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).
Recent aircraft ignition developments, including weight comparisons of various systems and specifications for an ideal system.
| Identifier | ExFiles\Box 37\1\ scan 170 | |
| Date | 1st July 1927 | |
| Vol. XXI July, 1927 No. 1 RECENT AIRCRAFT-IGNITION DEVELOPMENTS 39 the generator capacity, it may be pointed out that, for the largest generator now in service, which has 50-amp. WEIGHT OF IGNITION SYSTEM Liberty-Delco 8-Volt System for Liberty-12 Engine Lb. 2 Ignition-Distributors 10.5 1 8-Volt Battery 11.0 1 Switch and Voltage-Regulator 2.1 1 8-Volt Generator 11.5 Total 35.1 Dixie 800 Magneto for Wright E Engine 2 Dixie-800 Magnetos 33.6 2 Drive Assemblies and Mounting-Bracket¹ 12.0 1 Starting-Magneto 8.1 1 Switch 1.2 Total 54.9 Delco Ignition-Distributor on Curtiss R-1454 Radial Air-Cooled Engine 1 Ignition-Distributor Assembly 13.4 1 Switch¹ 1.0 Total 14.4 Splitdorf-PA{Mr Paterson} Double Magneto on Curtiss R-1454 Radial Air-Cooled Engine 1 Splitdorf-PA{Mr Paterson} Double-Magneto 18.5 1 Dixie-100 Starting-Magneto 8.1 1 Switch 1.2 Total 27.8 Delco Ignition-Distributor on Curtiss D-12 Engine 2 Delco Ignition-Distributor Assemblies 10.0 2 Distributor-Drive Assemblies and Adapters 5.5 2 High-Tension Coils 4.4 1 Switch¹ 1.2 Total 21.1 Splitdorf SS{S. Smith}-12 Magneto on Curtiss D-12 Engine 2 Splitdorf SS{S. Smith}-12 Magneto 28.2 2 Coupling and Drive Assemblies 3.0 2 Mounting-Brackets¹ 2.5 1 Switch 1.2 1 Starting-Magneto 8.1 Total 43.0 Splitdorf VA-1 Double-Magneto on Curtiss D-12 Engine 1 Splitdorf VA-1 Magneto 15.5 1 Magneto Adapter-Flange and Drive-Coupling 1.9 2 Distributor-Drive Assemblies 4.5 2 Distributor-Heads and Rotors 3.0 1 Switch 1.2 1 Starting-Magneto 8.1 Total 34.2 Delco Ignition-Distributor for Packard 1500 and 2500 Engines 2 Ignition-Distributors 10.0 2 High-Tension Coils, Type D 4.4 1 Switch 1.0 Total 15.4 Scintilla AG 12-D Single Magnetos on Packard 1500 Engine 2 Scintilla-AG 12-D Single-Magnetos 29.8 2 Coupling and Drive Assemblies 3.0 1 Mounting-Bracket¹ 12.0 1 Switch 1.2 1 Starting-Magneto 8.1 Total 54.1 ¹ Estimated. ² Not including generator or battery weight. FIG. 15—DISTRIBUTOR FOR 12-CYLINDER 60-DEG. V-TYPE ENGINES This Was Developed To Meet the Requirement for a Light Compact High-Speed Battery-Ignition System for Airplanes That Carry Other Equipment Requiring a Generator and Battery. It Was Designed for Driving from the Camshaft. Drive-Shaft-Housing on the Packard 1500 and 2500 Engines but Can Be Adapted to Different Engines without Difficulty. The Principal Design Features Are a 12-Lobe Cam with Double Breakers, an Air-Gap Distributor and Separate Ignition-Coils capacity, this burden amounts to only slightly more than the weight of a starting magneto. From the foregoing tabulation, it is seen that battery ignition, exclusive of generator and battery, weighs less than one-half that of the equivalent magneto-ignition, when two single magnetos are used, and not more than two-thirds as much, when a double magneto is considered. With an ignition battery and generator, the battery ignition-system has about the same weight as the double-magneto installation. IDEAL IGNITION-SYSTEM Based on the requirements of the types of military and commercial aircraft now in service and proposed for the future, the ideal ignition-system should have the following characteristics: (1) A rugged light compact source of sparks (2) Flange mounting (3) Bearings large enough to allow a direct splined shaft or gear drive (4) Complete enclosure of the ignition system in a metallic housing conforming to the space available on the engine (5) Secondary cables carried in substantial metallic housings preferably built into the cylinder-block and connected directly to the distributor housing, without flexible braid or tubing, thus providing radio shielding and mechanical protection and eliminating the fire hazard (6) Ignition drive from the propeller end of the crankshaft to eliminate drive stresses (7) Ignition for starting direct from the “running” magneto without the use of booster magneto (8) Electrical insulation for supercharging to at least 20,000 ft. (9) A normal life, without lubrication, adjustment or cleaning, greater than the time between the major overhauls of the engine | ||