RCDOM 2010


 

03/19/10- My previous foray into the world of Radio Control was the 1:16 scale RC tanks from Tamiya and Heng Long. Although RC tanks are fun to drive, they're relatively... pokey. That's okay if you're in a laid-back mood, and on occasion the idyllic serenity of the backyard in the afternoon needs to be shattered by amplified tank sounds. The pokiness is well-suited for driving the tank with an onboard video camera, showing the tank's ground-level perspective. The video game Tiger vs T34 takes that approach, and with its emphasis on realism, it's more of a tank simulator than a game. For the die-hard WWII tank buff, that is fun... but for me and many others who aren't die-hards, endless waiting and playing hide & seek isn't as much fun as playing something faster paced with a plot, like Mass Effect 2.

The building/modeling/tinkering aspect is what I like most about RC Tanks. The operational aspect shows the result of all my spending and tinkering ("Hot damn, it actually works!!!"), but I get bored driving them just for the sake of driving them, especially since there's little sense of risk and challenge (mainly, losing parts-- grrrrrr). For RC play, I've learned that I prefer a zone somewhere between a sedate, tankly pace and the stressful intensity of a high-stakes heli flight where I'm totally out of my league.

 

rc micro heli MSR Finally, A Single Rotor Radio-Controlled Helicopter That Even I Can Fly!

It's been said that of all the branches of RC-dom, radio-controlled helicopters are the hardest to learn and master. They may even be more difficult to fly than a real heli because you don't have the direct feedback loop of a cockpit view (yeah, but you usually don't die when an RC heli crashes). It's an ideal hobby for someone who likes personal challenges. It doesn't require teams or competition, since leaving the field with an intact heli is reward enough, as I see it.

If you consider yourself a failed RC heli pilot -- a realization that you might reach after having destroyed and repaired your Trex 450 one too many times -- there's hope for you yet! It's in the form of Eflite's MSR ("Micro Single Rotor") heli. It's a true single rotor heli that you can fly indoors, crash into your TV, pick up and fly again, all without breaking things and hemmorhaging money on replacement parts. Wow! What a concept! Part of that is due to it being a fixed pitch heli. It doesn't suck your heli to the ground when you pull the stick back, and it's a very stable design. Mainly, I suspect that it's due to its small size and the magic of physics and scale mass. At this size, parts can be very strong without adding a lot of weight, so it doesn't take a hefty powerplant and heavy cells to get the thing airborne. When it flies into immoveable objects, it's sort of like hurling a fly against a wall. The fly may be stunned, but won't splat like we humans would. (However, just like its larger brother, the MSR can do "The Chicken Dance"!)

Because it's a single rotor heli (versus a coaxial), this sucker is agile, responsive, and fast. Things can go south in the blink of an eye, so there's an aspect that's somewhat like driving the Trex, but minus the "pucker factor". That's a huge difference since second chances with a Trex come with a hefty price tag and a lengthy rebuild time. Although I'd picked up a bit of confidence from flying the MSR, as soon as I spooled up the Trex, I had a premonition of big bucks flying from my wallet. (Which is why I was able to take the pic of it intact, below.)

rc micro heli MSR Trex
You can take pictures of the MSR outdoors, but you really should fly it indoors.


RC10 Team Car Vintage RC Cars and Beyond: RC10 Team Car

By my reckoning, radio controlled cars are a rung below winged aircraft in the hierarchy of RC risk-taking prestige. Modern brushless motors and high-capacity Lipo batteries introduce much more risk than the relatively staid electric RC buggies of yesteryear, and slamming into a wall at 60 mph will break something. On the other hand, you can drive more conservatively and still have fun; with helis and planes, you won't have much fun unless you leave the safety of ground.

I recently rediscovered my vintage RC autos from circa 1990, which were my first serious/expensive venture into the world of RC. I hadn't messed with them much during the last 20 years-- the old Futaba Magnum Sport Jr. controller's battery holder was very iffy due to its poor design, and the cars' old 1200 mAh NiCad powerpacks gave only a few minutes of run time. Thanks to my new RC tanks though, I now had four 4200 mAh NiMH powerpacks to play with; I was willing to splurge a little on a modern 2.4 GHz radio and transmitter, the Spektrum DX3e (truly a bargain).

The low-slung 1:10 Kyosho Testarossa wasn't designed for running on our street, at least not since the street was repaved on the cheap with a coarse gravel-asphalt surface with most of it in the form of loose gravel. At a slow speed, it looks like the car is attached to a vibrator.

