Strange pulsation effect on takeoff and landing

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Paughco
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Strange pulsation effect on takeoff and landing

Post Paughco »

Hi guys: I'm running P3D v4.5 and the only time I ever notice this is in my Spitfire Mk II (haven't flown the Mk I in quite a while, so dunno about that one). What happens is, during takeoff, I start applying throttle, and have the stick full back to keep the tail on the ground. As I'm increasing throttle, and as the airspeed gets up to 60 mph or so, I've pretty much got the stick neutral, or maybe a little down elevator to get the tailwheel off the ground (careful not to lower the nose too far, for fear of a prop strike). As the airspeed increases, and I'm getting the throttle in some more, I get this strange "pulsating" effect, which, looks like I'm rocking backwards and forwards in the cockpit. Once I get the airplane off the ground and cleaned up it stops. Until I'm on final, that is. When the gear and flaps are down, and airspeed is around 120 mph or so, it appears that the pilot is rocking back and forth about once per second or so. Almost like one of the things you see for hypoxia in some of the other airplanes at high altitude. Hmm. Maybe I'll put on oxygen and try it again.

OK, I tried it again, and it's the same with oxygen, and also the same in the Mk I. One thing I notice is that on landing I'm using quite a bit of throttle to keep the speed up on final with the gear and flaps down, and that's when it's most noticeable. Also, there's a lot of throttle during takeoff. It's not a really big deal, but I just wonder if that's the way it's supposed to be, or if I'm doing something wrong. It didn't do it when I first got the airplane, right after it came out for P3D, but I first noticed it after one of the most recent updates.

Thank you
ATB
Last edited by Paughco on 21 Jun 2019, 17:09, edited 1 time in total.
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Nick - A2A
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Re: Strange pulsation effect on takeoff and landing

Post Nick - A2A »

Hi Paughco,

Might be worth checking to see if the G effects are enabled in the P3D realism settings. I believe they can have unexpected side-effects sometimes.

Cheers,
Nick
A2A Simulations Inc.

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Paughco
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Re: Strange pulsation effect on takeoff and landing

Post Paughco »

Nick: Thank you for getting back! I have bad news and I have really good news. The bad news is that "visualize G-effects" had no effect whatsoever. The really good news is "visualize momentum effects" does it! Awright!! Now all I have to do is fix my "bump-sa-daisy" landings! :oops:

Thank you.
ATB
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einherz
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Re: Strange pulsation effect on takeoff and landing

Post einherz »

hi, this strange effect appear in new version of p3d in all aircraft, and only at low(below stall) speed, never mind what aircraft is, if speed below stall speed, this effect exist, when speed 0 or above stall speed - disappear, it's glitch and unreal, and must be will correct in next versions of p3d
p.s. i think in real life this effect could be real at static stable plane only, when start stall and aircraft go sink with nose up-down, only
rank is not classified airman - forum's engine glitch(again!)

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Nick - A2A
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Re: Strange pulsation effect on takeoff and landing

Post Nick - A2A »

Paughco wrote:
21 Jun 2019, 17:28
The really good news is "visualize momentum effects" does it!
Ah, good stuff - I knew it was something in the realism settings which seemed to cause a similar effect for me. As einherz says, seems like a platform-wide bug. The momentum effects in FSX/P3D have always been pretty ropey anyway, which helps to explain the popularity of add-ons like EZdok and Chaseplane.

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Nick
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patful
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Re: Strange pulsation effect on takeoff and landing

Post patful »

Paughco wrote:
21 Jun 2019, 17:28
The really good news is "visualize momentum effects" does it! Awright!!
Thanks for that! I've noticed some weirdness lately, and never noticed that entry. Off it went.

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whiic
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Re: Strange pulsation effect on takeoff and landing

Post whiic »

The pulsating glitch is also for FSX Spitfire, MarkI and MarkII (although I tested neither with wooden prop). I don't know if it was the latest update that broke it, or the previous one since I took a long pause from flying FSX.

