Misplaced Pages

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99-537: Developed concurrently with the Yak-30, the Yak-32 was a single-seat aircraft designed as both a sporting jet, and a light military ground attack aircraft. The airframe of the Yak-32 was that of the Yak-30, but modified to include only a single seat. Yakovlev had intended to market the aircraft as a sporting jet at a time when no other single-seat jet aircraft were being marketed for civilian use. In fact, it would not be until

198-621: A 300 mph (260 kn; 480 km/h) aircraft. The design used the PBS Velká Bíteš PBS TJ100 turbojet with 337 lb (1.5 kN) thrust and the Sermel TRS-18 -046 turbojet which produced 225  lbf (1.00  kN ) thrust and which was used on a Caproni certified motorglider design. The original Sermel engines were produced under license by Ames Industrial in the USA. The wing was modified to an "intermediate" size between

297-403: A Rotax 618 UL 74  hp (55  kW ; 75  PS ) two-stroke two-cylinder, water-cooled engine holds the current FAI C-1a/0 class speed record (aircraft weighing under 660 lb (300 kg)) at 351 km/h (190 kn; 218 mph). Problems with the abrupt stall were mostly addressed by Harry Riblett , an airfoil designer who documented a procedure to apply a slight reprofile of

396-476: A limit value of one, for large time t . In other words, velocity asymptotically approaches a maximum value called the terminal velocity v t : v t = 2 m g ρ A C D . {\displaystyle v_{t}={\sqrt {\frac {2mg}{\rho AC_{D}}}}.\,} For an object falling and released at relative-velocity v  = v i at time t  = 0, with v i < v t ,

495-665: A limit value of one, for large time t . Velocity asymptotically tends to the terminal velocity v t , strictly from above v t . For v i = v t , the velocity is constant: v ( t ) = v t . {\displaystyle v(t)=v_{t}.} These functions are defined by the solution of the following differential equation : g − ρ A C D 2 m v 2 = d v d t . {\displaystyle g-{\frac {\rho AC_{D}}{2m}}v^{2}={\frac {dv}{dt}}.\,} Or, more generically (where F ( v ) are

594-499: A variable speed belt drive system to transfer power from the engine to the propeller shaft. This was removed from N502BD and it suddenly began exhibiting a serious vibration problem during taxi tests. Experts were called in, and a freewheel clutch and additional bearings added to correct the problem, but it was not until March 26, 1973, that N502BD flew. From then on the test program seemed to go more smoothly, although this aircraft also suffered two dead stick landings, one from

693-515: A BD-5 with no engine problems." This glider version did not fly well and the project was scrapped. Some work on a BD-6 was also carried out, essentially a downsized BD-4 single-seater. There was some criticism that Bede should have attended to the basic BD-5 rather than move on to these other projects. 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. By

792-511: A ZB-500 or ZB-360 external fuel tank, bombs of up to 500 kg, up to four rocket launchers (the largest being the UB-32/S-5), up to four K-13/R-3S missiles, four ARS-240 rockets, or four AOI-9 or UKP-23 gun pods, each with 250 rounds. On 5 August 1971, one of the Yak-32s was ordered to be equipped with RU19P-300 which has been modified to permit longer inverted flight. The aircraft received

891-403: A few hundred hours. Although the early designs required some welding 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. Even the cost of operation would be extremely low, offering fuel efficiency of 38 mpg ‑US (16 km/L). With the wings removed, the aircraft could be packed into

990-809: A fluid at relatively slow speeds (assuming there is no turbulence). Purely laminar flow only exists up to Re = 0.1 under this definition. In this case, the force of drag is approximately proportional to velocity. The equation for viscous resistance is: F D = − b v {\displaystyle \mathbf {F} _{D}=-b\mathbf {v} \,} where: When an object falls from rest, its velocity will be v ( t ) = ( ρ − ρ 0 ) V g b ( 1 − e − b t / m ) {\displaystyle v(t)={\frac {(\rho -\rho _{0})\,V\,g}{b}}\left(1-e^{-b\,t/m}\right)} where: The velocity asymptotically approaches

1089-450: A fluid increases as the cube of the velocity increases. For example, a car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome aerodynamic drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speeds, the drag/force quadruples per the formula. Exerting 4 times the force over a fixed distance produces 4 times as much work . At twice

