On Thursday, March 31, 2016 at 3:14:00 PM UTC-5, Andy Blackburn wrote:
On Thursday, March 31, 2016 at 10:20:59 AM UTC-7, BobW wrote:
Major snip...

My apologies: I thought you were actually interested in discussion the
technical details of the design. I guess by your non-response my
calculations are correct...


They may be or they may not be, and if you're designing such a craft as Dale
Kramer is attempting, I've no doubt you can find qualified people to look over
your shoulder. This is America, have at it!

Given the original topic of this thread (which I took as a "Hey guys! Lookit
this...and oh by the way, here's how you can kick in some money if you're
sufficiently interested in funding further experimentation." sort of post),
"your calculations" seem to have become something of a
terribly-important-to-you sub-focus...probably more important to you than to
many/most of the original intended audience.

I offer this opinion as a degreed aerospace engineer having little
personal/user interest in hybrid VTOL flight, "hybrid" in this context meaning
capable of (some) verticality but of primarily "fixed-wings-based" horizontal
capability. Given today's materials, I simply don't see "serious practicality"
on any near horizon for it...similar in that sense to (say) man-powered
flight. Nevertheless, both are technically interesting (to many, including
me); both have been successfully performed; both will (probably) continue to
be investigated and perhaps even advanced (maybe even in my lifetime). And if
you somehow or other engage my interest sufficiently, I might even be
motivated into "calculation checking" beyond merely noting something I've
missed seeing anyone else note, i.e. that the "main prop atop" configuration
is arguably inherently stable in descending, vertically-oriented, flight
simply by the expedient of momentarily lessening "lower down" thrust. That's
not to suggest the physics of such flight are simple, but to rather suggest
the "balancing a pencil upon one's fingertip" analogy previously noted herein
is more appropriate for a rear-exhaust rocket than a "top-biased descender."

Respectfully,
Bob W.


Excellent points Bob.

I was thinking more that half the thrust was via electric motors down low and half was from the main reciprocating motor that put a lot of weight up high, but only half the thrust at the stable "on top" location, so it's a bit of a mix that could influence the dynamics of the transition from vertical to horizontal flight. I agree the balancing a pencil analogy really isn't proper for a number of reasons.



Andy

"VTOL is an heroic act, pretty much no matter how you go about it."
12-year olds with drones do it every day, thanks to cheap flight controllers containing super-cheap gyros and accelerometers. I can teach a caveman to fly one of those in 10 min.
Herb