Last Update: 6/8/97
Web Author: Juan Jiménez
Copyright © 1997 by Juan Jiménez - ALL RIGHTS RESERVED
Beyond both the heated praise and the cold contempt for Jim Bede and his BD-5 lies the real, more fascinating story of the man, the plane and the concept
by John W. Olcott
JUST IMAGINE! Nearly 200 mph on 40 horsepower. Over 200 if a 55- or 70-hp engine is installed. Fully aerobatic. Great flying qualities. Less than $6 an hour to operate. All these good things plus the satisfaction of building your own aircraft for about $3,000. The BD-5 sounds fantastic.
Even before the plane first left the ground, thoughts of flying the sleek, bullet-shaped aircraft with its pusher prop stimulated the imagination of nearly everyone who had heard of the program. Thousands paid $5 for information kits; a smaller but still impressive number placed $200 deposits with Bede Aircraft for delivery positions and obligated themselves to pay the remaining purchase price in full when the first elements of the BD-5 kit were delivered. Others were skeptical of Bede's claims, and some were openly critical.
But claims and dreams aside, what is the BD-5 really like to fly? Will it meet the expectations of the 4,300 people who have embarked on the adventure of building the Micro and will it stimulate thousands more to enter the ranks of the BD-5 homebuilders? Or is Jim Bede's idea of a low-cost, high-performance sport aircraft an aberration, as some critics privately propose?
According to Les Berven, chief test pilot for Bede Aircraft, Inc., and, as of this writing, the only man to have flown the BD-5, the little single-seater is the closest thing to perfection a pilot can hope to experience. Even Berven's associates are amused by his euphoria after each test hop. Those who have seen him demonstrate the development test aircraft can appreciate the fun he must be having as he speedily darts about the sky doing rolls and loops or as he raises and lowers the gear in the blink of an eye. What fun it must be to have a responsive set of wings that seem to offer three-dimensional freedom, with hardly more than a caress of the stick.
It is easy to picture oneself devoting 600 to 800 hours building a BD-5. The money isn't much, particularly if a few friends join in on the fun. The old saw that good lines make good aerodynamics is sufficient proof to accept the claims of outstanding performance and exceptional handling qualities. The strong desire for a low-cost sport aircraft fires the imagination and makes the risks of embarking on a homebuilt aircraft program seem small compared to the rewards of flight in a BD-5.
Since 1967, Jim Bede has been transforming the BD-5 concept into reality. In that year, he and his chief design engineer, Paul Griffin, first generated the lines and preliminary performance estimates of his economical, high-performance sport aircraft. Work on the BD-5 project took a back seat to the BD-4, however, for Bede felt that the knowledge to be gained from the BD-4, a relatively conventional aircraft by Bede standards, was a necessary prerequisite to more sophisticated programs. The BD-4 proved there was a market for a well-designed homebuilt, and it demonstrated the viability of simple construction methods such as the Bede-patented panel-rib method of wing fabrication and the bolt-together fuselage design. In addition to providing cash flow, the BD-4 program also introduced Bede to the problems of estimating volume and satisfying needs for materials, but it did not prepare the company for anticipating the tremendous demand for the BD-5 when it was offered to the public in late 1970.
The first BD-5 information packets were sold in November 1970, and the first deposit for a delivery position was received on February 24, 1971. By August 1971, 800 orders with deposits had been taken, even though the first BD-5 prototype had yet to complete high-speed taxi tests. In comparison, since the BD-4 program started six years ago, about 600 kits have been sold. ON September 12, 1971, the BD-5 prototype, N500BD, configured with a V tail and powered by a 36-hp Polaris snowmobile engine, made its first flight in ground effect a few feet above Hutchinson Airport with Jim Bede at the controls. That outing identified a few problems in the carburetor mixture and the nosegear, and it was October before additional flights were attempted. Even so, the next time the BD-5 went airborne was somewhat unexpected. Delmer Hostetler, development manager for Bede Aircraft, was attempting some high-speed taxi runs so that Jim could observe tufts attached to the aircraft. Accelerating rapidly down the long runway at Hutchinson, with Bede's chase van in hot pursuit, the BD-5 suddenly hopped into the air, apparently to Hostetler's surprise. He handled the aircraft well, but it was obvious that the V-tailed plane suffered from poor directional stability. Hostetler applied a control input that induced a yawing oscillation. He quickly cut the power and landed in a slightly skewed attitude that damaged the nosegear. Bede went back to Newton, Kansas to design a more effective V tail.
After running through several new V-tail concepts, Bede decided on a conventional but highly swept horizontal tail design. His attempts to relocate the tail surfaces also convinced him that a fiberglass fuselage was not suited to the modifications that would be needed as the development program progressed. In order for the horizontal tail to be attached to the fuselage structure, the fiberglass outer shell required time-consuming rework. Furthermore, the cockpit area, which had been fashioned along the lines of the Schleicher AS-W15 sailplane, was too small. The large number of orders for the aircraft warranted the $30,000 investment in tooling required to produce shells for a more suitable metal fuselage. By December 1971, metal parts for the BD-5 fuselage were under development.
Between November 1971 and the first of the year, Bede developed a swept horizontal stabilizer and elevator system mounded near the bottom of the aft fuselage and a newly designed vertical tail. High-speed taxi tests in January revealed that the low tail produced an undesirable pitch change as the aircraft accelerated to takeoff speed. Tuft studies shows the problem to be caused by the induced flow produced by the propeller. Locating the horizontal tail six inches higher on the fuselage eliminated these adverse flow effects. Because a metal-fuselage version of the BD-5 was nearing completion and the fiberglass fuselage of N500BD was difficult to modify, Bede decided to forego any additional changes or flight testing on the original prototype and to devote all his attention to the all-metal N501BD. Also, N501BD was to be fitted with the Kiekhaefer engine that had been introduced to Bede during the EAA annual fly-in at Oshkosh, and he was anxious to try this American-made two-cycle powerplant.
It was also in the late fall of 1971 that Bede felt squeezed by the pressures of designing, testing and promoting that were required to make his company grow, so he started looking for a test pilot and additional engineering personnel. In December, Bede contacted Burt Rutan, who was a civilian stability-and-control engineer working with the U.S. Air Force at Edwards Air Force Base. Burt is a pilot and homebuilder. He designed a highly unconventional but apparently successful delta-wing aircraft. he is also a holder of an early BD-5 delivery position. Rutan joined Bede as director of development in March, 1972, and was followed shortly by Les Berven, also a civilian employee of the Air Force at Edwards and a qualified performance engineer. Rutan and Berven had worked together on many experimental flight-test programs.
Burt's first job after joining Bede Aircraft was to complete N501BD and start on a flight-test program that would parallel steps taken to certificate a factory-manufactured airplane. Supposedly, N501BD was within two weeks of its first flight when he arrived in March, but the plane didn't fly until July 11, 1972. Although the tail was higher on the fuselage and out of the troublesome prop-inflow effects, the swept design restricted the maximum effects of the elevator, so that the plane could not lift off at forward CG locations. An all-flying stabilator version of the swept tail was designed, but it had to be abandoned in favor of an unswept planform. Problems also developed between Bede and Kiekhaefer relating to minimum order size and financial commitments. Things were sorted out eventually, and N501BD started its flight tests with a 650-cc Hirth engine just as the summer of '72 commenced.
Nearly 16 months had elapsed between the first order for a BD-5 and the first circuit of the field, but the plane did fly and the development program was moving ahead.
Development programs are conducted because not all the answers to design problems can be determined analytically. An engineering team tries to anticipate and solve problems in the design phase, but it is not possible to foresee all the trouble areas; hence, the need for flight-tests. Longitudinal stability and control studies indicated that the elevator force needed to produce one G of acceleration for the BD-5 was only three-quarters of a pound! Typical values for World War II fighter aircraft were three to eight pounds per G. Test conducted by the Air Force indicated that a side-arm stick -- such as is used in the BD-5 -- can cut stick-force-per-G requirements almost by half; even so, the long wing BD-5B obviously would be too sensitive. The antiservo-tab gearing had to be increased to get more tab per degree of stabilator deflection, and the area of the servo tab was made 50 percent larger. After these changes, however, the stick force per G was increased only to a value of 2.5, which equates to a relatively light five pounds per G, based upon the Air Force studies. (The short-wing BD-5A experiences a higher stick-force gradient of three pounds per G because the ratio of stabilator area to wing area is larger.)
