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Home > Archive > Flight simulator > February 2006 > Flight Planning and TAS
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Flight Planning and TAS
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| I spend quite a lot of time flying the FSD Lockheed Constellation - it looks
nice and there's rather more to do than just flick on the FMC or GPS and sit
back - and I also like to try and plan from A to B using real weather and
air routes.
During the planning stage of a flight there comes a point where I have to
decide on how much fuel I'm going to need to get from A to B plus reserve,
holding, diversion and "a little bit for my mother" fuel. The problem that
I have is in establishing what my TAS for a given cruise IAS (and height) is
going to be so that I can make an accurate-ish calculation of duration (and
therefore fuel required) and also drift (for those nasty dead-reckoning
black holes that appear particularly over large expanses of water!). From
experience I can usually make a guess and a rough - often very rough -
estimate of how long the flight will take, but it really is just a guess.
So (Oskar? Beech? Anyone?) is there a rule of thumb/accurate
method/downloadable table for IAS-TAS?
Thanks,
Steve
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| john hawkins 2006-02-26, 7:44 pm |
| IRL, the aircraft handbook has tables for fuel consumption &. TAS, for
various gross weights, percent power and altitudes. In the case of the
Connie it would be quite thick and probably include various formulas as
well.
I would assume that the Connie's description that came with your model would
include at least some of the data.
You could, of course, be your own test pilot and develop your own set of
tables. (set up steady flight at specific RPMs and Manifold pressure and
altitude with no wind and standard temperature, record the indicated
airspeed. After you have a nice set of data ,convert the indicated to true
airspeed.
"Steve" <steve@DELETEMEFIRSTzord.co.uk> wrote in message
news:dtms04$gmb$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com...
quote:
> I spend quite a lot of time flying the FSD Lockheed Constellation - it
looks
quote:
> nice and there's rather more to do than just flick on the FMC or GPS and
sit
quote:
> back - and I also like to try and plan from A to B using real weather and
> air routes.
>
> During the planning stage of a flight there comes a point where I have to
> decide on how much fuel I'm going to need to get from A to B plus reserve,
> holding, diversion and "a little bit for my mother" fuel. The problem
that
quote:
> I have is in establishing what my TAS for a given cruise IAS (and height)
is
quote:
> going to be so that I can make an accurate-ish calculation of duration
(and
quote:
> therefore fuel required) and also drift (for those nasty dead-reckoning
> black holes that appear particularly over large expanses of water!). From
> experience I can usually make a guess and a rough - often very rough -
> estimate of how long the flight will take, but it really is just a guess.
>
> So (Oskar? Beech? Anyone?) is there a rule of thumb/accurate
> method/downloadable table for IAS-TAS?
>
> Thanks,
> Steve
>
>
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| "john hawkins" <john_hawkins@earthlink.net> wrote in message
news:kRCLf.2555$F56.2527@newsread3.news.atl.earthlink.net...
quote:
> IRL, the aircraft handbook has tables for fuel consumption &. TAS, for
> various gross weights, percent power and altitudes. In the case of the
> Connie it would be quite thick and probably include various formulas as
> well.
>
> I would assume that the Connie's description that came with your model
would
quote:
> include at least some of the data.
Yes, some of the data. However, that data is limited and gives power
settings for various cruise regimes and a rough guide to expected IAS. IAS
doesn't help when it comes to determining TAS from which I can then
calculate ground speed and drift taking into consideration wind effect.
An simple example might illustrate the problem better......
From actual experience with the model, 31" MAP with 2000 RPM yields roughly
190 kts IAS at FL210 (at getting on for max AUW). I'm heading west (Hdg
270) and have made the error of planting myself in a wind layer where the
wind is westerly blowing at 95 kts (wind 270/90). If TAS was the same as
IAS then I'd be travelling west over the ground at half the speed I would
achieve in still air so I'd have to calculate fuel to last at least twice as
long. However, my ground speed isn't 95 kts (190-95) towards the west, it's
rather more than that because my TAS is rather higher than the 190
indicated. The question is, how much higher and how do I work out how much
more?
