OK so a few months ago, 844X had flown in primer and no interior with the standard Lancair avionics package. This package consists of:
Two Garmin G-900’s for primary display and map.
A Moritz display for control of pressurization, air conditioning, some power switches, and the like.
An L-3 Trilogy backup attitude indicator, to show the pitch, roll, altitude, and airspeed of the aircraft in the (almost unheard-of) event that the (really quite good) Garmins stop working.
A bunch of mechanical circuit breakers that customers mount in various locations that pop out if current ever goes over-limit.
One of the purposes of 844X, however, is to be a test platform for the Vertical Power VP-400, which is the artificially-intelligent Runway-Seeker that is designed to choose the best landing site for you in the event of engine failure or pilot incapacitation, and even take you down to that runway on autopilot at the push of a single red button. (I wrote the software for the VP-400, with the exception of the inter-aircraft communication and control, which is by Vertical Power). The Vertical Power VP-400, as part of this power, gives a full synthetic vision display in the upper half of the touch-screen interface, completely obviating the need for the L-3 Trilogy. As well, the VP-400, in the bottom half of the touch-screen, lets you control air conditioning, pressurization, and the like, obviating the need for the Moritz display. As well, the VP-400 has an electronic circuit breaker panel that can be invoked in the bottom half of the touch screen, thus obviating the need for mechanical circuit breakers.
Replacing the Mortiz, Trilogy, circuit breakers, and associated wiring with a single VP-400 unit will result in a huge decrease in panel-clutter, wiring, and weight, as you will see as you read on. The primary purpose of the construction of 844X is to be a development testbed for this new VP-400 technology, and we have to have it ready for Oshkosh if it is to be shown to all… so we sort of have a “Monster Garage” situation here, where we have a fascinating mission to accomplish, and a very tight time-table in which to do it.
So, with the airplane JUST out of the paint shop (in pieces: the fuselage, each wing, each control surface, and upper and lower cowling delivered separately!), the time had arrived to:
1: re-assemble the now-painted pieces of the airplane
2: remove the stock panel with the Moritz and L-3 and circuit breakers and install an entirely new instrument panel with a Vertical-Power VP-400 in it.
3: fly the remaining 20 hours that needed to be put on the airplane to achieve the 40-hour test-flight period… much of this would be done by me. (gulp)
4: fly this thing to Oshkosh!
We had a pretty tight schedule to do this… 10 days, in fact, since that is when Oshkosh starts (!)
All of this work had to be done with the following parties:
1: RDD of Redmond, OR (build-shop that oversaw construction of the airplane)
2: Vertical Power of Albequerque, NM (company that developed the VP-400 A-I Runway Seeker)
3: Laminar Research (well… ME, anyway)
All assembly and test-flying would be done in Redmond, OR, at RDD’s facility, before the cross-country to Oshkosh.
My plan was to show up at RDD at T minus 10 days to help with final assembly and VP-400 installation and programming, and general oversight of the airplane to be sure that it went together in a way that I liked.
Play-by-Play to follow:
T minus 10 days:
So, I arrived by airliner (sigh) in Redmond at midnight, and grabbed the rental car (a light and springy little Ford Focus… very nice handling) and went racing up the mountain to the rental house in Eagle Crest, 10 minutes outside of town. The rental house was in a gated community (I HATE gated communities!) and of course nobody had ever given me the gate code, so I was up until 1 am making phone calls to get that sorted out. Trust me: I was VERY tempted to go off-road and drive right AROUND the gate and into someone’s back yard and then into the gated community in the little Ford focus, but there would have been uncomfortable questions to answer when I returned the car in 10 days with the paint all scratched from driving through the shrubbery. Finally arriving at the rental house at 1 am with nothing but airline food in the 12 hour trip from South Carolina, I discovered that the refrigerator in the rental house was stocked with the following food: Butter.
T minus 9 days: (switching top present-tense since I am updating daily)
Bright and early to RDD, N844x was sitting in the hangar in, if I may say so, a rather confused and chaotic state of glory.
