From: prang@ssc-vax.boeing.com (Ron Wanttaja)
Newsgroups: rec.aviation
Subject: PC, Flight Simulators, and What General Aviation Really Needs
Keywords: Blast from the Past
Date: 26 Aug 92 01:58:42 GMT
Organization: Boeing Defense and Space Group, Seattle WA

Robert Dorsett had a copy of an old post of mine squirrelled away... one in
which I stated my opinions on PC-based flight simulators and such *five
years* ago.

Rereading it was like looking at old photos of yourself from the '60s...
tie-dyed clothing, love beads, and long hair ('course, in my case, it was a
CAP uniform, a crew cut, and an NRA rifle medal, but digress).  It is definitely
dated, to the point where, it's at times painful for me to read.  But I 
still agree with it; Robert thought it might have relevance with some 
discussions going on right not that I'm not able to see because our .Rec 
feed is out again. 

So here it is:

-------------------

From: wanttaja@ssc-vax.UUCP (Ronald J Wanttaja)
Subiect: PCs, Flight Simulators, and what General Aviation really needs
Date: 26 Feb 87 01:42:17 GMT
Organization: Boeing Aerospace Corp., Seattle WA
Keywords: Ron Rants and Raves again... Hit 'n', quick!

ah, flight simulators... one of my favorite topics.

I have done a lot of thinking on the subject of flight simulators for home
computers. This massive tome is divided into three parts: l) my
experience in microcomputer flight simulation; 2) the problems of
nicrocomputer flight simulation, and 3) the simulator General Aviation
should be asking for.

Those of you with Commodore machines might look in your old
files and see if you have a copy of Academy Software's "IFR (Flight
Simulator)." It was one of the first realistic simulators for the C-64,
and probably the only realistic simulator for the Vic, PLUS/4, and C-16.

I am a bit biased, of course, 'cause I wrote the program. This month
is the fourth anniversary of version 1.0.  IFR, as the name implies, was an
instruments-only program, and was my first machine-language effort.  As a
natter of fact, it wasn't completely ML, either. IFR was an attempt to
distill the flying experience... to cram everything that would occur on a
four-hour flight into forty minutes.  Navigation was entirely by chart
and instrument reference. There was terrain of varying height to fly
around. Tanks had to be switched. Airspeed limits had to be obeyed. The
plane would spin if stalled.

IFR was reasonably popular in its day (Toys-R-Us sold over 25,000
copies), but the C-64 version was trounced when Sublogic finally brought
out Flight Simulator II.  IFR hit the market at nearly exactly the right
time- Sublogic advertised FSII for the 64 for six months before it finally
was released, and IFR filled the gap.

What is necessary for a realistic flight simulator?

1.  A fast update of aircraft attitude and attitude display. IFR updated
attitude and the instruments 4 times a second. FSII for the C-64 updates
the attitude display once a second, but calculates it much faster. The
Microsoft Flight Simulator (written by Sublogic) updates about 5-10 times
a second.

One expert I talked to said the minimum update rate for a realistic
simulation was 30 hertz. Personally, I'd say 10 was an acceptable minimum.
Anything slower means the plane acts sluggish. Sublogic's solution was to
have additive control input between updates... hold the stick to the right,
and more and more aileron is added while the screen remains unchanged.
Then, when screen update time comes, POW! The aircraft is now rolled 60
degrees, and the display freezes until the next update. This can be
likened to flying an airplane by closing your eyes, moving the controls,
opening Your eyes for a moment, then closing them and moving the controls
again. While this is little problem on the IBM vrsion, the slow update
rate on the 64 can really be disconcerting. The slower the update rate,
the less the pilot can intuitivelY determine axis rates. If one is looing
for a truly realistic full-function flight simulator, stick with the ones
for the faster machines.  Sublogic's IBM versions aren't too bad (although
I'd like to try one with a joystick), "Radar Raiders" on the Amiga
is impressive, and I am eager to try out some simulator on the Mac.

2.  The simulation should have realistic controls and responses.  An
Atari-style stick is at a disadvantage here.  My solution in IFR was to have
two control rates... a faster rate was available when the fire button
was pushed.  But the attitude would remain fixed (unless a stall occured) until
commanded to change by the stick.  Sort of like flying through an autopilot.

Sublogic's control input routine did make variable rates available using
the Atari joystick, once the operator learned how to control it.  As far as
I'm concerned, keyboard control is a laugh.  I still remember hearing one kid
say "Taking off is easy.  All you have to do is go to full power, wait
until speed is 60, then press the cursor down key seven times."  I've had a 
little experience with mouse control.  It's not TOO bad, except
for having to reposition the mouse occasionally.  I'd replace the mouse 
with an analog stick.

