Professional advise and some tech support

[simurq]

Hi there,

I am an avid FlightSim fan since 2003 so I do feel a bit uncomfortable among the real aviation pilots, so please excuse my "wannabe manners" if seem stupid... :)

Nevertheless, I'm learning to fly RealAir's excellent (to an extend a flightsimmer can guess) Beechcraft B60 Duke Turbine in FSX but trying to do "as real as it gets"... For this I need to make some ground prep guesstimations but am missing some performance charts since they're not shipped with the aircraft by default... Googling didn't yield anything positive yet... So, is it considered a breech of copyright if I request perf charts from aircraft manuals through this forum?

Also, is there a separate thread @ Pprune to ask some tech questions and professional advise from real pilots?

Thank you!

Rustam

[mutt]

Ask here in the Tech Forum, just be honest about why you want the answer...

Mutt

[simurq]

Hey Mutt,

Thank you for your prompt response!

Well, let me start then... Since I mostly fly VFR and prefer old-school navigation to autopilots and GPS, one of the confusing things about the ground prep routine is... TAS! I know what it is in theory - that it depends on pressure, temp, and winds; that it can be roughly derived from IAS by adding 2% to it per each 1,000ft, etc. But how can I know and use TAS before the actual flight, i.e. during the ground prep?!?

I would also like to know about the winds aloft considerations. Particularly, WHY winds are always given for altitudes of 3K, 6K, and 9K ft? And HOW to consider winds during ground prep if say I want to fly at an altitudes in-between these values (eg, 4500 ft, 7500 ft)? Shall I do rough interpolations?

That's all for now! Thank you very much in advance!!!

Rustam

[MarkerInbound]

In the aircraft manuals there will be cruise performance charts. I'm just going to make numbers for examples, I've never flown a Duke and haven't even seen one in years. You might have charts for running the engines at 50%, 65% and 75% of the engine's rated power. The charts will either be graphs or tables of numbers. The charts will tell you at a given altitude what MAP will give you the percentage power you are looking for, your TAS at that altitude and your fuel burn. Without the charts, unless someone can give you some ballpark numbers to work with, you can't get too far in you preflight planning.

[mutt]

In most aircraft you will find a performance manual, it should show the TAS for a specific altitude, otherwise you can use something simple like the Pilot Wizz APP for Iphone/Ipad, or on a website like Calculate your True Airspeed (TAS) [Aviation Rules of Thumb] - Flightsim Aviation Zone (http://www.flightsimaviation.com/rule-of-thumb/21_Calculate_your_True_Airspeed_TAS.html)

You said that you knew the theory, that it depends on pressure, temp, and winds..... Are you sure about this? Look it up again, especially the part about wind.

For the purposes of your flt sim, interpolate the wind, its up to you to decide on the number of interpolations that you want to do.

Good Luck

Mutt

[Da-20 monkey]

In fs 2004 and fsx you can get the current wind/ velocity with pressing shift+ z or shift + y. MSFS does not interpolate the wind and this is notable when you go through another wind layer.

Note that TAS is true airspeed, and is equal to groundspeed without wind.

To find groundspeed with wind, TAS+ or - 1/3 of wind speed if it is from 60 to 90 degrees, 2/3 for 30 to 60 degrees and full for if the wind comes from 30 degrees to your heading. If the wind is from exactly 30 or 60 degrees to your hdg, resp. take 50 and 75 % of wind speed.


Do you have rudder pedals?

Also, note that terrain in MSFS does not resemble the real world a lot, you can get aftermarket terrain but you need a RollsRoyce PC to run it.

[Checkboard]

The True Airspeed an aircraft achieves is a function of the power you set and the drag. The power setting you use is based on how much money you have - 55% if you can't stand the fuel bills (the Duke is a thirsty aircraft), 65% as a "standard" - 75% for "damn the bills, full speed ahead!"

For piston aircraft, pilots simply memorise the speed their aircraft "trues out" at. For a Duke at 65%, you are looking at 48 US gph (180 litres per hour) and 210 knots TAS @ FL200 or so. If you fly lower, the drag goes up in the thicker air, and the aircraft will thus lose about two knots per thousand feet (so at 10,000' you will be looking at about 190 knots, and the same fuel flow).

So - look at your wind forecast, choose the best level for wind (least headwind/most tailwind) work out your TAS at that level, add/subtract the tail/head wind to get the ground speed. Measure the distance you want to fly, divide that by your ground speed to get the time (in hours) and multiply that time by the fuel flow above to get the fuel required. Throw on a bit extra fuel, so your Mum won't worry about you not coming back, and Bob's your uncle. ;)