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CONTACT! ISSUE 89 PAGE 1
PO BOX 1382 Hanford CA 93232-1382 United States of America 559-584-3306 Editor@CONTACTMagazine.com
Volume 15 Number 6 Jul-Aug 2007
Issue #89 MISSION CONTACT! Magazine is published bi-monthly by Aeronautics Education Enterprises (AEE), an Arizona nonprofit corporation, established in 1990 to promote aeronautical education. CONTACT! promotes the experimental development, expansion and exchange of aeronautical concepts, information, and experience. In this corporate age of task specialization many individuals have chosen to seek fresh, unencumbered avenues in the pursuit of improvements in aircraft and powerplants. In so doing, they have revitalized the progress of aeronautical design, particularly in the general aviation area. Flight efficiency improvements, in terms of operating costs as well as airframe drag, have come from these efforts. We fully expect that such individual efforts will continue and that they will provide additional incentives for the advancement of aeronautics. EDITORIAL POLICY CONTACT! pages are open to the publication of these individual efforts. Views expressed are exclusively those of the individual authors. Experimenters are encouraged to submit articles and photos of their work. Materials exclusive to CONTACT! are welcome but are returnable only if accompanied by return postage. Every effort will be made to balance articles reporting on commercial developments. Commercial advertising is not accepted. All rights with respect to reproduction, are reserved. Nothing whole or in part may be reproduced without the permission of the publisher. SUBSCRIPTIONS Six issue subscription in U.S. funds is $24.00 for USA, $28.00 for Canada and Mexico, $40.00 for overseas air orders. CONTACT! is mailed to U.S. addresses at nonprofit organization rates mid January, March, May, July, September and November. Please allow time for processing and delivery of first issue from time of order. ADDRESS CHANGES / RENEWALS The last line of your label contains the number of your last issue. Please check label for correctness. This magazine does not forward. Please notify us of your date of address change consistent with our bimonthly mailing dates to avoid missing any issues. COPYRIGHT 2007 BY AEE, Inc.
Another mile- stone for us. This is the last issue of Volume 15. We took over with the beginning of Volume 13 and have managed to keep it together for 18 issues in a row. And with that, many of you are looking at the last issue of your subscription. Please check your mailing label to verify when your subscription ends. It’s very important to us that you renew as soon as you can if you are expired or close to being expired. We don’t have the resources nor the desire to bombard you with renewal notices like other publications, so please help us. Multiple years and gift subscriptions for your friends and family are much appreciated. Incomplete articles: In a recent
editorial, I asked our readers how they felt about reading articles about incomplete projects or products still in development. I received several responses, but not a single one was negative. Everyone who responded was very positive that they would indeed like to read about other people’s projects. So with this issue, specifically on page 12, we showcase Mark Steile’s Lancair ES. Just today I received a Continued on page 21
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Chevy Powered Wheeler Express. Bud Warren of Geared Drives introduces us to his geared redrive, as proven with his beautifully crafted Wheeler Express. Former CONTACT! Magazine editor and publisher Mick Myal found this story for us at SnF 2007 and through a collaborative effort with Bud’s daughter Phyllis Ridings-Murawski, they bring us this article.
12 Three-Rotor Lancair ES. A project report on a plane that’s about to take its first flight. We’ll certainly be following up with this one. By Mark R. Steitle 14 The Vari-Prop by Pitch Control Systems, L.L.C. We couldn’t be more pleased to announce the union between the fine people at Vari-Prop and Paul Lipps, the creator of the Elippse Propeller. We now have a commercially available version of the Elippse prop, and best of all, it’s constant-speed. By John P. Moyle and Patrick Panzera 20 Traffic Detector Report. An unsolicited report on a traffic avoidance device, the Traffic-Watch ATD-300, installed after a close encounter with a Gulfstream pilot with his head “up and locked”. by Steve Makish 21 CarterCopter. The people at Carter announce their 6-7 place turboprop, “Next Generation Business Air Vehicle" (BAV) for true point-to-point travel. 22 How fast are you really going? Revisited Part II, reprinted from issue #88.5. By Paul Lipps 24 Paul’s Updates My Plane Since Issue #77; Belleville Washers For Prop Retention: Reno Successes: Vari-Prop, reprinted from issue #88.5. By Paul Lipps On the cover: Bud Warren’s Wheeler Express. Photo by EddiesAirshots.com.
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By Mick Myal and Phyllis Ridings-Murawski Bud Warren Geared Drives LLC 1510 South 3rd Conroe TX 77301 (936) 827-5126 www.GearedDrives.com Bud@GearedDrives.com Bud Warren built his first motor at age thirteen and since then has amassed an enviable record in the automobile racing community. His passion for speed was expressed by building and racing funny cars, race boats and most anything else with wheels. His successful Warren Machine Shop business supported these fun activities that grew with time. AirAll photos courtesy of Bud Warren, unless otherwise noted. planes appeared as a means of As time drew near to install the engine in the airframe, keeping his hands on the business while increasing Bud found that existing redrive solutions were disaphis racing presence on the West Coast. But there is pointing to him. His previous experience with chain and much more to Bud’s credit: safety inspector for SEbelt driven racecar components did not leave him with a MA (Specialty Equipment Market Association); malot of confidence, so the idea of using a chain or belt drivchine work on the NASA Gemini program; Commemen PSRU did not satisfy him. It was obvious to Bud that orative Air Force aircraft restorer and pilot; licensed the weak link in automotive conversions was within the A&P mechanic. Bud began flight lessons in 1980. He redrive unit itself; the technology needed to efficiently has owned three Mooneys over time but around and safely transfer torque to the propeller. This concept 1990, concerns over potential engine failures set him to the task of developing a redrive “transmission” brought him to consider an automotive conversion. that would allow his Chevy engine to function in an airHis Chevy powered Wheeler Express features his craft in exactly the same way it was built to function in a unique design of a gear-driven prop speed reduction car and at the same time reduce RPM to the propeller to unit (PSRU) which he refers to as a “transmission”. achieve the best rate for efficient flight. This work culmi~Mick Myal nated in the invention of his gear-driven, fully automatic centrifugal clutch, which is the basis for success with his geared redrive. After several years, Bud accumulated a following of local homebuilders who had been watching his progress and they began to encourage him to share this redrive with others. Bud eventually agreed to the commitment and began to offer his redrive to the experimental aircraft world. The original test bed aircraft, a Wheeler Express now owned by Bud (seen on the cover of this issue and in the photos throughout this article), can be seen at most airshows, still powered by his original Chevrolet engine and prototype Geared Drive™ unit. HOW IT ALL STARTED In 1992, a friend approached Bud about the possibility of PHILOSOPHY using a small block Chevrolet in his all composite four place “Wheeler Express” experimental aircraft. Bud was Operating an aircraft engine at an RPM that gives the fascinated, saw a challenge, and set out to design and highest amount of torque while not over-speeding the assemble an engine and redrive combination that would propeller is preferred. Horsepower is the product of be safe, dependable, and affordable. As a certified A&P torque and RPM and since conventional propellers are mechanic and former National Hot Rod Association designed for maximum efficiency in the area of 2100(NHRA) top fuel dragster builder and driver, he was in2500 RPM, there is little need nor benefit to turning the trigued with the idea that an automobile engine could be propeller any faster even if it does produce more power. successfully installed and used in experimental aircraft. Bud built his 383 cubic inch Chevrolet to produce the www.ContactMagazine.com
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sturdy prop shaft through spur gears, and ultimately to the crankshaft by means of an input shaft, exactly the way an engine works with an automotive transmission.
Photo: Pat Panzera
Bud’s plane on the flight line at AirVenture ‘06 most torque in the 2500-4000 RPM range, and his choice for gear reduction ratio is 1.562:1. This allows the propeller to turn at optimal RPM for efficient propulsion at a given speed, and runs the engine at an RPM that will allow it to also function efficiently, extending engine life. There are many who are currently using automotive engines in their experimentals, directly driving the propeller off the crankshaft, and some of those folks swear by their design. Bud had reservations about this type of engine setup and mentions that almost anything will work for a while. It is true that direct drive works on certified engines. However, many may not realize that unlike aircraft engines, automobile engines have crankshafts with narrow main bearings and were not designed to bear the side and thrust loads that a propeller would apply. Certified engines have crankshafts that are shorter, stronger, and their main bearings are many times wider, simply put, designed to bear the load of the prop. On auto engines, the snout end of the crankshaft was designed and engineered to drive accessories only. Long-term success for auto engines in airplanes is determined ultimately by the ability to utilize the engine in exactly the way it was designed to be used in an automobile. Bud’s redrive achieves this goal by driving the propeller off a short Prop Governor drive
Flywheel Idler shaft
Input shaft
Pressure plate CAD rendering of the PSRU assembly as seen from the engine side. www.ContactMagazine.com
Bud believes that one should never exceed what the engine is happy with, in other words, what it was built and designed to do. He never pushes his engine past a very conservative combination of engine RPM and manifold pressure (3,900 @ 30” T/O and 3,300 @ 25” cruise) and sees great performance combined with low fuel burn.
