Phantom Blipping

[Cynic_Al]

 

I can't find this mentioned in the technical section nor do I want to report it until I'm sure that I'm not alone in experiencing it.  On three occasions in multiplayer, I have heard the engines of some nearby rotaries sounding as though they are being constantly blipped about once per second.  Obviously the pilots concerned aren't performing such an action nor can they hear anything untoward with their own planes.  If I spectate the planes in question, in addition to hearing the audible blipping, I see continuous bursts of exhaust smoke consistent with a constantly blipped engine. 

While this misplaced effect doesn't affect aircraft performance, it can be disconcerting, almost creating the impression of being mocked by one's opponent.

 

Anyone else?

[No.23_Gaylion]

Yep.

[RNAS10_Oliver]

I think it’s maybe related to having their mixtures set full rich. Because IIRC have seen/heard it before on a pilot that I was on comms with, remarked about it and they then realised their mistake, sorted after adjusting mixture.

Edited April 30, 2021 by Oliver88

[Cynic_Al]

7 hours ago, Oliver88 said:

I think it’s maybe related to having their mixtures set full rich. Because IIRC have seen/heard it before on a pilot that I was on comms with, remarked about it and they then realised their mistake, sorted after adjusting mixture.

 

That occured to me but I couldn't trigger it on my own plane, so I'm still uncertain.

[RNAS10_Oliver]

55 minutes ago, Cynic_Al said:

 

That occured to me but I couldn't trigger it on my own plane, so I'm still uncertain.

Yeh do not think that occurs with your own plane with full rich mixture, but your viewpoint of others over multiplayer that have their mixture full rich. It’s not something have tested or whatever so maybe it’s also an intermittent thing.

[No.23_Gaylion]

AI planes do it.

[US41_Winslow]

26 minutes ago, US213_Talbot said:

AI planes do it.

The AI doesn’t know how to lean their mixture correctly.  They like to try to take off with their mixture full rich.

[Hot_Rod]

After running some tests in the QMB, I believe that this “phantom blipping” is a bug with the Nieuport 28 “throttle” function (I know - the Nieuport doesn’t really have a throttle, the engine speed is regulated by an ignition mode switch on the left side of the cockpit, that is tied to the positioning of your throttle device).

 

Normally, moving your throttle forward advances the ignition mode switch from position 1, to position 2, 3 and 4.  Moving the throttle back reverses this (position 4, 3, 2, 1).

 

I’ve found that if I fly with the ignition mode switch in position 3 for about a minute or so (as you would typically do to reduce speed in preparation for landing), the switch starts repeatedly cycling between position 3 and 4 (it sounds like the engine is being blipped, but it’s not really).

 

Reducing the throttle (even fully closing it) has no effect on the cycling.  Advance the throttle fully, and it will stay in position 4 (however, if you reduce the throttle again, the cycling will restart).

 

My assigned “blip” switch functions properly, but as soon as the blip switch is released, the cycling starts up again.

 

Needless to say, this makes landing the Nieuport pretty exciting!

 

I’ve found that - while coming in for a landing while the ignition switch is cycling - fully close the throttle, and keep the blip switch depressed enough to get your speed down, but keep the propeller turning (release it only for a fraction of a second at a time).  Continue to do this throughout the landing rollout, and when the plane has just about stopped rolling, you can release the blip switch - and now the throttle is functioning properly again!

[Cynic_Al]

1 hour ago, Hot_Rod said:

I’ve found that if I fly with the ignition mode switch in position 3 for about a minute or so (as you would typically do to reduce speed in preparation for landing), the switch starts repeatedly cycling between position 3 and 4 (it sounds like the engine is being blipped, but it’s not really).

 

The effect I described was noted on both the Camel and Dr1, but is only noticeable by other pilots;  what you describe may have another cause, but it will be some time if ever before I own the N28.

There's an account published somewhere in this forum, in which it states that on at least some N28s the sequencer switch was removed due to its use  being considered a fire risk.

 

 

[RNAS10_Oliver]

5 hours ago, Hot_Rod said:

After running some tests in the QMB, I believe that this “phantom blipping” is a bug with the Nieuport 28 “throttle” function (I know - the Nieuport doesn’t really have a throttle, the engine speed is regulated by an ignition mode switch on the left side of the cockpit, that is tied to the positioning of your throttle device).

