cw4ogden

What is the load you are trying to carry? It might be intentional as long enough loads will interfere with the radar altimeter. M198 155mm howitzer is notorious for doing this as the barrel sits directly under the radar altimeter antenna. Is it no longer working? I.e. off? Or just indicating an incorrect altitude?

I'm with @Brickle on the sound. It's damn near perfect. It was giving me big time hits of nostalgia. If I turn on Bob and close my eyes, I can pretend I'm nodding off in the real thing.

It is, in fact wrong. The NORMAL shutdown procedure does require the APU and APU generator. But the APU/APU GEN do not need to be running to shut the engines down. This can be proven with some logic, as the emergency engine shutdown procedure does not task the pilot with starting the APU first. The APU is started primarily to maintain electrical power and flight control hydraulics during the shutdown. The FADEC system uses a built in alternator to power the FADEC in a complete loss of power. So shutting down with no APU generator the pilot should see a complete loss of electrical power, around 85% rotor rpm, with the battery remaining as the only source of electrical. The engine shutdown should still proceed normally, as the FADEC powers itself, even without a battery installed ***. In real life, the FADEC primary stepper motors can not completely close the fuel valves. The FADEC backup system (reversionary mode) secondary stepper motors are the only way to completely stop fuel during shutdown. Therefore FADEC backup power MUST be on, or the engines will receive enough residual fuel to damage the engine, and keep the rotors spinning at a low but steady speed. This is why with a FADEC primary failure, the procedure to shutdown the engines includes pulling the "fire pull" handle. I haven't had an opportunity to test it, but ensuring the FADEC backup power is on, would be the obvious fix to the OP, if the system is accurately modeled Will do some testing and report back. To the other point raised about rotor coast down time: as is, it is unrealistically long. *** Anecdotes: Through a comedy of errors, I watched this FADEC phenomenon unfold twice. The first was a junior PC who torched an engine on shutdown with a primary FADEC failure. The command grounded him, and threatened to hold him financially liable for the entire 1.2 million dollar price tag. Not joking. At the time we had no procedure for this and assumed the primary system could shut down the engine just fine. Why wouldn't it? I dug up the Service Bulletin Boeing had sent the Army detailing the problem, the Army never implemented, and he was off the hook. Two days later an Army wide pen and ink change to the checklist came down, creating an entirely new emergency procedure - Engine shutdown with a FADEC light. The other, a neighboring crew chief had "borrowed" his neighbors battery without informing the crew. Their bird sprung a hydraulic leak, and upon performing an emergency engine shutdown, they lost all power to include the missing battery power, and therefore intercom. All would have been fine, except they missed turning the FADEC backup power on during runup. Both engines glowed red hot for about ten minutes with the rotors continually turning, maybe 5-15 rpm. We eventually dispatched our crewchief to go pull their manual fuel shutoff handles, as the pilots were baffled up front, and focused why the now inoperative fire pull handles weren't helping. Their flight engineer almost certainly knew what to do, but without an intercom, he had no idea what was happening.

Reading deeper into your question, I see my answer falls short of answering your example. In pitching forward, I.e. Reducing pitch / torque on the forward head, and increasing it on the aft head, it does seem like it should induce a yaw. The effects in your example would be additive, and not cancel each other out was my mistake. But as Brickle said, it doesn’t manifest to the pilot. I can hypothesize why it might work that way, but the fact is there’s little to no yaw / pitch coupling. And at the moment I don’t have a good explanation why. My guess would be the forces are there, but where a single rotor helo is the pivot point and is only twisting a small moment, I.e. the tail rotor section, in your example the aft rotor is trying to turn a huge moment, the fuselage and entire front rotor head. So it becomes un-noticeable. Best guess.

Most rotor related phenomenon that produce yaw tend to get cancelled out because of the opposing rotation of the two rotors. If one head wants to yaw left, the other wants to yaw right and the forces work to "bend" the helicopter, which thankfully bends very little.

@Brickle Thank you for the kind words. If you were involved in the testing for DCS I'm pretty impressed with the product so far.

@Vee.A Best I recall you largely don't hear it up front barring a maneuver like a 60 degree sustained turn. And even then it's going to be a slight change in noise up front. My opinion of the sound is it's actually really good. I'll give a listen, but barring the APU being a little quiet, currently no avionics cooling fan, and no power transfer sounds, what's in place sound wise sounds really good to me. It sounds like being in a chinook

Hey I posted a long thread in the Wishlist, most of it for DCS but my last point is something every 47 driver needs to know regarding a little known pitfall of the FADEC system being put into dual reversionary by tailwinds, or tailwind component as a result of rearward flight / drift. It may no longer be a problem but if this sounds like something you've never heard of you should read the part I put a bunch of asterisks by.

