TELEPHONE: (310) 390-8000

FACSIMILE: (310) 397-0028


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:










Lightweight, Two Cycle Aircraft Engines

by Kimball Anderson

I recently noted in the classifieds section of KITPLANES MAGAZINE an advertisement placed by an engine manufacturer located in my home town. I knew of the existence of the company from articles in our local newspaper, but was unaware that their product line included aircraft engines. A brief visit to the factory garnered the information here presented. The following paragraphs are taken from a press release dated August 1996:

100hp Model 808LI-100

"AMW Cuyuna is an all-new company developing and building the AMW and the Cuyuna line of two-stroke engines in Beaufort, South Carolina. 2 STROKE INTERNATIONAL is the name that has been selected to replace the AMW Cuyuna moniker that has been used while the company addressed more pressing tasks. However, with a new factory, new owners, new management, new state-of-the-art CNC machining centers, and a new vision for the future, it was decided that it was time for a new name.

"2 Stroke International (2si) is the product of a merger between AMW and Cuyuna (pronounced Ki you' nuh, the name of an iron range in Minnesota) which became the AMW Cuyuna Engine Company, Inc., at the beginning of 1995. AMW, Inc., was founded in 1985 and was located in Spartanburg, South Carolina. The Cuyuna Engine Company evolved from the Scorpion Snowmobile Company, and was purchased in 1981, in Crosby, Minnesota. In 1994 investors in Beaufort, South Carolina, built a new factory on seven acres in the Beaufort Industrial Park. All operations from both companies were transferred there in January 1995.

"The new 2si facility has a 35,000 square foot main building containing manufacturing and administration. There are also separate facilities including a test building with dynamometers and test stands for engine development and endurance testing. A new manufacturing control computer system has been installed and is now being used on-line for sales orders, purchasing, and the manufacturing database. It is capable of eventually handling lot control for traceability and statistical process control (SPC).

"The new factory allows the company to do almost all of its own machining, plus all assembly and service. 'This allows control over most of the manufacturing process in Beaufort. This is expected to enhance quality control and allow the company to compete successfully in the world marketplace,' according to company president Jim Davey. 'Our recent contract to supply a lightweight air-cooled version of our two-cylinder 430 aircraft engine to a manufacturer in the Far East is proof of this.' That manufacturer builds remotely-powered aircraft for a Far East military power. 2si has also accepted a large government contract for lightweight 215F engines for military decontamination devices.

"2si is now supplying engines from 7 to 100+ horsepower, 20 to 100 for the aircraft market. They are available configured as air-cooled, fan-cooled and liquid-cooled engines. A new lightweight belt reduction drive has been designed and is available for the single cylinder engines. In addition, two models of gear reduction drives are now available for the higher horsepower two and three cylinder engines.

"2si supplies engines to many industries in addition to aircraft applications. For instance, the Sports Car Club of American (SCCA) Formula 440 class uses a half-liter liquid-cooled engine. Engines are supplied for military decontamination units, marine vehicles, remote-control military aircraft, hovercraft, portable railroad building equipment, and various industrial applications.

"2si engines are flying in a number of small airplanes. The 230/430 product line is flying in a multitude of ultralights and light experimental aircraft. The 540/808 family of engines are installed in a number of experimental class aircraft. These include engines in the aerobatic RANS S-9, S-10, Loehle P51, Avid Catalina Amphibian, Honeybee, Ultrabat, BD6, BD5, Revolution Mini-500, and the 250 mph Lighting Bug."

70hp Model 540L-70

I have included general specifications for the three engines in the product line I feel are most applicable to the KR series of aircraft in the table following the text of this article. The 100hp and 95hp models appear to be fuel injected and carbureted versions, respectively, of the same basic engine, with the fuel injection accounting for the differences in power output and price. The 70hp engine utilizes the same bore and stroke as its more powerful siblings, but makes do with two cylinders instead of three. Standard equipment for all three engines includes mechanical fuel injection or carburetors (one per cylinder), air filters, a complete tuned exhaust system, a 10 amp alternator with voltage regulator, an electric starter, a gearbox reduction available in a variety of ratios, and a prop flange. Standard equipment also includes an ignition system consisting of one self-contained module per spark plug (two per cylinder). Optional equipment includes an automotive-type CDI ignition system and an SAE #1 prop flange.

The 100hp and 95hp engines are, of course, the most interesting powerplants in the lineup, but the 70hp 540L-70 is noteworthy due to its light weight and relatively low price. For approximately US$4,000, you get a brand-new, ready-to-run engine designed for aircraft use, including gear reduction and prop flange. An automotive conversion might be done at a lower cost, but would require more time to get ready for service. And at 102 pounds dressed out, you likely won't be nose-heavy. It might be just what the doctor ordered for a standard KR-2 (or, perhaps, something along the lines of a Dragonfly).

