History Podcasts

Kawasaki Ki-64

Kawasaki Ki-64

Kawasaki Ki-64

The Kawasaki Ki-64 was a radical design for a high-speed single-seat fighter powered by two engines both mounted in the main fuselage. The basic idea for the Ki-64 was produced by Takeo Doi, head of Kawasaki's design team, in 1939. Externally it resembled a conventional single engine single-seat fighter, but it was actually powered by two engines, one mounted in front of the cockpit and one behind. Detailed design work on the project didn't begin until October 1940. Doi adopted the Kawasaki Ha-201 engine, which despite its name was actually two Ha-40 licence built DB601A engines, each powering one of the contra-rotating propellers. The rear engine powered the controllable-pitch forward propeller, while the forward engine powered the fixed-pitch rear propeller.

Engine cooling was provided by a steam vapour system which used surface condensers mounted on the wings and flap surfaces, combined with a small retractable radiator for use while on the ground. This system was initially tested on a Ki-61-I, before being installed in the only Ki-64 prototype. The wing based cooling system reduced drag, increasing speed by 25mph, and was less vulnerable to damage, but it also reduced the amount of space available in the wings for fuel tanks.

The prototype was completed in December 1943. On the fifth test flight the rear engine caught fire, forcing an emergency landing. The engines and the airframe were separated for repairs, and never reunited. A modified design, the Ki-64 KAI, was suggested, powered by a 2,800hp Ha-201 engine and using electrically operated constant speed contra-rotating propellers. This second design was never built.

Engine: One Kawasaki Ha-201 ([Ha-72] 11) twenty-four cylinder inverted-vee liquid cooled engine made up of two Ha-40 engines paired
Power: 2,350hp at take-off, 2,200hp at 12,795ft
Propellers: Three-blade contra-rotating propellers
Crew: 1
Wing span: 44ft 3 1/2in
Length: 36ft 2 1/4in
Height: 13ft 11 5/16in
Empty Weight: 8,929lb
Loaded Weight: 11,244lb
Max Speed: 429mph at 16,405ft
Service Ceiling: 39,370ft
Range: 621 miles
Armament: Two 20mm Ho-5 cannon in fuselage decking, two 20mm Ho-5 cannon in wings


試作高速戦闘機 / shisaku kōsoku sentōki / prototyp vysokorychlostní stíhačky
Allied Code Name: "Rob"

Historie a vývoj:

Společnost 川崎航空工機業株式会社 - Kawasaki Kōkūki Kōgyō Kabushiki Kaisha (dále jen Kawasaki) vedla v roce 1939 poměrně úspěšná jednání s německou továrnou Daimler-Benz ve Stuttgartu, cílem těchto jednání bylo získat vedle nákupu několika desítek motorů DB-601 i práva na jejich licenční výrobu. Tato společnost byla již delší dobu zastáncem a propagátorem řadových motorů a snažila se, aby velení císařského armádního letectva (大日本帝国陸軍航空本部 Dai-Nippon Teikoku Rikugun Kōkū Hombu) svolilo k jejich co možno nejširšímu použití, poukazovala přitom na evropské konstrukce stíhacích letadel a na první zprávy z prvních, zde probíhajících bojů. Tovární konstrukční tým včele s šéfkonstruktérem Takeo Doiem se po dokončení stavby prototypu těžké stíhačky Kawasaki Ki-45 začal připravovat na projekty možných stíhacích letadel poháněných těmito motory. V únoru 1940 se konečně Rikugun Kōkū Hombu rozhodlo a objednalo u společnosti Kawasaki vývoj a stavbu prototypů přepadové stíhačky Ki-60 a stíhacího letounu Ki-61 s „japonštějšími“ vlastnostmi. Inženýr Takeo Doi a jeho konstrukční tým okamžitě začali na těchto projektech pracovat, ale samotný šéfkonstruktér se již od roku 1939 zabýval myšlenkou na stavbu vysokorychlostního stoje poháněného vysokovýkonným řadovým motorem, dovedeného k co možné nejvyšší aerodynamické dokonalosti. Takeo Doi získal podporu představenstva společnosti a tak mohl začít pracovat na projektu tohoto letounu.

Rikugun Kōkū Hombu o tomto projektu vědělo, protože u každého výrobce, který dostával armádní zakázky, byl styčný důstojník (přidělenec), který dohlížel na chod továrny. Rikugun Kōkū Hombu tedy o tomto projektu vědělo, ale neprojevilo o něj žádný zájem. Veškeré výpočty a projektové práce tak probíhaly v režii společnosti Kawasaki, představenstvo společnosti se snažilo, aby případnou stavbu prototypu financovala armáda a tak prostřednictvím dohlížejícího armádního důstojníka seznámilo zástupce letectva s vypočtenými výkony (maximální rychlost vypočtena na 700 km/h). Zároveň začalo lobovat ve prospěch projektu s tím, že se může jednat o rychlý stíhací letoun. Tato snaha byla nakonec korunována úspěchem a v listopadu 1940 Rikugun Kōkū Hombu předalo společnosti Kawasaki objednávku na stavbu prototypu, při té příležitosti bylo projektu přiděleno označení Ki-64.

