Been a few years but the turbocharger was the biggest issue. SMA thought they could scale it up in a linear fashion to produce desired performance (the STC version of that engine had a critical attitude of sea level and a maximum approved altitude of 10,000’ iirc). The first part of the test program was to prove them wrong. And that was a success.

Also, systems integration was challenging. Finding a prop and governor that would play nice with the SMA wasn’t quite ever figured out. Really, the difference in engineering cultures between the two companies could be summed up by the two G1000 messages the engine would send. “ECU MINOR FAULT” and “ECU MAJOR FAULT.” One means the engine might quit and the other means it probably will. All that SMA thought a pilot needed to know.

I can imagine how some investors will continue. Internet fanboy culture ... and a lack of technical appreciation or knowledge.

I worked on the J182 program. You’re a large multiple above the actual number. A two digit multiple. But any were too many.

I’m guessing flameouts versus off-airport landings is the difference.

And yeah...if they couldn’t get an aircraft diesel with an acceptable level of performance and reliability certified, this guy is out to lunch!

How do you characterize FAA involvement in the program?

None after the airworthiness inspection, until he seeks certification. Then a lot.

My question (thread drift) was asked in the context of the Cessna/SMA certification work. As a program engineer described FAA's participation to me ... FAA was substantively unhelpful.

I apologize for the thread drift and will take it to PM.

My opinion: Peter doesn't know, what he doesn't know and cannot imagine that it is perhaps "complicated."

Nope

Peter's hypothesis appears to be that the open gear wells create some aerodynamic effect that creates the instability. Perhaps so, but there are several other possibilities as well. I wonder about the elevator trim spring being too soft or the excess deflection on the ailerons that it is not clear was resolved. Rather than retract the gear, it seems to me he could build some covers for the wells to test his theory.

Not to overstate the obvious, but he's got himself in a tough spot, with glaring stability and propulsion issues to solve.

I’m curious about the elevator hinging he used on the Raptor. With the hinges located well below the canard wouldn’t that change the control surface gap a lot as he changed stick position which would cause it to change pitch control pressure.

Other airplanes hinge ailerons this way but with two linked opposing aileron surfaces it may cancel out the changes in feel. They also have hinges much closer to the bottom surface.

It might be the correct hinging for a flap system but not for a control surface. Did he ever give a good reason for hinging the elevators this way?

Just eyeballing to compare with other successful past canard designs the canard appears to be too short of a span.

I’m an amateur, but isn’t there some fluid dynamics software available at a somewhat reasonable price that would be able to predict this sort of thing? I know it has been used on larger aircraft for decades, and my iPhone could probably run the simulations they used for the 777.

X-Plane

If the software result differed from Peter’s expectations he would blame the software or decide that some input was wrong.

Duct tape would close the gear holes up in about 6 minutes. Maybe $11 in materials.

He is using Solidworks. One thing I have noticed from being involved in engineering software tools for 20+ years is that some people seem to expect the software to do the thinking for them. I have noticed from the deflections that Peter does not have a solid grasp of the FEA module. I expect that he is similarly lost with the CFD module.

The result outputs from both of these modules need to be carefully considered - there is more to it than looking at the numbers and hoping it will work.