2 Stroke International can be contacted at : 2 Stroke International Phone: 803/846-2167

Beaufort Industrial Park Fax: 803/846-2169

8 Schein Loop

Beaufort, SC 29902


 Specifications     808LI-100          808L-95            540L-70                 

General            100 Horsepower     95 Horsepower      70 Horsepower            
Specifications     Three Cylinder,    Three Cylinder,    Twin Cylinder, Cast      
                   Cast Iron Liners,  Cast Iron Liners,  Iron Liners, Liquid      
                   Liquid Cooled,     Liquid Cooled,     Cooled, Two Stroke,      
                   Two Stroke, Ball,  Two Stroke, Ball,  Ball, Roller & Needle    
                   Roller & Needle    Roller & Needle    Bearings, Reed Valve     
                   Bearings, Reed     Bearings, Reed     Induction                
                   Valve Induction    Valve Induction                             

Standard           Fuel Injection,    Carburetors & Air  Carburetors & Air        
Equipment          150 Watt            Filters, 150      Filters, 150 Watt        
                   Alternator,        Watt Alternator,   Alternator, Voltage      
                   Voltage            Voltage            Regulator, Electric      
                   Regulator,         Regulator,         Starter, Complete        
                   Electric Starter,  Electric Starter,  Exhaust System, Gearbox  
                   Complete Exhaust   Complete Exhaust   Reduction                
                   System, Gearbox    System, Gearbox                             
                   Reduction          Reduction                                   

Bore                75mm               75mm               75mm                    

Stroke              61mm               61mm               61mm                    

Displacement        808cc              808cc              540cc                   

Base Weight         101 lbs            101 lbs            73 lbs                  

Approx. Weight                                                                    
with Standard       130 lbs            130 lbs            102 lbs                 

Fuel Required       92 Octane          92 Octane          92 Octane               

Fuel/Oil Ratio      50:1               50:1               50:1                    

RPM at Max HP       7000 RPM           7000 RPM           7000 RPM                

Engine Alone        $6,588             $5,589             $3,240                  

Engine with                                                                       
Electric Start      $7,463             $6,473             $4,115                  
and Reduction                                                                     



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 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 to 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!


By Micheal Mims

Lets talk a little bit about foam and fiberglass construction, otherwise known as composite construction. This article is meant to be very basic in nature and it is recommended that a complete understanding of working with foam and fiberglass construction be obtained before starting your project. Lets first start with the three basic components that make up the composite sandwich.

1. The Skin can be made of many different types of materials, here are some examples. Fiberglass (e-glass s-glass),

Carbon Fiber, Kevlar, Ceramic.

2. The Core can be made of foam, balsa wood, advanced honeycomb mat etc.. There seems to be something new used everyday as a core in composite construction.

3. The Liquid Material is what bonds it all together. Polyester, Vinylester, Epoxy systems, etc.

SKIN, I will keep this simple and not go into all the materials available to the composite aircraft builder. We are going to talk about fiberglass, after all isn't that what our KRs are built with! Fiberglass itself comes in so many types and styles that it will keep us busy. The two styles of glass you should be able to identify are BID and UNI.

BID is short for Bi-directional, it is the most common glass used on the KR. Bi-directional means just that, the fibers are oriented in two different directions usually at right angles to each other and is almost always applied at a 45 degree angle to the part being made. see drawing Bid comes in many weights. 1.5 oz per square foot to 22oz per square foot.

UNI is short for "you guessed it" Unidirectional, and this means that all of its fibers are oriented in one direction parallel to each other. What all this means to you is that BID has strength in two directions and UNI has strength only in one direction. BID is used in making bulkheads, fuselages, wingskins, etc. and UNI is used in making gear legs, spars, spar caps etc. You may ask why would I use UNI if BIB has strength in two directions? Well ounce for ounce. UNI has more fibers oriented in the direction needed for its application so therefore it is stronger.

CORE, as mentioned before, more and more materials are used as cores everyday. But the most common core is foam. So that's what we are going to talk about. Once again we find that foam comes in many types,

Urethane/polyester foam called Clark foam or Last-a-foam is used in the construction of bulkheads fuel tanks and fuselage / wing skins. It come in various densities and thickness and is completely fuel proof and withstands any type of epoxy. It is semi-ridged and can be bent with heat.

Polystyrene foam is used in the making wing cores. It can be hot-wired and sanded to form various shapes. It is blue in color and is sold in sheets at builder supplies for insulating houses. It is a ridged foam and comes in one density. Polystyrene is NOT fuel proof and polyester resins will melt it, use only epoxies for lay-ups!! Do not build fuel tanks in wings that are constructed of polystyrene! One horror story comes to mind of a header tank with a slow leak that continuously dripped fuel onto the canard, the fuel seeped through the unfinished skin (purposely left unfinished for inspection) and melted away the core. The canard gave way one day and that's all she wrote! The farm was purchased signed sealed and delivered.

Polyurethane foam is the primary foam used in the construction of the KR aircraft. It is a ridged foam and comes in tan or green, it is sometimes used in flower arraignments as a base to push the flowers into. (keep your wife away from your foam pile!) This foam is completely fuel proof but caution needs to be exercised while building with this foam. You should not hot-wire polyurethane because it emits a poisonous gas, also breathing polyurethane dust while sanding is extremely hazardous! WEAR A MASK! Polyurethane carves and sands very easy and is used in making wing tips, wheel pants and wings in the case of the KR! Polyurethane withstands any type of epoxy or adhesive.

LIQUID MATERIAL sometimes called epoxy or resin. Again there are many types of epoxies and resins available on the market. I personally like Safe-t-poxy (now called EZ-poxy) There are two main types to be concerned with, Polyester and Epoxy types.

Polyester resins are the type that are usually cured by adding a few drops MEK peroxide to them. I do not use polyester resins and have a very limited knowledge of them. If you are interested in using them I suggest learning as much as possible before starting your project.

