cw4ogden

Is there a way to tune the FM band frequencies in the harrier, usually associated with the JTAC units, i.e. 30.00 Mhz range? Or, do you have to mission editor the JTAC unit to a VHF / UHF frequency to be able to communicate? Thirty minutes of searching here came up with no clear answer. Thanks in advance,

The forward is a given for forward flight, so let's just consider the left. I'm unsure if you are talking about a single rotor here, or still Ka-50? If we are still referring to the Ka-50, I think were it an airflow thru the rotor thing, you would see the phenomenon be highest at X on the forward flight envelope, and diminish as your speed increases. The cleanest air the lower rotor gets is at high speeds I would guess. In a single rotor helicopter that slight left cyclic requirement could be the result of most designs incorporating a few degrees of tilt into the main rotor mast to offset tail rotor thrust at a hover. In level flight that angle will create a slightly non-vertical thrust vector requiring a few degrees of tilt in the other direction, all but a trained eye might not notice. In the Ka-50 I'm fairly convinced it is because the retreating blades get pushed further into RBS than in a single rotor helo. I'd like to look up the rotor rpm and compute some tip velocites and see how they compare to say a UH-60. In the sim for me, about 280kph or 150 knots is where you are just flirting with disaster. That's just not as fast as I assumed it would be having never done the conversion to knots. I thought the Ka-50 was hitting 170ish knots in forward flight, but if it's more like 150. But 150 is fast for a helicopter. I don't think my previous assessment that the retreating side is generating no lift can be accurate if we are in the 150 knot range unless the rotor rpm is significantly lower than U.S. birds. But I think the overall explanation may still work. What does a single rotor helicopter do in RBS? It should want to roll left with an accompanying secondary pitch up caused by the rolling forces and precession. What does the Ka-50 want to do? It want's to roll into itself, basically. "Initial retreating blade stall symptoms include vibration, nose-up pitching, and a rolling tendency toward the side opposite the advancing side." Each side is just rolling towards the retreating blade, maybe?

I don't hold an aerodynamics degree, I'm just a fellow enthusiast with a different experience to draw on. My hope is I am not coming off as pretentious or as being a true expert. I enjoy the back and forth, and love a good rabbit hole so please take all speculations with a grain of salt. Transverse flow is a transient phenomenon unless you remain in that airspeed regime where the front portion is inducing flow to the back. Stay at 35 knots you will observe the moment in time captured by the picture in the illustration above. I'd guess the Ka-50 experiences it on the lower rotor longer into the forward flight regime, but still not a factor at velocities we are considering for the blade clearance question. Transverse flow in a 47 actually pivots you a bit about the pitch axis because instead of front half clean air, back half dirty phase lag fotor tilt, etc, in a 47 it becomes more front rotor clean back rotor dirty and the butt drops a bit, none of which you notice unless you turn off the AFCS, I think one area that's mixing things up is the difference between transient states and equilibrium states, and thinking of individual blades versus a rotor disk. Coning aside, I can't up flap in the front without flapping down in the back. Even when not aligned with the rotor head, i.e during blade flapping, the disk is still aligned with itself. It is still operating on a semi 2 dimensional plane. You can't flap up without an equal flap down 180 degrees later. The moment the torques aren't in equilibrium there is a yaw moment created. But either the pilot or the autopilot corrects by I believe a counter input of collective on each head, don't quote me on the lefty righty-ness of it but you start to fly forward, a force happens of your choosing that causes a differential torque between heads, you rebalance the yaw moment with pedal by an asking a little more power from whichever head for the direction you are starting to yaw around, and a little less from the other. Barring pilot correction you will reach another, different equilibrium which just means you are flying out of trim, and beyond what we are trying to navigate I think. An uncorrected minor yaw in a traditional helicopter should eventually get weathervaned nearly of existence in progressively faster forward flight, that would be the other equilibrium. It's not a coincidence. The lift you feel instantaneously is that you don't fall into a left(?) roll. The force we are compensating for being a loss of lift potential on the left side. The affect being a tilt to the rotor system in the form of blowback. The upflap and affect you feel at the 90 degree over the nose, the blowback, is the maximum displacement of the blades from the upward force imposed upon it by hitting faster oncoming air on the advancing side. The 90 degree point, also being the point by definition where it is no longer the advancing blade. So the cause of the force is also petering out progressively and ceases to be a factor at the 90 point. Either the blade flaps up and you feel the resulting tilt 90 degrees later, as the flapping mechanism corrects, or you push forward thereby lowering the pitch on the right, increasing it on the left which imparts its own phase lag adjusting forces in the opposite direction, re-righting of the disk. But if the lift, itself were happening 90 degrees in the direction of rotation, you'd still have the roll we are correcting to begn with, because you'd still have a dissymitery of lift.

