Rotor Pitch ?

[Justappl]

As a tin top PPL with little knowledge of helicoptors, could somebody please tell me .......

With the collective fully down to the floor, is the rotor pitch ....

a) Very fine
b) Zero degrees
c) Reverse pitch

I ask as I am confused about engine out procedures with regard to the collective setting.


Thanks.

[tail rotor drift]

The pitch is fine, since negative pitch would fly the blades towards the airframe. Some helis are able to give a downforce such as the Lynx.

[HeliAv8tor]

Well old chap, it depends on the helicopter and the type of blade. If the blade has wash out (a twist along the blade to attempt even the lift along the blade due to the increasing velocity the further you move out from the root) then you most definately have some fine pitch on the blade. As to the Lynx, well at MPOG (min pitch on the ground) there is NO pitch applied as the blade cord is assynetrical and there is no wash out. TRD get your QHI or your friendly Tiffy to explain! Cheers and never let your Nr exceed your your ability. Heli.

[SiClick]

As has already been said it all depends on the type of helicopter, but while the pitch will generally be quite low the angle of attack on the blades will not normally be negative.
In simple terms (or as simple as I can make it) Lift occurs at 90 degrees to the relative airflow, in autorotation - because of the high rate of descent - there is a flow of air up through the disc (called the rate of descent flow) which combines with the rotational airflow to make the relative airflow.
In places where the rate of descent flow is a high proportion of the rotational airflow (near the blade roots) the reaction to the relative airflow creates a force (autorotative force) that tries to speed up the blades. Futher out on the blades where the rotational airflow is higher the main affect is just lift, helping reduce the total ROD.
Any half decent P of F book should fill in the rest, but the main point as far as autorotation is concerned is that all helicopters can autorotate its just the amount of stored energy in the head and the ROD that will vary from type to type
Have fun, and safe flying

[MightyGem]

Justappl, regardless of how much pitch is on the blades at the minimum collective setting, in the event of total engine failure get the collective all the way down asap. Once your heart rate has stabilised you can then play with it if you need to glide (!!??) as far as you can.

[This message has been edited by MightyGem (edited 24 August 1999).]

[Ack2Main]

to heliav8or
I think you should check about the washout on the lynx