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Propeller Dynamic Balance Questions

db1yg

db1yg

Well Known Member
Howdy,

A couple of questions to those of you who have experience with dynamic balancing of constant speed propellers:

1. When selecting an rpm for the balance run, should we avoid the 2050 to 2300 rpm range on the Lyc IO360 4 cylinder due to the harmonics--or is this not relevant??

2. When selecting an rpm for the balance run, should we use our typical cruise rpm -- for example my typical cruise is at 2350 rpm and full throttle for my 180/Whirlwind RV200.

Thanks in advance for any advice.

Cheers,

db
 
2350

Dave,
I am pretty sure the instructions say to shoot for cruise RPM. So 2350 for you.

Note: the balancing enviroment can be extreme. Sitting in the cockpit with your prop spinning 2350 is a little un-nerving...so be prepared for it.
Tying the tail to a tie-down or a truck hitch is a good idea. Along with chocks as usual. The empenage is subject to the prop blast bouncing it around, so it is not a smooth ride.
 
Thanks Bob

Hey Bob,

And if I go to 2350 the harmonic tendency is eliminated since Lyc says the worst of it occurs at 2050 to 2300.

All the best and of course,

Cheers,

db
 
db1yg said:
Howdy,

A couple of questions to those of you who have experience with dynamic balancing of constant speed propellers:

1. When selecting an rpm for the balance run, should we avoid the 2050 to 2300 rpm range on the Lyc IO360 4 cylinder due to the harmonics--or is this not relevant??

2. When selecting an rpm for the balance run, should we use our typical cruise rpm -- for example my typical cruise is at 2350 rpm and full throttle for my 180/Whirlwind RV200.

Thanks in advance for any advice.

Cheers,

db
Click to expand...

#1 not relevant.
#2 I balance em at 2350-2400 generally, you won't need full throttle on the ground.
 
Static vs cruise rpm?

I can?t get to cruise rpm on the ground with 160hp/sensenich fixed. Do you tune to max attainable?
 
I do it at cruise rpm and Manifold Pressure high enough to achieve cruise RPM with the prop pulled off the stops (knob out a little).
 
Jesse said:
I do it at cruise rpm and Manifold Pressure high enough to achieve cruise RPM with the prop pulled off the stops (knob out a little).
Click to expand...

Hi Jessy what is the reasoning to do it just off the stops?
Is that to make sure blade angle is the same???
 
db1yg said:
Howdy,

A couple of questions to those of you who have experience with dynamic balancing of constant speed propellers:

1. When selecting an rpm for the balance run, should we avoid the 2050 to 2300 rpm range on the Lyc IO360 4 cylinder due to the harmonics--or is this not relevant??

2. When selecting an rpm for the balance run, should we use our typical cruise rpm -- for example my typical cruise is at 2350 rpm and full throttle for my 180/Whirlwind RV200.

Thanks in advance for any advice.

Cheers,

db
Click to expand...

My RV200 prop was not statically balanced well enough
And due to this i was unable to balance dynamicly as good as i wanted
Some RPM ranges were really off balance
After i statically balanced it. And did dynamic balance again
It was like jet engine in all rpm ranges
This is all to say that if your static is done good and you lucky
You will get smooth prop regardless of cruise rpm or not
 
rjcthree said:
I can?t get to cruise rpm on the ground with 160hp/sensenich fixed. Do you tune to max attainable?
Click to expand...

Yes max static in your case. In reality if its well balanced at 2100 then it won't change much at the higher RPM's.
 
Dynamic Prop Balance

Got it done!! IO360-RV9a with a WW RV200. It took 3 runs--one baseline, one with initial wt added, and last with final wt. The baseline showed 0.331 ips, second run was 0.24 ips, and the third was 0.0571 ips--we stopped there. Just as had been recommended by several of you, we ran it at my normal cruise rpm of 2350 with the prop off the stop. I actually ran it up to 2400 and used the prop control to bing it back down to 2350 with the mixture leaned. All runs were at the same rpm, prop setting, ff, and mp.
Worked out well. Thanks to all for the suggestions.

Cheers,

db
 
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