ChockP51 Posted July 17, 2019 Posted July 17, 2019 (edited) This is a bug I noticed some time ago. Not sure if someone mentioned yet. Basically when I fly low and fast in the transonic region with a wing manually swept full aft and autopilot engage in altitude hold, the autopilot will command a high-frequency roll oscillation. If the heading mode is engaged, no roll oscillation will occur. Here is the video. Best regards. Edited July 18, 2019 by IronMike
Strikeeagle345 Posted July 17, 2019 Posted July 17, 2019 I have noticed this as well. Strike USLANTCOM.com i7-9700K OC 5GHz| MSI MPG Z390 GAMING PRO CARBON | 32GB DDR4 3200 | GTX 3090 | Samsung SSD | HP Reverb G2 | VIRPIL Alpha | VIRPIL Blackhawk | HOTAS Warthog
jmarso Posted July 17, 2019 Posted July 17, 2019 If you're in the transonic regime, aren't you outside the normal speed 'envelope' for the autopilot? (I'm not trying to be sarcastic- I don't actually know the hard limit myself. But it seems like you would be.)
ChockP51 Posted July 18, 2019 Author Posted July 18, 2019 If you're in the transonic regime, aren't you outside the normal speed 'envelope' for the autopilot? (I'm not trying to be sarcastic- I don't actually know the hard limit myself. But it seems like you would be.) Well strictly speaking, the oscillation is in the region of subsonic toward transonic. Furthermore, the autopilot work fine near sonic speed ie around Mach 0.9. Besides it would seem like a major drawback consider that major airliner and jet cruise at transonic speed.
sLYFa Posted July 18, 2019 Posted July 18, 2019 I didn't find any speed limitation on autopilot usage in any of the RW docs or HB's manual. I do seem to recall though that at high supersonic speeds, the autopilot (or just SAS? can't remember) starts to create roll oscilations. i5-8600k @4.9Ghz, 2080ti , 32GB@2666Mhz, 512GB SSD
jmarso Posted July 18, 2019 Posted July 18, 2019 Besides it would seem like a major drawback consider that major airliner and jet cruise at transonic speed. Airliners don't cruise at true transonic speeds. Most are no faster than about .82 or so in cruise, and the fastest commercial planes (Citation X and one of the Gulfstreams) cruise at .92 or so. Once you get close to Mach, (faster than about .94 or so), the drag rise kills your fuel efficiency and range. The 727 was one of the fastest big airliners and it used to cruise at .89.
IronMike Posted July 18, 2019 Posted July 18, 2019 This oscillation is realistic and has been confirmed by our SMEs. You will encounter it above 450kts IAS. Heatblur Simulations Please feel free to contact me anytime, either via PM here, on the forums, or via email through the contact form on our homepage. http://www.heatblur.com/ https://www.facebook.com/heatblur/
ChockP51 Posted July 18, 2019 Author Posted July 18, 2019 This oscillation is realistic and has been confirmed by our SMEs. You will encounter it above 450kts IAS. That’s very interesting. Thanks for your reply. :thumbup:
ChockP51 Posted July 18, 2019 Author Posted July 18, 2019 I didn't find any speed limitation on autopilot usage in any of the RW docs or HB's manual. I do seem to recall though that at high supersonic speeds, the autopilot (or just SAS? can't remember) starts to create roll oscilations. Do you happened to know the source on this matter ? I love to read more about this.
VampireNZ Posted July 19, 2019 Posted July 19, 2019 I didn't find any speed limitation on autopilot usage in any of the RW docs or HB's manual. I do seem to recall though that at high supersonic speeds, the autopilot (or just SAS? can't remember) starts to create roll oscilations. NAVAIR 01-F14AAP-1, Chapter 4, Operating Limitations Vampire
sLYFa Posted July 19, 2019 Posted July 19, 2019 (edited) NAVAIR 01-F14AAP-1, Chapter 4, Operating Limitations Damn! The devil is in the details. Didn't see that, thanks for sharing. Chapter 4.1.6 actually for the non DFCS NATOPS Edited July 19, 2019 by sLYFa i5-8600k @4.9Ghz, 2080ti , 32GB@2666Mhz, 512GB SSD
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