HF Systems

Due to the fact that existing engines in the market did not fulfil the high standard of 3W-Modellmotoren GmbH, management decided to start their own project for a heavy fuel solution. In 2007, the company began to research and develop its first heavy fuel engines.

Several developments were made and tested until the R&D department decided on the final engine design. The crankcase was pre-heated for the cold start by using cartridge heaters. The air intake section and carburettor were modified, too.

One-cylinder engines were fitted with a particularly shaped muffler with an integrated heat collector, which accepts cartridge heaters. The two and four-cylinder engines were fitted with a heat collector, designed to accept the suitable cartridge heater.

After the first prototypes had been produced, the engines were tested under various severe conditions. At the test-facility of 3W-Modellmotoren GmbH, the engines had to run without difficulties in an ambient temperature of +45°C, including restarts. To simulate low temperatures, a 5l tank with JET A-1 was stored at -18°C in the deep freezer overnight. Even given these conditions the engines were started without any problems.

The combination of these modifications and the new development constituted the breakthrough in heavy fuel technology. The engines proved their outstanding reliability during the extensive test runs – securing
PERFORMANCE BEYOND LIMITS.

Twin spark option

All engines beginning at 55 ccm can be delivered as a twin-spark (TS) version. Both ignitions work independently of one another here.
The following benefits can be achieved using the TS version:

• The engine runs at a lower idle; general operational behaviour is quieter.
• Safety and reliability increase in both single- and multiple-cylinder engines when using the TS cylinder.
• When one ignition fails, the second ignition working independently ensures that the engine continues to run with slightly reduced RPM.

Standard Options

The programme for the break-in procedure can be modified to meet the end user’s specifications. For engines with less 3.30 cu in cylinder capacities, manually operated compression release valves are standard and make for an easy start of the engine. For engines with a cylinder capacity of 20,68 cu in and more , manually operated compression release valves are standard. This will reduce the load of the crankshaft if an external heavy-duty electrical starter is used. In addition, the engine can be easily stopped and restarted while the craft is in the air. This requires an on-board starter or an alternator/starter unit. Upon request request, automatically operated compression release valve can be fitted. The engine mounting plate is designed for mounting an additional 4th ball bearing to support the rear output shaft. Only the mounting plate needs to be redesigned if an alternator or starter unit is used. Generator mounting plates for Bental and Sullivan units are available for 3W-110xiB2 TS HFE FI and 3W-157xiB2 TS HFE FI, 3W-170xiB2 TS HFE FI as well as 3W-210xiB2 TS HFE FI. The rear output shaft is a standard feature and allows for mounting of: alternators, electric starters and starter/alternator units. This standard option is not applicable for rear induction engines. The patented 3W-mufflers are recommended to reduce the noise level. 3D models are available upon request.