Track and balance blades?
Wingman150
>developed by a British company...it uses an optical tracking camera along
>with
>accelerometers and a sensor that detects when the target blade comes around.
>Used to be, they used what was called a Vibrex kit, which was like a timing
>light for a car. The Vibrex they used for the main rotor and a stick with
>chalk
>for the tail rotor.
>
>The RADS uses a computer program to take all the measurements and compute the
>required adjustments based on the aircraft being measured. This compared to
>using charts with the vibrex.
>
>Only trouble with the RADS is when the Maintenance Pilot or Crew Chief fails
>to
>realize that it is just a tool and that the adjustments it gives are just
>recommendations. Whereas the vibrex, you used the chart and your head to tell
>you what adjustments to make.
>
>I'm unaware as to how the civilian side does it. I assume they have a
>computerized method. I also assume they've had it longer than the Army has
>had
>the RADS.
>
>
>Born2fly
>Living the Dream
Yeah, thats more like it...I just didn't know how to explain it...Its like
doing a timing job on a car but much harder. :o)
Jordan
BORN2FLIE
Wingman150
>does anyone have references as to how this is done..and how typically best
>accomplished... i mean how does one "track" anything as a rotor blade thats
>flopping all over the place anyway?
>
Hey Doug,
You get this little machine...Can buy it from Rotorway I think. You fire up the
machine while you have this gadgit hooked to the front of your helo, and rigged
to your cyclic. You get it into a hover, then you push the button you have
rigged to your cyclic a few times. It gives you some readings and by that you
set it down, and start balancing. Hard to explain, and I really don't know a
whole lot about it, but I watched Fred Stewart and Badwater do it in Vegas with
the Mini-500.
Jordan
CountVoo
KENNETH BOOTHE
Before all this hi tech equipment a tracking flag was used
on the main rotar and as already stated a stick and chalk
on the tail rotor. Ken
Wingman150 <wingm...@aol.com> wrote in article
<19990208112851...@ng123.aol.com>...
Stan Gosnell
>I read of ... "tracking and Balancing" the rotor blades.
>does anyone have references as to how this is done..and how typically best
>accomplished... i mean how does one "track" anything as a rotor blade thats
>flopping all over the place anyway?
First, you find out where the blades are flopping. The object is to
get them all to flop in approximately the same place. After you find
out, usually using computerized equipment, you make adjustments to the
blade trim tabs, blade weights, and/or blade control rods. Fly,
adjust, fly, adjust, repeat until the vibrations are minimal. This
can take hours or days or weeks, depending on the aircraft & the
mechanic & the tools.
BORN2FLIE
smoother if you balance the rotor system first and then track the blades.
>First, you find out where the blades are flopping. The object is to
>get them all to flop in approximately the same place.
Actually, the idea is to get them to fly in the same path, called the plane of
rotation or "tip-path plane". What this does is help to eliminate vertical
vibrations and you get more predictable aerodynamics from the rotor system
because each blade is "copying" the one before it.
Born2fly
Living the Dream
vic
>
> I talked about the RADS kit earlier. I wanted to mention that it usually goes
> smoother if you balance the rotor system first and then track the blades.
>
> >First, you find out where the blades are flopping. The object is to
> >get them all to flop in approximately the same place.
>
> Actually, the idea is to get them to fly in the same path, called the plane of
> rotation or "tip-path plane". What this does is help to eliminate vertical
> vibrations and you get more predictable aerodynamics from the rotor system
> because each blade is "copying" the one before it.
>
> Born2fly
> Living the Dream
>
the technical answers such as yours. Considering the level of
rotorcraft knowledge possessed by the type of person who would asked
such a question, Stan's answer would probably make the most sense. -vic
--
Maybe two engines, but one main rotor is enough.
.
No spam - just com - not net - - and att has no l
HaroldA102
it has a srtobe light in it
Stan Gosnell
>I talked about the RADS kit earlier. I wanted to mention that it usually goes
>smoother if you balance the rotor system first and then track the blades.
>
>>First, you find out where the blades are flopping. The object is to
>>get them all to flop in approximately the same place.
>
>Actually, the idea is to get them to fly in the same path, called the plane of
>rotation or "tip-path plane". What this does is help to eliminate vertical
>vibrations and you get more predictable aerodynamics from the rotor system
>because each blade is "copying" the one before it.
>
>Born2fly
>Living the Dream
Actually, you will never get them to fly in the same path. It is
impossible to exactly duplicate blades, they will have slightly
different stiffness, weight, etc. The blades on a Bell 412 aren't
even in the same plane to start with. I have never seen a ship with
all the blades all flying in exactly the same path. Very often, you
can see that the blades are out of plane, but there is no significant
vibration. The object is to minimize vibration.
Stan Gosnell
>I read of ... "tracking and Balancing" the rotor blades.
>does anyone have references as to how this is done..and how typically best
>accomplished... i mean how does one "track" anything as a rotor blade thats
>flopping all over the place anyway?
"Flopping all over the place" is a true statement. Anyone else seen
the film Bell made by placing a camera on the mast of a UH1, pointing
out to the end of the blade? UH1 blades are about as stiff as they
come, & in flight that thing looked like well-cooked spaghetti. Shown
that when just starting flight school, I was impressed.