To the UNTRAINED eye, one would see a stunning, sleek, swoopy carbon-fiber body elevated high above the ground, with a complex set of piping around the long aluminum cylinder that makes up the engine sticking out the front, and a variety of wires and cabling going into it’s various doors from various tools and plugs in the hangar, and people scrambling all about it, readying it for flight.
To the TRAINED eye, quite a few other oddities stick out.
=>The plane is sitting on jacks so the landing gear cycling can be tested, and ladders are needed to access any door into the airplane.
=>The tail is NOT quite normal. Unlike a stock Evolution, which has a nearly straight-up vertical stabilizer jutting abruptly out of the body (much like a P-51 Mustang), the tail on this plane is much more SWOOPY, following a long, smooth curve from the fuselage up to the vertical stab. This is much more like a classic Lancair in appearance.
=>The nose is not quite normal. UNlike a stock Evolution, which has a fairly flat nose and windshield suddenly jutting up (again, much like a P-51 Mustang), the nose sort of blends up into the windshield for a more classic Lancair look.
=>As well, the prop is not the heavy aluminum Hamilton propeller, but is instead a lightweight composite German MT prop (4-blade, light grey, with metal leading edges) that shits down the FEATHERED position, leaving the blades completely streamlined (turned perfectly into the wind) as the craft sits on the ramp, giving a very distinctive look on the ground. As well, this prop sits a few inches farther forward than on a stock Evo, since it is riding on the front of a longer engine… a Pratt and Whitney PT6-A-42, which packs 850 hp, as opposed to the stock 750.
>As well, if the cowl were installed (right now, it isn’t) one would note that the air intake is non-standard, but is instead a little more curvy, perhaps following local streamlines more closely.
=>The careful observer, if he looks inside, would also notice that the panel is completely different.. not even one bit of it is from a standard Evolution (!) A normal Evo panel has the Garmin G-900 primary and secondary displays sitting LOW on the panel, RECESSED BACK a bit, with the various switches for electrical systems sitting ABOVE them, and slightly CLOSER to the pilot. This arrangement is great at keeping the Garmins in the shade so you can always see them, but rides those displays sort of low… sort of lower than I might find optimal, since I glance down from the windshield to see generator and battery switches in my immediate line of vision. In THIS Evolution, though, the panel is totally FLAT.. nothing is recessed or advanced, and the switches re BELOW the Garmins. This puts the Garmin PFD FRONT AND CENTER, very closely aligned with your vision, as high as it can be in the panel. The MFD sits at an equal distance to the right, and the VP-400 sits between them. The switches are lined up in a row underneath them, flowing fro left to right across the panel in the order they are access in flight. This panel is the result of about 3 days of discussion between myself and RDD, and about 3 revisions on paper. WIthout a SINGLE gauge on the airplane (the VP-400 is the backup.. FAR more reliable than the typical mechanical backups) you see only 3 computer screens on a flat grey panel, with a row of switches beneath them. It is actually sort of hard to believe that such a simple setup could do so much! This is an airplane that literally has no gauges… only 3 computer screens! WIth only a few computer screens on flat black metal, the panel looks TOTALLY military. Really, not civilian at all.
=>An especially trained eye would note that the airplane has a paint scheme that has very little overlapping stripes, resulting in less weight in paint. As well, one might notice that the airplane is NOT ACTUALLY WHITE, but is instead a creamy off-white that WEIGHS LESS THAN WHITE because it can go on in a thinner layer of paint and still give total coverage, because it has a light-absorbing color.. perfect light reflection is not needed with any color other than white, so the layer of paint can be (and is) thinner. In fact, the flight controls were built with lead in them ahead of the hinge-line to balance the weight of the control surface that sat behind the hinge-line… and that lead was measured during the construction of the flight controls to offset the weight of standard bodywork and paint. Since I sanded off all the bodywork, and Tom Connors (paint guy) designed such a thin layer, the lead allocation turned out to be all wrong and workers had to drill into the flight controls after the paint was done to REMOVE half the lead from the controls! We actually did a careful enough job with body and paint to “break” the design of the airplane.