@NineLine Apologize for the ping, and my longwinded nature, but as opposed to making a bunch of bug reports I would like to combine several topics into a more wish-list like thread. Things it would be awesome if the DCS FM happened to mimic. A to be passed along to whomever kind of thing. Rotary wing aerodynamics, being akin to voodoo is a not well understood science. Tandem rotor aerodynamics is arguably much less understood, often even by those who've learned to harness it. This is meant as a collection of little understood phenomenon attributable to the tandem rotor configuration. Not an insult to anyone's intelligence, or assertion that these are the 100% factually accurate causes. These were the best explanations why the CH-47 did what it did. It would be nice if the flight model had some of the quirks the real aircraft does, and for that to be possible a thorough understanding of how tandem rotor differs from a conventional helicopter is necessary. Most if not all of these happen AFCS on or off, the only difference being who is counting the phenomenon, the pilot, the computer, or a blend of both? I can speak intelligently on the underlying aerodynamics, but your contemporary SMEs will have to speak on how the digital AFCS handles them from a pilot's perspective. The discussions will focus on AFCS off flight, and leave how the DAFCS handles, to your more qualified individuals. I hope only to fill in any gaps in institutional knowledge. Difference in angular tilt of the fore and aft Rotor heads. As mentioned in my other thread, the difference between the angular tilt of the fore and aft head causes any movement of the thrust to manifest in an immediate and linear pitch change. This linear change in pitch can be exasperated, as can any transient in a negatively stable system. Said another way, while the cause of this phenomenon is linear, if not reacted too quickly it can exasperate itself. One of the more noticeable regimes of flight this rears it's head is the roll on landing. AFCS off roll on landings often require the pilot to need forward cyclic during the flare portion when thrust is reduced. This is counter intuitive to most pilot's muscle memory, and is the primary hurdle to pulling off a decent AFCS off roll on. Another is doing precision hovering with significant changes in altitude, i.e. taking slack during a sling load or any vertical climb / descent such as masking. The chinook wants to drift forward when you pull thrust, and drift aft when you reduce thrust. It just does. The extent to which the newer AFCS compensates is what I can't speak to. Vortex Ring State / Mushing The CH-47 is one of a handful of aircraft that lightly loaded has enough power to pull itself out of VRS, theoretically. It will get into VRS, but it is not particularly prone to it like one might think. The dual rotor system tends to give the pilot a little more warning than in a single rotor helicopter, as the induced flow moves progressively from back to front, it engulfs the rear rotor first (assuming decelerating flight). The preferred method of recovery is lateral cyclic, as forward cyclic can aggravate the problem due to differential collective pitch increasing angle of incidence of the aft rotor system. In 15 years of flying chinooks I never encountered VRS, unless I was showing it to a student. Nor do I know of a single VRS accident in the community. A much less well known pitfall is the phenomenon akin to mushing where the AFT rotor head can achieve a Vortex Ring state during rapid decelerations. This manifests in the an abrupt nose up and transition to a sinking attitude of flight which if not recovered from quickly, for will result in a hard landing at the least. Of these, there have been a handful or more. This is the exact same phenomenon that is responsible for V-22 osprey crash(es). It happens to them in tight descending turns due to their horizontal tandem configuration. Transition to forward flight / Transverse flow effect When picturing how a Chinook reacts to transverse flow effect, it's useful to use a simplified understanding of fore and aft head, acting in unison and ignore the effects on each individual rotor system. Looking at it as an oversimplified combined rotor system, Transverse flow effect manifest to the pilot as a slight nose up while transitioning forward through ETL. The AFT rotor system ingests "dirty" air first resulting in a few degrees of pitch up, resulting from the tail wagging the dog, so to speak. The individual rotor systems are affected, but due to their counter rotation nature, the force created is a twisting, torsion force absorbed by the fuselage. The pilot feels the back end sag accelerating through ETL, and the reverse when slowing to a hover. Retreating Blade Stall / Blade compressibility The forward speed of a CH-47 is limited by one of two phenomenon, retreating blade stall, or the advancing blade approaching supersonic flight regimes, referred to for physics reasons as blade compressibility. If you again look at the CH-47s two rotor systems as a single system you will be able to predict the results. Retreating blade stall tends to be somewhat self correcting as it induces the aft head to lose lift first. Blade compressibility tends to self aggravate for the opposite reason. Either may or may not be accompanied by rolling transients. Dissymmetry of lift / LCTs Due to the tandem rotor having no inherent ability to cyclic feather, a system is needed to compensate for dissymmetry of lift. This system is of course the longitudinal cyclic trim system. Up until a certain airspeed, cyclic feathering is unnecessary. The system can compensate via blade flapping alone. But the direct result of blade flapping is rotor blowback, and beyond a certain point, you begin to put excess strain on the rotor heads and may encounter droop stop pounding in flight, or worse. The other often overlooked role of the LCTs is the level the 47's fuselage at a hover. This was a necessary change with the addition of the triple hook cargo system. The fuselage needed to be level for ground crews to reach fore and aft hooks. Prior iterations of the 47 hovered significantly nose higher, (I'm told). Weathervane effect a.k.a. the CH-47 Rodeo While I never experienced this personally, a CH-47 AFCS off will do a 180 degree turn, in cruise flight if you let the yaw get away from you. This is just a simple combination of whether vane effect and the subsequent induced yaw inertia. If you let the nose get between what I'd estimate is somewhere between 20 to 30 degrees, you will be going 100 knots in reverse before you know it. *** For anyone active in the CH-47 community - important *** Beyond the scope of a DCS discussion but for any active 47 people this is a phenomenon you need to be aware of. Any excess rearward flight, or significant tailwinds at a hover can trip your DECU temp mismatch logic causing you to suddenly be in dual reversionary FADEC mode. While this may sound fairly benign, it is a nasty little demon of the 714 engines that can kill you. If you haven't heard ever been made aware of this, you really need to know about and understand it. As the reversionary can't sense rate of thrust movement, it is designed to over/under program fuel, to mitigate rotor droop, or overspeeds during thrust changes, while operating in reversionary mode. If this happens, to you, you will get a master caution and dual FADEC failure indications, caused by the temp probe in the rear of the engine disagreeing with the one further inside. If you happen to be making a power change, this can very easily look like a dual engine runaway, or a dual engine power loss depending on which way the thrust was being moved. It can trick the pilot / crew into thinking they have an engine high side, and make the problem worse by pulling more power. Or if encountered when reducing thrust, be tricked into thinking both engines suddenly rolled to idle and auto rotate with two perfectly good engines. This phenomenon, has Induced at least one unnecessary autorotation, a crew who had this happen and believed both engines had rolled to idle. And I had the reverse, the high side experience once, and thought my engines were going to spin the blades completely off as the overspeed fuel control held the rotor RPM at 114, overriding the FADEC hell bent on killing us all. I'll leave it at this for now. If this is well received I can probably drudge up more. A pilot can often operate fine at an application level of knowledge. Meaning, if I know the nose pitches up when X happens, I don't necessarily need to know why. But with understanding comes the possibility to achieve the next step in learning correlation, or spontaneous learning. When you learn something new, on your own, because of the various things you took the time to "understand". It's when you have that epiphany moment and it all makes sense. A pilot who rests firmly in camp understanding, or even better to correlation, can anticipate. A pilot who only makes it to the application level, can only react.

