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Aviation History
1985
1985 - 0746.PDF
Propeller disconnect by propeller pltcri, controlled by power control circuit via servo and lead-screw Monarch B details Monxon/ott Motorcummt Ailerons \ adjustment 'Requested' motor current maintained Power controller 21b foam core 3-AX» STICK Balsa shear web ^--"Carbon spars Glass epoxy shell PROPELLER SECTION EPPLER193 2-5 in dia '035 in wall aluminium spar V„ in plywood ^i__=_c777;rT_^/_ ^ '007 carbon edge ^strip "'" / '/,in2lbfoam VGIassepoxy 7„ in 11b foam I.e. sheeting over carbon -028 in te. wire MODIFIED USSAMAN 7768 Left Ing Gunter Rochelt, an industrial designer whose aeronautical inclinations lie in aero- modelling and hang gliding, built Musculair in three months. Below Monarch's 700W Geist 60/28 motor drives the propeller through two 12V units via a gearbox drive off the propeller shaft to 55ft. All of the Gossamer aircraft had used Berg plastic chain, and its flexibility permitted Parker to slip the main drive off its sprocket during the charge period. As MIT was also discovering, the lOmin input demanded as much from the pilot as did the flight itself. Typical cadence on the pedals is 90, to obtain 245 r.p.m. on the prop, which is controlled through 10° of pitch. Power switching enables the pilot to draw on the storage after establishing airspeed, and the pitch is regulated to opti mise input from the two power sources. Although MIT overtook the Bat for the first prize, MacCready's team, under Martyn Cowley (expatriate editor of UK magazine Aeromodeller) can at least reflect that they were first to average better than 20 m.p.h. (on July 18, 1984) and managed almost 24 m.p.h. average on December 2, 1984, when Bryan Allen resumed the saddle. £5,000 has been awarded as second prize for the July flight. Monarch Born out of experience with Chrysalis, a biplane design created by a team of MIT undergraduates in 1979 and which made about 350 flights with 45 different pilots, the Monarch epitomises design using standard materials. Unlike the Bat with its composites, the MIT machine had to be fabricated with alloy tube spars and fuselage frame under the constraints of cost and available time. It became a 78-day aeroplane from first parts on May 27, 1983 to August 14 rollout, but the unfortunate initial pilot, Guppy Young- ren, suffered wrong-way rotation at the first attempt. Ten days later, with the nacelle rebuilt and Youngren back at his desk in Lockheed, Rick Sheppe termi nated the next flight "only because the radio fell off and hit him". From these beginnings, Monarch was flying up to 24 m.p.h. over 600m within five more days, and champion cyclist Frank Slaughter was recruited as the power unit. Distracted on an early flight, Frank "lost" the Monarch and once more the aircraft retired for rebuild. MIT was learning that accident damage risk elevates proportionately with speed, but by September 2 the Monarch was airborne again and Frank Scarabino enlisted as the most powerful pilot candidate. His first flight was 1,000m; but fate intervened and a nose-over later that month demanded yet another rebuild. News of the Bionic Bat flight on September 25 deflated all hopes, repairs were cancelled, and Parker MacCready was invited to describe his success to MIT at a seminar. Although the MacCready claim was rejected, MIT still expected their rivals to recapture first prize. They were into a Boston winter, committed to academics, and unable to resume full activity. Three vital changes were made. The fuselage was redesigned to cure the nose-over tendency, and a variable-pitch propeller and an automatic control system to regulate motor current were installed. The new components were road tested secretly at night, and by April 3 1984 Monarch B was ready, now fitted with foam ailerons to replace the less effective warp control. Aware that MacCready was removing his storage system, Scarabino FLIGHT International, 16 March 1985
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