You may have noticed that the final beta for 7.10 was around beta FIFTY! This is because there were about FORTY non-public Betas all shared with only one customer: Pro-Flight.
Pro-Flight has obtained FAA-certification for recurrency flight-training in the Cessna Conquest turboprop,
and I have been working rapidly with them over the last few weeks getting X-Plane tweaked to FAA-approval level
on the autopilot and engine-management systems.
This has resulted in the turboprop engine, electrical, and autopilot systems being completely overhauled, and
we have even made the networking a good bit more robust as well (remember, the FAA-certified version of X-Plane
actually involves 6 copies of X-Plane networked together)

OK, so here is the new engine stuff:

There are now two types of turboprop engines: Free-Turbine and Fixed Shaft.
Here is how they work, in reality (and in X-Plane)

The Fixed-Shaft turboprop engine is pretty simple: a turbine spins at insane RPM as fuel is burned in front of it,
and that turbine is geared down (a LOT) and a transmission goes right from the turbine to the prop.
This means the prop is hard-locked to the turbine. Whatever percentage of maximum RPM the prop turns, the N1 turns as well.
A perfect lock between prop and turbine.
This type of engine is the most efficient since there are no losses in the transmission from the turbine to the prop.
You get the efficiency of highly compressed, enclosed combustion, and since this turbine drives a prop, you get the high
efficiency of a porp as well (more efficient than a jet since the prop takes a bigger bite of air than a jet, and only accelerates
that air a little, unlike a jet, which grabs only a little bit of air and accelerates it a lot.
You get the most propulsive efficiency by grabbing a LOT of air and pushing it back a LITTLE.
This is what props do (not jets) and is why props ar emore efficent.. they waste less energy shoving air back really fast.
So, the fixed-shaft turboprop engine with its big prop, enclosed conmbustion, and (nearly) zero-loss transmission is a shoe-in for the most efficient engine.
It is what the GARRET engines use in the powerful, efficient MU-2 and Cessna 441.
Unlike the Cessann Citation Biz-Jet costing much more, the Cessna 441 turboprop can fly UNREFUELED from LA to NYC.
The low-end Citation has to stop for fuel on the trip, making it considerably SLOWER than the turboprop going cross-nation.
Cessna has stopped building the mighty 441 turboprop, but does a brisk trade in the less-efficient, slower Citations, at a higher profit per jet.
So why has Cessna stopped making the lower-profit-margin 441, which OUTPERFORMS the higher-profit-margin Citation?
Uhhh... maybe I just answered my own question.

The second turboprop engine type simulated is the Free-Turbine type, demonstrated in the velnerable Pratt & Whitney PT-6.
This engine works differently than the Fixed-Shaft Garret.
This engine has a compressor and turbine THAT ARE NOT EVEN CONNECTED TO THE PROP!
Instead, the compressor just blows air over a turbine that is connected to the prop!
This air blowing over the turbine spins the prop.
Since there is no direct connection between the compressor (N1) and the prop, you can start a Pratt & Whitney engine
while holding the prop still in your hands.
The compressor spins right up and screams merrily along, running, while you hold the prop motionless.
My advice to you: If you let the prop go to let it start spinning, DON'T go back to grab it again.
The PT-6's lose efficiency in this "air clutch" arrangement, though, so they burn fuel faster then the Garrets.
Most people still like them though because they ALWAYS start, they ALWAYS run, they are EASY to start and fly,
and you simply don't get any headaches using them
After all, they were designed to pump oil down pipelines from Alaska, where they would run for weeks at a time
without anyone ever supervising or maintaining them.

Anyway, both engine types are now simualted, each with their own quirks intact. Check out the turboprop engine options
in Plane-Maker to select the engine that is right for your airplane.

