|Engines||4*450hp Bristol Jupiter VI|
|Wing Load (kg/m2)||83.5|
|Power load (kg/hp)||7.0|
|Speed at 0m||180km/h|
In Spring 1931 almost whole TsKB personal was involved in design and construction of new heavy bomber. Shoulder-wing monoplane with fixed landing gear had internal bomb bay, quite a novelty at the time, as well as enclosed pilot's cabin and nose enclosed 'barbette', covering 220° in azimuth. D.P.Grigorovich took a risk to rely on projected FED engines (24-cyl 4-row X-type) by A.A.Bessonov. Engines 'podded' installation under the wing does not look optimal, but engine nacells included wing and landing gear struts, keeping the wing clean at the same time.
Nonetheless, TB-5 even on design stage trailed behind the TB-3, which also was under construction at the time. But unlike the all-metal Tupolev's bomber, project of D.P.Grigorovich was of mixed construction. Metal frame (steel and aluminum) was covered with fabric. Substantial savings of aluminum (supply was short in the USSR) could help to beat more advanced competitor.
First blow was received already on the assembly stage: FED engines did not materialize. Each of two was replaced by tandem pair of Bristol Jupiter VI radials. Despite total power was close to projected, drag was increased and propeller efficiency suffered (common for tandem installations).
TB-5 rolled out on 1 May 1931. Very first flights (pilot B.L.Bukhgolts) revealed sluggish performance. Long takeoff, poor climb and speed not reaching even 180km/h. Trials and modifications continued at low pace. In the in the end of year TB-3 rolled out, and interest in TB-5 started to fade. Nonetheless, flights continued.
In Spring 1932 flight of M.M.Gromov fell short from fatal. Rear port engine cradle broke, and running engine turned hanging on wires and pipes. Fire started almost instantly. Engineer A.V.Chesalov bailed out with parachute from tail cabin. M.M.Gromov saw that most of 12 specialists on board have no parachutes (safety!!). He succeeded to blow off the fire by steep diving and landed safely.
Aircraft was abandoned. Whole layout was considered obsolete, and none constructive improvement could save it in 1932. Some elements of the TB-5 construction were used by I.V.Chetverikov for his (also failed) MDR-3.
|Created January 25, 1996
Modified June 1, 1999
by Alexandre Savine;