Radio Control: Helicopters
Larry Jolly 15781 Empire Ln. Westminster, CA 92683
WELCOME BACK. I have quite a few topics to cover this month, so let's jump in.
P.A.R.R. Field Charger Update
I just heard from Mr. Ray Stacy, editor of the P.A.R.R. Newsletter. As you may recall, I published a schematic for a low-cost field fast charger in the January issue — a schematic that I had taken from the P.A.R.R. newsletter.
As things turned out, it would have been better to publish it in the April issue, because as presented the charger doesn't work. Quite a few of you have already found this to be the case. Ray told me he has been receiving seven to ten calls and/or letters a day for the last several weeks.
To put an end to the mystery: the indicated light bulb is a #67 12-volt automotive bulb. In addition, you must switch the 150-ohm and 2700-ohm resistors. That's all there is to it. Several readers have told me that after these changes the charger works great.
As a side note, Ray said that even though there was a problem with the drawing, it gave him a chance to meet and converse with a lot of nice folks. I agree — it's a good experience to integrate with modelers outside your area. It gives you a broader view of the hobby.
By the way, the Pittsburgh crew is working on an inexpensive battery-discharging system for field use. As soon as they have the system working and the schematic double-checked they'll send a copy to share. Many thanks to Ray and the P.A.R.R. guys, and good luck to you with the fast charger.
Tech Specialties Mini-Elite Rotor Head
Bill Curtis of Tech Specialties sent me one of their new Mini-Elite rotor heads to try out. G.M.P. originally planned to produce a 30-size head, but those plans were side-tracked by G.M.P.'s demise. Bill Curtis decided to improve the original design and manufacture the head himself. The unit I received is shown in the photographs accompanying this article.
The Mini-Elite head is of the highest quality. The entire unit is made of metal — mainly aluminum. Key features include:
- Underslung flybar and single axle
- O-ring-style individual dampeners
- Ball-raced blade holders and mixer arms
- Ball-raced flybar support and seesaw
- 1/4-inch aluminum blade arms for excellent tracking stability
The basic design geometry is similar to the X-Cell, Champion, and G.M.P. Elite. The Tech Specialties head is available in two versions: one for the Hirobo Shuttle and one for the Kyosho Concept.
I used the head to update an older Hirobo Shuttle, bringing the ship up to modern standard. For rotor blades I chose a pair of fiberglass Mini-45s from Vortex RC; I also used a pair of K&S tail rotor blades. The Mini-45 blades weigh about 120 grams each and are CG corrected.
Before testing I made two changes:
- Removed the ball riveted to the flybar arm by carefully filing the rivet flange inside the arm until the rivet fell off, and then replaced it with a ball secured by a 2-mm screw.
- Used two nuts to space the ball links about 1/8 in. toward the main shaft. This gave the ball links a better operating angle and greatly reduced drag.
I spent several evenings at the local schoolyard flying the updated Shuttle. It's very responsive — every bit as lively as my Shuttle ZX and seems to handle even better, possibly aided by the Mini-45 blades.
The Mini-Elite head performs superbly in hover and shows no tendency to hunt or flutter during hard pull-outs. With 1/4-in. aluminum blade arms, there's virtually no way to get blades out of track. I recommend it wholeheartedly.
I also flew a Tech Specialties head on the Kyosho Concept 30; it produced noticeable improvement in stability, particularly in wind. The Concept gained a whole new personality with the head change.
Tech Specialties contact: Tech Specialties, 218 Vernon Road, Greenville, Pennsylvania 16125. Phone: 412/588-1335. If you haven't dealt with them before, drop them a line for their product listing — they offer many useful after-market items including blades, canopies, hardware, and a large stock of G.M.P. parts. I understand the Tech Specialties Phoenix is now available; I'll report on it as soon as possible.
O.S. .32 Modification
A friend, Tony Davis of the O.C.R.C., discovered a simple modification to the O.S. .32 that yields more power. Tony found that an O.S. 4D carburetor (as used on the O.S. .46), turned down slightly (about .015 in.), will fit the O.S. .32. The 4D carburetor has a significantly larger throat than the stock .32 carburetor.
I tried the modification myself; it was easy and required only about ten minutes of lathe work. My engine definitely puts out more power and doesn't seem to suffer fuel draw or needle adjustment problems. I recommend using muffler pressure and, for maximum consistency, a header tank mounted close to the carb. If you need a bit more power for your .30-size rocket ship, give Tony's idea a try.
Rotary Wing Modeler
There is a new U.S. magazine dedicated to RC helicopters: Rotary Wing Modeler, edited by well-known flier Mike Mass. Mike has been in the game a long time and seems serious about doing a good job. Besides setup articles and product reviews, Rotary Wing Modeler will also act as a voice of IRCHA. If you'd like to subscribe, contact Rotary Wing Modeler, P.O. Box 420, Manalapan, New Jersey 07726.
Electric Helicopters
Many readers and I are interested in larger electric RC helicopters. I know at least two 40-size machines were flown at Keystone this year. If you are working on a larger electric machine and would like to share your findings, please drop me a letter. If possible I'd like to include your results in a future column. I'm working on a Heim conversion with an Astro 60 and 28 cells; I'll report back when it flies.
66th National Championships
It's time to start making plans for the summer Nationals. The 66th National Championships will be held June 20–29 at Westover Air Force Base, Chicopee, Massachusetts. Helicopter events will be flown Saturday, June 20 through Tuesday, June 23. Deadline for advance entry is May 22. Contact A.M.A. Headquarters for entry forms and additional information. See you there!
That about wraps it up for this month. I hope you're getting some flying time in. I've just finished a Kalt Baron Alpha II, and I plan to let you know what I think of it next month.
BCNU
Transcribed from original scans by AI. Minor OCR errors may remain.