At first, all I could do was sit there, mouth sort of agape in a silly grin, and stare at it as RDD workers scrambled about it, rushing to hook up the myriad of electrical systems needed to make ready the entire new panel. But, of course, you don’t sit there staring forever, so soon I was asking what I could to help. During the construction of the airplane, I played a pretty significant part, because they could give me resin, carbon fiber, and some plans, and then leave me alone for a while to slave away. The work was easy to learn, and if I messed up the occasional part, well, as Jay Leno says about Doritos: “Crunch all you want… they’ll make more”. Final assembly is NOT quite like that, though. EACH BIT of the final assembly is different, and EACH BIT should be performed by an expert in that area. A guy with FLIGHT CONTROLS EXPERIENCE should hook up the rudder, elevator, and ailerons to the wings and control-arms. A guy with DOOR experience should hook the doors back up. A guy with good ELECTRICAL and PANEL experience should be the one wiring the panel. My best skill, really, is providing them with coffee and the occasional fan to blow air through the airplane, or tool or part, and to answer questions from them about what system I wanted set up what way. Near the end of the day, it was clear that my best time-use was to work on software updates to the VP-400, and updates to X-Plane 10.10 beta, which is going on at the same time. (yah. busy.)
T minus 8 days:
The new instrument panel is now running, and looks BEYOND stunning. Seeing that dull matte black panel with the dull matte-black computer displays suddenly light up as the computer screens and internally-lit switches come to life is stunning. The layout looks to be perfection, with 3 red buttons on the panel.
Red-button number 1: The Garmin reversionary button. Hit that and BOTH Garmins go to PFD mode, sacrificing the MAP to have you attitude information if the PFD fails.
Red-button number 2: The VP-400 “red button”. Hit this, and the autopilot will engage, the aircraft heading down to the runway that it deems most likely to result in a successful power-off landing.
Red-button number 3: The starter! While most turbines have a boring light-switch type starter that looks EXACTLY like the nav-light switch (BORING!!! BORING!!!) I decided that an 850-horsepower jet-prop needed something special. While the push-button starter from a Ferrari 430 proved problematic (Ferrari won’t sell you the STARTER BUTTON without the STEERING WHEEL!) the push-button starter from a Honda S-2000 looked JUST the same, and cost about $29. Internally-lit to glow red like a hot coal, it is clear to anyone that pushing this button will invoke FIRE!
It was then time to configure the flaps and trims on the airplane, and this will involve getting into the nitty-gritty of the avionics design and layout. I hope I do not bore you going into too much detail here, but you can skim this part if you are not interested in the fine details of the way the VP-400 works.
Vertical Power designed its VP-xxx line of products to control all of the various electrical systems in the airplane (flaps, trim motors, lights, etc). They designed these systems to always be as fail-safe as possible, and to allow any critical function to be over-rided if needed. For example, to run a critical system like elevator trim, a constant series of messages needs to be generated and sent by the internal workings of the Vertical Power control unit. If the messages ever stop due to some sort of breakage in the system, the trim stops as well. This is fail-SAFE (not fail-dangerous) because if the system breaks, the airplane simply refuses to do anything exciting. Instead, it just leaves things as they are now. (In this example, it simply leaves the trim still, which is a safe occurrence, instead of letting it run without command, which is a dangerous occurrence).
Brand new for the VP-400, though, is an all-new touch-screen interface with new software written by me. This software, as initially written by me, was written in the way that all other touch-screen interfaces are written: The computer waits for a message that the user has touched the screen. When the computer gets that message, it figures that the screen is being touched until it gets a SECOND message… this message being that the user has lifted his finger OFF the screen! It seems simple and common-sense, right? The computer gets a message from the touch-screen that the pilot has touched the screen, and then a little bit later a message that the pilot has STOPPED touching the screen.
But, what if the message that the pilot has stopped touching the screen is somehow lost due to some sort of error in the computer or touch-screen?
Think about it: In that event, the computer will THINK that the pilot is HOLDING A BUTTON DOWN on the touch-screen down… even though he is not!
And, what if that button is, for example, an elevator trim button?
In that case, my computer program would be fooled into thinking that the pilot is holding down the trim button, and would inform the Vertical Power system accordingly, and the trim would continue to run… all because a single message from the touch-screen that the pilot had lifted his finger off the trim button was lost. (And, to non-pilots: A trim that motors along without command is among the most dangerous things that can happen in an airplane, because the airplane could diverge from pilot control, slowly but surely).