Epoxy systems are the more commonly used liquid material in moldless composite construction. Some examples are Safe-t-poxy, Aero-poxy, DOW 330, West Systems, and Epolite RAE System. Epoxy systems are usually two parts, Resin and Hardener. Mixture ratio varies from 1 to 1 up to 100 to 44. Make sure you check your ratio and mix your epoxy thoroughly and correctly. Sometimes two ratios are mentioned, one by weight and one by volume. Pay attention! Build a scale or by a commercially available epoxy pump. Remember epoxies need to be mixed thoroughly and correctly to obtain the desired strength.

Below are a few simple drawings of the proper way to close out a trailing edge lay-up. Notice there is a good glass to glass edge that is filled over with micro. This is by far the lightest and strongest way I know to build composite trailing edges.

This drawing is just a sample of how the KR wing is built for those of you who haven't ordered your plans yet. For those of you who have plans and are building, keep in mind that the fiberglass skin needs to make direct contact with the wood spar. Any varnish or old epoxy needs to be removed from the spar cap before you apply the skin. You want a fresh wood surface for the skin to adhere to.

Also when sanding down the foam to make the airfoil shape, try not to remove to much foam. This will end up making the spars a high spot which can lead to a sand threw in the spar cap area during final finish and filling. This is one area you don't want to weaken by sanding threw the skin!!! It is much better to leave the spar cap area a little low and fill it with micro AFTER you apply the wing skin.

Well I need to send this to Randy and I apologize for part 1 being so short but this month turned out to be an incredibly busy one for me. I would like to continue in the following months with more information if there is an interest. I would like to cover various lay-up techniques, hot-wiring, etc. Below you will find a simple drawing of how I plan to build my wings, the cores will be hot-wired polystyrene.


By I. No Tell

When calculating the time to build your project, always include about 10% for explanations to your spouse. The following questions can be expected:

Why do we now have a part-gray hall carpet ?

Why is the hall carpet solid?

Where did our black cat go to, and where did the white one come from ?

Why is the cat stuck to the wall?

Why has the cat got newspaper stuck to its paws?

Why is there a meowing coming from inside that box?

Why do I stick to the telephone now ?

Why do I stick to everything now?

How did the electricity bill double this winter ?

Why can't I turn the taps on the laundry sink anymore?

When can I get back my garage (kitchen stools, cutlery, scissors, scales, bedroom cupboard, rotary cutter, sanity, etc.)?

Why is there a white outline of a fuselage on the drive-way?

Why is that beam above my garage door bent?

Why is there a hole in the wooden beam across the garage door?

Do delivery men really have to wake us every other morning?

Do you really need all of this stuff?

Why are there glass fiber offcuts all over the den floor?

When can we go on vacation next?

When can we see you again?

Why are you offering me overalls for Christmas?

Why am I wearing this mask and gloves?

Has there really been a computer error on our savings account?

Have you seen this month's American Express bill?

What is all of this blue stuff in the house?

Why do you have to paint the metal green, it's not very pretty?

Where are you going with the bathroom towel rail?

Why did the lumber yard send you a Christmas card?

Do you really need three feet of books beside your chair?

Why did you buy fifty pairs of rubber gloves from the supermarket?

And of course....You're not really serious about building a plane are you?

Closely followed by....I have found this REALLY nice diamond ring! :-)


By Dirk Rackley's

(Editor's note - This information was compiled by Dirk Rackley. Given the gyrations we all go through to decide

on the "ideal" engine airframe combination, the following will provide you with some hours of dream time while not wasting so much time in the research mode while trying to invent the better mousetrap.)

The data for the certified engines came from Janes; the data on the auto-engine conversions came from the company selling the conversion. Some folks have reported different experiences, noteably certified engines that weigh more than the values given here.

Engine HP Weight(lbs) Comments

Rotax 503 50 85

Great Plains VW 1600CC 55 160

Hirth F23-EP2 60 70

Jabira 60 119

PZL 2A-120 60 129

Rotax 582 63 95 Includes 20 lbs radiator, etc.

Continental A-65 65 173

Limbach L 1800 66 154

Limbach L 1700 66 161

Rotax 618 74 136 Includes 20 lbs radiator, etc.

