Temporary Gas Powertrain
Recently we decided to switch our powertrain from an electric engine with lithium-ion batteries to a gas-powered engine, at least temporarily. The main reason we decided to make the switch from electric to gas was in order to get the plane flying this summer. The electric engine and batteries require a lot more work and time than the gas engine. The gas engine will also be approximately $8,000 dollars cheaper than the electric one. There is a lot more research and information available on gas engines for planes than electric motors, which is good for our work. Another bonus is that a fuel tank is much simpler than a battery, so for our first flights we can focus on the other systems of the plane more. We plan to make the flight computer able to work with both types of engine, and make a universal mount for the nose so we can use any type of powertrain we want. We are going to convert the plane to electric after this summer which will be easy, because the plane is designed to have any type of engine.
We compiled many different engines that we have seen used before into a spreadsheet so it would be easier to compare them. We were looking for a really lightweight engine, but something that was powerful enough so that the plane can get off the ground. Our electric motor will be more powerful than the gas one so we just want something that we can use in the meantime. Throughout our research, the Hirth f33 and the Polini Thor 250 both stood out as the most recommended engines, and luckily they seemed like they could each fit our needs perfectly. We decided to choose the Polini Thor 250, which is a two stroke single cylinder engine. It is very light and has been used a lot before on ultralight planes, so there is a lot of research available to us. It is also a cheaper option that is easily acquirable while fitting our other needs, so we thought that it is the best for our use.
Sensors and Next Steps
The sensors we have decided to design and use for our powertrain system are a rpm sensor, a temperature sensor, a fuel gauge, and a battery voltage sensor. Design and electrical teams have been working very closely together for the powertrain, and this is a good example of a task that has moved from a project in the design team’s domain to one in electrical. We hope that these sensors will be enough to give the pilot enough understanding of the data they need to know, and these sensors will enable us to keep the plane running smoothly with no surprises.
Powertrain team’s next steps are to find or design our gas tank, and retrieve all the materials necessary for our fuel system, including tubing, fuel filters, and cutoff switches. We are looking forward to when our engine arrives, so we can complete and test our sensors and throttle system.