Author: Don Grissom
Edition: Model Aviation - 2010/01
Page Numbers: 122,124
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Radio Control Combat

Don Grissom [[email protected]]

A look at alternative glow engines for Combat

As we start the new year, there is one issue that everyone appears to be watching. This past year saw the end of the O.S. 25FX. This great Combat engine was reasonably priced and turned up a good rpm. O.S. has since come out with the 25AX, but there have been questions about its ability to produce the rpm needed for our event.

I looked into some other engines out there and found a few great alternatives. They may not be as good as a 25FX, but they will meet a Combat flier's needs.

One of these is the Magnum XL 28, which many Combat pilots have been using for years. It meets the rpm requirements but has carburetor issues at the high rpm at which Combat fliers run their engines.

The other problem with the XL 28 is vibration, which can cause the fuel to foam and air to get into the lines. This is not an issue with some models, but it might become one anywhere you have the engine close to the tank. Suggestions have included dropping the propeller to a 9 x 5 for Open B.

Another alternative to the 25FX is the GMS .25. Something most pilots notice about this engine is its price; it costs roughly half of what the O.S. does. But sometimes a lower price means more hassles.

Scott Gilkey, who has done a lot of work with the GMS, has tried many things that seem to be making progress toward turning it into an excellent Combat power plant. Some of the test runs using a Master Airscrew 10 x 4 propeller were at 13,600 rpm. After removing a shim, Scott got the rpm up to 13,700.

Then he changed out the carburetor to the type used on an O.S. .32, which gave him 14,200 rpm. It doesn't equal an FX's performance, but it's close; with the rpm limit set at 14,000, this would work very well.

With the Magnum, the GMS, and the O.S. 25AX, there are some good engines to use for Combat. A forum on the RC Combat Association Web site has suggestions for setting up these power plants.

It seems like when I talk about Combat, the topic is what is going on in the areas near where I live, in Georgia. But in 2009, one of the biggest areas of Combat participation was California. This past year has seen Combat grow to more than 26 members. A big part of that increase was making Combat easy and accessible to many people. The following is from Glen Kratz, telling us how our event is being cultivated on the West Coast.

Growing Combat on the West Coast (Glen Kratz)

"Several years ago when I decided to get started in Combat, I did not know what direction to go, where to start, what kind of and where to get an airplane. Face it; I was just a total 'rookie' to the Combat arena. Enter the Palomar RC Flyers Combat group.

"Palomar has been known as the 'Combat' club in the area but had also been suffering from a decline in Combat attendance for several years. The reasons for the decline were varied but the biggest factor was lack of an available, durable, attractive, easy to build and fly airplane.

"David 'MiG Man' Drowns of Palomar resurrected the Dave West designed MiG and adapted it to SSC [Slow Survivable Combat] specifications, drew up plans, made templates and had a great flying airplane for Combat.

"Slowly other club members had picked up on this airplane and were making their own. The biggest problem was a lot of people wanted one but lacked the skills, time or ability to build one from scratch.

"Wanting to grow Combat and assist new pilots in building a MiG, the idea of a build party was brought up and before you know it the MiG Build-a-Thon was launched. The first few build parties were a marathon, as all the parts had to be traced from tattered templates, cut by hand, drilled, and glued before the actual assembly could begin.

"The preparation process normally lasted from early morning to lunch time, the builds were ending somewhere around 9:00 pm, additional builds were sometimes required to finish the airplanes. During the builds Mr. Drowns would build one for an example and then that airframe would become a raffle prize at the next contest. This quickly became the most popular prize of the raffle.

"Richard Martin Jr., a budding Combat pilot and MiG raffle winner, saw that having to cut out all the parts first is the biggest obstacle in the build parties. Richard's family owns Tri-M-Co, a metal fabricating shop, and he offered to donate the use of his big CNC laser cutting machine to cut out all the Coroplast and wood for the build. The original templates were converted to CAD drawings and the plans were refined to reduce build time and increase durability and performance.

"With the new CAD files loaded and a few tweaks to a machine that normally cuts one inch thick plate-steel, the Palomar build parties were kicked into high gear. What was taking half the day of prep time for a few airplanes, now could be done for numerous planes in a few short hours.

"Without Richard's generously donated machine use and pre-cutting parts it would be difficult for a new builder to complete an airframe in one day. The build parties had now become a viable way to get an airplane together in about a day ready to fly for Combat.

"The current build parties are usually scheduled one month before the next Combat event and are set-up for 14 aircraft, both SSC and Open-B versions are available for the builds. Through the support of several local hobby shops that provide a club discount for parts and the countless hours Mr. Drowns spends prepping and putting the kits together one can sign up and build a MiG airframe for the unbelievable price of $40. This price is exactly what it costs in materials; all labor is donated by the dedicated Palomar RC Combat group.

"The build parties are a huge success and the slots go quickly and are heavily attended by enthusiasts interested in Combat. The build parties have grown and are now incorporating Treneff R/C's Battle Axes.

"Todd Melton of Palomar and Andy Erwin of MidCal Spads have been working on new SSC Coroplast designs and have several WWII aircraft like the P-40 Warhawk and the Japanese Zero in prototype flying stages, so there is a constant development of new types of aircraft. The new designs once they are perfected will work their way into the builds.

"With the success of the build parties and through some Combat demonstrations and networking with other local clubs, Combat in California is growing fast. With some basic advertising via flyers to other clubs and posting at local hobby shops, Combat events are becoming the thing to go watch by RC enthusiasts and at any given event there is always a large crowd of spectators.

"What used to be four contests in southern California has now expanded and there have been three contests added to the schedule this year, and next year's schedule will have two more new contests and include three clubs new to Combat. Most of the contests' entries have doubled and currently field at least 10 contestants for Open-B and upwards of 20 for SSC. There is also talk of a 'West Coast Nationals' event.

"The work that has been done by everyone associated with Combat here in California has laid the ground work for keeping Combat popular for years to come. The new enthusiasm has renewed interest in Combat veterans and brought them out from retirement to help steer the growth and pass on their skill and wisdom.

"Combat pilots are once again traveling up to 600 miles to participate in the other Combat events in California. There are numerous father/son teams and a number of young Combat pilots that are almost ready for contests.

"I am excited about the future of Combat locally as I like to think California has become 'the tip of the sword' in promoting and growing RC Combat."

Thank you, Glen, for that great success story. Sharing the fun of aeromodeling in a group at all levels increases participation. Expert building sessions can be as popular as the beginner building sessions.

Introducing different aircraft types is helping maintain modelers' interest. Sharing the success with other clubs is feeding the need that every part of the country should have: to fly RC Combat!

MA

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