Bell he­li­copters

The be­gin­nings of Bell He­li­copters

Aviation Classics - - CONTENTS -

Arthur Mid­dle­ton Young was a rare com­bi­na­tion of tal­ents. He was an in­ven­tor and en­gi­neer as well as be­ing a philoso­pher and an au­thor. In­ter­est­ingly, he had ac­quired knowl­edge of math­e­mat­ics and en­gi­neer­ing to fully de­velop his philoso­phies of the na­ture of re­al­ity, a con­cept that had fas­ci­nated him from an early age. He was born on Novem­ber 3, 1905, in Paris, France, the son of Charles Young and El­iza Coxe, his fa­ther be­ing a cel­e­brated Philadel­phia land­scape painter. The fam­ily re­turned to Jenk­in­town in Penn­syl­va­nia in 1906, set­tling in a farm near Radnor where Young at­tended the Haver­ford School. He be­came known as an in­vet­er­ate tin­kerer, al­ways mak­ing or im­prov­ing things. He built a crane out of Mec­cano which would lift his brother, hav­ing also made the elec­tric mo­tor that drove the crane. Young also built many model sail­ing boats, sail­ing them dur­ing fam­ily hol­i­days spent on the Maine coast. He wanted to con­tinue his stud­ies at the Mas­sachusetts In­sti­tute of Tech­nol­ogy, but at­tended Prince­ton Uni­ver­sity in­stead af­ter pres­sure from his fa­ther. Here he be­gan study­ing as­tron­omy, but soon swapped to math­e­mat­ics, com­plet­ing all the avail­able maths cour­ses while still in his ju­nior year. At his re­quest, a new course was set up to teach rel­a­tiv­ity, led by one of the out­stand­ing math­e­ma­ti­cians of the day, Oswald Ve­blen, with Young as the only stu­dent. Grad­u­at­ing in 1927, he de­cided that his fu­ture was in phi­los­o­phy, and wished to es­tab­lish a com­pre­hen­sive the­ory of the uni­verse. He soon aban­doned the tra­di­tional

The Bell Air­craft Cor­po­ra­tion was founded on July 10, 1935. Only six years later Lawrence Bell was to in­vite a young en­gi­neer called Arthur Mid­dle­ton Young to bring his fly­ing mod­els to the plant and demon­strate them. The mod­els were he­li­copters, and a whole new chap­ter of Bell’s his­tor y was about to begin.

struc­ture the­o­ries to con­cen­trate on process, to which end he de­cided to de­velop a new in­ven­tion and test his the­o­ries against the ac­tual process in­volved. Es­sen­tially, he wanted to find a prob­lem against which he could ap­ply his knowl­edge of math­e­mat­ics and physics in or­der to de­velop a bet­ter un­der­stand­ing of how the world worked. In 1928, he vis­ited the Patent Of­fice in Wash­ing­ton DC in or­der to as­cer­tain which of the many in­ven­tions he was in­ter­ested in had met with any suc­cess. His in­ves­ti­ga­tion re­vealed that the he­li­copter had been a sin­gu­lar ex­am­ple of fail­ure up to this point, so he elected to bring the prob­lems of ro­tary winged flight to a suc­cess­ful con­clu­sion.

MODEL BE­GIN­NINGS

Work­ing in a con­verted sta­ble on his par­ent’s farm in Penn­syl­va­nia, Young be­gan build­ing and testing model he­li­copters, the first be­ing rub­ber pow­ered and fly­ing for 10 sec­onds in Fe­bru­ary 1929. He de­vel­oped a sys­tem of ailerons on the ro­tor blades con­trolled by a vane on the hub to con­trol di­rec­tion, some of the elec­tric pow­ered mod­els be­ing re­motely con­trolled through leads from a con­trol box also of his own de­vis­ing. For 13 years Young strug­gled to un­der­stand the in­tri­ca­cies of ro­tary winged flight and all the forces at work on a he­li­copter, learn­ing a great deal about sta­bil­ity and how it could be best achieved. He mar­ried in 1933, and moved to a farm near Paoli in

