Firemen (oz14533)

About this Plan

Firemen. Radio control racer model. Wingspan 41 in, for .25 engines.

Note plan shows three versions of the same design, with minor modifications.

Quote: "Here are The Firemen, three smart aeroplanes designed to get you started. Three distinctive but quite different outlines, all simple to build and all sharing the same basic airframe to keep things competitive.

The Firemen are happy to do any aerobatics you can do but maybe somewhat faster than you're used to doing them!

In the end racing comes down to speed, and speed is dependent on the balance between thrust and drag; so to keep the competition close and exciting, The Rules are written to regulate these critical elements. Thrust we control by an engine and propeller limitation. As for Drag well, for simplicity we can divide this into the effects of three major components. Wing, Fuselage plus tail feathers, and any fixed U/C. Wings are a common 41 inch net span, they all have the same low drag section and almost exactly the same surface area. Fuselages all have similar cross-sectional areas, the tail ends all have the same wetted area and the wheels come off for racing anyway!

Incidentally, if you want to design your own Aeroracer, just stay inside the rules, use some common sense and it will he competitive I assure you! Have a go, you'll be surprised.

Now, for all those expecting a blow-by-blow account of how to build The Firemen - tough! If you've been modelling long enough to be playing this game, then you didn't start yesterday. So just figure it all out from the plan, it's not difficult. All you're going to get from me are some points to watch and a reminder of the old adage 'build in all the lightness as you can'.

Wing: After removing strips of veneer for the 1/4 in U/C plates, tack 80 grade sandpaper to one plate and use this to sand out all the slots before gluing in place.

Utilise the wing-blank cut-offs, one propped up for dihedral, to maintain an accurate alignment when joining the wings.

Bandage the wing join with a 2 in strip of 50-100 gsm fibreglass and resin after fitting the TE and torque rods.

Fuselage: Don't forget to trim the nose of the right-hand side to accommodate the side thrust. Build the lower fuselage upside down on the board with F1 hanging over the edge. To keep everything dead
straight line up all the formers on a bold centreline on the board. Allow to dry before mating to the wing. Spot tack with Cyano, check the alignment then, if ok, fillet glue with Aliphatic. Put in your snakes and build up the upper rear fuselage. Cover the front hatch seating with thin polythene, pin the frame in place then build up the rest of the structure; allow to dry before releasing. Line the front hatch from F1 - F4 with 50 gsm glass cloth or tissue, it will survive the constant handling better that way.

Don't forget the wing/fus fairing, it's there for strength and to reduce interference drag - in fact a full Spitfire type fairing would be even better, but watch the weight!

Finishing: This is where the race can be won or lost! Not at all whether you can produce a superb 'mirror' finish but more a case of 'how little weight can I add'. The underside of the nose and wing root be glassed with 100gsm cloth and resin, just for protection, but if you put the resin on with a Phonecard, you can also scrape all the excess off again!

Radio installation is flexible, there is room for all standard servos, but obviously minis would be lighter. Use ball and ring type clevis's on all flying controls and select them for as little play as possible. Just move things around to achieve a CG position approx. 10mm ahead of that shown. (no farther back - at least not for the first flight). By all means experiment later with the balance point and the control throws, all in that quest for speed.

Flying: The Fireman have no real vices, so speed is all up to your technique. If there's a wind down the strip, maximise ground speed by staying low into wind then going higher downwind. Generally speaking, don't pull too much G in the turns and try not to use big control inputs or all you do is scrub off speed.

Well there you are kiddies, can't get any simpler than this, get whittling. Now well sort out the TOP DOGS from the plain old HOT DOGS!"

Firemen, R/C Model World, October 1998.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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