Great Plains VW 2180CC 75 165

Franklin 225 75 230

Limbach L 2000 80 155

Rotax 912 80 165 Includes 20 lbs radiator, et

Continental C-85 85 207

Limbach L 2400 94 181

Continental C-90 95 207

Great Plains VW 2600CC 96 190

Stratus Subaru EA-81 100 205

Continental O-200 100 220

CAM-100 100 225 Includes 20 lbs radiator, etc

Formula Power C100 104 210

Rotax 914 115 155

Lycoming O-235 115 215

PZL 4A-235 116 226

Hirth F30-FP24 120 101

Continental IO-240 125 250

Continental O-300 145 277

Lycoming O-320-A 150 243

Lycoming O-320-D 160 253

Franklin 335 165 320

Formula Power F170 174 270

Lycoming O-360-A 180 265

Lycoming IO-360-A 200 293

NW Aero Ford V6 200 415

PZL 6A-350 205 330

Continental IO-360 210 350

NW Aero Chevy V6 230 420

Lycoming O-540-B 235 366

Lyoming O-540-E 260 368

Formula Power F260 274 390

Lycoming IO-540-K 300 443

Continental IO-520 300 459

Lycoming IO-720 400 568

Certified Engine Weights and Horsepower

Engine Horsepower Weight

O-200-A 100 190

O-200-B 100 190

O-300-A 145 268

O-300-E 145 268

IO-346 165 297

IO-360-B 210 327

TSIO-360- 210 334

O-470-J 225 381

O-470-R 230 438

O-470-13 235 414

O-470-15 190 405

IO-470-C 250 432

IO-470-D 260 426

IO-470-E 260 461

IO-470-F 260 464

IO-470-V 260 472

TSIO-470-D 260 511

IO-520-L 285 466

O-200-A 100 190

O-200-B 100 220

O-300-A 145 268

O-300-E 145 268

IO-346 165 297

IO-360-B 210 327

TSIO-360-A 210 334

O-470-J 225 381

O-470-R 230 438

O-470-13 225 414

O-470-15 190 405

IO-470-C 250 432

IO-470-D 260 426

IO-470-E 260 461

IO-470-F 260 464

IO-470-V 260 472

TSIO-470-D 260 511

IO-520-L 285 466

O-235-C1B 115 240

Engine Horsepower Weight

O-290-D2C 140 263

O-320-A2B 150 272

O-320-A2C 150 271

O-320-B2C 160 277

O-320-D2A 160 277

O-320-E2A 160 277

IO-320-B1A 160 285

IO-320-C1A 160 294

IO-320-E2A 150 280

O-360-A1D 180 284

O-360-A3A 180 285

IO-360-A1A 200 320

IO-360-B1B 180 295

IMO-360-B1B 225 274

GO-480-B1D 270 432

GO-480-G1D6 295 437

IGO-480-A1B6 295 469

IGSO-480-A1F6 340 498

O-540-A1A5 250 396

O-540-B2B5 235 395

O-540-B4B5 235 395

O-540-B4B5 260 398

IO-540-A1A5 290 437

IO-540-C4B5 250 402

IO-540-D4A5 260 402

IO-540-E1A5 290 437

IO-540-G1A5 290 443

IO-540-J4A5 250 409

IO-540-K1A5 300 470

AEIO-540-L1B5D 300 476

IGO-540-B1C 350 500

IGSO-540-A1D 380 530

IGSO-540-B1A 380 532

TIO-540-A1A 310 535

TIO-541-E1A6 380 632

TIOGO-541-A1A 400 663

IO-720-A1A 400 597

Structural Efficiencies

Paul Lamar assembled this list to compare the overall structural efficiencies of various aircraft. He originally sorted the list by the ratio of the empty weight divided by the gross weight. Another ratio is where "higher is better", so we've calculated the "Payload Percentage." The ratio of useful load vs gross weight. The higher the percentage, the more efficient your aircraft is.



