Thanks!
Quote Originally Posted by Enemy Ace View Post
An EAA Webinar recently discussed two-stroke failure rates. It seems that the lowest rate of engine failure was in slow, draggy aircraft such as powered parachutes. Next highest was ultralights, followed by slow light aircraft such as trikes and Kitfoxes. Highest of all were clean, fast airframes. Seems that two-strokes can have a kind of lean-mixture runaway when the prop unloads, which is more likely in a fast plane (like a Dragonfly). Here's a link to the Webinar on Youtube: http://www.youtube.com/watch?v=GaaLb-BzqT4
I'd like to put in a plug for HKS: I've spoken with pilots who fly behind HKS engines and love 'em. Many of them flew two-strokes previously. . . .
This is the type of facts and data that help everyone move forward. It is only by looking at two-cycle failures that we can see if there are ways to mitigate the risks. I'll take a peek at the Webinar and see if I can contact the author(s) with my mitigation plan. I'll share what I learn here, later.

The HKS is still in the running because it just meets the range requirement. Unfortunately it is rated at 60 hp for only for three minutes. That is enough for take off and to gain a little altitude so it is still in the running if the 3502 preliminary design hits a show stopper.

My engineering practices require a fairly detailed design, a preliminary design review (PDR) that defines everything necessary for an engineering solution. It includes the parts list and prices. This Preliminary Design is then presented and if no 'show stoppers' show up, the parts are ordered.

BTW, I'm also working on what is called a Mission review but I'm not yet ready to publish in part due to being pretty busy an translating from NASA system engineering terms to 'human'. But it is a good exercise because it sets of goals that the PDR needs to cover the requirements.

Thanks!
Bob Wilson