Bede BD-5

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The BD-5 Micro is a series of small, single-seat [Vous devez être inscrit et connecté pour voir ce lien] aircraft created in the late 1960s by US aircraft designer [Vous devez être inscrit et connecté pour voir ce lien] and introduced to the market primarily in "kit" form by the now-defunct [Vous devez être inscrit et connecté pour voir ce lien] in the early 1970s.

The BD-5 has a small, streamlined 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, mounted immediately to the rear of the cockpit.

The combination of fighter-like looks and relatively low cost led to the BD-5 selling over 5,000 kits or plans, with approximately 12,000 orders being taken for a proposed factory-built [Vous devez être inscrit et connecté pour voir ce lien] certified version.
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However, few of the kit versions were actually completed due to the company's bankruptcy in the mid-1970s, and none of the factory built "D" models produced, brought on by the failure to deliver a reliable engine for the design.

In total, only a few hundred BD-5 kits were completed, although many of these are still being flown today.

The BD-5J version holds the record for the world's lightest jet aircraft, weighing only 358.8 lb (162.7 kg).

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Bede BD-5J at Airpower 11

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Design and development


The Micro concept


Development of the "Micro" dates back as early as 1967, when Jim Bede was inspired by the [Vous devez être inscrit et connecté pour voir ce lien]. At the time, however, Bede was working on the [Vous devez être inscrit et connecté pour voir ce lien] design.

The BD-4 was a fairly conventional looking high-wing four-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.

Serious work on the Micro started in 1970, with construction of the prototype starting in earnest late that year.^{[Vous devez être inscrit et connecté pour voir ce lien]}

While the BD-4 was fairly conventional looking, the Micro was a radical design.

It is an extremely small one-seat design that looked more like a jet fighter than a "prop plane," with the pilot sitting in a
semi-reclined position under a large fighter-like [Vous devez être inscrit et connecté pour voir ce lien] only inches above the pilot's head. Behind the cockpit was a compartment housing a two-cylinder air-cooled 40 hp [Vous devez être inscrit et connecté pour voir ce lien] driving a pusher [Vous devez être inscrit et connecté pour voir ce lien].

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 [Vous devez être inscrit et connecté pour voir ce lien] use. Builders could optionally buy both wings, switching them in about 10 minutes.

For improved performance the aircraft featured both a [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien] in order to reduce [Vous devez être inscrit et connecté pour voir ce lien].

Calculated drag was so low that [Vous devez être inscrit et connecté pour voir ce lien] were added to the wing in order to improve deceleration for landing.

This was apparently the first application of spoilers on a light aircraft.

The low drag implied excellent performance; with the short wings it would reach 210 mph (340 km/h) in cruise, while the long-wing BD-5B would be only slightly slower and have an extended range of 1,215 miles.

In addition to being easy to fly, the BD-5 was also intended to be easy to build and own.

The [Vous devez être inscrit et connecté pour voir ce lien] was constructed primarily from [Vous devez être inscrit et connecté pour voir ce lien] panels over an [Vous devez être inscrit et connecté pour voir ce lien] frame, reducing construction time to only a few hundred hours.

Although the early designs required some [Vous devez être inscrit et connecté pour voir ce lien] in the landing gear area, it was planned that this would be removed in
the kit versions, so construction would require no special tooling or skills. ^{[Vous devez être inscrit et connecté pour voir ce lien]}

Even the cost of operation would be extremely low, offering [Vous devez être inscrit et connecté pour voir ce lien] of almost 40 mpg. With the wings removed the aircraft could be packed into a small custom trailer, allowing it to be towed away by car for storage in a garage, and from there to any suitable flat area for takeoff.

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 August 1973 issue of [Vous devez être inscrit et connecté pour voir ce lien] also covered the aircraft, although it 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 February 24, 1971, the first $200 deposit to reserve a "place in line" to receive a kit was accepted, with the target shipping date being May 24, 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 general aircraft projects in modern history.

Flight testing


The prototype, N500BD, flew briefly on September 12, 1971, powered by a 36 hp [Vous devez être inscrit et connecté pour voir ce lien] engine.

The [Vous devez être inscrit et connecté pour voir ce lien] 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 with the components incorporating compound curves produced using [Vous devez être inscrit et connecté pour voir ce lien] aircraft-grade aluminum alloy.

These could be modified with relative ease during the testing cycle. It 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 the long run.

By December 1971 the tooling for the new fuselage was in development.

The aircraft now featured a longer, more pointed nose, whereas the more ovoid N500BD had been patterned on the ASW 15. While this work was in progress, Bede continued to experiment with modifications to the [Vous devez être inscrit et connecté pour voir ce lien], eventually abandoning the V-tail and changing to a more conventional vertical rudder and horizontal elevator layout with highly swept surfaces.