Yes the basic functions of the AFCS like pitch attitude hold, bank angle hold, heading hold (not heading select) are ILCA functions. So can't blame dash or LCTs. I've got another thread on what the 47 should do AFCS off, specifically how it rotates about the pitch axis with changes in thrust. It's caused, best explanation I ever came up with is from the unequal tilt of the fore and aft heads. The aft head sits a few degrees more vertical, but it's enough that equal "collective" amounts of pitch cause the aft head to generate more lift than the front. So pull thrust, nose down. Reduce thrust nose goes up. That phenomenon is or was rarely understood and it manifested with the AFCS on too, just much more subtle. Most people had any number of explanations, but chinooks pre-digital AFCS so D not F model, had a tendency to drift forward when adding power at a hover and drift back when reducing. Can't say if that drift AFCS on persisted to the F, but the AFCS off characteristics definitely didn't change.

It may help as a work around while they iron out bugs, but shouldn't be necessary or even beneficial. LCT's just tip both rotor disks into the relative wind in forward flight. It's the equivalent to pushing the cyclic forward in a traditional helo, but it happens on both heads, so you get a more level fuselage at high speeds, and reduced blade flapping. Thereby Increasing the top speed you can attain before hitting retreating blade stall as well.

Hovering flight feels good. Forward flight both AFCS on and off need a lot of work still.

Yes, can confirm AUX tanks do not transfer fuel for me either.