Zcela zásadním předpokladem pro vypočtené vysoké výkony a zejména velké hodnoty maximální rychlosti byl výkonný motor a dokonalé aerodynamické zpracování. S ohledem na skutečnost, že ani nový motor nepodával potřebný výkon, šel Takeo Doi dosti nevšední cestou, pro pohon rychlostního letounu potřeboval motory dva, ale klasická konstrukce dvoumotorového letounu nebyla příliš vhodná z pohledu aerodynamiky, velký čelní odpor obou motorů v křídlech a trupu by eliminoval výkon dvou motorů, proto Doi navrhl letoun, který vypadal jako jednomotorový, ale motory byly v trupu tandemově uloženy. Japonci tuto sestavu motorů označili jako Ha-201, ale šlo vlastně o dva samostatné motory namontované před a za pilotní kabinu, spojené hřídelí. Jednalo se o dva licenčně vyráběné řadové invertní dvanáctiválce Daimler-Benz DB-601A, které armádní letectvo označovalo Ha-40. Celá takto vzniklá sestava dávala při měření na brzdě výkon 2 350 koní, v letadle tato pohonná jednotka roztáčela dvě souosé trojlisté protiběžné vrtule, přední motor poháněl zadní nestavitelnou vrtuli a zadní motor zase vrtuli přední, stavitelnou. Tak vznikl sice větší, ale stále aerodynamicky výhodný celokovový dolnoplošník. Doi vše podřídil aerodynamice - křídla měla profil umožňující laminární proudění, jejich nízký aerodynamický odpor nezvyšovaly žádné chladiče kapaliny. Absence chladičů kapaliny byla umožněna použitím systému kondenzačního chlazení. Chladící plochou byl takřka celý povrch křídla a to včetně klapek. Pravá strana byla určena pro chlazení zadního motoru a levá ochlazovala motor přední. V křídlech byly také nádrže paliva, které pojaly 470 litrů paliva. Do každé poloviny křídla byl nainstalován jeden kanón Ho-5 ráže 20 mm i se zásobou střeliva. Instalace těchto zbraní byla provedena, dle mého názoru jen proto, aby bylo možno odůvodnit zařazení rychlostního letounu do kategorie stíhacích letadel. Nedovedu si představit stíhačku, u které by pouhý průstřel křídla znamenal vyřazení letounu z boje. Letoun Kawasaki Ki-64 tak byl spíše ozbrojeným experimentálním rychlostním letounem.
Vývoj se protahoval, bylo to způsobeno jednak malou prioritou, ale zejména pro předpokládané problémy s chlazením motorů, chladící soustavě tovární technici věnovali mnoho úsilí, společně s konstruktéry se podařilo najít řešení, které mělo být dostatečně účinné. V prosinci roku 1943 byl letoun připraven k zahájení zkoušek. Letů vykonal celkem pět, ale při pátém letu došlo k přehřátí a následnému zadření zadního motoru. Po přistání byla celá pohonná jednotka demontována včetně chlazení a byla odeslána motorářům společnosti Kawasaki. To však znamenalo definitivní konec zkoušek, ke zpětné zástavbě pohonné jednotky již nedošlo, motor zůstal v továrně v Akashi. Tam byl po kapitulaci objeven americkou technickou zpravodajskou jednotkou a byl shledán natolik zajímavým, že byl dopraven do USA. Neexistují žádné záznamy o jeho zkouškách a je otázkou, zda byl Američany vůbec zkoušen. Drak letounu byl spojeneckou komisí nalezen v září 1945 v Gifu, zde zpravodajci zpětně tomuto stroji přidělili kódové jméno - Rob.

Z konstrukčního hlediska byl Rob jistě velmi zajímavou konstrukcí, která slibovala dosažení vysokých výkonů, pokud by však měl být použit jako stíhací letoun, byla by jeho použitelnost v boji dosti sporná, ostatně na značnou zranitelnost chladícího systému poukazovalo i velení armádního letectva. V případě, že by byl letoun přijat do výzbroje, plánovala se zástavba dalšího páru kanónů nebo kulometů (Ho-103) nad přední motor, jejich palba by byla synchronizovaná s otáčkami protiběžných vrtulí.

Takeo Doi pracoval ještě na projektu výkonnější verze Ki-64 Kai, pohonná jednotka tohoto stroje měla dosahovat výkonu až 2800 koní a měla pohánět souosé protiběžné vrtule, obě však měly být plně stavitelné, maximální rychlost měla dle provedených výpočtů až dosahovat hodnoty 800 km/h.


Kawasaki Ki-64 Experimental Fighter

In the late 1930s, designers at Arsenal de l’Aéronautique in France began working on a new fighter powered by two engines installed in tandem. One engine was positioned in front of the cockpit, and the other engine was behind the cockpit. Each engine drove half of a coaxial contra-rotating propeller. This design was eventually developed into the Arsenal VB 10. Takeo Doi was a Japanese designer at Kawasaki and was aware of Arsenal’s tandem-engine design.

The Kawasaki Ki-64 fighter undergoing gear retraction tests in a hangar in Gifu. Note the exhaust stacks for the front engine and the dorsal air intake scoop for the rear engine.

Doi was also aware of the evaporative cooling system used on the German Heinkel He 100. Japan had sent a delegation to Germany in December 1938 that successfully negotiated the purchase of three He 100 and two He 119 aircraft. The He 100s were delivered to Japan in the summer of 1940.

In 1939, Doi began to contemplate a high-speed fighter for the Imperial Japanese Army Air Force that used tandem engines and evaporative cooling. At the time, the Japanese aircraft industry was more focused on conventional aircraft, and Kawasaki and Doi were busy with designing the Ki-60 and Ki-61 Hien (Swallow, or Allied code name “Tony”) fighters. In October 1940, Kawasaki and Doi received support for the tandem-engine fighter project, which was then designated Ki-64 (Allied code name “Rob”). The aircraft’s design was refined, and a single Ki-64 prototype was ordered on 23 January 1941.

The Kawasaki Ki-64 looked very much like a continuation of the Ki-61 design, and while some of its features were inspired by other aircraft, the Ki-64 was an entirely independent design. The single-seat aircraft had a taildragger configuration and was of all-metal construction. Although designed as a fighter, the Ki-64 was primarily a research aircraft intended to test its unusual engine installation and evaporative cooling system. Proposed armament included one 20 mm cannon installed in each wing and two 12.7 mm machine guns or 20 mm cannons installed in the upper fuselage in front of the cockpit. The armament was never fitted to the prototype.

The Ki-64 appears to be preparing for an early test flight. The front engine’s intake scoop can be seen just above the exhaust stacks. Note the exhaust stains from the front engine and that the lightning bolt has not yet been painted on the fuselage.

The Ki-64 was powered by a Kawasaki Ha-201 (joint designation [Ha-72]11) engine that was comprised of two Kawasaki Ha-40 inverted V-12 engines coupled to a coaxial contra-rotating propeller. The Ha-40 (joint designation [Ha-60]22) was a licensed-built Daimler-Benz 601A engine and had a 5.91 in (150 mm) bore, a 6.30 in (160 mm) stroke, and a displacement of 2,070 cu in (33.9 L). As installed in the Ki-64, the shaft for the rear engine extended under the pilot’s seat and through the Vee of the front engine to the propeller gearbox. The rear engine drove the front adjustable-pitch propeller of the contra-rotating unit. The front engine drove the rear fixed-pitch propeller. Each set of propellers had three blades that were 9 ft 10 in (3.0 m) in diameter. The Ha-201 displaced a total of 4,141 cu in (67.9 L) and produced 2,350 hp (1,752 kW) at 2,500 rpm for takeoff and 2,200 hp (1,641 kW) at 2,400 rpm at 12,795 ft (3,900 m). Each engine section could operate independently of the other.

The engine sections had separate evaporative cooling systems. Heated water from the engine at 45 psia (3.1 bar) was pumped to a steam separator, where the water pressure dropped to 25 psia (1.7 bar), and about 2% of the water flashed to steam. The steam was then ducted at 16 psia (1.1 bar) through panels in the wings, where it was cooled and condensed back into water. The water then flowed back into the engine. The evaporative cooling system eliminated the drag of a radiator, and this enabled the aircraft to achieve higher speeds. It was believed that battle damage would not be much of a problem for the cooling system. The low pressure of the steam combined with steam’s low density meant that the amount of coolant lost through a puncture would be minimal, and the separate engines and cooling systems helped minimize the risk of a forced landing if damage did render one system ineffective.

