Re: [Jsbsim-devel] C-172 Performance

[David M. <dav...@gm...>]

On Tue, 12 Oct 2004 19:41:30 -0500, Jon Berndt <js...@ha...> wrote:

> Before I say too much on what might be wrong, I'm going to run more tests. I have weighed
> down the vehicle to a GW of 2450 lbs (per Cessna.com) and am trying to match the
> performance from the Cessna web site. I can only make an attempt to match the takeoff
> procedure, though, because I don't know it. I figure one notch (10 degrees) of flaps might
> be worthwhile. Some enlightenment on validating takeoff performance is solicited.

From the POH: 10 degrees flaps, break ground as soon as possible (say,
45-50 kias), accelerate in ground effect, then climb out at 57 kias
until all obstacles cleared.  In real life, it's normal to hear to
stall horn when you break ground, so don't be surprised if you hear it
in FlightGear as well.

> One thing that I have noticed is that even at full power the IO360 puts out only 120 HP.
> It is supposed to put out 160.

In fact, the 172r's IO360 is a 180 hp engine, derated to 160 hp and
2400 rpm; the 172p has a 160 hp O320.  In both cases, because of the
fixed-pitch prop the engine will develop full rated horsepower only at
sea level and a relatively high forward speed -- maximum static
horsepower will be considerably lower (i.e. you'll never see anything
close to maximum power from the plane when it's standing still, even
with full throttle).


All the best,


David

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http://www.megginson.com/