Not all the problems encountered in flight tests are as orderly as the stick-force situation. Bede was experiencing difficulties with the mixture requirements for his two-cycle powerplants. On the first flight of N501BD, Berven had to make several adjustments of the mixture control to prevent an overrich setting as the prop unloaded and the rpm increased during takeoff and initial climb. Much effort on the part of Hirth and the Walbro carburetor people was needed before these problems were sorted out. While the trouble may not have been directly related to carburetion, in August, after several flights designed to impress the FAA that the plane should receive permission to fly at Oshkosh, the engine seized. On its dead-stick landing, the airplane overran the runway, buckling the nosegear.
Mixture problems were the obvious cause of a more serious inflight engine failure in September 1972. During takeoff, as Berven was leaning, a brazed extension between the cable and the mixture-control arm broke. As a result, moving the pull-to-lean control did not have any effect, and the engine became rougher as the aircraft picked up speed. Thinking that he had overleaned the engine, Berven followed the acceptable procedure of reversing the action that apparently was causing the problem -- he enriched the mixture. Although the nature of the cable break did not make leaning possible. pushing the mixture control toward full rich did work and the engine coughed to a stop because of too much fuel and not enough air.
Berven was only a few hundred feet in the air with no options except to head for a convenient road. This time, the forced landing wiped out the undercarriage and caused some airframe damage. Bede engineers estimated it would take about three weeks to put N501BD back into flying shape, and it would only be two months before the next prototype, N502BD, would be flyable. The decision was made not to spend time fixing the damaged plane, particularly since the new gear-retraction system and several other features had been incorporated into N502BD, the latest version of the BD-5. So N501BD ended its flight days after about 30 hours of testing.
Test programs have a way of slipping, and it was March 26, 1973 before BD-5 flights resumed. N502BD was ready to go earlier, but during high-speed taxi tests, Berven noticed a vibration in the drive system at about 4,600 rpm. The previous two BD-5 aircraft had a variable speed drive that apparently gave no problems except for signs of some belt wear. But N502BD had a fixed belt drive system that developed a vibration problem in the long drive shaft between the propeller and the belt location. Vibration experts were called in, and extensive tests were run to isolate the problem. Finally, it was determined that the oscillating forces that are normally associated with a propeller rotating in an inclined flow field were exciting a bending-type vibration. Supporting the drive shaft with four bearings along its length instead of the original supports at each end eliminated the problem.
Since early April of this year, N502BD has experienced two other engine failures; one due to fuel starvation when a pinched fuel line prevented gas from flowing from one tank, and the other due to a seized engine. The latter failure was attributed to foreign matter that severely scored one cylinder in a newly installed powerplant. The engineers at Bede were encouraged by the fact that the fuel starvation didn't cause the engine to seize or damage the powerplant internally, even though the Hirth turned over without benefit of fuel and oil as the prop windmilled.
Although N502BD was flown for the public initially at Newton in 1972 and appeared this year at Reading and several other aviation gatherings, the development flight-test program is still not completed. Some aggravated stalls have been tried, but there have been no spin tests. A .25 scale, dynamically similar radio-controlled model of the BD-5 was built last winter specifically to learn more about the plane's spin characteristics, but the model aircraft engine that powered it quit during an initial practice run. The plane crashed before any spins were attempted. A second spin model was planned but was delayed.
Since its initial flight, the carburetion on N502BD has allowed rapid throttle movements from idle to full throttle and back to idle without mixture adjustment, and the first test hop to 7,500 feet was made with only minimal mixture adjustments. Still, work on the carburetor continued to occupy Bede and the Walbro engineers throughout the spring and summer, particularly as various engine mountings were examined. The kit version of the drive system also has not been finalized, although Bede feels confident that the basic design is frozen and that only endurance tests remain to be completed.
Test programs for conventional aircraft take time, and the BD-5, with its unique engine, drive system and tail-propeller location, can hardly be called conventional. Consequently, tow and a half years after the first BD-5 o4der was placed, the final configuration is still to be completed. Today's BD-5 differs from the original design in many ways. Compared to the originally-proposed BD-5 configuration, N502BD has a metal fuselage, a different canopy and cockpit dimensions, new horizontal and vertical tail designs, an oleo nosegear, a fiberglass leaf-spring main gear, a different gear-retraction system, plain flaps instead of the original split flaps, no spoilers, a fixed drive system and a fan-cooled Hirth engine. The aft end of the BD-5 had to be redesigned internally to accommodate the support features for the horizontal tail and drive system and to reduce the weight changes that resulted from these modifications. Unlike the initial N502BD configuration, the BD-5 manufactured by the homebuilder probably will have a vertically situated Hirth and the exhaust will be located on the bottom of the fuselage rather than on the side. Considering the past history of the BD-5 and other newly-designed aircraft, it would not be surprising to see other minor changes between the flight-test prototypes and the final BD-5 kit configuration. For example, aircraft can grow appendages such as fuselage strakes as a result of spin tests.
Jim Bede and his engineers are competent, talented people. They have squarely faced each problem as it has arisen. Fundamentally, that seems more important than the duration of the test program. Most of the developmental changes in the BD-5 were made as a result of experience gained from flight testing; this is a logical way to proceed for a small company with a small engineering staff and no wind-tunnel facilities. Also, flight testing and modifying the prototype vehicle is a typical development procedure for light-aircraft designers. The more test flights flown in the BD-5 now, the greater the chances that problems will be discovered by Bede rather than by the homebuilder.
Bede estimates that engines will be shipped to customers by September and that the BD-5's will be in the air by the end of the year. Presumably that means the flight-test program will also be completed by that time. Only one person, Les Berven, has flown the plane in up-and-away flight. Nonetheless, 4,300 have committed themselves to building the aircraft. More than half of these have already received materials and thus have paid the full purchase price. Fewer than two percent of those who placed orders have asked for their deposit money back. His followers believe that he will produce a plane worth the time, money and skill needed to build and fly the BD-5, and they appear willing to wait.
The reason given by Jim Bede for not allowing anyone but Berven to fly the BD-5 is the need to finish all development flight tests first. This seems reasonable, particularly when so much rides on the success of the aircraft. Why risk a mishap with it in the hands of someone outside the Bede organization, and why allow the plane to undergo critical flight examination before Bede is convinced that his child is exactly as he wants it? The stakes for Bede are large -- about $12,000,000 in BD-5 sales and back orders plus the anticipated 100 orders per month and related business the company expects when homebuilt BD-5's start to fly.
Considering the demand to finalize the BD-5, however, we cannot help but wonder if it might have been prudent to build one or two back-up planes for flight testing instead of spending shop time on the jet version of the BD-5 or on the BD-6. Bede insists that the BD-5 flight program proceeded as fast as possible considering the availability of engines and the pace at which homebuilders were completing various parts of the plane. Shop people and design engineers were put on these other programs only when the BD-5 did not occupy their time.