BUILDING THE ENGINE Bud chose Chevrolet for his engine platform because their engines are already performance proven and easily produce good torque and horsepower at moderate RPM. Because Chevrolet is an everyday household name, some people don’t seriously consider it as an engine for an airplane, even though Chevrolet has won more awards and auto racing titles than any other make. No big secret; plenty of information is available to build a Chevrolet powerplant for an airplane. The old, timehonored way to bring one of these engines together is by custom-building your own engine using separate Chevrolet components. However, Bud has some simple guidelines for the avid homebuilder: stay away from racing builds. A visit to a racing shop can end up being a disaster if lacking some basic engine build jargon. These fellows are professionals and experts at producing maximum power at 8,000 RPM or more. Rarely will you find shops that build engines suitable for powering aircraft. Having said that, you might find a shop that understands your specific power requirements. Bud recommends the build of a “tractor” engine, another racing term for a conservative build. Bud’s recipe for a successful outcome are high compression heads with a ratio not exceeding 10:1 and choosing the smallest volume (combustion chamber) heads you can buy, having small intake ports, small valves and small combustion chambers. Your choice of camshaft should be very conservative with low lift and duration, and maximum torque achieved in the 2500 - 4000 RPM range. This camshaft keeps timing duration and lift short, producing high velocity flow and higher torque at lower RPM. Coincidentally, this combination is the least expensive to build. The popularity of Chevy small-block engines is a result of its support by aftermarket parts vendors and their customer base. As a result, Chevy parts are generally less expensive and easier to come by than those offered to Ford enthusiasts. Because Bud did not choose Ford as his original engine platform is not an indication that he does not believe in Ford. Many are flying Ford engines currently with much success and Bud has already adapted his Geared Drive for 302 Ford V8s. In fact, Bud recommends Ford’s V6 for those applications requiring 150-180 HP since it is both lightweight and compact. Throughout the automotive world, there are a wide variety of different makes of engines that can be adapted for successful use in an experimental aircraft.
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Water reservoir
Throttle body
Bendix fuel injection spider 90° distributor adapter
MSD coils
MSD distributor MSD coil joiner
Mechanical fuel pump PSRU oil filter
19” x 22” double-row aluminum radiator Building an engine yourself or finding a shop that will build what you need can sometimes pose more challenges than it’s worth and, thankfully, there is an alternative to “do it yourself” (DIY), which could be more attractive to the typical experimenter. A tip for the DIY’er, salvage yards are a good source for modern engines. Look for fresh wrecks, low mileage and all uncut engine wiring. But if you are really going for the biggest bang for your buck and time investment, you don’t have to scour the salvage yards or try to build your own engine. You could go the easy and reasonably inexpensive route with a new Chevrolet crate engine. One choice could be a 400 horsepower V8 Chevrolet for less than $5,000. An outstanding buy, and all brand-new right out of the box, professionally built and usually with a warranty. An LS6 Corvette crate engine, which also produces around 400 HP, can be purchased for around $5,500. Additional money will, however, be needed to buy the electronics and engine wiring harness that do not come with most crate engines but are available on the aftermarket.
ENGINE SETUP Bud’s Chevy engine has been flying in his Wheeler for a little over three years to date. He admits his setup is old technology, as it is an early style 350 engine with a stroker kit, producing 383 cu in. Bud knows these earlier model engines inside out, and prefers them because he www.ContactMagazine.com
says they are just a little bit lighter weight than later model engines. His 383, complete with all accessories, (less propeller and radiator), weighs in at 454 lbs. and is actually lighter than a twin-turbo’d IO-540 that produces 100 HP less than the 383. Two MSD ignition modules reside inside the cabin with two MSD ignition coils (mounted on the engine side of the firewall) and an MSD distributor. The latter was modified to reduce cowling clearance by a custom 90-degree rework of the distributor shaft and its seals. This modification hides the distributor body between the engine valve covers. Later model EFI engines do not have distributors, which allow a neater installation and engine compartment. Only one set of plugs in this engine. Attempts by others to add a second set of plugs to a set of Chevrolet heads have resulted in cracked combustion chambers and other problems. Sparkplug redundancy is an area that Bud is not concerned about, as his experience is most modern automotive engines in good repair just don’t have problems with fouling spark plugs. Even so, Bud says, foul one or two plugs with a V8 engine and you can still fly to safety with six or seven cylinders still firing. The engine might run rough, but it will run. To date, with 660 hours on the engine, Bud has had no spark plug fouling issues or any other issue related to using a single plug wire per cylinder and a single distributor.
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Photo: Pat Panzera
Left: Radiator intake.
Middle: Front view of cowl showing radiator inlet and fresh-air scoop.
Right: Fresh-air intake.
COOLING SYSTEM Bud runs a 19 x 22 inch, two-row radiator that he purchased from a sprint car racing parts supplier and has no problem with cooling. He used an old racing trick that he says increases the radiator’s cooling capacity by splitting the water tank on the radiator, blocking it off to allow the water to make one more pass through the cooling tubes; he says he gets one third more cooling capacity than he would have otherwise. Originally, Bud tried taking in air through the stock Wheeler intake openings. These were rounded and quite close to the heads, which apparently kept any air from entering the cowling. After much scratching of head and wiping of brow, Bud blocked off these round openings and installed a small side scoop on the cowling to route air over the radiator coils. This did the job. The actual opening of this side scoop is smaller than what is used on some of the LSA types using a lot less power. A coolant header tank, mounted as high in the engine compartment as possible, is used to purge air in the cooling system. Both temperature and pressure gauges monitor this. A drop in water pressure will show on the gauge and give a pilot enough time to descend and land safely before any damage is caused by any potential leaks. Bud does not use a thermostat in order to avoid boil over problems from a sticky thermostat, which would be hard to deal with while flying. He simply removes the thermostat center and uses the outer ring for gap sealing and to slow the water flow a bit through the system. 40º OAT renders 175º water temp
built the engine because this technology was familiar to him and he knew it would be trouble free. Stock EFI would be a good choice and has the added benefit of automatically adjusting for altitude. Any system you chose can work just fine, just be sure to know your system, its drawbacks and how to use it safely and properly.
Another little trick that Bud uses is to route two water lines off the thermostat housing, drill and tap two holes in the opposite end of the intake manifold water jacket and install fittings, thereby attaching two hoses to the fittings. This helps with engine cooling as it allows cool water to circulate more uniformly in the engine.
Bud set out to design and build a redrive that he could be confident in flying behind, but this proved to be a huge challenge. Bud’s original geared redrive design was not very successful. A marvel of design in billet aluminum, it looked great from a machinist’s point-of-view. However the case was made up of five pieces and consequently it leaked oil, even after many attempts to keep it from leaking. Despite these leaks, the redrive was tested on the engine to see how the design would perform. It proved successful and functioned exactly as intended but the gearbox and engine combination produced tremendous issues with starters. Starter life expectancy was bleak as it was obvious that the starter would not be able to hold up against the inertial resistance of the constant-speed propeller and the geared redrive.
CARBS vs. EFI Bud has no strong opinions either way regarding fueling methods. Carburetors are simple devices and require little attention if properly maintained, however carburetor icing can be a factor to consider. Standard aircraft fuel injection systems are indeed old technology, but are dependable and eliminate electronics. Bud chose to use a Bendix aircraft system in his Wheeler when he originally www.ContactMagazine.com
TURBO vs. BLOWER Bud has some strong reservations about turbochargers installed in experimental aircraft. His personal and rather strong opinion is that it is not safe to have a “white hot flaming ball of fire” under the cowling. His strong opinion arose from hands-on experience as a certified mechanic. Turbos are expensive to install and maintain and, by their very nature, can shorten engine life. Bud is, however, an advocate for blowers (belt-driven superchargers) and says that if they are properly setup they should not have a negative effect on engine life. Superchargers were standard equipment during his racing days; he has plenty of good experiences from which he draws confidence, and as such he’s an advocate of their use. According to Bud, you can supercharge a Chevrolet race engine for $3,000 compared to the cost of turbocharging that can reach as high as $20K (for a twin turbo, intercooled system) mainly due to the necessity of a rather expensive and exotic exhaust system required for use with a turbocharger.
REDRIVE SOLUTION
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1. After torquing the flywheel in place the pilot shaft bushing is tapped into place.
