Citation :
So, you have not heard from me in a long time.
Why?
It means I have either gotten lazy and slacked off, or been deep into
coding the hard new stuff for 8.50.
So which is it?
Read on!
X-Plane 8.50:
This release is all about shortening and tightening and re-organizing
the code, increasing the frame-rate, increasing the power and
flexibility and realism of the sim, and integrating the major,
structural changes to carry X-Plane forwards with the really big new
features.
Here's what's done for 8.50 so far (I expect beta in about a week or
two)
Huge New Features:
This one is HUGE: ALL the aircraft in the X-Plane world now use the
EXACT SAME FLIGHT-MODEL CODE, and your plane, and others, can have
weapons systems with proper guidance and countermeasures!
This is more amazing than you might think: It USED to be that the
OTHER craft in the X-Plane world tooled along simple, straight lines,
obviously following a very simplified model... you could tell the
other planes were really fake. When you would fly formation with
them, they always went perfectly straight, never moving with the air,
and never maneuvering realistically. This was pretty weak.
Now, all that is changed: The VERY SAME FLIGHT MODEL CODE that drives
YOUR airplane now drives ALL the planes... and you can have up to
TWENTY planes in the sky with you now. This means the other planes
fly as realistically as yours, right down to rocking and rolling in
turbulence, turning and climbing and descending realistically, and
moving with the wind. Formation flight with them is now accurate,
right down to getting in their wake turbulence. (As well, they can
get in yours, and you can watch them roll and buffet as they fly
through your turbulence). To see this in action, go to the "Other
Aircraft and Situations" windows in the "Settings" menu... crank in
maybe 10 planes, and set them all as BLUE team, and set YOUR plane
(the very top-left check boxes) as RED team. (If you want to live, do
NOT let any of the other 10 planes be FIGHTERS! You can guess why.
Select other planes with the little gray box beside the airplane
name, same as always.) Now, select each of the OTHER 10 or so planes
to be of similar performance to YOUR airplane. Are you in an
airliner? Then select airliners or other hi-subsonic planes as the
other planes. Are you flying a General Aviation plane? Then select
slower other planes. Once you have done that, close that window and
get your plane in flight at some medium speed and altitude on
autopilot. Let it fly for 15 minutes or so. Go get a drink maybe.
Come back after maybe 15 minutes and switch to the external circling
view ('|' key) and use the shift-arrows to circle around... see
anything interesting? Since you have selected a team for those planes
that is different than your team, they want to chase you down. If you
had chosen any of them as being fighters... well... try that if you
like. Now hit the '/' key to show flight model. Now turn on some
turbulence in the Set Weather window. Now you will begin to
understand the amount of math that is going on here. Now, go back to
the "Other Aircraft and Situations" window and UN-CHECK the TEAM
check boxes for all the other planes. Since they are not on a team
opposing you, they will no longer chase you down. Close the window
and try to fly behind them... can you get in their wake turbulence?
Get in the F-22 and find an airliner at 35,000 feet.. Can you
intercept him? Fly in his wake? Can you get in a helicopter and
intercept a slow-moving Cessna? Can you see how his wake interacts
with your rotor? (Not as much as with the wings on a plane, thanks to
the high blade loading and hi speed of a helo rotor, but the effect
is still there!)
OK, now that you are in a fighter, and can see how to make OTHER
planes fighters, and see how to put different planes on different
teams, you can guess where this is going, yes? Grab the "Japanese
Anime" in the "Science Fiction" folder for your plane and set about 5
or 6 other planes in the "Other Aircraft and Situations" window and
set them all to be fighters (F-4, F-22, Japanese Anime... whatever).
Set them all to be on a different team than you. (Remember, if you
have NO team selected for a plane, then it will wander aimlessly.
Select a team to make it aggressive, chasing down anyone NOT on it's
team!) Now that you have the OTHER planes on the red team, and YOU on
the blue team, close the window and go flying, and good luck. If you
are a girly-man, then set half the other planes to be on YOUR team,
so the artificially-intelligent planes will fight EACH OTHER... you
can fly around and watch them fight!