Considering what is known about the BD-5, it is possible to speculate what it might be like to fly. From talking to Les Berven, reading his commentaries, and watching the plane perform, it is easy to be caught up in the enthusiasm surrounding the aircraft. Undoubtedly, flying it will be exhilarating. The plane will be responsive, although the light control forces may cause the ham-fisted pilot to overcontrol. Small control pressures will result in larger G forces and airspeed changes than some pilots are used to; this could result in some pilot-induced oscillations, particularly in rough air, until the pilot is accustomed to the plane. Fun airports are often grass or dirt, but the small BD-5 wheels are more suited to hard-surface runways. The stalling speed is a little higher than Bede had hoped fore because the laminar-airflow airfoil seems to be experiencing some leading-edge separation at high angles of attack, which may be attributable to the relatively small size of the wing. Thus, CL max of 1.1 with flaps up and 1.45 with flaps down is not as high as it might be on a similar but larger airfoil. As a result, takeoff distances will be longer than originally estimated and the approach speed will be higher, particularly on the short-wing BD-5A. One wonders if the stall characteristics of the BD-5 laminar-flow wing will present problems for inexperienced pilots. Top speeds may be lower than Bede has projected. Already the original maximum speeds for all the BD-5 models have been reduced a little more than 10 percent, but it would not be surprising if the average homebuilt BD-5 fell somewhat short of the speeds listed in the performance specs. Laminar-flow airfoils can be affected by the condition of their surfaces, and even a small bug smashed on the leading edge can cause the flow to transition from laminar to higher-drag turbulent conditions. Differences in construction may also affect the performance of the individual BD-5's. Nevertheless, BD-5 speeds out to be very impressive.
Unusual as it may be, the BD-5 is not so unlike other aircraft that it will be immune to the hazards all planes and pilots face in flight. Some mishaps with it are bound to happen. Just flying any aircraft, flying the BD-5 will be a risk/reward relationship. You expose yourself to some risks for the rewards that come from building your own aircraft, from enjoying the thrills and excitement of a fun aircraft, and from being able to travel at speeds near 200 mph. The pilot accepts a similar risk/reward relationship when he flies any type of plane.
With the BD-5, the initial risk is in taking on a homebuilt project. When you embark upon building your own aircraft, no matter whether it is of your own design or a well-prepared kit, you are assuming the responsibilities of a manufacturer regarding the certification of that aircraft. Bede may design the airplane, flight-test it and ship you parts, but the responsibility for inspecting and accepting those parts, manufacturing the pieces into a plane and stating that your plane is worthy of flight is entirely yours. For example, the homebuilder is legally responsible for determining the gross weight and performance listed in the operating restrictions; Bede isn't. The FAA has a veto right and must inspect and approve your work, but you, not Bede or any other supplier who caters to the homebuilt market, must accept this responsibility.
Also, check your life insurance before you fly a homebuilt; most policies are not valid for experimental aircraft.
If you complete a homebuilt program, the length of time required probably is not a risk factor since, presumably, the task is fun. The longer fabrication takes, however, the greater will be the chance that your circumstances or interests will change and that the project will be abandoned. While there is a market for partially completed homebuilts, don't expect adequate compensation for your labor.
According to my homebuilder friends, Bede kits are fairly easy to build, and the company stands behind the quality of the packages it ships. If the homebuilder is having a problem, he is invited to call Newton for advice and consultation. Parts that do not meet the builder's approval are replaced if the builder so requests. Remember: You, not Bede, are the final inspector of all parts. According to the same sources, Bede also does more flight testing of its designs than do other suppliers of homebuilt kits.
The principal risk area with all homebuilt aircraft is flying them once they are built. Even assuming that the BD-5 is fully flight-tested according to FAA standards for a FAR 23 aircraft, the man who makes the first flight in the BD-5 assumes the job of a production test pilot, and he must maintain this posture until some time is put on the plane. Even when a certificated plane is put together by a major manufacturer, a qualified professional test pilot puts the first few hours on the plane. If the homebuilt design has not been thoroughly tested in its development stage -- and there is no FAA guarantee that it has been -- the homebuilder/pilot may find himself in the role of experimental test pilot if he intentionally or accidentally explores hitherto untried flight conditions.
There are rumors that the New Zealand distributor for the BD-5 may attempt to obtain a limited form of certification for the aircraft in his country. What effect that would have in the United States is not known. Bede's flight test program is fashioned along the lines of a normal certification procedure, and it is intended to be very complete. But even newly designed, conventional, standard-category aircraft manufactured by experienced companies occasionally offer some surprises as early models built up time in the hands of customers, so it seems reasonable to expect that the first-time homebuilder putting together a novel experimental aircraft is accepting a higher risk that does someone who buys and flies a certificated model that has been out for ten years. Certainly flying with the Hirth two-stroke engine, with its temperamental mixture and cooling requirements, will involve more of a risk than flying with a comparable four-cycle engine.
To balance the risks inherent in a homebuilt such as the BD-5, there are the rewards of building and then of flying something you have helped create. It must truly be a high point in one's flying experience. The exceptional performance and handling qualities Bede promises should place the BD-5 in a class by itself.
Will BD-5's by the thousands be built and safely flown? Will the rewards greatly outweigh the risks? Will the dreams of its builders be realized? It would be presumptuous to attempt answers to these questions, particularly without flying the airplane. It does seem to me, however, that the demand the public has demonstrated for the "micro" concept plus the capability and perseverance of the Bede team make the odds favor Bede and the BD-5.
When the BD-5 flew its demonstration flight at Reading last June, there was an almost universal reaction among those in attendance that the engine had the sound of a chain saw. If you watched carefully during that performance, you would have noticed a plume of blue smoke such as, when spied coming from early Saab automobiles, caused your mother to exclaim, "Look how that car is burning oil! Such a sin!"
The hard of the BD-5 beats with two strokes instead of the four that power virtually every other piston airplane.
Among motorcycle buffs, there used to be a rough rule of thumb that said: If the engine you want displaces fewer than 250cc, get a two-stroke; it displaces more, four-strokes are better. That was before the rising up of Kawasaki and Yamaha; the former company builds a 748cc bike with a two-stroke engine that offers acceleration on the order of an NHRA dragster; the latter makes a motocross bike of roughly 500cc displacement in one giant two-cycle cylinder that measures 95mm across the bore. The 250cc rule appears to have been made so that the Japanese could violate it.
There has long been another tacit but almost universal rule: Two-stroke engines have no business in airplanes. If you ask around, you'll find no one who can tell you who declared the rule valid, and Jim Bede obviously doesn't consider it binding.
Designers and aeronautical engineers who leaf through Bede brochures usually stop short at the cutaway view of the power layout -- engine, belts, pulleys and shafts -- and wonder aloud why Bede chose a setup that costs so much in weight-carrying ability.
It must have become almost immediately apparent as the BD-5's design progressed that the unique shape and layout of the aircraft would force the use of an exceptionally compact and powerful engine. If Bede shopped around even briefly, he must have come quickly to the conclusion that he would need a two-stroke engine.
He could have decreased the weight of the BD-5 very simply by abandoning the pusher prop and going to a tractor layout. In return for the useful-load gain, he would lose some of the longitudinal pitch stability that is inherent in a pusher arrangement (owing to certain propeller forces), but would not necessarily gain propeller efficiency. The old idea that tractor props are more efficient out there in clean air no longer seems the irrefutable maxim it once was. In any case, if he were to make such a change to save weight, the result wouldn't be a BD-5 but some other airplane. Few things may be sacred, but the BD-5's configuration appears to be one of them.
Given Bede's commitment to the present configuration and power layout, there is no other reciprocating powerplant that will produce the necessary horsepower and yet fit within the narrow confines of the BD-5 afterbody -- it must be a two-stroke.
There are recip engines that approach the two-stroke's power-to-weight ratio: The Porsche automobile engine has been developed to such a point; large-displacement four-stroke aircraft engines with geared props and turbocharging also produce as much horsepower as the number of pounds they weigh. Wankel engines could do it but for the fact that they require liquid cooling, which makes them too heavy. What Bede needed was an engine that produced as much horsepower as possible -- at least around 70 -- and weighing about 70 pounds.