2. The clutch disk is then set into place and springs (not shown) are installed into perimeter holes .
3. The pressure plate is then installed and secured by L-shaped brackets that will later act as a fulcrum.
4. Counterweights are attached to the L-brackets, completing the centrifugal clutch installation .
This problem was unacceptable and required a cure. Eventually, a solution based on heavy-duty engine clutch experience in Bud’s top-fuel race cars came to mind. These cars utilized a flywheel and several heavy-duty clutch discs, the latter being effective but not adaptable to the aircraft redrive solution. What would solve the dependably problems (in a rather crafty manner) was an automatic clutch that would replace the slipping, sliding, friction action of the racing clutch. Bud came up with an elegant design that connects the engine and flywheel to the redrive, gently and quietly engaging the propeller at low RPM once the engine is already running. The automatic clutch is tuned to remain disengaged at dead idle and become engaged with an increase in power. Engagement under all flight conditions is positive. Bud comments that people were astounded by the operation of the redrive. One of the most common questions asked was whether the clutch would disengage during flight,
and the answer is that it will not. Upon startup, the propeller engages once the engine RPM reaches around 1000, in a fluid and smooth action that is virtually imperceptible. The counterweights engage due to centrifugal force, and remain engaged while in flight, after landing, and all the way to the hanger; they will not disengage until the engine stops spinning. The automatic clutch simply will not disengage until the aircraft is on the ground and the engine is not running.
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Consider this: you are flying along at altitude, you run one tank dry and the engine quits firing. Of course, no one has ever done that but in this case, it is a non-event. Just switch to another tank and your engine restarts instantly because the propeller and engine are still turning, just as they do with any direct-drive, certified air-cooled engine. The cylinders are not loaded up or flooded, and the engine will start again.
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The redrive, less flywheel, weighs in at 63 pounds and requires the use of the flywheel to dampen engine impulses. Bud does not offer any “extras” to purchase with his redrive, as his design is simple, effective and complete. It also doesn’t require any engine modifications for use. The unit is merely a bolt-on to the engine and is easy to install. Bud publishes his installation manual on his website for all to see.
ion is that he personally would never purchase any aircraft components from any designer or builder unless they stood behind them enough to put their reputation (life?) on the line by flying their own products on their own airplanes. Don’t be fooled though; he doesn’t just go to the events to show-off his airplane and his redrive. He simply loves to fly this airplane and loves to demonstrate its performance to others, sales notwithstanding.
HARMONIC ISSUES RESOLVED
TBO of this redrive is expected to be extensive. Since the automatic centrifugal clutch operates in an off/on mode, Bud believes this component should last the lifetime equivalent to that of a new engine. This redrive multiplies torque to the propeller and does not impart any side loads, thrust loads, or end loads from the prop back to the engine crankshaft. After exhaustive research and days spent in the Rice University patent library, no similar device was found to have been issued a patent, so it would appear likely that a patent would be issued for the redrive and its unique features.
One of the big problems in any auto engine conversion is the matter of harmonic vibration which is a natural result of reciprocating engines. Simply put, the crankshaft is subject to firing pulses. These vibrations are moderated by a harmonic damper, custom-built to match specific inertial forces installed at the opposite end of either a manual clutch plate, or by the fluid coupling of the automatic transmission. Removing the transmission prior to installing the engine into an aircraft leaves one with the resulting issue of how to dampen these harmonic vibrations; half the tuned system is gone. To solve these issues in an experimental aircraft, solutions such as flex plates, elastomer donuts, driveline couplings, sprag clutches and other devices have been used; some of these dampening techniques were tried out in Bud’s earlier redrives but most offered unsatisfactory results.
REDRIVE COMPONENTS
A view from the underside of the redrive exposes the assembled centrifugal clutch mechanism, consisting of a counterweight attached to an L-bracket fulcrum. Rotation over 750 RPM causes the six counterweights to apply a uniform load to the pressure plate sandwiching a traditional-style clutch disk between the pressure plate and the flywheel. His redesigned and refined prototype has been proven in 660 flight hours to date and over 1,000 takeoffs and landings in his Wheeler Express. Bud flies to the air shows to demonstrate the performance and operation of his engine and redrive to other homebuilders. He thinks it makes sense to show others that he believes in his redrive by actually flying one in his own airplane. His opinwww.ContactMagazine.com
The three-gear layout places the prop 7-11/16 inches above the crankshaft centerline which increases prop clearance and fits most airplane cowlings originally produced for Lycoming or Continental air cooled installations. The standard prop rotation is maintained. The aluminum redrive case is assembled in two pieces. The parting line has an embedded O-ring, which prevents any oil leakage. All bolt attachments are reinforced with Helicoils, eliminating the chance for pulled threads. Eighteen bolts secure the front redrive cover, more than sufficient to resist prop thrust loads. The redrive utilizes three premium (and expensive) spur cut gears: drive, idler and final drive, all built to Bud’s specifications. Gear profiles have a smooth finish, kind of a frosted look prior to being used in the redrive. This combination has several advantages: spur gear profiles are stronger than helical gear profiles; there are no added issues with bearing end thrust loads; each gear has its standard tooth profile modified by a machined crown shape that optimizes tooth dynamic loads; and spur gear noise is not an issue with end users in the airplane envi-
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ronment. Proper backlash is critical and is set when the redrive is assembled by use of eccentrics on the idler gear shaft. In the event that a customer changes his mind about his gear ratio, it may be changed by shipping the redrive back to Bud for the cost of actual labor, materials and shipping. Photo: Nicholas Wood
Input shaft
Output (prop) shaft
less the non-synthetic, 75W 90 or 80W 90 gear oil is used. This is the same type of lube used in automotive differentials across the world and works perfectly in this redrive. This gear lube has been proven to produce minimal noise and heat. For example, with 75W 90 in the redrive, Bud flew his Wheeler in the Homebuilt Parade at Oshkosh AirVenture 2006, in 100+ degree F weather. The temperature gauge for the redrive oil temperature climbed to 150°, then at cruise around the patch, leveled out to 140°
Prop flange
Idler gear
Idler shaft
The main shafts (both input and prop) are made from premium stainless steel (17-4 PH) and heat-treated at 900º F, producing a tinsel strength of 195,000 PSI. This all but ensures an infinite fatigue life with no potential for cracking. The heat-treating process turns the stainless Photo: Nicholas Wood steel to a warm bronze color and causes it to resist rust and corrosion. The redrive has a separate lubrication system with its own independent oil supply and oil pump, which forces oil through a filter before circulating the lube at 60 PSI through all of the bearing surfaces, shafts and gears with every turn of the prop. Lubrication is achieved with success as long as transmission grade 75W 90 oil is used in the redrive unit. Bud’s opinion is that the kiss of death for an airplane engine and redrive is for the two to share engine oil. He insists that engines do not like gear lube, and gears do not like engine oil. Other than the typical visual inspection of lines and fittings, etc. maintenance of the redrive consists of changing the oil filter and checking the lube level every 100 hours. Standard 30W HD auto engine oil is Bud’s choice for engine lube. Bud tried five different types of synthetic transmission oils in the testing phase of his redrive. Each synthetic lubricant tested caused overheating and all were found to be inferior for use in this application. In fact, Bud will not honor the warranty that he offers on his redrive unwww.ContactMagazine.com
Propeller governor
The PSRU comes ready to install the prop governor of choice. This Woodward unit is installed inverted. The redrive has a geared boss on the side of the case which allows a standard aircraft governor to be mounted in the normal location off the prop shaft. The governor mounts upside down, which does not affect function at all. Many certified aircraft mount their prop governors in this attitude so it does not pose any problems. Since prop governors are standardized and share the same mounting pad, the redrive will accommodate all brands of governors. No blast tubes are required, no oil coolers, or anything beyond reasonable air circulation under the cowling has proven to be necessary to keep the redrive running cool. The operation of Bud’s PSRU is smooth, quiet, and doesn't produce heat, indicating an efficient design.
PROPELLERS The propeller of choice on Bud’s Wheeler is a three blade 80” prop cut to 78” for just a bit more clearance. “I personally like a three blade prop with a high horsepower engine because it gives you a little bit more climb. If the engine horsepower is not real high, I go for a two blade.”
