fes ot jet (pros and cons)

On Monday, August 5, 2019 at 11:13:30 AM UTC-6, Steve Koerner wrote:
The beauty of the jet is good weight efficiency; at least for 100Km sort of range. Problems with the jet are slow startup; loudness and high RPM precision that necessitates a high degree of engineering perfection and production perfection to preclude start failure concerns.

The beauty of FES is fast startup and mechanical simplicity that should make it a very reliable alternative. The downside to FES is that batteries are expensive and heavy so range becomes a more difficult proposition. The other downside to FES is that drag in the folded prop position reduces glide performance.

A boom mounted electric is another alternative. Though a few seconds slower to get started compared to the FES and more complex in mechanization, the boom system eliminates stowed drag. A boom mounted electric also opens the possibility of self launch capability since the prop is not subject to nose over destruction nor FOD damage as would be the case for FES in self launch.

Both electrics and jets have safety concerns related to inflight fire that must be overcome with careful engineering and operational care by the user. Low production volumes make the safety issue harder than it would be if the engineering and testing efforts might be amortized over more units.

Steve, jet loudness is music to some ears Start failure concerns are more specific to certain manufacturers.

Sean Franke