Tri-R Technologies  TR-4


This Builder's Manual is NOT the official manual as published by TRI-R Technologies.  


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CRUISER is an aircraft that you will use daily for sport flying and utilitarian cross country trips. It deserves a gentleman’s cockpit… well upholstered and technically well equipped. If you cannot afford to complete the aircraft when you first build and fly it, proceed in such a manner that future updates can bring the aircraft up to you fullest expectations.

The design concept and layout for any cockpit should be well thought out and must be as close to modern aircraft standards as possible. This is an area of detailing that deserves a builder’s patient attention and creativity. Take pride in this job.

The instrument panel and complete aircraft electrical system must be planned together. The number and type of switches and circuit breakers on the panel are dictated by the electrical system. In return the electrical system must support the instrument and radio systems. Read all of this plus portions of other appropriate literature before beginning.

Do to the complexity of the subject matter discussed herein this text does not give detailed instructions or try to comprehensively cover subjects dealt with thoroughly elsewhere. Builders are encouraged to obtain additional texts. Various suppliers catalogues are also invaluable not just as a source of parts bust also as a source of user information.

Suggested publications include:

"Sport plane Construction Techniques" by Tony Bingelis

"Firewall Forward" by Tony Bingelis


Aircraft Spruce and Specialty Catalogue

Wag Aero Catalogue


You may not be able to determine the necessary location of the battery pending weight and balance measurements. Therefore it may be necessary to install it late in the building process. Rather than wait until the ship is painted you can make a preliminary weighing anytime after assembly of the wing to the fuselage. The battery can be temporarily mounted based on that data but do not make the installation permanent pending final weighing. (See Weight and Balance section for details and designer’s limits.)

If the battery is to be located inside the fuselage safety consideration dictate use of a battery box. New boxes are available from aviation suppliers and good used ones are available from wrecked aircraft.

The battery or its box must be attached securely to primary airframe components that can withstand the structural loads imposed by a heavy object during crash conditions. A vent tube must be routed overboard.

When attaching the battery forward of the firewall use either a commercially available battery mount or build your own. To make your own just cut and bend a piece of 1 inch aluminum angle and bolt it to the firewall to form a vertical positioning tray slightly larger in width than the battery. Then make up some long threaded rods and a horizontal cross-strap. The threaded rods go through the battery box verticals and hold the strap and battery securely to the fire wall.


While building the fuselage you fabricated and installed the standard instrument panel or installed a pre-molded custom deluxe panel. The mount holes for instruments, radios, switches and circuit breakers could have been made prior to or after installation. There are two ways to mount the instruments to the standard panel. If you are mounting a 3 1/8’ instrument make a 3 inch hole with a hole saw. Open this to 3 1/8 with a file. Next remove the rear laminate and honey comb core so that the instrument can be mounted to the face laminate from the back. Add close-out glass from the back side of each hole to strengthen the installation.

An alternate method is to take a saber saw and cut out large areas of the panel on the right and left sides where the instruments will go. Make two aluminum plates, one for the right side and one for the left side of the panel. Use a fly cutter to make the round instrument holes in the aluminum and mount the gages on the plates. These plates are then bolted to the main panel or suspended with shock mounts. See cross-section and panel layout drawings.

Before deciding exactly how to arrange your instruments, radios, switches and engine controls, study a modern certified aircraft. The Cessna 152 is ideal because it adheres to international standards and was developed so that students would be properly trained. A person acquainted with such a layout can step into any modern certified aircraft and immediately scan the instruments without confusion.

Placement philosophy for side-by-side aircraft like Cruiser is to locate the primary flight instruments in front of the pilot. The engine instruments go on the right side of the panel. Radios are stacked in the center.

The drawings on the next page show suggested panel layouts for a KIS aircraft. Potential layouts for both the standard and custom deluxe panels are illustrated. The two illustrated panels are similar in layout except on the right side where the custom panel sculpturing causes some placement differences.