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1188-556: A highly experienced professional air show pilot, was killed when he crashed into trees on final approach to the Ocean City Municipal Airport in Ocean City , Maryland . The National Transportation Safety Board investigation determined the aircraft returned to land with more fuel than recommended for normal operations and the pilot failed to maintain speed, resulting in a stall and subsequent impact short of

1287-693: A human body ( d {\displaystyle d} ≈0.6 m) v t {\displaystyle v_{t}} ≈70 m/s, for a small animal like a cat ( d {\displaystyle d} ≈0.2 m) v t {\displaystyle v_{t}} ≈40 m/s, for a small bird ( d {\displaystyle d} ≈0.05 m) v t {\displaystyle v_{t}} ≈20 m/s, for an insect ( d {\displaystyle d} ≈0.01 m) v t {\displaystyle v_{t}} ≈9 m/s, and so on. Terminal velocity for very small objects (pollen, etc.) at low Reynolds numbers

1386-655: 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 30 months since deposits were first taken. Originally priced at $ 1,799, the base price was raised to $ 2,599 with the 55 hp Hirth, 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, engines were still not being delivered in sufficient numbers, although some started to arrive early that year. At that point, unexpectedly, Hirth went bankrupt after about 500 engines had shipped. Once again,

1485-674: A minimum at some airspeed - an aircraft flying at this speed will be at or close to its optimal efficiency. Pilots will use this speed to maximize endurance (minimum fuel consumption), or maximize gliding range in the event of an engine failure. Drag depends on the properties of the fluid and on the size, shape, and speed of the object. One way to express this is by means of the drag equation : F D = 1 2 ρ v 2 C D A {\displaystyle F_{\mathrm {D} }\,=\,{\tfrac {1}{2}}\,\rho \,v^{2}\,C_{\mathrm {D} }\,A} where The drag coefficient depends on

1584-483: A more conventional rudder and horizontal stabilizer layout with highly swept surfaces. Further testing on N500BD showed flow interference between the horizontal surfaces and the propeller, and the stabilizer was raised six inches to correct it, placing it about midway up the rear fuselage. The first example of the new fuselage arrived in March 1972, and was fitted with a new Kiekhaefer Aeromarine engine Bede had seen at

1683-529: A nasty tendency to snap roll . To make matters worse, a documented manufacturing error in some wing skins delivered to kit builders exacerbated the problem. A rather small center of gravity range added to the problems of properly trimming the aircraft. With the demise of the Bede Aircraft Company, the BD-5 entered a sort of limbo while builders completed their kits. The early safety problems and

1782-482: A period of 10 years. Many owners stored, abandoned, or sold their incomplete kits, but a few hundred diehard builders finished them with a variety of engines, with installations designed by third parties and former Bede Aircraft dealers. Having to hunt for an engine was only one problem. The time to build the aircraft was much longer than quoted; original estimates from the company put it at 600 to 800 hours but users estimated it to be as much as 3,500 hours. Some of this

1881-511: A pinched fuel line occurred while the plane was being observed by the Popular Science author, and another due to metal in a new engine's cylinder. 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

1980-426: A redesign. With the original fibreglass 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 hydroformed 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, the $ 30,000 in tooling would be spread over what

2079-471: 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. The associated article showed

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2178-468: A small sphere with radius r {\displaystyle r} = 0.5 micrometre (diameter = 1.0 μm) moving through water at a velocity v {\displaystyle v} of 10 μm/s. Using 10 Pa·s as the dynamic viscosity of water in SI units, we find a drag force of 0.09 pN. This is about the drag force that a bacterium experiences as it swims through water. The drag coefficient of

2277-514: A solid surface. Drag forces tend to decrease fluid velocity relative to the solid object in the fluid's path. Unlike other resistive forces, drag force depends on velocity. This is because drag force is proportional to the velocity for low-speed flow and the velocity squared for high-speed flow. This distinction between low and high-speed flow is measured by the Reynolds number . Examples of drag include: Types of drag are generally divided into

2376-623: A sphere can be determined for the general case of a laminar flow with Reynolds numbers less than 2 ⋅ 10 5 {\displaystyle 2\cdot 10^{5}} using the following formula: C D = 24 R e + 4 R e + 0.4   ;           R e < 2 ⋅ 10 5 {\displaystyle C_{D}={\frac {24}{Re}}+{\frac {4}{\sqrt {Re}}}+0.4~{\text{;}}~~~~~Re<2\cdot 10^{5}} For Reynolds numbers less than 1, Stokes' law applies and