Penn­syl­va­nia, the barn there be­com­ing Young’s new work­shop. He tried tip pow­ered mod­els, one us­ing a vac­uum cleaner mo­tor that drove tip pro­pel­lers via shafts in the ro­tor blades, the com­plex bear­ings and gears be­ing made by Young him­self. This was scaled up to a 10ft di­am­e­ter ro­tor model pow­ered by a 20hp out­board boat en­gine, but proved overly com­plex and suf­fered re­peated fail­ures so was aban­doned af­ter crash­ing in 1938. Also that year he be­gan at­tend­ing the Ro­tat­ing Wing Air­craft Meet­ings at the Franklin In­sti­tute and gained many new in­sights and ideas from such pi­o­neers as Igor Siko­rsky and Hav­i­land Platt. Such was his un­der­stand­ing of the prob­lems of ro­tary winged flight that he was in­vited to speak on his find­ings at the 1939 meet­ing. Just af­ter this meet­ing came Young’s big­gest break­through in the pur­suit of sta­bil­ity, the ro­tor fly bar, also known as the sta­biliser bar. This is a bar that ro­tates with the main ro­tor and has a small blade or a weight on each end. This serves to cre­ate a sta­ble ro­tat­ing ‘plat­form’ in the cen­tre of the ro­tor sys­tem that can re­duce the ef­fect of ex­ter­nal forces such as wind or in­ter­nal forces such as er­rant or un­in­ten­tional con­trol in­puts. Es­sen­tially, the bar acts as a damper on forces act­ing on the main ro­tor and makes the he­li­copter much eas­ier to fly and con­trol. By 1940, Young had patented a work­ing sys­tem that would pro­vide both the sta­bil­ity and con­trol to de­velop a full size he­li­copter from, and be­gan to seek sup­port from the avi­a­tion in­dus­try in build­ing such a ma­chine. In­ter­est in his de­vel­op­ments was al­most nonex­is­tent un­til a friend of Young’s, Dr John Sharpe, vis­ited the Bell fac­tory. Young was in­vited to demon­strate his mod­els and ex­plain his find­ings and de­vel­op­ments to Larry Bell on Septem­ber 3, 1941. Bell was al­ready aware of he­li­copter de­vel­op­ments in Ger­many and had been fas­ci­nated by the pos­si­bil­i­ties of ro­tary winged flight. He was most im­pressed by Young’s work, and agreed to fund the con­struc­tion of two pro­to­type full size he­li­copters to be known as the Bell Model 30.

THE MODEL 30

Work be­gan al­most im­me­di­ately on the new he­li­copter; Young and his long time as­sis­tant Bart Kel­ley mov­ing to the Bell fa­cil­ity in Buf­falo on Novem­ber 24, 1941. The ro­tary wing team were quickly found their own build­ing, a for­mer Chrysler garage in Gar­denville on the out­skirts of Buf­falo, where Dave For­man, a Bell en­gi­neer, was as­signed to man­age the project for the com­pany. The first he­li­copter de­sign was a very straight­for­ward ma­chine in­tended to prove Young’s the­o­ries in a man car­ry­ing air­craft. Pow­ered by a 165hp Franklin six-cylin­der pis­ton en­gine, the fuse­lage and un­der­car­riage were welded steel and alu­minium tubes to re­duce the weight and keep the struc­ture sim­ple. The en­gine was mounted ver­ti­cally in the fuse­lage be­hind the cock­pit, the ro­tor hub and mast be­ing con­nected di­rectly to the en­gine through a uni­ver­sal joint. Be­low the main two bladed ro­tor was Young’s sta­bil­is­ing bar, the arms of which were at right an­gles to the blades of the main ro­tor. The main blades were rigidly fixed to the cen­tral hub and were made of a com­pos­ite of fir and balsa wood with a steel bil­let in­serted into the lead­ing edge. The twin tail ro­tor blades were also solid wood, all of the blades be­ing care­fully shaped to a sym­met­ri­cal aero­foil sec­tion. The tail ro­tor was mounted on the port side of a tube that ex­tended from the rear of the fuse­lage. The first of the two pro­to­types was rolled out on De­cem­ber 24, 1942, named Genevieve and reg­is­tered NX41867. The fuse­lage was left un­cov­ered for the first teth­ered test flights while pi­lots Arthur Young, Bob Stan­ley and Floyd Carl­son fa­mil­iarised them­selves with the con­trols and the re­ac­tion of the craft to con­trol in­puts. The first teth­ered flight was made by Arthur Young on De­cem­ber 29, dam­age from an ac­ci­dent ground­ing the first Model 30 in early 1943. This was re­paired and on June 26, Floyd Carl­son took the first Bell he­li­copter on its first free flight. Dur­ing the next month, speeds of up to 70mph (113kph) were achieved and the open struc­ture was clad in an alu­minium skin. A three wheeled un­der­car­riage re­placed the sim­ple tube skids and a wind­screen was added to the open cock­pit. While the first pro­to­type was be­gin­ning to make its first demon­stra­tion flights to both mil­i­tary and civil­ian agen­cies, the sec­ond Model 30, NX41868 was com­pleted in Septem­ber 1943. This differed greatly from the first pro­to­type, hav­ing a re­vised un­der­car­riage and a semi­mono­coque con­struc­tion rear fuse­lage to save weight. The sec­ond pro­to­type fea­tured an en­closed cabin with two seats ac­cessed by car type doors on ei­ther side, and was in all re­spects a mod­ern he­li­copter as we know them to­day.

