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drift angle in horizontal flight


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Im usually aiming for 200 kmh to use my weapons as it seems to be a standart speed for rocket runs giving good accuracy.

 

However i have a problem with drift angle. I do the standart 0 degree bank, -2 to -4 degrees pitch and i use the rudder to center the ball. But with all these conditions met most of the time i have 3 to 8 degrees of drift angle to the left (seen via the right pilot's doppler device).

 

I cant seem to get rid of this left drift at 200 kmh. Is this just by helo design or what? This angle makes aiming difficult as you need to compensate laterally for it quite significantly.

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Your tail rotor is always pulling the helicopter to the left. To counteract that, you add some bank to the right. The more thrust your tail rotor is producing, the more right bank you'll need. For reference, zero thrust (flat pitch) for the tail rotor is just a little more than halfway from centered to full right. With the pedals centered, the tail rotor blades are at about 8.5 degrees of pitch angle.

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But then how does the helo acheive full right rudder?

 

Maybe it can't since the zero yaw point and the rotor blade angle "center" don't coincide, making the beast asymmetrical by nature?

The DCS Mi-8MTV2. The best aviational BBW experience you could ever dream of.

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When I say zero thrust I mean when the tail rotor blades are flat pitch and don't produce thrust one way or the other. Keep in mind that this does not mean the aircraft will fly straight, since torque effect is going to cause yaw. The tail rotor blades can go to 23 degrees of pitch one way (full left pedal) but only 6 degrees of pitch the other way (full right pedal). With the pedals centered, the tail rotor blades are at roughly 8.5 degrees of pitch, and that is pulling the aircraft to the left.

 

But anyway, more info on this effect can be found by googling "translating tendency".

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  • 1 year later...
Im usually aiming for 200 kmh to use my weapons as it seems to be a standart speed for rocket runs giving good accuracy.

 

However i have a problem with drift angle. I do the standart 0 degree bank, -2 to -4 degrees pitch and i use the rudder to center the ball. But with all these conditions met most of the time i have 3 to 8 degrees of drift angle to the left (seen via the right pilot's doppler device).

 

I cant seem to get rid of this left drift at 200 kmh. Is this just by helo design or what? This angle makes aiming difficult as you need to compensate laterally for it quite significantly.

 

 

 

 

My mates at the 229th have been testing this.

It appears that, in level flight, the DCS Mi8 drifts 8 degrees left at lower speeds, 3 degrees at higher speeds.

 

We're trying to acertain from RL pilots if this is modeled accurately.

 

 

In any event Prouty's article on Sideslip and Bank provides a nice overview of the phenomenon in general and piloting methods of correction.

http://www.rotorandwing.com/2018/01/26/ray-prouty-archives-sideslip-bank/

A Co, 229th AHB, 1st Cav Div

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JUST CHOPPERS

 

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