Development of balloon-borne reel-down and -up winch system

Adv. S~aoc Ees.

Vol.5, No.l, pp.41-44, ]985 Printed in Great Britain. All rights reserved.

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D E V E L O P M E N T OF B A L L O O N - B O R N E R E E L - D O W N A N D -UP WINCH SYSTEM Y. Matsuzaka, T. Yamagami, M. D. Yamanaka* and J. Nishimura Institute of Space and Astronautical Science, Tokyo 153, Japan

ABSTRACT Balloon-borne winches, which can reel down and up scientific instruments repeatedly, have been developed since 1981 in order to observe stratospheric vertical microstructures. The instrument is suspended by a kevler wire through a traverse-cum ropeguide, and its depth is accurately measured by counting numbers of spool rotations and ropeguide turns. Battery consumption is minimized by utilizing an efficient deccelerator and a hysteresis brake. In 1983 we have successfully performed to reel up and down a 12 kg payload through 1 km for three cycles at 24 km altitude. We are improving the capability of the winch, and have succeeded (May 1984) to reel down a 22 kg payload up to 3 km from a balloon. INTRODUCTION We developed and used several types of balloon-borne winches mainly in order to put a payload apart from a balloon during observation [1][2]. We also succeeded to control balloon altitudes using exhausting valves and ballasts so as to vary or keep the observation levels [3][4]. However, for observations of stratosphere in vertical scales thinner than i00 m, we must develop a balloon-borne winch reeling down and up scientific instruments continuously. 8o we started in 1981 to develop such a reel-down and -up winch system [5]. Similar systems have been also developed by Cadet et al.[6] and by Hazen and Anderson [7] independently. Compared to them, our winch has relatively smaller weight and simpler structure. Simple systems have a great merit to carry out balloon observations where it is very difficult to recover the payload instruments without any damage. In Japan, such a merit is much more important (cf. [3]), since the recovery is normally made on the sea. For the first time we made a winch capable to reel a 6 kg payload through 600 m, which was successfully used for four cycles of turbulence survey at about 24 km altitude in September 1982 [2][5][8]. After that we improved the driving and brake systems to minimize the battery consumption, and have succeeded to reel a payload of 12 kg for I km span for three cycles at similar altitudes [5][9]. Here we shall overview the design and flight results of our balloon-borne winches, mainly of the 1983-type winch, and add a brief report of recent success of 3 km reel-down of a 22 kg payload. Details of our winches were shown in [2][5], and valuable data of stratospheric turbulence were published in [8][9]. DESIGN AND CONSTRUCTION The 1983-type winch has been designed to reel down a payload of about i0 kg continuously through i km in about one hour and to reel up it continuously also in about one hour. The construction and dimension are shown in Fig. 1, and the total weight is i0 kg. The driving part of this winch consists of a DC servomotor (24 V, 60 W; 3000 rpm) and a deccelerator. The deccelerator is a harmonic-gear unit (Harmonic Drive Systems Co., FB-20-80-2) and its gear ratio is 1/80. The mechanical efficiency of this gear unit is very high as 80 %. By application of the harmonic-gear deccelerator, the torque capacity and efficiency have been much improved in comparison with the 1982-type winch [2][5]. The reel of the winch has a stainless-steel spool (i0 cm dia.) and a ropeguide system. For 1 km suspension, a kevler rope (dia.: 1 mm; weight: 0.9 kg/km; breaking strength: 60 kg) is used. The kevler (#29), made in DuPont Co., is a kind of aromatic polyamid flyers. The ends of the rope should be carefully set on the winch spool and on the payload gondola,

~Graduate student of Nagoya University. 41

42

Y. Matsuzaka

et al.

