Today's Message Index:
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1. 05:44 AM - Dynamic prop Balance (Bill Morelli)
2. 07:41 AM - Re: Dynamic prop Balance (gary)
3. 01:11 PM - Re: Dynamic prop Balance (Bill Morelli)
4. 03:25 PM - Prop Pitch (The Meiste's)
Message 1
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Subject: | Dynamic prop Balance |
--> Stratus-List message posted by: "Bill Morelli" <billvt@together.net>
I finally had my propeller dynamically balanced.
The accelerometer for the measurement was bolted to the redrive unit using
one of the empty spreader bolt holes.
I had what felt like the most vibration at 3500 rpm. I told the A&P that
and he said that the best way to balance the prop was at full power but he
said we would check it at 3500 also.
Chained the HDS to a tractor so it would not take off during the full power
runups.
Full power runup was 4500 rpm (although it turns abouts 5100 in the air) -
The A&P (Phil) used a strobe bouncing off a reflector strip he applied to
one blade. He took a reading at full power (4500) and then one at 3500.
Both readngs came out the same - .6 (forgot what the units were) - The
reading needs to be down around .1 or less.
He added a 3/8" bolt through the spinner backplate (fiberglass) in line
with the heavy blade. The bolt was mounted with the head facing the engine
and threads sticking forward through the plate. Added 3 large flat washers
and a nut. This bolt arangement allows me to easily add or remove washers
in the future if I want to play with the balance. Just remove the spinner
and the nut and washers are right there. A wrench can be slipped behind to
hold the bolt head.
Performed another runup and it was better but not there yet. After four
iteratons of measurements and adjustments, the final weight was the bolt, 4
large washers, 1 small washer and the nut.
The engine is way smoother now than it ever was. I do have a slight drone
at 3500 rpm but I suspect that is a redrive phenomenon? Before I had a
pretty violent shake at 3500 rpm. Very smooth as I throttle up for takeoff
and also during cruise. I usually cruise at 4400 rpm. Should have had this
done sooner!!
Phil did also mention before we started that the blade picth is important.
If you do not have all the blades set to the same pitch it will cause
vibration. He has had cases in the past where adjusting the blade pitch
carefully has taken care of the vibration and has done away with the need
for a dynamic balance.
I have a couple of photos if anyone is interested.
Regards,
Bill (N812BM - HDS - Tri - Stratus (RAM Heads) - Vermont - 326.0 flight
hrs. - 448 landings, (1 ON ICE!!)
web site -> http://homepages.together.net/~billvt/
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Message 2
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Subject: | Re: Dynamic prop Balance |
--> Stratus-List message posted by: "gary" <FlyinK@Efortress.com>
good stuff Bill, glad it worked out for you.
i have trouble getting all 3 warp blades exactly the same. 2 will have the
bubble exactly in the center and one will have the bubble just touching one
line. warp said that was fine. also, my tracking is out on one blade about
1/4" which seems bad. before i mentioned how far out it was, warp said up
to 1/4" tracking is fine. these both seem unacceptable but it seems to work
pretty good.
i called the dyanamic balance company. he said it canbe balanced at any rpm
and it should effect all rpm's the same, which matches what you found Bill.
he also said that and out-of adjustment blade can be detected by seeing the
frequency of the vibration is every prop cycle but that didn't make sense to
me, i'll talk to him again.
i got a 72" warp prop, what's everybody else using? 70"? seems like 12
degrees is climb and 14 degrees cruise like I've heard before but i'd like
to try something like 10 and 16 to check the extremes. still shopping for
an in-flight adjustable and figured that'll give me an idea of what i could
expect for max climb and cruise.
gary
----- Original Message -----
From: "Bill Morelli" <billvt@together.net>
Subject: Stratus-List: Dynamic prop Balance
> --> Stratus-List message posted by: "Bill Morelli" <billvt@together.net>
>
> I finally had my propeller dynamically balanced.
>
> The accelerometer for the measurement was bolted to the redrive unit using
> one of the empty spreader bolt holes.
>
> I had what felt like the most vibration at 3500 rpm. I told the A&P that
> and he said that the best way to balance the prop was at full power but he
> said we would check it at 3500 also.
>
> Chained the HDS to a tractor so it would not take off during the full
power
> runups.
>
> Full power runup was 4500 rpm (although it turns abouts 5100 in the air) -
> The A&P (Phil) used a strobe bouncing off a reflector strip he applied to
> one blade. He took a reading at full power (4500) and then one at 3500.
> Both readngs came out the same - .6 (forgot what the units were) - The
> reading needs to be down around .1 or less.
>
> He added a 3/8" bolt through the spinner backplate (fiberglass) in line
> with the heavy blade. The bolt was mounted with the head facing the engine
> and threads sticking forward through the plate. Added 3 large flat washers
> and a nut. This bolt arangement allows me to easily add or remove washers
> in the future if I want to play with the balance. Just remove the spinner
> and the nut and washers are right there. A wrench can be slipped behind to
> hold the bolt head.
>
> Performed another runup and it was better but not there yet. After four
> iteratons of measurements and adjustments, the final weight was the bolt,
4
> large washers, 1 small washer and the nut.
>
> The engine is way smoother now than it ever was. I do have a slight drone
> at 3500 rpm but I suspect that is a redrive phenomenon? Before I had a
> pretty violent shake at 3500 rpm. Very smooth as I throttle up for takeoff
> and also during cruise. I usually cruise at 4400 rpm. Should have had this
> done sooner!!
>
> Phil did also mention before we started that the blade picth is important.
> If you do not have all the blades set to the same pitch it will cause
> vibration. He has had cases in the past where adjusting the blade pitch
> carefully has taken care of the vibration and has done away with the need
> for a dynamic balance.
>
> I have a couple of photos if anyone is interested.
>
> Regards,
> Bill (N812BM - HDS - Tri - Stratus (RAM Heads) - Vermont - 326.0
flight
> hrs. - 448 landings, (1 ON ICE!!)
> web site -> http://homepages.together.net/~billvt/
>
> |
> ---=( )=---
> 0 0
>
>
Message 3
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Subject: | Re: Dynamic prop Balance |
--> Stratus-List message posted by: "Bill Morelli" <billvt@together.net>
Gary,
I have a 70" warp drive and at present it is pitched to 15 degrees.
In the beginning I started way down around 12 degrees but I had so much
climb that I started working my way up. The 15 degrees seems to be just
about right for me. I wanted to get as much speed as possible yet still
have adequate climb.
I wouldn't mind having an in flight adjustable either but I'm not sure I
can justify the cost. There is also a weight penalty that you have to
consider.
Regards,
Bill
> i got a 72" warp prop, what's everybody else using? 70"? seems like 12
> degrees is climb and 14 degrees cruise like I've heard before but i'd like
> to try something like 10 and 16 to check the extremes. still shopping for
> an in-flight adjustable and figured that'll give me an idea of what i
could
> expect for max climb and cruise.
Message 4
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--> Stratus-List message posted by: "The Meiste's" <meiste@essex1.com>
Gary,
My prop is the same as Bill's. My original pitch setting was 12.5 deg. That
had a very nice climb, but a little slow on cruise. Also my 601 HD did not
want to land even at idle with that pitch setting. The unbelievable thrust
it produced just keep pulling me down the runway (just about had to turn the
key off to get the thing to stop flying). I have since changed it to 15.5
deg and this has greatly helped my landings, also cruise went up about 10
MPH. I would now like to see just a little better climb so my next change
will be back to 15 deg (my guess this would be about right for a 601).
Kelly
601 HD (86 hours)
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