Crossfeed stays closed during normal operations to prevent the possibility of a dual engine flame-out. If you suck one side dry, having the X-feed open will flame out both engines. The best analogy is having two straws one in your glass, one inside your drink, the other outside of it. If you suck on both straws, you're only going to get air. Given the choice, with the crossfeed open, both engines will draw from the empty tank akin to the straw sucking air. As depicted in your photos it appears to be a bug. Aux's feed the main tanks keeping them topped off until Aux tanks are empty. Will test here as well. Keeping the crossfeed closed, fuel starvation can only kill the affected side's engine.

Stryker exceeds what a CH-47 can lift by a factor of 2. It's twice what you can lift weight wise, about 18,000 pounds as a rule of thumb at sea level - full fuel. Stryker weighs ~36,000 lbs. Also hoisting is different than sling loading. The hoist is used to pull cargo up the ramp or lift a survivor through the cargo hole in the floor. In hoist mode you're limited to 600 lbs. So hoisting and sling loading are two different things.

I don't know if it's modeled, but the FADEC back-up power needs to be on to shut down the engines, as the primary system cannot completely stop fuel supply.

3-5 seconds in the middle (run) position, seems closer to 5. hold in start position for 2 seconds.

Yes, I'm aware. I took that to mean either more features possibly, or more tuning. If it's just more features, this is a bug. If it that this a work in progress, can't hurt to get it on the record. Once trimmed, with the AFCS on, the pilot should able to take their hands off the controls for extended periods of time.

AFCS on flight is far too erratic, primarily in the pitch axis. AFCS on should look more like how the aircraft flies with "Bob" turned on. A trimmed out CH-47, with AFCS on, should require no significant inputs from the pilot in flight, even with significant changes to the thrust. Not trying to throw darts, just document what I see. My initial impression of the flight model is that it is a very good starting point. The flight modelling "feels" very close.

Thrust (collective) inputs should make significant changes to the aircraft's pitch attitude AFCS off. Pulling in thrust should cause a pronounced nose downward moment. Reducing thrust should cause the nose to pitch upward. This is caused by the fact the forward and aft rotor system are mounted at different angles. 9 degrees of forward incline on the front, 4 degrees on the aft. This angular difference causes the aft rotor's lift vector to be more vertical than the forward system's, and therefore any change to collective pitch will add more lift to the aft head than the forward head, and vice-versa. The difference in lift vector manifests in a rolling moment about the pitch axis. Pull thrust, nose goes down, lower thrust, nose comes up. The same aerodynamics happen AFCS on, but are largely (but not entirely) mitigated by the AFCS.

Bankler's is a useful tool, pre-installed on a few servers that may help too. A few servers had it in their name or description making it searchable, don't know if that's still the case. I personally think learning case 3 recoveries first is the way to go. Case 1 recovery is one of the hardest tasks in DCS, rivalled only by air to air refueling. Learning the case 3 intimidates most, because of the bookwork to understand tacan, but it is a much smaller stepping stone, to go from case three approaches to then mastering the case 1.

A real life technique for judging turns to line up with a runway is to keep your focus on the far end of the runway. Why it helps I don't know. Granted on the carrier this requires some imagination. I picture an imaginary runway running forward of the boat. I make corrections to arrive over that imaginary runway, not focusing on the "approach end" but keeping my eyes trained on the far end of the imaginary runway, an imaginary point somewhat forward of the boat to account for the fact the carrier's landing area represents a small portion of a normal runway. An imaginary point in space 5000' or so in front of the boat in line with the landing heading. Fudge a bit to account for boats forward motion, which obviously complicates it some, but the principle of looking at the far end of your landing area is known to help pilots judge turns to final. To apply it to carriers requires a little imagination but may help. edit: you are indeed, way too high to see the ball in the screenshot posted. a 3 degree glide slope means your landing area should barely be below the horizon. Roughly three degrees. I'd guess to make the 3 wire from the point you are in that screenshot, you'd need a 10 degree or more glide path angle. Well beyond what the ball can display.

@gonzolofogous Mast bumping almost always implies a negative G situation. Best way to visualize mast bumping is to picture pushing your rotor shaft upwards into a tilting see saw. If you push hard enough, the rotating see saw eventually will tilt enough that it contacts the rotor shaft, aka mast bumping. What I see in your video appears more like some kind of structural failure. I guess that could be how they have mast bumping coded, but I'd suspect over G or some kind of other limit being broken. If your G loading is above Zero, as it looks in your video, it's almost certainly not mast bumping.

I think it predates this patch. You can try F8 groundcrew, then i think f9 request launch, occasionally it works. But once the ground crew bugs out, probably need a server reset to fix it.

Ok will do. That seems the most plausible cause.