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for Bud’s Express is As far as propeller typically at 15 GPH or manufacturers are conless (cruise), and cerned, Bud says you clocks about 180 MPH. can put just about any propeller you want on ENGINE MOUNTS his transmission. “I prefer to install a Hartzell Bud has become on my plane, but there aware that many exare many companies perimenters have a that make good propelstrong desire to use an lers. However, I think automobile or other you get more bang for alternative engine in your buck with a contheir experimental airstant speed prop than craft, but find that conyou do a fixed pitch, sidering such an enalthough my redrive will deavor (especially if it’s work with either equally not supported by the kit well. I just believe in manufacturer or deconstant speed propel- Side view of the subject engine, showing the location of the signer), can create a lers because you can prop governor and a good overall view of the engine mount. boat-load of challengget better efficiency out of it; you can climb a little faster es. Many do not have the knowledge or ability to personand cruise with better economy.” ally build an engine mount for their engine/airframe combination, nor do they have The PSRU will also work access to anyone else who well with beta-mode capadoes. Necessity being the ble and self-feathering mother of invention, Bud props. Feathering is offers custom engine achieved because of the mounts for individual expericonstant oil supply to the menters and is currently redrive, which means that designing engine mounts an oil accumulator is not for many of the popular kits. required. In the event of an This ability comes from his engine failure, the prop will racing days and experience still turn and positive oil in building racecar chassis pressure still exists. In theofor high performance racery, one could install a prop cars, so building engine capable of beta-mode and mounts is second nature. put it in reverse to back up if so desired. Bud is a master machinist and certified aircraft welder Bud’s “transmission”, as he The PSRU lubrication system including oil filter and with many years of design likes to call it, will work with high-volume oil pump. and troubleshooting experiHartzell, McCauley, MT Propellers, or virtually any other ence to his credit, both in the aviation and in the automopropeller that is chosen for use. Since these redrives are tive world. At his home FBO, Bud is known as the “go-to” built and assembled with the individual aircraft and appliperson when it comes to fabricating anything that has to cation in mind, propeller shaft flanges can be drilled and/ do with an airplane. Locals know him as the person who or lugged to accommodate any bolt pattern in addition to can repair anything from certified engines to automotive SAE-1 and 2. engines, to airframe and lots in between. In fact, Bud totally restored a Consolidated-Vultee BT-13A Valiant, PERFORMANCE sponsored and flew it in air shows for three years. This airplane still exists within the organization that we know Bud is completely satisfied with the performance of his of today as the “Commemorative Air Force”* and has 383 Chevrolet. Initial climb out is 4000 FPM plus. Since been customized to look like a Japanese Val bomber. At Bud’s home airport is close to sea level, manifold presthe time, this airplane was considered the fastest airsure on run up indicates 30 inches. At 11,000 feet altiplane in its class within the organization. This Val still tude, the engine still is pulling 19 inches manifold prescarries the words “Lovingly built by Bud Warren, master sure. In keeping with Bud’s philosophy of not working the craftsman”. engine hard, his engine and redrive combination produces 3,900 RPM on take off, with cruise around 3,200 en*The Commemorative Air Force (CAF), formerly known as the gine RPM. Consequently, the prop turns an ideal 2,500 Confederate Air Force, is a Texas-based non-profit organizaRPM on take off. At cruise speed with engine RPM of tion dedicated to preserving and showing historical aircraft at 3,200 RPM, the prop turns around 2,100 RPM. Fuel burn airshows primarily throughout the U.S. and Canada. www.ContactMagazine.com
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With form following function, the cockpit of N901RC is fully appointed as a traditional IFR machine with everything right where it should be, in addition to being comfortable and as attractive as the exterior would suggest.
TEST-BED AIRCRAFT The proof-of-concept airplane is a four place, fixed gear, composite airplane called a Wheeler Express. This airplane weighs in at 2100 lbs (empty) and has a gross weight of 3200 lbs. It was originally purchased as a Wheeler C/T kit; however, prior to the airplane being completed there was a deadly crash of a Wheeler C/T which stopped other kit owners in their tracks. Wheeler owners apparently got together and consulted an engineering firm which determined that the tail surfaces for the C/T were simply not large enough for proper control and safe flight. Prior to completion of Bud’s Wheeler, the
more substantial tail-section for the newer model Express was purchased and took the place of the smaller C/T tail section. The resulting conversion makes the plane handle and fly well, and does not have any control weight issues with full capacity. “This is a working airplane,” Bud says. He spends so much time with his customers and their projects that he doesn’t have a lot of time left to work on his own plane. Performance and safety being the main concerns, his efforts go into the continued development of the design and function of the automotive conversion, which he loves to share with others. Bud is a humble man and is happy to share his experience with others. He says, “I’m glad to tell anybody all the information they need to know. I keep a telephone in my ear all the time and if people call me to pick my brain that is fine; I am happy to share information”. “I help people who are not even my customers. I just believe in trying to help people get these airplanes flying with auto conversions because I know that they are going to be a lot happier. I just like to get there fast, not spend a lot of money, and get back safely. I think a lot of other people want to do that too.”
Bud’s handiwork: A restored Vultee BT-13A, modified to resemble a WWII era Japanese Val bomber, now a part of the Commemorative Air Force. www.ContactMagazine.com
Phyllis Ridings-Murawski Phyllis@Phyllis4RealEstate.com
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Photos and story by Mark R. Steitle Austin, TX msteitle@gmail.com A carryover from our issue #88 (the all-rotary issue) this article was submitted with all the others. Since the project was incomplete and since I had more than enough articles to fill that Issue, I opted to print this article at a later date; that date has come. ~Pat What was it about the rotary engine that I found so intriguing? Its difficult to say for certain, but my fascination goes way back to the early days of the rotary powered NSU Spider*. I have never owned a rotary-powered automobile, but when I decided to build an airplane, the rotary was my engine of choice, no question about it. When I learned of the 20B three-rotor (as opposed to the more commonly used 13B two-rotor), the decision was made, that was the engine for me.
THE AIRFRAME SELECTION I purchased a low-mileage 20B rotary engine from Shane Racing of California. www.shaneracing.com It was shipped by truck from California. I picked it up at the shipper’s dock and felt like a new daddy. OK, so now what airframe should I use? Yes, I picked the engine before selecting the airframe. To me, they needed to match. The airframe needed to be up to “rotary standards” and the Lancair ES was perfect. As it turns out, it was a good choice. The weight & balance came out right on the money and there is plenty of room for all the necessities with room to spare. The four-seat airframe is very roomy and will make a great cross-country traveler.
550N engine, would make the first step in the conversion much easier. Since the nose gear is integrated into the motor mount, I chose to use the stock bed-mount and fabricate adapters from 4130 tubing to connect the rotary engine to the mount. Knowing how to TIG weld really came in handy on this step of the project. While it was no easy task to build these adapters, it would have been much more difficult to design and build a new mount from scratch. Being able to use the existing mount was a real time-saver.
INTAKE MANIFOLD With the engine solidly affixed to the motor mount, I tackled the intake manifold. The stock cast aluminum manifold was way too tall and heavy, so I fabricated my own tubular intake system. Attempting to take advantage of the tuning effect, I built a wrap-over manifold and plenum using pre-bent aluminum tubing from Burns Stainless, another California company, that sells quality mandrelbent tubes of all shapes, sizes and materials.
Close-up of adapter.
Backing up a moment, mounting the rotary engine wouldn’t be easy. But the Lancair’s dynafocal motor mount, being designed for the Continental IO-
www.burnsstainless.com This undertaking was a real challenge, as welding the different Stock Lancair ES engine mount adapted for thicknesses of aluminum is not for the faint of heart. The intake the three-rotor 20B Mazda rotary engine. plenum was fabricated *Launched in 1964, the NSU Wankel Spider, an open top verfrom .125 aluminum sheet. Ram air enters a custom fision of the Sport Prinz bodyshell designed by Bertone, was the berglass plenum in the right cowl inlet and then through first production car in the world to use a Wankel rotary engine. a “for off-road use only” 95mm Holley throttle body. The The Spider soon demonstrated the revolutionary engine's potenengine is fuel injected with three 550cc primary injectors tial in competition: In 1966, Karland three 550cc secondary injectors, controlled by a ReHeinz Panowitz/Rainer Strunz al World Solutions (RWS) EC-2 ignition/EFI controller. won the German GT Rally ChamDual Wallbro fuel pumps provide the necessary fuel to pionship; the following year, Siegkeep the rotary humming. The EC-2 also controls the fried Spiess won all classes of the firing of the six LS-1 Corvette coils, one per plug. German Hill Climb Championship. www.ContactMagazine.com
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A good view of the intake runners and Tracy Crook’s RD-2C propeller speed reduction unit. Fiberglass fresh air intake, 95mm Holley throttle body and custom .125” sheet aluminum plenum. Since my Lancair was to be all-electric, I opted for dual 55A ND alternators (externally regulated), and dual Odyssey PC680 batteries, with the crossfeed option as described in Z-14 of the Aero-Electric Connection. My welding experience paid off once more with the fabrication of a custom eight-quart oil pan. A redesign was necessary as the sump in the stock pan was at the wrong end. The pan includes an integrated windage tray.
EXHAUST SYSTEM The exhaust manifold was fabricated from 2” diameter, .140” 304 stainless bends, turning into a 3” main runner.