Another improvement for FAA-certification is the electrical system. Now, we have generators (which CHARGE the batter from the engine)
as well as INVERTERS (which convert the DC juice from the battery into AC for certain flight instruments).
So, if you want your ADF, RMI, autopilot, and electric artificial horizon to work, turn on the inverters if your plane has the switches!
While I was at it, I added gyro-modelling (both vacuum and electric) for the artificial horizon and DG/HSI/ADF/RMI.
Gyros not only spin down correctly, but spin up over time as well.
Kill your vacuum system and your vacuum artificial horizon and DG will gradually die out.
Leave off your generators (if you have the switches on the panel) and watch what happens to your electric artificail horizon as your batteries
gradually die... yep! As the votlage slowly wanes, so does your electric artificial horizon (becoming sluggish and finally stopping) and any
other electric instruments (HSI card, for example)
When the votlage finally gets down to zero.. lights out!
If you have the "flagged" artificial horizon, then a little red failure flag will copme out of hiding and display itself when the voltage gets too low.

Another improvement for FAA-certification is the autopilot. Airspeed, autothrottle, VVI, and headng modes work as before, but here are some differences:
When you are coming in at an ILS, you will push the HNAV and VNAV buttons and they will lite up in RED, meaning that they are WAITING TO CAPTURE.
You can be in altitude hold mode, VVI hold mode, heading hold mode, or just hand-flying.
It makes no difference.
All that matters is that those HNAV AND VNAV modes are waiting for their first sniff of localizer and glideslope, and as soon as they get it
(the localizer and glideslope needles come in from the edge) the autopilto snatches control away from the previous mdoe and follows the ILS home.
This is the way it works in the real plane, and the way it works in X-Plane.
Also, the autopilot is just plain better at tracking.
Also, we have added a "level-change" function to the autopilot as used by the airliners.
Pro-Flight did not need this, but while I was overhauling the autopilot I decided to be thorough and get it in there.
Here's how it works: you are established on speed and altitude at cruise... dial in a new altitude and hit the level-change auopilot button.
The autopilot will throw in or take out a bit of thrrottle and pitch the nose to hold a constant airspeed, resultig in a climb or descent at
a constant airspeed until you get to the new altitude. This is how the airliners do it.
Also we added another new autopilot function: Pitch Sync.
Hold this button to disengage all autopilot pitch functions except glideslope capture.
Then, when you release the button, the autopilot holds your pitch attitude until you hit the localzier, some other autopilot mode, or the ground, whichever comes first.
Control of pitch sync is toggled by some new autopilot buttons, or more, realisitcally, vis a joystick button now in the joystick button list.

Another thing done for Pro-Flight is improvement of the Instructor Operators Station (or IOS).
Hook up 2 copies of X-Plane on 2 computers by an ethernet, and specify one as the pilot's machine and one as the IOS
in the Settings:Data & Net:Internet Settings screen.
You will notice the instructors station has all the other little planes buzzing busily around (if you have other planes
set in the rendering options screen) and you can place them at will, like an Air Traffic Controller with Teleport powers.
You can also enter a local airport ID to place the pilot on takeoff or final approach to any nearby airport, as well
as see that airport's extended centerline for vectoring him around.

OK, so that is the powerful new stuff brought to us from Pro-Flight and the FAA-certified world of flight training.
Here is the fun-n-easy stuff we are used to seeing with each new release:

Other Flight-Model:

New Artificial Stability System: Set the transition speeds for each axis...
this is good for helos to keep pitch-tracking at ALL speeds, but sideslip-tracking only at at HIGH speed.

Hook up ALL the wings you want in the entire sim to make fewer bigger, curvier wings and the math will be right.
You used to be restricted to 3 wings to do this.

New special control option: spoiler cutout speed, as used on some craft.

Autopilot algorythm overhaul: When you turn on the autopilot you can still enter aileron (and, in helos, anti-torque) deflections but with only 20% authority,
to simulate over-riding the servo. In pitch, the autopilot uses trim not yoke deflections, so you still have full yoke deflection in pitch since you are not
working against a servo in that case.
Also, we now have a smoother autopilot engage, and the auto-throttle does not engage the afterburner.

Better aspect-ratio calculation... we now include the entire wing (even the part inside the fuselage that you may have neglected in Plane-Maker) to get the right AR in all cases.

Control effectiveness and flaps are now much more realistic.
They now map to real control effectiveness more accurately across a range of deflections,
and more completely consider finite-wing effects to have different effectiveness on different wings!

Visuals:

Better sun glare effects... try flying looking right into the sun!

New object option Level of Detail. Use a lower-res version of your object farther away to speed framerate.
See the KSBD exampl in the custom scenery folder for an example.

