Bell UH-1

[bell_pilot]

The mast is tilted 5 degrees forward.
Maximum flapping angle is 15.55 degrees.
If you did so, you are correct as i understand your intention.

[bomber]

oh yes !

It feels good when one of your guesses hits target

[bell_pilot]

oh yes !

It feels good when one of your guesses hits target

[bell_pilot]

Maximum flapping angle is 15.55 degrees.

Correction:
Maximum flapping angle is 12.391 degrees.
Sorry....

[bomber]

no problems

[bell_pilot]

Thesis:

Maximum flapping angle is 12.391 degrees.

This value is the angle if the blade is stiff.
In forward speed, due to the stiffness of the blade, some deflection may occur. Near VNE this deflection angle is at maximum. (No certain info for our models.)
https://apps.dtic.mil/dtic/tr/fulltext/u2/a034459.pdf
I found and browsed over this report. At 140 kts, the experimented blades deflected around 2.3 degrees.
I dont know if yasim calculate the deflection. I dont think so since i havent seen any input about stiffness data in YASim.

Thus, 15 degree is the correct answer.

What do you think?

[bomber]

ok I'll use 15.55 degs...one thing I have noticed is that I now need to add damping to this as a result of rotation velocity, otherwise it enters into oscillation

[bomber]

Ok another question..... It's all to do with the tail rotor control.

The main rotor spins up to 325rpm and the tail to 5x this at 1620rpm

Is there some kind of fancy control that adjusts the tail rotor blade angle as the main rotor blade angle is adjusted by the collective ?
ie are they tied in together so as when the main rotor produces more torque the tail rotor produces more counter torque.

So the thing that then occurs is a kind of lag such that the pilot has to adjust slightly the tail rotor blade angle with his peddles whenever there's a change in main rotor collective. But when the collective is held steady and there's no side wind the peddles are at neutral.

????

Simon

[bell_pilot]

Is there some kind of fancy control that adjusts the tail rotor blade angle as the main rotor blade angle is adjusted by the collective ?
ie are they tied in together so as when the main rotor produces more torque the tail rotor produces more counter torque.

They are not tied in together. Tail rotor pitch angle is controlled by pedals, to adjust necessary anti-torque. Rpm remains same in normal flight conditions.

So the thing that then occurs is a kind of lag such that the pilot has to adjust slightly the tail rotor blade angle with his peddles whenever there's a change in main rotor collective.
Simon

Exactly. Left pedal for collective up, right pedal for collective down. (for CCW rotor)

But when the collective is held steady and there's no side wind the peddles are at neutral.
Simon

Not always. Below trans-lift speeds (below~24kts) left pedal is ahead relatively. Cos' more torque is applied. Why? Rotor inflow degrades its effectiveness by vortexes created on the tip of the rotor.
Above trans-lift speeds(above ~ 24kts) right pedal is ahead relatively. Main rotor effectiveness is enough so less power is needed(less torque applied). So pilots slowy change pedal position from left to the right while take off and passing ~24kts.

For UH-1H, when take off and passing 24kts:
Apply pedal left to right
Apply cyclic fwd and left(left pedal for higher tail rotor moment due to clean-air working state.)

Why fwd cyclic applied while passing trans-lift speed?
Higher effective main rotor blades produce more lift, vortex are gone away now, begins to flapps up. Advancing blade ,on 3 o'clock position, starts to flap up and reaches max flap angle on 12 o'clock position.

[bomber]

Do you fly with peddles, or a twisty ?