2475-463: A task, but with the all-metal version this was extremely time-consuming. While Bede claimed the aircraft could be put together by anyone in a garage, builders generally agree that doing so without proper construction techniques could result in a potentially dangerous aircraft. One way to overcome that issue is to use a set of properly laid-out jigs to align and drill the pilot holes for the airframe, wings and other components. For all of these reasons, it

2574-559: A time. It was the need for more power that would fit into the very small engine bay that demanded the use of a high-revving two-stroke engine , and few examples of such a design in the desired power class were available. Additionally, two-stroke engines are very smooth running at high RPM, but have real problems running smoothly at low RPM. Even after months of effort, the Hirth designs showed rough running and high minimum power outputs when idled. Two-strokes also have high fuel consumption, and it

2673-410: 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 nothing more than a preliminary design drawing was made available. While the new Hirth engine was being tested, Bede decided to create a variant of the BD-5 with a small jet engine . The result was the sleek BD-5J (also known as the "Acrostar Jet" ),

2772-558: Is about v t = g d ρ o b j ρ . {\displaystyle v_{t}={\sqrt {gd{\frac {\rho _{obj}}{\rho }}}}.\,} For objects of water-like density (raindrops, hail, live objects—mammals, birds, insects, etc.) falling in air near Earth's surface at sea level, the terminal velocity is roughly equal to with d in metre and v t in m/s. v t = 90 d , {\displaystyle v_{t}=90{\sqrt {d}},\,} For example, for

2871-448: Is also defined in terms of the hyperbolic tangent function: v ( t ) = v t tanh ⁡ ( t g v t + arctanh ⁡ ( v i v t ) ) . {\displaystyle v(t)=v_{t}\tanh \left(t{\frac {g}{v_{t}}}+\operatorname {arctanh} \left({\frac {v_{i}}{v_{t}}}\right)\right).\,} For v i > v t ,

2970-625: Is asymptotically proportional to R e − 1 {\displaystyle \mathrm {Re} ^{-1}} , which means that the drag is linearly proportional to the speed, i.e. the drag force on a small sphere moving through a viscous fluid is given by the Stokes Law : F d = 3 π μ D v {\displaystyle F_{\rm {d}}=3\pi \mu Dv} At high R e {\displaystyle \mathrm {Re} } , C D {\displaystyle C_{\rm {D}}}

3069-399: Is determined by Stokes law. In short, terminal velocity is higher for larger creatures, and thus potentially more deadly. A creature such as a mouse falling at its terminal velocity is much more likely to survive impact with the ground than a human falling at its terminal velocity. The equation for viscous resistance or linear drag is appropriate for objects or particles moving through

Yakovlev Yak-32 - Misplaced Pages Continue

3168-408: Is known as bluff or blunt when the source of drag is dominated by pressure forces, and streamlined if the drag is dominated by viscous forces. For example, road vehicles are bluff bodies. For aircraft, pressure and friction drag are included in the definition of parasitic drag . Parasite drag is often expressed in terms of a hypothetical. This is the area of a flat plate perpendicular to the flow. It

3267-406: Is made up of multiple components including viscous pressure drag ( form drag ), and drag due to surface roughness ( skin friction drag ). Additionally, the presence of multiple bodies in relative proximity may incur so called interference drag , which is sometimes described as a component of parasitic drag. In aviation, induced drag tends to be greater at lower speeds because a high angle of attack

3366-428: Is more or less constant, but drag will vary as the square of the speed varies. The graph to the right shows how C D {\displaystyle C_{\rm {D}}} varies with R e {\displaystyle \mathrm {Re} } for the case of a sphere. Since the power needed to overcome the drag force is the product of the force times speed, the power needed to overcome drag will vary as

3465-472: Is presented at Drag equation § Derivation . The reference area A is often the orthographic projection of the object, or the frontal area, on a plane perpendicular to the direction of motion. For objects with a simple shape, such as a sphere, this is the cross sectional area. Sometimes a body is a composite of different parts, each with a different reference area (drag coefficient corresponding to each of those different areas must be determined). In

3564-473: Is required to maintain lift, creating more drag. However, as speed increases the angle of attack can be reduced and the induced drag decreases. Parasitic drag, however, increases because the fluid is flowing more quickly around protruding objects increasing friction or drag. At even higher speeds ( transonic ), wave drag enters the picture. Each of these forms of drag changes in proportion to the others based on speed. The combined overall drag curve therefore shows

