Bede BD-5

Template:Infobox Aircraft The BD-5 Micro is a small, single-seat homebuilt kit aircraft introduced in the early 1970s by Jim Bede. It is a very attractive design with a small fuselage holding its semi-reclined pilot under a large canopy, with the engine installed in a compartment in the middle of the fuselage, and a propeller (or jet engine in the BD-5J variant) in the rear. The combination of fighter-like looks and relatively low cost led to the BD-5 becoming a huge sales success, with over 5,000 kits being shipped. However few were actually completed due to the company's bankruptcy in the mid-1970s, brought on by the failure to deliver a reliable engine for the design. In total only a few hundred were completed, although many are still being flown today.

Design and development

Prior to starting work on the BD-5, Jim Bede had introduced the successful Bede BD-4 design. This was a fairly conventional looking high-wing two-seater, but it offered good performance and was fairly inexpensive. Over the lifetime of the company about 600 BD-4s were sold, a success by any measure that allowed Bede to move on to more ambitious designs. Although Bede had apparently first looked at a new design as early as 1967, work on the BD-4 meant he was not able put any serious effort into the new Micro until about 1970. Work on a prototype started in earnest late that year.

While the BD-4 was fairly conventional looking, the Micro was a radical design. It is an extremely small one-seat design that looks more like the jet fighter than prop plane, with the pilot sitting in a semi-reclined position under a large fighter-like plexiglas canopy. Behind the pilot was a compartment housing a two-cylinder air-cooled 40 hp engine driving a pusher propeller. For improved performance the aircraft featured a V-tail and retractable landing gear in order to reduce drag. Drag was so low that in order to improve deceleration for landing spoilers were added to the wing, apparently the first application of spoilers to a light aircraft.

Two versions were planned, the BD-5A with "short" 14' 3" (4.34 m) wings tuned for high speeds and acrobatics, and the BD-5B with a 21' 6" (6.55 m) wings for longer range and powered glider use. Performance of the BD-5A was predicted to be 210 mph (340 km/h) in cruise, while the BD-5B would be only slightly slower and have a range of 1,215 miles. Builders could optionally buy both wings, switching them in about ten minutes. The fuselage was constructed primarily from fiberglass panels over an aluminum frame, reducing construction time to only a few hundred hours.

Bede published an information booklet about the BD-5 in November 1970. Several very positive magazine articles appeared at this point. The October 1971 issue of Science & Mechanics had the BD-5 on the cover, listing the price as $1,950 and a top speed of 215 MPH. The associated article showed the construction of the original prototype, with numerous claims about how easy it was to construct. The same month's issue of Popular Science also covered the aircraft, although they listed the price at $2,965. A feeding frenzy followed as the "mini fighter" generated intense demand. As one author put it, "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."

On 24 February 1971 the first $200 deposit to reserve a "place in line" to receive a kit was accepted, with the target shipping date being 24 May 1972. By August 1971, 800 deposits had been taken, even though the first BD-5 prototype had yet to complete high-speed taxi tests. By the end of the year, they had over 4,300 orders, making it one of the most popular aircraft in modern history.

Flight testing

The prototype, N500BD, flew briefly on 12 September 1971, powered by a 36 hp Polaris Industries snowmobile engine. The stability of the aircraft with the original V-tail was marginal at best, and clearly needed a redesign. With the original fiberglass fuselage this was a time consuming process, so the decision was made to switch to an all-metal fuselage of hydroformed aluminum components. These could be modified with relative ease during the testing cycle. This also made economic sense as the orders rolled in, as assembly-line production of stamped metal parts is expensive to set up but less expensive in production.

By December 1971 the tooling for the new fuselage was in development, also featuring a longer and more "pointy" nose, whereas the N500BD was somewhat "egg shaped", patterned on the Schleicher ASW 15. While this was starting up he continued to experiment with modifications to the tail, eventually abandoning the V-tail and changing to a more conventional three-part layout, but with highly swept surfaces. Further testing on N500BD showed a flow interaction between the horizontal surfaces and the propeller, so the surfaces were moved up six inches to eliminate this, further improving the looks of the aircraft.

The first example of the new fuselage arrived in March 1972, and was fitted with a new Kiekhaefer Aeromarine engine Bede had seen at the Oshkosh Airshow in 1971. Finished as N501BD, numerous little delays prevented it from flying until 11 July 1972. These flights demonstrated continued problems with the tail design, which was again redesigned, losing the sweep and becoming fairly conventional looking.

