518:
378:; each fitting connected to the fuselage via an inclined steel tube. The shock absorber was made of rubber. A pair of V-shaped steel tubes were present to achieve lateral stability. The two semi-axles slid in openings in the vertical wood struts. The undercarriage had a track of 1.5 m (4.92 ft.). The tail skid consisted of a plate spring suspended in overhang. It had a standardised shape and, despite being designed to be long-lasting, was relatively ease to replace.
472:
494:
163:
677:
28:
232:
maintain level flight at speeds as slow as 90 km (55.94 mi.) per hour; its landing speed is 70 km (43.51 mi.) per hour and it could take off within a distance of roughly 60 m (196.85 ft.). Steering was achieved via a double cable arrangement; the fuselage had inspection windows at various locations to permit the examination of these control cables.
235:
The aircraft had a rectangular fuselage that was entirely covered with plywood, which permitted the omission of brace wires. The structure of fuselage consisted of four longerons, which were composed of wood, that connected to various wood uprights and cross bars. The front of the lower longerons was
194:
Flight testing of these early aircraft revealed some deficiencies in the BH-17, which motivated a prompt redesign of the aircraft in 1924. This redesign led to the aircraft being redesignated as the BH-21. Changes included straightened interplane bracing and allowed for a better field of view for the
231:
The Avia BH-21 was a capable fighter aircraft that possessed favourable performances across multiple categories. It could attain speeds of up to 250 km (155.3 mi.) while hauling a useful load of 310 kg (683.43 lb.) and flying in close proximity to the ground. In horizontal flight, the BH021 could
236:
bent; both the lower and upper longerons formed the supports for the engine bed, which was entirely composed of wood. The pilot's cockpit was located directly behind the cell; it was relatively large and comfortable, featuring an adjustable seat and made provision for a dorsal
423:
There were also two experimental variants: the BH-21J with
Jupiter engine (predecessor of BH-33) and a race plane, the BH-21R, with a boosted HS-8Fb engine (298 kW/400 hp). The latter won several national air race competitions in 1925.
301:
covering. These spars were relatively deep and were reinforced around the attachment points to the fuselage, the cabane struts, and the N-struts. The cross section of the wing spars was reduced in order to fit the rims at the wing tips. The
179:, a conventional biplane designed by Pavel Beneš and Miroslav Hajn during the early 1920s as a response to a Czechoslovak Defense Department requirement for a new fighter aircraft. The BH-17 was one of three
356:. A pump was used to supply fuel from this tank to a gravity tank within the center of the upper wing above the cabane. The tanks were unusually light, being made of aluminium sheets joined together using a
314:. Numerous bars were present within the wings, both between the spars and in parallel to them; the ailerons were attached to one such bar. These ailerons were unbalanced, had a steel tube framework and a
286:
of streamlined steel tubing and two pairs of double cables. The brace wires were attached to the lower part of the fuselage and the upper wing, achieving a favourable distribution of stresses.
263:, which were attached to the lower wing, while the staggering increased the pilot's visibility both forward and upwards. The single-piece upper wing was supported in the middle by a
348:, produced inhouse by Avia, that was located underneath the fuselage; it can be raised and lowered as required. Fuel was stored in a tank located in the bottom of the fuselage; a
240:. Embedded into the rear portion of the fuselage was the horizontal stabilizer, which was held in place by two bolts. It had a wooden frame and was covered by plywood. The
912:
Wauthy, Jean-Luc & de Neve, Florian (June 1995). "Les aéronefs de la Force Aérienne Belge, deuxième partie 1919–1935" [Aircraft of the
Belgian Air Force].
166:
Avia B.21.96, nicknamed "Red devil", which flew
Czechoslovak aerobatic flyer František Malkovský. He died in its cockpit after the crash in Karlovy Vary on 8 June 1930
322:. The leading edge was reinforced by false rib tips. As the plywood covering of the wings possessed sufficient rigidity, the wings lacked any interior bracing wires.
