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Rotor Droop


CT Modeller

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Hi Sam,

The topic is over a month old, I know, but since I got here using the "Search"-function, chances are that someone else looking for Wessex-rotorblades will too, in the future.

On the position of the blades on the drag-hinges: as you describe it is of course when displaying the blades as an X on the helicopter. But for the blades to all hang forward on the drag hinges would require the rotorhead as a whole to be tilted forward. As far as I have understood, the fully articulated rotorhead on the Wessex doesn't do that? The "forward tilted" rotordisc for forward movement is created by having less AoA on the front blade and more on the aft blade. Because of the flapping hinges the aft blade will ride higher than the forward blade, in effect creating a forward tilted rotordisc. Therefore the blades at rest should be in the neutral position on their drag hinges since the dampers would push them to that position when parked?

The blades at rest in their flapping-hinges is another case, although the effect on the Wessex is much less obvious than on the Chinook for example. What is very obvious is the top two blades of the tail rotor when parked in an X-position. They certainly hang forward on their flapping hinges!

I don't really know very much about helicopters, so if I'm wrong please don't hesitate to correct me. If it does actually make any sense, please let me know too! ;)

I based my train-of-thought (or brain-fart) on the following:

http://www.aviastar....eory/rotor.html

Cheers,

Erik.

Having looked at many a helicopter from above over the past thirty five years, I hopefully know a little about this subject. A Puma's main rotor gearbox and head is tilted forward by 5 deg and whilst I can not remember what the Wessex rotor head( last worked on them in 1980) it did have some forward moment 2 -4 deg. Futher to this I have seen many a Wessex from above, after all we had 28 of them and I can remember on one night shift having to grease 14 of these and each one had 52 grease nipples, 52 x 14= 728.

Tail rotor's do not have such a device as a drag dampers ( lag damper on Chinook) the blades seem to flop forward at the top or try to drop. Please don't go in to Chinooks, as these helicopters are in a world of tech of there own. The blades are only fixed at one point to the head and therefore until one attaches the lag damper they are very unstable to control often with about two/ three men holding the end of the blade until the lag damper is attached.

SF

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Having looked at many a helicopter from above over the past thirty five years, I hopefully know a little about this subject. A Puma's main rotor gearbox and head is tilted forward by 5 deg and whilst I can not remember what the Wessex rotor head( last worked on them in 1980) it did have some forward moment 2 -4 deg. Futher to this I have seen many a Wessex from above, after all we had 28 of them and I can remember on one night shift having to grease 14 of these and each one had 52 grease nipples, 52 x 14= 728.

Tail rotor's do not have such a device as a drag dampers ( lag damper on Chinook) the blades seem to flop forward at the top or try to drop. Please don't go in to Chinooks, as these helicopters are in a world of tech of there own. The blades are only fixed at one point to the head and therefore until one attaches the lag damper they are very unstable to control often with about two/ three men holding the end of the blade until the lag damper is attached.

SF

Hi Simon,

Thanks for your reply! Please don't take my little reasoning exercise as being meant to belittle your experience! I didn't even know you work(ed) on them. It struck me as odd to have the blades hang forward on their drag dampers if the rotorhead was mounted fully horizontal. Well, that "fully horizontal" was my flawed assumption! ;) And you know what they say about assumption.....*

Since Smudge and you have now confirmed that the gearbox + rotorhead was mounted with a forward tilt, I'll build my Wessex with the blades forward too!

And Perdu will probably be happy too that his builds are accurate! ;)

Cheers,

Erik.

* "Assumption is the mother of all F*ck-ups!" :whistle:

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