Avid 582 1150 510 640 55%

Pulsar 582 1000 460 540 54%

Murphy 503 850 395 455 53%

Lightning Bug AMW 800 375 425 53%

Pulsar XP 912 1060 510 550 51%

Z. Zodiac 912 1200 580 620 51%

Falconar F-12A 1800 898 902 50%

Cessna 185 3350 1687 1663 49%

Rutan Varieze 1050 535 ` 515 49%

Cozy Mark IV 2050 1050 1000 48%

Wag CUB alike 1400 720 680 48%

Berkut 2000 1035 965 48%

KIS TR-4 2300 1200 1100 47%

Cessna 207 3800 1996 1804 47%

Dragonfly 1150 610 540 46%

Rand KR-2S 980 520 460 46%

BD-5 Zenoah 660 355 305 46%

Velocity 173 RG 2400 1300 1100 45%

Velocity 173 2400 1300 1100 45%

GlasStar 1650 900 750 45%

Murphy O-235 1650 900 750 45%

Grumman Tiger 2400 1311 1089 45%

Lancair IV 3200 1750 1450 45%

Cozy Classic 1750 960 790 45%

Super Emeraude 1545 850 695 44%

Dyke Delta 1950 1080 870 44%

Velocity 2250 1250 1000 44%

Velocity RG 2250 1250 1000 44%

E-Racer 1800 1000 800 44%

KIS TD O-235 1450 812 638 44%

KIS Sup IO-240 1450 820 630 43%

BD-4 2000 1140 860 43%

Express Loadmaster 3200 1825 1375 42%

Lancair ES 2800 1600 1200 42%

Glasair II 2100 1200 900 42%

Avid O-320 1750 1000 750 42%

BD-5 TurboPro 890 510 380 42%

Stallion 3300 1900 1400 42%

Cessna 182 2950 1717 1233 41%

WLAC-1 W.L. 4p 2400 1400 1000 41%

Wittman W1 1425 840 585 41%

Express FT 2850 1700 1150 40%

Mooney 201 2740 1640 1100 40%

Glasair II RG 2200 1325 875 39%

Questair Spirit 1700 1025 675 39%

RV-6 1600 965 635 39%

RV-4 1500 905 595 39%

BD-6 675 410 265 39%

Mustang II 1600 975 625 39%



Helio Super Courier 3400 2080 1320 38%

Highlander 1165 715 450 38%

Acro 1 1222 750 472 38%

P51 11600 7125 4475 38%

Thorp T-18 1500 923 577 38%

Questair Venture 2000 1240 760 38%

GP-4 2000 1240 760 38%

Cessna 150 1600 1000 600 37%

Bonanza V35B 3400 2151 1249 36%

Omega II 2100 1350 750 35%

Falco 1880 1212 668 35%

One Design 1140 740 400 35%

Lancair 320 1685 1095 590 35%

Glassair III 2500 1625 875 35%

Pitts S-1S 1150 750 400 34%

Giles G-200 1150 750 400 34%

Turner T-40A 1600 1050 550 34%

MJ-5 Sirocco 1860 1260 600 32%

Midget Mustang 1000 680 320 32%

RV-3 1100 750 350 31%

BF-109 6090 4180 1910 31%

Eagle II 1578 1125 453 28%

Stewart S51D 2960 2200 760 25%


By Randy Stein

You've seen bits and pieces written about it. Well be forewarned, this is not Uncle Fester's home video. OMEGA PRODUCTIONS is a professional organization. I attended the 1996 Gathering myself, so I have a good sense of the how the event progressed. The video brought back the warm feelings and the sights that I took for granted while there. The quality of the video, sound and content is very, very professional! The background music is well scored and integrates perfectly with the scenes. You get the overall flavor of the event.

First know that it did RAIN on Friday morning. Boy did it rain! I arrived the evening of September 19 and met up with Mike Mims at the Little Rock airport rental car counter. Kind of ironic, since Mike only lives 55 min away in Southern California! We met for the first time in Little Rock. Sounds like a good topic for a Country and Western song… We wandered around Pine Bluff looking for the motel. The fact that we drove right by it on the way into town should have a been a clue that neither Mike The-Bush-Pilot or myself were very good navigators. However, logic did prevail and we eventually did find the Best Western. But not before our aimless wandering in Pine Bluff allowed us to discover there are such things as Drive in Pawnshops and Drive in Liquor Stores. In Southern CA, the only drive anything has "shooting" as part of the sentence. Heck, I even have a photo of a sign allowing LOCOMOTIVE PARKING! Of course we didn't see a railroad track within a mile of the lot - go figure.

I managed to give the nice mature female manager of the Best Western Motel a ration of my charm. Poor Mike was hiding in a corner of the lobby. Was it something I said? Heck, I even had an opportunity to cancel Mark Langford's room before he arrived. The temptation was there, but common sense (a rare occurrence in my case) prevailed, and I bit my tongue. We met up with Mark Lougheed at the motel. Introductions again, since none of us had met, except on KRNet. A dinner foray was our next adventure. Not a recommended activity in Pine Bluff after 8pm. Suffice to say that fresh sea food was not, but the ants dining with us sure did enjoy it. For dessert we went airport hunting. Heck we figured to get a jump on the rest of the guys by sneaking a peak at a KR or two. Do you know the term "roll up the streets after dark?" Well, it was written after a visit to Girder Field past sunset. One plane on a HUGE ramp and almost no lights. Cool place to visit with the right kind of company, but three KR buffoons don't fall into this category. We did manage to wake a sleeping KR camper with our load chatter, so the trip wasn't a total bust. We found out the next day that all of the KRs were safely tucked away in hangers. The ramp stumbling expedition was eventually called off when it was apparent that Tommy Waymack had hidden all of the toys. I'm still trying to guess who warned him we were in town? Oh ya … the KR Video…

As the Video starts out, you get a feeling that Pine Bluff is back to nature. It truly is a beautiful part of the country. Well worth a visit. Les Palmer's KR1S is a work of art. Randy Smith was charged with the pilot duties. Hey, a dirty job, but someone has to do it. Imagine flying a Trigear, Soob powered KR with airconditioning?! 140 kt cruise, self made reduction unit, 858lbs empty. See the photo, upper left at the front of this newsletter.

Bobby Muse's award winning trigear KR2 was on hand. He was interviewed and related his cruise is 158mph. Good footage of his remote oil cooler. He also said he has a light Soob starter, Posa carb, and a removable header tank. His fancy fiberglass wing joint covers are a slick solution. His engine cowl construction is a bit different, it sure made for a strong unit.

Jim Fahn describes his plans built KR2. He discussed how he solved his long leg problem - he is 6'-1". Full electric, radios, 155mph cruise at 3300rpm, fixed tail dragger.

Don Betchan's KR2 is another flavor altogether. He has a flush inboard retracting gear system with full gear doors. The video has some good shots of this system. I suspect I will use this system too. I already have some of the parts and most of the measurements needed to make this system for my KR. Don also has a nice side stick controller with an armrest. Yep, I have those dimension too, along with some photographs. Other items; plans build, Dfly canopy, 1835VW = 150mph. See the photo at the beginning this newsletter, upper right. Don is our host at the '97 KR Gathering. Gotta love a KR driver when he is also the airport manager!

Troy Petteway's KR was a hot topic. I had the opportunity to fly with Troy…WOW, what a fast KR - one of the fastest and cleanests around. Troy flys a biz jet for a living. He told me his KR helps him relax after work. Plans built, Revmaster 2100, Revmaster cowl, 525 empty, superb VFR panel, no electrics, battery GPS & com, 170-180mph solo, 155-160mph with 2, 300+ hours to date.

Robert Muse, Sr, gave a charming interview. He has an original retract KR, cost $4,200 to build, 517lbs..

Max Caulkin was also out and about in his trigear, His bird was for sale.

Tommy Waymack had his brightly painted KR2 on hand. He has been flying it 6 yrs, 1835VW, 400 hours total time.

Martin Roberts was on hand.

Willie Wilson talked about flying his KR in England. He brought a photo of his KR parked under the nose of the Concord! What a shot!