Now, to add to the fun, we have a handful of new weapons-systems
switches that you can put on the panel (all in the 'weapons' folder
as accessed by the Panel-Editor in Plane-Maker). As well, you can add
the 'console' instrument in the 'Weapons' folder to your instrument
panel... all weapons on your plane will show up there, and you can
click on weapons to select them. As well, the HUD will show a
rectangle to indicate your target when air to air guns or missiles
are armed, and a circular projected-path indicator will show up on
your HUD when bombs are armed. Arm missiles or guns and use the { }
keys to cycle through targets... selected targets will turn red on
your moving map, and guide the target rectangle on your HUD.
Ok so that is how you shoot others.. but how do you defend against
others shooting you? Chaff and flares! Grab the chaff and flare
buttons in the panel-editor from the 'weapons' folder so you can
mouse-click to deploy them, or just assign joystick buttons to deploy
them. Select the amount of chaff and flares you have to deploy in the
"Systems" window in Plane-Maker. Flares confuse heat-guided missiles,
chaff confuses radar-guided. You can open weapons up in the 'Edit
Weapons' window in Plane-Maker to see if missiles are heat or radar-
guided, and open the 'Default Weapons' window in Plane-Maker to see
what weapons various planes have. (The fighters and Japanese Anime
are the armed airplanes). Based on the type of weapon the that is
being fired at you, you should decide whether to deploy chaff or
flares. (Note: A rapid beeping indicates that someone has a radar-
lock on you: a good time to deploy chaff... though someone (either AI
plane or multiplayer opponent) could easily keep a radar lock on you
for hours at a time if they are just following you around, and seeing
as how chaff disperses and becomes useless in a few moments, being
too quick to deploy chaff could negate any advantage it may have
given you). The Japanese Anime fighter in the 'Science Fiction'
folder has all this stuff... assign a joystick button to 'Flares' and
switch to an external view while you pop them.. looks kind of cool.
Turn on other planes and set them to other teams than you to fight
against artificially-intelligent airplanes. Use multiplayer to play
against friends, using all of these systems. Design your OWN fighters
with these systems... no need to be content with what's out there now.
Another weapons type: LASER weapons.: Throw a laser on your plane and
shoot down you friends in a multiplayer game... or any other plane in
the sky! My "Japanese Anime" has a laser now... arm it by turning on
the GUN switch.. and fire with the space bar or joystick button. This
simulates mock aerial combat where you can chase each other around
with lasers to simulate guns.
NOTE: X-PLANE DOES NOT SIMULATE DEATH OR DESTRUCTION, SO X-PLANE IS
NOT REALLY A COMBAT SIMULATOR. TO AVOID THE VIOLENCE OF A COMBAT
SIMULATOR, BOMBS HAVE NO EFFECT ON ANYTHING ON THE GROUND AT ALL...
THEY DETONATE AND SMOKE SO YOU CAN SEE WHERE THEY HIT, BUT THEY DO
NOT ACTUALLY DAMAGE ANYTHING ON THE GROUND. AS WELL, AIRPLANES ARE
NOT DESTROYED BY BEING HIT. IF YOU ARE HIT WITH A MISSILE, GUN, OR
LASER OF ANOTHER PLANE, YOU WILL PUFF-SMOKE AS IF YOU WERE IN A
TRAINING EXERCISE, AND YOUR ENGINES WILL BE SHUT DOWN TO LET YOU KNOW
YOU ARE HIT. THIS OCCURS BOTH WHEN PLAYING AGAINST THE ARTIFICIALLY-
INTELLIGENT PLANES, AND YOUR FRIENDS IN MULTIPLAY MATCHES. YOU AND
YOUR FRIENDS CAN NOW ENGAGE IN MULTIPLAYER COMBAT IN X-PLANE IN ANY
AIRCRAFT YOU CAN DESIGN, WITH THE UNDERSTANDING THAT HITS AGAINST
YOUR FRIEND WILL SHUT HIS ENGINE DOWN AND CAUSE HIM TO PUFF SMOKE,
MUCH LIKE A 'RED-FLAG' STYLE TRAINING EXERCISE WHERE FRIENDS COMPETE
IN AERIAL COMBAT, BUT ACTUAL DESTRUCTION OR DEATH DOES NOT OCCUR. WE
WANT TO SIMULATE THE COMPETITIVE ASPECTS OF AERIAL COMBAT, MUCH LIKE
IN A RED-FLAG EXERCISE, WITHOUT SIMULATING THE DESTRUCTIVE ELEMENTS.