3663-411: Is such an issue with the BD-5 is twofold – the high line of thrust means an engine failure immediately results in an unexpected (for most pilots) nose-up attitude change. Pilots who fail to fly the aircraft first and then attempt to restart the engine inevitably stall , with the associated consequences. This was aggravated by the fact the original wing had a very sharp stall with little warning and

3762-583: Is the Reynolds number related to fluid path length L. As mentioned, the drag equation with a constant drag coefficient gives the force moving through fluid a relatively large velocity, i.e. high Reynolds number , Re > ~1000. This is also called quadratic drag . F D = 1 2 ρ v 2 C D A , {\displaystyle F_{D}\,=\,{\tfrac {1}{2}}\,\rho \,v^{2}\,C_{D}\,A,} The derivation of this equation

3861-755: Is the wind speed and v o {\displaystyle v_{o}} is the object speed (both relative to ground). Velocity as a function of time for an object falling through a non-dense medium, and released at zero relative-velocity v  = 0 at time t  = 0, is roughly given by a function involving a hyperbolic tangent (tanh): v ( t ) = 2 m g ρ A C D tanh ⁡ ( t g ρ C D A 2 m ) . {\displaystyle v(t)={\sqrt {\frac {2mg}{\rho AC_{D}}}}\tanh \left(t{\sqrt {\frac {g\rho C_{D}A}{2m}}}\right).\,} The hyperbolic tangent has

3960-547: Is used when comparing the drag of different aircraft For example, the Douglas DC-3 has an equivalent parasite area of 2.20 m (23.7 sq ft) and the McDonnell Douglas DC-9 , with 30 years of advancement in aircraft design, an area of 1.91 m (20.6 sq ft) although it carried five times as many passengers. Lift-induced drag (also called induced drag ) is drag which occurs as

4059-523: The BD-5T , a turboprop version using a Microturbo TRS 18 turbine powering a mechanically controlled variable-pitch propeller. Alturair, Inc. of San Diego, California also offers extensive parts and construction assistance services, as well as kits for the BD-5B and BD-5G models. Bede Aircraft Company has since re-formed and has been working on several new designs. Before his death in 2015, Bede hinted at

Yakovlev Yak-32 - Misplaced Pages Continue

4158-514: The Oshkosh Airshow 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; after briefly considering an all-flying stabilator, it was again redesigned with more area and less sweep, becoming much more conventional in layout. The program was now far too large for Bede to handle alone. In March 1972, he hired Burt Rutan to head

4257-410: The lift coefficient also increases, and so too does the lift-induced drag. At the onset of stall , lift is abruptly decreased, as is lift-induced drag, but viscous pressure drag, a component of parasite drag, increases due to the formation of turbulent unattached flow in the wake behind the body. Parasitic drag , or profile drag, is drag caused by moving a solid object through a fluid. Parasitic drag

4356-413: The order 10 ). For an object with well-defined fixed separation points, like a circular disk with its plane normal to the flow direction, the drag coefficient is constant for Re  > 3,500. The further the drag coefficient C d is, in general, a function of the orientation of the flow with respect to the object (apart from symmetrical objects like a sphere). Under the assumption that

4455-442: The stall speed with the smaller wing was decidedly high. Split flaps and spoilers had also disappeared. The canopy and cockpit dimensions had changed, the aircraft had new landing gear systems, and the tail was completely new. Estimated top speed was also reduced 10%. The biggest change, however, was the engine. The original plans to use a 40 hp model proved to be decidedly underpowered, although they were still offered for

4554-549: The 1970s, but today there are a number of off-the-shelf designs in this class. The widely available Rotax 582 is a 65 hp (48 kW; 66 PS) engine weighing 80 lb (36 kg) in standard configuration, almost tailor-made for the BD-5. Other engines successfully used in BD-5s include the Subaru EA-81 , Honda EB1 & EB2 (with and without turbocharging), Hirth 2706 , AMW 225-3 and 2SI 808 . A BD-5A fitted with

4653-436: The BD-5 lacked a suitable engine, but this time the search for a replacement ended with a Zenoah 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 anticipated 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

4752-506: The BD-5 selling over 5,000 kits or plans, with approximately 12,000 orders being taken for a proposed factory-built, FAA -certified version. 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 were produced, as a result of the failure to find a reliable engine for the design. In total, only a few hundred BD-5 kits were completed, although many of these are still airworthy today. The BD-5J version holds

