DeMonteur Posted March 28, 2022 Posted March 28, 2022 In low alt approach to LZ when I put collective down with NOE/A channel of FMC I encountered strong pitch down moment when I slowing down under 80kt which I am unable to compensate even with full aft cyclic. I was able to recover it only with increasing collective. AH64strangePitchDownMoment.trk AH64strangePitchDownMoment2.trk 132nd vWing
IzeHouze Posted March 28, 2022 Posted March 28, 2022 From the docs... Is this what you are experiencing? Down Stab would cause a pitch forward with forward airspeed, I would think. (begin excerpt) NOE/A. Activates FMC nap of earth/approach mode. In NOE/approach mode, the horizontal stabilator is commanded to 25° trailing edge down when airspeed is below 80 knots. This provides better over-the-nose visibility for low-altitude flying. (end excerpt) 1
ED Team NineLine Posted March 28, 2022 ED Team Posted March 28, 2022 I'll take a look, thanks for the report. Forum Rules • My YouTube • My Discord - NineLine#0440• **How to Report a Bug**
Solution bradmick Posted March 28, 2022 Solution Posted March 28, 2022 When you go below 80kts the stabilator will schedule down to improve forward visibility, this is normal and expected behavior. This is also why I don’t like the NOE Approach mode. Manual stabilator is the preferred method IMO because you control it, and not the computer and you can better adjust the controls to control the pitch down that happens when the stabilator schedules. 2
ED Team NineLine Posted March 28, 2022 ED Team Posted March 28, 2022 Thanks Brad! Forum Rules • My YouTube • My Discord - NineLine#0440• **How to Report a Bug**
DeMonteur Posted March 28, 2022 Author Posted March 28, 2022 (edited) I know it pitchs down below 80kts. That is expected behaviour. Unexpected is that cyclic do not have on some occasions enough authority when you have collective full down to overcome pitch down moment from stabilizator. Edited March 28, 2022 by DeMonteur 132nd vWing
tech_op2000 Posted March 28, 2022 Posted March 28, 2022 7 minutes ago, DeMonteur said: I know it pitchs down below 80kts. That is expected behaviour. Unexpected is that cyclic do not have on some occasions enough authority when you have collective full down to overcome pitch down moment from stabilizator. If you trim the cyclic way forward with the trimmer, it will actually limit how much aft travel you have available. It may be necessary to initially pull it back a ways, retrim, then pull back more. This can be easily observed in the controls overlay RCTRL+ENTER. Pull it up, then add full forward cyclic on the ground and retrim. now pull full aft and see how far the controls indicator moves.
ED Team Raptor9 Posted March 28, 2022 ED Team Posted March 28, 2022 (edited) 1 hour ago, DeMonteur said: I know it pitchs down below 80kts. That is expected behaviour. Unexpected is that cyclic do not have on some occasions enough authority when you have collective full down to overcome pitch down moment from stabilizator. A rotor system's ability to change the attitude of a helicopter is proportional to how much total thrust it is producing. Redirecting this force vector relative to the center of gravity using the cyclic allows a helicopter to change it's attitude. At low power settings, you can still alter the attitude of the aircraft, but it may take substantially more input due to the weaker force vector. The stabilator is on the very end of a long moment arm, so even though it isn't a very large control surface, the aggressive deflection of this surface at the end of a long moment arm just below 80 knots can provide quite the force to counter with very little collective application. Even during a normal approach at lower airspeeds, slewing the stabilator trailing edge down requires a fair amount of aft cyclic adjustment to compensate. At 80 knots, you're really on the edge of the controllability envelope with a low power setting. I mean, the flight model is still work in progress along with everything else, but you're really pushing the intended use under these conditions. Edited March 28, 2022 by Raptor9 1 Afterburners are for wussies...hang around the battlefield and dodge tracers like a man. DCS Rotor-Head
