289:
displacement modes were observed at 90 km/h (55.9 mph; 48.6 kn). The fundamental mode was seen, at a frequency of 3.3 Hz but at 140 km/h (87.0 mph; 75.6 kn) the wing oscillated at 5.8 Hz in a second harmonic mode. During these largely vertical excursions, the wing also twisted and its overall motion excited vibrations in the rear fuselage and tail unit. The flutter problems were addressed by
266:
The SB-8 V2 had shown that glass-fibre wings could be made stiff enough to avoid aeroelastic flutter problems and that the higher aspect ratio produced the expected improvement in glide angle. It was natural for the next
Akaflieg Braunschweig design to have a wing of greater span, replacing the wing
284:
Both SB-8s competed at the German
National Championships of 1968, Wolfgang Beduhn finishing fifth in the V1 and Helmut Treiber seventh in the V2. The V2 went on to become the SB-9, but the V1 remained in regular use at Brunswick until 1989. It remained airworthy after that, though flown less often,
271:
flew only three days later. The increase in aspect ratio over the SB-8 increased the measured best glide ratio from 40:1 to 46:1 and decreased the measured minimum sink rate from 0.61 m/s (120.08 ft/min) to 0.51 m/s (100.39 ft/min). The new wing took advantage of the flexibility
332:
The SB-8V2 was modified with a four-part wing of 22 m (72 ft 2 in) span, fitted with elastic flaps. SB-9 Stratus was first flown in
January 1969. It is Empty weight, 325 kg (717 lb), maximum in flight weight, ballasted, 421 kg (928 lb). Flutter problems were
288:
The SB-9 was used by the
Akaflieg students in competitions between 1969 and 1971. It also gave them the opportunity to film and study the alarming motions of the wing when fluttering, recording their observations on film in slow motion and in the air. Two antisymmetric, odd, sine-like lateral
257:
also limited its smooth air cross country speed as there was no provision for ballast. Later, removable steel tubes filled with lead pellets were added to the wing roots of the SB-8 V1 to increase wing loading. A second aircraft, SB-8 V2, was therefore built with a stiffened, heavier wing and
147:) is one of fourteen German undergraduate student flying groups sponsored by their home technical university. Several have designed and built aircraft, often technically advanced and leading the development of gliders in particular. The Brunswick students had been exploring the use of
272:
of glass fibre to implement elastic flaps. The intention was to avoid the interruption to the wing profile at the hinge, particularly on the critical upper surface, and leakage through it by bending the upper surface instead. This method had been used earlier in the wooden-winged
267:
of the SB-8 V2 airframe with a four-panel wing of similar construction but 22 m (72 ft 2 in) span. At the time of its first flight in
January 1969 the SB-9 had probably the greatest span of any glider then flying, though the 22 m (72 ft 2 in)-span
300:
The career of the SB-9 ended in 1972, when it was decided to use its wing on the SB-10 two-seater, a new design with a very different fuselage and the span increased still further with an 8.7 m (28t ft 7 in) centre section.
175:, which also had an aspect ratio of 23. It performed well but had difficult handling characteristics, attributed to its Eppler aerofoil section. The SB-8 has an 18 m (59 ft 1 in) wingspan, a two-piece wing of
320:
Original aircraft, empty weight of 260 kg (570 lb) and a maximum take-off weight of 365 kg (805 lb). Flutter restricted maximum permitted speed to 170 km/h (110 mph; 92 kn).
906:
258:
provision for water ballast, which addressed both aero-elasticity and wing loading problems, allowing the glider to fly safely, without flutter, at 200 km/h (124.3 mph; 108.0 kn).
183:, a slightly tapered center section, and more strongly tapered outer sections. It is built around a box beam, with balsa ribs and a torsion shell of glass fibre laid over balsa. The wing is
982:
249:
The first flight was made from
Brunswick airport on 25 April 1967; testing confirmed that the glass fibre structure was too flexible and at high speeds the SB-8 exhibited
916:
911:
901:
152:
326:
Stiffened wing, weights increased by 40 kg (88 lb). Provision for water ballast, maximum permitted speed increased to 200 km/h (120 mph; 110 kn)
877:
886:
140:
592:
0.51 m/s (100 ft/min) at 80 km/h (50 mph; 43 kn) at 27.3 kg/m (5.6 lb/sq ft) and 414 kg (913 lb)
577:
0.61 m/s (120 ft/min) at 88 km/h (55 mph; 48 kn) at 27.7 kg/m (5.7 lb/sq ft) and 385 kg (849 lb)
176:
870:
1008:
1013:
863:
1018:
946:
822:
156:
91:
159:, wingspan and aspect ratio were progressively increased. The aspect ratio was increased from 23 to 36.6, resulting in
214:
The fuselage of the SB-8 is built with a fibreglass skin, over a balsa shell, with balsa vertical frames and two pine
961:
931:
926:
921:
797:
683:
218:
main formers in the region between the wings. The nose is pointed and slightly drooped, with a short, single piece,
172:
79:
1003:
723:
1023:
966:
956:
951:
426:
333:
tackled with a span reduction to 21 m (68 ft 11 in) and mass-balancing the ailerons.
