PWM or DSHOT for a twin engine plane?

[RobertoD91]

Hi, I have a atomrc swordfish ( a twin motor plane), as far as I know with old version of inav there was issue using DSHOT instead of PWM, is this still the case in inav 8+?
I'm using a ATOMRCF405NAVI with stock esc, a generic 4S 30A with Bluejay 0.21.0 48kHz L-H-50.
I'm asking because I'm rebuilding the plane after a series of crashes and trying to figure out what I might have done wrong.

[sensei-hacker]

I'm not finding any mention of any Dshot problems with that board. DO you happen to have a link for reference?

[RobertoD91]

Sorry, I think I was reading some very old information (maybe from the INAV 2 era, like this: #4601 ), and also it wasn't related to my flight controller.
Just to be sure: nowadays there's no downside to using DShot, right?
Coming from betaflight, I naively assumed that 'DShot is always better', but maybe i'm wrong?

[sensei-hacker]

Sorry, I think I was reading some very old information (maybe from the INAV 2 era, like this: #4601 )

DShot is fine and good. DShot 1200 is silly. All down side and no up side.

DShot 1200 is still silly even on a racing quad. It's extra, extra silly on a Swordfish. How much do you think the speed of your Swordfish is going to change in 0.1 milliseconds? That's DShot 150. It takes 1/10,000 of a second for each update. Given the PID loop doesn't run that quick, even with DShot 150 it's sending the same value twice. Sending the same value 16 times (DShot 1200) is just goofy. There is no benefit to doing that.

[Jetrell]

Coming from betaflight, I naively assumed that 'DShot is always better', but maybe i'm wrong?

There is no issue with running PWM on fixedwing aircraft. Dshot doesn't offer any control benefits. Even with differential thrust.
Contrary to the main view. Dshot is not immune to the possibility of data packet corruption on longer cable runs between the FC and ESC. Especially if it runs past RF noise emitting devices and the wires are not twisted to reduce the effect.

The main advantage of Dshot for fixedwings is way telemetry is sent. But that too can be worked around with some ESC software's.

[RobertoD91]

Thank you all for the answers!

DShot is fine and good. DShot 1200 is silly. All down side and no up side.

Understood. I've never used DShot 1200. DShot 600 is the default for this plane: https://atomrc.com/pages/swordfish-1
Is that okay, or would you recommend switching to something else?

[sensei-hacker]

What I neglected to mention above is that faster the signaling rate, the more it is prone to interference. A signal that lasts less than 10 microseconds will be completely wiped out by 10 microseconds of interference. While a 100 microsecond signal will be immune to 10us interference. So that's why DSHOT 1200 is all down side, vs a more reasonable DSHOT rate.

An advantage of DShot over standard PWM or Multishot is that you don't need to calibrate the ESC.