Pulsating happens also above stall speed, up to around even 160mph when wheels are down. When wheels are raised, you can reach stall buffeting and there's zero pulsating nonsense. Also when landing, there's less pulsating than on take-off. Also, it doesn't seem to want to accelerate with wheels down. You need to firewall the throttle lever just to get it above 120mph... before updating, the speed had a tendency to climb rapidly if you leveled off after take-off, reaching speeds too dangerous to keep wheels down, even with modest 0 to +2 psi boost (full fine pitch, MK1). Now it needs +6 and barely gets out of stall buffeting and this weird low-frequency pulsating. And when wheels are up, it behaves like it used to, even cruising nicely at -4 psi boost.

I have a suspicion that the pulsating is an engine power glitch (or propeller efficiency glitch). Engine sounds normal during take off when inside cockpit, no misfire, no fluctuation in sound or rpm gauge. This is because in-cockpit sounds and gauges are created by Accusim and uses their own audio engine. External engine sounds are based on engine power that Accusim tells FSX while audio is played by FSX. And the engine sound fluctuates in external view with the same frequency as pulsating was visible in the cockpit view.

It would appear it has nothing to do with stalling or the flight model, but the modeling of the Merlin engine (or the prop) has broken during one of the later updates (probably the very last one). Power output when wheels are down is low, erratic and pulsating at about 1 Hz frequency. This glitch is such a weird one.
Last edited by whiic on 29 Sep 2019, 17:31, edited 2 times in total.

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whiic
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Re: Strange pulsation effect on takeoff and landing

Post whiic »

Edited the previous message to contain information from this post, so as to not state false findings or repeat same stuff.

Anyway, I haven't yet tried other A2A planes on FSX after the newest update, so I cannot tell of more than Spitfire is affected. Non-A2A planes fly normally. Problem is not limited to P3D.

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Piper_EEWL
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Re: Strange pulsation effect on takeoff and landing

Post Piper_EEWL »

patful wrote:
22 Jun 2019, 07:51
Paughco wrote:
21 Jun 2019, 17:28
The really good news is "visualize momentum effects" does it! Awright!!
Thanks for that! I've noticed some weirdness lately, and never noticed that entry. Off it went.
How do you turn that off in FSX? I can’t find it anywhere and that pulsating basically makes the Spitfire unflyable for me.

Thanks

Edit: fixed typo
Last edited by Piper_EEWL on 01 Oct 2019, 00:38, edited 1 time in total.
B377&COTS, J3 Cub, B-17G, Spitfire, P-40, P-51D, C172, C182, Pa28, Pa24, T-6 Texan, L-049&COTS, Bonanza V35B

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whiic
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Re: Strange pulsation effect on takeoff and landing

Post whiic »

Piper_EEWL wrote:
30 Sep 2019, 10:56
Gown do you turn that off in FSX? I can’t find it anywhere and that pulsating basically makes the Spitfire unflyable for me.
I don't know if it can be configured in FSX. These others have problems with P3D, and us two are using old FSX. FSX does have "G Effects" under "Realism settings" but I don't know if that has same meaning as "visualize momentum effects". Also, I'd rather not cut more features than absolutely necessary from FSX. (Removal of automixture, engine stress and airframe stress may be necessary for some addons to work properly. I just don't want to make the list of disabled features even longer.)

I wouldn't quite consider Spitfire "unflyable" but it's especially tedious to get off the runway as engine power fluctuates and is averages less than half of what it was prior to the latest update. It can barely get off the ground, and climbing above treetops takes maximum boost, even when taking off from commercial airports. There's no hope of taking off small grass fields anymore. It does seem to fly perfectly normal after wheels are raised, though.

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Paughco
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Re: Strange pulsation effect on takeoff and landing

Post Paughco »

I tried the Spitfire after downloading and installing P3D v4.5 with Hotfix 2. Same pulsation effect with "Visualize Momentum" box checked, but it goes away when the box is unchecked. I've got Visualize Momentum turned off for now, but a negative side effect of this is that my Civ P-51 no longer torques to the left when going through the runup. The top canopy frame would noticeably move relative to the monitor top during runup; greatly enhancing immersion into all that power. For now, I'd rather live without the torque effect on the P-51 in order to not have the pulsation effect in the Spitfire. Yeah, I guess I could rum momentum on for everything and turn it off when I fly the Spitfire, but I'm too lazy for that; I just leave it off.