If the top rotor's lift is greater, and it's torque more, you'd need to do the opposite. The top rotor moves clockwise, so it's torque alone would result in the fuselage turning left. To counter that you'd need right cyclic. Shouldn't any torque moments not being equal should result in a yaw moment? If the upper system began to require require less torque due to transition to forward flight, if I understand the rigging correctly, that would generate a movement about the X axis that would be countered by either increasing or decreasing collective pitch on the other rotor system, i.e. pedal correction? I'm asking, not dart throwing. The CH-47 does not exhibit this phenomenon where one system tilts right, the other left at high speeds. The point being if it were a matter of downflow from the upper system pushing the lower system around, or induced flow and unequal torque moments, I think we would similar on the 47. The coaxial design can really push beyond traditional retreating blade stall limits because one half of each disk, just isn't flying anymore, but until the mast snaps or the blades collide it just doesn't matter. The 47's design can't replicate this flight envelope without imparting immense twisting torsion forces because of lever principle. You can't get half of your lift up from from the front right and half from the left in the back without an immense twist, that would manifest as a roll as the two heads fight to keep things level and one can't keep up. I think whatever the specific aerodynamic combination of factors that explains it, the result is the aircraft wants to roll right due to the upper system being more efficient. The limit you are approaching is a left cyclic limit, which you can see by executing similarly loaded left and right banks at high speeds. For me it takes very little left cyclic at high speeds to make the blades collide. They could have made the separation between rotors further, to eek out a few more knots, but I'd be willing to bet the other sides of this physics problem is snapping the rotor mast. The blades hit first, but space them apart much more, and you'd go faster right up until the point you snap off the top rotor system due to bending forces.

This appears to be mixing up lift with maximum upflap. Lift across a rotor disk is at equilibrium, whether accomplished by flapping or feathering. The lift forces manifest instantaneously, the resulting up or downflap as a result of those forces occurs at the 70-90 degrees phase lag in the direction of rotation 70-90 being depending on blade count. Phase lag itself could use an explanation. Most people can wrap their heads around it but never understand why it occurs: When a force displaces an object, it will continue in motion until another force acts upon it. In our case the object is the advancing blade. In a nutshell, it happens exactly as newton would predict. The advancing blade has an upward force imparted upon it at the 3 o'clock position. It will continue traveling along that path upward until another force acts upon it, in this case the centripetal forces. The classic aerodynamics texts use an untethered ball passing by a blast of air. We wouldn't expect the ball's maximum displacement from the jet of air to occur at the point of air impact. It wouldn't jump immediately and instantaneously, at the time the force is imparted, it begins to move in the direction it was pushed. This is the same in a rotor system with the difference being at 90 degrees, it just can't go up anymore because it is tethered and has to come down. The ball is stopped by surface and air friction when it loses all momentum. A rotor goes up until it just can't go up anymore because centripetal forces pull it down. The 90 degree point is just the most a rotating body can displace up or down before being pulled in the other direction by centripetal force.

There is / was widespread disagreement on the terminology. Settling with power is vortex ring state per U.S. Army doctrine when I left, they are the same thing officially on a check ride, right up until the moment the IP goes off the record to have the conversation we are having. Why they call VRS settling with power I don't know. Maybe they just mish-mashed the two phenomenon at some point. We eventually and informally settled on the term settling with insufficient power to describe the phenomenon you are referring to. They are absolutely two entirely different things, though; one being an aerodynamic phenomenon, the other being a matter of excess downward inertia with not enough excess power available to arrest the descent. I feel the VRS is over-modeled, but it very well could be accurate. I'm suspicious, but never flew it to be able to say definitively. My evidence being the lack of a historical trend of VRS accidents in the MI-8. If it was as dangerous as VRS is in the MI-8 module, my supposition is there'd be a long list of VRS accidents. To me it feels, even at sea level, that you need the kind of caution that would be required only to operate at much higher density altitude conditions, or under much higher load. It is difficult to get an unladen helicopter into settling with power by accident. The MI-8 may have a quirk that makes this accurate, but it "feels" overdone. @volk Per the ka-50 other discussion: I am leaning heavily towards the explanation being a combination of the retreating blades completely unloading in the upper regions of the forward flight envelope, coupled with the lower rotors induced flow and inherent higher angle of incidence. I think what's happening is at high speeds is the two retreating sides are producing no lift or even negative lift. The resultant blade cones seen arise directly from the fact the two advancing lift vectors are competing to keep the aircraft level. In addition to blade collision, I would suspect the torsion force created on the masthead when the retreating blades unload is also an engineering consideration. The lower rotor is holding the right half up, the upper the left, and the resulting configuration at high speeds is just the lift vector required to keep things level. It is important to keep in mind a properly feathered rotor system is not experiencing any flapping due to dissymmetry of lift. Blade flapping is a transient phenomenon with regards to dissymmetry of lift. Also, I've read a couple times your supposition the lower rotor should experience a lower torque because it is generating less lift. I don't know that that is correct. Higher induced flow means more induced drag and therefore the lower rotor still generating less overall lift with equal torque applied.

