Re: [Jsbsim-devel] C-172 Performance --- More comments

[Jon S B. <js...@ha...>]

On Thu, 14 Oct 2004 09:18:40 -0700
  "Gregory Pierson" <gpi...@so...> wrote:
> David

> No offense, but this attitude will doom JSBSim to failure.
> 
> When you start using excuses to lower the quality of your input 
> data, doesn't it invalidate all the high quality equations in JSBSim 
> all of you have worked so hard on?

No, no, no. I think you've missed his point. Let me put it this way: 
we'll have users (who really _know_) scream and holler if our C-172R 
gets 123 knots at sea level if a real C-172 only gets 115 knots, 
**regardless** of what the propaganda at Cessna.com says. As was 
mentioned, too, no two aircraft will really get the same performance 
due to any number of things. In some cases, the only information we 
will have will be manufacturers data (their ideal performance, as 
published for marketing purposes) - then we'll have to use that.

The key point is to make sure that whatever aircraft we model, that we 
specify what that model represents (even down to the serial number if 
need be). That means: which aircraft, which year, which version, which 
block, which engine/prop, etc. Because, this matters. Once we know 
what we are modeling, then we have to decide what we are trying to 
match - and we can choose what we desire to choose here: an ideal 
off-the-production-line vehicle, or a beat-up worn-out dusty workhorse 
of a specimen. That's the modeler's choice. And she will craft the 
aero and mass properties based on whatever information can be found. 
It's as much art as it is science.

Jon