4851-687: The BD-5J has operated in the national security arena. The aircraft is certified by the United States Department of Defense as a cruise missile surrogate, with Bishop's Aerial Productions offering a version known as the Smart-1 (Small Manned Aerial Radar Target, Model 1). The radar return and general performance characteristics make it a useful aid in training defense tactics against non-stealth subsonic cruise missiles. On June 27, 2006, while flying one of these aircraft, pilot Chuck Lischer,

4950-526: The FAI as 800 kg). The ASCC allocated the name "Mantis" to the Yak-32/Yak-104. Data from General characteristics Performance Related development Aircraft of comparable role, configuration, and era Bede BD-5 The Bede BD-5 Micro is a series of small, single-seat homebuilt aircraft created in the late 1960s by US aircraft designer Jim Bede and introduced to

5049-454: The World's Aircraft 1974-5, p.250 General characteristics Performance Related lists Drag (physics) In fluid dynamics , drag , sometimes referred to as fluid resistance , is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid . This can exist between two fluid layers, two solid surfaces, or between a fluid and

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5148-413: The airflow and forces the flow to move downward. This results in an equal and opposite force acting upward on the wing which is the lift force. The change of momentum of the airflow downward results in a reduction of the rearward momentum of the flow which is the result of a force acting forward on the airflow and applied by the wing to the air flow; an equal but opposite force acts on the wing rearward which

5247-407: The airplane produces lift, another drag component results. Induced drag , symbolized D i {\displaystyle D_{i}} , is due to a modification of the pressure distribution due to the trailing vortex system that accompanies the lift production. An alternative perspective on lift and drag is gained from considering the change of momentum of the airflow. The wing intercepts

5346-526: The airshow circuit. The Transportation Safety Board of Canada report assigned probable cause of the wreck to the incorrect installation of the right wing, which caused the flap on that wing to suddenly retract in flight and create a "split flap" condition. The aircraft rolled to the right and Manning was unable to recover in time. On May 1, 2013, Guido Gehrmann was killed while attempting an emergency landing in his BD-5J which he flew as part of Red Bull's Flying Bulls team. Beginning in approximately 2004,

5445-453: The case of a wing , the reference areas are the same, and the drag force is in the same ratio as the lift force . Therefore, the reference for a wing is often the lifting area, sometimes referred to as "wing area" rather than the frontal area. For an object with a smooth surface, and non-fixed separation points (like a sphere or circular cylinder), the drag coefficient may vary with Reynolds number Re , up to extremely high values ( Re of

5544-406: The challenge of adapting a suitable engine exacerbated delays. Over the next few years, however, solutions to most of these problems arrived in one form or another. Many other changes have also been incorporated to improve the original design. The problem of finding a suitable engine with 60–70 hp (45–52 kW; 61–71 PS) yet weighing under 100 lb (45 kg) was a serious problem in

5643-432: The company up on the offer, only to receive incomplete kits and plans. Initially, all three Hirth engines were offered; builders could keep the 40 hp engine, or "trade up" to 55 hp or 70  hp (52  kW ; 71  PS ). The latter, which Bede had developed with Hirth, was now considered the baseline engine for the aircraft; when equipped with the original 40 hp the aircraft proved to be underpowered. In

5742-493: 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 other projects. As a result, Bede entered a consent decree with the FTC to no longer accept deposits on aircraft for

5841-443: The construction of the original prototype, with numerous claims about how easy it was to construct. The August 1973 issue of Popular Science also covered the aircraft, although it listed the price at $ 2,965 with the 40 hp engine. The "miniature 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

5940-415: The designation Yak-32P. Flight evaluation of the aircraft was just as good as the original Yak-32. Three Yak-32 prototypes were built in 1960—1961 at the same time as the four prototype Yak-30s trainers. They had callsigns 32, 60 and 70. The aircraft 30 and 70 gave aerobatic demonstrations at the 1961 Aviation Day at Tushino . They went on to set several world class records (their thrust being misreported to

6039-678: The drag coefficient C D {\displaystyle C_{\rm {D}}} as a function of Bejan number and the ratio between wet area A w {\displaystyle A_{\rm {w}}} and front area A f {\displaystyle A_{\rm {f}}} : C D = 2 A w A f B e R e L 2 {\displaystyle C_{\rm {D}}=2{\frac {A_{\rm {w}}}{A_{\rm {f}}}}{\frac {\mathrm {Be} }{\mathrm {Re} _{L}^{2}}}} where R e L {\displaystyle \mathrm {Re} _{L}}