Bird Flocks!
X-Plane had helicopters, Seaplanes, and artificially-intelligent Air
Traffic Control well BEFORE Microsoft Flight Sim, and they came along
after us with their imitation every time. Now, we are beating them
AGAIN. We now have:
FLOCK OF BIRDS! Is simulating flocks of birds silly? Well, I used to
think so, until I was running my Cirrus (in reality) up to take-off
speed to go flying and a huge flock of birds suddenly shot up out of
the grass right beside the runway and dashed over the runway right in
front of me. They were in front of and above me, and I figured I just
MIGHT be able to fly through a hole in the flock and get through in
one piece, but I yanked the power and slammed on the brakes to abort
the take-off and avoid the collision. It was EXACTLY like a drag
race: FULL POWER to 100 and then yank the power and slam on the
brakes.. REALLY fun.. and, if you have seen what happens when a bird
comes at a windshield before, you realize it was a very good idea to
lay on the brakes and stop rather than have an in-flight collision
with a bird. Now, how does this correlate to X-Plane? Well, go to the
"Rendering Options" screen and turn ON the "Flocks of birds" option.
Then, go flying. You might get lucky for one take-off. Or maybe 10.
Or maybe 20. But keep flying.. soon enough, you will see a bunch of
little white dots in your path during low-altitude flight around the
airport. My advice: Fly right into that flock of little white dots.
What's the WORST that can happen? ;-)
Overhauled tire forces!
I have now improved the tire dynamics according to the theory of tire
dynamics presented in (automotive) racing literature.
You may not NEED tire dynamics good enough to handle automotive
racing physics, but X-Plane has them now anyway.
For sideforce, the model provides a sideforce that builds up to peak
as the slip angle of the tire approaches 10 degrees, as in reality.
Then, as in reality, the tire shifts from static to kinetic
coefficient of friction as the total required force exceed the
available friction and you enter a skid.
Remember, in reality, a tire can NOT put out as much SIDE force if it
is also being asked to put out a LONGITUDINAL force!
...So this math does consider the braking, driving, and side forces
on the tire, so if you are in a tight turn and hit the brakes, the
total required force
to turn and brake at the same time will exceed the total available
tire friction and you will transfer to kinetic coefficient of
friction and enter a spin.
For longitudinal force, you have rolling friction, but transfer to
static friction as the brakes engage, and kinetic coefficient of
friction if they lock.
All of this is very simple and common, but X-Plane now takes it to
the next level:
X-Plane can now handle locked brakes and spinning tires, with the
longitudinal and side force vectors able to handle any skid angle
and any tire rotation speed (in any direction), always opposing the
molecular bond between the rubber and the road, no matter what
direction the bond is dragging across... Now here is where it gets
complicated... the direction of this bond is NOT simply equal to the
sliding direction of the tire!
Why? Because the SPINNING of the tire changes the direction of this
bond as well! This is why tires lose their ability to steer
when they are locked (skidding, not turning) but why front-wheel
drive cars can still turn under full power even though the front
tires are skidding,
but DRIVING the car! (but not locked, STOPPING the car)
Now, you may have to think about that one a moment, but:
1: If a front wheel drive car has the steering wheel hard over to the
side with the front wheels SKIDDING AND LOCKED, then the wheels will
provide ZERO turning ability! You might THINK that turning the
steering wheel will make some difference if the front wheels are
locked, but you would be wrong. When the rubber is just dragging down
the road with no tire rotation, it makes absolutely no difference at
all what direction the tire is facing: it's just a dragging piece of
rubber.