The program was now far too large for Bede to handle alone, and in March, 1972 he hired Burt Rutan to head the flight test department, and was soon joined by Les Berven, as test pilot. They took over development, giving Bede more time to work on the business. This was proving difficult enough, as Kiekhaefer and Bede could not reach an agreement about deliveries, forcing him to change to a similar 440 cc 40 hp Hirth Motoren design, but then selecting a larger 650 cc 55 hp Hirth engine instead.

Several additional problems turned up during testing. One was that the stick forces were very low, but this was easily addressed by making the servo tabs larger. A more worrying development was that the engines all had problems with mixture due to changes in RPM or load, which lead to rough running. In August Bede was demonstrating the plane to the FAA in order to receive permission to fly at Oshkosh, when the engine seized. On its dead-stick landing, the airplane overran the runway, buckling the nosegear. Mixture was definitely the cause of the crash of N501BD in September 1972 when the mixture control broke and Breven had to execute a forced landing. Since N502BD would be ready in two months, N501BD was not repaired.

However, N502BD ran into problems of its own. The earlier models used a variable speed belt system between the engine and the prop, but this was removed from N502BD and it suddenly started exhibiting a serious vibration problem. Experts were called in and additional bearings fixed the problem, but it was not until 26 March 1973 that N502BD flew. From then on the test program seemed to go more smoothly.

By the time the test program was starting to reach its conclusions the plane had undergone some fairly major changes. One victim of the program was the shorter "A" wing, which calculations showed would only improve performance at speeds very close to V_max, at slower speeds there was little or no advantage. Additionally it was found that the landing speed with the smaller wing was decidedly fast. Split flaps and spoilers also disappeared. The canopy and cockpit dimensions had changed, there was a complete new tail section, new landing gear systems, and more ominously, they had already changed the engine twice. What remained, however, was the basic concept of the fighter-like pusher aircraft, which, if anything, had improved in looks.

By this point it seemed the basic design was complete, and Bede turned his attention to other projects. One was jet-powered BD-5, the BD-5J, which is detailed below. Another was Bede BD-6, a single-seat version of the BD-4 based on the same Hirth engine being used in the BD-5. Still another was the "new" Bede BD-7, a two-seat side-by-side version of the BD-5 of which a prototype was built. There was even an attempt to sidestep the engine problem with the BD-5S, a glider (S for Sailplane) version with lengthened wings and no engine, which prompted Air Progress magazine sarcastically note, "At last, a BD-5 with no engine problems". This glider version did not fly very well and the project was scrapped. Additionally, Bede decided to seek FAA certification of the BD-5D as a production aircraft and sell it complete, taking $600 deposits for this model.

Deliveries begin

By the middle of 1973 the basic design was complete and the tooling set up for production. The engines were the only part holding up deliveries, so Bede offered to ship the kit with the engine to follow. This was a fairly attractive option; it meant the builder could "get to work" and hopefully complete the airframe by the time the engine arrived, at that point expected in September 1973.

All three Hirth engines were offered, builders could keep the 40 hp design, or "trade up" to the larger 55 hp or 70 hp engines then being offered. The later, which Bede had developed with Hirth, was now considered the baseline engine for the aircraft as the original 40 hp model proved to be too small. In a late 1973 newsletter to prospective owners, Bede suggested the 70 hp model and discouraged use of the smaller engines. Prices had risen throughout the two and a half years since the deposits were first taken. Originally priced at $1,799, the base price was now $2,599 with the 55 hp, and owners were offered a "trade up" for the difference in price if they had ordered with the original 40 hp engine.

When 1974 came around, the engines were still not being delivered, although some started to arrive early that year. At that point, unexpectedly, Hirth went bankrupt after about 500 of the engines had shipped. Once again the design lacked a suitable engine, but this time the search for a replacement ended with a Xenoah design from Japan. Development of this engine was lengthy, and in the end it would not be certified for export until 1978, although this was not expected at the time.

Deliveries end

After more than 5,100 kits had been delivered to prospective builders, the kits stopped shipping as well. Although the company was effectively bankrupt at this point, work on the BD-5D continued for some time. The bankruptcy became official in 1979, by which point the BD-5 project was long dead. During the bankruptcy proceedings it was learned that the money ostensibly being used to build kits was instead being spent on a variety of projects. As a result, Bede entered a consent decree with the FTC to no longer accept deposits on aircraft for a period of ten years.