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6138-487: The drag coefficient approaches 24 R e {\displaystyle {\frac {24}{Re}}} ! In aerodynamics , aerodynamic drag , also known as air resistance , is the fluid drag force that acts on any moving solid body in the direction of the air's freestream flow. Alternatively, calculated from the flow field perspective (far-field approach), the drag force results from three natural phenomena: shock waves , vortex sheet, and viscosity . When

6237-620: The drag constant: b = 6 π η r {\displaystyle b=6\pi \eta r\,} where r {\displaystyle r} is the Stokes radius of the particle, and η {\displaystyle \eta } is the fluid viscosity. The resulting expression for the drag is known as Stokes' drag : F D = − 6 π η r v . {\displaystyle \mathbf {F} _{D}=-6\pi \eta r\,\mathbf {v} .} For example, consider

6336-551: The flight test department, who was soon joined by Les Berven as chief test pilot. 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 40 hp 440 cc (27 cu in) Hirth Motoren design, then selecting a larger 55 hp 650 cc (40 cu in) Hirth, instead. Several additional problems turned up during testing. Stick forces were very low, but this

6435-441: The fluid is not moving relative to the currently used reference system, the power required to overcome the aerodynamic drag is given by: P D = F D ⋅ v = 1 2 ρ v 3 A C D {\displaystyle P_{D}=\mathbf {F} _{D}\cdot \mathbf {v} ={\tfrac {1}{2}}\rho v^{3}AC_{D}} The power needed to push an object through

6534-502: The flying examples started life in this batch of 20. Versions from the original batch became a popular airshow fixture. Throughout the 1980s and 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 and the aircraft was lost as a result of an engine compartment fire from which Bishop successfully bailed out. The aircraft also appeared in

6633-411: The following categories: The effect of streamlining on the relative proportions of skin friction and form drag is shown for two different body sections: An airfoil, which is a streamlined body, and a cylinder, which is a bluff body. Also shown is a flat plate illustrating the effect that orientation has on the relative proportions of skin friction, and pressure difference between front and back. A body

6732-448: The forces acting on the object beyond drag): 1 m ∑ F ( v ) − ρ A C D 2 m v 2 = d v d t . {\displaystyle {\frac {1}{m}}\sum F(v)-{\frac {\rho AC_{D}}{2m}}v^{2}={\frac {dv}{dt}}.\,} For a potato-shaped object of average diameter d and of density ρ obj , terminal velocity

6831-429: The four crashes, the pilots were killed. Of the first 25 aircraft completed, with both the "A" and "B" wings, 14 crashed with 9 fatalities. Even when examples with the "B" wings were completed, the safety record did not improve greatly. Several crashes in the BD-5B were found to have taken place due to engine failure on takeoff, both due to the mix of "oddball" engines as well as endemic cooling problems. The reason this

6930-423: 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. It was named the "Truck-a-Plane" and Jim Bede was awarded a US patent for the design. After more than 5,100 kits had been delivered to prospective builders, the kits stopped shipping as well. Although

7029-448: The fuselage. Several companies were formed to help builders complete their kits, and many of the aftermarket modifications were worked into these services. As of 2015 , BD-Micro Technologies of Siletz, Oregon continues to offer kit building support, including new-build kits featuring (optionally) all of these modifications and powered by a 64 hp (48 kW) Rotax 582 or 65 hp (48 kW) Hirth 2706 two-stroke engine, and even

7128-432: 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, the company had taken over 4,300 orders, making it one of

7227-470: The introduction of the jet version of the Bede BD-5 in the 1970s that another sport aircraft like the Yak-32 was offered. Even in the 21st century, single-seat sporting jets are rarely offered by manufacturers. The light attack version of the Yak-32 was designated Yak-32Sh, and was planned to include more sophisticated avionics than the Yak-32. It could also carry external fuel and weapons loads, including

7326-459: The market primarily in kit form by the now-defunct Bede Aircraft Corporation 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-driving engine – 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

7425-533: The middle of 1973 the basic design was complete and the tooling set up for production. Now over two and a half years after the deposits started being taken, 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. Many builders took

7524-411: The most popular general aircraft projects in modern history. The prototype, N500BD , flew briefly on September 12, 1971, powered by a 36 hp (27 kW; 36 PS) Polaris Industries snowmobile engine. This was sixteen months after deposits had been taken, which led to some griping in the press. The stability of the aircraft with the original V-tail was marginal at best and clearly needed