The gear-reduction unit is also by RWS. It is their RD-2C model, a 2.85:1.0 gear ratio, utilizing a six-pinion planetary gear set. The prop is a 3-blade electric M/T constant speed unit. The RD-2C prop flange needed to be modified to accept the M/T prop bushings. This delicate task was farmed out to a retired machinist friend, Bob Darrah. The 20B water pump housing would have stuck up above the cowl, so it had to be cut down. I replaced the gooseneck with a flat plate and brought the outlet out the front of the housing, solving the problem. All connections are of the “wiggins” design and all radiator lines are fabricated from aluminum tubing. An undersized crank pulley was used to slow the water pump down a little. Water cooling is through a C&R aluminum 2-row radiator located under the engine and in front of the nose strut. Cooling air is with a chin scoop. Oil is cooled by a 12 x 12 Modine cooler located behind the left air intake. Fast forward seven years to March 2, 2007, which was the day my rotary powered Lancair ES first moved under its own power. What a thrill to finally taxi my pride and joy! The taxi test lasted for about 30 minutes. All temps and engine gauges were in the green and the rotary was begging me to unleash the horses. It was all I could do to keep from pouring on the coal and taking off into the beautiful blue Texas sky, but my better judgment took over and I pulled back on the throttle. I must wait a little longer for the DAR to bless the paperwork and sign the airworthiness certificate, but I was grinning from ear-toear for the rest of the day. The magical day is just around the corner. Stay tuned for my first flight report.
The 2” tubes were press-fitted into the flange and then welded on the engine side of the flange, to prevent cracking. The rotary has a reputation of destroying mufflers and exhaust systems. Mine is a little heavier than most, but I am confident it will last. The exhaust note is somewhat quieted by an exhaust baffle. It has been measured at 103db at 4,000 rpm, measured at the wingtips. This was with the 3-blade M/T prop installed. While not exactly quiet, it isn’t any louder than most other a/c on the field, but it does sound very different. One observer described the sound as a “Rotax on steroids”. I kind of like that description. www.ContactMagazine.com
While editing this article, I received the following from Mark: Some of the recent changes are 1) Sent the EC-2 back to RWS for the snubber upgrade (see CONTACT! issue 88), and 2) While it was at RWS, I had Tracy convert it over to work with the newer style crank angle sensor (CAS), like the one used on the Renesis. (That's another story in itself.) 3) Added a K&N crankcase breather in the hole left by the original CAS, 4) Replaced the 95mm throttle body with a 75mm TB, and 5) Tune, tune, tune. She's running pretty good now. I have the cowl off now, in preparation for the DAR visit on Monday. Maybe I'll have a first flight photo for you soon.
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Larry Morgan, President and C.E.O. Dave Hansen, Operations Manager Maggie Roth, PR Manager Pitch Control Systems, L.L.C. 12505 S.W. North Dakota #105 Tigard, Oregon 97223 Ph: (503) 804-5508 e-mail: lmorgan724@yahoo.com web site: www.variprop.com By John P. Moyle and Patrick Panzera Photos by Patrick Panzera With the vast number of current airframe designs available, an equally fast growing list of powerplant choices, and nearly limitless flight missions, selecting a fixedpitch propeller for a specified job has proven to be a matter of selecting a model which hopefully gives decent performance in the most critical flight regime without sacrificing too much in the rest of the spectrum. A well designed ground-adjustable prop offers improved performance, even within the Light Sport Aircraft category. Even though the rules restrict many things they still permit ground adjustable propellers. The experimental aircraft builder who has Paul Lipps (left) and Larry Morgan (right) share the spotlight in our chosen an alternative engine, or an auto- magazine sales booth at the recent (2007) Golden West Fly-in. mobile engine conversion requiring the use of a propeller speed reduction unit (PSRU) has been display mounted to such an aircraft at the Sun N' Fun Air even more severely restricted when it comes time to seMuseum. The design was sold to a British concern but lect a propeller. In almost every case, the use of a certiwas never moved into production. Eventually, the design fied-type, constant-speed prop is out of the question. rights came back across the Atlantic and are now owned This leaves very little in the way of options; there are by Larry Morgan and Dave Hansen of Pitch Control Syssome props out there which offer ground adjustability, tems, L.L.C. The facility is located at the Aurora, Oregon, and some with electrically driven blade twist. airport which is also the home-base of Van’s Aircraft.
ENTER THE SOLUTION The unit we will be discussing today combines the positive features of a hydraulic blade pitch control with a special panel-mounted constant-speed control mechanism that mimics a traditional vernier-type installation. Best of all, it requires neither a drilled crankshaft nor an expensive governor unit. It can be used on every possible application we can think of that’s capable of handling the installed weight– certified or not. Of course some smaller engines such as the VW or Corvair won’t be able to take advantage, but just about every other engine, from Jabiru to Rotax, Subaru and Mazda, through the biggest Detroit iron available should be able to bolt this beauty on and see a dramatic difference. The Vari-Prop is the reborn version of a very clever design which originated in 1978. The brainchild of Morris Elliot and designed specifically for the BD-5 experimental aircraft, the original prototype Vari-Prop is on prominent www.ContactMagazine.com
The editors of CONTACT! Magazine encountered these fine gentlemen at the Sun N’ Fun event in 2006 and immediately recognized that they possessed the critical hub component and manufacturing capability that we had been unsuccessfully trying to find for Paul Lipps’ unique propeller design that we debuted in issue #77 back in 2004 and showcased in issue #79. (Both of these articles are reprinted and available in our current “special” issue, #88.5. See Pat’s editorial for more information.) After a good look at the impressive engineering and obvious quality of the Vari-Prop product it became apparent that we needed to get these guys together. That has now come to pass and subsequently the very efficient Ellipse blades are finally commercially available, mounted to a Vari-Prop hub. The hub supports either the fast and simple ground adjustment feature, or the constant speed hydraulic adjustment and until now, the only way one could obtain an Elippse prop was to have a one -of-a-kind custom unit hand-carved.
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BLADES The standard Vari-Prop unit can still be purchased with conventional blades, the same type that have been rigorously tested on Jess Myers’ RV-6 test bed powered by his Chevy 4.3 liter V6 conversion featuring the PSRU that his company, Belted Air Power, produces. www.beltedair.com (Parallel testing has also been conducted in Vari-Prop President Larry Morgan's O-320 powered RV-6). Long-time subscribers will remember Jess from issue #19 when we showcased his Buick 215 powered Globe Swift. Jess also contributed follow-up articles in issues 35, 43 and 63. Those fortunate enough to attend our engine forums at COPPERSTATE, Laughlin and Jean NV should recognize the name as Jess tries his best to support our educational efforts and is always ready to give a forum any time we ask. Jess raves about the Vari-Prop and has some really impressive performance numbers to share. We’ll have a detailed story along with additional test results when he finishes wringing out the new Elippse bladed version soon. For those who are not completely familiar with the amazing Elippse prop design, we again recommend that you purchase our special edition # 88.5 which contains a reprise of previously published articles on this topic from several earlier editions.
The Elippse/Vari-Prop as seen in our booth at the Marysville Fly-in. Although not as radical as the propellers designed for and currently flying on Paul’s Lancair and the Reno Biplanes, it’s easily recognizable as a Paul Lipps design. The biggest reason that it looks tame by comparison is that it’s designed to cover the spectrum of Van’s RV’s designed for 150-200 HP, irrespective of airframe. Unlike any previously manufactured Elippse propeller, all of which were designed for a very specific plane with a very specific mission, this prop is designed more to be the RV builder’s best friend and not to be fastened to the nose of a fire-breathing Reno racer.
