OK, it's a week later than I would have liked, but I've finally
reached a good stopping place with YASim, and have a new release
ready. Highlights:
Engine glitz. The jets now spool slowly over time, rather than
responding instantly to throttle input. They also report useful and
correct values for N1, N2 percent, EGT, and engine pressure ratio in
the ("/engines/engine[n]/") n1, n2, egt-degf, and epr properties.
Unfortunately, I don't have a panel that actually displays these
values. I'm hoping someone with more artistic skill will be willing
to try something. You can read the values out of the property picker
if you're curious.
Also, the piston engine has had a few things added. It now reports
manifold pressure, EGT and fuel flow correctly. There's still no way
to shut down or start up the engine, but in-flight behavior should be
more or less feature-complete.
New airplane #1: a DC-3. This has a settable supercharger, as was
discussed a week or so ago. The /controls/boost[n] property control
the "amount" of the supercharger that is engaged. I have it set to a
3-click "mode" switch on my throttle to map to: 0, 0.5 and 1. It
flies quite well, and feels the way I would expect it to. Being a
taildragger, it's a real chore to land without bouncing all over the
place. Unfortunately, until I get prop wash implemented, it's going
to be nearly impossible to taxi. On a real plane, you'd use the
prop-enhanced rudders and differential braking to steer. Not having
toe brakes, I had to map the braking to the "outer" ranger of the
rudder. This means that until you get up to speed, there's very
little steering authority in the middle of the rudder range. You have
to swing the pedals all over the place; I ground-loop probably one
takeoff in three. The upside, however, is that ground loops in the
tail dragger really do happen. :)
New airplane #2: A Sea Harrier FRS.1. I've told folks before of my
weakness for carrier aircraft, and since the carrier model (the
Vikrant, I think) we have has a ski jump, and since vectorable thrust
is really easy to code, I just couldn't resist. This thing rocks.
It's also VERY hard to fly. I haven't succeeded at making a true
vertical landing yet (the hover turns into a PIO-like wobble, the
plane tips over on its side and the results aren't pretty), although
I'm getting pretty good at putting it down on the numbers at 30-40
knots or so. The thrust vectoring is mapped to
/controls/thrust-vector[n], which I put on the same rotary dial I use
for Mixture.
The control mapping is much more robust. You can now map any
sub-range of a given input to any range of the output variable. The
Harrier's reaction jets use this -- they produce thrust only when the
elevator (or whatever) is in one half of its travel. The DC-3 also
uses this trick to good effect to map the 0.5-1.0 range of the rudder
travel to differential braking.
General work on the existing planes. The 747-400 now has working
slats and spoilers (mapped to /controls/{slats|spoilers}, heh). The
172 has been matched to the 172R data that David put in the base
package, and it is now a little less nimble (I had typoed the stall
speed). Conversely the A-4 is significantly more nimble (AoA "units"
aren't the same thing as degrees, apparently). All of the planes
respect the elevator/aileron/rudder trim properties, regardless of
whether or not they have such controls in the cockpit.
Lots of minor augmentations: The mass distribution generation is saner
now, and requires less ballast tuning in typical usage. Fuselages can
have a "taper" and "midpoint" fraction defined (they used to be plain
cylinders), again to make the mass distributions come out better.
Gear can be castering now; the DC-3's tail wheel needed it. I cranked
up the iteration rate by a factor of four, the performance problems I
was worried about turn out not to exist. This makes ground handling
much less jiggly. David's complaints about crosswind taxiing have
largely been addressed, I think.
The code should be in CVS soon, but planes need to go in the base
package. Until they get there, you can get them here (note that the
src package contains two new files: SimpleJet.[hc]pp). Untar the
source files in your <fgfs>/src/FDM/YASim directory, the planes go in
the top-level of your base package.
http://12.232.180.89/andy/yasim-src-20011223.tar.gz
http://12.232.180.89/andy/yasim-planes-20011223.tar.gz
Curt: I'm still having trouble with CVS access; can you try blowing
away the .ssh directory I mistakenly installed, and maybe check
permissions on the accounts home directory? I suspect I fouled
something up...
And, finally, I'm going to be in Boston for the next two weeks. While
I'll be reachable via email, I sadly won't likely have a machine
available on which to play with FlightGear. Happy holidays, everyone.
I'll catch up when I get back.
Andy
--
Andrew J. Ross NextBus Information Systems
Senior Software Engineer Emeryville, CA
[EMAIL PROTECTED] http://www.nextbus.com
"Men go crazy in conflagrations. They only get better one by one."
- Sting (misquoted)
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