The evaporative cooling system for the front engine was housed in the left wing, and the rear engine’s system was housed in the right wing. Each system consisted of two steam separators, an 18.5-gallon (70 L) tank in the wing’s leading edge near the fuselage, four upper and four lower wing condenser panels, an upper and lower condenser section in the outer flap, and a water tank in the fuselage. Sources disagree regarding the size of each fuselage tank, but combined, the tanks held around 52.8 gallons (200 L). Suspended below the right wing was a scoop that held oil coolers for the engines.

Another image of the Ki-64 doing a ground run. Note the aircraft’s resemblance to a Ki-61 Hien. Exhaust for the rear engine was collected in a manifold that exited the fuselage just above where the trailing edge of the wing joined the fuselage. That exhaust exit can just barely be discerned in this image.

The Ki-64 had a 44 ft 3 in (13.50 m) wingspan and was 26 ft 2 in (11.03 m) long. The aircraft had a top speed of 435 mph (700 km/h) at 13,123 ft (4,000 m) and 429 mph (690 km/h) at 16,404 ft (5,000 m). The Ki-64 could climb to 16,404 ft (5,000 m) in 5.5 minutes and had a service ceiling of 39,370 ft (12,000 m). Since the wings housed the cooling system, little room was left for fuel tanks. Each wing had a 22-gallon (85 L) fuel tank, and an 82-gallon (310 L) tank was housed in the fuselage this gave the Ki-64 a 621 mile (1,000 km) range. The aircraft weighed 8,929 lb (4,050 kg) empty and 11,244 lb (5,100 kg) loaded.

While the Ki-64 was being built, a Ki-61 was modified to test the evaporative cooling system. With its radiator removed and evaporative panels added to its wings, the modified Ki-61 first flew in October 1942. Around 35 flights were made before the end of 1943, and they served to develop and refine the cooling system. The aircraft proved the validity of the evaporative cooling system and achieved a speed 25–30 mph (40–48 km/h) in excess of a standard Ki-61. However, the evaporative cooling system did require much more maintenance than a conventional system.

The Ki-64 was completed at Kawasaki’s plant at Gifu Air Field in November 1943. The aircraft underwent ground tests that revealed a number of issues. By December, the issues were resolved enough for flight testing to commence. The aircraft made four successful flights, but the rear engine caught fire on the fifth flight. The pilot was able to make an emergency landing at Kakamigahara, but the rear engine and parts of the rear fuselage and cooling system had been damaged. The Ha-201 engine was sent to Kawasaki’s engine plant in Akashi for overhaul, and the Ki-64 airframe was sent back to Gifu for repairs.

A poor image, but perhaps the only one, showing the Ki-64 in flight. The lightning bolt has been painted on the fuselage.

The short flying career of the Ki-64 had shown that its cooling system was insufficient. The system worked well for level flight, but it was inadequate for ground running, takeoff, and climb. When the system was overloaded, steam was not condensed back to water and was subsequently vented overboard via a 16 psi (1.1 bar) relief valve. The cooling system lost about 12 gallons (45 L) of water during a rapid climb from takeoff to 18,000 ft (5,500 m). Water freezing within the system, either while in flight or on the ground during cold temperatures, was another concern. Adding an alcohol mixture to the water coolant was a possible solution, but the Ki-64 never underwent any cold weather testing.

While undergoing repairs, the Ki-64 was to be modified and redesignated Ki-64 Kai. The existing propellers would be replaced with fully adjustable and feathering contra-rotating propellers, which would make it easier for one engine to be shut down in flight. The engines were to be replaced with more powerful Ha-140s (joint designation [Ha-60]41), each of which was capable of 1,500 hp (1,119kW). The coupled engine was designated Ha-321 (joint designation [Ha-72]21) and produced 2,800 hp (2,088 kW). With the changes, it was estimated that the Ki-64 Kai would have a top speed of 497 mph (800 km/h). However, the propeller and engines were delayed by more pressing war-time work, and the Ki-64 program was cancelled in mid-1944.

The Ki-64 airframe remained at Gifu where it was captured by American forces in 1945. Various parts of the cooling system were removed from the aircraft and shipped to Wright Field in Dayton, Ohio for further analysis and testing. The remainder of the Ki-64 was eventually scrapped.

The K-64 as discovered by American forces at the end of World War II. The engines had been removed, and the aircraft was in a rather poor state. Note the canopy frame sitting on the wing.

Sources:
Japanese Army Fighters Part 1 by William Green and Gordon Swanborough (1977)
Japanese KI-64 Single Fighter with Two Engines in Tandem and Vapor-Phase Cooling, Air Technical Intelligence Review Report No. F-IR-100-RE by Petaja and Gilmore (31 July 1946)
Japanese Secret Projects by Edwin M. Dyer III (2009)
Japanese Aircraft of the Pacific War by René J. Francillon (1979/2000)
Encyclopedia of Japanese Aircraft 1900–1945 Vol. 4: Kawasaki by Tadashi Nozawa (1966)
The Xplanes of Imperial Japanese Army & Navy 1924–45 by Shigeru Nohara (1999)
Heinkel He 100 by Erwin Hood (2007)


The First Kawasaki Dirt Bike

1963 Kawasaki B8-M

The 1963 Kawasaki B8-M, (the ‘Red-Tank Furore’) a motocross version of the B8 street machine was the first production motocross machine from Japan.

The B8-M was the start of the Kawasaki dirt bike legacy which evolved into the long-running KX motocross series.

It featured a 123cc rotary-valve two-stroke single-cylinder engine with a four-speed manual clutch transmission. In transforming the bike into a motocrosser, the engineers removed the lights, raised the expansion chamber, upgraded the forks, changed the seat and handlebars, and added knobby tires.

The engine boasted 12 horsepower and the bike was so successful it took a clean sweep of the top six places in the All-Japanese Motocross Championships in 1963.

1968 Kawasaki F21M

1969 Kawasaki F21M Green Streak

In 1968 the Kawasaki F21M was released. Unlike the B8M it was not based on a street bike but was designed from the ground up for scrambles racing, a tamer off-road version of motocross.

It was a 238cc rotary-valve single-cylinder two-stroke with a four-speed transmission that boasted 28 horsepower, impressive by 1968 standards.

In 1969 the F21M gained a new name and a new color. The red tank was gone and the ‘Green Streak’ was the first Kawasaki to be produced in the now-famous Kawasaki lime green.

1970 Kawasaki G31M Centurion

1970 Kawasaki GM31 Centurion

During the late sixties, motocross in America was gaining in popularity. Kawasaki began its US operations in 1966 and by 1968 had dealerships nationwide.

Kawasaki’s high-performance street machines were popular among the road bike crowd, but the off-road sector was still lagging behind.

