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Manned electric flight across the USA Although not well publicised at the time, the first solar powered electric flight across the whole of the USA was accomplished back in 1990. Sponsored by Sanyo and using that company's flexible solar cells, the plane had enough power to take off and climb to considerable heights. By LEO SIMPSON Battery powered electric model aircraft have been around for quite a few years but the difference in technology required for a model and that for manned flight is enormous. Typical electric motor driven model planes are powered by high discharge nickel cadmium batteries with enough capacity to last only a few minutes. In 4 SILICON CHIP that time, such planes can climb to considerable heights and achieve high speeds. But when the batteries run down, the flight must inevitably come to an end. Motors for electric powered models don't last long either. Because they have such a high power input, their brushes and commutators don't last long at all and may have to be renewed completely after just a few flights. Manned flight places much more stringent demands on the technology of batteries and motors. For a start, the motor must not only lift the mass of the plane and its batteries into the air but must also carry the human pilot. The plane The plane is essentially a powered glider with the electric motor and propeller mounted in the tailplane. All the power for the plane came from the solar cells mounted on the wings. The solar cell array was used to charge the battery for a few hours so that the plane could take off and climb as high as necessary to take advantage of CHARGING A MOTOR g QUALITY NO BRAND DISKETTES S2 + DIODE v\ FLEXIBLE SOLAR CELLS At---_HA_LL_E_LE_ME_N_Ts_ _ 8-------, c------,. MOTOR CONTROLLER A t - - - - - - f 9.,___ _ _.......,. Ct-<1-------i~ S3 Fig.1: the electrical system of the Sunseeker solar plane consists of a large array of flexible solar cells charging a 120V 4Ah nicad battery. The motor is a brushless DC type rated at 2.2 kilowatts. thermals. The plane would then soar for long distances while the solar cells continued to charge the battery. During each day's flight, the plane's motor and propeller would only be used as necessary to regain height after soaring for long distances or to increase speed. Solar cells Special flexible amorphous silicon solar cells were made by Sanyo for the record attempt. Called Amorton cells, they have very low weight, making them ideal for the purpose. The entire solar cell array, mounted on the wings and tailplane, has an area of eight square metres and weighs just 1.5kg. The peak power output of the solar array is 300 watts. Amorton solar cell film is only 0.12mm thick and is flexible enough to form a tube only 10mm in diameter. It can be shaped to conform to 3-dimensional surfaces that would not be feasible for conventional flat solar cells. Since it is very light, it yields a power to weight ratio of 200 milliwatts per gram. Other possible applications of Amorton solar cell film are for solar powered dirigibles, cars and boats, solar tents, window shades and roofing materials. The output of the Amorton solar cells is fed via a diode to a specially fabricated nickel cadmium battery with a 4 amp-hour rating at 120 volts . Comparatively little information is available about the control electronics or the motor which is rated at 2.2 kilowatts (3hp). This is referred to as a brushless DC motor by Sanyo engineers but the circuit of Fig.1 reveals it to be a 3-phase induction motor with commutation controlled by Hall Effect sensors. The efficiency of the motor and electronic drive system is quoted as 90%. The battery capacity is sufficient to allow the motor to operate continuously for about 15 minutes. Maximum speed of the plane is quoted at 160km/h and cruising speed is 64km/h. Presumably, both these speeds apply during soaring. Takeoff and climbing speeds would be considerably slower. As the dimensions of the plane . show, it really is a glider, having a wingspan of 17. 5 metres and a length of 7 metres. All up weight, without the pilot, was only 90 kilograms. (It Sunseeker solar plane mockup in Australia A mockup of the Sanyo "Sunseeker" solar powered plane will be on display at the Australian International Air Show and Aerospace Expo to be held at the ASTA, Avalon Airport, near Melbourne, during October 1992. A special building is being constructed at ttie entrance to the Expo to house the "Sunseeker" model. Also on show will be a videotape of the plane's record breaking flight. The Air Show and Aerospace Expo will be held from the 21 st to the 25th October 1992 with three trade days and two public days, and will feature extensive flying and ground displays of all aspects of aviation and aerospace. 