The RC10 Team Car is a different story. What a hoot! Not only does the sucker scoot on our paved street, but it kicks up dust storms in our rustic back yard, bounding over exposed tree roots and plowing through tall grass and leaves in a roughly designated "course" around two trees. It's very chaotic, and neighborhood cats love to stalk and chase it. This is in stark contrast to the uniformity of the RCP foam indoors track that the 1:27 scale Kyosho Mini-Z RCs run on. Those guys like clean, flat surfaces; lap after lap of the high-grip traction and responsiveness can be fatiguing and become a little tedious. Practicing begins to feel like work when it should be fun.

I was surprised to discover that "Vintage RC10" is a Google-able search phrase, and there's a substantial bit of ongoing discussion about the topic. Much of the talk is about restoring them to shelf-queen condition, but some folks look for replacement parts and substitutions to fix and run them. While many of the original parts and hop-ups are no longer manufactured, some are available on eBay, some parts from newer incarnations of the RC10 can be adapted to fit, some parts are common to all RC10 incarnations, and some are still being produced (like the body shell). I had such fun running and tweaking it that I bought a second Team Car on eBay, presumably so I could race with SWMBO (...when will I ever learn?).

My biggest concern was about the tires; if you run them, they get worn out and eventually will need to be replaced. Unfortunately, the standard size buggy wheel got larger after the vintage style RC10 line ended in the mid-90s; currently the standard appears to be 2.2" in diameter. Although you can still find tires that fit the old wheels, the pickin's aren't very good and they're expensive.

Fortunately, it's not too hard to replace the stock wheels with some that will fit the larger diameter tires, and Google eventually provided the answer: For the front, you don't need new axles to fit RC10B4 wheels. You only need to replace the bearings with those that have a larger outside diameter to fit the modern wheel. Avid.com is a great place for bearings.

The rear wheels aren't quite as easy since there are two issues: One of the issues is how deep the axle-wheel mounting is-- the vintage RC10 has shorter arms than the current RC10B4, so the RC10B4 wheel rims will rub against the shocks. Fortunately Duratrax's Nitro Evader rear wheels have a shallower inset. With these wheels, you'll have to enlarge the axle hole slightly. Then you have some options for mounting: You can use the RC10's (Team Car and newer) universal drive shafts by using Dremel's rounded cutter bit to enlarge a shallow section of the wheels' inside mounting area so that the parts mate properly. If you don't want to Dremel the wheels, you can replace the old universal drives with MIP's CVD that have the correct flush-mount fit for the Duratrax rear wheel. If you go this route, you'll also need new flanged bearings to fit the CVD shafts. Warning: Don't waste money on the Duratrax tires, since they don't have any traction at all! Pro-Line's Dirt Hawgs and Hole Shots work great.

To match the configuration of the two RC10s, I wanted to swap the eBay-bought RC10's 1990 Novak 410-M1c ESC for one with reverse to match the Novak 610-RV in my original RC10 (these are for bashing, not racing). I didn't want to spend a fortune on a replacement, so I bought Novak's budget sports model, the XRS. To be honest, it was quite a disappointment. Superficially, it doesn't have the "cachet" of the classic vintage Novak ESC-- it has a transparent orange enclosure, and apparently doesn't need heat sinks. I guess I expected more ESC for the money considering all the years that have passed, but it's a bare-bones reversing ESC with a 15-turn brushed motor limit. (I unknowningly ran it with a 12-turn motor for a while and the plastic sleeve on the bullet connector melted!.) Even with a 27-turn motor, it gets pretty warm; I guess you get what you pay for...

It's tempting to want to see what the strides in modern technology could do for the powerplant and speed; however, that may not be such a good idea since modern brushless systems would probably chew through the transmission in short order, and original Stealth transmission parts aren't easy to come by. For sheer speed, it's smarter (and cheaper) to buy something that's currently produced, like an RC10B4, which is available as a ready-to-run brushless system. With greater speed comes more broken parts so it works out great that the parts are readily available. Naturally, all this made me curious: What is it like to drive a really fast RC buggy?

RC10 Team Car
Paint scheme on the left was copied from a pic on the Internet. Kudos to whoever came up with it!


RC10B4 Mamba Max Beyond Vintage: The Factory Team RC10B4 Kit

Although the RC10B4.1 Ready-To-Run is a great deal, I got the kit because I already had a radio/transmitter/servo set, wanted to choose the ESC and motor, wanted some of the upgrades, and mainly because I enjoy building things and tinkering. This time I was going to stock up on parts that might not be as easy to find when they change the design (the B4's been produced since 2003).