In 1970 the Kawasaki G31M Centurion turned all that around. It was a 100cc rotary-valve single that pumped out a whopping 18.5 horsepower, nearly double that of other 100cc bikes of the day.

Like the F21M it was not designed specifically for motocross, but could easily be modified for competition. It was an extremely high revving engine and began winning races across America.

The G31M Centurion stands out as the bike that put Kawasaki on the US racing radar for the first time.

1974 Kawasaki KX250

1974 Kawasaki KX250

The 1974 Kawasaki KX250 marks the very first production year of the KX series. It was Kawasaki’s most serious off-road commitment to date and their first motorcycles designed specifically for motocross racing.

The bike featured a chrome-moly steel frame when most of the other Japanese brands of the day were still using mild steel. The 250cc piston-port two-stroke engine had a five-speed gearbox and wet clutch.

The suspension featured 5.8 inches of travel up front, and 3.5 inches at the rear, fairly standard for bikes of the day.

Even though the KX had a hard time keeping up with the Honda Elsinore CRs and the Yamaha YZ of that year, it was a significant shift for Kawasaki towards more competitive racing machines.

The KX line is one of the most successful in motocross today, and it started here with the 1974 KX250.

1978 Kawasaki KX250 A-4

1978 Kawasaki KX250

With Honda, Yamaha, and Suzuki taking turns to dominate the 250cc motocross scene, Kawasaki did not even produce a motocross machine in 1977. Most Kawasaki dealerships were more interested in selling the very popular Z-1000 street machines.

In 1978 all that changed with the release of Kawasaki’s first official ‘works-replica’ KX250 A-4. The bike was a lightweight 206 pounds and produced a staggering 40 horsepower. It was the first Long-travel suspension KX, with power and handling targeted at expert racers only.

The A-4 was available in limited numbers with only about 1500 produced. It was more about demonstrating Kawasaki’s commitment to racing than big sales and the A-4 proved that. It put Kawasaki back in the game with the other Big-Four Japanese manufacturers.

1979 Kawasaki KX80

1979 Kawasaki KX80

In 1979 Kawasaki entered the growing mini motocross arena for the first time with the release of the Kawasaki KX80. It was a very torquey 80cc two-stroke with a five-speed transmission and rugged long-travel suspension.

It was slightly larger than the other 80s of the time, and the KX80 gave Kawasaki a foothold into the booming entry-level market.

The KX80 was a huge success and introduced a generation of young riders to the green machines, paving the way for what would be the most successful amateur motocross program in motocross history, ‘Team Green’.

1980 Kawasaki KX250

In the late seventies, long-travel motocross suspension was advancing in leaps and bounds with all the manufacturers caught up in developing their own new suspension technology.

During a five-year period, suspension travel had grown from the once-standard 3 inches to a full 11 to 12 inches by 1979. Focus then began to shift to refining the quality of that amount of travel.

1981 Kawasaki KX250 with Uni-Trak linkage suspension

The 1980 Kawasaki ‘Uni-Trak’ was the first production single shock design to utilize a linkage system. Originally named the ‘Bell Crank’ the design consisted of a large vertically mounted single shock connected in a see-saw arrangement to a bell crank by a set of steel pull rods and bolted to the alloy swingarm.

The design intention was to provide better small bump performance, while still giving bottoming resistance on the big hits, thereby fine-tuning the performance. While the Uni-Trak system wasn’t a huge improvement over the dual-shock setups at the time, it did show there was potential in the new design.

In the years to follow, there were improvements made, and the heavy steel components were replaced with lighter alloy alternatives. The 1980 Kawasaki Uni-Trak certainly did pave the way for the linkage systems that have become standard with all manufacturers today.

1982 Kawasaki KX125 & KX250

In 1982 Kawasaki became the first major manufacturer to introduce disc brakes to dirt bikes. With advances in power and suspension, it was soon evident that drum brakes no longer had the stopping power required by modern motocross machines.

Kawasaki first debuted their disc brakes on their 1980 factory racers in the All-Japanese Nationals. There were development problems along the way, but by 1982 the new braking system was introduced on the KX125 and KX250.

Riders found that the braking power was something that they had to become accustomed to as braking that required four fingers could now be achieved with just one finger.

The rest is history and from then on the days of the drum brakes were numbered.

The KDX Series

1988 Kawasaki KDX200

The Kawasaki KDX 200 was one of the most popular two-stroke enduro models of the 80s. Its production ran from 1983 to 2006.

Launched in 1980 as a 175cc, the original KDX175 introduced the Uni-Trak monoshock suspension. The emphasis was on affordability and fun. It was a race-capable two-stroke trail bike that was as reliable as any bike could get.

In 1983 it evolved into the KDX200. The move wasn’t surprising since the AMA class displacement range changed to ‘126 – 200cc’. The additional 25cc made a huge difference in performance.

It competed in the same realm as the Suzuki PE175 and the Yamaha IT175 which suffered from a lack of horsepower, so the KDX200 became the king of the class.

The 200cc engine delivered ample power at low revs, which made the bike easy to ride, but when the bike hit midrange and ‘came on the pipe’ the power was impressive.

The KDX engine remained air-cooled until 1989. The big advantage of air cooling being weight saving. The lack of radiators, coolant pumps, and the associated plumbing all contributed to its light dry weight of 207 pounds.

The KDX handling and suspension was a curious mix. Test reviews at the time concluded that the suspension components were nothing special, but the chassis design took the KDX to the top of its class.

The wheelbase was two inches longer than most of the competition, which made the bike stable at high speeds but combined with the fork angle and the Uni-Trak rear suspension, this allowed the bike to turn quickly and easily under any conditions.

For the first three years the KDX came out with the “A” series model designation – A1 through to A3. (1983-1985)
The letter designation was a little confusing to the consumer, the next series was the 1986 KDX200 C1: there was no “B1.”

The “C” series (1986-1988) included some interesting upgrades. The engine remained air-cooled, but the KIPS valve (Kawasaki Integrated Powervalve System) was introduced which increased low-end and mid-range power slightly.

A welcome improvement of the C1 was the addition of a disc front brake. Most enduro and trail bikes of the mid-80s had drum brakes front and rear, so the disc front brake was a significant improvement. The KDX did not get the rear disc brake for a few more years.

Suspension upgrades included new 43mm Kayaba conventional forks with 10.6 inches of travel. The increased flex-resistance improved steering accuracy. The rear shock was improved with a multi-adjustable aluminum-bodied Kayaba increasing the rear suspension travel to 11.4 inches.

The “E” series (1989-1994) came after 3 years of “C” series KDX bikes. The E1 featured the first liquid-cooled KDX200 engine and a rear disc brake, lifting it to the level of the motocrossers of the day.

Handling was excellent due to the KX125 chassis, though still a little soft at high-speed sections. Suspension stroke was increased by a quarter-inch front and rear.
The KDX was slowly turning into more of a race bike.

