Author: Ray Stacy
Edition: Model Aviation - 2005/03
Page Numbers: 108,109,110
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RADIO CONTROL HELICOPTERS

Ray Stacy 15 W. Main St., Webster NY 14580 E-mail: [email protected]

Introduction

Will James of HeliFreak.com approached me last year and asked if I was interested in reviewing a new helicopter from Gohbee Aviation (www.gohbee.com). I am always interested in anything new for our hobby, so the answer was “Yes.”

Stinger 30

Within a few days a box containing the Stinger 30 arrived on my doorstep from Gohbee Aviation. This model is best described as a combination of the Raptor helicopter with the Caliber head. It was an enjoyable aircraft; you can read the full review at www.helifreak.com.

O.S. .37 engine and Muscle Pipe II

At the same time I received a new O.S. .37 engine (available from www.osengines.com) to test on the Stinger, along with a Muscle Pipe II (www.curtisyoungblood.com). If you are looking to put new life in your 30-size machines, the O.S. .37 is the ticket — extremely user-friendly and smooth running, with nearly 50-size performance.

During testing I tried a variety of standard 30-size mufflers with mostly unimpressive results; they wouldn’t let the .37 breathe. The Muscle Pipe II brought the engine to life. Curtis Youngblood has done a nice job with the design of this pipe: it helps the engine make power while acting somewhat as a governor to help control rpm.

Stinger 50

At our local helicopter fun-fly last August I met David Ellison of Gohbee Aviation. He drove up from South Carolina to participate in our event and drop off the Stinger 50 for review — at the time it was the only one in the country.

The Stinger 50 is more than a scaled-up version of the Stinger 30. It is available in several configurations:

  • Canopy options: plastic canopy with a see-through windshield, or a nicely finished fiberglass canopy.
  • Blade options: offered with or without MAH 600mm carbon-fiber blades.
  • Head: a beautiful all-metal head with an aluminum pitch arm (similar in feel to the Caliber’s head).

I like the Stinger line’s flying characteristics. The machine has a nice, solid feel in a hover yet is extraordinarily responsive during aerobatics. In fast-forward flight the helicopter tracks beautifully with no tendency to balloon.

O.S. Hyper .50 installation and clutch setup

After hearing the hype about the O.S. Hyper .50 engine from my buddy “Jim the Wasp,” I bought one and tried it in the Stinger 50. The Hyper .50 is a snug fit because of the larger cooling fins, but it will fit without modification. Mine came with a standard-type muffler, which I installed for initial testing.

The Stinger uses a clutch with the start shaft pressed in. Take the time to dial-indicate the clutch:

  • Initially I had .006" runout.
  • By rotating the clutch 180° I was easily able to get it below .002" TIR (total indicated runout).

Early flight impressions and overspeeding

I only had a few flights on the Stinger 50 before winter set in, but all indications are positive. On the first flight I hovered while dialing it in; the biggest problem was stopping the engine from overspeeding. This engine wants to run — I had to keep tweaking throttle curves and the mixture to try to hold it back. A governor would help, but I wanted to get as close as possible before adding one.

I purchased two governor/limiter options to evaluate:

One of these may soon find its way into the Stinger.

Durability testing

On the second flight I deliberately pushed the Stinger hard to see if I could find any weaknesses. If a boom strike or mechanical failure was going to happen, this was the time. The Stinger 50, like the 30, goes where you point it and hangs in there until you tell it to stop. There was no engine bogging. I did eventually break a head link when I botched an autorotation and stopped the blades by sticking them in the ground; the only damage was a plastic blade link.

Important note: Gohbee’s ball links are slightly larger than standard. That means swapping links from another machine is a bad idea. When I last spoke with Gohbee, I was told the company planned to change to the standard 2mm balls.

I’m looking forward to a few mild days here in upstate New York so I can put more time on the model. David Ellison is excited about the product and eager for feedback; he is constantly looking to change and improve. Stay tuned as I get more time on the Stinger 50.

JR XP9303 (JR XP9303 RC system)

I have been using the new JR XP9303 RC system since it came out. It replaced two 8103s, and my 10X hasn’t been getting much use. I especially like the new thumbwheel programming, 30-model memory, and full Cyclic Collective Pitch Mixing (CCPM) support.

I recently received a note stating that the 9303 has a programming glitch in the 140° CCPM setup. There is a workaround to use until a software fix is available from Horizon Hobby.

Problem: The fore/aft cyclic control programming does not allow the aileron servo to travel as far as the elevator servo, which would cause the helicopter to veer left or right when fore/aft cyclic input is given.

Workaround:

  1. Go to "PROG. Mix4"
  2. Activate "ELEV-AILE" mix
  3. Set both POs to the same negative value (start around -40% to -45% as an initial setting). Adjust as needed so the fore/aft cyclic throws are even. Make sure the upper and lower values are set equally.

This will allow the fore and aft cyclic controls to throw evenly without upsetting any other CCPM controls. My final values ended up being roughly 30%, but yours will vary and must be adjusted until the throws are even.

Transcribed from original scans by AI. Minor OCR errors may remain.