since its breaking strength may be weaken if its ends are injured. When the kevler rope is fully wound up, the spool diameter becomes 14.5 cm, so that the maximum torque for a 12 kg payload suspension becomes about 90 kg-cm. A rotation counter is attached to monitor the reel-down depth. The ropeguide of the winch has a traverse-rum system in order for reeling the wire homogeneously around the spool. The rum right-to-left motion is made to follow the spool r n t ~ i o n , a chain connectin~ between them. A microswitch is attached at an end nf ~he traverse-cum, and signals of the switch is monitored for quick-look of the reeldow, depth. One pulse is produced in every 155 spool rotations. In the 1983-type winch we use two types of brakes replacing the magnetic coupling brake of the 1982-type [2][5]. One is a hysteresis brake (Sinko Electric Machine Co., HB-25), and another is an electromagnetic brake (ibid., ERS-175). The hysteresis brake is used during reeldown. We can control its brake torque by changing the input voltage, which is stepwise controlled by the telecommand (2.5 kg.cm generating at 24 V input). During reel-down we utilize the payload weight itself with applying an appropriate hysteresis-brake torque or, if necessary, operating the driving motor. The electromagnetic brake, generating a torque of i0 kg cm for a 24 V input, is use to hold a payload or for an emergency stop. Fig. 2 shows the motor currents vs. temperature variations measured in the laboratory experiment. The current increase is less than about 1 A even when the winch is cooled from 25"C to -30*C. We also note that fluctuations of the motor current, shown by error bars, do not increase at lower temperatures. A grease, UNI-AF (Nikko Industry Co.), was used for lubrication of the gears and shaft of the motor. This grease can lubricate the gears and motor shaft in the temperature cooler than -60"C.

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FLIGHT PERFORMANCE The 1983-type winch was used for an observation of stratospheric turbulence [9] carried out at Sanriku, .Japan, in 26 September, 1983. The whole balloon system used in this experiment is illustrated in Fig. 3. The payload (the lower gondola) to be reeled down and up by the winch is 50 x 50 x 60 cm 3 in volume and 12.2 kg in weight. The kevler wire is 1013 m in length and 0.9 kg in weight. The payload instrument gondola was settled within a container (the lowest part of the control gondola mounting the winch) until the balloon reached the flight level of about 24 km in altitude. The first reel-down of the payload was started at 0955 .JST as shown in Fig. 4. The winch was stopped from 0938 to 0955 JST to confirm operations of the scJentific instrument and the winch itself. For one reeldown through ] km, it took about 55 min. We carried out ree]ing down/up for three cycles until the balloon cut off at 2214 .]ST over the Pacific Ocean (480 km eastward from Sanriku). Fig. 5 shows a 1 km continuous reelup sequence started at 1830 JST in the second cycle. It took about 65 min for this continuous I km reel-up. We find similar performance during reeling down/up in the other cycles. According to monitored temperatures of the motor sheath and of the electromagnetic-brake case, the temperature increase after a I000 m reel-down is 25-30°C [5], This performance is much better than that of a 300 m reel-down (about 35 ° C) in the 1982 experiment [2]. However, the interior temperature of the motor is considered to be 40-50°C higher than the monitored sheath temperature. Thus we have to improve the heat dissipation characteristics of the motor, if we want to reel up and down more frequently. Fig. 6 shows the spool rotations, motor currents and reeling velocities during a reel-down (upper graph) and a reel-up (lower one). In the reel-down the spool rotation speed is 0.86-0.91 turn/sec, which corresponds to the reeldown velocity of 40-30 cm/sec. The motor

Development of Winch Systems

43

current in the reel-down is 0.6-i A. These are greatly improved from those of the 1982-type (42-14 cm/sec and 9-10 A) [2], as expected in designing the winch. In the reel-up the spool speed is 0.77-0.73 turn/sec, i.e., 24-34 cm/sec in reel-up velocity. The reel-up motor current is 3.5-3.8 A. The battery used in the flight experiment is Pb-type (Nationa] LCRIIOI2;12V x 2; ]OAh x 2 packs = 20 Ah in the normal temperature) [2][5], of which the weight is 4.8 kg. From the motor current measurement the power used in one cycle of reeling down/up is estimated to be 4.8 Ah. Thus the battery capacity of 14.4 Ah may be consumed in the three cycles of reeling down and up. Note that the reel-down power through i km is only 0.7 Ah, which is much better than that through 600 m in the 1982 experiment (5 Ah) [2]. This is a result of utilizing the harmonic-gear deccelerator and the hysteresis brake in the 1983-type winch system. 0

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Table I

Su,Tnary of the reel-up and -down system used in September 1983.