5.25" 5.25" 3.5" 3.5" DSDD DSHD DSDD DSHD $4.70 $8.95 $8.50 $16.95 II *************** JAPANESE BRAND - - ~-'v1.., FLOPPY DRIVES 3.5" 1.44M 5.25" 1.2M $99.00 $125.00 :s-"sUPER -~ SPECIAL_~ ~7 ~~ ----------EPROMS RAMS 2716 ............. $9.95 2732A ........... $7.50 27C32 ......... $11.50 2764 ............ . $6.50 27C64 ........... $7.00 27128 ........... $7.50 27C128 ........ . $8.00 27256 ........... $8.50 27C256 ......... $9.00 27512 ......... $12.50 27C512 .. ... .. $13.50 27C1001 ..... $23.50 6116 .... ......... $4.50 6264 .. ,. ......... $9.50 62256 ......... $17.50 628128 ....... $60.00 SERIAL PORT CHIPS 8250 ............. $7.50 82450 ......... $17.50 16C450 ....... $18.00 16C550 ....... $29.50 **** ** *** ** *** * ~~~~ ~ . - · ~ ~ t ¥ )if DYNAMIC RAMS 4164-10 ........... $3.25 41464-08 ......... $2.75 41256-08 ......... $2.75 414256-08 ...... $7.95 411000-08 ....... $7.95 256KSIM,SIP. $23.50 IM,SIM,SIP .... $79.00 4M SIM,SIP. $335.00 REGULATORS 7805T .............. $0.50 7812T .............. $0.50 7815T .............. $0.50 7905T .............. $0.60 7912T .............. $0.60 7915T .............. $0.60 317T.. ... $1.50 337T ................ $2.10 723 ............. ..... $0.80 DIODES IN4148 ............ $0.04 IN914 .............. $0.05 IN4004 ............ $0.08 IN4007 ............ $0.1 O IN5404 ............ $0.20 IN5408 ............ $0.25 BRIDGES W04 ................ $0.50 BR64 ............... $1 50 BR104 ............. $2.50 BR254 ............. $3.50 BR354 ............. $3.95 LEDS 5mm RED ........ $0.15 5mm Green ..... $0.25 5mm Yellow .... $0.25 TRANSISTORS BC547/8/9 ........ $0.15 BC557/8/9 ........ $0.15 8D139 .............. $0.45 8D140 ........ ...... $0.45 TIP31C ............. $0.80 TIP32C ............. $0.80 MJ15003 ......... $6.50 MJ15004 ......... $6.50 MJ2955 ........... $2.50 2N3055 ............ $1.50 LINEAR & SPECIAL FUNCTION 1488 ................ $0.50 1489 ................ $0.50 8250 ................ $7.50 82C450 .......... $17.50 16C450 .......... $18.00 16C550 .......... $29.50 XR2206 ............ $8.50 ICL7106 ......... $14.00 324 .................. $0.75 339 .................. $0.50 358 .................. $0.90 555 .................. $0.45 741 .................. $0.55 FREE PRICE LIST UPON REQUEST · IECS ELECTRONICS & COMPUTER SUPPLIERS 289 LATROBE ST MELBOURNE, VICTORIA 3000 PHONE: (03) 602 3499 FAX: (03) 670 6006 MAIL ORDER HOTLINE: (008) 33 5901 ALL MAJOR CREDIT CARDS WELCOME POSTAGE RATES $1.00-$9.99 ......... $3.00 $10.00-$24.99 ..... $3.50 $25.00·$49.99 ..... $4.50 $50.00-$99.99 .... $5.50 $100.00-$199.00 $6.00 $200.00+ ............. FREE OC'l'OflEB 1992 5 Los Ange San D Fig.2: the route of record breaking solar flight across the USA . .Because the weather was not always sunny, the whole journey took place over 7 weeks and a total of 23 flight days. Total flying time was 121 hours. was designed and built by Eric Raymond of Solar Flight Research Co, USA). Record flight The record breaking solar powered flight was made during the northern summer of 1990 across the United States, from the west to the east It started from Desert Center in California on 16th July and, after flying across 10 states, finally reached its destination at Kitty Hawk in Carolina on 3rd September. During this period, there were some days on which the plane could not fly because of poor weather. Thus, the transcontinental journey took a total of 23 flying days. Total flight time for the 3967km journey was 121 hours. Several new world records were set for solar powered flight: (a) longest flight time without landing - 7 hours 35 minutes. (b) longest flying distance without landing - 394.3 kilometres. (c) maximum altitude of 3963 metres (13,000 feet) The previous world record for solar cell powered flight was attained by an American scientist who travelled 322 kilometres while crossing the Dover Straits in 1981. The Sunseeker solar plane has virtually all its horizontal flight surfaces covered with Amorton amorphous silicon solar cells which give a total peak output of 300 watts. No doubt many more solar powered flights will be made in future. Perhaps there will come a day when solar powered planes become popular pleasure craft. SC Protect your valuable issues Silicon Chip Binders These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers & are made from a distinctive 2-tone green vinyl. They hold up to 14 issues & will look great on your bookshelf. * High quality with heavy board covers * Each binder holds up to 14 issues * 80mm internal width * SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A 11.95 plus $3 p&p each (NZ $6 p&p). Just fill in & mail the order form on page 32; or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. 6 SIL/CO,\ ' Cl-III'