2: But if those front wheels are SPINNING MADLY UNDER POWER, then
they still DO provide turning ability since they are dragging their
bond ahead and in the direction of the steering wheel input! To
imagine this, just imagine a front wheel drive car STOPPED, but with
the front wheels turned off to the side a healthy dose and the wheels
spinning madly under full power. Clearly, the car WILL accelerate OFF
TO THE SIDE, thus providing turning ability of sorts: Turn the wheel
left, and the tires drag the front of the car to the left. Turn the
wheel right, and the spinning tires will drag the front of the car
off to the right. So you have two cases of a front-wheel drive car
with skidding front wheels, but totally DIFFERENT steering dynamics!
Why? Because the friction between the rubber and the road always
opposes the direction the rubber is being dragged across the
pavement... and you need to look at the tire sideslip angle AND the
tire rotation speed and direction to resolve in which way this force
acts. The tricky part is that no matter the sideslip angle, skidding
speed, and tire spin speed, the total force the tire puts out (sum of
ALL directions!) can never exceed the available friction. This is why
cars can not ACCELERATE very strongly when in a tight turn: the tires
are already near their maximum friction pulling the car around the
turn, so very little friction is left to accelerate or brake. This is
why it is easy to spin out a Corvette... put the car in a tight turn
so the tires are near their maximum friction: then add judicious
power and the torque on the wheels requires more friction to resist
tire-spin... friction that is not available because the tires were
putting out maximum force just holding the car in a turn. Since the
friction is not available, the rear tires spin. This transitions them
from static (lots) to kinetic (little) friction, initiating the (very
violent and fun) spin.
Try this in a front-wheel drive car and it is different story: When
you add power the tires spin madly and transfer from static down to
kinetic coefficient of friction, but since the rubber on those front
tires is being dragged across the road in the desired direction of
travel, very little happens in the way of spin-entry... those tires
are just dragging you along in the direction you are pointing the wheel.
Anyway, all of this is now simulated in X-Plane, and even though you
do not have the ability to actually DRIVE the wheels with engine-
torque, the physics are there, and still apply even when the wheels
are just rolling or locked, as can happen in the sim. Turn your
airplane and hit the brakes while turning, and the braking wheels may
go over their max available friction and the spin-entry begins... it
can happen in an airplane just like it does in a car. (The difference
is that the airplane has the big vertical stabilizer which provides a
huge aerodynamic stability, making spins much less likely, especially
at high speeds, where aero forces dominate. Of course, the vertical
stab does not help you out so much at low speed, where the gear
forces dominate).
OK, while I was at it with the tire-modelling, I decided: "Why stop
there?" and made a REALLY nice new anti-lock-braking-system model.
This model actually applies and releases the brakes to keep you right
on the ragged edge of your available friction, and you can really
feel the brakes clamping and unclamping right at their limit,
complete with the resulting steering instability and little skid near
the end as the wheels lock for the last little bit of the stop... the
whole 9 yards!
Now, to give the best surface for exercising this model, if airport
the flattening is turned off then the airports follow the terrain
contours perfectly... unlike previous versions where the pavement
might not quite follow the terrain. Now, the "pavement" is now
perfectly "draped onto" the ground, just paving a real runway.
Visual Improvements:
New better-looking lights for the airplanes, objects, airport
runways, EVERYTHING. These new lites are better looking and are
FASTER as well for improved frame-rates.
New sky-colors to give better sunsets and day and evening lighting,
as well as refined lighting from the sun. The water also reflects the
sun colors, to give really realistic water appearance, especially
around sunset. Place aircraft by airport to KAVX. Switch to '|' view.
Zoom out with shift-minus key and shift arrows to move around. Set
the time of day to around sunset and circle around to see the cool
water effects.
As well, the moon is now actually 3-D as well. This moon should
always have lighting acting on it that is perfect for the current sun
and moon locations. And we have new refinements in our orbital
rendering... stars, clouds, and planet visibility are all more accurate.
We also have up to 3 cloud layers now. This applies to manual
selection, rendering, real-weather... everything!
Try setting 3 different broken layers and flying around between
them... pretty fun. While working cloud-like stuff, we improved smoke
and contrails from the aircraft as well.