Calvin Campbell discussed his KR2. 2180VW, dual mags, 60hp @ 3100rpm, flaps and trigear.

Dah Diehl's KR2 - the third one build and the oldest flying KR - 20 years of fun. Mark Lougheed got to shoehorn in with Dan for some air fun. Man what a grin on Mark's face when he came back after that flight.

Steve Alderman from CO, gave a tour of his KR2. 12 years old, 1500 hours, now powered by a Cont 0-200 (C85 pistons with an 0-200 crank), 190mph+ cruise. Steve spoke about traveling coast to coast and to the Bahamas.

Steve Bennett (yes THAT Steve Bennett) just recently bought Ken Cottle's KR1½. 2180VW, 130mph @ 3200rpm.

Hey folks, if you have any thoughts about the wing incidence issue, see the Video, then decide. Lots of good high and low speed low level flybys. Some good engine compartment shots too.

Bob sells the Video via mail order. 1:46 hour duration, $25.00 post paid. Check, money order, MC/VISA (with card number and expiration date). Mention KROnline at the time of ordering and Bob has offered donate $5 from each Video toward the costs of the next KR gathering. OMEGA PRODUCTIONS, 932 Lamberton, Grand Rapids. MI 49505 (616) 774-3913.


By Jeff Scott

Once that project that has been growing out in your garage begins to start looking like an airplane, it's about time to start taking the balance of the plane seriously. Weight should be one of the builders primary concerns from the initial concept of building your KR, but the balance of the plane is every bit as critical to performance and flyability as is the overall weight. An initial weight and balance should be done while there are still a number of parts left that can be installed in different locations to affect the balance of the plane. Also a weigh in of the plane at this time can be very beneficial in helping you make those hard decisions about what accessories and gizmos you really want in your plane or if the plane is getting heavy, what extras you can live without.

The plans from Rand Robinson Engineering say that the CG (Center of Gravity) range for the KR is 15 to 35% of the wing cord or 8 to 16 inches aft of the inboard leading edge. According to my calculations, it's actually 7.2 to 16.8 inches aft of the leading edge, but the RR numbers are safe to work with. That range is easy to find, but how are you going to calculate where the CG actually is, or even more important where it's going to be with the plane loaded with pilot and fuel and is ready to fly?

You won't need many tools to do the weight and balance. Just one or preferably two sets of reasonably accurate bathroom scales, a few blocks of wood about the same thickness as the bathroom scales, a plumb bob or reasonable substitute, a friend or two to help lift the plane on and off the scales and a reasonably level driveway or hanger floor to use during the weigh in.

The first step in doing the weight and balance is to decide where your datum point is going to be. The datum is either a real or imaginary point in reference to a known immovable part of the airframe. The datum can range from anywhere in front the plane to anywhere behind it, but typically it is a known part of the airframe such as firewall or a spar. In my case, I chose to use the bottom front of the firewall as the datum for my plane. I chose it because it is a known point that should not change regardless of the modifications that may happen to the plane over the years. It is also an easy place from which you can drop a plumb bob to mark out the measurements on the floor beneath the plane. With my datum selected, it made the 8 to 16 inch range behind the leading edge of the wing 20.44 to 28.44 inches aft of the datum.

The next step is to level the plane into it's normal flight attitude. Since this project has never been off the ground, on my KR, I chose level with the top longeron just behind the front deck as my level flight attitude. With the plane leveled, you will want to use a plumb bob to mark out and measure on the floor the distances in inches from the datum to all the important reference areas. I chose to use the prop hub, oil tank, the proposed battery mount on the firewall (although I left the battery to mount until I knew whether I needed the weight forward or aft), center of the header tank, leading edge of the wings, front of the main spar, center of the axles, center of the wing tanks, baggage area, and tailwheel axle. Some of areas such as the pilot/passenger moment arms will be calculated rather than measured. The measurement from each of these areas to the datum is the moment arm for the load placed at that point and will be used as a multiplier. I used a negative number for any moment arm forward of the datum and a positive number for every moment arm aft of the datum. The weight at any of the points multiplied times the moment arm is the load moment or moment weight of that point on the plane. In my spread sheet, I used moment weight when describing the basic airframe itself, and load moment when describing different loads or proposed loads placed in or on the airframe such as fuel, oil, pilot, baggage, etc.

After the plane is leveled, weigh the plane at each wheel. You will need the weight at each main as well as the weight at the tailwheel (or nosewheel as may be the case). I found that with my scales, the sideways pressure exerted on the scales when the gear was set down on them caused extraordinarily light readings. Although I was pleased with the thought of having a 250 pound KR, I didn't quite believe it! I had to bridge the weight between two scales with a piece of steel to get an accurate reading. Don't forget to subtract the weight of the bridge (in my case 2 lb.) for each reading. Use the extra blocks of wood to keep the plane leveled both fore and aft as well as side to side as you move the scales from wheel to wheel to weigh them individually.

Now that you have the weight of the three gear legs, it's time to add them up to see what your plane weighs so far. This is your plane's current empty weight. In my case it was 610 lb.

Take the weight at each of the three gear legs and multiply them by the moment arm for that gear leg. Remember, if you have a nose wheel, it would have a negative moment arm since it is in front of the datum. Add the three moment weights together and you will have the moment weight(or load moment) of the aircraft. My plane came out with a moment weight of 13063.5 inch lb.