FIRST RES­CUES

The first Model 30 suf­fered a crash in Septem­ber 1943, so the sec­ond pro­to­type took over its demon­stra­tion fly­ing. A num­ber of no­table flights were made, in­clud­ing be­ing flown in­side Buf­falo ar­moury on May 10, 1944. The first pro­to­type was re­paired and re­turned to the test fly­ing pro­gramme which was prov­ing so suc­cess­ful that a third Model 30 was un­der con­struc­tion. While this was be­ing built, Bell he­li­copters flew their first two res­cue mis­sions prov­ing the value of the he­li­copter in the search and res­cue (SAR) role. On Jan­uary 5, 1945, Bell test pi­lot Jack Woolams was res­cued by Floyd Carl­son and Dr Thomas Mar­riott af­ter be­ing forced to bail out of a P-59 Aira­comet. Just over two months later on March 14, Floyd Carl­son res­cued two ice fish­er­men trapped on Lake Erie and achieved a great deal of pub­lic­ity for the project and gain­ing

the Trea­sury Depart­ment’s Sil­ver Medal for Floyd Carl­son. The third Model 30 differed again from the first two. It had a four-wheeled un­der­car­riage and an open frame tail­boom, which light­ened the struc­ture con­sid­er­ably and made the air­craft, NX41869, the best per­former of the trio. How­ever, it re­tained the open cock­pit of the first pro­to­type which made the air­craft un­com­fort­able for pi­lots and pas­sen­gers alike. Young came up with a novel and light­weight idea when he sug­gested that the cock­pit be cov­ered with a large plex­i­glass bub­ble to pro­tect the crew from the ro­tor and slip­stream and also to pro­vide an out­stand­ing view. This sug­ges­tion was to lead di­rectly to the first pro­duc­tion model of Bell he­li­copter, the highly suc­cess­ful and adapt­able Model 47.