DeMonteur Posted March 29, 2022 Author Posted March 29, 2022 9 hours ago, tech_op2000 said: If you trim the cyclic way forward with the trimmer, it will actually limit how much aft travel you have available. It may be necessary to initially pull it back a ways, retrim, then pull back more. This can be easily observed in the controls overlay RCTRL+ENTER. Pull it up, then add full forward cyclic on the ground and retrim. now pull full aft and see how far the controls indicator moves. I checked it with ctrl+Enter. I am just writing that even with full aft deflection on control overlay panel and full aft deflection with cyclic with low colective under 80kts I was unable to compensate the pitch down moment from stabilizator. You are then beyond the range of controllability. I find this behavior dangerous even for combat helicopter. Thats why I fill bugreport with tracks. Way to reproduce is turn on NOE/A mode in normal flight around 100kts. Then slow down with full collective down and under 80kts you are unable to compensate pitch down moment even with full aft cyclic. 132nd vWing
corbu1 Posted April 11, 2022 Posted April 11, 2022 I checked NOE/A mode on and reducing airspeed below 80 kts with low collective. At exactly 80 kts the AC‘s nose was diving down really hard. I was only able to recover because I was prepared what should happen applying full aft cyclic and pull collective…...interesting experience flying in VR…… DCS Version: 2.9.15.9408 Modules: UH-1H - SA342 - KA-50 BS3 - MI-24P - MI-8MTV2 - AH-64D - CH-47F - OH-58D - UH-60L(Mod, n.i.) - OH-6A(Mod, n.i.) - A-10CII - F-16C - F/A-18C - AJS37 - F-14 - MiG-21bis - JF-17 - Mirage F1 - MiG-29A - (prepurchase) - FC2024 -Combined Arms - Supercarrier - NTTR - Normandy2.0 - Channel - Persian Gulf - Syria - SA - Sinai - Afghanistan - Kola - Iraq - Cold War Germany — Waiting for: BO-105 - AH-1G/F(Mod) DCS-Client: 9800X3D, 64GB 6200, RTX3090, 1TB M2 NVMe(win10), 4TB M2 NVMe(DCS), VR VivePro2, PointCTRL, VaicomPro, Wacom Intuos S with VRK v2Beta DCS-DServer: 11600KF, 64GB 3600, GTX1080, 1TB M2 NVMe(win10), 2TB M2 NVMe(DCSDServer), DCS Olympus Simpit: NLR Flightsim Pro Cyclic: TM Warthog Grip with 30cm Extension + VPforce Rhino FFB FW Stick: TM Warthog Grip and Base, Throttle: TM Warthog Pedals: Komodo Sim. with Dampers Collective: VPC Rotorplus+AH-64D Grip Other: NLR HF8, Buttkicker (3*MiniConcert), TotalControls AH64D MPD‘s and EUFD, Alain Dufour’s AH-64 TEDAC, TM MFD, Streamdecks (1*32,3*15,1*6), VPC CP#1
NeMoGas Posted April 12, 2022 Posted April 12, 2022 (edited) The main issue I have with NOE/A is that in multi crew it likes to randomly enable itself even when neither crew has selected it from the utility page. I have had this happen probably 15 to 20 times as a pilot with a human CPG and another 15 or 20 as a CPG for another pilot. It usually results in near death but most times we recover. Unless this mode is supposed to enable itself automatically as some kind of brake check style awareness test lol. If so then it seems to be working as intended. If not then we have another desync bug to report. Edited April 12, 2022 by NeMoGas
bradmick Posted April 12, 2022 Posted April 12, 2022 It will only enable itself automatically if you select it on, on the UTIL page with the other FMC items. So if during run up someone is toggling it on (the circle is filled in) that’ll do it. Otherwise it doesn’t just come on. I’ve never once had it come on unless I’ve toggled it on. By default it is off on the UTIL page and has to be manually turned on.
NeMoGas Posted April 12, 2022 Posted April 12, 2022 Yeah I figured it would have to be manually turned on. I even check during startup to make sure it is off. Then at some point during the flight I will drop below 80 and the nose will pitch down. I then have to stabilize the helicopter and go into the UTIL page to turn it off. My CPG tells me he didn't touch it. I have also seen the same issue when I was CPG and I know I didn't turn it on.
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