Accident reports throughout aviation history are littered with these odd little cases that only become apparent in retrospect.
So, after actually seeing this happen in our systems-testing on the ground (!), we decided to build the VP-400 in such a way that it would be totally immune to this type of failure in flight. But how? The internal workings of the VP-400 were already fail-safe… now we just needed to make sure that the touch-screen interface was equally robust. The answer came to me rapidly: SWIPING. You know how when your iPhone rings, you have to SWIPE the little button across the screen to answer the call? This is slow and annoying, but it makes pretty darn sure that your phone is not answered by mistake as it moves around in your pocket, right? A very specific action needs to be taken that only a human would take, and while it may be slow and annoying to take, it sure does stop your phone call from being answered by mistake. This is exactly the key to a fail-safe touch-screen interface, and exactly what we designed into the VP-400. Here is how it works:
1: The trims (elevator, aileron, and rudder) are normally controlled by a hat-switch and another switch on the yoke or control stick. These trims must be held down to close a circuit that runs the trim.
2: If that circuit breaks, then the user may go to the backup trim control panel in the VP-400. There, the user SWIPES across the screen for each LITTLE BIT of trim that he wants! So, if he wants a LOT of trim, he will need to sit there swiping over and over to drive the trim, much like a cat scratching a scratching post. Each bit of swiping that he does allows a few more trim message to be sent from the touch-screen to the Vertical Power hardware. In a nutshell: The pilot has to perform a specific action to send in each little bit of trim. If messages are corrupted or lost, then the following happens: Nothing. If messages from the touch-screen are lost due to some unforeseen errors, then some swipe actions will not register as complete, and in that case the trim simply will not move … fail-SAFE. This makes a trim runaway as close as I can imagine to impossible. This is a philosophy I am rapidly learning to code into ALL elements of the VP-400 interface.
Despite system described above that seems to me to be very well designed, I am still edgily thinking about the somewhat-scary fact we are running an experimental aircraft on a very tight schedule, and sometimes the only way to find errors is to experience them, and that I am supposed to really FLY this thing…
T minus 7 days:
SO today the app seemed to HANG.
But maybe it didn’t.
I don’t know.
The VP-400 was installed in the airplane, but the various sensors and antennae that DRIVE the VP-400 were not yet hooked up. As a result, the unit (correctly) displayed big red X’s for each function on the screen. But as we hooked up the GPS antenna, the big red X’s remained. Why? Was the GPS not really properly hooked up yet? Or were we just not getting a signal in the hangar? Or had the program crashed? Looking only a red-X’s, I had no way of knowing. I CANNOT STAND un-answered questions like that, and this would be especially frustrating in flight, so the question had to be answered.
So, a few solutions were called for.
First of all, you remember Knight Rider? The black Trans-Am with the red light cycling back and forth on the nose? That red light always cycling was how you knew that the car as thinking… so why not put it on the VP-400 so you would know that it was thinking, even if there was nothing on the screen that really needed to CHANGE? It only took a few minutes to code, and now, whenever there are red X’s on the screen because of missing data, there is at least a red light pulsing left and right (just exactly like on Knight Rider) so you know that the computer is not crashed, but is instead running, and simply waiting for valid information to come in the from the GPS and gyros and other systems to display.
Next was being sure that we never accepted bad data from any sensor. The VP-400 is designed to go through the following steps, constantly:
1: listen for data from the GPS, solid-state gyros, and pitot-static system.
2: flag that data as “received” once it GETS that data.
3: for each bit of info it shows you, make sure that is is only showing you data that it has “received” within the last one second… otherwise show a red-X for that display.
1: get a message about airspeed from the pitot-static pressure sensor.
2: display airspeed on the display, since it has received that sensor data.
3: do NOT show a red-X, since step 1 happened just fine.
Now, what if the pressure sensor was broken, and the speed that came in was 89456379864 knots?
