DS and DP //Re: [AWES] Re: Airfoil "Curvature Control" as a Makani Design Driver
- Brian,Sorry. The reason to hope that DS was understood on the forum is the fifty or so old messages dealing with the topic. While your eagerness to defend Makani in technical debate is very laudable, the limited preparation is bound to have some effects, and is totally excusable.Its impractical for a "professional level" AWES forum to be easy for everyone to understand. DS is of course well understood by RC pros, and RC is just one of the many fields we must be masters of!As you can see better now, inverse DS (DP- Dynamic Plummet) in a not-too-rare inverse surface wind gradient is something serious to ponder for high-mass high-speed looping kiteplane operations,daveS
- Hugh tells me his generators will never make as much power as mine since he uses no iron. His approach is all about smooth operation and home-buildability. He's looking for consistent charging and reliability whereas I'm building hot-rods. Grandpa isn't going to burn out the engine in his econo-box sedan - if you wanna see a lot of blown engines, go to a race track! Racing technology filters eventually to better performance in Grandpa's sedan.
--- In AirborneWindEnergy@yahoogroups.com, Robert Copcutt <r@...> wrote:
> My experience is that when you hit a persistent problem
> you can either apply brute force to it (eg. build bigger generators) or
> you can swot up more on the theory and find an optimal solution. The
> fact that you have had so many generators burn out tells me that you
> never got around to developing a comprehensive computer model telling
> you what is going on with them. To burn out 1 is a lesson. To burn out
> several shows that there is a missing link in your chain of logic.
> It is magnetic hysteresis that creates the heat. If the iron is sent
> beyond saturation then the hysteresis rapidly increases. However, it is
> always there which is why Hugh Piggot went for air-core generators so
> that the turbines could spin up under minimal resistance to start
> catching the wind. Air-core machines can be way more efficient (98% has
> been demonstrated) than iron-core ones (usually <90% unless very big). I
> am in the process of working out if Visventis would be better of with
> air or iron cores; or pancake or a more square format.
> On Fri, 2012-05-18 at 02:17 +0000, Doug wrote:
> > Where do you get all this? Sound in error to me and I make generators
> > and run them and measure them all day every day.
> > How could you profess to have such a comprehensive knowledge of
> > motors, and yet you say you wonder why pancake motors are not
> > universal?
> > Isn't that like Dave S., the world's latest leading authority in wind
> > energy, asking why turbines don't use kites? Like motors used to be
> > pancake-style, turbines used to use kites as blades. Then progress
> > happened.
> > Pancake motors were universal when the concept of a motor first came
> > about, then it took a few weeks til they figured out how to do it
> > better using less materials.
> > Oh, and another thing,
> > Magnetic saturation in your laminations can cause heat and help burn
> > out your coils. Take it from the king of burned out generators!
> > Umm, listen, I'm really sorry to tell you this but, again, everyone is
> > entitled to their own opinion but not our own facts.
> > Motors and generators produce power in proportion to the square of
> > their RPM and that is just a simple well-known rule of thumb.