I think the answer will elude us until that epiphany moment or a Ka-50 expert tells us the simple answer and we collectively go "duh". The good news being, your question is partially answered in that it appears, by all accounts to be accurately modeled, if maybe over-modeled. I have yet to make a post in the MI-8 forum because I have no first hand experience, but if vortex ring state was as dangerous as it is in specifically that module, there would be a lot of dead Russian pilots. It's a thing, yes. But you have to be a bit of an show off, be unfamiliar or operating at high density altitude conditions to get into it. The 47 gets a mushing like phenomenon that I'm convinced is aft rotor system getting into a vortex ring state on rapid decelerations or even a moderately fast downwind approach. If you are lucky you get told to put chinook on its side a bit if you have to emergency decelerate, but it was told to me as aerodynamic breaking with the hidden VRS danger being lost probably between Vietnam era and when I went through. I felt it once, and it scared the shit out of me. I would demonstrate the upper edge of VRS at a very high altitude hover for students, just so you could feel it. It is remarkably easy to get out of, if altitude is not a factor because you can dump the thrust and drop below the VRS portion of the velocity height curve, the autorotative upflow of air breaking the state, but you need I'd guess 200 feet minimum, and that's only a guess as the lowest safe altitude that's a viable recovery technique. And you still need to get forward or for 47's we go for sideward momentum, otherwise you will just wind up in the same flight regime, but from the bottom up.

Found this as well. It looks like it is modelled correctly. I just wish I could explain why. It is conceivable what's going on at high speed is the retreating side of both blades are straight up stalled from root to tip and only the advancing sides are providing lift. The resulting configuration arriving from each side's advancing blade trying to keep the aircraft from rolling. I wish I had a definitive answer.

Haven't read it yet, but I'll bet there's an answer in here. https://ntrs.nasa.gov/api/citations/19970015550/downloads/19970015550.pdf

The generation of lift is equal across the rotor plane. That is the flapping in action. If and when it stops being so that you will have pitch and or roll moments. What is clear is maximum upflap / downflap and minimum upflap downflap where they meet and why they don't parallel is modeled on the abeam points and that they converge. We know convergence is based in reality because there are documenting blade collision fatalities and the phenomenon was associated with high speed, minus any airshow type exceeding a normal flight envelope accidents. What we don't know is whether or not it is modeled accurately, or someone making the flight model applied a faulty explanation of the aerodynamics, specifically blew phase lag regarding blowback at high speeds. My gut says we just don't understand the correct phenomenon.

