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XyZspineZyX
07-21-2003, 04:55 PM
hi All
Hi Oleg,

first of all, thanks for ure dedication and for the great sim you gave us
I have a little remark to do

On FW(sorry thats the plane I fly the most but its not a threat about the plane itself)
The vario needle seems verry slugish
for example , Flying gentlly in 20m/s descent , pull up gentelly max 2g's and set a 30deg pitch attitude, it takes a while before the needle just give you a positive climb
And I really think it should be more prompt!!
the same apply for the me262!

regards to all
:-)

XyZspineZyX
07-21-2003, 04:55 PM
hi All
Hi Oleg,

first of all, thanks for ure dedication and for the great sim you gave us
I have a little remark to do

On FW(sorry thats the plane I fly the most but its not a threat about the plane itself)
The vario needle seems verry slugish
for example , Flying gentlly in 20m/s descent , pull up gentelly max 2g's and set a 30deg pitch attitude, it takes a while before the needle just give you a positive climb
And I really think it should be more prompt!!
the same apply for the me262!

regards to all
:-)

XyZspineZyX
07-21-2003, 09:41 PM
Strictly speaking, it's not a variometer but a vertical speed indicator.

The difference? A VSI is much more sluggish than a vario.

XyZspineZyX
07-21-2003, 10:04 PM
not that much!

If we look at the vsi in the 262 or in the dora it looks like the static can is clogged somewhere and it gives very very slow changes
I wanted to say "anormally sluggish" rather than "more sluggish"

XyZspineZyX
07-21-2003, 11:30 PM
It seems you are correct:


From here: http://www.allstar.fiu.edu/aerojava/PSI.htm

"The vertical speed indicator has two separate functions. First, it operates as a trend instrument because it shows deviations from level flight before the altimeter registers any signs. There is no lag in this function. Second, it serves as a rate indicator. The calibrated leak prevents the pressure differential between the case and the bellows from equalizing immediately, causing an inherent lag. When the aircraft starts a climb or descent, it takes a few seconds for a pressure differential to develop between the same areas and indicate a rate of movement. The same is true when leveling off.

In summary, when the aircraft begins a climb or descent, the instrument immediately displays the change in pitch; however, the pilot must wait for six to nine seconds for an accurate indication of the rate of climb or descent. Nonetheless, the vertical speed indicator is valuable in sensing deviations from a selected altitude or establishing a constant rate of climb or descent."

XyZspineZyX
07-22-2003, 12:49 AM
TKX ,VSI should be more prompt in the trend and it s right that it takes some time to get the exact value
nowadays we also have IVSI wich are even more rapid and give more accurate values

my point is still the same, vsi in fb are way too sluggish

regards ;-)

XyZspineZyX
07-22-2003, 04:38 AM
FW was known to 'sink' in pullouts as Eric Brown had stated. You change pitch but the plane does not immediately change direction of flight. It is more on high wingload airplanes than others and not just the FW. Just watching the speedbar alt which has no lag, but plenty of slop, should confirm that you can level out or even pitch up a bit and still lose alt.


Neal

XyZspineZyX
07-22-2003, 08:27 AM
Wind_Master wrote:
- It seems you are correct:
-
-
- From here: <a
- href="http://www.allstar.fiu.edu/aerojava/PSI.htm"
- target=_blank>http://www.allstar.fiu.edu/aerojava/
- PSI.htm</a>
-
- "The vertical speed indicator has two separate
- functions. First, it operates as a trend instrument
- because it shows deviations from level flight before
- the altimeter registers any signs...."

- In summary, when the aircraft begins a climb or
- descent, the instrument immediately displays the
- change in pitch; however, the pilot must wait for
- six to nine seconds for an accurate indication of
- the rate of climb or descent.

To me, this was a new one. I must admit that the VSI is the instrument I use the least of the basic 6, but I've always found it to be only slow in reacting. I've definitely never seen it react before the altimeter. This is with old planes, though, from the 60s and 70s, but on the other hand, the planes we're discussing in this forum are far older than that.
_
/Bjorn.

XyZspineZyX
07-22-2003, 08:38 AM
swingman wrote:
-
- To me, this was a new one. I must admit that the VSI
- is the instrument I use the least of the basic 6,
- but I've always found it to be only slow in
- reacting.


Surprised me too. I knew a vario was faster than a VSI and was looking for some hard numbers to compare response times. This was the only thing I could find. Like you, I never paid a lot of attention to the VSI, mostly because of the lag.