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Guest IanK

elevators effectivity

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Greetings,I have some questions about the elevators effectivity part of the .air file section 341. I have the AMM with the updated .ini file. What I am trying to achieve is with an ELEVATOR_UP_LIMIT of 1.5 and an ELEVATOR_DOWN_LIMIT of 9.5 I am trying the get the plane to get about +6 G's and -4 G's with a rate of speed of around 500 kts. I read the notes above the graph, but I don't understand what the graph is telling me. I played around with some numbers and made different things happen, but I don't know what I am doing. The aircraft is Rick Sasala's A-6 Intruder, and I am trying to get it to fly correctly with all the perameters out of the Navy flight manual. Any suggestions would be appreciated.Many Thanx, Christopher Raison.

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>Greetings,>>I have some questions about the elevators effectivity part of>the .air file section 341. I have the AMM with the updated>.ini file. What I am trying to achieve is with an>ELEVATOR_UP_LIMIT of 1.5 and an ELEVATOR_DOWN_LIMIT of 9.5 I>am trying the get the plane to get about +6 G's and -4 G's>with a rate of speed of around 500 kts. I read the notes above>the graph, but I don't understand what the graph is telling>me. I played around with some numbers and made different>things happen, but I don't know what I am doing. The aircraft>is Rick Sasala's A-6 Intruder, and I am trying to get it to>fly correctly with all the perameters out of the Navy flight>manual. Any suggestions would be appreciated.>>Many Thanx, Christopher Raison. It's probably better to leave TBL 341 flat in your case. However, TBL 517, 'Elevator deflection vs q' can be used to reduce elevator deflection as speed increases. 'q' is dynamic pressure, and runs about 40 lb/ft^2 at 120 kts IAS. I see I set TBL 341 for a high speed fighter so y = 1.00 at x (q) = 200 lb/ft^2. Dropping to 0.6 at q = 500. That means the elevator deflects to the full limits set in aircraft.cfg up to q = 200. Which is rougly 210 kts IAS. But, drops to 60% at q = 600, which would be sqrt (600/200) * 210 kts. About 360 kts IAS. That way, one can limit how many G's can be pulled at higher speeds. Assymetrical elevator deflectons are common, but create problems. You might reduce the assymetry to +3 deg, - 6 deg in aircraft.cfg. At least the annimation will still show more down than up deflection. However, you need to have the AC in trim with zero elevator from the JS. REC 1101, "Pitch Moment Coeff at AoA =0 (trim offset)" can be edited to give an elevator trim near 0 degrees in normal flight. Actually, 1101, "Pitch Moment - Horizontal Stabilizer" has a similar effect. 1101, "Pitch Moment - Elevator" sets the amount of pitching moment elevator deflection creates. I set it to get about the right +/- G load at nominal speeds. Then, set TBL 517 to reduce the G load at high speeds. Which makes the AC less sensitive, and probably more realistic. Note hydraulic control actuators might 'blow down' at higher speeds and not move a control as far as it moves at low speeds in real AC. This is especially true for the rudder. Which I have been dropping rapidly after q ~ 70 in my more recent jet AIR files. Ron

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Hello Christopher,the ELEVATOR_UP_LIMIT of 1.5 and an ELEVATOR_DOWN_LIMIT of 9.5in the .cfg file are in degrees and are typically +- 45 deg say.Otherwise the elevator authority is a function of the lever arm length, the deflection of the elevator and of the air flow and air speed.Ian

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