trim/rudder/aileron tab-life or death?

[PPRuNeUser0179]

just a general question...

are the trim,rudder and aileron tabs COMPLETELY neccesary for flight?as in,if you do not use them,is it a matter between life and death in normal everyday circumstances?
im in rotorwing so dont reallllyyyy have a clue.

thanks.

[His dudeness]

For sure not in my airplane....if one would fly at speeds not much higher than V2 it would be almost no difference. (if trim is set to proper position for T/O)

Aileron trim is hardly ever used in 'my' airplane and rudder trim also (OTOH if you fly a Challenger 300 you will use that a lot) and elevator trim is used constantly, forces on the stick can become really, really heavy when that goes in to an extreme position not compatible with the speed flown....

AFAIK certification requires flight with Trims simulated stuck in extreme positions. One would end up with higher approach speeds and hence longer airfield requirements (and other possible restriction, e.g. such as high speed limit for unusable Mach trim)

My airplane has only one means (elec motor) for aileron and rudder trim, whereas there are a primary and secondary (slower) elevator trim.

[PPRuNeUser0179]

hey HD..
i thought so as much for the use of the trim elevator tab,but not really the aileron and rudder trim...i saw in SA flyer magazine in South africa that an aircraft crashed (either on T/O or landing)due to "INCORRECT RUDDER TRIM".but i understand the elevator trim..i will post a better reply but am EXTREMELY BUSY at the moment.
thanks again HD

[goldeneaglepilot]

Is your age a typo? Or are you busy doing your homework? :):)

Rudder trim can be a big help in a twin with the engine out. Some types also get help by trimming the ailerons

[PPRuNeUser0179]

hey GE

no.busy with someone trying to skype me :)

so like i mentioned above,there not really a need for aileron and rudder trim?

[mad_jock]

When you have your first engine failure on a twin you will understand why they have them.

I think the max allowable force to be applied to the rudder is 35lbs. You can't hold that for an approach never mind the go around.

Same with the roll trim the forces are such that you can hold it for a short while but stamina becomes a factor quite quickly.

With singles the more powerfull and the greater the range of speeds across whch they operate means more trimming is required across the range of flight speeds and power settings.

[Fossy]

from a technical stand point, I would say no they aren't. That's also why they are called secondary flight controls.

Source wikipedia:

Secondary controls

In addition to the primary flight controls for roll, pitch, and yaw, there are often secondary controls available to give the pilot finer control over flight or to ease the workload. The most commonly available control is a wheel or other device to control elevator trim, so that the pilot does not have to maintain constant backward or forward pressure to hold a specific pitch attitude[4] (other types of trim, for rudder and ailerons, are common on larger aircraft but may also appear on smaller ones). Many aircraft have wing flaps, controlled by a switch or a mechanical lever or in some cases are fully automatic by computer control, which alter the shape of the wing for improved control at the slower speeds used for takeoff and landing. Other secondary flight control systems may be available, including slats, spoilers, air brakes and variable-sweep wings.

[Tinstaafl]

If certified under Part 23 then the rudder pedal force may be up to 150lb. After trimming there may be a residual up to 20 lbs. Even control column forces can be fairly hefty. Certainly enough that trim is necessary for continued controlled & safe flight.

§ 23.143 General.
top

(a) The airplane must be safely controllable and maneuverable during all flight phases including—

(1) Takeoff;

(2) Climb;

(3) Level flight;

(4) Descent;

(5) Go-around; and

(6) Landing (power on and power off) with the wing flaps extended and retracted.

(b) It must be possible to make a smooth transition from one flight condition to another (including turns and slips) without danger of exceeding the limit load factor, under any probable operating condition (including, for multiengine airplanes, those conditions normally encountered in the sudden failure of any engine).

(c) If marginal conditions exist with regard to required pilot strength, the control forces necessary must be determined by quantitative tests. In no case may the control forces under the conditions specified in paragraphs (a) and (b) of this section exceed those prescribed in the following table:Values in pounds force applied to the relevant control
Pitch Roll Yaw
(a) For temporary application:
Stick 60 30 na
Wheel (Two hands on rim) 75 50 na
Wheel (One hand on rim) 50 25 na
Rudder Pedal 150
(b) For prolonged application 10 5 20