It sure would be nice if some little glitch could be found and repaired in the Spitfire flight model, so that I could turn visualize momentum back on again!

Thank you
ATB
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MkIV Hvd
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Re: Strange pulsation effect on takeoff and landing

Post MkIV Hvd »

Piper_EEWL wrote:
30 Sep 2019, 10:56
Gown do you turn that off in FSX? I can’t find it anywhere and that pulsating basically makes the Spitfire unflyable for me.
To shut it off in FSX, edit the Cameras.cfg file in the: Users/"You"/AppData/Roaming/Microsoft/FSX folder. Change the camera 2 MomentumEffect from Yes to No:

[CameraDefinition.002]
Title = Virtual Cockpit
Guid = {C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}
Description = This is the description of the virtual cockpit view.
Origin = Virtual Cockpit
MomentumEffect = No
SnapPbhAdjust = Swivel
SnapPbhReturn = False

Hopefully that works for you. It does seem a strange bug though ... I'm using FSX:SE and don't have that issue with the Spitfire at all...... :?
Rob Wilkinson
A2A Harvard, Mustangs Civ & Mil, Spitfire, P-40, P-47, Comanche, Bonanza, Cub, VATSIM P2 and some other stuff...

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Piper_EEWL
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Re: Strange pulsation effect on takeoff and landing

Post Piper_EEWL »

MkIV Hvd wrote:
30 Sep 2019, 20:03
Piper_EEWL wrote:
30 Sep 2019, 10:56
Gown do you turn that off in FSX? I can’t find it anywhere and that pulsating basically makes the Spitfire unflyable for me.
To shut it off in FSX, edit the Cameras.cfg file in the: Users/"You"/AppData/Roaming/Microsoft/FSX folder. Change the camera 2 MomentumEffect from Yes to No:

[CameraDefinition.002]
Title = Virtual Cockpit
Guid = {C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}
Description = This is the description of the virtual cockpit view.
Origin = Virtual Cockpit
MomentumEffect = No
SnapPbhAdjust = Swivel
SnapPbhReturn = False

Hopefully that works for you. It does seem a strange bug though ... I'm using FSX:SE and don't have that issue with the Spitfire at all...... :?
Thank you. I’ll give it a try.

I also use FSX:SE and I only had this issue since the last update after the Bonanza. I flew some more yesterday and I can say that all three versions (MkI, MkIIa and MkIIb) have the same issue. And it’s weird because you can hear the effect when you switch to the external view. It almost sounds like the prop is cycling back and forth a bit but the rpm gauge doesn’t show anything.

I also agree that the Spitfire now feels a little bit sluggish after takeoff. But I can’t really proof that. Just a feeling.

I really hope someone from A2A can look into this and find a fix.

BTW my P-51 civilian shows the same behavior only not so pronounced as the Spitfire.
B377&COTS, J3 Cub, B-17G, Spitfire, P-40, P-51D, C172, C182, Pa28, Pa24, T-6 Texan, L-049&COTS, Bonanza V35B

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whiic
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Re: Strange pulsation effect on takeoff and landing

Post whiic »

Turning off momentum effect makes the bug just less visible rather than fixing the underlying problem of fluctuating (and reduced) thrust while gear is down. I made a backup copy of the persistent log and tried resetting it to new condition but it didn't help or worsen the weird behavior of the plane.

I'll just stick to flying other planes until this weirdness is fixed. Clocking more hours on B-17 since that doesn't share the Core Accusim, and is unaffected by this bug.

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Piper_EEWL
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Re: Strange pulsation effect on takeoff and landing

Post Piper_EEWL »

Yes turning off the momentum effect does mask the effect. But you can still hear it’s in the outside view. There’s definitely something wrong with the simulation there.

I really hope someone from A2A will look at this...
B377&COTS, J3 Cub, B-17G, Spitfire, P-40, P-51D, C172, C182, Pa28, Pa24, T-6 Texan, L-049&COTS, Bonanza V35B

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