The propeller blades are manufactured by Jeff Bertuleit’s “Props, Inc”. www.propsinc.net, a highly regarded propeller carving shop with more speed allowance was calculated in accordance with the than three decades of experience manufacturing propulFAA regs for the model tested, and Coon-Hall Laboratosion systems for experimental aircraft, including groundries of Milwaukie, Oregon, was contracted to test the adjustable wood props. The blades are made from 1/16 inch laminates of Eastern Sugar Maple, a material Precision-ground known for its high modulus bearing “race” (two of elasticity. The process per bearing) includes the required number of laminates for the specified blade thickness, resorcinol glue cured under high pressure and high heat. This manufacturing Third style has proven to deliver bearing high-strength blades of surface Free-floating great reliability. They are threaded collar available either with or without composite sheathing, and painted to your Roller thrust color choice. bearings Blade position control rod The machined aluminum root ferrule features an Blade retention into the hub is very simple; a threaded collar mates to the correaircraft grade epoxy reten- sponding threads in the hub and is tightened (by way of a pinned spanner) to pretion system that includes load the thrust bearings, much in the same way that an automobile hub is affixed lag bolts and two 90° cross to its axle. No specific torque number is specified; it’s more of a “feel”. Bearings pins. A 9,000 lb. over are lubed with the same grease as that used for Boeing 747 wheel axles. www.ContactMagazine.com
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Third bearing
Thrust bearing surface
Retention bolt
Prop hub attach flange Drive pin
“Spool” Spring
Hydraulic line air-bleed Schrader valve
Piston assembly
Hydraulic supply line fitting
blade-to-hub integrity. An incredible 27,950 lb. result was achieved without failure. The blade position control rod, seen on the perimeter of the blade root, is the component that the spool operates against in opposition to the spring The roller thrust bearing is sandloaded default to wiched between two precisionminimum pitch. ground steel races. Only one is The aerodynamic shown in the photo above. blade loads also tend to rotate the blades toward the default position. The blade rotates inside the hub with a very precise and almost frictionless fit. This is accomplished by the use of three sets of bearings, two of which are roller thrust bearings that permit the rotation of the blades while under load. Although the blades rotate slow enough to be barely perceptible, these bearings are rated at 9,000 RPM. The third bearing basically locks the blade in two axes and along with the threaded collar, maintains uniform loading of the thrust bearings
Prop flange the only moving part in the entire system and it’s under virtually no load other than the spring it works in unison with. The real loads of the system are transmitted through a steel center shaft with flanges at either end. One end is attached to the engine like any other propeller while the other end supports the aluminum hub that, in turn, carries the full load of the propeller. The previously-mentioned spool and piston assembly are simply along for the ride, isolated from any of the horsepower or aerodynamic loads. But they do have to be installed
HUB DETAILS The “spool” previously mentioned is the motive force of the blade movement toward increased pitch, whether mechanically operated by the single adjustment bolt in the ground operated unit (an absolutely simple process which does not need anything but one tool to accomplish), or hydraulically operated from the cockpit in the case of the constant speed unit. Besides the piston, it’s www.ContactMagazine.com
The removal of the central retention bolt allows the steel shaft to be split for the removal of the spool, spring and the piston assembly.
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Propeller hub adjust mechanism. CAD rendering by Patrick Panzera. Absolutely NO SCALE.
One of two travel limiters which in conjunction with the spring, stop the rotation of the blade at its finest pitch setting.
One of six drive pins
One of six bolt holes
Steel hub
Spring
Aluminum “Spool”
Control rod guide
Type II spline, all rounded edges
Roller thrust bearing Piston Aluminum piston assembly Oil bleed passage
Oil delivery passage “Slave cylinder”
SAE-1 SAE-2 bolt circle
Fafnir ball bearing Prop hub flange
www.ContactMagazine.com
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between the flanges, which would be impossible to do unless something was split in two. In this case, the elegant solution was to split the steel shaft and reassemble it by way of a splined fit. The two-part splined steel hub center section (pictured on the previous page) and the aluminum hub work is handled by business partner Helzer Machine, Inc of nearby Clackamas, Oregon. Helzer is a CNC shop which Vari-Prop has great confidence in, and from the pieces we’ve seen, justifiably so.
Medium duty two-blade version as seen at SnF 2006. As an example of weight, a typical three-blade constantspeed propeller for an RV-6 will weigh 33 lbs. at the hub.
HYDRAULICS The hydraulic control pump weighs 3.5 lbs. and can be mounted anywhere in the airframe for weight and balance purposes. The term “pump” is used loosely, but don’t be misled to believe that this is an ordinary pump in the traditional sense. In really it’s a custom-built (proprietary) electrically actuated master cylinder.
Although a bit worn and dirty from being lugged from show to show, the quality of the machine work is explicitly apparent. Pictured here are a medium duty hub (good up to 200 HP) and a heavy duty 400 HP version destined for the airboat industry. Not pictured is the smallest of the three, designed for engines in the 80-120 HP range, aimed at the Jabiru. The propeller hubs are machined from a single billet of Aircraft grade 2024 aluminum and all conventional prop bolt patterns are available. The hardware is all AN quality and safety-wired per the FAA Advisory Circular: AC4313B, the” Bible” for aircraft maintenance practices. Assembly of components is done at the Aurora shop.
Motor Master cylinder
Limit switch
Medium duty four-blade version as seen at SnF 2006. The Vari-Prop is available in two-, three- and four-blade versions to suit just about every need. The four blade models are expected to be most popular with the replica fighter groups. www.ContactMagazine.com
The display we had at in the booth at Marysville was 100% complete and functional. Any single component could have been unbolted from the stand and installed in an experimental aircraft. The pump was installed horizontally (as shown above), but it can also be mounted vertically with no modification. The above photo shows a small, gear reduced electric motor on the right, which through a set of gears on the other side of the mounting plate (not visible in this shot), operates a screw-driven piston inside the master cylinder shown on the left. A circuit board on the far left translates the pilot’s intentions into commands to the motor, moving the piston in either direction. A limit switch senses the travel position and will
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A single small-bore hydraulic line is routed from the pump to the back of the prop hub and simple wiring runs to the panel mounted prop pitch control. This system is equally at home on direct drive, cog belt or chain redrive type, or geared PSRU installations thanks to the ingeniously located piston inside the prop hub. The piston is affixed to the central shaft by way of a press-fit ball bearing. With a sturdy bracket (from just about anywhere on
Another view of the “pump” giving a better showing of the circuit board and a look at the gears. The circuit board has undergone rigorous laboratory testing for heat, shock and other endurance factors and has come out with good report. cut off the power to the motor when piston travel reaches its maximum position. This is set by running the engine to full static RPM, shutting it down, and adjusting the switch to coincide with the current piston position. With the prop control vernier knob in the cockpit, a single push forward on the knob will put the prop to its flattest pitch, as defined by the limit switch.
Piston assembly Break-away oil fitting
Bearing the engine or PSRU) securely affixed to the break-away hydraulic line fitting, the piston assembly position is fixed and doesn’t rotate with the shaft. The spool portion of the mechanism rides on the piston but rotates with the hub. The mating surfaces between the stationary piston and the rotating spool are also high RPM rated roller thrust bearings lubed with 747 axle grease. Should the ballbearing that supports the piston assembly seize or otherwise fail, the hydraulic line won’t become entangled with the prop as the inlet fitting is scored and designed to shear with little force, freeing the piston assembly to rotate with the propeller assembly. Some oil will probably get on the windscreen, but that would likely be the worst of it.
The panel-mounted vernier-style control knob is normally painted blue, but the display unit began to flake so Larry removed most of it before the Marysville event. A throttle quadrant version is currently in development. The circuit board, once hooked to the #1 spark plug, is also capable of reading the engine RPM and governing engine speed to maintain the pilot’s setting irrespective of throttle position or climb angle. With the tactile feedback from the propeller control knob (pictured above), the pilot of an experimental aircraft equipped with this prop will notice very little operational difference between what he’s currently flying and any certified, complex, piston powered aircraft that he’s flown in the past. www.ContactMagazine.com
At the 2007 Golden West EAA Fly In at Marysville, California, a fully operational Vari-Prop with Elippse blades was debuted in the CONTACT! Magazine booth and received a great deal of attention. With either the standard blades or the “radical” Elippse blade design, there is a lot of interest in this new product. Current delivery is slated at 45-60 days from time of order placement. The introductory price for a three-blade constant-speed prop (all mounting hardware included) is $7,995 through the end of AirVenture 2007. It weighs in at 33 pounds. The ground-adjustable version is only 1.5 lbs lighter at the hub, and without the pump, the total weight loss is right at five pounds. The OSH special for the groundadjustable three-blade Elippse prop is $4,995, and standard two-blade unit will be sold for $4,495. Vari-Prop is proud to proclaim that their props are 100% American in design, materials, manufacture, and assembly.
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By Steve Makish SRMAKISH@aol.com A couple of months ago while on a routine recreational flight in my Corvair powered KR-2S, I was inbound to Boca Raton Airport BCT (my home airport) arriving from the northwest. I called the tower from 10 miles out and was cleared to descend from 3,000 feet to 1,000 feet and make mid field left downwind for runway five. A few minutes later I heard a Gulfstream check in and request a landing coming in from the southeast from the ocean. He was cleared for left downwind runway 5 as the controller thought he was closer and faster than I was. He did not alert me to traffic until I spotted him out of my peripheral vision. I asked if he was landing at BCT and the controller went nuts.
The display shows traffic at 5 NM and 10,700 feet above my altitude (probably an airliner).
