Free Flight: Old Timers
Clarence Haught
Odds and Ends
Some time back we commented on a few unusual contest names. Bob Lundberg, secretary/treasurer of the "Western Lake Superior Flying and Hiking Society" (whew!), a multiple-interest club in Duluth, Minnesota, wrote to tell us about the "Third Annual Frozen Feet Meet." Bob states, "This meet is held the second Sunday in March despite the weather which usually is in the 20 degree range with one or two feet of snow still left from the ravages of winter. Only one event is flown—Outdoor Handlaunch Glider." Not only is this club not lacking for words, they're not lacking enthusiasm either!
Hans Ochsner, of Metamora, Michigan, mentioned a good tip in his recent letter. "An added note of caution, isolate fuel tanks from engines that turn high rpm. My experience is that about 12,000 rpm, attached tanks are instant foam, dropping rpm until the fuel again becomes liquid, then picking up again until it foams. The high-low cycling won't fly your airplane." This would be most prevalent in conversions, as most of the original ignition engines won't turn up that high.
Incidentally, you may recall pictures of Hans' "homemade" engine conversions a few columns back. Hans has provided the necessary information to guide the interested modeler in converting his own engine, which we will publish in our next column. Watch for it!
Now and then we get an inquiry about condensers. Most any type of condenser will work if it is the proper size range. Recommendations:
- Capacitance: 0.1 microfarad (one-tenth µF)
- Voltage rating: 200 to 400 volts
- Avoid wax-sealed condensers; gasoline will penetrate them
- Epoxy-sealed types are best
- Many condensers are fitted with single-strand wire which won't stand much vibration: mount the condenser securely and support the single-strand wire with epoxy glue; keep the single-strand lead length to a minimum
- While at the electronic supply house, pick up some 18-gauge stranded wire for wiring your ignition circuit; smaller wire leads to hard starting and poor reliability under field conditions
Art Hemler, of Glendora, California, shares his experiences with some of the later versions of the Cox .020 engine used for the .020 Replica event. It seems that the new production engines are being equipped with aluminum needle-valve housings instead of the previously used iron housings. Art has found some of these to be drilled and/or tapped off center, affecting fuel metering and vaporization. Needle-valve threads are rather coarse, resulting in sensitive needle settings—either too rich or too lean with a slight adjustment. There appears to be a market for a fine-thread needle-valve assembly to fit the .020, similar to the special needle valve for the TD .049 developed by Kirn. If memory serves, the Kirn needle valve had a thread pitch double that of the issue needle valve.
Another problem is in the indexing of the cylinder to the crankcase, resulting in exhaust ports directing hot gases directly against the plastic fuel tank. This apparently only occurs in a few engines and would require costly hand-fitting for the manufacturer to correct. If you own an engine with this problem, it would probably be worthwhile to try a shim under the cylinder to correct exhaust port alignment.
I share Art's concern over the often cantankerous .020 engine in the hands of newcomers to our hobby, particularly Juniors. Cox Baby Bee .049 engines are much easier to manage and hence the subject of our Old-Timer event of the month.
Old-Timer Event of the Month
Half Scale
While not the most popular of SAM special events, Half Scale does have a great deal to offer. Basically an event for half-scale Old Timers powered by the abundantly available .049 engine, its popularity has usurped the .020 Replica event. Contrary to the .020 Replica, which has become an all-out competition event, Half Scale is still a fun class. I feel the event has the greatest possibilities as a beginners' event.
Half Scale offers a home for the many cast-off engines from plastic control-line trainers. The Cox Baby Bee .049 offers ease of starting, readily available parts, and can be "souped up" to nearly TD .049 performance by replacing the stock cylinder with a twin-intake-port cylinder from the TD or the 290 series engines and using a TD glow head. They can be adapted to squeeze-oiler timer operation by drilling two .035-inch holes in the side of the tank and routing the fuel pickup line from the needle-valve inlet out through one hole to the timer and back into the tank.
For sport flying, simply rotate the tank until the fill and overflow lines are horizontal to limit fuel capacity, and time the total engine run with a stopwatch. After determining the run time in this manner, flight engine runs are regulated by timing before releasing the model, thus avoiding the cost of a timer.
Why not give one of those extra Baby Bees to the kid down the block just itching to get into model airplanes?
The half-scale size requirement provides an unlimited variety of subjects and, while not the intent of the rules, many old-time designs are already just right for .049 power and make ideal subjects for beginners.
Since this is a special event, and not flown in national competitions, why not allow full-size designs to be used on a local Contest Director (C.D.) option basis? Examples include:
- Musketeer 42
- Taibe's Winged Yankee
- Miss Tiny
- Rocketeers
In fact, most designs for the .09 to .19 engine range are readily adaptable for Baby Bees and will perform quite well. I have a Musketeer 42 that flies great on a Cox 290 special engine. I have flown the ship in competition in the combined Glow class popular here in the Northwest. It could be flown in competition with ignition engines by using the Glow engine run penalty rule.
Rules require the construction techniques be the same as the full-size counterpart, using appropriately smaller wood sizes; substitution of sheet for built-up structure is not allowed.
Clarence Haught Rt. 5, Box 16 Coeur d'Alene, ID 83814
Transcribed from original scans by AI. Minor OCR errors may remain.