The final “H” series (1995-2006) was significant for its new KX-style perimeter frame. There were so many changes on the H1 that it was considered a completely new bike, and finally moved it into the realm of a race bike.

The liquid-cooled engine was completely new. A new style powervalve was used, and the engine had higher compression, a new crank, and a bigger clutch.

The seat height was taller due to the new frame, and the fuel tank was smaller. The KDX still rode like a KDX, was stable on the tight woody trails, and was very well received. Magazine tests of the day questioned what could possibly be done to improve the 1995 KDX.

It received very few changes until its run ended in 2006. It was a 26 year run for Kawasaki’s most successful two-stroke trail bike.

Kawasaki introduced the all-new KDX220A4 in 1997, presumably to compete with the 250cc competition, but the 220 felt slower than the 200. It could be made faster with a lot of work, but its existence cut into the market of the established KDX200 and hastened the demise of both machines.

The move toward four-stroke motocross bikes and uncertainty over the future viability of two-stroke dirt bikes reduced the sales of the KDX, and it was discontinued to make way for the KLX series of four-stroke trail bikes.

1984 Kawasaki KLR250

1984 Kawasaki KLR250

The Kawasaki KLR250 was produced from 1984 to 2005 as the successor to the KL250C which ran from 1978 to 1983. It had a 250cc four-stroke DOHC four-valve engine and 6-speed transmission, with both electric and kick start.

This lightweight dual-sport bike was used by the US military like its bigger brother the KLR650 for tasks like messenger duty and reconnaissance. It was also used extensively by the Chilean National Police.

It was never intended as an enduro machine, but when used as it was designed it was a robust and reliable bike. The KLR250 was discontinued at the end of 2005 and was replaced by the KLX250S in 2006.

1987 Kawasaki KLR650

1987 Kawasaki KLR650

The Kawasaki KLR650 is a long-standing model in Kawasaki’s line which remained almost unchanged from 1987 until 2008 when it received its first significant redesign.

It was billed as a ‘Triple-Sport’ in its early days, good for street, dirt, and touring. It is a 650cc single-cylinder four-stroke DOHC water-cooled adventure touring bike. It has stood the test of time making journeys across multiple countries and entire continents giving riders very little trouble.

The 2008 updates included more horsepower (36BHP), modern dual headlights, an updated instrument panel and fairing, suspension and brake upgrades, and a new swingarm.

The US military used KLR650s modified to burn military-spec fuels including diesel. The bike has proven itself to be reliable, mostly bulletproof, reasonably comfortable, and cheap. The KLR650 is even available in a Camo version.

Kawasaki sadly ceased production in 2018 after a 32-year run.

1990 Kawasaki KX125 & KX250

The Kawasaki KX motocrossers in 1989 had become outdated-looking bikes compared to the Honda, Suzuki, and Yamahas of that year.

That all changed in 1990 with the release of the all-new KX125 and KX250. The 1990 models featured all-new bodywork, steel perimeter frames, bolt-on alloy shock towers, and colorful graphics. They were an immediate hit with the motocross buying public.

Their on-track performance was very good, the 250 was one of the fastest motors on the track and the new chassis provided new levels of rigidity. The suspension also performed well and both the 125 & 250 were at the top of their class.

The 1990 KX’s had a significant impact on motocross in the early to mid-nineties with the rigid steel perimeter frames being the forerunner to the alloy perimeter frames used on all Japanese motocrossers today.

Kawasaki demonstrated once again their commitment to keep pushing the boundaries of design and technical innovation.


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Kawasaki Surname History

The surname Kawasaki was first found in the Heian period, when members of the higher classes first began to assume surnames that were based on their occupations, their cities of origin, or a local feature of their places of residence. The name Kawasaki was most likely originally assumed by someone living near the edge of a river. The aristocratic Kawasaki family was instrumental during this early period, playing a major role in the development of a uniquely Japanese culture.

PDF Surname History (Letter Size)

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Early History of the Kawasaki family

This web page shows only a small excerpt of our Kawasaki research. Another 94 words (7 lines of text) are included under the topic Early Kawasaki History in all our PDF Extended History products and printed products wherever possible.

Kawasaki Spelling Variations

Spelling variations of this family name include: Kawasaki, Kawasacki, Kawasacky and others.

Early Notables of the Kawasaki family (pre 1700)

More information is included under the topic Early Kawasaki Notables in all our PDF Extended History products and printed products wherever possible.

Migration of the Kawasaki family

Some of the first settlers of this family name or some of its variants were: Kamejiro Kawasaki, who emigrated from Shiga to the United States in 1905 Kansuke Kawasaki, a native of Hiroshima who settled in Nevada in 1907 and Jitsuichi Kawasaki, who was recorded in Salt Lake City, Utah in 1924..


Engineering:Kawasaki Ki-64

The Kawasaki Ki-64 (Allied code name: Rob) was a one-off prototype of an experimental heavy, single seat, fighter. It had two unusual design features. First it had two Kawasaki Ha-40 engines in tandem one in the aircraft nose, the other behind the cockpit, both being connected by a drive shaft. This combination (called the Kawasaki Ha-201) drove two, three-bladed, contra-rotating propellors. Ώ] ΐ] The second feature was the use of the wing surface as a radiator for the water-cooled engines. Α] The aircraft first flew in December 1943. During the fifth flight, the rear engine caught fire and while the aircraft made an emergency landing, it was damaged. The aircraft was subsequently abandoned in mid-1944 in favour of more promising projects. The airframe survived the war, and parts of the unique cooling system were sent to Wright Field for examination. Β]


Kawasaki Ki-64

From Wikipedia the free encyclopedia

Ki-64
Role Fighter
Manufacturer Kawasaki Kōkūki Kōgyō K.K.
First flight December 1943
Status Cancelled 1944
Primary user Imperial Japanese Army
Number built 1

The Kawasaki Ki-64 (Allied code name: Rob) was a one-off prototype of an experimental heavy, single seat, fighter. It had two unusual design features. First it had two Kawasaki Ha-40 engines in tandem one in the aircraft nose, the other behind the cockpit, both being connected by a drive shaft. This combination (called the Kawasaki Ha-201) drove two, three-bladed, contra-rotating propellors. Ώ] ΐ] The second feature was the use of the wing surface as a radiator for the water-cooled engines. Α] The aircraft first flew in December 1943. During the fifth flight, the rear engine caught fire and while the aircraft made an emergency landing, it was damaged. The aircraft was subsequently abandoned in mid-1944 in favour of more promising projects. The airframe survived the war, and parts of the unique cooling system were sent to Wright Field for examination. Β]


Opis konstrukcji

Kawasaki Ki-64 był jednomiejscowym, jednosilnikowym dolnopᐪtem o konstrukcji całkowicie metalowej [2] . Samolot miał klasyczne podwozie z koᐮm ogonowym, podwozie główne było wciągane w locie [2] . Kabina pilota byᐪ zamknięta [2] .