Two-cycle engines produce such extraordinary power by replacing each intake stroke from a conventional four-cycle engine with another power stroke. Here's what happens inside the engine: Beginning with the moment of spark-plug firing, the two-stroke engine's piston travels downward, producing power to the crankshaft, as would any four-stroker. At the bottom of the stroke, the top of the piston slides past and uncovers a port in the cylinder that lets in a new air/fuel charge; an exhaust port has meanwhile been opened in a similar fashion, and the spent gases exit as the new charge enters. The crankshaft continues its rotation, and the piston begins another upward compression stroke, immediately covering the intake and exhaust ports at the lower end of the cylinder during its upward movement. Compression, power, compression, power. That's two strokes, or two cycles.
A lot happens beneath the piston in the crankcase simultaneously with events occurring in the cylinder. When the piston is nearly at the top of its upward travel, one of several types of valving arrangements allows the freshly mixed air/fuel charge to enter the crankcase. There's no oil in a two-stroke crankcase, so oil must be mixed with the fuel to provide a light oil film to protect bearings and other moving parts within the crankcase. If any one thing can be said to be the two-stroke engine's critical point, it's lubrication. Fail to get an adequate supply of oil to the surfaces opposed in friction and the engine will seize almost instantly. After the compression stroke is completed and the power stroke begins, the piston, in its downward travel, will cover the port to the crankcase. The crankcase is now sealed off as is a cylinder during compression; the piston therefore compresses the air/fuel mix within the crankcase just as if the mix were within a cylinder. as soon as the intake port between the crankcase and the cylinder is uncovered by the moving piston, the pressurized air/fuel mix injects itself, forcing out the exhaust gas. The piston continues traveling upward, creating within the crankcase a vacuum that, at the proper time, invites in a fresh charge of air/fuel from the carb. The result of all of this is twice as many power strokes per crankshaft revolution as in a four-stroke, which must waste an upward stroke pushing out exhaust gases and another downward stroke taking in a fresh charge. The two-stroke accomplishes both those tasks at the bottom of piston travel. In the bargain, the two-stroke does without overhead valves, cams and pushrods. It has fewer moving parts, and engine timing is more straightforward, consisting of direct mechanical events that are virtually impossible to throw out of adjustment.
Two-strokes have found fame and no small fortune in motorcycles, chain saws and now snowmobiles, but, because of the two-stroker's comparative lack of reliability, very few have appeared in airplanes. One engineer told me that the technology of two-cycle engines is roughly at the point occupied by conventional engines of the four-stroke variety back in the 1920's and '30's. While average four-cycle engines run for 2,000 hours without an overhaul, two-strokers are lucky to make it past 300.
The engines have two weak points that seem to hamper their reliability: lubrication and cooling. The lubrication problem is really a function of fuel metering, since the lubricant is mixed with the fuel in varying proportions. The drawback to that is, of course, that oil does not burn as completely as gasoline, and although two-cycle oils are specially blended, there seems to be no way to scavenge all the combustion products. Those that are left behind form a crust that must be removed periodically by decarbonizing the heads, a task all too familiar to two-stroke engine enthusiasts from motorcycle and snowmobile ranks. The problem is minimized by increasing the ratio of fuel to oil (from 25:1 in the old days to about 50:1 today) in two-cycle engines, but the risk of engine seizing goes up with the thinner mixtures.
Cooling is a problem simply because there is more heat being generated in a given time. One power stroke per revolution gives the metal less time to cool before it gets another dose of fire; four-cycle engines not only have more time between sparks, they also do not compress an air/fuel mix twice per stroke as the two-stroker does, and compression generates heat of its own.
The cooling problem is partially alleviated by using richer mixtures. This is yet another characteristic of two-strokes (besides their burning oil) that makes them unpopular with environmentalists. Aside from dirtying the air, they also gobble gas at so greedy a rate that range becomes a worry.
The single outstanding obstacle to the use of two-cycle engines in airplanes is that airplane engines must adapt to vast changes in altitude, and they must make such adjustments quickly and with relative ease. Four-stroke airplane engines solve altitude problems with the addition of a relatively simple mixture control to alter the flow of fuel at altitude, where the air is less dense. But what of the two-cycle engine's mixture of gas and oil? Can it be regulated to the precise degree that the engine seems to require? The answer is yes, probably. Carburetion continues to be a sticky area for most two-stroke applications, though -- two-stroke snowmobiles still into trouble in the mountains, for example -- and the engine's characteristics almost seem to demand two carburetors, one for high-rpm ranges and one for low. Carburetor settings in present engines seem to be extremely critical and the calibration must be just right in order to obtain efficient operation within the very narrow confines of the rpm range in which most two-strokes develop best power. Still, even with careful attention, two-stroke users may well experience spark-plug fouling in cold weather (therefore, at altitude) because of the oil's affinity for spark-plug electrodes in cold climes. They may further experience a certain amount of temperament in the little engines; settings that worked one day won't even produce a cough the next -- something like a change in humidity is enough to do it.
The problem of carburetion probably cannot be solved by an oil-metering arrangement alone, though some two-stroke enthusiasts swear that metering improves dependability; it also costs more. Whatever the ultimate solution to the carburetion and mixture problems may be, the cautious pilot is likely to want to err on the rich side, even at altitude, to avoid the threat of engine seizure from too little oil and too much heat.
In sum, you have to keep it clean, watch your fuel carefully -- mix it a little at a time so the gas doesn't evaporate and leave you with an oil-saturated fuel -- and stay well ahead of the 300-hour intervals between overhauls) some two-stroke mechanics decarbonize after only 200 hours) and have patience. If the two-stroke engine even begins to look promising, its application in the BD-5 is likely to lead to further experimentation with the little engines that can.
For a note of irony, page 28 of the FAA's Powerplant Handbook for airframe and powerplant mechanics says: "At the present time, the two-stroke-cycle engine is fast disappearing from the aviation scene and will not be discussed." Nonetheless, old two-stroke hands say the Bede setup looks to be a conservative one. The rpm range of 6,500 is not radical by comparison with experimental setups that have turned a two-stroke McCulloch go-kart engine in excess of 10,000 rpm. The rough-idle problem looms as more of an inconvenience than anything else, and both Bede and Hirth seem to have committed themselves to removing the few remaining drawbacks, even if they have to do it all by themselves. Look at it this way: Even if it doesn't work in your airplane, you'll still have a hell of a go-kart on your hands. -- George C. Larson
How is it that Jim Bede has not only selected a German two-stroke engine for his BD-5 but has also firmly committed himself to the purchase of no fewer than 5,000 of these high-revving and thirsty powerplants? They're not even aero engines, either, but straight conversions of snowmobile and industrial units, with no previous aviation applications. Hirth Motoren KG, which is building the engines for the BD-5 in its factory just outside of Stuttgart, has not been in the aviation business since its reestablishment after World War II, although the Hirth brothers had made quite a name for themselves in Europe before then as outstanding pilots and as designers and producers of high-quality lightplane engines. Wolf Hirth, one of Germany's pioneer soaring pilots, died only four or five years ago, and thereby severed the remaining family link with the present company.
Since its return in 1951, the Hirth company has specialized in two-stroke engines for lawn mowers and trucks, but Hirth's real technological and commercial breakthrough came with the emergence of the snowmobile a few years back. Before then, Hirth had had no real demand for high-performance two-stroke engines; within about three years, the power output in relation to cylinder capacity of Hirth engines doubled and even tripled. The company came up with a range of compact single-, twin- and three-cylinder air-cooled, two-stroke engines, all well under 1,000-cc (61 cubic inches) capacity but with outputs between 19 and 82 hp, and power-to-weight ratios of around one and a half pounds or less per horsepower. This is at least as good as certain lightplane engines.
The success of Hirth's new engines is indicated by sales, which, in 1969, reached 140,000 in various industrial applications. That figure proved to be a peak that has since leveled off to a bit less than half this total annually. Still, it is a very sizable market, on any count, and represents a vast background of operating experience.