CER­TI­FIED SUC­CESS

With the out­right suc­cess of Young’s the­o­ries and the test flight pro­gramme, the team at the Chrysler build­ing in Gar­denville was moved to the Bell fac­tory at Niagara Falls Air­port. Here they be­gan work on a de­vel­oped ver­sion of the third Model 30 pro­to­type, pro­vid­ing more power in the shape of a 175hp Franklin and light­en­ing the air­frame as much as pos­si­ble. The skin on the rear fuse­lage was deleted as un­nec­es­sary, the welded tubes of the struc­ture be­ing left open. The un­der­car­riage was sim­pli­fied to four short legs with a cas­tor­ing wheel on the front legs and a fixed wheel on the rears. A two seat de­sign, it was the first Bell he­li­copter to be fit­ted with dual con­trols for use as a trainer. The first flight took place on the same day the new model was rolled out of the fac­tory, De­cem­ber 8, 1945, and would be fol­lowed by 10 more of the type for demon­stra­tion and test fly­ing. The tech­niques of au­toro­ta­tion to safely land a he­li­copter in the event of an en­gine or other fail­ure had been ex­plored and un­der­stood in the Model 30s test fly­ing pro­gramme. With this abil­ity clearly demon­strated, Bell be­gan the process of achiev­ing type cer­ti­fi­ca­tion for the Model 47 with the Civil Aero­nau­tics Ad­min­is­tra­tion. From this test and eval­u­a­tion process, Bell was to gain two ma­jor firsts, the first com­mer­cial he­li­copter li­cence on March 8, 1946, and the first He­li­copter Type Cer­tifi­cate two months later in May. Sales were slow to begin with, the first civil Bell 47, a B ver­sion with a dif­fer­ent cabin, was sold on De­cem­ber 31, 1946. The civil mar­ket be­gan to pick up, sin­gle air­craft be­ing or­dered by or­gan­i­sa­tions all over the US in­volved in all kinds of in­dus­try, the first ex­am­ples be­ing pur­chased by a crop spray­ing com­pany and a geo­phys­i­cal re­search com­pany. The early demon­stra­tions to the US armed forces and the loan of a Bell 47 to the Army in 1946 fi­nally be­gan to bear fruit when the US Air Force or­dered 28 Bell 47As for eval­u­a­tion. Three of th­ese air­craft were mod­i­fied for cold weather tri­als and sent to Alaska in Jan­uary 1947. Known as YR-13S, later YH-13S, 10 of th­ese he­li­copters were later trans­ferred to the US Navy as HTL-1S for sea tri­als, with two more go­ing to the US Coast Guard for their eval­u­a­tion. In Septem­ber 1947, an Ar­gen­tinean crop spray­ing com­pany or­dered 10 Bell 47s to help fight the an­nual lo­cust pop­u­la­tion ex­plo­sion, which they did suc­cess­fully. Sud­denly, the lit­tle Bell he­li­copter was in de­mand ev­ery­where. Bri­tish Euro­pean Air­ways set up an ex­per­i­men­tal he­li­copter di­vi­sion us­ing the air­craft, and the French Navy con­ducted deck tri­als aboard its ships among many oth­ers. In Oc­to­ber 1947, with this level of suc­cess achieved in not only de­vel­op­ing but in sell­ing the con­cept of the he­li­copter, Arthur Young de­cided he had reached his goal, and left, as­sign­ing all his patents on his in­ven­tions to Bell.

He was to pur­sue a ca­reer de­vel­op­ing his philo­soph­i­cal the­o­ries, par­tic­u­larly process the­ory, and founded the Foun­da­tion for the Study of Con­scious­ness. An as­tound­ing, fo­cused and dis­ci­plined man, Arthur Young can be con­sid­ered the ar­chi­tect of Bell’s ro­tary winged suc­cess.