1217:
932:
533:
1207:
363:
process. Sufficient fuel could be carried for up to three hours of typical flying; aggressive use of the throttle shortened this time to two hours.
961:
408:
During its entire service life, the BH-21 never engaged in recorded combat incidence. The type was retired years prior to the outbreak of the
244:
comprised two unbalanced sections with wood frames and fabric covering. The rectangular fuselage terminated in a vertical ridge in place of a
143:
during the early 1920s, which was redesigned in response to feedback from an official evaluation of the aircraft as a fighter. Performing its
394:; this led to one aircraft being built for Belgium by Avia while another thirty-nine were produced under license by the Belgian company
722:
889:
259:
while the span of the upper wing was slightly less than that of the lower wing, an arrangement that increased the efficacy of the
191:
companies. After an extensive review, the BH-17 was selected, after which several aircraft were produced for evaluative purposes.
386:
During 1925, quantity production of the BH-21 commenced, a total of one hundred and thirty-nine aircraft were produced for the
318:
covering; they were actuated via a system of tubular rods and levers. Each rib consisted of a plywood web and two double
517:
954:
506:
345:
148:
79:
211:; the BH-22 was fitted with the less powerful 180 HP version while the BH-21 had the 224 kW (300 hp)
1222:
947:
387:
241:
48:
183:
amongst the five Avia designs submitted to the
Defense Department, along with competing designs from the
353:
279:
256:
147:
in
January 1925, it was put into quantity production later that same year. It was operated by both the
370:
was composed of both wood and metal. The vertical struts, which had a gentle conical shape, comprised
1156:
402:
412:. In spite of this, it served as an important stepping stone to more advanced aircraft, such as the
661:
216:
290:
200:
274:
tubes. The lower wing comprised two sections, each of which were directly attached to the lower
1212:
917:
885:
599:
484:
391:
326:
152:
83:
409:
118:
682:
443:
212:
156:
133:
1171:
1106:
499:
375:
371:
188:
129:
64:
1201:
446:
307:
208:
144:
68:
900:
367:
303:
264:
332:
water-cooled piston engine, which was capable of producing up to 300 HP at 1,BOO
1121:
970:
268:
220:
184:
125:
53:
1166:
1161:
1151:
1146:
1141:
1131:
1126:
1101:
1096:
1091:
1086:
1081:
1076:
1071:
1066:
1056:
1051:
1046:
1041:
1036:
1031:
1026:
928:
710:
705:
700:
695:
672:
602:
450:
413:
329:
311:
204:
176:
162:
140:
921:
155:. As well as being a competent fighter aircraft, it was also an accomplished
1136:
1116:
1111:
1021:
1016:
1011:
1006:
1001:
996:
991:
986:
981:
417:
360:
341:
248:; accordingly, the vertical empennage was restricted to a slightly balanced
237:
1186:
275:
180:
1181:
1176:
477:
337:
298:
260:
196:
128:. First flown in January 1925, it served an important role in securing
121:
27:
357:
349:
319:
315:
249:
207:, was also created. Both versions were powered by a Hispano-Suiza V8
124:
605:
water-cooled piston engine, 224 kW (300 hp) at 1,850rpm
516:
398:
283:
271:
161:
939:
943:
333:
294:
245:
562:
8.90 m (29 ft 2 in) upper wing slightly less
521:
Avia BH-21 3-view drawing from NACA Aircraft
Circular No.22
340:
composed of sheet aluminium. Cooling was accomplished by a
390:. In June 1925, it was successful in trials staged by the
252:, which had a steel-tubing framework covered by fabric.
401:
and five by the Société d'Etudes Général d'Aviation
396:
289:
The wing structure consisted of two box-girder type
884:. Godalming, UK: Salamander Books. pp. 33–35.
638:
600–650 km (370–400 mi, 320–350 nmi)
175:The origins of the BH-21 can be traced back to the
103:
98:
90:
75:
59:
47:
39:
34:
20:
459: : Single-seat clipped-wing racing aircraft.
352:covering was used to protect the tank against
159:, winning several air races in the mid-1920s.
