13th February 2014 at 23:28 - Edited 1st January 1970 at 01:00īTW, I don't think comparing aircraft turn rates at airshows is a valid method for comparing sustained turn rates.
With wings stalled, an aircraft has no means of controlling pitch motion this may even prevent reducing AOA to recover from stall/spin. At that point, it cannot point anywhere without TVC. What TVC actually allows is controllability Su-27 loses its yaw and roll authority at 28 deg AOA. In other words, strictly speaking of aerodynamics, Su-27s airframe design can reach 90++ deg AOA or 30++Gs without any TVC assist: Former is what you see as cobra maneuver, latter is the destructive effect that was the cause of the loss of the 2nd T-10 prototype. If unchecked by elevator intervention, this is a destructive effect. An increased AOA leads to increase in lift, which will try to incrase AOA even more. As a crude definition of negative stability, an increase in lift vector (pointing upwards) which is in front of the weight vector (pointing downwards) will create a momentum that will increase the AOA. Which leads to 30,19 deg/s instantenious turn rateĪlso to think TVC allows for higher AOA is also incorrect. Meaning 8,9Gs can be pulled at that speed. Using second graph, which says 24deg AOA can be achieved at M0.48 (V= 164.8m/s) Speaking of CL, Su-27 has Clmax = 1.85 at below 0.5
For example put a lower CL into formula and see how the turn rate goes down. This is a simple calculation I've made in another thread. At equal speed this exactly means lower instantenious turn rate. This will directly (and linear proportionally) decrease the pulled Gs. If it pulls harder, it will stall, and lift coefficient "CL" will drop below CLmax. Su-27's lift limit happens at 24 deg AOA. Highest instantenious turn rate is the turn rate happens at max available G, which happens at max available lift, or CLmax. Thrust vectoring does not allow higher instantenious turn rates. It isn't a 100% accurate figure either, since some aircraft with poor wing loading actually end up being more maneuverable than other aircraft with very good wing loading. Wing loading alone is also misleading, since a lot of aircraft create additional lift via the fuselage. What creates added drag is the higher instantaneous turn rate, which TV allows for. Thrust vectoring nozzles by themselves do not create drag.
0 kommentar(er)
