Trident 2 Data needed

Chris Trott · Post by **Chris Trott** » 17 May 2006, 17:45

DispatchDragon wrote:No Chris I dont - I set up the flight plan for best mach for ALL in the information I load in and the nice little program firgures the TAS for me -
Once upon a time many many years ago I actually did the conversion with
an E6b but these days I dont need to - just as 100% of Major Carrier Dispatchers dont - anyway I can do a quick wag and give you what .88
comes out to still air and ISA

Leif

But you still get the TAS for your flightplan and other stuff that asks for TAS though right? That's the point I was trying to make.

Anyway, I'll let it rest, but I was trying to make the point that FlyNET isn't asking for a Mach Number, it's asking for a speed in Knots. If we need to convert it, fine, but a Mach Number is useless to me for the purposes of FlyNET.

Post by **Garry Russell** » 17 May 2006, 17:47

Garry

DispatchDragon · Post by **DispatchDragon** » 17 May 2006, 17:56

Mr Trott

You know I can sit here and attempt to explain things to you but you
dont seem to predisposed to listen. As Peter Mc was saying and I
believe if you asked Tonks (although that not fair because the RAF
does fly Managed IAS rather than Managed Mach when refueling)
and of course you could ask the 200 plus pilots in AAY (course none
of them know beter than you) The fly Managed Mach in cruise and
pay NO attention to either TAS or IAS. So flynets programming is flawed
and if you had anything to do with I can understand why. Please
just do as your have been requested and butt out - As you are an
Administrator for Flynet you will receive in due time the figures you
require to program these aircraft

Thank you from myself and the majority of the fourm for complying
with this request

Leif R Harding

Post by **DaveB** » 17 May 2006, 18:14

John,

Some activity on the post since I've been away.. flying the Trident2

Sorry.. still no MZFW figure but will continue hunting

For what it's worth.. the Eco Cruise chart and the model are not far off according to the hour or so I've been in the air. The test I ran is not conclusive but running as instructed at 300kias.. here is what you can expect from the model.. all at 1013mb ISA/No weather..
FL250/300kias/421tas/M.7
FL260/300kias/427tas/M.71
FL270/300kias/434tas/M.72
FL280/300kias/441tas/M.74
FL290/300kias/447tas/M.75
FL300/300kias/454tas/M.77
FL310/300kias/461tas/M.78
FL320/300kias/468tas/M.8
FL330/300kias/475tas/M.81
FL340/300kias/483tas/M.83
FL350/300kias/491tas/M.85
FL360/300kias/498tas/M.87
FL370/300kias/508tas/M.88

Coincidentally, I was heavy so the Eco Cruise of M.83 (the max from Chart6) is about the correct altitude for that speed. The idea being that as you get lighter, you slowly climb to maintain that mach number. Not sure whether that sort of thing would be allowed in this day and age mind you

Hope this is of use and for Chris.. TAS included

Regards

DaveB :tab:

Chris Trott · Post by **Chris Trott** » 17 May 2006, 20:00

Leif, I'm not going to quote the whole thing, but suffice it to say you are still failing to read my statements.

I don't care what the pilot will be doing. I don't care what speed the pilot flies the airplane. Neither does FlyNET. If you read *why* the number is there, it is not to tell the pilot how fast to fly. It is to allow the database to calculate the scheduled block time for the airplane selected when creating a new flight in the scheduling system.

This has absolutely nothing to do with what the pilot does when he books the flight. It only has to do with what shows on the screen for the scheduled departure and arrival time for any selected flight. How one flies their flight is up to them. Right now, there's no dicussion of penalties for being late, only discussions of bonuses for being early, so there really isn't any need for you or anyone else to be getting all bent out of shape over this. I keep trying to re-iterate what I've said from the beginning, but somewhere in the mix, not everything is being read and understood and thus we're getting to where we are.

Post by **RAF_Quantum** » 17 May 2006, 20:40

RAF_Quantum wrote:'lets put this to bed'.

PLEASE!

I've put a figure in, if it needs to be changed later it can be. So if parties wish to continue debating this feel free to do so in private.

Rgds

John

TobyV · Post by **TobyV** » 19 May 2006, 12:01

Sorry I havent been on this thread, tend to avoid VA's as its not my cup of tea. This is scanned from a BA Trident 2 Ops manual.

To get from Mach number to a speed (TAS presumably) at a given altitude you need an Intl (or American) Standard Atmosphere table. Once you have a TAS you need to find the online conversion thingy that estimates the difference between TAS and IAS at a given altitude. If you need to convert between different units, you can divide by 2.25 to get to mph from m/s and multiply by 1.15 to get from mph to kts. Hope that helps. Dont shoot the messenger

TobyV · Post by **TobyV** » 19 May 2006, 12:54

Further to my last post and in response to something Leif said. I would have thought, from a purely mathematical point of view, same Mach at same altitude should give the same TAS every time, however. ISA is defined with air temp at sea level being 15deg C or 288K IIRC. Thats not going to be true in LV, and since speed of sound is a function of temperature, it will be higher in LV with current temps than ISA standard I would have though. Factor in different people calculating it with varying rounding errors and source data to different levels of accuracy and that would to me explain the 5-10 knto differences I would think.

petermcleland · Post by **petermcleland** » 19 May 2006, 16:49

TobyVickers wrote:Further to my last post and in response to something Leif said. I would have thought, from a purely mathematical point of view, same Mach at same altitude should give the same TAS every time, however. ISA is defined with air temp at sea level being 15deg C or 288K IIRC. Thats not going to be true in LV, and since speed of sound is a function of temperature, it will be higher in LV with current temps than ISA standard I would have though. Factor in different people calculating it with varying rounding errors and source data to different levels of accuracy and that would to me explain the 5-10 knto differences I would think.

Yes Toby,

Speed of sound in dependant only on temperature not altitude. My Air Force E6-B used to have a window to work out the Mach Number but I can only find my little Civilian one and it doesn't do that :think: But obviously the TAS and IAS for a given Mach Number at a particular Altitude will vary from day to day in real life but for planning purposes I would have thought that ISA numbers would do.

TobyV · Post by **TobyV** » 19 May 2006, 17:34

Speed of sound is given by:

C=SQR(gamma*R*T)

Where gamma is the ratio of specific heats (which is about 1.4 for air), R is the gas constant (0.286 kJ/kg/K for air) and T is the absolute temperature in Kelvin.

Mach number is of course:

Ma = v/c where v is the velocity of the gas or object we are concerned with and c is the local speed of sound.