Some comments regarding the various engines I have tested on Legal Eagle XL ORV. This includes the Hummel engines 45 hp 1/2VW, Verner 3V 3 cylinder radial, BSV23 (Briggs and Stratton Vanguard 23) and the BSV35, (Briggs and Stratton Vanguard 35). It should be noted the lighter a flying machine is, the more fun it is to fly. I have some time with a 60 hp full case VW on the Legal Eagle XL, very smooth operation but very heavy. I am only showing total weight of engines as I have been involved with. This includes engine, prop. prop bolts, engine mount bolts, engine mounts, exhaust pipes, oil tanks, hoses, carbs, batteries and anything else related to engine for a flying machine. The 1/2VW is a hand prop engine, it is very easy to do standing to side of machine and behind prop. When engine starts it pulls the machine away from you.
Engines with Starters are very nice for a variety of reasons. From an over all fun engine the BSV23 is difficult to beat. Easy starting, and no dripping oil out exhaust pipes or having to do anything special before starting. This engine has two magnetos, one for each cylinder and they do not required power to keep operating, just a ground to stop engine. The Verner 3V is my favorite with 42 hp at 2500 rpm, designed for aircraft usage, cruises with max gross weight at 2100 rpm at 2.1 GPH. Three cylinders with one CDI for each cylinder. If you do hot have power engine is not operating, generator power battery, battery powers CDI's. The 42 or 45 hp 1/2VW is a great engine with lots of them attached to aircraft. This engine generally comes with a magneto or 009 point type ignition (one used on automotive applications) as well as other types of ignition. The magneto provides spark as long as engine is operating so fuel is determining factor in flight duration. I cruised at 2800 to 2900 rpm at 2.4 GPH.
Regarding engine choices, it is very important to know what your flying objective is. Some people enjoy building but not so much the flying. Some people do not like the building but really enjoy flying. Some People only care about being in the air, not going anywhere in a hurry, just flying. Some people want to squeeze every ounce of power and performance out of engine and prop. Knowing where you fit and what you want to achieve as final product to enjoy is very important to understand. The LEXL is not a fast machine on best of days but it sure is fun just flying.
The average no wind cross country speed you see on GPS is 48 to 50 mph. My record with tail wind is 86 mph and with headwind is 18 mph.