From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparative analysis table of American car heaters.
| Identifier | ExFiles\Box 137\1\ scan0200 | |
| Date | 7th December 1936 | |
| 7th December, 1936. COMPARISON OF AMERICAN CAR HEATERS. | | Name of Heater | Harrison "Twinflow" | Hadees H.{Arthur M. Hanbury - Head Complaints} 30 | Tropic-Aire Duplex. | |---|---|---|---|---| | | Trial No. | 631 | 632 | 633 | | Physical dimensions | Overall length | 8 1/4" | 7" | 9" | | | Overall Height | 8 1/2" | 9 1/2" | 7" | | | Overall Width | 7 5/8" | 7 1/2" | 6" | | | (Element length | 2.1/16" | 2" | 2.1/8") two | | | ( " Height | 6.1/4" | 6.1/8" | 4.5/8") off | | | ( " Width | 6" | 6.1/8" | 5" | | | (Dims: of Motors. | 3.1/16" o/casing) 4" o/all. 2.3/8" diam.) | 2.3/4" o/casing) 3.1/4" o/all ) 2.5/16" diam.) | 3" o/casing ) 4.1/2" o/all ) 3" diam. ) | | | (Fan diam. | 5.7/8" | 6" | 2 off 4.1/2" | | Weights | (Wt. of Heater | 6.125 lbs. | 8.75 lbs. | 11.75 lbs. | | | (Wt. of Element | 2.25 lbs. | 4.0 lbs. | 5.25 lbs for (2) | | | (Wt. of casing | 2.5 lbs. | 2.75 lbs. | 4.875 lbs. | | | (Wt. of motor | 1.0 lbs. | 1.25 lbs. | 1.625 | | | (Fitting parts (less hose) | .69 lbs. | 2.125 lbs. | 1.81 lbs. | | Trial details | (Volts | 12.0 | 12.0 | 12.0 | | | (Watts | 24.0 | 13.3 | 15.4 | | | (Water flow (galls. per min.) | 2.0 | 2.0 | 2.0 | | | (Water press. (ins. water) | 8" | 5" | 50" | | | (B.T.Us. at 120°F.{Mr Friese} T.D. | 8000 | 9000 | 9700 | | | (Air flow (cu. ft. per min | 135 | 130 | 115 | MOTOR PERFORMANCE WITH STANDARD 20° Angle bus heater fan. | | | | | | |---|---|---|---|---| | AT 12-VOLT | ( R.P.M. | 1250 | 1490 | 1760 | | | ( Equiv. B.H.P. | .0043 | .0072 | .0118 | | | ( Watts taken | 27.6 | 22.2 | 33.2 | | | ( Motor efficiency | 11.6% | 24.2% | 26.5% | | ||