Volk, I am going to have to read and process your points, but I wanted to throw a few more thoughts out there. It's all too easy to get mixed up trying to figure out even a single rotor with the phase lag etc. I don't have a definitive answer for sure. We used to get the Boeing people on the phone and rarely was there ever a resolution to the more complicated questions. Here are a few other things to consider: 1. When flapping happens, it happens automatically as you probably understand. If you can picture a fully articulated rotor head, (semi-rigid is a different ball of wax), if the rotor head is angled at say 7 degrees nose low to the horizon, when you accelerate let's say with a very small amount of fixed forward cyclic: the blade flapping means the flapping hinges are being utilized and the blade tip path plane is therefore not aligned with the rotor hub, by however many degrees. But as that aerodynamic force takes affect, the pilot, by placing the cyclic further forward eliminates the blade flapping. Blade flapping is more a transient aspect of dissymmetry of lift. The point being you can chuck out a lot of the blade flapping blowback stuff because it is theoretical, you compensate for it as the pilot. In a single rotor helicopter I don't think it is possible to not compensate for it, you either push forward or the bird's new pitch angle returns everything to equilibrium regards flapping. In a chinook you can actually put the longitudinal cyclic trim switch in manual and just let flapping handle the dissymmetry of lift, but you get two rotor systems flying at different angles than the rotor hubs. It's why we have an airspeed limit for failed longitudinal cyclic trim of around 100 knots. You are approaching the limit where blade flapping isn't enough alone to counter-act dissymmetry of lift without severe aerodynamic stresses on the heads in general. To sum that one up: flapping is a transient mechanism. 2. High speed forward flight in a helicopter is limited by retreating blade stall and or what the army terms blade compressibility (supersonic). Of the two the compressibility is more dangerous because if you look at the pitch moment it induces, it will nose you down further. It is self aggravating. Retreating blade stall is somewhat self correcting. But either way, at the upper end of the forward flight spectrum, you are talking about one half of the disk barely breaking a sweat and the other half, only a small portion is still actually flying. The rest are in various stages of stall or even providing negative lift. Even if induced flow isn't a factor at high speeds, the lower rotor's higher inherent angle of incidence means it will stall sooner at the same pitch angles. My suspicion is the right side minimum clearance is because of the cyclic input countering the blade flapping coupled with the lower rotor either in dirty wind, or achieving critical AOA and stalling sooner. Retreating blade stall is a progressive phenomenon that works it's way outward on the blade. It happens in all but the slowest of forward flight. But the emergency or limitation that is retreating blade stall is when the phenomenon envelops so much of the blade no amount of flapping or feathering can keep the rotor head and aircraft hanging below it level. At high forward speeds, all but the very tips of the retreating blade is meaningless or contributing negatively to the equation. To summarize: I don't think blade flapping is the primary mechanism for what you are trying to understand. It is a phenomenon for sure, but it is eliminated by proper cyclic feathering. I toyed with the idea of putting all this stuff in a book and selling it to flight students. I went through flight school in 1999 and taught in 2006 and there was no tandem rotor aerodynamics class taught in 99, period. We just got the single rotor stuff and a guy with two more years experience than you telling you whatever garbage he heard. It boggled my mind how many wrong explanations there were for phenomenon that bird exhibits. I owe what I know to discussions like this with fellow aviators and just nugging through the physics then testing it out. Or you just have an epiphany one day and realize the reason the bird pitches down AFCS off when you pull thrust (collective) has nothing to do with whatever lie your AQC instructor told you and everything to do with the fact the forward and aft heads sit at slightly different angles and therefore equal amounts of collective produce a more vertical lift vector on the back rotor. There is an audience for this stuff, but it is likely small.

As a former CH-47 guy, we used to spend hours on discussions like this, rarely finding definitive answers. Tandem rotor aerodynamics is a bit of a unicorn. This guy has a fair explanation, but I am not sure I am sold. If I had to take a guess, I'd say you are confusing maximum upflap with minimum separation. Yes, the maximum upflap occurs over the nose from blowback, but the difference between minimum / maximum angle of incidence between the two blades would be highest over the right side. Throw in some induced flow from the top rotor system and I believe a higher base angle of incidence for the lower rotor system to compensate, and the lower rotor becomes the weak link in the chain, it has to play catch up with the upper, therefore the upper rotor at high speeds is generating more of the lift and the lower is just keeping things level? https://www.simhq.com/_air13/air_427a.html

Title says it all: the ECMD display remains illuminated after a complete shutdown. Maybe I am missing a switch, but If I understand correctly, the f-14 has no battery and therefore it's a bug? Thanks.

I've seen this a few times, most commonly after shutting down and attempting a restart: The right-hand engine starter switch / logic spools up the EGT instead of the N1. When this bug is present, the right-hand engine cutoff valve becomes very finicky, and can only be moved by clicking it in a very specific spot. No amount of switch-ology seems to remedy the bug, and the right engine will not start.

I'm guessing it's because I don't own the map. I assumed it was based on persian gulf or caucasus maps. Thanks. I'll try it after the next sale.

Trying to get the Afghan Bear Trap - Ka-50 campaign working for several hours now and I'm stumped. The firstmission.bat file works fine, I can see the files it creates, but DCS refuses to see them in the game's library. I've tried to open the individual .miz files in mission editor and I've copied and moved all the files generated by the .bat file all over the campaign directory tree with no luck. I would like to know what map it uses, and if maybe I just don't own the proper asset? Everything seems to work fine, with the exception of DCS recognizing any of the generated files. Thanks in advance. REM Core or Main DCS ou DCS.beta path, always end the line with \ set "pathDCS=D:\Eagle Dynamics\DCS World OpenBeta" REM DCS or DCS.beta saved game path, always end the line with \ set "pathSavedGames=Saved Games\DCS.openbeta" REM DCE ScriptMod version not any / or \ and no space before and after = set "versionPackageICM=20.38.01_S-AW" I have slashes \ at the end. The forum seems to be dropping them. camp.init updated the path to reflect dcs.openbeta in three places --path = "Saved Games/DCS.openbeta/Mods/tech/DCE/Missions/Campaigns/Afghan Bear Trap - Ka-50/", --path of campaign folder AfghanBearTrap.cmp updated various paths to replace users\david\ with my path. Thanks