CONTROL LINE RACING
Author
Dave McDonald Box 384, Daleville IN 47334 E-mail: DMcD143@aol.com
Introduction
This month's column is proving somewhat difficult to start. I had intended to report on a racing contest in Florida, but the FAA scheduled some testing, resulting in the loss of the contest site for the scheduled weekend. Gabe Manfredi did yeoman's work notifying those who received a flier about the postponement. Gabe tells me they are working to reschedule the event; it will probably be in the fall.
I had hoped to use the event to test a new Scale Racer for the Nationals.
Weak Signals RC Expo (Toledo, OH)
I just returned from the annual trip to the Weak Signals RC Expo at Toledo, OH, April 9–11. I've never been to the Toledo show; it is something to see. Not many items are directly related to racing, but every once in a while you find something worth dragging home.
This year I was surprised to find a source of ceramic ball bearings for racing engines. I enjoyed a 25-minute discussion with Allen Baum of Boca Bearing. Allen is knowledgeable regarding bearings and took plenty of time to answer questions about the use of ceramic V-steel bearings.
The ceramic balls provide less friction, which should equate to more output. They should also require less lubrication to maintain peak condition, and they will not rust as most bearings do. If you would like more information, contact Allen Baum of Boca Bearing (address in Sources). I will give a more detailed analysis after I have used the bearings for a while.
Irvine .15R
I acquired an Irvine .15R and have begun testing and attempting to develop this engine for a limited Goodyear event run locally. This engine's similarity to the Rossi .15 is striking. The Irvine features a bushed connecting rod, ABC piston-sleeve combination, and a polymite retainer rear bearing that measures 12 x 24 x 6 millimeters.
The Irvine was extremely clean when I received it and showed a high degree of quality workmanship. It had a .308 venturi and a .315 crank hole. Prior to running the engine I made an initial modification to the head: I drilled and tapped the stock head to accept a Nelson plug (the engine as received had a built-in plug in the head).
Modifications and results:
- Opened crank to .375.
- Opened venturi to .360.
- Added a pressure tap to the backplate.
- Raised the exhaust timing by 7°.
Result: rpm increased into the 27,000 range.
Initial running showed good rpm — not consistent with my Nelson or Gillott Rossi, but improvable. The problem with the Irvine is that the piston-sleeve fit went away rather quickly. That can be corrected by sending the engine to have the sleeve chromed, which is relatively inexpensive.
The Irvine comes with a spinner, but the Nelson .15 front end will work fine on this engine. So far, the Irvine is not yet on a par with my Nelson or Gillott Rossi, but it should provide good power and potential for those flying limited Goodyear or who have the ability to develop an engine.
Norvel .15BB
The Norvel .15BB is the first engine I know of that features AAO (Aluminum-Aluminum-Oxide) Ceramic Seal Cylinder/Piston technology. Norvel indicates this technology offers longer operating life, cooler running, fuel efficiency, improved cleanliness, and more power.
This engine has a one-piece high-silicon-content cylinder/head/sleeve. According to Norvel, the benefit is its ability to maintain a better seal, dissipate heat, and provide more power. The Norvel is fairly clean and of good quality. It comes with a round connecting rod, but it is not bushed.
Initial examination showed very low exhaust timing, which may in part account for lower performance. In box condition I achieved 19,200 rpm. After making a new venturi and lowering the plug height approximately .020, performance jumped to 21,200 rpm. I think further modification — a new-style head, opened crank, and yet larger venturi — may yield more performance.
I was concerned that the exhaust timing was only 13°8' and that there was limited opportunity to raise it because of the mating of the sleeve to the case. The engine does provide good restart capabilities. It should be a good, economical engine for sport use and offers interesting possibilities concerning AAO piston-sleeve technology.
Propeller Molds
I have received correspondence regarding where to get props molded. Walt "Wally Gator" Perkins of Ocala, Florida has made a couple of molds for me. They are highly accurate, quality workmanship aluminum molds that should last an entire modeling career.
Walt will either make a mold and send it to you or make props for you. If you want to make props yourself, he provides extremely detailed instructions—so detailed that a person who has never made a prop can do so with minimal effort. Walt also has a very good assortment of racing supplies (mainly for F2C), including interesting accessories such as retractable landing gear for an F2C model.
Decals
Would you like to make your own decals? Labco sells a decal starter kit, which includes three sheets of blank decal material and an instruction booklet with many hints and tips. These decals are water-transferable (not vinyl).
You can make an image on a computer, print it on paper to preview how it will look on your airplane, and if you like it, insert the Labco decal sheet into your laser printer and follow the instructions. When finished, you will have that one-of-a-kind decal you always wanted.
Propeller Balancer
With some simple machining you can have an inexpensive and effective prop balancer for use in the shop or at the flying site.
Steps:
- Determine the type of prop you want to balance and acquire two flanged ball bearings and a drill blank the same size as the hole in your prop.
- Get a piece of aluminum approximately 1-1/3 inches long and 1 inch in diameter.
- Put it in the lathe and bore a hole through it. The hole size depends on the outside diameter of the bearing you will use.
- Mill a flat area down the length of the aluminum to provide a base that keeps the round balancer from rolling away.
- Insert the bearings at each end and the drill blank into the center hole.
- After the drill blank is installed, use two small O-rings to keep the prop on the shaft during balancing operations.
The result is a simple and effective prop balancer.
NCLRA
Are you a member of the National Control Line Racing Association? The newsletter is full of tips and information. Dues are $10 US or $12 outside the US. Send to: Dick Lambert 4651 Ridgewood Ave. Port Orange FL 32127
Your contributions and comments are solicited and appreciated.
Sources
- Boca Bearing
7040 W. Palmetto Park Rd., Ste. 2304 Boca Raton FL 33433 (800) 332-3256
- Walt Perkins
4416 SE 4th Pl. Ocala FL 34471
- Labco
27563 Dover, Dept. BR Warren MI 48093 (810) 754-7539
Transcribed from original scans by AI. Minor OCR errors may remain.