Napᆝ stanowiły dwa, 12-cylindrowe, chłodzone wodą silniki Kawasaki Ha-20 pracuj𐗎 jako jedna jednostka napᆝowa o łၜznej mocy 2350 KM na wysokoᖼi morza (2200 KM na wysokoᖼi 3900 m n.p.m.), silnik napᆝzał dwa trzypᐪtowe śmigᐪ w uk𔊭zie przeciwbieżnym [2] . Oba silniki znajdowały się w centralnej częᖼi kadłuba, jeden silnik znajdował się przed kabiną pilota, a drugi silnik był położony za kokpitem [1] . Przednie śmigło o zmiennym skoku napᆝzane było przez tylny silnik, a tylne śmigło o stałym skoku napᆝzane było przez przedni silnik [1] .

Samolot miał bardzo nietypowy system chłodzenia silników, który używał prawie caᐮj powierzchni skrzydeł i klap jako radiatora [1] . Do chłodzenia silników używana byᐪ woda, w ka៍ym skrzydle znajdował się 70-litrowy zbiornik, a łၜzna powierzchnia skrzydeł używana jako radiator wynosiᐪ 24 metry kwadratowe [1] . Przedni silnik miał chłodnicę na lewym skrzydle, a tylny na prawym [1] . Skrzydᐪ o zmodyfikowanym profilu laminarnym zawierały tak៎ zbiorniki z paliwem [1] .

Samolot mierzył 11,03 m długoᖼi, rozpiętość skrzydeł wynosiᐪ 13,5 m, a jego wysokość 4,25 m, powierzchnia skrzydeł wynosiᐪ 28 metrów kwadratowych, obcią៎nie powierzchni skrzydeł wynosiło 182 kg/m 2 [2] . Masa wᐪsna samolotu wynosiᐪ 4050 kg, a masa startowa 5100 kg [2] . Samolot osiągał prᆝkość 590 km/h na wysokoᖼi 5000 m, wejᖼie na tę wysokość zabierało mu 5 minut i 30 sekund [2] . Puᐪp maksymalny wynosił 12,000 m, a zasięg 1000 km [2] .

Uzbrojenie samolotu sk�ło się z czterech dziaᐮk Ho-5 kalibru 20 mm dwa znajdowały się w dolnej częᖼi kadłuba pod nosem oraz po jednym w ka៍ym skrzydle [2] .


Union Pacific 4-8-8-4 Big Boy Locomotive

For some time, locomotives of the Union Pacific Railroad (UP) had struggled to climb the Wasatch mountains between Ogden, Utah and Green River, Wyoming. This 176-mile (283-km) stretch of track started out at 4,300 ft (1,310 m) above sea level in Ogden, climbed the Wasatch Range to 7,300 ft (2,225 m) at the Aspen Tunnel, and then dropped to 6,100 ft (1,859 m) at Green River. Occasionally, up to three helper engines were used to assist heavily loaded trains over the Wasatch mountains.

Union Pacific Big Boy 4012 hauling a load of freight through Green River, Wyoming in November 1941. This may have been the recently delivered engine’s first trip west. (Otto Perry image via Denver Public Library)

In 1940, UP was enjoying a period of expansion, and its president, William Jeffers, was interested in a new locomotive that could conquer the Wasatch Range pulling 3,600 tons (3,266 t) unassisted. At the same time, World War II was on the horizon, and the United Sates had begun to increase its production of war material. This put even more traffic on the heavily-traveled Oden-Green River route. Headed by Otto Jabelmann, UP’s Department of Research and Mechanical Standards (DoRMS) in Omaha, Nebraska calculated that 135,000 lbf (600.5 kN) of tractive effort was needed for the engine to achieve its design goal. DoRMS quickly designed the new, massive locomotive and worked closely with the American Locomotive Company (ALCO), the company that agreed to build the engine. The engines were assigned numbers in the 4000-class, and there were plans to name the new series “Wasatch.” However, a worker wrote “Big Boy” in chalk on the front of the first engine while it was being built, and the name stuck. With its tender, the Big Boy was one of the largest and heaviest steam locomotives ever built.

The Big Boy’s design was based closely on the UP’s 4-6-6-4 Challenger that went into service in 1936. However, the Big Boy was larger and heavier than the Challenger and necessitated that UP make many changes to the track between Ogden and Green River. Heavier rail was laid in many places, and curves were realigned and adjusted to maintain a constant curvature. At stations, larger turntables were installed to accommodate the Big Boy’s length. The Big Boy was essentially the largest thing that could normally operate on an existing standard gauge railroad.

The crew standing next to newly-completed Big Boy 4002 gives scale to every part of the engine: the cylinders, wheels, boiler, etc. The railing on the front of the -1 class engines was originally coolers for the air pump. The -2 class used a standard Wilson aftercooler, as the custom set up on the Class -1 would often crack. As the coolers failed on the -1 class, they were removed and replaced by Wilson units. (Union Pacific image)

The Big Boy utilized a 4-8-8-4 wheel arrangement and was the only locomotive to do so. At the front of the engine was a four-wheel leading truck that had 36 in (.91 m) wheels. This was followed by eight 68 in (1.73 m) drive wheels, with a single piston driving a set of four wheels on each side of the engine. Another set of eight drive wheels followed that were identical to the first. Finally, under the cab was a four-wheel trailing truck with 42 in (1.07 m) wheels. The leading truck and first eight drive wheels were attached to a separate frame than the second set of drive wheels and trailing truck. Between the two sets of drive wheels was a tongue and groove pivot point that allowed the front frame to articulate independently of the rear frame. Mounted to the rear frame was the boiler, firebox, and cab. The articulated locomotive was pioneered by Swiss engineer Anatole Mallet and could handle tighter curves than a standard rigid locomotive. In the case of a long locomotive like the Big Boy, articulation allowed the engine to operate on tracks with curves as sharp as 20 degrees.

ALCO built the Big Boys in Schenectady, New York, and two versions of the engine were made. Starting in 1941, 20 of the 4-8-8-4-1 class engines were made and numbered 4000–4019. In 1944, five of the 4-8-8-4-2 class engines were made and numbered 4020–4024. The difference between the two versions was mainly a different superheater that necessitated changes to the tubing arrangement in the boiler and increased water storage capacity in the tender. These changes were made for maintenance reasons and also due to material shortages during World War II. The first engine, 4000, was delivered to UP in Omaha on 5 September 1941.