NEW DI­VI­SION

The civil Bell 47 and mil­i­tary H-13 Sioux were to be a star­tling suc­cess for Bell. Suf­fice to say here that 5600 civil and more than 2400 mil­i­tary ver­sions of the Model 47 were built be­tween 1946 and 1974, be­com­ing the first iconic he­li­copter de­sign. They were to be­come syn­ony­mous with the Korean War in their role of trans­port­ing wounded sol­diers back to the Mo­bile Army Sur­gi­cal Hos­pi­tals or MASH units, over 18,000 wounded sol­diers be­ing car­ried by H-13s of the US Army and UN forces. The late 1950s tele­vi­sion se­ries Whirly­birds and the later film and tele­vi­sion se­ries MASH were to make the Model 47 a house­hold icon, in­stantly recog­nis­able as a mod­ern ex­am­ple of Amer­i­can tech­nol­ogy. The armed forces of 36 na­tions were to use the H-13 or Sioux as it was later named, and the air­craft was also pro­duced un­der li­cence by Agusta in Italy, Kawasaki in Ja­pan and West­land in the UK. The suc­cess of the Model 47 meant that a new di­vi­sion of Bell Air­craft was formed just to pro­duce he­li­copters. It was con­sid­ered that a new fac­tory was re­quired to keep up with the de­mand, so a site was se­lected near Hurst just out­side Fort Worth in Texas in Jan­uary 1951. While this fac­tory was be­ing built, pro­duc­tion con­tin­ued in a leased fac­tory in Sag­i­naw un­til the new plant was ready at the end of the year. By 1956, this new fac­tory and its un­der­tak­ings had be­come so large that on Jan­uary 1, 1957, the di­vi­sion be­came a sep­a­rate com­pany in its own right, the Bell He­li­copter Cor­po­ra­tion. Three more he­li­copter mod­els were pro­duced dur­ing this pe­riod, none of which were to reach the suc­cess of the H-13. The first was the five seat Model 42 util­ity and trans­port he­li­copter of 1946 and the mil­i­tary ver­sion, the Model 48 or H-12, but only three pro­to­types of the for­mer were built and 13 eval­u­a­tion ver­sions of the later. The Model 54 four-seat li­ai­son and util­ity he­li­copter of 1948 was in­tended for the USAF but again, only three pro­to­types were built. More suc­cess­ful was the Bell Model 61 or HSL-1, 53 of which were built for the US Navy in re­sponse to an ur­gent re­quire­ment for an anti-sub­ma­rine he­li­copter. This was the only tan­dem ro­tor he­li­copter de­sign pro­duced by Bell, the twin ro­tors pow­ered by a 2400hp Pratt and Whit­ney R-2800 ra­dial en­gine mounted in the rear fuse­lage. The pro­to­type XHSL-1 first flew on March 4, 1953, but suf­fered from se­vere vi­bra­tion and other tech­ni­cal prob­lems which were to de­lay pro­duc­tion. The fuse­lage was built to ac­com­mo­date two sonar op­er­a­tors and two pi­lots, but it was never re­ally a suc­cess in its in­tended role, a few be­ing used by the US Navy to de­velop tech­niques for aerial mine sweep­ing.

TILT RO­TOR

In 1943, Larry Bell was con­sid­er­ing that at­tach­ing the ver­ti­cal take off abil­i­ties of a he­li­copter to the speed and per­for­mance of a fixed wing air­craft, to make what was then termed a ‘con­verti-plane’, would achieve the best of all pos­si­ble worlds. Arthur Young and Bart Kel­ley had be­gun some pre­lim­i­nary draw­ings and built some fly­ing mod­els, but it wasn’t un­til Au­gust 1950 when the US Army an­nounced a de­sign com­pe­ti­tion for an air­craft that a se­ri­ous de­sign study was be­gun. Mcdon­nell, Siko­rsky and Bell all re­sponded, Bell with the Model 200, also known as the XH-33 and later des­ig­nated the XV-3, de­signed by Bob Lichten and Ken­neth Wer­nicke. A sin­gle 450hp Pratt and Whit­ney R-985 ra­dial en­gine was mounted in a con­ven­tional fuse­lage, driv­ing a pair of three-bladed ro­tors at the tips of the wings via shafts. Th­ese ro­tors could be tilted through just over 90°, pro­vid­ing lift when an­gled ver­ti­cally, then an­gling for­wards to in­crease the speed of the XV-3 to al­low the wings to pro­duce lift, the ro­tors now act­ing as pro­pel­lers, only pro­duc­ing thrust.

Bell won a con­tract to pro­duce two test air­craft based on this de­sign in Oc­to­ber 1953, the first fly­ing on Au­gust 11, 1955 with chief test pi­lot Floyd Carl­son at the con­trols. Sev­eral test flights ended in hard land­ings or crashes due to in­sta­bil­ity in the ro­tors, so the sec­ond air­craft had its three bladed ro­tors re­placed by two bladed units and testing re­sumed in Jan­uary 1958 af­ter con­sid­er­able wind tun­nel ex­am­i­na­tion of the in­sta­bil­ity phe­nom­e­non. On De­cem­ber 18, Bell test pi­lot Bill Quin­lan made the first suc­cess­ful tran­si­tion from ro­tor borne to wing borne flight, an amaz­ing achieve­ment for the tech­nol­ogy of the day. Flight testing by the USAF and NASA con­tin­ued un­til June 14, 1966, with the XV-3 amass­ing 250 flights and 110 ro­tor to wing borne con­ver­sions. The last XV-3 is to­day on dis­play in the Na­tional Mu­seum of the US Air Force, hav­ing been re­stored af­ter suf­fer­ing dam­age in a wind tun­nel test in 1966.