I was only a few seconds from a collision with a plane that was at my altitude, 500 feet off my nose and closing fast. I just pushed the stick over and went virtually straight down and pulled out at 500 feet AGL. I could see the co-pilot with his eyes as big as saucers; I missed him by about 250 feet. As George Carlin would say, that is not a near miss, that is a near hit! I did not get ticked-off until I landed. I jumped in my truck and headed to the tower with our impotent "Barney Fife" security guard chasing me with his yellow lights flashing. I got out and told him to bug off, as I had business in the tower. They knew I was coming; I had already alerted the controller and they unlocked the door prior to my arrival. We had a real heart to heart. The Gulfstream did not do as he was told, he slowed up too much and drifted way west of where he was supposed to be, putting us both at the same place at the same time. The controller admitted he took his eyes off the screen during a shift change and was almost in tears with the reality of what could have happened, as we know these guys on a first-name basis. What really irked me the most was the Gulfstream driver’s arrogant refusal to accept any blame whatsoever for the incident, even though he was clearly in the wrong. He even asked if my transponder was working, to which the tower replied "yes". “Well I guess my TCAS isn't working.” was his cavalier reply. After this incident I decided to protect myself by purchase a traffic monitoring system. So far it’s worked just as advertised and I’m glad to have it onboard. It has two verbal messages. “Traffic Alert” is spoken if the traffic is 3 nm or less from my position. “Traffic” is spoken if the traffic is 5 nm from my position. It is well worth the $600 investment and I highly recommend it. It does not give you a direction for area traffic, but tells me distance and approximate altitude in relationship to my altitude. It ignores your onboard transponder and is a passive device. It’s the Monroy ATD 300 and you can read more about it on their website, www.monroyaero.com www.ContactMagazine.com
1 NM and 200 feet, just took off past my hangar.
Normal state, no traffic shows a/c voltage.
3 NM and 4200 feet.
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SWITCH ON! Continued from page 3
note from him that his DAR inspection came back with a clean bill of health so he’s now legally free to perform his first flights. With the announcement of the Elippse Prop coming to market, it became important to us to reprint any article by Paul Lipps, since every issue he’s been in has completely sold out. So we compiled all his articles into one “special” issue that we’ve dubbed Issue #88.5. This issue is currently available to purchase as a back issue, just like any and all back issues are available for $5. Please visit our website ContactMagazine.com or feel free to contact us by phone or mail. If it weren't for the diversity of ideas and opinions, we’d all be driving the same car and flying the same plane. Such is the case with automobile engine conversions for experimental aircraft. Direct drive, belted, chain or geared PSRU; pistons or rotors; two or four-stroke; water-cooled or air-cooled; inline, vee or horizontallyopposed; pushrod or overhead-cam; carburetor or fuel injection are all valid choices and no single one is substantially more superior than another for every application. That being said, our cover story features plenty of opinions that are expressed as fact and are not necessarily right or wrong and should be viewed as a wellqualified opinion, based on actual successful experience, but an opinion none-the-less. On another note, same article, on page six there is a rather ambiguous statement made concerning “splitting the water tank” of the radiator. Unfortunately we didn’t have time nor space to go into full detail with this so we plan to write an entire article to be published in the next issue that should clarify the statement and hopefully become beneficial to all who read it. LETTERS I just received my latest copy of CONTACT magazine and read the CASE STUDY ONE of the first article about ECU. I now know almost nothing about whatever you were trying to tell me and have given up on the other case studies until I figure out what an ECU is. As a suggestion, why not spell out acronyms and then use the acronym for the rest of the article? Seems like a good way to get me to look forward to renewing my subscription. Kind regards, Earl from CA You are right Earl, sometimes when we are engrossed in what we do day-in and day-out, we forget that there may be new people joining in who may not be up to speed. But for your edification, an ECU is the computer in your car that senses all sorts of things and tells the engine how to behave. ECU stands for Engine Control Unit. The three case studies all describe the same anomaly; the engine shut down (went into “limp home” mode) to protect itself from the operator when it sensed a prolonged over-speed condition. I hope this helps enough for you to go back to the article(s) and enjoy them. My humble apologies, and I promise to not fall into the trap again. ~Pat www.ContactMagazine.com
Issue #83 has been dubbed the "CarterCopter issue" as all the articles in it are 100% Carter in nature. As a follow-up I'd like to present this press release. ~Pat Carter has designed a 6-7 place aircraft as a "Next Generation Business Air Vehicle" (BAV) for true point-to-point travel. This aircraft takes into account lessons learned from the original CarterCopter. The BAV, with a 2,000 HP (derated 2,500 HP) gas turbine engine will be fully pressurized, have a top speed between 370 & 405 mph (depending on altitude, and the accuracy of our drag estimates), and be capable of flying at 45,000 ft for 2,600 miles with reserves (best altitude for combination of speed, efficiency & range). The entire mast will tilt, allowing for a greater CG range and to keep the wings at their optimum angle of attack while the aircraft is flying at lower speeds where the rotor is providing more than its minimum lift. Note the restroom in the aft of the cabin which will enable true non-stop cross-country travel. This aircraft uses many of the same parts as used in the 4-place PAV, such as the rotor, wing, tilting mast, rotor head, auto mechanical rotor pitch control, prerotator drive including 90º gearbox, landing gear, horizontal stabilator mold, and autoflight controls. The 100" diameter propeller is the same as that used on the original CarterCopter except it will use four blades instead of two.
You gotta love their ingenuity and resourcefulness.
CONTACT! ISSUE 89 PAGE 21
Reprinted from issue #88.5
By Paul Lipps Paul Lipps wrote an excellent article entitled “How Fast Are You Really Going?” that we published in CONTACT! Magazine issue #80, back in September 2005. Paul has since revisited his work and has supplied us with this update. ~Pat In the previous article I wrote on this topic, I pointed out some of the errors that we have to contend with in trying to find out what our true airspeed is. In that article, I had the pilot fly in a circle to determine the wind direction and speed. Then once that was found, fly the plane on the GPS ground track into the wind, then with the wind, while recording the GPS groundspeed on these runs. TAS was obtained by adding them and dividing by two. Later I got to thinking about how much error there would be if you didn’t get the wind direction right on. So I set up a little mathematical model to determine how much the wind direction error would have to be for a one mph error for several different wind and airplane speeds. Hold on to your hat, you’re not going to believe what resulted! First, let’s look at how a wind will affect your groundspeed for a given ground track. Now for a little math lingo. A vector is a function, such as a wind, that has both a magnitude, its wind speed, and a direction, relative to some reference such as true north or magnetic north. Vectors can be resolved into two components at right angles to each other, forming a right triangle with the magnitude as the hypotenuse; this triangle has a side opposite to the angle and one adjacent to the angle. We call the opposite divided by the hypotenuse the “sine”, and the adjacent divided by the hypotenuse the “cosine”. For takeoff and landing, we learned all about how to compute the crosswind component of a surface wind. That wind had a magnitude, so many knots, and a direction relative to magnetic north. We took the direction, where it was coming from, and subtracted the runway heading. That moved the wind vector’s angle from magnetic-north-relative to runway-relative. (Note: surface winds are given relative to magnetic north, winds-aloft are given relative to true north.) Using a little trigonometry, or a whiz-wheel, we computed the crosswind component. From trigonometry, we would multiply the wind speed by the sine of the relative angle. That gave us the crosswind. Supposing we were landing on runway threezero (300°), and the wind was given as 20 kts at 330°. The runway-relative wind angle would be 330° minus 300° or 30°. Since the sine of 30° is 0.5, the crosswind would be 20 kts times 0.5 or 10 kts. We really didn’t care about the wind down the runway, but in this case it would be 20 kts times the cosine of 30°, or 17.3 kts (Fig. 1). Now in order to keep our plane going straight down the runway, we had to add a component of our forward speed off to the side where the wind was coming from. www.ContactMagazine.com
We did this by crabbing or pointing the plane in that direction, or by dropping the wing on the windward side to cause the plane to slip in that direction. When our sideward’s speed component equaled the crosswind, the one cancelled the other, and voila! We went straight down the runway. Just as we computed the crosswind component by using the sine function, we can reverse the process to determine the angle the plane had to fly to get those 10 kts. Since the sine is the opposite divided by the hypotenuse, then dividing the wind’s crosswind component by the plane’s speed would give the angle’s sine, which we then can obtain from a scientific calculator by using the inverse-sine function, sin-1, or looking it up in trig tables (Does anyone still have these?). If our speed was 65 kts, then the angle is sin-1 (10 kts/65 kts), 8.85°. Our airspeed toward the runway is 65 kts times cosine 8.85°, or 64.2 kts, and our groundspeed over the runway was 64.2 kts minus the wind’s 17.3 kts or 46.9 kts. Now let’s relate this situation to see what wind direction errors would give us a one mile per hour error in determining groundspeed, and from that, our true air speed, TAS. In other words, if the forecast wind turned out to be off by so many degrees, how much would that affect our ability to determine our TAS within 1 mph by using GPS groundspeed . What we will do is use this one mph error to determine the cosine of the airplane’s crab angle, and use this to get the angle’s sine. Multiplying this sine by the airplane’s speed will give us the crosswind component caused by the wind’s angle error. We will then divide the crosswind component by the wind speed to get the error-angle’s sine, then from that, determine the angle. ‘Sound complicated? Nah! 17.3 kts 20 kts
30°
Figure 1 First I’ll show an example, then I’ll generate a set of table values for a few selected airplane and wind speeds. Suppose our airplane has a TAS of 200 mph. This is directed off our desired track such that on the track we are flying 1 mph less or 199 mph. 199/200 is the cosine of 5.73°. 200 times sine (5.73°) is 19.97 mph. If the wind is 20 mph, then the error-angle sine is 19.97/20, or 87.2°! (See Fig. 2, opposite page.)