955:
8:
880:Green, William; Swanborough, Gordon (1994).
933:National Advisory Committee for Aeronautics
644:7,000 m (23,000 ft) in 35 minutes
534:National Advisory Committee for Aeronautics
374:with metal fittings at their bases for the
962:
948:
940:
17:
844:
842:
626:250 km/h (160 mph, 130 kn)
336:. This engine was entirely enclosed by a
306:was formed by the forward spar while the
282:on each side of the fuselage by N-shaped
936:, 1 November 1926. NACA-AC-22, 93R18510.
823:
821:
819:
817:
815:
813:
794:
792:
790:
788:
786:
784:
765:
763:
761:
759:
757:
755:
745:
743:
739:
325:Typically, the powerplant was a single
632:90 km/h (56 mph, 49 kn)
436: : Single-seat fighter aircraft.
7:
1218:1920s Czechoslovak fighter aircraft
723:List of interwar military aircraft
556:6.87 m (22 ft 6 in)
14:
568:2.74 m (9 ft 0 in)
449:. Led to the development of the
675:
492:
470:
442: : One BH-21 fitted with a
278:of the fuselage. The wings were
26:
1208:Single-engined tractor aircraft
929:"Avia pursuit airplane B.H. 21"
574:22 m (240 sq ft)
1:
882:The Complete Book of Fighters
586:1,075 kg (2,370 lb)
132:national security during the
664:in the upper front fuselage.
899:Serryer, J. (21 May 1926).
580:765 kg (1,687 lb)
1239:
916:(in French) (305): 28–33.
977:
592:140 kg (310 lb)
507:Czechoslovakian Air Force
149:Czechoslovakian Air Force
80:Czechoslovakian Air Force
25:
901:"L'avion de chasse Avia"
255:The wings were slightly
541:General characteristics
857:Serryer 1926, pp. 2-3.
848:Green 1994, pp. 33–35.
660:2 × 7.7 mm (0.303 in)
522:
388:Czechoslovak Air Force
167:
914:Le Fana de l'Aviation
520:
165:
139:It originated as the
662:Vickers machine guns
447:radial piston engine
866:NACA 1930, pp. 5-7.
807:NACA 1930, pp. 3-4.
778:NACA 1930, pp. 1-2.
690:Related development
529:Les Ailes, May 1925
382:Operational history
217:built under license
35:General information
523:
354:incendiary bullets
168:
1195:
1194:
642:Time to altitude:
600:Hispano-Suiza 8Fb
485:Belgian Air Force
392:Belgian Air Force
327:Hispano-Suiza 8Fb
213:Hispano-Suiza 8fb
203:, designated the
153:Belgian Air Force
111:
110:
84:Belgian Air Force
1230:
964:
957:
950:
941:
925:
908:
895:
867:
864:
858:
855:
849:
846:
837:
836:NACA 1930, p. 5.
834:
828:
827:NACA 1930, p. 4.
825:
808:
805:
799:
798:NACA 1930, p. 2.
796:
779:
776:
770:
769:NACA 1930, p. 3.
767:
750:
749:NACA 1930, p. 1.
