RC Helicopters
Eric Hawkinson, 319 Yellowstone Ave., Billings MT 59101; E-mail: [email protected]
IT'S ANOTHER great month to enjoy Radio Control (RC) helicopters! I have been getting in a few flights every weekend most of the year since last May, which is a lot of flying for me compared to the last few years.
Unfortunately, I had a five-week stretch—including most of June—where I didn't fly or get much of anything done, except the minimum to keep up at work.
A simple cold turned into a nasty infection that outlived several antibiotics, and just as that was starting to ease, I had two root canals done that resulted in another infection that put me on my back for more than a week.
I missed the deadlines for two columns, but luckily one of them was the Nats issue which was covered by another writer. Congratulations to all for a great event.
I'm fine, and I'm back, and you have my sincere apologies for missing an issue.
While I'm making apologies, I need to make one to JR.
In my September 2001 column, while discussing throttle setup for aerobatics, I wrote:
"You will probably need to make sure that the throttle-channel endpoints (ATV [Adjust Travel Volume]) are set at maximum and full stick is at 100% on your throttle curves.
"The reason is that you will want to use a cyclic-to-throttle mix for aerobatics, to mix in the power needed to perform the maneuvers. You can't manually add throttle during a flip or stationary roll because you would be changing the pitch setting.
"With most radios, this cyclic-to-throttle mix can overdrive the throttle servo if you have not already maxed out the travel adjustment on the end. (The Futaba 9ZH and Airtronics Stylus with helicopter cards are the only ones I'm aware of that don't have this issue.)"
Oops. It turns out that the JR 10X helicopter radio also has smart programming that prevents the throttle servo from being overdriven by the above types of mixes.
The reason I missed this—in spite of owning a 10X—is that the radio only recognizes the throttle travel settings made in the ATV screens as absolute when you use the preconfigured mixers. The 10X has these preconfigured mixers for elevator-to-throttle, aileron-to-throttle, and tail-rotor-to-throttle.
When I got my 10X, one of the first things I did was to use a standard (not preconfigured) P-Mix function to see if the cyclic-to-throttle mix would overdrive the throttle. It did, no matter which function I assigned as the master.
I figured that the 10X was like most other radios and would need to have the travel volume maxed out to prevent linkage binding. If I'd taken the time to try preset mixers one at a time, I would have known better.
Some pilots never have "enough" power ...
Live and learn, I guess; I now like my 10X even better!
This has been—and continues to be—a big year for our sport. One area that has seen a lot of changes and improvements is power systems, and nowhere is the change more significant than in the .50 class.
For years, the .46-size helicopters have been in a kind of a no-man's land; they cost more than the 30-size helicopters and promised higher performance. Unfortunately, most of the engines in that size were less-than-splendid in behavior. The most readily available .46 was the O.S., but it was (and is) extremely difficult to make that engine run smoothly.
Many articles and Web sites have posted various solutions and most make a difference, but in general I have never been very happy with my .46 helicopters because I have never been happy with the engines.
Not anymore! The new O.S. .50 SX-H is as perfectly well-behaved as the best helicopter engine you have ever seen. It starts easily, runs smoothly at all throttle settings, and has a big power advantage over the .46.
The carburetor is similar to the fine-working, two-needle carburetor that O.S. used on its .61 LX-H and works equally as well. It has a bigger bore than the old .46 carburetor, and the porting inside the engine is much more aggressive. The result is an extremely powerful, reliable, and smooth helicopter engine.
There are really only two things about the engine that are "bad." It drinks a lot more fuel than the .46, and it has too much power for some airframes. The first problem can be addressed in most helicopters by adding a larger fuel tank.
The power issue is one that you can control to some extent by making sure that you only use the power you need. Do not use the added power to run obscene high head speeds! You should probably check with the manufacturer to be sure that your helicopter is designed for the power of the O.S. .50.
I currently have many cases of fuel through the O.S. .50 in my Kalt Mercury M, and it is one of the hottest and smoothest helicopters I have ever flown!
I changed out the stock blade grips for the aluminum upgrade grips with four-millimeter bolts and used the high-quality KSJ shoulder bolts. I also keep the head speed to approximately 1,700–1,800 rpm maximum.
With this setup and Vic Campbell's 600mm V-Blades, the helicopter climbs faster than any I've owned, even when the engine is set fairly rich. The engine has been absolutely trouble-free since the first tank of fuel.
You will probably find that retrofitting the O.S. .50 SX-H into your existing helicopter is no problem because the mounting dimensions are all identical to the O.S. .46 FX-H.
If your helicopter has a flywheel with a flat spot on it for the .46, you will need to machine it so it is round—most do not.
You will probably also need to change to a muffler that is designed for the O.S. .50; even though the muffler mounting is the same as the .46, the exhaust volume is not. My experience has been that the KSN 46 muffler and Kalt's .46 muffler work okay; most others are too restrictive. I used the Hatori 50 mufflers with great success and KSJ will have a new 50-size muffler available soon.
So far my experience has been that the O.S. .50 works fine with the same gear ratios as most .46 engines, even in most 30 helicopters.
I hope this engine will spur even more development in the mid-sized helicopter kits. Hirobo's upcoming new Seagull 50 is designed for the engine, and it even released an upgraded GPH kit to handle the O.S. .50.
The long-boom version of the JR Ergo 46 is also a perfect mate for the .50, and between the longer boom, blades, and the huge power upgrade, it's a completely different machine from the standard Ergo 46.
Transcribed from original scans by AI. Minor OCR errors may remain.