My brand-loyalty thing with Novak had been shaken, so for the brushless system, I went with the flow and got Castle Creation's popular Mamba Max with 5700 kV motor. According to their chart, it delivers from 35+ to 60+ mph, depending on battery configuration and gearing. Okie dokie. Although I was curious about speed, I thought it was wise to be conservative, so I targeted a 2-cell Lipo configuration and stocked up on a range of pinions and spur gears. Following Castle Creation's recommendations for tamer performance, I installed a 16-tooth pinion and an 87-tooth spur gear.

I bought a couple 7.4v (2 cell) Lipo batteries with a 5000 mAH capacity and 25C discharge rate; these were available with a hard case, which seemed like a good idea since Lipos can do really bad things if the foil envelope is pierced. Another cool thing about the hard pack design is that the leads aren't soldered on: Banana plug jacks tap the battery so you can wire the ESC with home-made right angle banana plugs to keep the wiring short and low-profile (which is an issue with the limited headroom inside the B4). The charging cable with balance plug stays with the charger.

I was surprised at how difficult it was to find the right Lipo charger. I have plenty of chargers-- AA, AAA, NiCad, NiMH, 1 & 3 cell Lipo-- but I didn't have one that would balance charge a 2-cell Lipo (since I'd given away my Blade CX and all its extras). I was looking for a charger that would balance charge Lipo cells, charge at a respectable rate, that could be powered by AC, and hopefully be universal enough to consolidate some of my collection of chargers. Any extra functionality and goodies would be a big plus.

There's no shortage of charger models, but most target the hardcore racer, not the casual backyard basher. Very few are characterized as "balance chargers"; for that, most require an external balancer gizmo to discharge cells to a balanced state. Also, most are powered by DC, with clips for a 12-volt battery. Some have jacks for an AC power supply but it's up to you to figure out which one to buy... another expense. For this casual basher, that's an extra level of complication that I didn't expect (or want).

The most economical route would have been to use Eflite's basic balance charger for their Blade CX line of RC helis, but it's slow and a one-trick pony. I finally bought the Turnigy Accucel 6, based on the good word-of-mouth received in forums. It appeared to do most of that useful charger stuff, like discharging/charging cycles for NiCads and NiMHs, and fast charging/balance charging for Lipos, with selectable current rates. Very neat, with many, many options. Unfortunately, it doesn't come with a manual so you need to Google for the .pdf version, and then bone up on your Chinglish translation skills.

It was also comparatively cheap-- an important point since I needed to buy a 12-volt DC power supply for it. I realized that a cheapie wall-wart wasn't going to cut it; the power supply needed to deliver a heavy stream of current for the charger to live up to its full potential. I found one in the RC airplane section of my local hobby shop.

Turnigy LiPo Balance Charger About Connectors and Cables: Another important point that I hadn't realized: You'll need a plan for how you'll hook all these things up, as well as a decent collection of connectors, heavy gauge silicone wire, a soldering rig, and some soldering skill. While I was awaiting delivery, I wondered about the plugs the charger and battery came with, and whether I was going to convert all my Tamiya plugs to Dean's plugs (as many people recommend) so that everything would be standardized. However, once I had all the stuff in one place, I realized that it wasn't necessary: It's all about making adapter cables.

The power supply, charger and hard pack Lipos all connect with banana plugs, so I bought a suppy of them as the basis for making adapter cables. For my NiMHs, I needed to make a Tamiya plug adapter cable. For my LiPos, I needed to make a balance charge adapter cable. Deans connectors were used as safety interlocks (although Traxxas connectors would be better) to help ensure correct polarity and to reduce the risk of shorts from bare banana plugs flopping about. In other words, the adapter cables were made of two parts: the banana plug to Deans plug (male) for charger output. The NiMH adapter: Female Deans plug and Tamiya plug. The LiPo adapter: Female Deans plug and banana plugs with balance charger plug.

Safety is the number 1 concern when planning this out, because you don't want to make sparks from shorting out your battery, charger or DC power supply. If you outfit a battery with a Deans plug, the plug from the battery should always be female. Male plugs have exposed prongs which will short the battery if they touch anything that's conductive, and batteries don't have on/off switches. Traxxas connectors are fully enclosed, which is why they're a better and safer choice in the realm of high current connectors.