BD-5B built, owned and flown by retired USAF pilot Dan Ross. The scoop under the fuselage identifies this as being Rotax powered.

Many owners abandoned their kits, some of which were incomplete, but a few hundred diehard builders finished them with a variety of third party engine installation designs. Having to hunt for an engine was only one problem, another being that the time to built the aircraft was much longer than quoted, requiring thousands of hours in most cases. Some of this was due to the need to fit their selected engine into an airframe designed for the Hirth, which was no longer available. Additionally, some of the kits were shipped with missing parts, adding to the confusion. All of this led to a rash of kits being sold for fire-sale prices, although this did allow the builders that were looking to complete kits do so without spending too much more. And while Bede claimed the aircraft could be put together by anyone in a garage, builders generally agree that doing so will result in a potentially dangerous aircraft, and construction should only proceed on a set of properly laid-out jigs. For all of these reasons, it was some time before completed BD-5s started to appear.

Over the next few years the aircraft garnered what at first glance appears to be a terrible safety record. The earliest kits shipped with the short "A" wings (optionally), and all four examples completed with these wings crashed on their first flight, with three fatalities, largely a side effect of a 100 mph (160 km/h) landing speed combined with the tiny wheelbase. Nevertheless the current record holder of the FAI C-1a/0 (300 kg or less takeoff weight) class speed record over a 3k m course at restricted altitude is a BD-5A (listed as BD-5B but used -5A wings for the record attempt) with a Rotax 618UL 74 hp two-stroke, three-cylinder water-cooled engine. Rotax-equipped BD-5s are generally easy to distinguish due to the small radiator "scoop" under the fuselage.

Crashes in the B models were generally due to an engine failure on takeoff, both due to the mix of "oddball" engines as well as endemic cooling problems. The reason this is such an issue with the BD-5 is twofold – the high line of thrust means an engine failure immediately results in a nose-up attitude, and the pilots who failed to fly the aircraft first and then attempt to restart the engine inevitably stalled, with the associated consequences. This was not the only problem; the original wing had a very sharp stall with little warning. A rather small center of gravity range also added to the problems of properly trimming the aircraft.

Further developments

With the demise of Bede the BD-5 entered a sort of limbo while builders completed their kits. The early safety problems and the problems of adapting a suitable engine added to the problems. But over the next few years, solutions to most of these problems arrived in one form or another. Many other changes have also been incorporated to improve the original design. Today the BD-5 is a rewarding, if demanding aircraft.

For instance, the problem of finding a suitable engine with 60 to 70 hp yet still weighing under 100 lbs was a serious problem in the 1970s, but today there are a number of "off the shelf" designs in this class. For instance, the widely available Rotax 582 is a 65 hp engine of 80 lbs in standard configuration, almost tailor-made for the BD-5. Better yet, the Rotax is liquid-cooled, thereby greatly simplifying the cooling problems earlier air-cooled engines had.

Problems with the abrupt stall were addressed by Harry Riblett, who produced a slight reprofile of the wing root airfoil that softened the stall response of the aircraft. But it presented other unique problems associated with the way the reprofile was to be performed, essentially gluing foam to the aluminum skin and covering with fiberglass. Similarly, the small CoG range has since been addressed via small stretches to the fuselage.

Several companies were formed to help builders complete their kits, and many of the aftermarket modifications were worked into these services. Today, BD Micro Technologies of Siletz, Oregon continues to offer kitbuilding support, including new-build kits featuring (optionally) all of these modifications, and even the BD-5T, a turboprop version of the BD-5 using a modified Solar/Hamilton Sundstrand T62 turbine powering a mechanically-controlled variable-pitch propeller.

An unusual adaptation of the BD-5, the Acapella 100, appeared in the early 1980s. Designer Carl D. Barlow of Option Air Reno mated a BD-5 fuselage with a distinctive twin-boom empennage and fitted it with a 100 hp Continental O-200 engine. Later, a 200 hp Lycoming IO-360 was fitted, and the wings shortened from 26.5 feet to 19.5 feet, becoming the Acapella 200-S model. The prototype of this aircraft was first flown on 6 June 1980, with pilot Bill Skiliar at the controls. Unfortunately, it did not fly well and was difficult to control. Only the one prototype was built and it was donated to the Experimental Aircraft Association's Airventure Museum in Oshkosh, Wisconsin, USA, where it is occasionally placed on display.

