KROnline NEWSLETTER

Volume I Issue IV November 1996

The KROnline Newsletter is intended to serve as a conduit for information and building ideas about the KR family of experimental aircraft. It is meant to share the knowledge that has been hard won by those who have gone before us. Education is the ornerstone to a quality built KR.

The article submissions each month are from KR builders and suppliers. Opinions express are solely those of the individual authors and not of KROnline. Any ideas or techniques discussed are to be duplicated and used at the sole risk of the experimental aircraft builder. KROnline does not endorse or warrant any certain outcomes.

Rand Robinson Engineering is in no way affiliated with KROnline and as such, does not formally endorse any information published in KROnline.

In this issue:

TWO STROKE INTERNATIONAL

DESIGNING YOUR PANEL FOR MAINT.

BASIC COMPOSITE CONSTRUCTION - I

BUILDING TIME CALCULATIONS

ENGINE WEIGHTS AND HORSEPOWER

KR GATHERING 1996 VIDEO & FUN

THAT INITIAL WEIGHT & BALANCE

KR TIDBITS

DESIGNING YOUR PANEL FOR MAINTENANCE

By: Bob Lee

This article has been written to give you a slightly different point of view than the instrument panel article in the last issue; consider designing for maintenance. The idea is quite simple really, all you have to do is figure out how to work on the back and the front of the instrument panel without being a contortionist. After watching a friend spend hours trying to get to a nut on the back of his panel I vowed never to have that problem. N52BL's panel was build off of the airplane. I assembled the components and wired them in the comfort and cleanliness of my den. As the panel was assembled, wire runs were measured and sufficient lengths of wire was installed on the instrument panel to ultimately connect to the respective component in the airplane. To facilitate this, absolutely EVERYTHING coming off the panel was routed through a bundle against the right sidewall just behind the fuel tank. This routing of the wires, cables, and tubes allows the instrument panel to be rotated 90 degrees and placed across the passenger seat giving full access to the back and front of the panel.

Building the panel with maintenance in mind allowed me to be extremely tight in the placement of devices. This maximized the utilization of the panel area. The dimensions for instrument layouts have been dealt with very well by Tony Bengalis in his books so I won't cover it here. My recommendation is that you build the panel in cardboard to allow you to make the decisions that will be needed to form your panel. Once you have the layout just as you would like it to be you can write out an equipment list for your instrumentation and avionics. Don't bother building the panel until you have purchased at least half of the components. The price/wants decisions that you ultimately make will change the layout of the panel. It is indeed an iterative process of laying out the panel based on what you want and reorganizing it based on what you've been able to afford. One other consideration is the depth of the cutout into the fuel tank for the radio rack and instrument clearance. In my case I made one cutout from the right of the radio rack to the left of the artificial horizon and from the bottom of the panel to the top of the fuel tank. If you use some older electric gyros as I did, you will note that they are almost as deep as the radio rack and need some extra depth behind the panel. If you're going strictly VFR or you can find shallow gyros, you could reduce the width of the cutout to just the width of the radio rack. The point here is that your panel layout must be a three dimensional mock-up to insure no surprises when you're building.

The bottom of the panel sits on the top longerons because with my cardboard mock-up the open leg room was very comfortable to me. I choose not to make the panel any lower to give the "illusion of roominess" inside my KR. The top of the panel seems to be too high to many people that have seen it but that too is an illusion. With the plane in the 3 point position and me in the pilot seat, I set a straight edge on the top of the spinner and at my eye level in the cockpit. The height where this line crossed the instrument panel was set as the top of the panel. That way I got the most panel area without interfering with my line of sight vision. The following picture shows that IFR instrumentation can be placed in a KR-2 without too much difficulty.

From left to right across the top: G-meter, airspeed, artificial horizon, altimeter, omni, loran, engine monitor, landing gear indicator lights; Middle row: auto pilot and trim controls, turn and bank, directional gyro, compass, nav/com, engine monitor selector switches; Bottom row: circuit breaker switches, transponder, trim tab location meters, fuel gages. (Since the photo an audio panel and marker beacon lights have been added above the loran)

The panel was build out of a single piece of .065 7075 Aluminum. The sheet is a little too thick and a little to exotic (2024 or 6061 would be fine) but I found a 2' by 4' sheet on a sale table in the fly-mart at Oshkosh for $10.00. It is braced across the back of the panel with two 1-1/2" x 1/8" Aluminum angles riveted to the back of the panel as stiffeners. The lower stiffener is located just above the circuit breakers and the second stiffener is located across the top of the instrument panel. The same angles are used as vertical stiffeners on either side of the radio stack to maintain the structural integrity of the panel through the center. One inch diameter lightening holes were bored in the stiffeners on 1-1/2" centers on both flanges of the angles. To punch the 3-1/8" instrument holes I used an instrument punch. It's a male and female circle die that has a bolt through the center. By drilling the instrument center holes slightly larger than the bolt diameter, you can adjust the punch to be exactly on center for each hole. This is the kind of tool you should buy in a group as each of you will only need it once and it's difficult to wear out tool steel. Make sure you put plenty of grease on the bolt and nut to make the cutting easy. The panel is mounted to the airplane with four shock mounted screws accessible from the front.

If it's easy to work on you will be able to fix it quicker and do more flying!