Banana plugs are even worse since polarity is not enforced by an interlocking connector housing and the prongs are exposed and independent. If they're hot, they can easily short against each other from flopping around. Therefore, you never want banana plugs coming directly from a battery. There are times where it's necessary to have banana plugs at both ends of a cable run (like from the charger to a hard LiPo pack). In that case, it's important to either split the cable in two with a polarity enforcing enclosed connector and strictly follow a regimen when connecting the two. If you're connecting with a single cable, plug the charger side with the charger off, then plug into the battery (observing correct polarity, of course). It's then safe to turn the charger on. If you're using a 2-piece cable (with Deans or Traxxas connector in the middle), split the cable, plug each half into the charger and battery (observing correct polarity, of course), then plug the middle connectors together. (In this case, it doesn't matter whether the charger is on or off.) Doing it out of sequence (like plugging the middle connectors together first) defeats the purpose of this safety feature.

Oh Yeah, The Kit... The kit was fun and easy to build. As with the original RC10, the pictorial instructions make for smooth sailing, despite a few minor errors (i.e., no #2 shock piston is included, although the manual insists that it's important that you use the correct one). For convenience, I used a .pdf version of the manual which made the "actual size" parts matching useless; I guessed at which screws to use a few times (too lazy to haul out the manual), but it was pretty easy to figure out by the way the parts were grouped and packaged within the slew of tiny plastic bags.

RC10B4
Paint scheme inspired by Jim Clark of the '60s. Tires have seen better days...

The Factory Team kit is advertised as including a graphite chassis, but now actually includes the composite one. I only realized this since I had ordered a spare composite chassis because many folks had recommended it for its durability and more forgiving handling. I was confused when both appeared to be the same, and Google turned up another user's blog/site that seemed to confirm this. To be honest, I'm not complaining since the composite plastic seems very similar to the molded graphite shock towers and arms. In my opinion, it's not terribly flexible either, and feels/cuts like a glass-filled material. One way to tell is that the graphite parts will conduct electricity.

I couldn't help but compare the construction qualities of the vintage RC10 to the new one: It's a night-and-day difference, reminiscent of many other products that have gone through this evolution of production technologies. Although the 1980s and 90s weren't the epitome of quality industrial production and fine workmanship, the stamped and formed aluminum vintage tub has a definite vintage charm that distinguishes itself from the molded composite tub. However, the newer production processes give more freedom to produce from optimized designs: The molded tub has a more complex shape that would be impossible to produce in stamped aluminum. It also keeps production costs down, and it's hard to argue with that. Today, for a little over $200, you can get a prepainted, ready-to-run brushless buggy with ESC, servo, receiver and 2.4 GHz spread-spectrum transmitter. Back in 1990, $300 got you a kit with no motor, ESC, servo, receiver, or transmitter. Besides that, the newer version is designed to go faster, with a lower center of gravity and lots of little performance-centered design improvements.

And does it perform! With the stock setup suggested by the manual, a conservatively configured Mamba Max/5700kV combo (16T pinion/87T spur) and Lipo-powered, the sucker hauls ass. At full-tilt, the engine whine produces an audible doppler shift as it whizzes by. When acceleration is bumped as it's moving, the front shocks visibly unload, and I've learned not to floor it from a dead stop unless I want to see it do ugly backflips. A little less produces wheelies. Like the Trex helicopter, there's a bit of "pucker factor" when it's going full speed down a straight line: If the steering is blipped suddenly or sharply, or if hard braking applied when the steering isn't straight, there's a good chance that momentum will send it cartwheeling and flipping down the road. I've had a few close calls, and it makes driving the old RC10s seem sedate and relaxing.

The Mamba Max can be computer-configured with a USB cable and Castle's software, but I didn't feel the need to change much from the default settings. I added 20% drag braking, which I think smooths out the response a little when hard braking is suddenly applied; it also helps with turning. It models the response of a brushed motor when you let off the throttle and the magnets slow the car down. Without the drag braking (the default setting), the brushless motor lets the car decelerate much more gradually. Brushless motors are pretty amazing: When stopped on an incline, the brushless motor actually lets the car roll downwards.

Tire choice appears to be the single most important thing that determines how the car handles. When I was testing my eBay RC10 Team Car with new Duratrax spike tires, I had horrible problems with it oversteering on pavement. I tried all sorts of adjustments, but nothing worked and the tires were wearing down really quickly. Once I switched to Pro-Line Dirt Hawgs, the problems went away.


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