The deciding factor is this: using only the outside view (or attitude
indicator) can the operator easily ssume any desired attitude?  Can he/she
enter a bank, and easily stop it at a given angle?  An analog stick with
a fast attitude display update is the ideal solution.

3.  If a visual display is included, it must include depth cues or it is
just a pretty picture.  Detail can be variable, depending upon the aircraft
simulated.  An airliner, for instance, sits high enough off the runway to
reduce the need for extrememly detailed cues.  But a BD-5 simulation
better show the cracks in the runway.

Shoot a quick imaginary landing.  Note the way the trees at the far end
of the runway appear to rise and cut out the horizon.  Note the parallax
change in the hangars.  Note how the little details become sharper and more
detailed as you get closer to the ground.  See how the runway becomes a 
blur as you pull into the flare.

A visual simulator that can't show all these things... at an update rate of 
10 hertz... can't really be said to simulate a visual landing.  If you
don't receive enough visual cues to judge flare height, how are you going 
to flare?  IFR, since it had no pretense at an outside view, had
to have a digital display of the last two digits of the altitude to allow
judging of the flare height - not really realistic.

4.  The ultimate test of a simulator is this:  Hand a pilot the stick, show
him how to work the throttle, and turn 'em loose.  Warn them of particular
handling problems if necessary.  IFR, for instance, had a tendency to
overrotate.

During 1983, I had a demo booth at a local large computer show, and ran 
many people through IFR, pilots and non-pilots.  One lesson was
obvious: pilots DO NOT like crashing a simulator.  It's hard on the ego,
and they blame the program.  And they're right... after all, they have 
never crashed an airplane.  Actaully, I had few crash cases.  In a couple
instances, I had professional pilots take off, fly a pattern, acquire the
ILS, and land successfully with very little intervention from me.  Most of
my nice "fan mail" came from pilots... including a couple of 747 captains.

-------

What kind of simulator does General Aviation need?  In my opinion, GA needs
procedure simulators, instead of highly accurate, expensive visual/
instrument simulators.  One of the prime things the airlines and the 
military use simulators for is to simulate emergencies that would be
difficult or dangerous to perform in the actual airplane.

Remember, we aren't talking about exact fidelity to a particular aircraft,
so processing load goes down.  We need an approximate cockpit with
all the controls and instruments close to hand.  Basic instruments, no ILS,
no radio or tranponders (or just dummy units)  We aren't teaching flying, 
we're teaching procedures, so takeoff and landing visuals don't have to
have all the depth cues.  Stick the victim in the seat, have him/her take
off, then sock 'em with one emergency after another.  Do it until reaction
is completely automatic.

What kind of emergencies could be simulated?  Well, the engine oil pressure
could quietly go to zero.  Carb ice could be simulated.  Partial engine
failures.  Slowly increasing temperatures.  Engine failure procedures.  180
degree turns after inadvertent cloud entry.  Night forced landings.
Electrical failure.  Pitot icing.  Clogged static system.  Incorporate some
displayed traffic and see if he/she knows the right-of-way rules.  Even 
tower light signals, depending upon the display capability.

This could be handled with a Commodore 128/Commodore 64 duo- one computer
dedicated to drawing the view, the other side calculating and driving any
displayed or separate instrument.  Position, altitude, and attitude data
could be passed to the view computer via the 18 bits of parallel I/O the 
machines have available.  Use one monitor to show view, another to show
instruments, or use simple meters for the engine instruments and split-
screen the flight instruments and the view.  Analog joystick of course, even a 
full-size yoke.  Analog throttle, and discrete switches instead of
keyboard control.

Market?  Fairly small actually.  I can't see too many FBOs buying them for
their students, and I can't see too many Private types volunteering and
paying for a nice abusing session in a procedures trainer.  *I* think it
would be rather fun, though, and really would like the chance for some
intensive problem recognition/response practice without throwing a $40,000
lightplane all over the sky.

If I wasn't so busy right now building Nieuports (uhh, and working for 
Boeing, too :-)) I'd go ahead and build one anyway.  Ah, well,
at least it's off my chest...

                                      
"Now, Ron, if you'd been watching your
 gauges, you would have noticed you'd run
 out of fuel.  Put another quarter in,
 and let's start again..."                                                                            

                                          Ron Wanttaja
					  prang@ssc-bee
					  ...rutgers!uw-beaver!ssc-bee!prang
                                          prang@ssc-bee.boeing.com
Newsgroups: rec.aviation