To find the current CG (Center of Gravity) of the plane, take the moment weight calculated above and divide it by the weight of the plane. The answer is the CG measured in inches from the datum. If it is a positive number, the CG would be aft of the datum and if it is a negative number, the CG would be forward from the datum. My plane came out with a CG of 21.42 inches aft of the datum( or in my case aft of the firewall as my datum is the bottom of the firewall). Well within the 20.44 to 28.44 inches aft of datum range, except that the empty CG has little value. What you really want to know is where the CG will be in every possible load configuration in which you may wish to fly.

Of course we don't know quite yet what the pilot/passenger moment arm is. It's difficult to measure since the pilot's weight is distributed all the way from the firewall to the top of the seat back or headrest. The most accurate way to find the pilot's load moment is to calculate it.

I put a normal sized human in the cockpit and had him assume a flying position with his feet on the rudder pedals, his hand on the control stick, and resting comfortably in the pilot's seat. It wasn't hard to find a volunteer for this mission (as long as I let him make airplane noises), but it had to be done with the canopy closed, which can be pretty warm if you're working out in the sun. With the pilot in the cockpit, we weighed all three wheels again and did all the same calculations to come up with a new weight and moment weight (load moment) for the plane. If you subtract the original empty weight from the weight of the plane with the pilot, you should get the weight of the pilot. When you subtract the original empty moment weight of the plane from the new moment weight with the pilot aboard, you will get the load moment for the pilot. Divide the load moment of the pilot by the weight of the pilot and you will have the moment arm for the pilot/passenger seats of your plane. This number should be recorded on your weight and balance data sheet. My plane has a pilot seat moment arm of 42 inches aft of the datum.

Now you can start adding proposed loads to the plane using the moment arms that you measured earlier. These loads could include fuel, oil, baggage, battery, and pilot/passenger. This will give you a more realistic picture of the balance of your plane and help you decide where to mount some items that may not yet be installed. This may also reveal a serious balance condition that may be easily resolved by using mounting blocks behind the engine to move it forward or by mounting items like the ELT, strobe power supply, or battery in a forward or aft location.

I found it to be very convenient to plug these numbers into a computer spreadsheet so I could change to many possible load configurations and have an instant answer to my CG and flying weight, although the same could be done with a pencil and paper.

You will need to do a final weight and balance data sheet before the FAA airworthyness inspection. The procedure is the same as the initial weight and balance except that you won't need to mark off and measure the distances for the moment arms since that was done on the initial weight and balance.

This is a sample from my initial weight and balance spread sheet. A final Weight and Balance data sheet will have to be done before the FAA airworthyness inspection or the first flight.

CAUTION: The values in the Weight and Balance spread sheet for N1213W should not be used for any other aircraft. N1213W is a unique combination of KR-2 and KR-2S parts which makes it's weight and balance spreadsheet completely unique unto itself.

Comments about this article should be sent to Jeff Scott at


By Randy Stein

COPPER STATE WINNERS: The Copper State fly in winners include the two KRs profiled last month in KROnline

Custom Built Wood 1st Place: David Chrtistiansen, Brigham City, Utah; KR-2 N612DC

2nd Place: John T. Holsher, KR-2 Starship

BUILDERS WOES: Charles Hall wrote recently; I'm asking this question for Czech friends who are building a Dragonfly

and are having some administrative problems. To make the Czech version of the FAA happy, my friends must provide the profiles used and have some kind of proof that the craft satisfies FAR 23 -- that's the quote from the Czech authorities. If you could help, I would appreciate it. I have done what I can for them: taken them 5 min. epoxy, had shipments of micro held up by customs who thought they were either drugs or some kind of bizarre chewing gum, and carried the canopy over as checked baggage [Northwest loved that...] but I know nothing about planes and can't help them with technical stuff. (Editor's note: And you thought you had problems…)

EPOXY, GRAPHITE & FIRE: David Parrish wrote recently; To see what graphite would do when burned, I took a piece of runner trimming and put a torch to a small projection. It burned very well. Not the graphite. It just glowed yellow even when subjected to the hottest part of a propane flame. But the Aeropoxy burned with frightening speed and was self sustaining. From this, I'd suggest coating the outside of a graphite manifold with a white fire retardant coating that's sometimes used in place of metal and fiberfax for firewalls. This would have four advantages.

1) If there's an engine fire, the manifold wouldn't be lost until it got hot enough to collapse, giving more time to find a landing spot.

2) The manifold would be a less likely source for a fire and wouldn't feed an existing fire.

3) The white would reflect engine heat, keeping the intake charge cooler and make heat softening of the manifold less likely.

4) If there is any porosity in the layups, the coating should seal it.

DUCT TAPE: Carl Zwanzig: observed…"Duct tape is like the Force. It has a light side, a darkside, and it holds the universe together...."

CLEANING LAMINATIONS: David Parrish wrote in reference to a question about vacuuming & blowing with air and cleaning with water or acetone before a layup; Just about any laminate will have pinholes and I worry about a fairly strong solvent like acetone attacking the underlying foam. I've suggested using denatured alcohol since it's a much milder solvent and evaporates fairly quickly. Water might be okay, but you need to make sure it's totally evaporated before the next layup, since it tends to poison the epoxy reaction.