CONTACT! ISSUE 89 PAGE 22
Paul’s update, continued from page 24 Now get this; a 20 mph wind would have to be at almost a right angle to our course at 200 mph to give a 1 mph error! I told you that you might not believe the results. I didn’t! I went back and checked my math several times, and it kept coming out the same! Table 1 (below) gives the amount of wind-angle error which has to exist relative to the GPS ground track that we think is the wind direction that would give us a 1 mph error in groundspeed.
MPH
10
12
20
25
30
70
0.7*
52°
36°
28°
23°
100
0.5*
70°
45°
34°
28°
150
0.3*
0.8*
60°
44°
35°
200
0.3*
0.6*
87°
53°
42°
250
0.2*
0.5*
0.8*
63°
48°
300
0.2*
0.4*
0.7*
78°
55°
TAS WIND SPEED MPH TABLE 1. WIND ERROR ANGLE FOR 1 MPH ERROR
design while averaging 250 rpm less than in 2003, a 7.1% power decrease. For 2005, a four-blade prop was designed and built that restored the 250 rpm deficit. Because of some problems which were later determined to be in the fuel system, it was decided to go with the previous year’s three-blade. This same year saw Jeffrey Lo, in his new Miss Gianna biplane, flying an identical three-blade, with which he took first in qualifying at 237.403 mph. Phantom was being flown by Tom’s partner, Andrew Buehler, and qualified second at 232.71. Miss Gianna took the first heat at 224.043, and Phantom was third at 205.303. The positions changed on the second heat, with Phantom first at 216.018, followed by Miss Gianna at a close second at 214.392. The biplane Gold went to Phantom at 230.827, and Miss Gianna placed second at 220.443. Charlie Greer was flying his Formula 1 Miss B Haven (not in the biplane class) behind another ELIPPSE prop, and qualified third at 249.099, just behind David Hoover’s new Endeavor at 249.815. This prop was not well-matched to Charlie’s drag and power, and he was never able to get the design rpm.
* MAXIMUM ERROR MPH FOR 90° WIND
As you can see, the wind’s direction doesn’t affect us on a two-way, GPS TAS calibration run as much as we might have thought. That means we have a little more latitude when doing a TAS calibration run. We should still try to get everything as precise as we can to get the most accurate data. So now the easiest thing to do is first, call FSS at 1-800DONTGO and get the forecast winds and temperature for the altitude at which to test. Since that wind direction is relative to true north, this has to be corrected for magnetic variance to get the wind direction relative to magnetic north, because your GPS probably gives headings and ground tracks relative to magnetic north. Where I live on the West Coast, the variation is 14.5° E. With forecast winds of 15 Kts @ 285°, the magnetic direction is 270.5°. Climb to the desired altitude and use the GPS “track” to first fly the wind direction then its reciprocal. Note the GPS groundspeed and your indicated airspeed each way. Back on the ground, add the two groundspeeds and divide by two to get (TAS) true airspeed. Use the surface baro, test indicated altitude, and altitude temperature to get density altitude. Use this to correct IAS to instrument TAS. Compare this to the groundspeed TAS to determine instrument error, if any, such as ASI, pitot-static leaks, or static-port placement errors. 200 mph TAS 20 mph Wind @ 90°
199 mph GS
20 mph Wind @ 90°
199 mph GS
Figure 2
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Phantom with Paul’s four-blade prop. 2006 saw Phantom, piloted again by Tom Aberle and with the four-blade prop, setting a new qualifying record of 249.106 and winning the Gold race at an astounding, for biplanes, 251.958! Had they been using the course distance adjusted for the faster speeds of the Formula 1 racers, Phantom’s speed would have been 252.2 mph! Miss Gianna was no slouch either, qualifying at 241.136, and taking second in the Gold at 231.685.
VARI-PROP An agreement has been reached with Larry Morgan of Vari-Prop in which he will have ELIPPSE-designed blades made that will fit in his three and four-blade constantspeed and ground-adjustable hubs. This propeller combination is specifically designed for the Van’s RV-family of aircraft, accommodating 150 HP to 200 HP and speeds from 160 mph to 220 mph. Larry expects to have a propeller available for showing at the Golden West fly-in in California as well as at Oshkosh, and possibly at Arlington, Washington and COPPERSTATE in Arizona.
CONTACT! ISSUE 89 PAGE 23
Reprinted from issue #88.5 By Paul Lipps elippse@sbcglobal.net
MY PLANE SINCE ISSUE #77 Two changes have taken place on my plane. I modified the propeller tips to the designed shape of going to a point; this brought about an increase of static rpm from about 2190 rpm to about 2210 rpm, but I can’t say that it had a noticeable effect on cruise speed. The second, and oh so wonderful a modification, was the addition of a TruTrak heading autopilot and altitude hold. The Lancair has a fairly narrow-chord wing, so the available CG percentage change becomes only a very small change in distance. As a result, just reaching forward and placing my hand on the instrument panel would cause about a 200 fpm rate-of-descent, or putting my hands behind my head would cause about the same increase in rate of climb. It was really bad when I would reach across to pick up my chart of maps or a bottle from the seat beside me. I would raise my head and find the plane in a dive to the right. Now I just select my Garmin hand-held as my Nav source, set my altitude, and I’m on my way! This is really a benefit when I’m doing speed runs to calibrate my IAS and static ports, or just to see the effect of a change to reduce airframe drag. It becomes possible, under controlled conditions, to see a one mph change. I have a reprint of the article from the August 1983 Sport Aviation which gave the details of Dan Somer’s NLF(1)0215F “Eagle” airfoil used on my Lancair. This airfoil was designed to make use of flap reflex, raising the trailing edge up to reduce the airfoil’s camber and the position of its drag bucket relative to CL. From it I was able to approximate the desired reflex based on aircraft weight, TAS, and density altitude which determine the aircraft’s required CL. I did some experiments with reflex on a trip from Casper, Wyoming to Santa Maria, California, and was able to effect a 3 mph increase in going from 8 deg. To 6 deg., then a 3 mph drop from 6 deg. to 4 deg., and a 4 mph drop from 4 deg. to 2 deg. The other advantage was that as I reduced reflex, the body angle decreased, giving me more visibility over the nose.
Paul Lipps, as seen presenting a forum at the 2005 EAA Chapter One open house. the bolts with disastrous results! The Belleville washers, by having repeatable compression loading vs. deflection, lend themselves perfectly to the task of providing the best means to ascertain this compression through seeing and measuring that the washers have not been taken to their flat value.
BELLEVILLE WASHERS FOR PROP RETENTION The best that could be said about my use of these is for Pat to print, with permission of Vance Jacqua’s next-ofkin, the analysis that he performed. I have been using these washers with my propeller for at least three years, and the thing I note about them is that in removing them, it always takes several turns before the bolts will spin free. That is opposite the condition that is normally seen with prop bolts in that the torque is usually gone within ¼ to ½ turn. The other thing Vance brought out in his analysis is the amount of compression that should be achieved through torque on the bolts. He analyzes this both in terms of the required compression to achieve the necessary friction between the propeller hub and the crankshaft flange, as well as in terms of the crushing strength of various woods, and it can be seen from some of the torque specs I have seen, that from Vance’s analysis, some propellers are being spec’d at too high a value of torque. This could be crushing the wood and leaving the prop in a state where it could collapse further under loading, leading to the possibility of losing the torque on www.ContactMagazine.com
Photo courtesy Marc Zeitlin
Paul is not the only one to take advantage of the Belleville washer for prop retention. Cozy MKIV builder/flyer Marc Zeitlin has a successful experimental record with them. His installation is shown above.
RENO SUCCESSES 2004 was the banner year for Tom Aberle’s Phantom biplane, (see page 21) where he obtained a qualifying speed increase of 20 mph over 2003’s record-setting speed. This was done with an ELIPPSE three-blade prop SWITCH ON! Continued on page 23
CONTACT! ISSUE 89 PAGE 24