This would be good to see in a plot. Can you do that?
Jon
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From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Alex Romosan
Sent: Saturday, September 06, 2008 5:06 PM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] f16
Jon S. Berndt writes:
This would be good to see in a plot. Can you do that?
i guess jsbsim can do it but i never tried it. any pointers?
--alex--
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| I believe the moment is at hand when, by a paranoiac and active |
| advance of the mind, it will be possible (simultaneously with |
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On Fri, Sep 5, 2008 at 11:54 PM, Erik Hofman [EMAIL PROTECTED] wrote:
I also see that (I'm only looking at the speedbrakes effects).
Two things are unclear for me:
1. The values of alpha in f16.xml are exactly half those in NASA's
TP1538 report.
2. The values of the coefficients are
Jon S. Berndt writes:
I don't know if this matters, but remember that not too long ago we
added the ability to enter aero coefficients in several coordinate
systems - including BODY and WIND, etc.
so if i were to represent the wind tunnel data in x,y,z axis then the
drag due to horizontal
On 9/4/08, Alex Romosan [EMAIL PROTECTED] wrote:
Erik Hofman writes:
Alex Romosan wrote:
can you give me a pointer as to where i could get this data? thanks.
Search for NASA Technical Paper 1538
i've been looking at it but i can't figure out the relationship
between the number in the
Fabian Grodek wrote:
On 9/4/08, *Alex Romosan* [EMAIL PROTECTED]
mailto:[EMAIL PROTECTED] wrote:
Erik Hofman writes:
Alex Romosan wrote:
can you give me a pointer as to where i could get this data? thanks.
Search for NASA Technical Paper 1538
i've
Of course you need to transform the data from body axes to wind axes
first..
Erik
I don't know if this matters, but remember that not too long ago we added
the ability to enter aero coefficients in several coordinate systems -
including BODY and WIND, etc.
Jon
Erik Hofman writes:
Alex Romosan wrote:
can you give me a pointer as to where i could get this data? thanks.
Search for NASA Technical Paper 1538
i've been looking at it but i can't figure out the relationship
between the number in the report and the numbers in the flightgear
model. if
On 8/30/08, Erik Hofman [EMAIL PROTECTED] wrote:
... But I don't see any pitching moment effect; from
what I see in NASA TP 1538 http://hdl.handle.net/2002/11034 I
understand there is a pitch-down effect from the speedbrakes.
It looks like you don't have the latest version of the
On Sun, 2008-08-31 at 12:31 +0200, Fabian Grodek wrote:
On 8/30/08, Erik Hofman [EMAIL PROTECTED] wrote:
... But I don't see any pitching moment effect; from
what I see in NASA TP 1538
http://hdl.handle.net/2002/11034 I
understand there is a pitch-down
Alex Romosan wrote:
can you give me a pointer as to where i could get this data? thanks.
Search for NASA Technical Paper 1538
Erik
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Fabian Grodek wrote:
Erik,
In the F16 aero config file I see there's indeed an increase in lift
for certain speedbrakes deflection, accompanied by the expected huge
increase in drag. But I don't see any pitching moment effect; from
what I see in NASA TP 1538
Erik Hofman writes:
Alex Romosan wrote:
can you give me a pointer as to where i could get this data? thanks.
Search for NASA Technical Paper 1538
thanks.
--alex--
--
| I believe the moment is at hand when, by a paranoiac and active |
| advance of the mind, it will be possible
Alex Romosan wrote:
i hate to bring this up again but i still think the speedbrakes don't
work as they should, instead generating quite a lot of lift. i've
tested this on final approach at about 160-170 knots, speedbrakes on;
i can keep the plane level. retract the speedbrakes, the plane
Erik Hofman writes:
Believe me, this is correct behavior, and this is why:
i found a nice article about flying in an f16:
http://www.avweb.com/news/skywrite/181916-1.html
this is the part about the speed brakes:
Here's where the speed brakes come in handy, I'll open em up. And
you'll
Alex Romosan wrote:
Erik Hofman writes:
Believe me, this is correct behavior, and this is why:
i found a nice article about flying in an f16:
http://www.avweb.com/news/skywrite/181916-1.html
this is the part about the speed brakes:
Here's where the speed brakes come in handy,
Erik Hofman writes:
Alex Romosan wrote:
I felt what happens! It seemed my face was being pulled from my
skull. I couldn't believe how effective those speed brakes were. An
F-16's speed brakes are located at the back of the fuselage either
side of the engine nacelle, and really look
On ven 29 août 2008, Erik Hofman wrote:
Alex Romosan wrote:
Erik Hofman writes:
Believe me, this is correct behavior, and this is why:
i found a nice article about flying in an f16:
http://www.avweb.com/news/skywrite/181916-1.html
this is the part about the speed brakes:
gerard robin wrote:
A Only my 2 cents, if the question is not stupid :)
How does the fly-by-wire, regarding the speedbrake lift effect ?