Now we have moving cars on the roads.
YOU CAN NOW MOVE AROUND INSIDE THE AIRPLANE! It's the coolest
thing... open the Bombardier in the Seaplanes folder and hit control-
o. Now look around the cockpit with the mouse. Got it? Ok, look
straight ahead with the mouse now and then hit the a/s/d/w/r/f
keys... COOL!
Hit control-o again to get out of that mode.
Speed Improvements:
More frame-rate optimizations! You should see good frame-rate
improvement with only ONE plane selected (no other aircraft in the
sky other than you) compared to X-Plane 8.40, even though this
version does MUCH MORE. Frame-rates will of course go down as you
load up the sky with other airplanes, since the other planes are
running full flight models. As well, lights at night are now MUCH
faster... flying in city areas at night is now a good bit faster.
Airports draw faster as well... you will see significant frame-rate
gain around large airports.
Scenery-shift speed-up... transitioning to new scenery areas now has
less of a load-time delay. Getting a multi-processor or dual-core
(NOT HYPER-THREADED!) machine is KEY in getting this load time down
even lower for you.
General New Features:
Multi-windows handled lots better... on a Mac with a huge monitor,
just check the "draw cockpit on second monitor" option
to get a second window that you can drag around with the cockpit on
it. (Note: You may have to drag the cockpit window aside right away
to see the window underneath!)
Checkbox in rendering options screen to load scenery (nor not) is
back, so you can establish a general flying area with the aircraft
placement, and then never pause to load scenery... though you will
need to stay in your 120x120 mile flying area of course!
You can't SEE this one, but the code has been made much more object-
oriented and compartmentalized to minimize any accidental
interactions between various different parts of the program. This
makes bugs and crashes much less likely, and has a speed advantage as
well since memory is accessed in tight, small, pre-defined regions
rather than spread out across huge arrays.
You can't SEE this one, but joystick, internet, file i/o, threading,
and countless other things have been streamlined by finally dropping
support of old Mac O-S 9... the code is now shorter, tighter, and
more consistent. (the only code than can never cause a problem is
code that does not exist)
As well, X-Plane now uses the same (proprietary) networking code
interface for Mac,Windows, and Linux!
(...less chance of bugs in those things now. This really tightens
things up.)
You can't SEE this one, but countless arrays of data are now moved
into vectors, which allows them to be bounds-checked (when in
development) to be sure that we never access a single bit or memory
that is out of range (a common cause of bugs and crashes). This
bounds-checking is turned on during development, but turned off for
release so there is no reduction in speed in the released version of
X-Plane.
You can't SEE this one, but the airports are now generated and
displayed using the same code that has historically been used for the
REST of the terrain, reducing the amount of code and also increasing
the speed.
Refinements:
The NAVAID editor option in the map screen lets you edit FIXES now as
well, and, um, works right.
Entering a wind SHEAR speed greater than the wing TOTAL speed will
not cause the wind direction to flip 180 degrees as the wind shears
to the other direction... enter a shear direction of 180 degrees if
you want that to happen.
Manifold pressure modelling and various other engine parameters are
tweaked out a hair based on SR-22 flight-test.
COMPLETE failure state saved for EVERY frame in the replay and
movies... so every replay and movie will show EVERY failure on the
plane.
(Currently, X-Plane allows up to 655 different equipment failures. I
think that is enough for now.)
Better TCAS system on the EFIS map.. the arrows by the traffic
indicate climb or descent rate, and color-coding is better
we have white, orange for danger, and red for HIGH-danger of collision!
Pressurization system is a hair more accurate... the system will not
dump excessive pressure if you command too low a pressure altitude
for the cabin... instead, it will dump JUST ENOUGH to keep you in
limits.
Separate supersonic DOWNWASH model from the wings to the
stabilizers... should be a hair more accurate.
Refinements in the flight model to improve induced drag and tip-loss
accuracy...
this will improve the accuracy of the lift and drag from flap
deployments a bit.
