Cessna 208B Prop Speed at Idle

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ISSUE DESCRIPTION

Description of the issue:

***DISCLAIMER: I know this was reported by another user then as resolved as not a bug a few days ago, but I’m pretty sure its a bug. The proposed resolution was that you have to feather the prop as to not windmill but it seems like more than that.

While in flight only (not on the ground), the Caravan prop speed will go crazy when power is brought below 20-30% or so. I un-mapped the binding to not allow my throttle to go into beta to make sure it wasn’t getting there while pulling the power back.

To test further, I would cut the throttle while flying level and then pitch up to bleed off speed. The prop winds out the whole time with the throttle at idle as if its under power. Furthermore, a full power steep dive with the prop set to max shows a prop rpm of 1975. But a shallow glide to land will wind out the prop to 2465 rpm as soon as the throttle goes below 20-30%. When its winding out, the aircraft doesn’t act is if it has full throttle but it’s definitely not low power or idle power. Makes it very hard to land properly.

Something seems way off with this one.

Feathering does work but you shouldn’t have to feather to land.

If applicable, which aircraft is experiencing this issue: Cessna 208B Caravan

[PC Only] Did you remove all your community mods/add-ons? If yes, are you still experiencing the issue? Yes

FREQUENCY OF ISSUE

How often does this occur for you (Example: Just once, every time on sim load, intermittently)? Everytime I fly the 208B, other users have reported this as well.

REPRODUCTION STEPS

Please list clear steps you took in order to help our test team reproduce the same issue:

  1. Fly
  2. Pull power below 20-30%
  3. Try to land

YOUR SETTINGS

If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

What peripherals are you using, if relevant:

[PC Only] Are you using Developer Mode or have you made any changes to it?

[PC, MSFS 2020 Only] Are you using DX11 or DX12?

[PC Only] What GPU (Graphics Card) do you use?
4080 Super

[PC Only] What other relevant PC specs can you share?
7800x3d

MEDIA

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[END OF FIRST USER REPORT]

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Do you have the same issue if you follow the OP’s steps to reproduce it?
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4 Likes
CL-415 flight idle bugged causing NP issues
3

It’s weird that’s it’s only at idle for you. For me, it’s definitely around the 20-30% mark, making landing very hard unless you feather which you shouldn’t have to.

1 Like
4

Same issue for me. Was a bit confused at first since this is my first flight sim but after reasearching the 208B I realised this definitely is a bug. As you noticed this is unrelated to airspeed so it makes no sense at all.

5

Thank you, a lot of people in the other thread say it’s the windmill effect or the throttle going into Beta. This issue is neither of those things.

1 Like
6

After researching how exactly these constant speed props work, I have some extra thoughts and maybe some advice for other new players like me struggling with the 208B (Maybe not entirely correct, as stated before, I’m new to this):

  1. When reducing the throttle to idle it is generaly correct, that the prop RPM is increasing, due to the oil pressure of the engine being to low to push the prop pitch further forwards.
  2. Still the landing config IRL for the 208B seems to be low throttle and prop level full forward, without having any issues with too high prop RPMs.
  3. IRL feathering the prop in the air is only required if the engine fails (To reduce prop drag and not lose as much airspeed). It should never be required to keep the prop from overspinning while in idle.

Since I struggled whith feathering the prop and giving it RPM again for reverse thrust after landing or for failed aproaches, I came up with the following procedure to land it:
Keep torque at 900-1000 during final with the prop and condition levers full forward as intended. Under full flaps with a 3 degree glideslope this should keep you at aproximately 90 Kts KIAS, which is usualy fine for landing.
If you’re coming in too high or too fast, either go around right away and retry a shallower glideslope or (if you can handle better than I can) temporarly feather the prop. Do not touch the throttle or condition to lose speed. (Obviously apply more throttle if you go around)
After touchdown you can use the throttle normally for reversing and taxiing.

7

That’s pretty much what I do for now. I find the threshold in the throttle just before the prop goes nuts. It still comes in hot though.

Gonna switch to something else I guess till it’s fixed. Which sucks because I really the 208B.

1 Like
8

Also note how during spinout event the torque has a negative value.

9

I’m saving for the Pilatus currently for the same reason.

when flying 208 though, I switched my procedures to just RPM redlining the prop anyways. Often times 90 kts is too fast and feathering the prop is too permanent (takes quite a long time to get it spinning again). So redlining it is the last resort.

11

Yes, I’m aware of the behavior of the plane being entirely unrealistic and illogical. I’m just attempting to provide possible workarounds.

Simply because I had several failed landings with the 208 (which are quite nerve wracking after flying a 3:30 Hr medevac carreer mission). So I’m testing around with different landing configurations in an attempt to work around this bug.

Main problem for me at first was the plane harshly pitching to the front shortly before landing when throttle is reduced to normal idle (not ground idle). This seems similar to your description of “as if reverse thrust is turned on at idle”. So we encounter the same problem, no worries. The game probably calculates the added drag of the propeller way to high under certain circumstances, which I still do not fully undrstand.