What happens (with regard to the fly-by-wire system) is this:
Speedbrake deflection causes a pitching moment which the FCS
automatically compensates
Alex Romosan wrote:
Erik Hofman writes:
Alex Romosan wrote:
I felt what happens! It seemed my face was being pulled from my
skull. I couldn't believe how effective those speed brakes were. An
F-16's speed brakes are located at the back of the fuselage either
side of the engine
Erik Hofman writes:
Sorry, I got the data from windtunnel test data performed by NASA.
can you give me a pointer as to where i could get this data? thanks.
--alex--
--
| I believe the moment is at hand when, by a paranoiac and active |
| advance of the mind, it will be possible
Ok, I think I have most of it figured out. I might even consider
upgrading the status to 'production' the way it is now.
Erik
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Erik Hofman writes:
Ok, I think I have most of it figured out. I might even consider
upgrading the status to 'production' the way it is now.
hmm, i don't know how the real f-16 behaves but i still find the
current behaviour a bit strange. level flight, ~350 knots extend the
brakes the
Alex Romosan wrote:
hmm, i don't know how the real f-16 behaves but i still find the
current behaviour a bit strange. level flight, ~350 knots extend the
brakes the aircraft pitches up slightly and really starts to climb (no
effect on the speed at all). push the nose down (quite a lot) to
Ok, tested it again. The only way I could reproduce your scenario is not
to have the throttle near idle.
As I did state earlier, the speeedbrakes of the F-16 are quite small and
as it turns out the engine can easily produce enough thrust to overcome
the increased drag.
Erik
Erik Hofman writes:
Ok, tested it again. The only way I could reproduce your scenario is not
to have the throttle near idle.
As I did state earlier, the speeedbrakes of the F-16 are quite small and
as it turns out the engine can easily produce enough thrust to overcome
the increased drag.
Erik Hofman writes:
You were right, I had to map speedbrake-pos-norm to
speedbrake-pos-rad/deg by using an aerosurface scale section.
i think there is still something wrong with the speedbrakes but i am
not sure how to quantify this. basically i think they provide way too
much lift (which
Alex Romosan wrote:
i think there is still something wrong with the speedbrakes but i am
not sure how to quantify this. basically i think they provide way too
much lift (which makes me suspect there is a sign problem somewhere).
the effect is more pronounced at slower speeds (250 - 300 knots
Alex Romosan wrote:
i noticed that on the f16 the speedbrakes have no effect at all and i
managed to track it down to the fact that the various coefficients use
fcs/mag-speedbrake-pos-rad on input which never gets set anywhere (so
it is always 0).
digging through the cvs logs i found that
Erik Hofman writes:
Looking at the code it looks like setting speed-break-pos-norm should be
the same as setting speed-break-pos-rad so the patch shouldn't have any
effect.
look at aero/coefficient/CDDsb or fcs/mag-speedbrake-pos-rad in the
property browser. when you deploy the speed brakes
Alex Romosan wrote:
Erik Hofman writes:
Looking at the code it looks like setting speed-break-pos-norm should be
the same as setting speed-break-pos-rad so the patch shouldn't have any
effect.
look at aero/coefficient/CDDsb or fcs/mag-speedbrake-pos-rad in the
property browser. when
Alex Romosan wrote:
Erik Hofman writes:
Looking at the code it looks like setting speed-break-pos-norm should be
the same as setting speed-break-pos-rad so the patch shouldn't have any
effect.
look at aero/coefficient/CDDsb or fcs/mag-speedbrake-pos-rad in the
property browser. when
i noticed that on the f16 the speedbrakes have no effect at all and i
managed to track it down to the fact that the various coefficients use
fcs/mag-speedbrake-pos-rad on input which never gets set anywhere (so
it is always 0).
digging through the cvs logs i found that in version 1.17 of f16.xml
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