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F2D News – 7 December 2003
Mark Rudner

Well I hope by the time you get this everyone is done digging out from this storm. As my first taste of snow, I must say it looks kind of neat, but it’s not quite cool as the movies made it seem. My little orphan Annie secret decoder ring and Red Rider B.B. gun should be showing up any day now…

One recent development of which you may or may not be aware, is that Neil has added an FAI News section to the webpage. In this section, you can find links to my previous columns, as well as other useful information as I get the time to prepare things. Currently, the most important supplemental document on the page is a copy of the official FAI Sporting Code, which contains the full set of rules for F2D combat. These are a must-read for anyone thinking about getting into the event. Although at first it might look like there are a lot of rules, the real situation is really not that bad since nearly everything is derived from two guiding principles – safety and fairness. Additionally, the page has a link to the slides I used in a talk that I gave to the Charles River RC club a few weeks ago. The talk was a broad overview of FAI combat, with a focus on history, equipment, and procedural matters. I’ve also collected together a lot of good photos from my archives and from the internet, so if you have access to the website you might want to check it out.

As promised last month, the remainder of my column this month will focus on the equipment of F2D. The detailed legislated specifications are in the Sporting Code (available on the website), but I’ll give a more practical description here. The first thing is, as most are probably aware, the maximum engine displacement is 2.5 cc (0.15 cu. in.). There is no speed-limit as there is in GX combat. There are, however, several restrictions on equipment that in one way or another do limit the potential power output of the engines. Many of these you will not have to worry about explicitly, since they are built in to FAI combat engines from the start. There is a maximum venturi diameter of 4 mm, which cannot be exceeded. Mufflers are also required, and must meet certain size specifications. Most importantly, the outlet diameter is limited to 8mm maximum, and there can be no bell-shaped flare extending out beyond the point where the outlet hits 8 mm. All recently produced mufflers should conform to this rule about flaring the outlet. You should always be careful in handling your equipment though to be sure that these openings do not get distorted (i.e. never try to drill out the venturi for any reason). Last, everyone is required to run fuel which is 10% nitro, 20% castor oil, and 70% methanol. Ordinarily, this fuel is to be supplied by the contest directors and all contestants must draw from the same container just prior to their matches. Also note that these engines run on bladders, not hard tanks.

In the next month or so, I will be importing a batch of Cyclon PC6 engines to distribute around to those who are interested. In my opinion, these are very high quality engines at a more reasonable price than some engines, and should really give you the most bang for your buck. Brian Stats recently acquired one from Mike Willcox, and it seemed to be running well for him at our FAI contest in October. Other strong engines that are available are Fora engines, available from George Cleveland or directly from Stas Chornyy, Redko engines, Zorro engine, available from Jari Valo in Finland, and AKM engines possibly available through Andrey Nadein from Pennsylvania. You can’t really go wrong with any of these engines, but for someone new to the event I think the Cyclons may be the easiest to work with.

One thing I’d like to stress is that once you start building up a fleet, it’s important to try to keep your equipment as uniform as possible. If you have one each of several types of engines and different models to fit each one, you’ll quickly find yourself in a needlessly stressful situation at the competition trying to figure out what goes where and which model is the best to fly for a particular match. If instead you have 3 or 4 identical engines and a fleet of identical models, then it will make no difference what engine goes where and which model you use against which opponent. The net effect is that you can spend more time concentrating on your flying and less time worrying about your equipment.

One other important thing I should discuss is flying lines. You may have heard that FAI models fly on “52 foot” lines. This is not quite correct. The actual dimensions are metric (and worked out such that 10 laps is 1 kilometer). Please refer to last month’s column or the links on the webpage to see actual dimensions your lines must satisfy. It’s a tight tolerance, so always double and triple check yourself before making a batch of lines. There’s nothing more frustrating than showing up at a contest with 10 brand new sets of lines that all turn out to be half an inch too short. Additionally, the minimum diameter of the lines is 0.0152”, which is bigger than just 0.015”. As a result, only some spools of American lines claiming to be 0.015” will actually be legal. On this point, however, the European/Russian type of flying line (usually gold/brown color, and 4 strands) is much sturdier than the 7-strand stainless steel stuff we can get over here. If you’re planning on doing any kind of FAI combat, I highly suggest getting some of these lines. Bulk line and ready-made sets are available from sources such as Mejzlik Modellbau, or from Stanislav Chornyy, 2000 World Champion.

Speaking of Chornyy’s wares, Victor Stamov of the Ukraine will start exporting Chornyy’s combat equipment to the US soon. To help make things run smoother in this part of the country, I will try to coordinate orders from the US so that we can all save on shipping, etc. A partial list of things he has for sale is available at his web site. If you’re interested in getting more information about any of these items, seeing pictures, or placing an order let me know and I will do my best to help set it up. I will be placing an order in the next few weeks, so if you’re interested in getting anything on the same shipment let me know and we’ll try to work it in.

Last, a few comments about models. As you will quickly notice, FAI combat models pretty much all have the same distinctive style. There is an extremely tough baseball bat-like leading edge, with open bays (usually 3 ribs per side) behind, and the stab right on the trailing edge. This design has evolved over the years, and there are reasons for nearly everything that goes into the model. For instance, models with tail-booms/ long fuselages have gone out of fashion, because this extra piece is little more than a liability in a match; a broken boom can cause you to stay on the ground when you could otherwise still be in the air scoring points. In FAI combat, one point is deducted from your score for each second you sit on the ground, and one point is added for each point you’re in the air. At 100 points per cut, this means a mere 50 seconds on the ground already puts you down 1 cut.

If you decide to build your own design of FAI models, I suggest taking a good look at what’s already out there first to avoid having to redesign the wheel. An adjustable mounting system is a must to allow yourself the ability to adjust the CG, and it’s also not a bad idea to try to stick with the strong leading edge/open trailing edge type of format. Of course you should never let history stifle your creativity, so I encourage you all try out any ideas you may have. In next month’s column, I’ll try to go into more detail about the various aspects of standard FAI models and he wide variety of trim adjustments they allow to enable anyone to set them up exactly to his/her liking. In the meantime, you may want to ask Santa for a couple engines or a spool of bulk line.

If you have any questions or comments, please email Mark at rudner@mit.edu