Bede has since re-formed and has been working on several new designs. He has hinted at a two-seat tandem version of the aircraft called the "Super BD-5" using a certified aircraft engine and a number of modifications and improvements, but to date nothing other than a preliminary design drawing has been made available.

BD-5J

"Bud Light Jet" BD-5J at Fargo 1997

While the new Hirth engine was being tested, Bede decided to create an unconventional variant of the BD-5 with a small jet engine. The result was the BD-5J, a 300 mph (480 km/h) aircraft that looked fast while sitting on the ramp. The design used the Sermel TRS-18-046 turbojet (now Microturbo, a division of Turbomeca), which produced 225 lbf thrust. The original engines were produced under license by Ames Industrial in the US. The wing was modified to an "intermediate" size between the original A and B wings, with a 17 ft span.

Bob Bishop had purchased 20 BD-5J kits as soon as they had appeared, and many of the flying examples started life in this batch of twenty. Versions from the original batch became a popular airshow fixture. Throughout the 1980s until 1991, Coors flew two of them as the "Silver Bullets." Budweiser also had a BD-5J called the "Bud Light Jet", but that contract has long expired. The aircraft also appeared in the opening sequence of the James Bond film, Octopussy.

A large number of these aircraft have since been involved in crashes. The Bud Light Jet crashed after a fuel flow sensor burst in mid-flight, causing a fire in the engine compartment, although the pilot was able to escape safely. While practicing for an air show, Scott Manning fatally crashed in the "Stinger Jet," the last BD-5J that remained on the air show circuit, on 16 June 2006 at Carp Airport, Canada.

The BD-5J was recently certified as a cruise missile surrogate, with Bishop's Aerial Productions offering a version known as the Smart-1 (Smart Manned Aerial Radar Target, Model 1). The radar return and general performance characteristics made it a useful aid in training. On 27 June 2006, while flying one of these aircraft, pilot Chuck Lischerone, a highly experienced professional air show pilot, impacted trees on his final approach to the Ocean City Municipal Airport in Ocean City, Maryland in a fatal accident.

The BD-5J has also held the Guinness record for the World's Smallest Jet for more than 25 years. Bob Bishop originally garnered the record with one of his jets, and in November 2004 the record changed hands to Juan Jiménez, whose BD-5J weighed in at 358.8 lbs (162.8 kg) empty weight, 80 lbs (36 kg) lighter than Bishop's jet. The primary difference is the use of an earlier Microturbo turbojet, the 022 Couguar, which weighs only 68 lbs (31 kg).

Surviving Aircraft

As of 2002, there were an estimated 150 BD-5s in airworthy condition.

A BD-5 is on display at the Steven F. Udvar-Hazy Center, an annex of the National Air and Space Museum at Washington Dulles International Airport in Chantilly, Virginia.

The BD-5J from Octopussy is on display in the Pima Air and Space Museum in Arizona.Pima Air and Space Museum

Specifications (BD-5B)

Ron and Phyllis Loewen's Bede BD-5B C-FGXC, Manitoba Air Show 2007

Data from {name of first source}

General characteristics

• Crew: one, pilot

Performance

References

• Aleith, Richard. "Bede BD-5." Air Progress Sport Aircraft 1973. Los Angeles: Petersen Publishing Company, 1973. ISBN 0-8227-0047-6.
• "The Amzing BD-5: Sonofagun... It Flies!" Air Progress Vol. 31, no. 4, October 1972.
• "BD-5J: The World's Smallest Jet." Airshow International Vol. 1, no. 2, Summer 1993.
• Davisson, Budd. "Okay, BD-5 Customers, Start Smiling!" Air Progress Vol. 37, no. 3, November 1974.
• Noland, Dave. "The Agony and the Ecstasy of the BD-5 Builder." Air Progress (Part 1) Vol. 33, no. 4, October 1973, (Part 2) Vol. 34, no. 4, April 1974.
• Weeghman, Richard B. "Microcosm." Air Progress Vol. 34, no. 2, February 1974.
• Winchester, Jim. "Bede BD-10." Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft. Kent, UK: Grange Books plc., 2005. ISBN 1-84013-309-2.

External links

• Official Web Site of the BD-5 Network
• National Air and Space Museum page on the BD-5
• BD Micro Technologies
• Alturair, Inc.
• Jon Ruthven's BD-5 Project
• Safran Group - Microturbo - Manufacturers of the TRS-18 turbojet engine used on most BD-5J Microjets