[simpits-tech] Need a plan

[Matt Bailey]

On Thursday 27 January 2005 22:20, Bubba wrote:
>
> Think about this. The average car engine gets treated like crap (compared
> to aviation engines) and lasts many, MANY hours longer (150k miles is about
> equal to 300k hours!) I did find out that the Corvair engine does have a
> thrust bearing, too, so it's perfect.

	I was thinking more of the intended use..........look at the average 
automatic-tranny family sedan (or probably any van or Sorry Urban Vehicle as 
well). Most of the time it's barely over idle...ever notice the tach in a car 
with auto? It's pretty ridiculous to see it stay within like a 400rpm range, 
going between like 1200 and 1600 or so. And once the car gets going it 
doesn't need much power. RPM rarely gets close to redline. Compare this to an 
aircraft engine where you have to constantly throw out large amounts of 
torque at RPM's close to redline. I dunno, I think if you do it right you'll 
be fine, I'd just look into aviation-grade blocks first to see if anything 
would work. If it were me I'd feel a lot better with that setup.

> > I just looked it up.......cool looking plane! Only problem is it's a
> > side-by-side seater, and too fat. :P The KR1 I see is a single
> > seater, but it
> > looks like a bad cartoon knockoff of the RV-3.
>
> Actually it's too narrow for 2 people, so I'm going to put one seat right
> in the middle, wide armrests on both side with some room for misc. pilot
> crap, and a fairly large baggage compartment between the firewall and
> panel. Should have plenty of room for my crap.

	Oooh, sounds awesome. I guess when you say it's too small for "2 people", you 
really mean it's too small for two of you. ;) How about cup holders? Small 
freezer? Microwave? :)

> > Ah, a "functional" mock-up, good idea. :)
>
> I've been trying, with little success, to build a flight model and panel
> for FS9. The panel is pretty close to done, but I'm not even close with the
> flight model.

	Good luck...MSFS is an awesome program but its flight model is kludge'ness 
incarnate. Don't hold your breath on being able to achieve anything 
particularly representative of how your actual plane is going to fly (aside 
from generic data points like speeds for given altitudes, fuel consumption, 
etc...but then you would have to know this ahead of time in order to punch it 
into the flight model anyway, so the "prediction" value is virtually nil). Do 
dig into the .AIR files, deep. Change anything and everything, and remember/
note what it did (or what it did not do that you thought it should do).
	I get the impression that a number of parameters in MSFS aren't really very 
representative of the data point they claim to be. You'll probably find 
yourself associating each item a "supposed" behavior (according to the 
parameter its labeled as), then an actual behavior (the way the model is 
trying to approximate the real world effects of this parameter). Also, don't 
expect correct control response curves. If you dig enough, you *may* be able 
to massage the control-vs-AoA response curve to something less linear and 
mechanical than the average MSFS plane, but I doubt you can do too much. This 
is one of my biggest gripes with MS's flight model, and I spent some time a 
while back desperately trying to fix it, and I did do some weird stuff to the 
plane's behavior, but I never really could affet the basic response curve. 
There's just not enough in the model to tweak this into submission.
	If you really want to get a ballpark figure of how your plane is gonna fly 
and what kind of performance to expect, experiment with different airfoils, 
etc, X-Plane would be a better choice. It's a more ground-up approach. You 
punch in the geometry, foils, engine specs, etc, and the sim runs this into 
the flight model in a simplified, but for the most part, fundamentally 
accurate manner. Pretty much whatever changes you make, will affect 
performance in a realistic way. Got too much adverse yaw? Try moving the 
ailerons inboard, or mixing in some aileron differential, or using narrower 
chord ailerons, etc etc etc. Making a plane is a pretty pleasurable 
experience when you don't have to spend so much time trying to "figure out" 
the cheats and hacks the model is using, but instead can just apply real 
world aerodynamics concepts and logic to the problem and actually get the 
expected result. You won't have a dead-on perfect representation of the plane 
before you test fly the real thing, but X-Plane can give you a good idea of 
how things will shape up, and also can shed some light on the basic effects 
various design changes will have.

	-Matt Bailey