This would be awfully confusing to the VP-400. So, in addition to seeing if the various packets of data (such as airspeed, for example) ARRIVE from the sensor, we now ALSO check to see if those packets are REASONABLE. If a packet for, say, airspeed came in, and it was over 500 knots indicated, then we now consider it to be invalid, and discard that incoming data. This packet fails the ‘common sense’ test and is ignored. If this happens for more than one second, then a red-X will go up over the airspeed display, and the system will understand that it does not have airspeed data, and will act accordingly. (In this case, by not showing airspeed or planning an emergency descent to the ground, since both of those things require airspeed).
“Common-sense” tests like this are now put on all of the attitude and navigation data coming into the VP-400, so hugely erroneous data should not be able to leak into the system. Red-X’s will result if that happens. Of course, the system is still listening for new data all the time, so if the data ever gets back into a reasonable range, the red-X’s will disappear and be replaced by appropriate displays. This will give me a nice warm fuzzy feeling when flying, since I will know that the VP-400 is constantly listening for all the data it can, showing me the latest reasonable data it has if some packets are lost or corrupted, will show a red-X if a sensor fails, and will resume normal display again if a sensor comes back on line after a temporary hiccup. As well, the VP-400 will constantly be evaluating what it needs to draw displays, plan emergency descents, etc, and doing everything that it can with whatever data it’s got.
What I am really describing here is called “degraded mode”, or “unreliable data protocol”… designs that let the system continue to function (even if in a less-capable state) as other systems in the airplane fail. It should be very, very, very hard to EVER get the VP-400 to say “I got nothing”.
Another thing we did today is test all the electronic circuit breakers. (from here on out: “ECBs”)
When I first learned that the VP-400 would have ECBs, I was not really impressed, since I only was excited about seeing the A-I runway seeker I am developing going into a real airplane. But now, having designed the nicest ECB interface I can think of, and using it in the airplane, I see that there is simply no better way to go. The ECB system is awesome, and the only right way to build a modern airplane. Here is why:
Imagine you are in a real airplane. Make it at night. Maybe IFR. Maybe some rain and turbulence going on.
A circuit breaker in the airplane pops.
This is a circuit breaker that is on a small panel underneath the instrument panel.
By your left ankle.
In the dark.
You have no way of KNOWING that it popped, unless something obvious on the airplane just stops working.
You cannot FIND it even if you know it popped.
You cannot GET TO IT without likely losing control of the airplane, since you would be fumbling around under the panel trying to find it.
You cannot tell WHICH breaker popped, since no human on or off the Earth could ever read the TEENY TEENY TINY LITTLE circuit breaker label in the dark under the instrument panel.
You would not know WHY the thing popped, so you would not know if you should reset it.
When you have to fumble around in the dark for a breaker you cannot see, with a abel you cannot read, in a place you cannot reach, popped for a reason you cannot guess, located in a place you have to reach down to get so you cannot fly, I am simply going to say: That interface is TERRIBLE.
Now let’t talk about ECBs, as we have here.
On the vertical power display, there is simply a scrolling list of electrical stuff in the airplane. Flaps. Landing lights. Fuel pumps. Things like that. This is simply a list of electrical stuff in your airplane, and you scroll though it by rotating the (single) little knob on the bottom of the VP-400. Each device lists it’s name, and shows you it’s amperage right beside it. You can read it as easy as you can read the computer you are looking at right now. (easier, actually, since the fonts are big and more brightly-colored). Systems running normally are white, and broken ones are in red with the reason they are red shown. They are on a touch screen, so simply touch any device on the little scrolling list to play around with it. (turn it on, off, or reset it if the breaker popped).
You can easily see everything going on with the entire airplane, right down to the amp drawn by every system, in a format that is so easy to access that it is ridiculous.
As well, if ANY breaker pops, the a little red-alert icon pops up on the VP-400 ECB screen selector, so you know that there is something in that screen that needs attention! This way, if a breaker ever pops, you instantly know it, because the little red-alert icon pops up to tell you! The, you just go to the ECB screen on the VP-400 (as easy as launching an app on an iPhone) and scroll through to find the breaker that is popped or otherwise alerting. It is as easy as can be, and the only way that makes any sense at all to actually use in an airplane. You could easily be flying at night, IFR, in the rain and turbulence, picking up ice, and if the red-alert icon comes up for a popped breaker, you could easily scroll to it, right on the front-and-center display, seeing in bright red text exactly what is going on, without ever getting confused or behind the airplane, or even taking your focus away from the main instruments on the instrument panel! Cool!