My first attempt was to feather the prop shortly before touchdown, to remove any additional drag it could produce. The obvious downside is having a long RPM build up period if power is required again (For reversing or go arounds). So this arguably made the issue worse for me because if there is a strong windgust while I’m 5 feet above the runway and I need to go around I can’t.

Then I attempted to land it at around 30% throttle to avoid this added drag situation. At first this worked fine for me and I trained it with a skydiving configured 208 in free mode.Back to carreer mode I was having a hard time even getting the plane onto the runway because no matter what I tried, I was too fast to land.

Currently I’m using around 10-20% throttle while landing which seems to be fine without the added drag and resulting pitch down. Also I tend to come in a bit too low for now, just to lose a couple of extra knots.

What’s certain is that the correct landing configuration (Throttle idle, Prop fully pushed forwards, high idle condition) does not work as it should, even though it is stated in the ingame EFB checklist and it’s used in real which I saw in a couple of YouTube videos.

(Anyone who knows more about this plane in real life please correct me if I’m wrong about the correct landing config stated above, I’m just a rather fresh flight simmer, not a pilot)

1 Like
13

From what I can make out the bug is that with the way most people have configured their throttles reducing the physical throttle to its minimum value puts the virtual throttle into beta range.

There is a further throttle bug where it is not possible to configure the range of physical throttle to include the whole range of the virtual throttle, i.e. not possible to engage reverse thrust.

For me, with the Thrustmaster TCA, flight idle is about half way into reverse thrust range on the physical throttle, and beta range starts nearly at full reverse thrust.

3 Likes
15

Indeed, there are two possible ways to bind the throttle axis, one with 0-100 and the other without the percentages. People for whom this issue is bad, could you try binding to the other one and see if it gets better?

1 Like
17

I really don’t think it is the way my throttle is configured. When I pull to idle, the throttle in the cockpit goes to idle. When I pull my beta lever the throttle, the cockpit throttle goes further back into the beta region.

1 Like
18

Could you check which profile your career c208 and your free flight c208s use?

When I bought a medical C208 it did not use the C208 profile I made until I changed the config manually - it seems to be treated as a different plane for profile selection purpose.

19

Can you take a look at the screenshots I posted above and confirm that we are talking about the same lever positions?

Do you see any difference in behaviour between what you refer to as idle throttle and what you refer to as beta range throttle?

20

That’s an absurd yet interesting observation. I was also practicing my landings in free flight and there it felt much easier to do than in career. I assumed it was due to me using the skydive configuration of the 208 (without the big box under the fuselage) while in career i use a medical config for medevac missions (WITH the big box under the fuselage). I assumed that’s why the planes felt so different.

Judging by the state this game and especialy career mode are in at the moment this might very well be an extension of the known weather/turbulence bug.

I might have to take a medical 208 for a free flight later today in order to fully compare them.

1 Like
22

Put the fuel condition lever in low idle, not high. You fly on low idle… you especially taxi in low idle otherwise you can almost take flight and will have to constantly be in beta

23

You do taxi in low idle, however the landing checklist specificaly tells to be in high idle during landing. That is also how pilots do it in real life as far as I saw. Also even though I’m using low idle, I’ll constantly be in beta while taxiing. There is a “ground idle” setting which is part of the beta range (at least it is ingame).

1 Like
24

Great showcase of what the problem looks like, this got me looking at what I also believe to be the culprit. I’ll reply here whit my findings since the other thread has been resolved.

My experience after some testing is that the throttle axis (whatever binding you’re using, including “Throttle N Cut”) in this plane is defined incorrectly and entering the beta range when it should in fact be flight idle.

The tool tip, and likely the “Flight Idle” definition is misleading in the sense that the throttle lever can be in a relatively large range of motion and always indicate “Flight Idle”. To visualize this you can set the controller’s throttle axis to 0 and then use the mouse pointer and wheel to go up and down on the throttle lever.

Doing this, what I observed is that you can go up one click and down one click while always reading “Flight Idle”. Going up will set the behavior to the expectation of actual flight idle and controlled RPM values.

actual_flight_idle
actual_flight_idle1445×1226 80.8 KB

Both of the lower “Flight Idle” positions will result in entering the Beta range and over speeding the propeller. The following picture illustrates the throttle axis at value 0.

throttle_axis_0
throttle_axis_01693×1305 90.9 KB

I understand this doesn’t directly answer the topic question but I believe it will help you track down the issue!

Extra info:
Looking at this comment, specifically at the propeller position it looks as if the dev team defined the throttle axis zero to be zero thrust and not the intuitive flight idle position

4 Likes
Caravan 208B - lowering throttle, propellor goes crazy
[MSFS2024] Cessna 208 B Grand Caravan EX
25

i think you’ve found the bulk of the issue. this echos what i’ve seen as well - very annoying - any chance you’ve played with a deadzone setting to mitigate this?

1 Like
26

Didn’t try that because my belief is that the dead zone is only for the input and thus should not prevent the axis value from reaching it’s 0 but do let us know your result if you try it!

1 Like