~INCH ~EIGHT

]0 KG

PAYLOAD~EIGHT

12 KG

REELDOWNDEPTH

~013 H

REELDOWNVELOCITY

~0-~0 CI¢/SEC

REELOO.N UP CYCLES3ccLEs REELUP VELOCITY

2q-~q CM/SEC

}I]NCH DECELERATOR

HARMONIC GEARS

~INCH ~RAKES

HYSTERESIS + ELECTRORAONETIC

BATTERY CONSURPTION

ILI,II A'HOUR/~ CYCLES

BALLOONALTITUDE

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F i g . 6 Time v a ~ a t i o n of" ,~;pool o ~ • ; motor current and Zine veZocit7 in a reeZ-up and a reeZ-(fown. FURTHER IMPROVEMENT Based on the success of the 1983 experiment, we have newly made a winch, which h a s essentially the same construction as that of the 1983-type and can reel a payload weight of some tens kilograms for a span of 3 km. The construction of the 1984-type winch is shown in Fig. 7. This winch has been used for a flight to observe stratospheric turbulence in 17 May 1984. The payload weight of the 1984 experiment is 22 kg, and we have succeeded to reel down it up to 3 km from 23 km altitude by a mean velocity of about 20 m/min (see Fig. 8). After reeling back up to 1.7 km by similar reeling velocity, we have noticed from the monitored signals that the wire might be wound inhomogeneously, and have decided to stop the motor. The brake mechanism, motor performance and battery consumption of the 1984-type winch seem all perfect throughout the flight experiment.

Y. Matsuzaka et al.

44

In this experiment we have also succeeded to make a zigzag scan of a thin layer of turbulence. Further analyses of the 1984 flight results are now in progress. We consider that there are no problem to improve the capability up to a span of several kilometers and a payload of several tens kilograms with using the same construction and mechanism as the 1983and 1984-types of winches.

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CONCLUSIONS

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We have develeped a reel-down and -up system for scientific balloon observations. The specifications of the ]983-type w~nch system is summarized in TABLE i, which is quite small and simple constructions. We have perfectly accomplished to reel down/up a 12 kg payload through i kin, and succeeded to reel down a 22 kg payload up to 3 kin, Jn spite of the quite small and simple constructions. Many fruitful results of the stratospheric turbulence have been obtained by using this winch system, which are much recognized Jn activities o{: the Middle Atmosphere Program (MAP). Our future plan J s to develop a win(h, which can smq)end a payload of several tens kilograms and reel up and down it throuzh a distance ~[ ,~+weral kilometers [o~ many cycles. Wc believe that this system would be very useful als(~ f<,t muny other stratospheric studies. ACKNOWLEDGEMENTS We t h a n k P r o f e s s o r II, H i r o s a w a f o r h i s v a l u a b l e advlces, and many c o l l e a g u e s for their helpful cooperations. The b a l l o o n o b s e r v a t i o n o f s t r a t o s p h e r i c t u r b u l e n c e was p r o p o s e d by Professor I{. Tanaka of Nagoya [!niversity as an i Lem of ,Japanese MAP project. REFERENCES I. S.Ohta, H.AkJyama and Y.Otsuka, Instrument for the extention of the suspention rope of the balloon gondola, Bull.lnst.Spac.Aeron. Sci.Univ. Tokyo, 9, 216-222,in .Japanese (]973) 2. Y.Matsuzaka, Y.Koma, T.Yamagami and J.Nishimura, Balloon-borne winches for reeling down payload instruments, Bul].Inst.Spac.Astron. Sci.,Spec. Issue, 8, 33-49, in Japanese (]983) 3. J.Nish:imura and ll.Hirosawa, Systems for long duration flights, Adv.Space Res., I, #Ii, 239-249 (1981) 4. M.Fujii, Y.Koma, Y.Okabe, S.Ohta, J.NJshimura and H.Hirosawa, Automatic control of balloon altitude, Proc.ISTS, 13, ]183-1187 (]982) 5. Y.Matsuzaka, T.Yamagami, J.Nishimura and M.D.Yamanaka, Reel-up and -down system for balloon-borne instruments, Proc. ISTS, 14, in press (1984) 6. D.Cadet, G.Bannerot and B.Brioit, A new two-dimensional sounding technique from a balloon: Application to the study of a stratospheric shallow layer, (1977) 7. N.L.Hazen, and J.G.Anderson, Reel down: A balloon-borne winch system for stratospheric sounding from above, AIRR-84-O027, 9pp (1984) 8. M.D.Yamanaka, and H.Tanaka, Meso- and microscale structures of stratospheric winds: A quick-look of balloon observation, ,l.Meteor. Soc.Japan, 62, 177-182 (1984) 9. M.D.Yamanaka, H.Tanaka, H.liirosawa, Y.Matsuzaka, T.Yamagami and J.Nishimura, "Measurement of stratospheric turbulence by balloon-borne "glow-discharge" anemometer, J.Meteor.Sc~c. Japan, to appear (]984)