Blackbird Sims / Milviz Forum Archive

After fixing my previous engine problems with setting up FSUIPC in a different way than everyone else seems to be doing (I have to set up Send to FSUIPC, no response if sending direct to FS), I'm wondering if the following two particullar engine phenomenon are realistic, a problem with the product, or just some gremlin on my side.

First off: On ground, advancing the throttles from idle, or retarding from higher power back to idle, there's a sweet spot a short travel above idle where the props starts to feather? I.e. idling at 1160ish, starting to advance slowly, the RPM rises, then dips to 1000ish, then rises again with further advancement, and vice versa. Autofeather, prop levers and conditions lever does not affect it. Video: https://streamable.com/a7nyj

Second: In the air, with props full forward, the torque is zero between idle N1 (~64%) and 80%. With props at 1500rpm, the torque reaches zero only very close to flight idle. While it could be normal, it seems odd to me that about half the power lever travel range is just zero % torque at max prop. Condition levers does not affect anyhting, as expected. Video: https://streamable.com/86qol

Hi,

meese91 wrote: ↑

Mon Feb 24, 2020 3:38 pm

First off: On ground, advancing the throttles from idle, or retarding from higher power back to idle, there's a sweet spot a short travel above idle where the props starts to feather? I.e. idling at 1160ish, starting to advance slowly, the RPM rises, then dips to 1000ish, then rises again with further advancement, and vice versa. Autofeather, prop levers and conditions lever does not affect it. Video: https://streamable.com/a7nyj

That is normal. In idle conditions (~ 63 % N1) prop angle is controlled by Ground Low Pitch Stop, which maintains rpms around 1100-1150. Once advancing power levers, after passing ~ 68 % N1 prop angle increases as it is now controlled by Flight Low Pitch Stop; this produces an rise in torque and a reduction in rpm that can reach as low as 950. Continuing with power lever increase, prop rpms increase as well, typically reaching 1100 again at ~ 73 % N1 and from there till max value of 1700.

Second: In the air, with props full forward, the torque is zero between idle N1 (~64%) and 80%. With props at 1500rpm, the torque reaches zero only very close to flight idle. While it could be normal, it seems odd to me that about half the power lever travel range is just zero % torque at max prop. Condition levers does not affect anyhting, as expected. Video: https://streamable.com/86qol

In flight, torque with N1 below 80% is really low, but not zero. That is going to be fixed in the SP.

Thanks!

Tomas

Thanks, that's all very good to hear!

I also notice that about every minute or so, when standing parked on the ground, the engines does a little dip in RPM, about 10-20rpm, noticed both on the engine readouts and aurally (so it's not just a flicker between two values, the prop actually goes down and back up), synchronously for both engines. Is this also to be expected? The only non-MV thing that comes to mind being cyclical like that with that frequency would be the FSUIPC FS/system clock second sync, but i didn't think it happened that often after having done it once.

That is a typical sympthom of noise on your joystick lever. It uses to happen also at 3/4 position, in some hardware.
If that bothers you, try adjusting the friction locks on the bottom of the console.

Sometimes it might also happens when the FMS is doing heavy calcs. That might affect the MFD thread for very short lapses, though won't affect FPS, so far I've noticed.

Tomas