Skyediamonds
Staff Sergeant
- 1,201
- May 26, 2018
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Why do you single out the Spitfire? The challenge is delivering fighter performance with good control, so its quite possible something like a Harvard trainer is better than a fighter. The best fighters are on the edge of stability, it means they change direction more quickly.
Like any high performance car or motorcycle, great to drive or ride but you cant spend any time gawping at the countryside.The "perfect" fighter would have dead neutral stability on all 3 axes ... it would also not be fun to fly it on instruments, but it would be very responsive to pilot inputs.
In 1940 production over road development, metal elevators weren't the issue with the Spitfire, it was the profile. Like all fighters it wasn't until they were pushed to their limits in an actual war that problems presented themselves, the fabric elevators ballooned at high dive speeds and the initial metal elevators gave no improvement, it wasn't until the profile was changed that there was a marked improvement in their performance.Why do you single out the Spitfire? The challenge is delivering fighter performance with good control, so its quite possible something like a Harvard trainer is better than a fighter. The best fighters are on the edge of stability, it means they change direction more quickly.
Good point, what people forget is the Me109 had the very same issue, Spitfires and 109's tangled as high as 30,000 feet and above during the BoB, ran the engines at over boast, dived at speeds well above peacetime velocities and turned as hard as physically possible, it's no surprise the pilots of both experienced handling issues that lesser aircraft never suffered from.Also note that a slow fighter has an easier time of this, since the force acting on the control surface (or force needed to move the control surface) goes up with the square of the speed.
This not the same as trim. ( I don't think, I am not a pilot) Trim is adjusting the force needed as the speed changes so that plane responds the same way both ways, as in rudder makes the plane yaw the same amount both ways with the same amount of rudder deflection. This will change at different speeds. Or the elevator needs trim to make the elevator respond correctly at different speeds. Since the horizontal stabilizer exerts negative lift in proportion to the square of the speed the trim is there to try to keep the force needed on the elevator to within the desired range. If the fabric on the elevators balloons it can limit the ability of the of the elevators to affect the air flow and thus the control of the plane.
But it is all a balancing act. The planes that are "pilots" planes have the least change in the control inputs for a given result over the common speed range.
Shortround6,
Per an aviation website: Aircraft trim holds control surfaces (rudder, elevator, or ailerons) in a specific position, requiring less manual input from the pilot to maintain a desired flight attitude. Trim either moves entire control surfaces (like on a stabilator) or is installed as a separate trim tab (like on an elevator).
Trim is used to relieve pressure on the flight controls. For takeoff in the F15 we would put the trim in the "green" (little pushbutton that would reset the flight controls in pitch to the takeoff position). The takeoff position allowed the aircraft to have a slight pitch up at normal weights at takeoff speed. As the plane accelerates and without trimming the stick you would have to push forward at greater amounts as speed increased just to maintain level flight or a shallow climb. At pilot training we were hammered initially with "trim trim trim" so as to make it easier to fly the plane (a trimmed up plane requires less brain cells to fly). A aircraft will be trimmed for a speed. At 250kts and level, unacclerated flight, and trimmed up, the plane will pretty much hold altitude. Push the power up and it will climb pretty much at 250kts. Pull the power and it will descend at 250. You trim for airspeed and power for altitude.
As for the rudder, it's just like the elevator on cable or pushrod flight controls in that the faster you go, the more force you will need to put on it to get the plane to move. It will move more for a given amount the faster you go (greater force acting up the surface, less movement gives more reaction).
Now to totally distort what I wrote here is what the Thunderbirds and Blue Angels do. When flying a trimmed up plane there is a little dead spot (hydraulic flight controls) as in you can move the stick just a tiny bit and nothing much happens. When watching a two ship of jets in formation flying into the pattern you would think they were glued together. However, if you were the wingman you would be bobbing around just a little and making constant power and flight control inputs in order to stay in position. That little bobbing is almost eliminated in our two demonstration teams by flying with full nose down trim while doing the show. Yep, crazy sounding shit but they do it. The F16 will slowly pull the trim back to 1g, while the F18 does it rather quickly. End result, the T-Birds are constantly trimming nose down (about 45lbs of force pull back required to hold it level) and the Blues use a bungee cord attached to the center pedestal that is put on the stick to pull it forward. In full disclosure I haven't seen the Blues set up, but have spoke with enough T-Bird guys who relayed that to take it as truth. The F16 stick literally only moves about 1/8 inch in any direction. I have tried doing this and absolutely hated it in pitch, but in roll I would put a couple of clicks on aileron into my flight lead when flying close as it helps "hold" you in position.
A car analogy would be driving at 20 mph your car pulls to the left. At 30 it tracks straight, and at 40 it pulls to the right. It's "trimmed" for 30 mph. Trim allows you to reset the speed at which it tracks straight.
If someone can explain it better feel free to chime in as I never instructed at the primary level.
Cheers,
Biff
Let me help you with that.never instructed at the primary level.
Why is the blue whale turning left?
You'll never know the crazy fun you missed!I never instructed at the primary level.
Cheers,
Biff
Haven't even gotten off the ground yet???