Tail blowouts on fast inverted backwards left hurricanes

I am trying to figure out why I keep experiencing scary tail blowouts when performing fast inverted backwards "left rudder command" hurricanes. This happens with several helicopters.

I would have thought that I would encounter the limit on tail authority when performing "right rudder" maneuvers, as "right rudder" is constantly "fighting" the main rotor torque. Again, I have no issues whatsoever with right rudder command fast inverted backward hurricanes. Fast inverted backwards left rudder command hurricanes is another story. I am experiencing tail blowouts when I conduct these fast inverted backwards left rudder command hurricanes. I can hear the tail sounding angry during the maneuver, and then the tail lets go and ends in an unexpected orientation. Flying up high is no problem, but I don't trust doing these fast inverted backwards hurricanes close to the ground when I know the tail can blow out.

I've already adjusted the main tail gain and the tail I-gain as high as can be without feedback oscillations. I am also using optimal tail servo arms to yield around 100L/100R tail slider travels from end to end of the tail shaft without binding.

I am wondering if the tail blades may be stalling from too steep pitch angles since I am using the full travel (without binding) of the tail slider on the tail shaft? I am wondering if I should dial back the left tail travel 5 or 10 points?

It is a stall, definitely.

To fix it: Balance the tail load with the other commands - collective and cyclic management ;-) -or more tail speed or loger tail blades ...

One note - having too much throw is also not the best - the tail will be able to flip over being on the edge here. lowering a few points is more controllable by the pilot as he mentions it but it won't flip over.

regards (EN) / Gruss (DE)

Rainer Vetter

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Thank you for the response. What do you mean by the tail blade "flipping over" at the extremes of slider throw?

If the tail throw is massively too much and the blade angle is short before a stall - but has unused throw - the control loop gives more throw (as tail doesnd keep in place) - and then the stall effect happens, atil flips into flight direction and is useless unless the throw or load is reduced.

If you have just the right amount of max throw to keep it in the limits (a brief moment before it stalls) you will notice that the tail turns slowly but does not flip in your situation.

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.