239:
148:
253:, limiting its maximum permitted speed to 170 km/h (105.6 mph; 91.8 kn). The low
104:
31:
781:
667:
268:
192:
8:
789:
231:
188:
124:
675:
250:
160:
108:
34:
759:
385:
22 m (72 ft 2 in) (reduced to 21 m (68 ft 11 in) later)
290:
818:
793:
719:
679:
219:
243:
196:
855:
204:
123:
wood structure. Two were built; the second of which was later fitted with a high
788:(2nd revised ed.). Königswinter: EQIP Werbung & Verlag GmbH. pp.
782:
674:(2nd revised ed.). Königswinter: EQIP Werbung & Verlag GmbH. pp.
668:
838:
997:
222:
just ahead of the wings, tapering gently aft to a straight tapered balsa/GRP
184:
463:
root:Wortmann FX 62-K-153, mid:Wortmann FX 62-K-131, tip:Wortmann FX 60-126
254:
180:
49:
116:
538:
207:
on the inboard wing panel and ailerons which are coupled to the flaps (
227:
208:
200:
242:. On the ground the SB-8 is supported by a retractable, unsprang
458:
294:
215:
112:
297:, and by a span reduction to 21 m (68 ft 11 in).
235:
223:
621:
maximum wing loading 27.3 kg/m (5.6 lb/sq ft)
285:
and was still on the German Civil
Aircraft register in 2010.
273:
120:
748:. London: Sampson Low, Marston & Co. Ltd. p. 390.
337:
143:
151:in a series of related gliders, beginning with the
885:
203:on the outer panels. Both SB-8 built have camber
995:
549:41.6 at 85 km/h (53 mph; 46 kn)
563:46 at 83 km/h; 52 mph (45 kn)
871:
718:. Stuttgart: Motorbuch Verlag. p. 119.
661:
659:
657:
655:
653:
651:
649:
647:
645:
643:
641:
878:
864:
812:
709:
707:
705:
703:
701:
699:
697:
695:
543:200 km/h (120 mph, 110 kn)
134:
739:
737:
735:
713:
638:
606:28.6 kg/m (5.9 lb/sq ft)
773:
746:Jane's All the World's Aircraft 1966-67
692:
115:in the 1960s, constructed largely from
996:
831:
779:
743:
665:
279:
859:
732:
92:Akaflieg Braunschweig SB-10 Schirokko
806:
752:
414:15.48 m (166.6 sq ft)
230:carries a conventional single-piece
199:midway along the center section and
364:7.505 m (24 ft 7 in)
338:Specifications (SB-8 V2 & SB-9)
145:The Brunswick Academic Flying Group
13:
1009:1960s German experimental aircraft
399:14.1 m (152 sq ft)
129:Akaflieg Braunschweig SB-9 Stratus
14:
1035:
370:18 m (59 ft 1 in)
80:Akaflieg Braunschweig SB-7 Nimbus
817:. Air Britain (Historians) Ltd.
815:European registers handbook 2010
107:, single-seat, high performance
261:
16:German single-seat glider, 1967
1014:Akaflieg Braunschweig aircraft
716:Die berümtesten Segelflugzeuge
1:
631:
246:, assisted by a tail bumper.
1019:Aircraft first flown in 1967
7:
304:
171:The SB-8 is similar to the
10:
1040:
504:451 kg (994 lb)
469:301 kg (664 lb)
211:) on the outboard panels.
127:(30:1) wing, becoming the
101:Akaflieg Braunschweig SB-8
975:
894:
813:Partington, Dave (2010).
744:Taylor, John W R (1966).
519:421 kg (928 lb)
498:403 kg (888 lb)
484:325 kg (717 lb)
144:
21:
714:Brütting, Georg (1973).
179:profile with an unswept
1004:1960s German sailplanes
780:Simons, Martin (2006).
666:Simons, Martin (2005).
349:General characteristics
244:monowheel undercarriage
166:
155:. From the SB-8 to the
1024:Shoulder-wing aircraft
135:Design and development
887:Akaflieg Braunschweig
839:"Flutter on the SB-8"
191:, with Schempp-Hirth
141:Akaflieg Braunschweig
784:Sailplanes 1945-1965
670:Sailplanes 1965-2000
547:Maximum glide ratio:
311:Sailplanes 1965-2000
502:Max takeoff weight:
280:Operational history
119:skin over built up
539:Never exceed speed
269:Holighaus Nimbus 1
991:
990:
907:SB-02 Brockenhexe
824:978-0-85130-425-0
313:unless excepted.