7623-464: The opening sequence of the James Bond film Octopussy (1983). Many of these aircraft have since been involved in crashes. The loss of the Bud Light Jet was caused by an incorrectly specified fuel flow sending unit which burst in mid-flight and caused fuel to be sprayed directly into the engine compartment. The fuel ignited when it came in contact with the hot components of the engine, forcing

7722-444: The original A and B wings, with a 17 ft (5.2 m) span. An effort was made to interest Aeronca in producing the BD-5J commercially. A kit was shipped to Aeronca, but after assembling it, they declined -- reportedly because it had too many problems, and too much risk, and was too difficult to build -- and Aeronca returned the assembled craft to Bede. Bob Bishop purchased 20 BD-5J kits as soon as they had appeared, and many of

7821-467: The pilot to trade speed for altitude, climb, and bail out. The aircraft then went into a flat spin and pancaked into the ground, but was sufficiently intact to allow the cause of the fire to be determined relatively quickly. On June 16, 2006, while practicing for an air show at Carp Airport in Ottawa, Ontario , Canada, Scott Manning fatally crashed in his "Stinger Jet," one of the last BD-5Js to remain on

7920-509: The prototype starting 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 looked more like a jet fighter than a typical general aviation aircraft, with the pilot sitting in a semi-reclined position under a large fighter-like plexiglas canopy only inches above the pilot's head. Behind the cockpit

8019-559: The record for the world's smallest jet aircraft, weighing only 358.8 lb (162.7 kg). Development of the "Micro" dates back as early as 1967, when Jim Bede was inspired by the Schleicher ASW 15 . Along with his chief designer, Paul Griffin, they make preliminary designs of what would become the BD-5. At the time, however, Bede was working on the Bede BD-4 . Serious work on the Micro started in 1970, with construction of

8118-404: The result of the creation of lift on a three-dimensional lifting body , such as the wing or propeller of an airplane. Induced drag consists primarily of two components: drag due to the creation of trailing vortices ( vortex drag ); and the presence of additional viscous drag ( lift-induced viscous drag ) that is not present when lift is zero. The trailing vortices in the flow-field, present in

8217-489: The runway, buckling the nose gear. Incorrect mixture was identified as the cause of a second wreck of N501BD, in September 1972, when the mixture control broke and Berven had to execute another forced landing . This landing resulted in damage to all the gear and the fuselage as well. Since N502BD would be ready in two months, they decided not to repair N501BD , and it ended testing after about 30 hours of flight time. N502BD ran into problems of its own. Early models used

8316-555: The runway. The BD-5J has also held the Guinness record for the World's Smallest Jet for more than 25 years. 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 lb (162.7 kg) empty, 80 lb (36 kg) lighter than Bishop's and the lightest documented weight for a BD-5. As of 2002 , there were an estimated 150 BD-5s in airworthy condition. Data from Jane's All

8415-408: The shape of the object and on the Reynolds number R e = v D ν = ρ v D μ , {\displaystyle \mathrm {Re} ={\frac {vD}{\nu }}={\frac {\rho vD}{\mu }},} where At low R e {\displaystyle \mathrm {Re} } , C D {\displaystyle C_{\rm {D}}}

8514-420: The shorter "A" wing, 14 ft 3 in (4.34 m), it would be fully aerobatic and have a slightly higher top speed. Builders could optionally buy both wings, switching them in about 10 minutes. In addition to being easy to fly, the BD-5 was also intended to be easy to build and own. The fuselage was constructed primarily from fiberglass panels over an aluminum frame, reducing construction time to only

8613-808: The speed, the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, 4 times the work done in half the time requires 8 times the power. When the fluid is moving relative to the reference system, for example, a car driving into headwind, the power required to overcome the aerodynamic drag is given by the following formula: P D = F D ⋅ v o = 1 2 C D A ρ ( v w + v o ) 2 v o {\displaystyle P_{D}=\mathbf {F} _{D}\cdot \mathbf {v_{o}} ={\tfrac {1}{2}}C_{D}A\rho (v_{w}+v_{o})^{2}v_{o}} Where v w {\displaystyle v_{w}}