Not so surprising, then, that Jim Bede picked the Hirth snowmobile engines as powerplants for the BD-5 (after first trying an American two-stroke). The BD-5 Micro is appropriately named, for there are few engines that will fit in the narrow rear fuselage and fewer still with installed weights of less than the acceptable maximum of 100 lbs. The two-cylinder Hirth engine is therefore fundamental to the design of the BD-5, but even this 650-cc unit started off tilted on its side in the prototype installation in order to fit within the slim rear fuselage cone.. Most of the test-flying has been done in this form. In the prototype BD-5, the engine develops 55 hp at 6,750 rpm, and Jim Bede has to use a toothed-belt reduction gear to get acceptable propeller speeds. The pusher prop is mounted on the end of a massive light alloy shaft, the other end of which has a pulley that mates with the toothed belt.
Hirth engines have always had a reputation for quality, with five-bearing crankshafts and a crankcase thicker that most, so surprisingly few changes are needed for aircraft use. The standard engine comes complete with integral cylinder air-guide shrouds and an axial cooling fan on the front cover, which makes it especially suitable for the BD-5 pusher installation. Only the pressure diaphragm carburetor, projecting way out from the right-hand side of the engine, has presented an accommodation problem. A tilted engine installation was devised to cope with that, and it has taken Hirth many months to come up with a new intake manifold that will fit inside the BD-5's slim rear fuselage. The engine compartment is a sealed box with an air intake below, so no carburetor heater is considered necessary. A large-diameter pipe ducts the hot air from the rear of the cylinder shroud through the rear bulkhead alongside the exhaust muffler, which it helps to keep cool.
After the initial flight trials with the standard Hirth engine, Bede approached the German company last year through its research laboratory in Detroit for some help with powerplant development. Hirth's reaction was initially cool, with considerable skepticism over the estimates for the potential market. But a study of Bede's impressive engineering setup and the reaction to the BD-5 at various airshows finally convinced the German company to invest in the engine program.
One of its first steps was to develop a dual ignition system. This meant designing a new cylinder head with twin spark plugs and replacing the standard flywheel magneto ignition with a capacitor-discharge system that had few moving parts and no points. The Bosch company delivered to Hirth the first capacitor-ignition system last February, and bench-running was undertaken before shipment of the first flight unit to Bede a few months later. By early June, a second prototype BD-5 had flown about 15 hours, apparently with satisfactory results, except that cylinder-head temperatures ran 40 to 50 degrees higher than Bede would have liked; this could mean another change in head design. The dual-ignition engine is mounted in the upright position in the BD-5; that has at least simplified the problems of installation, power transfer, vibration control and mixture induction.
Hirth has made a few other minor changes in the engine to convert it to aircraft use, but the company has also gone one step farther by developing a more powerful engine especially for the BD-5, again mostly at its own expense; Bede has paid for the tooling. The new powerplant is similar to the original but has bigger cylinders and pistons that increase its capacity to 720-cc and its power output to 65 or 70 hp at around 6,500 rpm; it weighs about 82 pounds. Most of the 5,000 engines ordered from Hirth by Bede will apparently be the 720-cc version. Some 650's and smaller, down to 400-cc and about 40 hp, are being offered by Bede and Hirth, but Bede's latest newsletter plays down all but the biggest.
Hirth and Bede hope that by the end of this year, the dual-ignition engines will be certificated for normal aircraft use in both the U.S. and Germany. Hirth has already obtained such certification for a very different two-stroke 25-hp four-cylinder sailplane auxiliary engine it produced. In the meantime, the BD-5 engines can be operated within the experimental category in the U.S. Despite the high compression rations (10.2:1) of these engines, they are designed to run on regular automobile gasoline and oil on a 25:1 mix fed by a single pump. Special pistons have been tried successfully on the 720-cc engine so that it can operate on 100-octane fuel. Hirth also tried casting crankcases and other parts for these engines in magnesium to save eight or ten pounds, but wear proved excessive, so aluminum has been retained for the production powerplants.
First production deliveries of the Hirth engines to meet the Bede contract had not yet started by mid-1973, pending a final solution of the intake- and exhaust-manifold problems; most parts were being held by the German company, which was gearing up to ship 250 engines per week to Bede. All of the engines in the present contract will be built in Germany, although Hirth has been considering establishing a production facility in North America -- probably in Canada.
In the course of a visit to the Hirth factory at Benningen, on the River Neckar near Stuttgart, I saw one of the new 720-cc engines on the test-bed, where about 100 hours' running of the complete powerplant had been accumulated. In operation, the Hirth unit sounds like an outsize model-airplane engine as it howled up to 7,000 rpm. Two-stroke engines are characteristically smooth at high rpm, but at lower speeds, they tend to run rough as they begin to four- and even eight-stroke, so it is difficult to get them to idle satisfactorily below 1,800 to 2,000 rpm. On the bench, closing the throttle dropped the revs initially to about 1,200, from where they gradually fell back to about 800 rpm, with the aforementioned erratic firing sequences. Since these engines have geared-prop drives, their idling peculiarities many not be too important, although there were reports that high residual thrusts and low rpm problems were encountered by the prototype BD-5.
In fact, the optimum power range of most two-strokers covers a spread of only about 1,500 rpm with fixed carburetor settings; the BD-5 has a manual mixture control, however. "To be safe," says Hirth, "we are running a little on the rich side with the Bede engines." Jim Bede confirms the existence of rich-mixture problems during development flying. It is presumably difficult to lean the carburetor settings any further because of the high cylinder-head temperatures -- about 230°C indicated with the engine steady at 4,000 rpm on the test-bed.
According to Bede, the BD-5 engines have a specific fuel consumption of about 0.7/pounds/hp/hour -- worse than most small turboprops at sea level. In practical terms, this means using between 4.5 and 5.5 gallons per hours with the 650- and 720-cc engines, which would be tolerable if the BD-5 achieves its design performance.
From Hirth's point of view, interest in the BD-5 has been strong enough to establish general aviation as a good future market, and to encourage the company to look into special aircraft projects. Hirth has already undertaken long-term studies to reduce the fuel-consumption penalties of high-performance two-stroke engines, and it is looking into fuel injection or a reed-valve system instead of conventional carburetion. Another problem that needs solving by research is the low TBO's of two-stroke engines, pegged by Hirth at only 300 hours to start with (on the basis of past experience with industrial units). One good thing about two-strokes, however, is that their simplicity helps keep overhaul costs to a minimum.
Initial purchase costs are also low, although there is a big difference between the standard 650-cc snowmobile engine at about $280 ex-factory, and the aircraft version, with its light-alloy cylinder shrouds, shielded and transistorized dual ignition, electric instead of pull starter and modified exhaust and inlet manifolds, at $480. Still, the latter price is pretty hard to beat by U.S. aircraft standards, and who is to say that the remaining problems of two-stroke engines can't be overcome by Bede and Hirth?
Hirth is certainly optimistic enough to continue its own research into projects for a future line of light aircraft engines -- two-stroke, of course -- with four cylinders yielding outputs of around 100 to 120 hp -- for that it hopes will be ever more appealing two-seat lightplanes. The company is already hawking drawings of the new engines, which it is prepared to translate into sample hardware, given sufficient encouragement. The Hirth creed is that the new generation of two-stroke engines will replace the less-efficient, very expensive four-stroke powerplants.
Even without these developments, however, Hirth is confident that it will at least double sales of its 720-cc converted aero engine through a follow-up to the BD-5. The Micro may not prove to be everyone's choice of an airplane, but for those people not ready for a BD-5, the intimate Bede is about to launch the BD-6; another single-seater, but this time a high-wing. The BD-6 will be a homebuilt with the Hirth 720 in a conventional nose installation, with neither cooling shroud or blower. The prototype should fly soon. Hirth has its sights on selling at least another 5,000 engines in the first year of BD-6 marketing, which just proves that Jim Bede is not the only optimist on the homebuilt horizon. -- John Fricker
Building the Bede may take you longer than you think -- it may even become a way of life.
The BD-5 is advertised in non-aviation publications as well as those concerned with flying as being sort of "everyman's airplane": easy to construct at home and easy to fly. This, in combination with its relatively low cost, makes it very attractive to a wide range of people who normally wouldn't consider homebuilding. The high performance and sexy appearance of the airplane have also helped to sell literally thousands of BD-5 kits, although so far only factory prototypes have actually flown.