97:
96:
1031:
880:
873:
866:
857:
856:
850:
849:
847:
845:
835:
829:
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804:
803:
787:
777:
771:
770:
768:
766:
756:
750:
749:
741:
730:
729:
711:
690:
689:
673:
663:
533:
351:
276:glider of 1953.
185:shoulder mounted
146:
88:
76:
66:
46:
38:Type of aircraft
19:
18:
1039:
1038:
1034:
1033:
1032:
1030:
1029:
1028:
994:
993:
992:
987:
971:
947:SB-10 Schirokko
890:
884:
854:
853:
843:
841:
837:
836:
832:
825:
811:
807:
800:
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347:
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307:
282:
264:
169:
137:
86:
74:
64:
45:National origin
44:
39:
17:
12:
11:
5:
1037:
1027:
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989:
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929:
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868:
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751:
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724:
691:
684:
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365:
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318:
306:
303:
291:mass-balancing
281:
278:
263:
260:
240:fabric covered
177:Wortmann FX 62
168:
165:
136:
133:
95:
94:
89:
87:Developed into
83:
82:
77:
75:Developed from
71:
70:
67:
61:
60:
57:
53:
52:
47:
41:
40:
37:
28:
24:
23:
15:
9:
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4:
3:
2:
1036:
1025:
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1001:
999:
984:
981:
980:
978:
974:
968:
965:
963:
960:
958:
955:
953:
952:SB-11 Antares
950:
948:
945:
943:
940:
938:
935:
933:
930:
928:
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923:
920:
918:
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799:3 9807977 4 0
795:
791:
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736:
727:
721:
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710:
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685:3 9808838 1 7
681:
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605:
604:Wing loading:
602:
601:
591:
588:
587:
586:
585:
584:
583:
582:
581:
576:
575:Rate of sink:
573:
572:
562:
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558:
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545:
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540:
536:
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514:
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512:
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497:
496:Gross weight:
494:
493:
483:
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468:
467:Empty weight:
465:
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130:
126:
122:
118:
114:
110:
106:
102:
93:
90:
85:
84:
81:
78:
73:
72:
68:
63:
62:
58:
56:First flight
55:
54:
51:
48:
43:
42:
36:
33:
29:
26:
25:
20:
942:SB-9 Stratus
941:
936:
842:. Retrieved
833:
814:
808:
783:
775:
763:. Retrieved
754:
745:
725:3 87943171 X
715:
669:
618:
603:
589:
574:
560:
546:
537:
530:
528:
516:
501:
495:
481:
466:
457:
443:
427:Aspect ratio
425:
411:
396:
382:
367:
361:
355:
348:
346:
342:
341:
329:SB-9 Stratus
310:
308:
299:
287:
283:
265:
262:SB-9 Stratus
255:wing loading
251:wing flutter
248:
213:
181:leading edge
170:
138:
128:
125:aspect ratio
105:experimental
100:
98:
65:Number built
50:West Germany
32:experimental
30:Single seat
962:SB-13 Arcus
932:SB-7 Nimbus
927:SB-6 Nixope
922:SB-5 Danzig
531:Performance
226:unit. The
161:aeroelastic
117:glass fibre
998:Categories
632:References
397:Wing area:
309:Data from
163:problems.
368:Wingspan:
343:Data from
228:tailplane
209:flaperons
193:airbrakes
111:built in
976:Projects
889:aircraft
305:Variants
295:ailerons
234:and the
232:elevator
201:ailerons
189:dihedral
187:at 1.5°
895:Gliders
844:19 July
765:19 July
459:Airfoil
362:Length:
323:SB-8 V2
317:SB-8 V1
216:plywood
195:at mid-
113:Germany
821:
796:
760:"SB-8"
722:
682:
293:, the
236:rudder
224:T-tail
220:canopy
109:glider
103:is an
35:glider
983:SB-15
967:SB-14
957:SB-12
619:SB-9:
590:SB-9:
561:SB-9:
517:SB-9:
482:SB-9:
444:SB-9:
412:SB-9:
383:SB-9:
356:Crew:
274:HKS-1
205:flaps
197:chord
157:SB-10
121:balsa
59:1967
27:Role
22:SB-8
937:SB-8
917:SB-4
912:SB-3
902:SB-1
846:2012
819:ISBN
794:ISBN
792:–7.
767:2012
720:ISBN
680:ISBN
678:–5.
446:31.3
173:SB-7
167:SB-8
153:SB-6
139:The
99:The
790:154
238:is
149:GRP
1000::
734:^
694:^
676:41
640:^
431:23
131:.
69:2
879:e
872:t
865:v
848:.
827:.
802:.
769:.
728:.
688:.
541::
461::
429::
358:1
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