8712-884: The square of the speed at low Reynolds numbers, and as the cube of the speed at high numbers. It can be demonstrated that drag force can be expressed as a function of a dimensionless number, which is dimensionally identical to the Bejan number . Consequently, drag force and drag coefficient can be a function of Bejan number. In fact, from the expression of drag force it has been obtained: F d = Δ p A w = 1 2 C D A f ν μ l 2 R e L 2 {\displaystyle F_{\rm {d}}=\Delta _{\rm {p}}A_{\rm {w}}={\frac {1}{2}}C_{\rm {D}}A_{\rm {f}}{\frac {\nu \mu }{l^{2}}}\mathrm {Re} _{L}^{2}} and consequently allows expressing

8811-482: The terminal velocity v t = ( ρ − ρ 0 ) V g b {\displaystyle v_{t}={\frac {(\rho -\rho _{0})Vg}{b}}} . For a given b {\displaystyle b} , denser objects fall more quickly. For the special case of small spherical objects moving slowly through a viscous fluid (and thus at small Reynolds number), George Gabriel Stokes derived an expression for

8910-489: The velocity function is defined in terms of the hyperbolic cotangent function: v ( t ) = v t coth ⁡ ( t g v t + coth − 1 ⁡ ( v i v t ) ) . {\displaystyle v(t)=v_{t}\coth \left(t{\frac {g}{v_{t}}}+\coth ^{-1}\left({\frac {v_{i}}{v_{t}}}\right)\right).\,} The hyperbolic cotangent also has

9009-405: The wake of a lifting body, derive from the turbulent mixing of air from above and below the body which flows in slightly different directions as a consequence of creation of lift . With other parameters remaining the same, as the lift generated by a body increases, so does the lift-induced drag. This means that as the wing's angle of attack increases (up to a maximum called the stalling angle),

9108-434: The wing root airfoil, which softened the stall response of the aircraft without any significant performance degradation. The reprofile presents other unique problems, associated with the way it is applied to the wing upper surface, essentially glueing foam to the aluminum skin and covering with fiberglass. Similarly, the small center-of-gravity range has since been addressed with 5.5–13 in (14–33 cm) stretch kits for

9207-399: Was a compartment housing a two-cylinder air-cooled 40  hp (30  kW ; 41  PS ) piston engine driving a pusher propeller . For improved performance the aircraft featured both a V-tail and retractable landing gear in order to reduce drag . Calculated drag was so low that split flaps and spoilers were added to the wing in order to improve deceleration for landing. This

9306-403: Was apparently the first application of spoilers on a light aircraft. The low drag implied excellent performance; with the 40 hp engine it was expected to reach "nearly" 200 miles per hour (320 km/h), while the larger 55  hp (41  kW ; 56  PS ) engine allowed it to cruise at 200 mph with the 21 ft 6 in (6.55 m) "B" wing, and have 1,215 miles range. With

9405-412: Was due to the need to fit their selected engine into an airframe designed for the Hirth, which was no longer available. Additionally, the construction techniques had improved somewhat since early Bede designs, but fastening the panels still required drilling, deburring, dimpling, drilling again and deburring again for each rivet. With the original mixed-construction design this would not have been as much of

9504-453: Was easily addressed by making the servo tabs 50% larger. A more worrying development was that the engines all had problems with mixture due to changes in engine speed or load, which led to rough engine operation. In August, while Bede was demonstrating the BD-5 (N501BD) to the FAA in order to receive permission to fly at Oshkosh, the engine seized. On its deadstick landing , the aircraft overran

9603-549: Was expected that the larger engines would burn between 4.5 and 5.5 gallons per hour. By this point, it seemed the basic design was complete, and Bede turned his attention to other projects. One was the jet-powered BD-5J, which boosted performance to 305 knots (565 km/h; 351 mph). There was an attempt to sidestep the engine problem with the BD-5S glider (S for Sailplane), with lengthened wings and no engine, which prompted Air Progress magazine to sarcastically note, "At last,

9702-557: Was now a large order book. By December 1971, the tooling for the new fuselage was in development. The aircraft now featured a longer, more pointed nose, whereas the N500BD had been patterned on the ASW 15 and had a more rounded, egg-like shaping at the front. While this work was in progress, Bede continued to experiment with modifications to the empennage , eventually abandoning the V-tail for

9801-520: Was some time before completed BD-5s started to appear. 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 to complete kits at bargain prices. Although Bede had suggested using the B wings, the earliest kits shipped only with the short "A" wings. All four examples completed with these wings crashed on their first flight, three on takeoff, one on landing. In three of

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