Further testing on N500BD showed flow interference between the horizontal surfaces and the propeller, and the elevator was raised six inches to correct it, placing it about mid-way up the rear fuselage.

The first example of the new fuselage arrived in March 1972, and was fitted with a new [Vous devez être inscrit et connecté pour voir ce lien] Aeromarine engine Bede had seen at the [Vous devez être inscrit et connecté pour voir ce lien] in 1971.

Finished as N501BD, numerous small delays prevented it from flying until July 11, 1972.

These flights demonstrated continued problems with the pitch stability, so the tail was again redesigned with more area and less sweep, becoming much more conventional.

The program was now far too large for Bede to handle alone. In March 1972, he hired [Vous devez être inscrit et connecté pour voir ce lien] to head the flight test department, who was soon followed by [Vous devez être inscrit et connecté pour voir ce lien] as chief test pilot.^{[Vous devez être inscrit et connecté pour voir ce lien]}

They took over development, giving Bede more time to work on business issues.

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 [Vous devez être inscrit et connecté pour voir ce lien] design, but then selecting a larger 650 cc 55 hp Hirth engine instead.

Several additional problems turned up during testing. [Vous devez être inscrit et connecté pour voir ce lien] forces were very low, but this was easily addressed by making the [Vous devez être inscrit et connecté pour voir ce lien] larger.

A more worrying development was that the engines all had problems with [Vous devez être inscrit et connecté pour voir ce lien] due to changes in engine speed or load, which led to rough engine operation.

In August Bede was demonstrating the BD-5 to the [Vous devez être inscrit et connecté pour voir ce lien] in order to receive permission to fly at Oshkosh, when the engine seized. On its [Vous devez être inscrit et connecté pour voir ce lien], the aircraft overran the runway, buckling the nose gear.

The air-fuel mixture was identified as the cause of the crash of N501BD in September 1972 when the mixture control broke and Berven had to execute a [Vous devez être inscrit et connecté pour voir ce lien].

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 [Vous devez être inscrit et connecté pour voir ce lien] belt drive system to transfer power from the engine to the propeller shaft, but this was removed from N502BD and it suddenly began exhibiting a serious vibration problem.

Experts were called in, a freewheel clutch and additional [Vous devez être inscrit et connecté pour voir ce lien] corrected the problem, but it was not until March 26, 1973 that N502BD flew.

From then on the test program seemed to go more smoothly.

By the time the test program neared its conclusion the aircraft had undergone 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 (the highest available speed).

Flight testing also showed the [Vous devez être inscrit et connecté pour voir ce lien] with the smaller wing was decidedly fast.

Split [Vous devez être inscrit et connecté pour voir ce lien] and spoilers had also disappeared.

The canopy and [Vous devez être inscrit et connecté pour voir ce lien] dimensions had changed, the aircraft had new landing gear systems and a completely new tail section. More ominous was the fact that the engines had already been changed 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 a jet-powered BD-5, the BD-5J, which is detailed below.

Another was the [Vous devez être inscrit et connecté pour voir ce lien], 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" [Vous devez être inscrit et connecté pour voir ce lien], 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 [Vous devez être inscrit et connecté pour voir ce lien] (S for Sailplane) version with lengthened wings and no engine, which prompted Air Progress magazine to sarcastically note, "At last, a BD-5 with no engine problems".

This glider version did not fly well and the project was scrapped. Bede also decided to seek FAA certification of the BD-5D as a production aircraft and sell it complete, and began 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 towork" and hopefully complete the airframe by the time the engine arrived, at that point expected in September 1973. Many builders took the company up on the offer, only to receive incomplete kits and plans.

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.

The latter, which Bede had developed with Hirth, was now considered the baseline engine for the aircraft as the original 40 hp proved to be of insufficient power.

In a late 1973 newsletter to prospective owners, Bede suggested the 70 hp model and discouraged use of the smaller
engines.^{[Vous devez être inscrit et connecté pour voir ce lien]}

Prices had risen throughout the 30 months since the deposits were first taken.

Originally priced at $1,799, the base price was raised to $2,599 with the 55 hp, and owners were offered a "trade up" for the difference in price if they had ordered the aircraft with the original 40 hp engine.

When 1974 came around, the engines were still not being delivered in quantity, 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.

In the meantime, Bede came up with another novel solution to the problems of converting pilots to the new aircraft.

They took an engine-less example and bolted it to the front of a pickup truck on a trapeze, attaching the pilot's throttle control to the truck's.

Pilots could test fly the aircraft without danger - if a problem developed the driver of the truck simply hit the brakes.