PASS­ING OF A LEG­END

As can be imag­ined, with all of the de­vel­op­ments in ro­tary and fixed wing air­craft, par­tic­u­larly the X-plane se­ries, Larry Bell was an ex­tremely busy man in the late 1940s and early 1950s. He had also be­gun work on a de­sign con­cept for a hy­per­sonic air­craft in 1951 which later gained the back­ing of the US Air Force and was to even­tu­ally emerge as the Dyna-soar pro­gramme, as well as which the com­pany had de­vel­oped the Au­to­matic Car­rier Land­ing Sys­tem (ACLS) for the US Navy which en­tered ser­vice in 1955. The over­work of the pre­war years as he strug­gled to build up his com­pany had taken their toll, and in 1953, af­ter a tour of the Korean War theatre to re­port on the use of the H-13 Sioux in that con­flict, he com­plained of chest pains and was di­ag­nosed with se­vere heart dis­ease. He re­signed as Bell’s gen­eral manager on Oc­to­ber 2, 1954, but con­tin­ued to work hard on var­i­ous projects and as a pro­po­nent of avi­a­tion, or­gan­is­ing talks to var­i­ous in­ter­ested groups. How­ever, on May 24, 1956, Larry Bell suf­fered a se­vere stroke, re­cov­er­ing slowly from the ef­fects and resigning as pres­i­dent of Bell Air­craft in Septem­ber. On Oc­to­ber 10 he suf­fered a heart attack that put him back in hos­pi­tal, where, on Oc­to­ber 20, 1956, Lawrence Dale Bell died. The con­tri­bu­tion that Larry Bell and his com­pany made to the devel­op­ment of avi­a­tion can­not be over­stated. They al­ways led the field, never fol­low­ing the trends in air­craft de­sign. They built the first air­craft to fly su­per­son­i­cally in level flight, the first suc­cess­ful tilt-ro­tor and the world’s first com­mer­cially suc­cess­ful he­li­copter. Th­ese are just a few of the ma­jor mile­stones in Larry Bell’s aerospace le­gacy. There is one sad co­in­ci­dence re­gard­ing his death. On the same day, at the Bell He­li­copter plant at Fort Worth, Bell’s test pi­lot the re­doubtable Floyd Carl­son was mak­ing the maiden flight of the Bell Model 204 or XH-40 as it was ini­tially des­ig­nated. This was the pro­to­type that would be­come the Bell UH-1, the most suc­cess­ful air­craft of its type in terms of sales and the world’s first tur­bine pow­ered he­li­copter, bet­ter known as the im­mor­tal Huey. Larry Bell was never to see it fly nor know of the suc­cess it would be­come, but his ca­reer could have no more fit­ting epi­taph. Words: Tim Call­away

Bell

The first Bell Model 30 with the long four skid un­der­car­riage fit­ted dur­ing early test flights.

Edi­tor’s col­lec­tion

Arthur Mid­dle­ton Young, the ar­chi­tect of Bell’s ro­tary winged suc­cess.

Bell Bell Bell Bell Bell

Arthur Young fly­ing one of his re­motely con­trolled mod­els on his farm. The first two Bell Model 30s in flight to­gether show­ing the dif­fer­ent cock­pit and un­der­car­riage ar­range­ments. A re­mark­able colour pho­to­graph of the sec­ond Bell Model 30 as Arthur Young, out­side the air­craft, talks to Larry Bell in the left hand seat and pi­lot Bob Stan­ley. Arthur Young in the cock­pit of the first Bell Model 30. Note the sta­biliser or fly bar the Young in­vented, im­me­di­ately be­low the main ro­tor. Floyd Carl­son, later Bell’s chief test pi­lot, fly­ing the pro­to­type Bell Model 30 while Arthur Young checks the un­der­car­riage.

Michael Peel Bell Bell Bell

Larry Bell, sec­ond from left, with Arthur Young on his right, demon­strat­ing the Model 30 to the USAAF. The first pro­duc­tion Bell Model 47s were dual con­trol and used by Bell as train­ers.

