set and you don’t screw with it again unless you change something (e.g. fuel, glow plug, prop).

Note the super sano trimming of the cowl. This expert modeler ensures there’s clearance at the head, the exhaust header, and for the needle valve.

Honestly, it’s a pleasure to see such high caliber work still being practiced by some.

So the truly expert modeler never mounts a brand new engine on a brand new model. Experienced modelers will, and so will rookies.

The rookies because they don’t know any better, the experienced ones because they believe they do. And the experts? because they eliminate all opportunities for Murphy to disrupt the first flight.

Basically, the expert first, allows as engines are expensive. And second, breaking in the engine on the test stand allows the modeler to control all variable on the ground immediately instead of in the air where a lean run likely means damaging the engine.

Said engine damage being permanent. And repair adds to the expense. So a few hours one day performing a break in is an profitable use of a modeler’s time and an enjoyable way of ensuring the first flight sees you concerned only for the model’s trim and balance instead of fretting about the engine.

So if we’re going to touch on engine break in, allow me to offer up a DVD showing the ins and outs of doing it. It’s called aboutENGINES and will set you back a double saw buck.

And for your $20 you get details about not just engine break in of both2-stroke and 4-stroke engines but gassers, also. That, and how to disassemble the engines, adjust valves, rebuild Walbro pump carbs, and more.

The video runs +3hr and the beauty of is you bring your ears into the game to hear what the engines sound like both rich and lean. After all, why take years to learn what the pros know?

Side-mount 4-stroke

Next, let’s touch on side-mounting a 4-stroke. With their unique sound and torque characteristics, many modelers prefer the throaty roar of the 4-stroke to the more harsh rasp of the 2-stroke operating at higher RPMs and firing on every stroke of the piston. As the old Yamaha commercial put it, different strokes for different folks!

A shout out to Larry Tener for this shop photo showcasing the superb installation of a Saito 100. Offering a gracious plenty of gentlemanly propulsion, he made a very clean installation of the engine for his Kaos.

And the guy to thank for this next tip, regarding throttle linkage for a rear-mounted carb is Jim Johns. He drilled and tapped the engine mount for an arm and made a short linkage to the carburetor arm from ahead of the engine, which is quite a nifty application of out of the box thinking . . . and I’m stealing this idea!

Preventive maintenance

So a trick of experienced nitro fuel modelers is to know what lies in store. Not talking just about when the model has been flown a few times but after it’s had a season or three of use. This section is devoted to a few tricks of preventive maintenance.

First we’ll look at spending a few minutes applying a bit of clear to both the trim where it makes sharp edges and at exposed wood where exhaust and raw fuel will soak in with predictable results for the structural integrity of the wing root of the right hand wing panel.

Second we’ll look at how we can address a known trouble spot of the canopy latch. While there are as many ways to sort this as there are modelers, I’ll show you a neat method an experienced modeler developed using Popsicle sticks from the craft store.

First up, a spot of fuel proofing against the exhaust oil lifting the trim.

Fuel proofing

For example, highly experienced modelers will anticipate where raw fuel (as well as exhaust goo) will attack the model – and – more importantly, what may happen as a consequence. Then they’ll get ahead of the damage.

How? Simple, they’ll work at fuel proofing the raw wood a well as where trim makes sharp corners. This, because it’s where it changes direction that trim comes down to a point and becomes vulnerable and prone to lifting up, thus spoiling an iron-on film finish.

For this photo we have Jon Wold of Norway to thank once again as he expertly showed the way in terms of fuel proofing. This time, both at the root rib, which is bare wood, and at the corner where the trim changes direction on the engine side. Both vulnerable areas.

Upper hatch PM

As many Kaos owner have discovered, the nifty pin-type latch securing the upper hatch of the model may fail. Since it’s accessed after every flight with electric models for battery maintenance, then this is unfortunate.

Especially because it means, a) the risk of losing it altogether, or b) it gets damaged in the fall to earth, and maybe worse, c) you can’t buy a replacement. Better to do a spot of preventive maintenance, eh?

So this experience modeler used a couple of Popsicle sticks epoxied to the sides along with hardware store plastic drywall crew anchors and ginned up a better solution. A couple of screws and presto!

Could you use magnets, or another method? Yes, of course, this is what modeling is about!

So consider Jim Johns approach, with a brilliant example of lateral thinking as a Popsicle stick and drywall anchors tangibly improves the model’s day in day out utility. It’s savvy modelers like this who help move the sport forward by sharing their tips and tricks.

So I’d like to once again give thanks for the folks who shared their various tips and tricks plus photos. If you have an idea you think is neat, share it with me and we’ll add it to this document.

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 if we’re to stand a ghost of a chance against the big guys. 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!