Some concern has been expressed about the ease -- or lack of it -- with which a BD-5 can be assembled. With this in mind, Flying obtained some BD-5 plans and instructions and canvassed various experienced aircraft builders and suppliers for their opinions.
Among them were Ernie and Les Schweizer, whose sailplane factory is an outgrowth of early homebuilding, and who also have considerable experience preparing and marketing aircraft kits; Dave Thurston, designer and initial builder of the Teal amphibian; John Thorp, designer and builder of the popular high-performance T-18 homebuilt; and Flying's Peter Garrison, whose Melmoth project has made him knowledgeable about homebuilding's pitfalls and pleasures.
All of these people were impressed with the presentation of the plans. The large number of sets sold has enabled Bede to provide very clear drawings, well printed on heavy white paper. The set of plans -- or "Construction Profile" -- comes in a logical sequence of subassemblies, starting with the fuselage and ostensibly increasing gradually in complexity, enabling the builder to learn techniques as he goes along. Each subassembly chapter is headed by a list of materials and parts for that subassembly as well as a set of photos defining various bits of hardware or tools ("...this is a Cleco") or their uses ("...fastening the parts together with Clecos").
As far as tools are concerned, it is clear that it will take more than "a few simple tools" to build a BD-5. A well-equipped home workshop will certainly have the nucleus of the tool requirement, but the Bede "minimum tools" list does not include such specialized goodies as a complete drill set; one dozen C-clamps; sets of open, box and socket wrenches; 100-degree flaring tool; Nicopress cable-swedge squeezing tool; dimpling dies; hole saws; cylindrical and tree-radius rotary cutters; blind-rivet gun; Cleco pliers; and 150 Clecos in two sizes.
Blind rivets are those that can be set from the head side alone, rather than having to be hammered against a backstop, or bucking bar, on the other side of the work; instead, the far end of the rivet is spread by a shank pulled through the head end of the hollow rivet. A special tool -- the blind rivet gun noted above -- is required to do this pulling, by hand or air power.
Dimpling dies are used to form small depressions in aircraft skins to receive the heads of flush rivets, since these skins are usually too thin to be countersunk. They are usually used on the business end of a conventional rivet gun and bucked against a matching set of female dies; in the BD-5, male and female dies are assembled (on opposite ends of the workpiece) along a nail and are pulled together by the blind rivet gun.
The infamous Cleco deserves mention, both because of its importance and because at least 150 of them are needed; it is the ideal means of fastening metal parts together while they are being riveted. For all practical purposes, it's sort of a spring-loaded rivet which, when held in special Cleco pliers; becomes skinny enough to fit through a rivet hole. When the pliers are released, the Cleco expands (so that it can't pull out of the hole) and shortens, pulling the metal parts together just as a rivet would. Grasping it with the pliers again reverses the process to enable removal. Large assemblies require goodly numbers of the little devils to hold them together, and Clecos are not particularly cheap.
They present other problems, too; if improperly grasped in the pliers, their powerful springs make them suddenly whiz away into the distance or into some fragile object. Their usefulness, high cost and small size subject them to easy pilferage by other homebuilders who come to visit. A homebuilder who might cheerfully permit you to make free with his wife or daughter will turn homicidal if he sees you cast so much as a sidelong glance at his rusty coffee can filled with Clecos. Finally, just as wire coat hangers will multiply spontaneously if left in a dark hall closet, a reverse process causes Clecos to decrease in number if unobserved. A novel theory suggests that the metal of Clecos evaporates into thin air, only to condense as coat hangers.
The fascinating objects described above are merely part of the minimum tool list; a check with local stores reveals that this would come to well over $200. The "optional tools" section, featuring tools to make construction easier, includes saber saws, drill presses, automatic stop countersinks, a powered hacksaw, a band saw, a table brake, a torque wrench and more Clecos.
Once all the tools have been procures and a suitable workspace arranged for (one brave soul is building a BD-5 in a Brooklyn apartment, but something along the lines of a garage is more feasible), we can think of going on to the actual construction of the BD-5. The plans provide two kinds of information drawings; either life-size or scale, and either plan view or perspective; and narrative instructions in a step-by-step order. Several of those who looked at the plans commented that while the attention to detail and idiot-proof description of the narrative version was commendable, they would have liked to see more basic how-to instruction rather than simply "Step 48: Make the part shown in (6R) out of .0125" 2024-T3 aluminum." Almost all the experts also noted a lack of detailed dimensional information. Apparently, since many of the drawings are life-size to allow either direct measurement or tracing to make templates, Bede's draftsmen thought it unnecessary to include every dimension.
Not all of the plans concern construction of BD-5 parts themselves. Some describe the construction of fixtures and form blocks that will be used to make airplane parts. This can represent plenty of work in itself, and it seems that a logical outgrowth of this as well as of the tool costs will be that several builders will pool their resources. A Bede spokesman has indicated that Bede dealers may become involved in supporting homebuilders in some manner, possibly even providing more elaborate jigging than that can be called for in the plans and renting shop space and tools. Based on the number of kits sold, this could be quite a tidy satellite business in itself.
Some of the parts come pre-formed, although few enough not to violate the condition that at least 51 percent of the aircraft be amateur-built to be certified as such. All the wing ribs are pre-formed, as are the fuselage-shell parts involving compound curves.
Early construction estimates were unreasonably low -- 600 to 800 hours. Most of the experts agree, however, that an inexperienced homebuilder of good mechanical aptitude could construct a BD-5 in 1,000 hours, it all went well. -- Peter Lert
Call it savvy or folly, Bede has come up with an intriguing approach to low-cost sport planes: Let the consumer carry the ball.
Bede Aircraft Incorporated is a monument to Jim Bede's perceptiveness as a businessman. He founded the firm about six years ago to satisfy the need for low-cost, personal/sport aircraft that he felt were not being met by the aviation industry. The marketing success of the BD-5 thus far seems to be demonstrating the wisdom of his strategy.
Bede thinks that the general-aviation manufacturers have become experts in developing "company" aircraft, but have neglected the inexpensive personal sport plane. This, he feels, is related directly to the manufacturing process. Normal aircraft-production techniques involve extensive custom and precision work and therefore require a large labor input. The price of small aircraft, therefore, is high compared to the cost of the materials used to build them. Bede claims that when all the economic factors, such as the demand for a product in relation to its selling price, are considered, it is more profitable for manufacturers to build large aircraft.
Bede aircraft overcomes the labor-cost problem by letting the purchaser of a BD-4 or -5 supply his own labor. Bede has the materials mass-produced by suppliers, and then packages them into kits at his warehouse in Newton, Kansas for shipment to his customers. Instead of being a high-cost item, the labor required to fabricate the plane becomes a recreational item, part of the reason for buying the product in the first place. Bede bypasses most of the engineering and tooling costs on major hardware items, such as the engine, by using components which are mass-produced for existing markets. His operations are strictly limited to designing airplanes, warehousing materials, packaging kits, marketing and distribution. Bede manufactures nothing.
Since Bede aircraft is not required to certificate either the BD-5 or the kits from which the homebuilder fabricates the plane, considerable administrative costs are eliminated. Bede Aircraft is conducting extensive ground and flight testing that duplicates what would be required for Part 23 certification, but the company has chosen to do this voluntarily, and it will not provide the FAA with any of the detailed documentation that is required for a production aircraft. In fact, the FAA has no regulatory authority over Bede Aircraft, since the operation, from a legal standpoint, is a warehousing and distribution business and not a manufacturing facility. Bede is not required to hold a BD-5 type certificate, or a production certificate or parts-manufacturing approval. The FAA's legal role relates only to people who build and request permission to fly the BD-5.
