Archived from groups: alt.games.microsoft.flight-sim (
More info?)
Your observation is correct. T/O flaps setting is generally lower than
landing flaps. The reason for that is obvious:
For T/O the goal is to have the best balance between additional lift by
flaps and as low drag as possible. T/O speeds are therefore in the range of
1.2 * Vstall as during initial climb out some additional lift force will be
available by the vertical part of the thrust vector.
For landing it's the other ways round. You need as much lift as possible
(actually: as low speed as possible) and also additional drag. But as the
thrust vector usually points more or less horizontally there's no additional
lift force from the engines. So approach speeds are usually in the range of
1.3 * Vstall.
Now for flap setting and retraction speeds things are going to be a bit too
complex to be answered in a few lines. The placarded limit speeds are so
called "hard limits" (at least IRL...) and lead to some unwanted inspection
and maintenance time when exceeded. So the first thing is to make sure that
flaps are ALWAYS retracted before reaching those speeds and never extended
above those.
Unfortunately the information on FS' default jets is quite rudimentary but
still a few important speeds are mentioned in the kneeboard checklist. So
take the relevant V2 speed (for the appropriate T/O flap setting which is
e.g. for B737 5° flaps) and do the initial climb out with V2+10 KTS to 1500
ft AGL (this usually being a limit set by company operational standards).
Expect a pitch angle of 15-20°! After that start accelerating (pitch to
approx. 10°) and retract the flaps stepwise. IRL there would be a MINIMUM
speed for each flap step. But again for the B737 take 15 KTS increments for
each step. So in this example at V2+15 retract to flaps 2, at V2+30 retract
to flaps 1, at V2+45 retract to flaps 0.
Now again things are getting a bit complicated ;-) The retraction speed for
flaps 0 is NOT your minimum speed for flaps 0 (clean configuration)!! Your
minimum speed for that would be Vstall clean * 1.5. For a medium weight B737
take 210 KTS, that will be ok. So make sure that you don't reduce power
below climb thrust before reaching 210 KTS!
Now going for approach and landing. For this flight segment usually there
are tables of so called "reference speeds" for clean configuration and each
step of flap setting. They are definend by the A/C aerodynamical
characteristics and usually based on Vstall * 1.3. A few Vref are also
available in the kneeboard checklist. So for landing at full flaps use the
appropriate Vref +5 KTS. (for gusts and/or windshears add 5,10 or 15 KTS,
but never more that Vref+20 and observe the max. flap speed at high landing
weights......things may again become a bit tricky there...)
For intermediate flap settings again IRL there would be a minimum speed
published for each flap setting. As long as manoeuvring flaps are used (in
the B737 up to and including flaps 20) those speeds would be based on Vstall
*1.5 whereas for final approach (usually two flaps setting are used, 25° and
30°, the latter being standard) Vref+5 is applicable.
So again for a medium weight B737 take the following min. speeds.
Clean 210KTS
Flaps 1+2° 195 KTS
Flaps 5° 185 KTS
Flaps 10° 175 KTS
Flaps 15° 170 KTS
Flaps 20° 160 KTS
You might see that it's getting a bit lengthy for even a very rough
explanation of the whole "speed thing" when it comes to heavy iron. But why
should I be able to explain it in a few lines when IRL you have to study it
in a performance course(among other things of course) in three weeks? ;-)))
And yet another hint: Try googling for speed tables of your desired A/C. I'm
sure there are some available. They will keep you quite busy for some
time...
)
--
Oskar Wagner
(retired Captain)
Remember, in the great scheme of things, we're all small potatoes....
<ppp@ppp.com> schrieb im Newsbeitrag
news:iaubi1pgvout7fsev011g8p5umusufendo@4ax.com...
> Since I was last here, months back, I've been doing quite a bit of
> 'real world' flying.. (Funny how the ground from 38000' often looks a
> lot less authentic than it does in FS9+mesh/lc..!).
>
> I notice, when sat over the wing (why do they ALWAYS seem to put me
> there so as I can't see the ground properly?!), that at take-off and
> landing the degree of flaps the pilots choose looks, as far as I can
> tell, to be pretty variable from flight to flight.
>
> Back in FS9, if I take off with 10 degs of flaps, say, at what stage
> exactly should I be reducing to 5, 2, 1, none. And similarly during
> approach & landing - at what point do I add flaps at
> 1,2,5,10,15,20,25,30 degs? The max flap/airspeed indications shown in
> some cockpits seem only a very rough guide. If I am at 160KIAS, for
> instance, MUST I ineviatbly have 30degs of flaps? FS9 jets seem to fly
> fine at that speed with no flaps at all. Anyone know how accurately
> the FS9 flaps mimic real thing?
>
> (Asked to go into the cockpit to see for myself last week - but, as
> expected, they said 'no'. Understandable, but SUCH a shame).
>
> Any wisdom gladly read!
>
> Thanks,
>
> Martin
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