 

Normally, moving your throttle forward advances the ignition mode switch from position 1, to position 2, 3 and 4.  Moving the throttle back reverses this (position 4, 3, 2, 1).

 

I’ve found that if I fly with the ignition mode switch in position 3 for about a minute or so (as you would typically do to reduce speed in preparation for landing), the switch starts repeatedly cycling between position 3 and 4 (it sounds like the engine is being blipped, but it’s not really).

 

Reducing the throttle (even fully closing it) has no effect on the cycling.  Advance the throttle fully, and it will stay in position 4 (however, if you reduce the throttle again, the cycling will restart).

 

My assigned “blip” switch functions properly, but as soon as the blip switch is released, the cycling starts up again.

 

Needless to say, this makes landing the Nieuport pretty exciting!

 

I’ve found that - while coming in for a landing while the ignition switch is cycling - fully close the throttle, and keep the blip switch depressed enough to get your speed down, but keep the propeller turning (release it only for a fraction of a second at a time).  Continue to do this throughout the landing rollout, and when the plane has just about stopped rolling, you can release the blip switch - and now the throttle is functioning properly again!

Have not seen that myself. I have had the throttle position cycling due to jitter on my throttle sending the percentage above and beneath the thresholds for the ignition states though.

 

As the Cynic states the phantom blipping is not an Nieuport specific problem. As the Camel has the problem. It’s the mixture on them. Never used the DR1 but does not surprise to learn that can see the problem in that also.

 

Tested again quick last night with @kotori87 as he was curious about the issue. I was in the Nieuport and moved the mixture to 100 and throttle to 4 and got close to him and he confirmed he could hear the problem (to start with could only see the problem until got closer). Then leaned my mixture out to an normal setting and the issue disappeared.

Edited May 3, 2021 by Oliver88

[Zooropa_Fly]

On 4/30/2021 at 10:03 PM, Miners said:

The AI doesn’t know how to lean their mixture correctly.  They like to try to take off with their mixture full rich.

 

I often lean before I start my run, but aren't we technically supposed to be at 'full rich' for take off ?

 

S!

[J2_Bidu]

1 hour ago, Zooropa_Fly said:

 

I often lean before I start my run, but aren't we technically supposed to be at 'full rich' for take off ?

 

S!

 

I start the engine at full rich, but take iff at max revs mixture setting.

[=IRFC=Gascan]

5 hours ago, J2_Bidu said:

 

I start the engine at full rich, but take iff at max revs mixture setting.

Same here. Must be full rich for the engine to start, then I lean it out to max revs for takeoff.

 

8 hours ago, Oliver88 said:

Tested again quick last night with @kotori87 as he was curious about the issue. I was in the Nieuport and moved the mixture to 100 and throttle to 4 and got close to him and he confirmed he could hear the problem (to start with could only see the problem until got closer). Then leaned my mixture out to an normal setting and the issue disappeared.

I don't know if he got video of it, but I can record some tonight and post it tomorrow. I'll check all the rotaries, and should have both the pilot view and the wingman's view. It seems like it should be very easy to reproduce.

[RNAS10_Oliver]

7 hours ago, Zooropa_Fly said:

I often lean before I start my run, but aren't we technically supposed to be at 'full rich' for take off ?

 

6 hours ago, J2_Bidu said:

I start the engine at full rich, but take iff at max revs mixture setting.

 

51 minutes ago, gascan said:

Same here. Must be full rich for the engine to start, then I lean it out to max revs for takeoff.

 

Ditto. As for the being in "full rich" for take off question, these snippets from articles seem to suggest that you do not need to do so, in the Camel at least. Though these are with regards to the Clerget 9BF and Bentley BR1 engines rather than the Clerget 9B that we have in our Camel.

 

Test flying The Shuttleworth Collection's Sopwith Camel F.1 (vintageaviationecho.com)

 

QUESTION: Ways to get killed in a Sopwith Camel? - Page 5 (theaerodrome.com)

Quote

After several turns of the engine the propeller is turned back to a position of about 10 o'clock: then the mechanic shouts "Contact!" The pilot puts both switches ON, the petrol fine adjustment lever nearly right back, the throttle half open '1lnd shouts "Contact." The mechanic pulls the prop' down smartly; and in turn has his arm or belt pulled hard by the rigger to get him clear of the propeller as the engine fires.