The Big Boy’s firebox (left), boiler (middle), and smokebox (right) were all mounted as a single unit and can been seen here, ready to be lowered onto the engine’s frame. The steel that formed the boiler was 1.375 in (35 mm) thick. The two humps above the boiler are the sandboxes. Between the sandboxes is the steam dome, its exposed studs waiting for the cover plate. Exiting the lower part of the smokebox is a duct to feed steam from the superheater to the cylinders. (ALCO image)

All Big Boys were 132 ft 10 in (40.5 m) long and made up of an 85 ft 9.5 in (26.2 m) long engine and a 47 ft .5 in (14.3 m) long tender that carried the locomotive’s coal and water. The locomotive was 16 ft 2.5 in (4.9 m) tall, and its whistle was mounted horizontally so as to not increase the engine’s height. Various ladders and handholds were recessed into the engine and tender to keep the locomotive’s width at a maximum of 11 ft 6 in (3.5 m). The loaded weight of the -1 class was 762,000 lb (345,638 kg) for the engine and 427,500 lb (193,911 kg) for the tender, which gave a total weight of 1,189,500 lb (539,549 kg). The -2 class was heavier at 772,250 lb (350,276 kg) for the engine, 436,500 lb (197,993 kg) for the tender, and a total weight of 1,208,750 lb (548,280 kg). Each set of eight driving wheels supported 540,000 lb (244,940 kg) on the -1 class and 545,200 lb (247,299 kg) on the -2 class. The maximum weight permitted on each of the engine’s 12 axles was 67,800 lb (30,754 kg).

The centipede-style tender was supported by 14 wheels, each 42 in (1.07 m) tall. The first four wheels made up the leading truck, and the 10 trailing wheels were mounted directly to the tender. The tender originally carried 56,000 lb (25,401 kg) of coal in a front compartment. In the late 1940s, 10 in (254 mm) tall steel sideboards were added to the top of the coal compartment. The sideboards enabled an additional 8,000 lb (3,629 kg) of coal to be loaded, increasing the tender’s capacity to 64,000 lb (29,030 kg). A rear compartment held 24,000 gallons (90,850 L) of water for the -1 class and 25,000 gallons (94,635 L) of water for the -2 class. At full steam, a Big Boy engine would consume the tender’s coal and water supply in two hours, but a proper facility could replenish the coal and water in eight minutes.

This image of engine 4023’s tender helps illustrate why the type is known as a centipede tender. Visible on this side are the five wheels mounted to the tender and the two installed in the leading truck. The diagonal row of rivets indicates the partition between the water tank in the rear of the tender and the coal bunker in the front. Note the recessed ladder on the left and the 10 in (254 mm) sideboards atop the tender on the right. (Larry Pieniazek image via Wikimedia Commons)

A large, mechanical stoker auger transported coal from the supply in the tender to the engine’s firebox no regular fireman could keep up with the Big Boy’s prodigious need for fuel. The firebox was 235 in (5.97 m) long and 96 in (2.44 m) wide and burned coal at around 2,000 °F (1,093 °C). Heat from the firebox flowed through the boiler via a series of tubes, each 22 ft (6.7 m) long. The -1 class engine had 259 tubes: 75 2.25 in (57.2 mm) tubes and 184 4.0 in (101.6 mm) flues. With its altered boiler, the -2 class engine had 285 tubes: 212 2.25 in (57.2 mm) tubes and 73 5.5 in (139.7 mm) flues. If laid end-to-end, the tubes and flues would stretch 5,698 feet (1,737 m) for the -1 class and 6,270 feet (1,911 m) for the -2 class. After passing through the tubes, the soot, embers, smoke, and heat from the burning coal flowed into a smokebox at the front of the engine and then out into the atmosphere via dual stacks. Spent steam from the cylinders was directed through the smokebox and helped create the draft that drew air into the firebox, through the tubes, and out the stacks.

The hot tubes, flues, and firebox provided the surface area to turn water in the boiler to steam. The -1 class had 5,889 sq ft (547.1 sq m) of evaporative surface area, and the -2 class had 5,755 sq ft (534.6 sq m). The water in the boiler was heated until 300 psi (20.7 bar) of steam had been generated. With a temperature of over 420 °F (215 °C), the wet, saturated steam was collected in a steam dome positioned above the boiler. The steam flowed from the dome to the saturated steam chamber in the superheater. Small superheater elements (tubes) took the wet steam back into the flues where it was heated well above its saturation value and converted to dry, superheated steam. The superheater elements delivered the dry steam to the superheated steam chamber in the superheater. Combined, the superheater elements stretched for over a mile (1.6 km). The -1 class had a Type E superheater with a surface area of 2,466 sq ft (299.1 sq m). The -2 class had a Type A superheater with a surface area of 2,043 sq ft (189.8 sq m). The Type A required less maintenance than the Type E and provided more than enough steam for the engine, and this is why the older Type A superheater was used. From the superheater, steam was piped to the Big Boy’s two sets of two cylinders.

The smokebox of engine 4014 as it undergoes restoration. The workers inside give some perspective to the immense size of the Big Boy. The large vertical ducts are the engine’s dual stacks. The large pipes behind the stacks and leading down the side of the smokebox take steam from the superheater to the cylinders. The vertical tubes are the superheater elements, and just beyond them are the horizontal tubes and flues that extend through the boiler to the firebox. (Union Pacific image via video screenshot)

The Walschaerts valve gear controlled the flow of steam in and out of the cylinders. A piston spool valve mounted in a valve chest above each cylinder slid back and forth. It directed steam from the center of the valve chest to enter one side of the double-acting cylinder while simultaneously opening the other side of the cylinder, expelling the previous steam charge. The steam flowed into the front of the cylinder and filled its 14,176 cu in (232 L) volume, pushing the 23.75 in (603.3 mm) diameter piston back 32 in (812.8 mm) to the rear end of the cylinder. The steam-distribution valve then slid rearward to open the front part of the cylinder, exhausting the spent steam to the smokebox. Simultaneously, fresh steam was directed into the rear part of the cylinder, pushing the piston back to its original position. Although the cylinder was uniform in size, the cylinder’s return volume was only 13,345 cu in (219 L) on account of the 5.75 in (146 mm) diameter, hollow piston rod taking up some room. The piston rod was attached to the connecting rod via a crosshead. The connecting rod extended back to the third driving wheel in the four-wheel set. Here, the connecting rod was attached to the coupling rod, which was connected to all four driving wheels. To aid traction, sand could be deposited on the rails in front of each drive wheel. The Big Boy had two sandboxes mounted on top of the boiler and each held 4,000 lb (1,814 kg) of sand.

The Big Boy was designed for a top speed of 80 mph (129 km/h), but its highest speed reported was a test at 72 mph (116 km/h). It is unlikely the engine was ever operated in service much beyond 50 mph (80 km/h). Of course, hauling the heaviest loads up the steepest grades reduced the engine’s speed to around 12 mph (19 km/h), the speed at which its tractive effort was at a maximum of some 135,375 lbf (602.2 kN). The 80 mph (129 km/h) speed design ensured that parts were built to withstand stresses well beyond what was needed to haul freight at 40 mph (64 km/h).

