Jim Wilson wrote:
Actually I tried all the way up to 80,000lbs and still ran into
problems in the 25000ft range. There is a little uncertaintly in just
what I'm observing. Basically there is a steady decrease in
attainable airspeed.
I found one bug. There was a property name typo* in
Major A wrote:
This may or may not have anything to do with the jet code, but with
the 747-yasim, I cannot slow the plane below about 280kt in level
flight at 3000ft ASL with throttles at minimum and full flaps, which
makes the plane rather hard to land...
By way of disclosure: there is a
Jim Wilson wrote:
There should be speed brakes which would have helped a lot, but they
might not be implemented yet.
Sure are: /controls/spoilers
There are also a bunch of flaps on a real 747 and I'm not sure which
ones are actually modeled.
All of them; YASim models flaps symbolically as
Andy Ross [EMAIL PROTECTED] said:
Does anyone have good, hard climb numbers for this plane? I mean
stuff like: At NNN pounds gross weight, XXX feet MSL and YYY knots
TAS, the 747-400 can climb at ZZZ feet per minute. My suspicion is
that we're being bitten by a combination of bad
Andy Ross [EMAIL PROTECTED] said:
Jim Wilson wrote:
On the other hand it could be lift. A possible clue: when I'm having
trouble the mach reading seems to be way too high as compared to the
KAIS reading just above. Examples:
@ 19000ft 419KIAS MACH=0.91
@ 23000ft 344KIAS MACH=0.83
Jim Wilson wrote:
Think I saw something that was maybe at a fixed weight. Not the full
Flight manual table. When I get home I'll look for it. But I was
suprised at the data. At lower altitudes it was over 4000fpm and was
at least 2000fpm up to and over 3ft. Finally dropped off to
Jim Wilson wrote:
Yeah but look at the values again...we're getting close to tropopause
value at 23000ft. Mach should be well over 600knots at 23000ft,
unless it's _really_ warm.
Mach 1 at the tropopause and above is just about exactly 295 m/s,
which is 573 knots *true* airspeed. The
--- Jim Wilson [EMAIL PROTECTED] wrote:
Andy Ross [EMAIL PROTECTED] said:
Jim Wilson wrote:
On the other hand it could be lift. A possible
clue: when I'm having
trouble the mach reading seems to be way too
high as compared to the
KAIS reading just above. Examples:
@
Andy Ross [EMAIL PROTECTED] said:
Jim Wilson wrote:
Think I saw something that was maybe at a fixed weight. Not the full
Flight manual table. When I get home I'll look for it. But I was
suprised at the data. At lower altitudes it was over 4000fpm and was
at least 2000fpm up to and
Andy Ross [EMAIL PROTECTED] said:
Jim Wilson wrote:
Yeah but look at the values again...we're getting close to tropopause
value at 23000ft. Mach should be well over 600knots at 23000ft,
unless it's _really_ warm.
Mach 1 at the tropopause and above is just about exactly 295 m/s,
which
Andy Ross writes:
Does anyone have good, hard climb numbers for this plane? I mean
stuff like: At NNN pounds gross weight, XXX feet MSL and YYY knots
TAS, the 747-400 can climb at ZZZ feet per minute. My suspicion is
that we're being bitten by a combination of bad performance numbers
David Megginson [EMAIL PROTECTED] said:
Andy Ross writes:
Does anyone have good, hard climb numbers for this plane? I mean
stuff like: At NNN pounds gross weight, XXX feet MSL and YYY knots
TAS, the 747-400 can climb at ZZZ feet per minute. My suspicion is
that we're being
OK, I *think* I have nailed the platform-dependant YASim solution
failures. What I found was that the solution heuristics hid a bunch
of pseudo-chaotic instabilities that were introduced when the approach
elevator trim feature went in a few weeks back. This was
deterministic, but weird --
Andy Ross [EMAIL PROTECTED] said:
Anyway, try the new code and see if that works for you. You'll also
want new planes, as some of the old ones went pretty wacky once the
fix went in:
http://www.plausible.org/andy/yasim-aircraft-052902.tar
Andy that works. Haven't been able to
Jim Wilson wrote:
Andy that works. Haven't been able to download your tar ball (is the
link correct?).
Sigh. Long story: plausible.org is a box in my closet. We lost power
last night. It has a dumb (Asus P5A) ATX motherboard that doesn't
know how to power on following a power loss (it
On Wed, 29 May 2002 10:05:07 -0700
Andy Ross [EMAIL PROTECTED] wrote:
last night. It has a dumb (Asus P5A) ATX motherboard that doesn't
know how to power on following a power loss (it comes up in soft-off
You sure you don't have a BIOS setting for that? I've got
one on my m/b. Maybe you need
Andy Ross wrote:
Jim Wilson wrote:
It appears that the thrust/altitude curve is a bit too steep. [...]
Also there seems to be a greatly exagerated ram effect (not sure of
correct term). It seems that airspeed changes might be affecting the
thrust value too greatly, but I don't have a feel for
Jon S. Berndt wrote:
Andy Ross wrote:
last night. It has a dumb (Asus P5A) ATX motherboard that doesn't
know how to power on following a power loss (it comes up in soft-off
You sure you don't have a BIOS setting for that? I've got one on my
m/b. Maybe you need to upgrade your BIOS?
Andy Ross writes:
OK, this doesn't surprise me too much. I haven't examined the Jet
stuff very closely. The way the code works is that it matches some
performance curves I got out of McFarland for a 707 engine. The
turbofans on the 747 actually won't be too terribly far off in their
David Megginson wrote:
Andy Ross writes:
The way the code works is that it matches some performance curves I
got out of McFarland for a 707 engine. The turbofans on the 747
actually won't be too terribly far off in their thrust performance,
I'd think.
This is probably a dumb question,
[At supersonic speeds, lots of stuff is happening that won't be
modelled well by the current code at all. The F-15C that I did for
Gene, for example, was reading 130% N1 RPM at mach 2 or so. :)]
Say what?! When did you do this? Did you take the DECC/ECC into account?
:)
g.
Andy Ross writes:
Anyway, try the new code and see if that works for you. You'll also
want new planes, as some of the old ones went pretty wacky once the
fix went in:
http://www.plausible.org/andy/yasim-aircraft-052902.tar
I'm checking these in now.
All the best,
David
--
I wrote:
Jim Wilson wrote:
It appears that the thrust/altitude curve is a bit too steep. [...]
Also there seems to be a greatly exagerated ram effect (not sure
of correct term). It seems that airspeed changes might be affecting
the thrust value too greatly, but I don't have a feel for
OK, I've examined the jet code a bit more closely, and it actually
looks pretty good to me. Attached is a graph of available thrust
vs. speed and altitude for the engines as modelled on the 747-400. I
threw together a little program that looped over the Jet object, and
played with
Major A [EMAIL PROTECTED] said:
OK, I've examined the jet code a bit more closely, and it actually
looks pretty good to me. Attached is a graph of available thrust
vs. speed and altitude for the engines as modelled on the 747-400. I
threw together a little program that looped over
This may or may not have anything to do with the jet code, but with
the 747-yasim, I cannot slow the plane below about 280kt in level
flight at 3000ft ASL with throttles at minimum and full flaps, which
makes the plane rather hard to land...
Legally you shouldn't be up to 280kt at
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