LJQCN101 Posted September 27, 2017 Posted September 27, 2017 Just an interesting find. I did a simple test to compare the short period pitch characteristics and FCS response of both aircraft. In Su27, pitch response is much slower when reacting to a full aft-stick command. It also takes longer for Su27 to reach a certain pitch rate compared to Su33. When controls are released, Su33 recovers faster to zero pitch rate. Su27: Su33: You can notice the FCS of Su33 drives the horizontal stabilizer much quicker and to a larger extent when responding to the same pitch command. EFM / FCS developer, Deka Ironwork Simulations.
LowLee Posted September 27, 2017 Posted September 27, 2017 There are some differences in trimming too. The su 27 needs more pitch trim ---------------- inviato con un telefono a gettoni Fletto i muscoli...e sono nel vuoto [sIGPIC][/sIGPIC]
Slutcher Posted September 27, 2017 Posted September 27, 2017 This can be partially due to the lack of an adaptive limiter in current Su-33 PFM as it drastically slowered the control response when it was introduced for the Su-27. http://www.51bisons.com
Esac_mirmidon Posted September 27, 2017 Posted September 27, 2017 Well, the Su-33 is a full FBW three axis channel, the Su-27 only in pitch axis. Also canards could have some weight in the response equation. " You must think in russian.." [sIGPIC][/sIGPIC] Windows 7 Home Premium-Intel 2500K OC 4.6-SSD Samsung EVO 860- MSI GTX 1080 - 16G RAM - 1920x1080 27´ Hotas Rhino X-55-MFG Crosswind Rudder Pedals -Track IR 4
jackmckay Posted October 9, 2017 Posted October 9, 2017 Allays comparing to Eagle as reference but..If someone says that Eagle is more pitch agile because of stronger hydraulics that doesn't stand at all because Flanker doesn't require that strong hydraulic to pitch up even it has stronger engines that can deliver more power to hydraulic pumps. Roll is actually more hydraulic power demanding because of wider weight distribution causing high inertial roll resistance. Flanker has closer CG to AC point so when these two invert it performs Cobra, nose pitch up, tail goes under forward.. and for that maneuver flanker uses less hydraulic power than more stable designs as Eagle itself so that means that pitch deflection rate depends primary on airframe design and secondary to hydraulic power available. In general, booth Flanker and 33 have to perform faster pitch deflections and that is very crucial in combat agility and performance of defensive maneuvers and there is also a question of how ED calculates neutral AoA cos it seems that some modules have higher AoA in level flight than they should. Flanker is entangled for sure. Generally, I don't care much about that, cos ED gives a damn, but take a look at this standpoint. Having flanker "entangled" means that all those brilliant Eagle/M2K/F14/F18..etc pilots won't be given a chance to prove their real skill and proficiency while playing against "entangled" opponent and that means no respect for pilots fighting Flanker in MP.
Weta43 Posted October 9, 2017 Posted October 9, 2017 If you take a rod, and try to turn it by just pushing it sideways at one end with two identical actuators, you'll produce a torque that turns the stick around its centre of gravity, but also a net force that moves the stick's centre of gravity in the direction of the push. That's the Su-27 with only a horizontal stabiliser. if you split the same amount of force between two actuators one at each end of the stick, with one pushing down as in the original case, and the other pushing up at the opposite end, you'll get more torque for the same applied force (so a faster rate of turn), and no net movement of the COG. That's the Su-33. Cheers.
Wizard_03 Posted October 10, 2017 Posted October 10, 2017 I didn’t know the su-33s canards were powered, I thought they functioned with AOA changes and air flow, similar to leading edge flaps. IE the don’t apply force like the stabs they just kinda float there DCS F/A-18C :sorcerer:
Weta43 Posted October 10, 2017 Posted October 10, 2017 They look to be aligned to provide lift (not aligned with the airflow) in this snip from the demo video Cheers.
Wizard_03 Posted October 10, 2017 Posted October 10, 2017 (edited) They look to be aligned to provide lift (not aligned with the airflow) in this snip from the demo video Yeah your right, my mistake. Image below shows them opposite direction relative to the stabs. If that's case, the Su-33 would definitely have more pitch authority in both rate and speed. Since as you can see force is applied on both ends of the aircraft CG in opposite directions. Same thing for applied positive pitch. Edited October 10, 2017 by Wizard_03 DCS F/A-18C :sorcerer:
LJQCN101 Posted October 10, 2017 Author Posted October 10, 2017 (edited) If you take a rod, and try to turn it by just pushing it sideways at one end with two identical actuators, you'll produce a torque that turns the stick around its centre of gravity, but also a net force that moves the stick's centre of gravity in the direction of the push. That's the Su-27 with only a horizontal stabiliser. if you split the same amount of force between two actuators one at each end of the stick, with one pushing down as in the original case, and the other pushing up at the opposite end, you'll get more torque for the same applied force (so a faster rate of turn), and no net movement of the COG. That's the Su-33. Flight control plays its role too. It seems that Su-33 uses a much more optimized pitch rate/loop gain schedule than Su-27 which enables it to deflect its elevator faster for the same pitch command. Therefore, Su-33 applied a greater force at one end of the stick. Edited October 10, 2017 by LJQCN101 EFM / FCS developer, Deka Ironwork Simulations.
Recommended Posts