Examining the drawings you will see that the hypothetical standard panel lacks some expensive equipment shown on the custom panel. The gyro horizon and LORAN have been omitted but the spacing is unchanged so that the equipment can be added later.

Builder’s using the custom deluxe ready-made instrument panel may mount their instruments directly from behind. Note that all the instruments on the left side of the illustrated standard panel are shown mounted on a separate metal panel (.090 aluminum abut 8 X 12 inches); those on the right are mounted on a smaller panel. These panels can be shock mounted with special rubber mounts if so desired.

Switches are best grouped together. With the exception of the magneto and start switches all others can often go together in a line. The use of unitized switch/circuit breakers will simplify and improve your installation.

Most of us at times forget and leave the master switch on when leaving the aircraft. The result is frustration and a damaged battery. An on-off key lock such as those sold in automobile stores like Pep Boys will help minimize this problem when installed as a master switch in the solenoid circuit. Consider using such a switch.

Use new, near new, or yellow-tagged instruments and radios only. It is unacceptable to build a beautiful new aircraft and put old looking and possibly unserviceable equipment in it.

Many builder’s get their instruments and engine at the same time by buying a "totaled" aircraft. Unfortunate this often leaves the builder with ancient looking gages. If this is your situation find a copy of Trade A Plane and investigate having the instruments rebuilt before installation. You want your panel to look and function like a new airplane.


In view of the fact that Cruiser is a cross country aircraft you will do well to spend some dollars on radios. A hand-held communications transceiver may be adequate to get you in the air but sooner or later you will need adequate electronics. Your particular needs and desires will dictate exactly what to install. Thoughts pertinent in the United States on the matter follow:

taking over. The VORs are still good to fall back for navigation tasks. VOR’s are

also useful when duplexing with FAA in route FAA Flight Service Stations. The

Narco MK 12D and King/Bendix KX155 will remain effective utilitarian radios for

years to come. Regardless of whether selecting COM-only or Nav/COM type units

try to get one with flip-flop frequency handling.

Radios are normally not just cantilevered from the panel. Their trays are supported at the back end. Mechanical support can come from brackets attached to the single intercostal. If this doesn’t work out add another intercostal on the right side of the radio stack and appropriate cross pieces.


The two Bingelis manuals listed at the beginning of this section are essential reading before starting electrical wiring. Read these and/or have an expert aviation electrician or experienced home builder help.

Plan… think… plan! First make a complete schematic. Don’t worry if your drawing is rough looking. Determine what wire sizes will be required for the various sub-circuits. Calculate the fuse or circuit breaker capacities at the same time.

Part of the planning and preparation includes thinking our how the wiring will be bundled and routed. Military type wiring bundles should be routed along rigid paths where they can be neatly laced and lashed down to the airframe instrument panel every few inches. Be sure that noise carrying from the magnetos are routed as clear as possible of other wiring.

Wiring (and things like the fuel primer line) coming through the firewall must not be suspended in air to get the instrument panel. Route them across the firewall and then aft along the fuselage side or aft along the intercostal. The wiring can thus be mechanically supported or constrained all the way.

If possible provide extra breakers, switches and routed wires to places where power will be required later. For example, you may know that you will add radios in the panel or even strobe lights in the wing tips.

Solderless crimp fittings are essential. The best are the aviation type fittings and matches ratchet crimp tool that create a double crimp. One crimp holds the wire mechanically at the insulation; the other makes the metal-to-metal electrical joint. If these fittings are nor available to you then use standard home hardware crimp fittings it is a good idea to support and insulate all terminations with shrink tubing. Shrink tubing support is a must if you elect to solder fittings in lieu of crimping.




Mark the function of all switches and circuit breakers. Engraved plaques or use decals to mark the panel functions as shown on the lower panel in the drawing. Use special colored decals to mark the engine and flight gages to indicate service limitations. Cruiser limitations such as design airspeeds are specified in the Table of Specifications.