New object attribute: no depth-test. good for making markings on the pavement around your custom objects (like for parking lots, tarmecs, etc)
see the custom object KSBD example in the custom scenery folder for an example.

New Calvert approach lites! Set them in World-Maker.

New apt.dat format, now with rotating beacon and windsock locations, and beacon flashing correctly for airport, military airport, heliport, and seaport.
Also, new apt.dat windsocks are controllable as lit up or not!

Even the turboprops smoke a little.

Sun glare is now right at all angles, not just front view.

Speed Increase:

Faster load times... by about 25% if you had "draw fixes" on in 7.00.


New Interface:

Pop-up menus! These are useful everywhere, especially to speed the file-selection to open airplanes and stuff.
Check out the wings screens in Plane-Maker.. you can see the craft while editing it.

Radio buttons used whenever you can make one selection only from a list.

New icons for OS-X and Windows,thanks to David Hossack!

General Features:

Place OTHER AIRCRAFT on the map now in any of the maps... cool to set up formation flights, traffic to avoid, etc.

New autobrake option: RTO... this is rejected takeoff, and applies max brakes if the power is brought down to idle from a hight setting.

New failure option: Broken drive shaft... the engine over-revs while the prop winds down... cool!

New runway option: shoulders. Done in World-Maker, per runway.

Bombs leave "crater markers" and puff smoke so you can see where they hit.

Button to drop the drop the drop tanks, selectable in Plane-Maker.

Random aircraft on the ground around at the larger airports, selectable in rendering options screen.

Sound volume slider in Sound window... good for apps like squawkbox (incredible atc with real controllers over the net!).

Radios tune by 25 increments now, allowing access to more frequencies.

Check out the change environement properties in the special menu... set up any air and gravity you like!

Gear cycle time randomization... much better to see the gear come up at slightly different times.

Timezone offset in the Time window... enter this if X-Plane is not quite right about your timezone and daylight savings time.

Multiple ramp-start locations... set them up in World-Maker and start at them in the Location menu in X-Plane.

Check out the failure screen, instruments section.:
we now have failures for nav 1, nav 2, gps, adf, dme, marker beacons, localizer, and glideslope systems. another faa-related improvement.

Turning off the battery does not kill the elec system if you still have any engines running... the generator or alternator keeps the system running.
Various electrical systems only run down the batery if the battery is turned on, and the inverter draw some power as well.

General Refinements:

Winch is slower, as in reality.
Powerlines easier to see in World-Maker.
World-Maker: select seaport, heliport, or airport type.
Tip-rockets are operated by fadec to seek the max engine rpm set in Plane-Maker.
Mouse hides if inactive for a few moments... can be kind of convenient.
Bumpier runways... more realistic for plenty of cases I have seen!

People that have only 2 tex units (NVidia Geforce-4-mx) can now get landing lites as night...
they still pay a pennance though for the cheap card! They will NOT get any skidmarks at night on the runways at nite!


New more powerful custom needle options.
See the udp reference.html guide

keys: ' is now autopilot hold alt until GS intercept, not fadec. CONTROL-' is fadec.

New data output: more autopilot detail

Batch update of airfoils in Airfoil-Maker updates the foils in your aircraft folder as well!
Now it is a COMPLETE update

ITT now reflects how long the engine has been running in the temperature indications.

Tower viewpoint height from World-Maker is used to determine the height of the tower object as well.
Plane-Maker holds the size of the lights constant regardless of zoom.
Weapons can save without using "save as" command.

Bug Fixes/Robustness improvements:

No more small temperature and presure variations as you fly unless called for by the real-weather.
Save airports in World-Maker will not overflow the airport file.
Tires show right width in X-Plane.
Esoteric rudder with aileron option in Plane-Maker now INCREASES EXISTING RUDDER INPUT, rather than replacing it.
Helo tail-rotor tachs are scaled correctly.
Tower height as set in world-maker now in feet, as labelled in World-Maker.
no more paved seaports
no more string too long error when dealing with many files
FMS auto-advance
carrier ILS oeprtive
data output to net operative ALL the time
no more runway distance remaining signs in the other runways
weather synced correctly between weather radar and real condition
groundspeed EFIS element is groundspeed now, not airspeed
icing state and asi indications preserved on the replay