enginehistory.org

[abreton]

Has anybody some details about the ill-fated Wright XR-1670 radial, a two-rows, 14 cylinders version of the Whirlwind built ca. 1935/1936 and that equiped the first Curtiss P36 proto ??

Year, datas and others facts -such as the reasons for its cancellation ?

Thanks

Alain

[gwhite]

Are you referring to the R-1510 a 14 cylnder two row version of the R-760? Wright documents do not list a 1670.

[abreton]

No.

The R-1670 was a scaled-up version of the R-1510, bore growing from 5.00 in to 5.25, with stroke unchanged at 5.50 in.

Some documents presented in the AEHS website mention this engine - we found it in the "CW through 1940" , page 16, or in the general US engine designation. The "Curtiss-Wright engine shipments" sheet indicates that 35 (!) R-1510 and R-1670 were built between 1931 and 1937.

I'm interested in the development of this engine, because in the same periods (1932/1934), the French company Hispano-Suiza, who had bought in the late twenties licenses for the Wright Whirlwind and the Cyclone (called here in France Hispano-Suiza 9V and 9Q), developped two-row versions of these two engines.

The Cyclone-based radial had the same bore, with a slightly shorter stroke (....just as R-2600 !). It was called Hispano 14 Ha - later 14 Aa.

The Whirlwind-based engine had greater bore (as R-1670) but shorter stroke, being in fact an over-square model. It was named Hispano 14 Hb - later 14 Ab - and its development was all but satisfactory . We can rather say it was an entire failure, so it would be interesting to know what happened to this Wright engine, which failed too...

I don't know if theses two-row versions were developped in parallel in France and the USA, or if they were independant studies from the same principle - doubling rows is doubling power.

I would rather think about the second idea, because Hispano gave "engine numbers" (HS 79 and 80) to his 14 Ha and 14 Hb, meaning that his design team had worked on these engines. The Hispano-built Cyclone and Whirlwind had no engine numbers - through they were "Europeanised" with metric threadings.

Regards

Alain

[wlewis]

Some what related H-S used the model (Type 80) 14AB Cylinders on two entirely new engines Types 88 (9 cyl) & Type 93 (7 Cyl.) also so all wasn't lost even if the 2 "new" engines were not production