Bill Sykes
On Fri, 12 Feb 1999 15:54:11 GMT, st...@hal-pc.org (Stan Gosnell)
wrote:
>"Flopping all over the place" is a true statement. Anyone else seen
>the film Bell made by placing a camera on the mast of a UH1, pointing
>out to the end of the blade? UH1 blades are about as stiff as they
>come, & in flight that thing looked like well-cooked spaghetti. Shown
>that when just starting flight school, I was impressed.
>
As was I. It makes one wonder how they stay together at all. Not
exactly the film you want to show to someone who has never been flying
in a helicopter before. (Though it would be fun to see a newbie's
reaction just before you loaded him up to take him offshore ; - ) )
Bill Sykes
"Aviation in itself is not inherently dangerous. But to an even
greater degree than the sea, it is terribly unforgiving of any
carelessness, incapacity, or neglect" Author unknown.
BORN2FLIE
>the technical answers such as yours. Considering the level of
>rotorcraft knowledge possessed by the type of person who would asked
>such a question, Stan's answer would probably make the most sense. -vic
I took it as someone who was thinking of owning or who did own. Sorry you
didn't like my answer, but then, that's right, I didn't run it by you before I
posted it, did I?
Born2fly
Living the Dream
Arnold Christensen
pilots just what the rotor does as I goes into negative G's which
generally will result in mast bumping and then the mast breaks off about
a foot below the trunnion and departs the aircraft after one of the
blades takes out half of the left seater in a Huey. Very destictive
appearance to the intact rotor system on the ground.
Chris the Bigfoot
Joe Norris
>to minimize vibration.
Quite true. Fact is, when we do a T&B, we get the blades tracking as near
perfect as we can, and by the time we get them balanced to the lowest
vibration level, they're not nearly tracked anymore. The object of the game
is to get the vibration level as low as possible. Track will never be 100%
perfect (or at least I've never seen it 100% perfect).
Joe Norris
CBM522
impossible to exactly duplicate blades, they will have slightly
different stiffness, weight, etc. The blades on a Bell 412 aren't
even in the same plane to start with. I have never seen a ship with
all the blades all flying in exactly the same path. Very often, you
can see that the blades are out of plane, but there is no significant
You are absolutely correct about not getting all blades in the same plane,
however, you can get them very close. On the UH-60, prior to entering the
flight portion of the track and balance procedures, the requirement is to bring
the blade track to within 1/2 inch of each other. This is accopmplished after
the rotor head balance is adjusted to less than .20 IPS (inches per second)
Squeaks
CBM522 wrote in message <19990213001635...@ng-fd1.aol.com>...
>Actually, you will never get them to fly in the same path. It is
>impossible to exactly duplicate blades, they will have slightly
>different stiffness, weight, etc
snip
>The object is to minimize vibration.
>
>
>You are absolutely correct about not getting all blades in the same plane,
>however, you can get them very close. On the UH-60, prior to entering the
>flight portion of the track and balance procedures, the requirement is to
bring
>the blade track to within 1/2 inch of each other. This is accopmplished
after
>the rotor head balance is adjusted to less than .20 IPS (inches per second)
We find that it is more efficient to get the track as close as possible,
then start on balancing, but the two do tend to get done concurrently. If
the hover figures are so bad that they have to be adjusted before the
helicopter can get flying, balance may precede tracking, but a good tip path
plane will often be needed before weight, pitch link and sweep adjustments
are commenced.
My experience has been that track & balancing is the most time consuming
exercise going, but can reap enormous dividends in helicopter reliability.
We have progressed from the good old (?) flag tracking, through carrying a
strobe whilst on 4 hour trips and giving the guesstimate to the black hand
gang to interpret, and now we have very sophisticated computer units which
theoretically give all the solutions at once.
We aim for .2 ips or better, and currently run about .07 ips (at cruise) in
our B206's, and .05 ips in the A109. The 117 depends on the day of the
week, but usually manages .10 ips or better (the rigid rotor & composite
blades can take on a funny set if the weather changes, I reckon!).
I tried a new laser unit three weeks ago, which brought the tips within
millimetres of each other, but all the plots still required manual
interpretation. The only unit I've used that gave a decent computer
solution was the Chadwick 2000 (? don't flame me if I've got the wrong
number), but the program often didn't fit the helicopter. We had to use the
AS350 for the AS355, the 109 program didn't work, etc!
A good LAME is the only guarantee of a good solution, but ours tends to take
most of a day to achieve it! Mind you, the Sydney B206 had new TR blades
this morning, which came in 0.10 ips on the first run, so that leads to the
next important point, a good static balance.
All of which leads to a smoother flight, less maintenance problems from
vibration, and repeat customers who prefer our helicopters. Can't be all
bad,
Cheers,
John Eacott
The Helicopter Service Australia
Daniel L. Leclere
CountVoo wrote in message <19990208062842...@ng133.aol.com>...
>I read of ... "tracking and Balancing" the rotor blades.
>does anyone have references as to how this is done..and how typically best
>accomplished... i mean how does one "track" anything as a rotor blade thats
>flopping all over the place anyway?
"Prussian Blue"
Bring rotors up to speed and have some fool stand under the blade and lift
the stick
until it ticks on a blade.
When you shut down you will find a mark on the low blade.
Dan
HaroldA102
know how thay work??????