Bell

Joe Mash­man flies the first Model 47 with mem­bers of the Bell He­li­copter team on the out­side, Arthur young is stand­ing on the far side of the air­craft. A line up of Bell H-13DS at the fac­tory. Large scale pro­duc­tion of the type caused the He­li­copter Di­vi­sion to move to the new plant at Fort Worth. The first Bell Model 30 as it ap­pears to­day in the Steven Ud­var-hazy Cen­tre of the Na­tional Air and Space Mu­seum at Chan­tilly,vir­ginia, just out­side Wash­ing­ton DC.

The sec­ond Bell Model 30 was flown in­side the Buf­falo ar­moury on May 10, 1944.

Bell

The first Model 30 was fit­ted with crop spray­ing equip­ment as an agri­cul­tural demon­stra­tor.

Bell Bell Bell Bell Bell

The Bell Model 47A was given the ini­tial des­ig­na­tion of YR-13, later YH-13, 28 of which were eval­u­ated by the US Air Force. The new Bell He­li­copter Di­vi­sion plant near Hurst, just out­side Fort Worth,texas. The most familiar guise of the Bell 47, an H-13D med­i­cal evac­u­a­tion he­li­copter in the Korean War theatre. The Bell 47B had a com­pletely re­vised cock­pit with car type doors. The Bell 47J or H-13J was the firs­the­li­copter to carry a US pres­i­dent, Pres­i­dent Eisen­hower fly­ingfrom the White House lawn as part of a civil de­fence ex­er­cise in 1957.

Con­stance Red­grave Bell Bell

The Bell 47 was also built un­der li­cence in Italy, Ja­pan and the Uk.this is a West­land built Sioux of the Bri­tish Army Air Corps. The fi­nal model of the Bell 47 fam­ily was the 47K for the US Navy, des­ig­nated HTL-7, 18 of which were built as train­ers, re­des­ig­nated TH-13N in 1962. The Bell Model 47 was re­fined into the 47H, also known as the Bel­lar­ius.

Bell Bell Bell Bell

The five seat Bell Model 42, only three of which were built in 1946. Larry Bell in one of the pas­sen­ger seats of the Model 42 with Floyd Carl­son and Joe Mash­man at the con­trols. The Bell Model 54 four seat li­ai­son and util­ity he­li­copter of 1948 was in­tended for the USAF but again, only three pro­to­types were built. The first Bell Model 48, a mil­i­tary devel­op­ment of the Model 42, was des­ig­nated XR-12 and eval­u­ated by the US Air Force. The devel­op­ment of the Bell Model 48 re­sulted in a very dif­fer­ent shape to the cock­pit and cabin. Des­ig­nated YH-12B, 13 of th­ese util­ity he­li­copters were eval­u­ated by the US Air Force.

Na­tional Ar­chives

Arthur Young was a man of ex­tra­or­di­nary dis­ci­pline. His work on de­vel­op­ing the he­li­copter done, he re­turned to his philo­soph­i­cal the­o­ries.

Bell

Bell

Bell Bell NASA Bell

The Bell Model 61 was pro­duced for the US Navy to fill the anti-sub­ma­rine role, 53 were built des­ig­nated HSL-1. Larry Bell with Charles ‘Chuck’yea­ger af­ter one of his su­per­sonic flights in the Bell X-1a.yea­ger de­scribed Bell as a great sales­man of avi­a­tion. The Bell XV-3 tilt ro­tor demon­stra­tor in its early form with the three bladed main ro­tors. The Bell XV-3 af­ter mod­i­fi­ca­tion to two bladed ro­tors. Lawrence Dale Bell, an avi­a­tion pi­o­neer and vi­sion­ary who had an as­tound­ing im­pact on the his­tory of avi­a­tion.

NASA

On De­cem­ber 18, 1958, Bell test pi­lot Bill Quin­lan made the first suc­cess­ful tran­si­tion from ro­tor borne to wing borne flight in the XV-3. The XV-3 in the NASA wind tun­nel, where a ro­tor fail­ure caused sig­nif­i­cant dam­age to the air­craft in 1966.

The Bell Model 61 was a twin ro­tor he­li­copter, seen here with the blades folded.

Bell

NASA

Bell

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.