747:
685:
680:
679:
678:
652:
619:
543:
498:
496:
495:
476:
474:
473:
410:Second World War
201:training version
30:
18:
1238:
1237:
1233:
1232:
1231:
1229:
1228:
1227:
1198:
1197:
1196:
1191:
973:
968:
911:
898:
892:
879:
876:
871:
870:
865:
861:
856:
852:
847:
840:
835:
831:
826:
811:
806:
802:
797:
782:
777:
773:
768:
753:
748:
741:
736:
731:
683:Aviation portal
681:
676:
674:
671:
653:
648:
615:
539:
515:
493:
491:
471:
469:
466:
444:Bristol Jupiter
430:
384:
376:shock absorbers
229:
173:
134:Interwar period
86:
71:
12:
11:
5:
1236:
1234:
1226:
1225:
1220:
1215:
1210:
1200:
1199:
1193:
1192:
1190:
1189:
1184:
1179:
1174:
1169:
1164:
1159:
1154:
1149:
1144:
1139:
1134:
1129:
1124:
1119:
1114:
1109:
1104:
1099:
1094:
1089:
1084:
1079:
1074:
1069:
1064:
1059:
1054:
1049:
1044:
1039:
1034:
1029:
1024:
1019:
1014:
1009:
1004:
999:
994:
989:
984:
978:
975:
974:
969:
967:
966:
959:
952:
944:
938:
937:
926:
909:
896:
890:
875:
872:
869:
868:
859:
850:
838:
829:
809:
800:
780:
771:
751:
738:
737:
735:
732:
730:
727:
726:
725:
714:
713:
708:
703:
698:
687:
686:
670:
667:
666:
665:
646:
645:
639:
633:
627:
624:Maximum speed:
613:
612:
606:
593:
590:Fuel capacity:
587:
581:
575:
569:
563:
557:
551:
514:
513:Specifications
511:
510:
509:
503:
502:
500:Czechoslovakia
488:
487:
481:
480:
465:
462:
461:
460:
454:
437:
429:
426:
383:
380:
372:laminated wood
228:
225:
199:. A dedicated
172:
169:
109:
108:
105:
101:
100:
96:
95:
92:
88:
87:
82:
77:
73:
72:
63:
61:
57:
56:
51:
45:
44:
41:
37:
36:
32:
31:
23:
22:
13:
10:
9:
6:
4:
3:
2:
1235:
1224:
1223:Avia aircraft
1221:
1219:
1216:
1214:
1211:
1209:
1206:
1205:
1203:
1188:
1185:
1183:
1180:
1178:
1175:
1173:
1170:
1168:
1165:
1163:
1160:
1158:
1155:
1153:
1150:
1148:
1145:
1143:
1140:
1138:
1135:
1133:
1130:
1128:
1125:
1123:
1120:
1118:
1115:
1113:
1110:
1108:
1105:
1103:
1100:
1098:
1095:
1093:
1090:
1088:
1085:
1083:
1080:
1078:
1075:
1073:
1070:
1068:
1065:
1063:
1060:
1058:
1055:
1053:
1050:
1048:
1045:
1043:
1040:
1038:
1035:
1033:
1030:
1028:
1025:
1023:
1020:
1018:
1015:
1013:
1010:
1008:
1005:
1003:
1000:
998:
995:
993:
990:
988:
985:
983:
980:
979:
976:
972:
971:Avia aircraft
965:
960:
958:
953:
951:
946:
945:
942:
935:
934:
930:
927:
923:
919:
915:
910:
906:
902:
897:
893:
891:1-85833-777-1
887:
883:
878:
877:
873:
863:
860:
854:
851:
845:
843:
839:
833:
830:
824:
822:
820:
818:
816:
814:
810:
804:
801:
795:
793:
791:
789:
787:
785:
781:
775:
772:
766:
764:
762:
760:
758:
756:
752:
746:
744:
740:
733:
728:
724:
721:
720:
719:
718:
717:Related lists
712:
709:
707:
704:
702:
699:
697:
694:
693:
692:
691:
684:
673:
668:
663:
659:
656:
655:
654:
651:
643:
640:
637:
634:
631:
628:
625:
622:
621:
620:
618:
610:
607:
604:
601:
597:
594:
591:
588:
585:
584:Gross weight:
582:
579:
578:Empty weight:
576:
573:
570:
567:
564:
561:
558:
555:
552:
549:
546:
545:
544:
542:
537:
536:
535:
530:
527:
519:
512:
508:
505:
504:
501:
490:
489:
486:
483:
482:
479:
468:
467:
463:
458:
455:
452:
448:
445:
441:
438:
435:
432:
431:
427:
425:
421:
419:
415:
411:
406:
404:
400:
397:
393:
389:
381:
379:
377:
373:
369:
368:undercarriage
364:
362:
359:
355:
351:
347:
343:
339:
335:
331:
328:
323:
321:
317:
313:
309:
308:trailing edge
305:
300:
296:
292:
287:
285:
281:
277:
273:
270:
266:
262:
258:
253:
251:
247:
243:
239:
233:
226:
224:
222:
218:
214:
210:
206:
202:
198:
192:
190:
186:
182:
178:
170:
164:
160:
158:
154:
150:
146:
145:maiden flight
142:
137:
135:
131:
127:
123:
120:
116:
106:
102:
97:
93:
89:
85:
81:
78:
76:Primary users
74:
70:
69:Miroslav Hajn
66:
62:
58:
55:
52:
50:
46:
42:
38:
33:
29:
24:
19:
16:
1061:
931:
913:
904:
881:
874:Bibliography
862:
853:
832:
803:
774:
716:
715:
689:
688:
657:
649:
647:
641:
635:
630:Stall speed:
629:
623:
616:
614:
608:
595:
589:
583:
577:
571:
565:
559:
553:
547:
540:
538:
532:
528:
525:
524:
456:
439:
433:
422:
407:
395:
385:
365:
324:
304:leading edge
293:with wooden
288:
254:
234:
230:
215:, which was
193:
174:
138:
130:Czechoslovak
114:
112:
107:January 1925
104:First flight
91:Number built
49:Manufacturer
15:
617:Performance
609:Propellers:
596:Powerplant:
269:streamlined
267:made up of
185:Letov Kbely
171:Development
65:Pavel Beneš
1202:Categories
729:References
572:Wing area:
451:Avia BH-33
312:piano wire
177:Avia BH-17
141:Avia BH-17
115:Avia BH-21
922:0757-4169
905:Les Ailes
734:Ctiations
560:Wingspan:
526:Data from
464:Operators
361:soldering
342:honeycomb
276:longerons
257:staggered
238:parachute
1213:Biplanes
1187:Avia 156
669:See also
650:Armament
611:2-bladed
428:Variants
358:patented
346:radiator
261:ailerons
242:elevator
181:biplanes
151:and the
60:Designer
1182:Avia 57
1177:Avia 51
1172:Avia 14
566:Height:
554:Length:
478:Belgium
420:types.
344:-style
338:cowling
320:flanges
299:plywood
122:biplane
119:fighter
99:History
43:Fighter
920:
907:(205).
888:
636:Range:
497:
475:
457:Bh-21R
440:BH-21J
350:rubber
316:fabric
284:struts
280:braced
265:cabane
250:rudder
227:Design
209:engine
117:was a
1167:S-199
1152:B-534
1147:B-158
1142:B-135
1137:B-234
1132:B-122
1102:BH-33
1097:BH-29
1092:BH-28
1087:BH-27
1082:BH-26
1077:BH-25
1072:BH-23
1067:BH-22
1062:BH-21
1057:BH-20
1052:BH-19
1047:BH-17
1042:BH-16
1037:BH-12
1032:BH-11
1027:BH-10
711:BH-33
706:BH-23
701:BH-22
696:BH-17
658:Guns:
548:Crew:
434:BH-21
414:BH-33
399:SABCA
310:by a
291:spars
272:steel
221:Škoda
205:BH-22
197:pilot
157:racer
21:BH-21
1162:S-99
1157:S-92
1127:B-71
1122:B-39
1117:B-35
1112:B-34
1107:B-33
1022:BH-9
1017:BH-8
1012:BH-7
1007:BH-6
1002:BH-5
997:BH-4
992:BH-3
987:BH-2
982:BH-1
918:ISSN
886:ISBN
598:1 ×
418:B-34
416:and
403:SEGA
366:The
297:and
295:ribs
189:Aero
187:and
126:Avia
113:The
67:and
54:Avia
40:Type
603:V-8
550:One
334:rpm
330:V-8
246:fin
219:by
94:184
1204::
903:.
841:^
812:^
783:^
754:^
742:^
531:,
405:.
223:.
136:.
963:e
956:t
949:v
924:.
894:.
453:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