Autobrake logic is more thorough... the system engages when armed (to
the left of the EFIS on the 777),
but if you hit the brakes manually (b or v key, or joystick button,
or better-yet ch pro pedals), then that DIS-engages the autobrakes
and you are then braking manually. Advancing power (in landing, but
not RTO mode) or turning off the autobrakes will also disengage them,
as in reality.
The radio volume in the sound window now controls the volume of the
artificially intelligent ATC as well.
3 digits for wind speed on the various HUD and EFIS displays, as
often needed in the flight levels.
Joystick screen now automatically keeps you from entering conflicting
axis assignments.
Highways are "hard"... you can land on them like you used to be able to.
If you send in ITT or EGT by UDP then the X-Plane model for those
variables is over-ridden.
Custom angular limits for the APU N1. Well, jason wanted it.
Joystick button option to switch fuel tanks.
This mouse wheel will control the throttles. Because... umm... you
might want to control the throttles with the mouse wheel.
Dozens of other little refinements here and there.. far too numerous
to mention.
Bug Fixes:
Aircraft object as created in Plane-Maker using the "aircraft to
object" function should go to the same
folder as your copy of Plane-Maker, not to the outer level of your
hard drive.
Joystick prop fine and coarse buttons work with both constant speed
and variable-pitch props.
ATC no longer confused about what airport to vector you to when you
need vectors to an airport with a common name.
You can change language and have all the menus all remain intact.
Dozens of other little tweaks and fixes here and there.. far too
numerous to mention.
Oddity-Of-Austin: (cool new feature I wrote mostly for myself cause I
might be the only person to use it)
New autopilot mode selector: RE-ENTRY!
Do this:
Get in my MegaHyperSonic ("Austin's Designs" folder).
Use the planet map place it over Australia.
Use the "Low Enroute" map to place at 400,000 ft, 14,000 knots,
heading 45 degrees.
Dial KEDW into the FMS.
Turn OFF all the engines.
Hit the ENT (re-entry) autopilot button on the autopilot.
Dial in 450 knots into the autopilot speed selection window.
Sit back while the plane flies a re-entry and takes you to edwards.
How does this work?
It is a lot more complicated than you think... you can NOT just
"glide home"... here is why:
When you are high up in space, you are going 17,000 mph with nothing
at all to slow you down... there is no air so slow you.
When you are down low in the atmosphere you are going maybe 1,000 mph
and decelerating hard... the air is thick down there.
When you are up high in space, you MUST go fast, because if you were
slow, you would simply plummet (no air to lift with) and not be able
to pull up in time once you finally got into the atmosphere
When you are down low, you MUST go slow, because hi speed (anything
like orbital speed) would rip the plane apart.
So you have to gradually slow down as you go down, going fast up
high, and slow down low.
Here is why this is hard, though: When you are in the first 85% of
the re-entry, you are way up in space covering maybe 250 miles per
minute...
An error in descent of even ONE MINUTE will put you 250 miles off
course... which will take maybe half an hour to correct when flying
down low.
Since even the tiniest slip-up in your navigation when moving FAST
will take a long time to correct later on when moving SLOW,
you need to avoid any error at all in the early part of your
approach, where you are covering ground really fast. (tiny mistake
now = huge correction later)
The problem is, in space, with the engine shut down, you have almost
no ability to maneuver, so it is very difficult to nail the re-entry
corridor!
Now, in theory, you can say "all right, I will just ease it down slow
into the atmosphere, slowing down as I descend, so I never overspeed
the plane"
But in the early part of the re-entry, even the TINIEST amount of
lift WILL push you back into space, because thanks to the centrifugal
force of orbit,
the plane will stay in the air with ZERO lift (centrifugal force is
holding you up at that point, no lift is needed!)
Because orbital centrifugal force will hold you UP, so even the
tiniest amount of lift will fling you right back into space, you need
to find a way to add
DRAG (to slow the plane) WITHOUT adding any LIFT at all (which would
pop you right back into space).. how do you do this? By BANKING.
Put the plane in a 90-degree bank and pull on the stick and you can
get plenty of drag to slow the plane, but the lift of the wings is
NOT pulling
you up into space because the lift is only pulling you sideways,
thanks to the fact that you are in a 90-degree bank.