The front drive wheels on engine 4017. The black box on the right is the cylinder, with the piston rod extending out to the left. A crosshead joins the piston rod with the connecting rod. The connecting rod extends back and attaches to the third drive wheel, and a coupling rod connects all the drive wheels together. (National Railroad Museum image)

At 41 mph (66 km/h), the Big Boy produced some 6,290 hp (4,690 kW) at the drawbar, which would be around 7,157 hp (5,337 kW) produced at the cylinders. Without any slip, each rotation of the drive wheels moved the engine 17.8 ft (5.4 m). At 41 mph (66 km/h), each drive wheel rotated 202 times a minute, and each double-acting piston made 404 strokes. This resulted in roughly 12,869 cu ft (364.4 cu m) of steam passing through the Big Boy’s cylinders every minute.

Four seats were provided in the Big Boy’s cab, although the engine only required a crew of three: an Engineer, a Fireman, and a Brakeman. If needed, the cab could accommodate six occupants with two additional makeshift seats. Each of the 20 -1 class engines cost $265,174 in 1941, and each of the five -2 class engines cost $319,600 in 1944. The equivalent cost for each engine would be over $4,335,000 in 2016.

Smoke and steam billow out of Big Boy engine 4017 as it starts off from Rawlins, Wyoming. Even though it is a -1 class, the cooler has been removed from the railing on the front of the engine. (Stan Kistler image)

On engine 4000’s first test run east from Ogden, a train of 3,500 tons (3,175 t) was coupled to the locomotive. This was just below the Big Boy’s rating of 3,600 tons (3,266 t). Although the trip over the Wasatch Range was considered a success, the engine performed slightly below expectations. A quick recheck of the manifest revealed that engine 4000 had actually pulled 3,800 tons (3,447 t)—200 tons (181 t) over its rating. With the true weight realized, the Big Boy’s performance was deemed an unequivocal success.

All Big Boy locomotives were pressed into service as soon as they could be delivered. Originally cleared to pull 3,200 tons (2,903 t) up the 1.14% grade between Ogden and Green River, the engines were eventually allowed to haul 4,450 tons (4,037 t) as experience was gained. On a .82% grade, the engines were cleared to haul 5,360 tons (4,863 t). Theoretically, the Big Boy could pull a train 5.5 miles (8.9 km) long on flat ground from a standing start. In practice, the engine routinely pulled over 100 cars.

During World War II, the Big Boys spent most of their time moving freight between Ogden and Green River. On a typical run from Oden to Evanston, Wyoming, with a stop in Echo, Utah, a Big Boy would take about four hours to cover the 76-mile (122-km), uphill route and climb some 2,500 ft (762 m). Engine 4016 made the trip in 3 hours and 50 minutes while hauling 71 cars, for a weight of 3,883 tons (3,523 t). The Big Boy consumed 74,700 lb (33,883 kg) of coal and 34,800 gallons (131,732 L) of water. This averages to 19,487 lb (8,839 kg) of coal and 9,078 gallons (34,364 L) of water used per hour, or 996 lb of coal and 464 gallons of water per mile (280 kg and 1,089 L per km). Under full steam, the Big Boy was said to consume 22,000 lb (9,979 kg) of coal and 12,000 gallons (45,425 L) of water per hour.

To expedite service, especially with heavy trains, even the Big Boy used helper engines or was doubleheaded. Here, engines 4013 and 4004 team up to doublehead a train over Sherman Hill on the way from Laramie to Cheyenne in August 1958. (Otto Perry image via Denver Public Library)

After World War II, Big Boys were occasionally used for trips to southern Utah and did make regular trips into Wyoming, going as far as Cheyenne, 483 miles (777 km) from Ogden. The Cheyenne trips required conquering the 1.55% grade up Sherman Hill and passing through the Hermosa Tunnel at around 8,000 ft (2,438 m). In the 1950s, their service expanded on occasion as far east as North Platte, Nebraska and as far south as Denver, Colorado. Although the engines were cleared for other routes, like Ogden to Los Angles, they never made the journey in regular service. The ever-increasing tonnage needing to move on the rails resulted in even the Big Boys using helper engines to speed up travel over the steep mountain passes. Rarely, two Big Boy engines would be linked to doublehead a train quickly over the mountain.

The Big Boy engines proved very reliable in service, but they did require a significant amount of maintenance. UP considered purchasing additional engines, and other railroads thought about buying Big Boys, but resources were somewhat limited during World War II. After the war, diesel locomotives were proving themselves as the prime mover of the future. Still, Big Boys soldiered on and were one of the last steam locomotives in regular service.

Well-worn engine 4021 hauls freight through Wyoming in June 1956. The Big Boys were one of the last steam engines in regular service. (Chris Zygmunt Collection image)

The last Big Boy was removed from revenue service on 2 July 1959. The engines were kept in storage until August 1961, when the first were retired. The last Big Boy was retired in July 1962. At the time of their retirement, each of the -1 class Big Boys had accumulated over 1,000,000 miles (1,610,000 km)—the equivalent of traveling from the Earth to the Moon and back twice. Engine 4006 had the most miles, at 1,064,625 (1,713,348 km). Each of the -2 class engines had traveled over 800,000 miles (1,290,000 km)—the equivalent of circling the Earth 32 times. At 855,163 miles (1,376,252 km), engine 4021 had the highest mileage of the -2 class. All total, the Big Boys accumulated 25,008,054 miles (40,246,574 km) this is about the distance from Earth to Venus when the planets are at their closest point.

Although the Big Boy was very impressive, there were other locomotives that were larger, heavier, and more powerful, but probably none that were all three. What makes the Big Boy unique is that even with its massive size and colossal power, it was in regular service for nearly 20 years—it was not an experimental train, and it was not limited to a small section of track. The Big Boy was also not a Mallet-type locomotive. Although it was articulated, the Big Boy was not a compound steam engine, which is the second hallmark of a true Mallet.

Seventeen of the Big Boy engines were scrapped, while the remaining eight were put on display in various museums. As of 2016, seven of the Big Boys are still on display. The remaining engine, 4014, was reacquired by UP in 2013 and underwent a five-year restoration at their facility in Cheyenne, Wyoming. The restoration included converting the engine from coal fired to oil fired and was completed in time for the 150th anniversary celebration of the completion of the transcontinental railroad in Ogden, Utah. In May 2019, Big Boy 4014 once again took to the rails—a living tribute to ALCO, UP, the era of steam, and all the men and women who made it possible. 4014 will be used for special excursion service its days as a workhorse ended some 50 years ago.

Big Boy 4014 sits in Cheyenne undergoing restoration. The cab has been removed, and the locomotive has been stripped down to the boiler. (Union Pacific image)

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