AMBIENT TEMPERATURE FOR GLASS WORK: David Parrish wrote; As far as I know, cold just slows the reaction down. If it's cold enough, the reaction comes to a near stop, so the layup stays soft until it's warmed enough to start cooking again. I usually try to keep my shop at 60 degF or better when I'm doing layups, and even then layups may take several days to cure enough to be cut or sanded. Heat lamps and small (controlled!) heaters can be a big help. That's with the Hexcel epoxy used in the Velocity. Other epoxies may be even more sensitive to cold. Whatever temperature you build at, the highest temperature the epoxy

sees will determine the highest temperature the epoxy can stand before going soft. Post curing under no loads to 120-140 deg F is a good idea. Close up the completed fuselage with a small forced air heater inside and let is heat soak for a couple of hours. You could do something similar for the wing panels.

RESIN SHELF LIFE: When Rutan started selling the Long-EZ plans, an item in the material list was the entire quantity of epoxy. Instead of buying it in bits and pieces, several people bought most of it at once. Of course, none finished their planes in a year and they still had these gallons of epoxy sitting around. RAF's advice was to keep using the epoxy as long as you got it to cure. No

matter how brown or old, a cure was the criteria for continuing to use the stuff.

OIL DIPSTICK SENSOR: I heard that there is a nice unit that fits in the dip-stick hole in the VW that goes down to the sump area. The "Skinny Dipper" Airborne Electronics, Santa Rosa, CA (707)-542-6053 The major benefit of this unit is said to give oil QUANITY!

ELECTRIC WIRE MARKING: Mark all cables with heat shrink cable markers, such as the following system:

11.013-18 = where 11 is the system number i.e. Radio, transponder etc.

013 is the wire number

18 is the wire size in AWG

While this might seem a bit involved, rest assured that it will be quicker in the long run. This is preferable to working it out on the fly, no pun intended, freezing your backside off in the workshop only to find it doesn't work, or forgeting what you did at the last session It is far better to work it all out first while in front of a log fire…

GENERAL VW INFORMATION: Check out this site: This is a collection of VW and aero writings by Bob Hoover. No not that Bob Hoover. This Bob has been inside VW engines for about 40 years now and has a VW powered homebuilt himself. If you want to better understand VWs, this is a good place to browse. He has written many, many folksy VW engine stories in a down-to-earth style. Each one is an in depth study. Good bedtime reading…

GASOLATOR TIP: You should check how the fittings go into the gascolator- test how much flow the fitting is not allowing to pass and how to correct it. Flow test your fuel delivery system in a max climb attitude on the ground BEFORE you go do it in the air! Flow ratings printed on a box don't warrant your results will be the same. Test your installation.

JABIRU ENGINES: Check out: For those of you who aren't familiar with Jabiru, they are an Austrailian Co. that produce a horizontally opposed, 4cyl, 4stroke, 2200cc, 80hp(3300rpm), direct drive aircraft engine that weighs in around 130lbs! Very well built and complete. I heard of a KR2S being built back in the South East who is using the Jabiru. Unfortunately I don't have a name or contact number. Can anyone help?

SUBARU ENGINE CLASSIFIEDS: Dave Stewart has started a SUBARU only ENGINE and PARTS classified section at his website:


There is an increased level of interest and discussion on KRNET in regards to archives, builders association, newsletter, etc. Almost any dialog is healthy. These are all topics that should be scrutinized and discussed. We have a tremendous and diverse well of talent that continues to grow daily. I, for one, am most proud of the continued civility that has grown to be the standard for KRNET. All who participate on the KR forum are to be congratulated. The information flow is most gratifying. The issues of saving, archiving and disseminating the growing wealth of information will need some serious consideration soon. I'm not sure of what or how this will be accomplished, however, there have been many excellent ideas advanced recently. Without formal consideration and commitment by some of us, the discussion could (and likely would) go on for a long time with no logical closure. Understand that there will never, nor should there be, full agreement on most of these issues. Consensus is the keyword. Diversity is what keeps the group alive and vibrant. Over the next month or two we need dialog to continue in directions that will create results. Us KRNETheads have done more in 1996 than almost any KR group can ever claim since Ernest Koppe bowed out. As any body of water can attest to, there needs to be flow in AND out to continue as a living entity. I foresee 1997 as a watershed year. I suspect we will get all of our oars in the correct position to grow the KR community to new levels.

As the months tick away, I see the 1997 Gathering on the horizon. Are you planning to attend? Don Betchan has volunteered to host this years gathering. He has a recently improved airport, and since he is the manager, we can take over and have it our way. Mark your calendar and plan to be there - September 19-21 1997. What type of events and happenings would you like to see? What vendors and seminars would be appropriate? I'm collecting thoughts and ideas as they come in. Do your part and toss some out too. You can post them on KRNET or Email me direct Some assistance and participation at the event would be appreciated. Early on commitments (volunteers) will make for an easier time in drawing in vendors support and participation. We want to increase the number of KR people who may be outside of our computer world. It is a slow process, but I see a steady growth of newcomers. KRNET now has over 90 subscribers! A far cry from the beginning of 1997 when KRNET was born.

Articles, articles, articles…my continuing mantra. Everyone has good ideas, thoughts and questions. You don't have to be an English major or a published author to participate. Large or small, anything you have to contribute is appreciated and worthwhile. Got ideas, but don't know how to go about making it happen? Email me direct and I'll give you your very own how to sermon. If you derive any enjoyment or gain any knowledge from the past issues of this rag, you have an obligation to contribute something back. RMS