Remember, though, that any navigation error you make here by going
off-course will be 50 times harder to correct later on when you are
down in thick air, hardly moving.
Basically, the way the atmosphere is laid out, almost ALL of it is
below about 50,000 feet, even though SOME of it goes up to 500,000
feet. This means that almost all of the air will be encountered in
the last 10% of the descent. This means that almost all of your
deceleration will occur in the last 10% of the descent. This means
you will come screaming in and in and in and in and the suddenly
STOP right at the end.
The problem with this is that since you are stopped at the end (very
low speed below 50,000 feet), any error you made getting to that last
50,000 feet of atmosphere cannot be easily corrected... the tiniest
error at the beginning of the approach will have you come down in
Cleveland rather than Edwards, and that will take forever to make up
by flying down low, and is of course impossible to make up without
starting up the engines, which may not have any fuel.
So, how do you fly the approach? By easing down into thicker air
little by little as you slow down,
banking to bleed off energy without climbing,
switching your bank angle from left to right a lot to keep from
getting off course,
and choosing an altitude to give you a deceleration that will bring
you to a stop just as you reach Edwards.
The HIGHER an altitude you choose, the LESS air drag there is, and
the less deceleration you will have, and the more likely you are to
overshoot.
The LOWER an altitude you choose, the MORE air drag there is, the
more likely you are to come up SHORT of your target!
So how do you choose your altitude?
Well, look at the re-entry instrument I have thoughtfully added to my
MegaHyperSonic EFIS right under the artificial horizon:
It gives the deceleration (in G) needed to come to a stop just as you
hit whatever destination is dialed into your GPS!
Is the DESIRED deceleration at 0.5 G, and your CURRENT deceleration
at 0.2 G? OOPS! You are not slowing down enough! You will overshoot
Edwards and wind up in the Atlantic (not Pacific) Ocean! You need to
descend into thicker air to slow down more! How do you do that?
Well, enter a HIGHER number into your autopilot airspeed entry when
in RE-ENTRY autopilot mode and watch the plane descend to try to get
a higher airspeed.
It does NOT descend because it thinks it will speed up by
descending... nothing could be further form the truth! You are
already going so fast
that you will not gain any noticeable speed at all by descending a
mere 200,000 feet... the reason that descending will give you a
higher INDICATED airspeed as that you will have exactly the same REAL
speed, but it will be in thicker air, so it will INDICATE a higher speed
on the airspeed indicator (remember, the airspeed indicator measures
pressure on the airplane.. it is basically an indicator of the square
root of dynamic pressure, or pressure of wind blowing against the
airplane). This, of course, will result in more aerodynamic drag,
which will slow you down faster, which will cause you to come down
somewhere in the USA rather than overshooting to the Atlantic ocean.
So you have to remember it like this: your REAL speed does NOT change
except over the course of maybe 30 minutes or an hour.
You cannot change your real speed. You have to accept that. The
inertia is just too great.
Your only hope at managing the flight is to control the drag on the
plane by controlling your INDICATED airspeed.
And you control the INDICATED airspeed NOT by speeding up or slowing
down (you can't) but by going higher or lower, into thinner or
thicker air.
The more you want to slow down, the more you push the nose down.
That bears repeating: IF YOU WANT TO SLOW DOWN, THE LOWER THE NOSE
AND DESCEND, TO GET A HIGHER INDICATED SPEED.
This is opposite from everything you have learned, but you must
understand it to say "Gee, I am too fast, and I will overshoot the
entire
North American Continent. I must slow down. So I must lower the nose
into thicker air which will slow the plane. So I must a higher number
into the re-entry autopilot speed, so the autopilot will dive me down
into thicker air to get a higher indicated speed, to give me more drag,
to slow me down."
Everything is backwards, but if you understand it, you will be able
to do a re-entry every time, and bring it from Australia to Edwards
Air force base, right down to the runway, without ever starting the
engines.
I can do it. Can you?
austin
|
c'est tout moi 
) corrigé (il date quand même de la version 6 ou pas loin 
.
c'est vieux comme news hein... 