As well, if a system is NOT HOOKED UP, or simply unplugged or broken, with a regular circuit breaker, you would NOT have any way of knowing it! But with this ECB system, where you can see the amperage going to each system, you can easily see if ZERO amps are going to any given system. That lets you know that that system is not working… something that is not possible with mechanical circuit breakers. A number of people have crashed airplanes with PT-6 engines because the engine quit. The engine quit because a pneumatic line froze shut with moisture turning to ice. These engine had heaters on the lie, but those heaters had broken hours, days, months, or years before the accidents. The pilots never KNEW that, though, so they flew happily along with their heaters turned ON (and UNplugged!) until the lines froze over and the engines quit. With an ECB, we SEE the amperage going to the heater at every moment we feel like scrolling to the heater item in the ECB list! If we see that the amperage is zero, we will KNOW we have a problem and fix it when convenient! Compare this to the alternative if simply never knowing the thing was unplugged, and thinking everything was fie since the breaker never popped.
Also ECBs weigh less, and have less wiring. Since wiring tends to chaff and start fires over the years, this is a good thing.
So, the day was spent inside the hot cockpit on the ground in a hot hangar, going though every item in the ECB list (every electrical thingy in the airplane), making sure that I could turn it on or off (like pushing or pulling the breaker) and that, when turned on, the system worked and drew amperage.
It would basically go like this with me in the cockpit and someone else scurrying around outside the airplane:
“Turn ’em on”
“I don’t see them!”
“OK they are broken!”
“Put it on the list!”
“OK how about the fuel pump?”
“OK I turned it on!”
“All right I hear it! How many amps?”
“Ok turn it off!”
..and so on and so forth, for every system in the airplane. Sitting in a cockpit that is running about 90 degrees, and has no interior (not even a pilot’s seat yet!!!) this is really not as fun as it may sound.
Back at the house, I connect a (real) VP-400 to a copy of X-Plane in a little network that we set up on the dining-room table. X-Plane is actually spoofing the messages that come in from the REAL sensors in the real airplane, sending those messages to the VP-400 sitting on the dining room table. Now here is where it gets funny: The VP-400 does NOT know that it is sitting on a dining room table. The VP-400, since it is getting flight messages from X-Plane, BELIEVES THAT IT IS IN FLIGHT! HAR! SO here is what happens: X-Plane flies along for a few moments like a regular pilot would, and then fails the engine. X-Plane commands that the VP-400 hit the red button, which the VP-400 effectively does, and the VP-400 then glides X-PLANE BACK DOWN TO THE BEST RUNWAY TO LAND ON! Once this imaginary emergency is over, X-Plane resets to some RANDOM location, heading, speed, and altitude, and does it all over again. And so it goes throughout the night, with X-Plane imagining engine failure after engine failure, each failure at a different location and altitude, each time telling the VP-400 to bring the plane safely down to earth. For each of these emergencies simulated on the dining room table, a result is memorized, and the next morning, by me, analyzed. We start the night of imagined horrors and go to bed, always with the uneasy feeling that the VP-400 just might show a bad track record when checked the morning…
T minus 6 days:
Well, after 8 hours of simulated nightmares throughout the night, the VP-400 has scored the following:
IF the plane is high enough to glide to ANY airport at the moment the engine fails, then:
The VP-400 guided the simulated airplane down to a point just short of the runway, pointed along the runway heading and at a comfortable glide-slope, at a comfortable approach speed, so the pilot was perfectly positioned for a power-off flare and touchdown, 100% of the time.
The VP-400 then proceeded to attempt to LAND the imaginary airplane, and intersected the ground within the runway perimeters at a moderate descent rate, 92% of the time.
The VP-400 then managed to get the airplane stopped on the runway, simulating a human standing on the brakes, 98% of the time.
