Minuteman II (oz10719)

About this Plan

Minuteman II. Control line FAI team racer model. Wingspan 38 in, wing area 196 sq in. Super Tigre 150 engine shown. Winner of the 1964 US Nats.

Quote: "In the past few years, a new control-line event is slowly gaining popularity in the United States. The event is FAI class team racing. This is basically an event derived from American 'B' team racing but tailored to European engine sizes. No other event we have flown has been as satisfying or challenging as FAI team racing. We have gained a tremendous amount of respect from the European modeler by trying to compete against him.

In this two-part article, we will try to explain some things we hope will be of help to those interested. So, if you are ready, turn the needle valve in a little, adjust the compression lever, and away, we go.

ENGINES: In FAI team race the diesel engine is known to give a better performance than glow engines. This may change in the future but for now the diesel is King.

Regarding the choice of an engine for racing, there are three standard engines. The ETA .15 Mk. II; the Oliver Tiger Mk III Modified; and the Super Tigre 15D. There are many other 15 diesels available which can be used but they have not been proven to the extent that these three have.

While the diesel removes the problems encountered with the glow plug, it has its own Pandora's Box of traits. Since all the engines noted have variable compression, a new and very critical adjustment is added. The combination of needle valve and compression setting allow an extremely wide range of running. The best setting for team racing is the one with the lowest compression setting with the leanest needle valve. This will give you maximum speed and economy.

While we are still somewhat new with diesels, there are certain traits which we have noticed. The best way to ruin an engine is to overcompress it. This will tend to 'beat out' bearings and 'tear up' connecting rods. Approach the optimum compression setting from the undercompressed side. Occasionally 'over compressed' settings are inevitable but care should be taken to avoid them.

A large propeller will require less compression than a small one for correct running. This is important when you use a warm-up propeller (see section on props in part two).

When starting a cold diesel, the compression screw should be turned in (increased) approximately 1/4 of a turn from the running position. As soon as the engine starts and sounds like it is warming up, back the compression off to the proper setting. This procedure should only be used when the engine is dead cold and not for every start. The needle valve should also be opened approximately half turn.

We must mention here that a diesel which is under compressed and rich during starting is the meanest thing on earth. It will beat you to death no matter how you flip it. Once the settings are in the ball park, the engine will start very quickly and easily. When the engines are warm, starting is very easy. The propeller should be 'batted' rather than flipped for best starting.

As yet we have found no way to hop-up the diesels. Things which help glow engines do not seem to help these engines. As a result, all the engines we have run are completely stock except for the needle valves and venturi restrictor. A typical change is squaring the needle valve body. Also changing to different makes of valves. You will be surprised at the results. Another im-portant part is a ratchet. This can be made by cutting off the end of a Veco needle and soldering it on the Super Tigre needle. You will have to cut off half of the standard Veco needle clip in order to fit it in the airplane. Don't be afraid to experiment.

The modification to the Super Tigre venturi and needle valve which we make are shown in the illustrations. Replacing the Eta needle valve with Dooling split valve appears to help the consistency of this engine. Ken Long of England also makes a special needle valve assembly for the Eta, called a 'Range Bar.'

No one has yet proven which is the best engine for FAI team racing. The ingenuity and patience of the person running the engine more than any other factor will effect the level of performance. We in the USA are at a slight disadvantage due to lack of diesel running experience. You probably can't purchase any of the engines we've been talking about at your local hobby shop. Listed below are the places where we purchase ours.

AIRPLANE: One of the nicer things about FAI TR is the airplane. While the FAI TR has restrictions, there is no need to limit your thinking on appearance. Three of our attempts are shown in the photo. The basic limitations are 186 sq inches of area in the wing and tail, a minimum fuselage height of 3.97 in and 2 in minimum wide. The cross section of the fuselage at point of maximum height and width should be at least 6.06 sq in. For the exact wording and more complete details you should consult the AMA or FAI rule book.

The requirements of a good FAI plane are the same as those of a good rat racer but to a higher degree of refinement (see June/July '62 MAN for rat racer specs). The lower torgue of a 15 engine plus the large size of a FAI TR simplify the torque problems during takeoffs. This will eliminate the use of engine offset for take-off as on the Rat.

The one point which has placed the FAI TR apart from almost all of the other control-liners we've built is that streamlining is important. On rat racers we've built, streamlining has provided no particular advantage or given any performance increase. However, with the small engine and large FAI airplane any improvement in drag reduction has shown up as increased speed or economy. Our #5 airplane gained 4 to 6 laps in fuel economy when the airplane was rubbed out. Its finish wasn't good at the start but more paint rubbed out gave a fine smooth finish and better performance. We are sure that the change in performance came from the paint as nothing was changed and the engine had no more running on it between tests.

All our ships have wings of 3/8 in balsa. The theoretical advantage of a thin wing, 1/4 in or less, are lost because of twisting and fluttering in flight. Here again this has been our experience, you may find out differently.

The use of a 3/16 in thick stab and elevator is almost a must because of the large size, 40 sq in or more, of the surfaces..."

Direct submission to Outerzone.

Update 19/12/2018: Added article, thanks to RFJ.

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