It gets even more complicated if I decide to climb or descend and the TAS
has then either increased or decreased and my resulting ground speed then
also increases or decreases. I need to know the TAS (and can thus calculate
the ground speed) to work out the new leg times and also the drift offset if
the wind then changes direction to 30° off the nose. DR at its best!! :-)
quote:
>
> You could, of course, be your own test pilot and develop your own set of
> tables. (set up steady flight at specific RPMs and Manifold pressure and
> altitude with no wind and standard temperature, record the indicated
> airspeed. After you have a nice set of data ,convert the indicated to true
> airspeed.
>
I already know what IAS I'm achieving (and what the limited documentation
says I'll achieve) with various MAP and RPM settings so.........
Convert, yes. How?
Steve
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| john h 2006-02-26, 7:45 pm |
| Sorry I did not understand your problem.
use the calculator at http://www.csgnetwork.com/tasinfocalc.html
Yes you do have a lot of work to do in preflight.
IRL ( light aircraft) I do the following
plan the flight using a table(HowGozIt) as follows
Leg distance True Course ETE ETA ATA
depart - Fix 1 40NM 345 30 min 12:30
fix 1 - fix2 200Nm 350 1H20min 13:50
etc
etc
Fix n - arrival
ETE = Estimated Time Enroute
ETA = estimated Time of Arrival
ATA = actual time of arrival Note this when you get there
In planning
remember that" True Virgins Make Dull Companions" to convert
True Course + Magnetic Variation + Compass Deviation = Compass course
For Estimated Time enroute
include estimated wind correction + TAS to compute Estimated Time Enroute
initial climb
compute time to climb use Approx TAS for your climb IAS. and average Winds
Aloft data to compute distance traveled
The big thing to remember is that ALL The preflight values are estimates.
Once you start getting actual data, you recompute all your estimates Esp
your fuel remaining as you are well aware you may have to change your
destination to refuel if conditions warrant.
As you arrive over the Fixes on your flight plan,. note the time and
recompute your speed over the ground. to use for the next estimates.
Hope this does not insult your existing knowledge.
"Steve" <steve@DELETEMEFIRSTzord.co.uk> wrote in message
news:dtnkhk$hcr$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com...
quote:
> "john hawkins" <john_hawkins@earthlink.net> wrote in message
> news:kRCLf.2555$F56.2527@newsread3.news.atl.earthlink.net...
> would
>
>
> Yes, some of the data. However, that data is limited and gives power
> settings for various cruise regimes and a rough guide to expected IAS.
IAS
quote:
> doesn't help when it comes to determining TAS from which I can then
> calculate ground speed and drift taking into consideration wind effect.
>
> An simple example might illustrate the problem better......
> From actual experience with the model, 31" MAP with 2000 RPM yields
roughly
quote:
> 190 kts IAS at FL210 (at getting on for max AUW). I'm heading west (Hdg
> 270) and have made the error of planting myself in a wind layer where the
> wind is westerly blowing at 95 kts (wind 270/90). If TAS was the same as
> IAS then I'd be travelling west over the ground at half the speed I would
> achieve in still air so I'd have to calculate fuel to last at least twice
as
quote:
> long. However, my ground speed isn't 95 kts (190-95) towards the west,
it's
quote:
> rather more than that because my TAS is rather higher than the 190
> indicated. The question is, how much higher and how do I work out how
much
quote:
> more?
>
> It gets even more complicated if I decide to climb or descend and the TAS
> has then either increased or decreased and my resulting ground speed then
> also increases or decreases. I need to know the TAS (and can thus
calculate
quote:
> the ground speed) to work out the new leg times and also the drift offset
if
quote:
> the wind then changes direction to 30° off the nose. DR at its best!!
:-)
quote:
>
true[vbcol=seagreen]
>
> I already know what IAS I'm achieving (and what the limited documentation
> says I'll achieve) with various MAP and RPM settings so.........
> Convert, yes. How?
>
> Steve
>
>
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| Thanks - exactly what I needed.
Steve
"john h" <jf)hawk.nospam@yahoo.com> wrote in message
news:es7Mf.3718$S25.1717@newsread1.news.atl.earthlink.net...
quote:
> Sorry I did not understand your problem.
> use the calculator at http://www.csgnetwork.com/tasinfocalc.html
>
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