By catering to people willing to build their own airplanes, Bede lessens the impact of another major and potentially costly headache that faces the aviation industry -- product liability. Because Bede Aircraft is only a supplier of materials, it is the BD-5 builder's responsibility to inspect those materials for acceptability when he receives them. If they are not satisfactory, Bede stands ready and willing to replace them. The FAA also serves as the final inspector of the workmanship that goes into the finished aircraft. While Bede is not relieved of responsibilities with respect to the BD-5 design, he is several steps removed from the obligations of a manufacturer who produces and sells a certificated aircraft. Nevertheless, Bede is going to considerable effort in his flight test program to ensure that his design is complete and that his representation of the BD-5 is accurate. Still, even though Bede also inspects the materials he receives from his suppliers in much the same way as do the "big three," the homebuilder must take the lion's share of responsibility for the final product.
It thus appears that Jim Bede has produced a workable solution to three of the major problems facing the lightplane industry. Bede Aircraft seemingly has a way of "mass-producing" aircraft, a means of lessening the cost impact of FAA certification and a scheme for staying far away from the specter of product liability. These concepts allow Bede flexibility in the implementation of his designs, and they make the cost/benefit relationship of his products very attractive to the man who is willing to "roll his own."
According to Bede, the light-aircraft manufacturing establishment dismissed the advantages of a BD-5-like program because no one thought there was a large market for homebuilts, particularly single-seat models. Now, 4,300 orders later, Bede likens the industry's misreading of the demand to the automotive establishment's belief that Volkswagen's would not sell because they looked unusual. Bede is offering the public a fun aircraft, one that some pilots apparently feel will give them enjoyment and personal utility at a price within luxury-spending budgets. They seem turned on by the prospects of building a flying machine with such unique characteristics, so much so that they are willing to give Bede Aircraft their money even before the concept becomes a finalized BD-5 design.
It is good for those who ordered Micro kits as well as for Bede Aircraft that even before the plane has completed its test program, sales of the BD-5 are running over four times the initial projection of 1,000 units. Bede now estimates that between 90 and 110 orders a month should roll in once homebuilt 5's are operational. The large number of orders and the prospects for more have given Bede noticeable clout with potential suppliers such as Hirth, which will furnish the engine, and have made possible expenditures for additional tooling and high-quality construction plans. If the total market for the BD-5's had been only 1,000 units, Bede would not have been willing to spend the nearly $40,000 for dies, and the fuselage would have been fiberglass. Also, if the demand had been smaller, he might not have been able to attract the engineering and management talent that now forms an important part of the Bede team.
As pressures for his product and his time have grown, Jim Bede has wisely recognized the need for additional key personnel. In the spring of 1972, he added two highly qualified and enthusiastic engineers, Burt Rutan and Les Berven, as director of development and chief flight-test pilot, respectively. In January 1973, Herb Sawinski resigned as general sales manager of Bendix Avionics Division to assist Bede, initially as sales manager and now as general manager. Bede Aircraft presently employs about 80 people, many of whom recently left good jobs elsewhere in aviation or marketing endeavors to get aboard the Bede bandwagon.
Particularly since Sawinski joined Bede, a more businesslike atmosphere prevails at the company. There appears to be more planning and accountability behind various company moves; there is added emphasis on realistic budgets; people have better job descriptions; related functions have been assigned to newly organized departments. Purchasing, for example, is now handled by a special department; previously each of seven men scattered about the company was doing his own ordering as his individual needs arose. It is not clear who was responsible, but several of the 14 planes -- which have included a Turbo Baron and a regular Baron -- Bede Aircraft owns or used for travel and various engineering endeavors have been sold. Sawinski supports and complements Bede's position as president of the firm and thus gives him more time to devote to engineering and long-range planning.
Bede's long-range plans naturally include serving the needs of the dedicated aviation enthusiast. In addition, he has his eye on the potentially large market that may exist in that vast group of people who become disenchanted with flying and drop out of active participation. There are estimates that give out of every six students leave the scene before they obtain a private license and fly more than 100 hours. Bede feels that many budding pilots fall by the wayside because flying is more expensive and less fun than they had hoped. If one of every five dropouts could be enticed into staying with aviation, the potential market for aircraft and related products would double. Perhaps the BD-5 will not be purchased by the student who is considering giving up aviation, but Bede speculates that the prospects of working up to an exciting aircraft like the 5 may encourage some to keep flying. Various low-cost personal sportplanes, like the BD-6 and other aircraft too new to have a name, are planned by Bede specifically to appeal to a market not reached by the aircraft manufacturing establishment.
Bede's plans are always bold; he is constantly brimming with optimism. He is an aviation enthusiast of the first magnitude, and he possesses an innovative, creative mind. Occasionally, however, he expresses his novel ideas somewhat prematurely, before all the details have been worked out. This last characteristic is a bit repugnant to some of the more conservative types in aviation, but it is accepted by his followers as providing opportunities to learn what he may offer next. There seems to be a large segment of the aviation-minded public that wants what Bede says he can produce, and these people appear willing to forgive the long delays and somewhat exaggerated claims that are often associated with Bede programs.
Bede insists that many who placed early orders for BD-5 kits would have loaned him the money they committed to the program if he had requested it -- that is how much they wanted what he had to offer. Whether or not that is a realistic assessment of the faith Bede followers place in him is not important. What is relevant is that his early and possibly premature trumpeting of the BD-5 did excite much enthusiasm and did provide him with a market acceptance upon which he has literally capitalized.
What will happen if Bede cannot develop a successful BD-5? It is hard to say in legal terms. The purchase agreement does not commit Bede to deliver all the pieces of the airplane by any specific date, although legal action would probably be taken in many quarters if engine deliveries, for example, dragged on indefinitely. Once a person has received 30-days notice that his first BD-5 parts are being shipped, he is committed to pay the purchase price in full; up to that point he can request his deposit back. Bede Aircraft places the total purchase price on the books as a liability owed to a buyer, and then reduces that liability as parts are shipped. Monies are released to the company as homebuilders receive their BD-5 wings, fuselages and other parts, so the customer's total purchase money doesn't really exist in the form of dollars that could be returned to him if the program suddenly folded.
When questioned about his alternatives if, for some reason, the BD-5 cannot be developed successfully, buoyant Jim Bede smiles and says that the BD-2 could be made flyable and that there is nothing to prevent him from taking it halfway round the world. Then he becomes more serious. He is sure that a BD-5 failure is not possible because he and his team have cleared all the major engineering hurdles and are now heading down the final stretch at full speed. He insists that the people who placed orders will receive all their parts and will be satisfied, and he quickly adds that he has never cheated anyone or had a creditor sue him and that all those who placed deposits for BD-1's got their money back. He points out that while he has not made good on his round-the-world projection yet, he did fly the BD-2 a record-setting distance. And he is quite willing to tell his side of the BD-1 story, including how things might have been different.
Bede concludes his defense by observing that he learned a lot from his experiences with Bede Aviation (later American Aviation and now Grumman-American); first, that he is a better designer than he is a lawyer, and second, that he should not involve outsiders as stockholders in his firm. Bede Aircraft was formed and capitalized by Jim and his father, a wealthy retired businessman who was a successful manufacturer of paint-spray equipment. The firm has no other stockholders. Jim considers those who placed orders for the BD-5 to be pioneers with trust in his capabilities, but he does not put them in the risk category of stockholders. He is confident that Bede Aircraft has the personnel, facilities and flexibility to finish up the BD-5 program and move ahead in many areas dealing with personal aircraft.
Great things are planned. There are the BD-6, the BD-5J, continued success with the BD-4, a small solid-state computer that will replace the E-6B and things so exciting that Bede will only allude to them. "We will announce big things by September, maybe sooner," he says. "Our skunk works has major design programs and minor design programs. When things get bogged down on the tough jobs, we take a breather and refresh our spirits working on the easier tasks. It works great! We have started a small fire here, and we will light up a few eyes! Bede Aircraft will succeed in an area that has been put down. We will give the aviation public a reason for optimism, and we will show the industry much innovation in the next 10 to 15 years."
