........and in even more ancient times a oiled (used, dirty black oil) brush was slowly pushed up and then after shut down the lowest blade was ascertained and adjusted. Once the brush hit all of them together there was then a short airtest to see by how much the autorotative RPM had altered.

The Sycamore had bullet shaped mass balances on the end of the blades. A flag wouldn't have lasted a single revolution.

Lots of things didn't last long on the Sycamore :ok:

Didn't the 214ST have one adjustable tab (from a wheel in the cockpit) to adjust the tracking in flight?

"nobody explained to me", are you kidding?, what kind of helicopter education did you get??
why did you never ask??
so that's what the JAR system turns out. pathetic.

AC,

It was actually one of the pitch horns!

It adjusted the connection point of the P/L to the pitch horn on an eccentric on one blade.

http://oh1ninja.la.coocan.jp/details...4_034_trim.jpg

The opposite blade had a counterweight in this position.

http://oh1ninja.la.coocan.jp/details...ell214_098.jpg

Soave pilot

They ARE supposed to have the same tip-path plane on conventional heads. For the Bell 412, where the pairs of blades are clamped one on top of the other, there will be that same split at the tips, but each pair of blades will have the same path.

But do not always if tracked for minimum vertical vibration as opposed to same track.

Evident on many different models.

Tracking et al.......
 

Yes, indeed, that's the theory, anyway - all in the same tip-path plane. That's what the aerodynamacists prescribe, but real life, on occasion, will define slightly differently :uhoh:

Two standards to bear in mind here, composite (modern) blade construction and traditional (old) design. The former are less 'individual' and, by and large, one can aim for constant tip path plane (TPP), achieve it, and probably the 1R vertical will be down to an acceptable level. :ooh: (OB is absolutely correct for the 412, you'd aim for two sets of TPP. BUT you would be using the RADS and if it recommended an adjustment that transgressed that generalisation, it might be a good idea to follow it's predictions/adjustments.:ok:). 'Modern' blades are mostly 'on condition' without a finite (Timex) retirement life. :oh:

The earlier standard is not quite so simple. Comprising metal construction with a spar, filler and Al skin, at design level the ethos is to have individually replaceable blades throughout the prescribed TIMEX life, i.e. the ageing process is predicted not to alter a blade's individual characteristics within that life, that cannot be compensated for with the adjustment of PCL and T'tab provided. :hmm:

BUT........ age can do all sorts of different things to the metal construction, particularly the spar. Some age-harden with the extreme flexing a blade must accommodate in normal service; others become more flexible over their lif-span, at the same time altering the amount of washout originally built-in to the blade at manufacture. :E

Now you begin to see the complexity of the task of getting all these blades to 'live' together. At the risk of being terribly policitically incorrect, I have described this aspect as an analogy to women. :mad: Difficult to get all of them to see eye to eye, and age adds a frisson of unpredictability to the equation. AND the more of them you have the more complex the problem can rapidly become, (Are you all still with me, or with the Woolwich?) :ugh:

A VERY senior engineer told me, before he disappeared to the great bar in the sky (where I'll bet he's racking up my bar bill like there's no tomorrow) that if the life discrepancy between the blades is more than 400 hrs, then you will have to accept a compromise on vibration levels somewhere between Hover and Vne. :( Fact of life as far as he was concerned, and as a maxim to guide you it has done me proud over the years. :ok:

So that's what I bring to the table. I'm not an expert, but been doing it for a few years (ask TRC!). Essentially we are looking for a vibration-free ride (utopia), and the actual TPP pf the blades is a secondary consideration. :cool:Can be a bitch of a rotor to work sometimes; think of your engineer with respect and affection, he doesn't want to be playing with it all day long, any more than you do. A beer would be a MUCH more worthwhile activity to pursue. :ok: :ok: :ok::D

Fly safe - VFR

Absolutely correct vfr440, the aim might be to track so that all blades fly in the same plane but in reality you track for vertical bounce free flight.
By using pitch rods for ground track and trim tabs for forward flight you can usually get it close but with a miss matched set of blades(altered blade characteristics) some times it's impossible and the only recoures was to try another blade to see if you can acheive a better match.
Oh yes and as fareastdriver mentioned always recheck auto rpm after track adjustments

Two or three decades more like. (Hello Chip).

I had the pleasure of tracking a rental blade with a temporary partner of considerably different age/hours/temperament.
Ended up with max 'up' tab on one and max 'down' on the other - just got it acceptable up to about 110kts. Any faster would have meant a trip to the back doctor and the dentist. Lucky it was only while the original was being repaired - that was a bundle of fun when we got it back too.

Trubble wiv blades
 

Hello Jack-not-bloody-Tom :D
Yes, I remember that one, and then Bell came out with TWO trim tabs/blade (and a convoluted chart to programme the Vibrex as well?)

And this is hard work for an expatriate Cornishman who's only just mastered joined-up writing. Chip Bath working overtime......:ugh: (Sorry, that's an in-joke from AMH, somewhat akin to 'Capt Average', you recall? ........:))

Keep the revs up - VFR