As overnight runs go, this is pretty typical. The VP-400 has been tested through THOUSANDS of emergencies in the simulator like this, and the scores above are now becoming pretty common: At least in the simulator, if you have enough altitude to MAKE it to an airport, the VP-400 can always set up an energy-management path that will put you looking right at the runway threshold every time, get you bumpily but without injury on the ground about 90% of the time, and even if the landing is hard, still get you o the runway in such a location that if you hit the brakes, you can get stopped on the runway almost 100% of the time (some runways are just too short for an Evolution, though, so run-offs do sometimes happen).
Now, if the schedule holds, we will fly tomorrow, so this might be a nice day to reflect on the Lancair Evolution.
This plane has almost no drag because of it’s clean shape, retract gear, and totally-feathering prop… in fact it can glide at a ratio of almost 20-to-1!!! This is starting to get kind of close to some gliders in glide ratio. The clean design, long, thin wings, and prop that can feather so the blades are perfectly aligned with the wind make this possible.
As well, as I have alluded to earlier, it climbs like a home-sick angel and goes like stink. (5,500 fpm climb, and can run along at 370 mph).
You already know it has only 3 computer screens for instruments, and may guess that the power that you can add for take-off is limited NOT by the engine power, but instead by how much RUDDER AUTHORITY you have to counter the torque! I have earlier mentioned, I think, that adding power results in significant ROLL from the power addition that must be countered by aileron. I have also previously mentioned that you are limited (by rudder authority) to specifically 550 hp for take-off, but can use 850 hp for climb and cruise (subject to air density lapse rate at altitude, of course).
Let’s talk about stability. The TAIL of an airplane only STABILIZES the airplane if it can dip down into air that is largely un-affected by the rest of the airplane. Think about it: If the plane is flying level and the tail suddenly dips down, the air, which is moving horizontally, simply pushes the tail right back up to where it was before, restoring the nose back down to level again! This is stability. BUT, imagine for a moment: What if, when the tail dipped down, the airflow was NOT horizontal, but instead aligned with the body of the aircraft??? The tail would have ZERO tendency to push back up again, thus restoring the plane to level flight! This is because the airflow over the tail would not change at all in this condition, so there would be no restoring force! The wings on ALL planes (except flying wings) help bring this unfortunate situation about… and a big prop blowing air (along the axis of the airplane!) helps contribute to this effect as well (in ALL single-engine planes with the prop in front.. but a bigger prop blowing more air makes the issue more noticeable). In other words, the huge power and prop of the Evo give incredible performance, but do extract some price in stability: The pilot must always fly this airplane, and not count on it to simply go straight, forever, by itself.
Also, airplanes with very TAPERED wings (wings that are narrow at the tip) have very little DAMPING in roll. Why? Because as the plane rolls, it is the air ‘hitting the wing from above or below’ OUT AT THE TIPS as the airplane rolls that damps out the rolling motion of the plane. The Evolution has very tapered wings. And the lower-damping effect is magnified at higher speeds and higher altitudes where the air pushing up or down on the wingtips as the plane rolls becomes small in comparison to the forward speed of the plane, and the air density drops… this results in very little damping compared to a slower, clunkier, certified airplane, so the handling is actually quite reminiscent of a helicopter! (which are among the SLOWEST craft flying!) Like a well-designed helicopter, the Evo is perfectly responsive and wonderful to fly, but very intolerant of inattention in flight.
844X has synthetic vision and artificial intelligence to find and display the way down after an engine failure… the Boeing 787 has NEITHER of these things in it’s avionics suite.
So the Evolution becomes a fascinating contradiction in (now out-dated) assumptions.
The airplane is the most COMPLEX single-engine prop that I know of… but it’s exterior shape is the CLEANEST and SIMPLEST that I have EVER seen.
Being a carbon fiber shell with a turbine engine, it is so light that the HEAVIEST single thing in the airplane is the FUEL it carries.
The plane goes like a bullet… but in the event of power loss, it glides like a glider.
It is the fastest single-engine prop you can buy… but it handles like a helicopter.
It has avionics that exceed a Boeing 787 in multiple types of sophistication… but it has not a single gauge on the panel.
It is certainly serious… but is flown with a joystick.
It contains a big jet engine… but is pulled by a prop.
The design elements above result in the following (in order of the above, line for line):
speed and safety
speed and efficiency
This is a pretty fascinating airplane…