As for the outcome of the BD-5 program, that is complete as far as design is concerned; according to Bede, only some details remain. But many in the aviation world are anxiously awaiting news that the "details" have been completed and that the BD-5 meets expectations. Bede Aircraft is truly a monument to Jim Bede and his skills, but the inscription may depend upon the BD-5. -- John W. Olcott
In case you're already bored with the idea of a 200 mph single-seater powered by a snowmobile engine, Bede and his merry men have already built and flown a jet-powered version of the BD-5. The BD-5J is essentially a beefed-up version of the straight 5, with a tiny French Sermel TRS 18 engine in place of the two-cylinder, two-stroke Hirth.
The jet exhaust runs aft exactly where the propeller shaft fits in the recip BD-5's, and issues at what would otherwise be the location of the prop hub. The tailpipe is capped by what looks for all the world like a thrust reverser -- a pair of metal clamshells that clap together most impressively when a manual toggle in the cockpit is pulled. They're not reversers but "attenuators," however; since jets put out a respectable amount of thrust even at what is for them "idle," the Bede people explain with much glee that the BD-5J would fly at 140 knots in idle thrust without the thrust attenuators to deflect the exhaust.
The engine is a wee thing -- it's the one used in the Caproni A-21J jet sailplane -- but it pumps out 200 pounds of thrust out of its 66 pounds dry weight. If that doesn't sound like much, it's equivalent to about 186 hp at the BD-5J's estimated maximum speed of 305 knots.
The BD-5J pilot will be one busy boy, since he'll have to be IFR in positive control airspace to go above 18,000 feet. (Can you imagine rummaging through a Jeep bag inside a BD-5 cockpit? You'd be better off memorizing the charts.) Questions also arise as to exactly what the purpose of the machine is. At $20,000 to $25,000 for a BD-5J kit, it's not exactly an impulse purchase, yet it borders on being one of the world's most expensive toys. Is it for doing aerobatics -- at FL 240, with loops so large they'd constitute a cross country for a Pitts Special? Is it for making speedy business trips -- with baggage room for a large toothbrush and a small notepad?
The truth of the matter may well be it's solely for getting attention -- for Jim Bede. With his inimitable flair for showmanship and for divining what the sports-aviation community "wants," Bede may have built his little jet not only as a lark -- a knee-slapping, wait'll-they-see-this-mother aberration to tickle the fantasies of his own engineers -- but as another attention-getting firecracker that he has ignited at just the right time to keep the public's interest high.
(Note: This article is based on FAR regulations that were in place in 1973. While the general nature of the article remains relevant, the specific rules have changed significantly since then. Refer to a current edition of the FAR's, the AVSIG forum on CompuServe (GO AVSIG) or the rec.aviation.homebuilt newsgroup for the current information.)
Unlike other things you may build in your garage, backyard turkey coop or living room, the BD-5 you may be working on cannot be assembled and operated freely, without a second thought. All airplanes in the United States must be certificated by the Federal Aviation Administration under regulations that can impose limitations of various kinds upon their operation. All homebuilts are so affected.
Whatever you may have heard or read, the FAA has not declared the BD-5 airworthy -- that is, this particular model of aircraft has not been certificated. In fact, the FAA has no legal responsibility to check out the quality of the kit Bede Aircraft sends you. Its legal responsibility lies in inspecting the airplane you build and in declaring it "airworthy" or not, according to whether you've met the Government's standards for a sound and reasonable structure, a satisfactorily performing engine and an absence of hazardous characteristics. The rules governing these conditions are strict.
Practically speaking, there is a gentleman's agreement between Bede and the FAA for its inspectors to drop in now and then on the company's BD-5 operation to see how it is going. Still, Bede Aircraft, for all the looking the FAAmen can do, holds no FAA certificate --such as a type certificate, production certificate or parts-manufacturer approval -- that is good for every BD-5. Bede is essentially a supplier of parts. You, by the dexterity of your hands, the work of your tools and the sweat of your brow, are the actual manufacturer. Furthermore, homebuilt BD-5's can be certificated only as "Experimental -- Amateur Built," which has a direct bearing on the airplane's legal operation.
This is not to say that the FAA necessarily distrusts the airplane. On the contrary, some FAAmen have been heard to praise what they have seen of it. The crux of the matter is that the FAA has recently ascertained that you -- the actual builder of the plane -- and not Bede, your supplier, contribute more than 51 percent of the effort of construction; the FAA is therefore legally obligated to pass judgment only on what you do with what Bede sends you.
The FAA's general-aviation district offices (GADO) and its engineering and manufacturing district offices (EMDO's) handle homebuilt certifications. They run at least one inspection while the airplane is under construction to see how the builder is doing and to check that the innards of the machine look sound. If something seems wrong, the builder is asked to make corrections, which will in turn be inspected. The final inspection comes upon completion of construction and is similar to the annual inspections of production airplanes. The FAA will check out the structure (as much of it as they can inspect) and the engine run-up; it may ask to see the plane fly, although the time-consuming job of re-closing the aircraft after the structural inspection may leave no time for the busy inspector to wait around for that step. If you've built the airplane right, the man will award you an Experimental ticket. Your machine will still not be eligible for any other designation, not even Normal or Utility, and you will have to renew the Experimental certificate by means of an FAA inspection every year.
It is quite possible that a new rule will be made separating homebuilts into a new Sport or Custom airworthiness category, which could mean requiring initial certification by an FAA inspector and subsequent inspections periodically by an FAA-authorized inspector. But that would not be likely to change the operating limitations that BD-5's will have as experimental-category airplanes.
According to Part 91.42 of the Federal Aviation Regulations, if you are going to build and fly a BD-5, you will be restricted to VFR daytime flying. For night and IFR operations, you must convince the FAA that you have installed the proper equipment and are qualified to fly the plane under such conditions. You cannot use your aircraft for hire. What may cramp your style the most, at least for a while, is the fact that homebuilts are normally restricted to an area within 20 miles of airports approved for their operation and to airspace not covering congested areas until they have flown 50 hours with a type-certificated engine and 75 hours with a non-TC'ed one. The BD-5 engine is not TC'ed yet, though Bede Aircraft is seeking to obtain a TC for it. After the initial 75 hours are flown, you may ask the FAA to remove the 20-mile restriction. If and when they do, you can fly the BD-5 anywhere in the United States except over congested areas. The congested-area limitation may also be lifted in the near future, but only to cover takeoffs and landings on a specified-airport-and-runway basis.
As a homebuilt, your BD-5 generally can be restricted in its operation more than can be a store-bought airplane. For example, the FAA may limit it to operation on large, paved airports. If you want to fly it off a grass field, it may take some convincing to get the FAA to allow it. Furthermore, the FAA would have to approve any aerobatic activity you may want to try in your Bede.
It is still uncertain, moreover, how the FAA will handle the question of who among the many pilots wanting to fly the BD-5 will be considered qualified to do so. If you think you can take dual instruction in it, you'd better look at the plans and photos of it again.
Homebuilding is for patient people, especially when they're most anxious to zoom away in the new offspring they've brought up by hand. Certificating an airplane takes up to two man-days of FAA time, what with transportation time, inspection time and paperwork time. (The annual recertification takes less.) There are only so many FAAmen to go around, and considering the many other tasks they have to go around doing, homebuilt certification is understandably not the hottest number on their list of priorities. As more and more BD-5's near completion or are finished, the waiting line for inspections and certification may stretch longer and longer. One improvement in the procedure you can be thankful for is the fact that when an experimental aircraft is sold, its certification stays valid; it used to terminate with each change of ownership. Nevertheless, the FAA recommends that each owner have an authorized inspector give the machine a thorough going-over.
Again, the responsibility for your BD-5 lies with you, and when Big Brother comes around to look at it, he will be watching with a beady-eyed stare. -- Norbert Slepyan
Last Update: 6/8/97
Web Author: Juan Jiménez
Copyright © 1997 by Juan Jiménez - ALL RIGHTS RESERVED