 

Quote

Taxying: One of the pleasing features of the B.R.l engine in comparison with earlier makes is that it responds normally to the throttle and does not require "blipping" although a blip-switch is provided in the spade-handle of the joystick. So the initial engine run-up to give 1,050 revs can be done by opening the throttle and petrol fine adjustment lever together.

 

Quote

Take-off Check for 1tlb/sq in air pressure in the pipe to the air space in the main petrol tank: this can be corrected by adjusting the relief valve in 'the pipe near to the pressure gauge or by pumping air with the hand pump near to the right hand. Look to see that no other machine is coming in to land: pull down your mask goggles; open the throttle wide and simu1taneously move the fine-adjustment lever just past the half-way position on the quadrant, when your ear will tell you that the mixture is correct and the engine firing evenly.

 

 

Edited May 3, 2021 by Oliver88

[Hot_Rod]

 

15 hours ago, Cynic_Al said:

The effect I described was noted on both the Camel and Dr1, but is only noticeable by other pilots;  what you describe may have another cause, but it will be some time if ever before I own the N28.

Hi Cynic_Al,

 

I think you are correct - that the issue I described is a separate issue.

 

I’ve submitted a bug report on the issue I described, and I’m thinking of starting a separate thread on this issue (I’m curious if others are experiencing this as well).

 

My apologies if my post side-tracked the thread, or confused anyone about the issue that you’re trying to resolve.

 

 

Rod

[Cynic_Al]

1 hour ago, Hot_Rod said:

 

I’ve submitted a bug report on the issue I described, and I’m thinking of starting a separate thread on this issue (I’m curious if others are experiencing this as well).

 

That's fine as long as you have actually eliminated the suggested possibility of a spiking throttle control.

[Hot_Rod]

2 hours ago, Cynic_Al said:

That's fine as long as you have actually eliminated the suggested possibility of a spiking throttle control.

I’m pretty confident that I’ve eliminated that possibility (checked the control responses - used the “-“ and “=“ buttons for throttle control - deleted the throttle control from my primary joystick (Logitech 3D Extreme Pro) and assigned the throttle from a different joystick (Thrustmaster T16000M)).

Each and every time the cycling started up as I described in my original post.

[=IRFC=Gascan]

I just did a bit of SCIENCE! and have a bit better idea what may be going on. On all the rotaries (N28, Camel, and Dr1), if your mixture is very very rich and the throttle is full, the engine RPM will drop a bunch and start bouncing around. Anyone flying nearby will hear a sound effect of blipping, combined with a small puff of smoke from the engine. Lean it out, and it goes away. I have not tried it with mixture full rich and throttle reduced. I recorded both my perspective and Kotori's perspective while testing all three rotaries for both the mixture and with actual blip switch for comparison. Since this happens on all three rotaries, I suspect it's behaving as intended, perhaps modeling something for running very very rich that I'm not aware of. After all, I am an expert on steam turbines, not century-old internal combustion engines.

On a separate note, the N28 engine sound doesn't actually change with the RPM of the engine, but the Camel and Dr1 do. If you adjust throttle, the engine noise changes just fine on all three rotaries. If you lean out the mixture but keep throttle at full, the RPM drops on all three rotaries, and the engine noise changes for the Camel and Dr1. The N28 engine noise stays the same, even when RPM is significantly reduced. Since there is a difference in the behavior of the N28, I suspect there may be an actual issue there (engine noise based off the throttle position rather than the actual RPM). I'll post the video tomorrow, once I figure out how to show both my view and Kotori's view side-by-side, and probably also make a bug report for this second issue.

[=IRFC=kotori87]

Correction to Gascan's post: the N28 engine sound appears to be driven solely by ignition switch position, 1, 2, 3, or 4. Put the ignition switch in full position, you get the full throttle noise, regardless of RPM. Put it in a reduced position, and you get a reduced-ignition noise, again regardless of actual RPM. I'll give Gascan a poke about submitting a bug report about that.