Prop Balancing Pirep

Jay Honeck

Jay Honeck

Touchdown! Greaser!
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Jay Honeck
We flew up to Dallas from the island today, to have the prop balanced on our new (to us) RV-8A, "Amelia".

First, let me say that flying to Dallas, chock to chock, in just two hours, was AMAZING -- but I digress. :D

My first RV-8 ride was in Jay Pratt's amazing aircraft. This plane had an almost turbine-like smoothness that impressed me. When we trained in Amelia, I noticed immediately that she was about as smooth as Atlas, our Piper Pathfinder, (which has been fine for 11 years), but nowhere near as smooth as Pratt's RV.

So, I found Walt's place, EXPAircraft (http://expaircraft.com) the Van's RV website. He came highly recommended as one of the best in the prop balancing business. In a previous life, he worked balancing jet engines for the airlines, and his techniques were honed by many years of practice on DC-10s.

Walt is located at Roanoke, TX (52F) a suburb of Dallas. It's an amazingly active little field, with a good on-field restaurant (the Blue Hangar Restaurant), and a full-blown pilot's shop. General Aviation is alive and thriving in the Dallas area, for sure.

The balancing procedure is deceptively simple. Decowl the engine, put a piece of reflective tape on the prop, and mount a laser on the engine.

Then mount a vibration sensor on the engine, outboard. These two different sensors connect to a handheld computer, where the magic happens.

Step One, run the engine up to 2300 RPM. This is the first run, and Walt hangs some weight on the flywheel at the stations prescribed by the magic handheld computer.

Step Two is the second run. Again, I ran it up to 2300 RPM, and it was immediately apparent that something wonderful was happening. Vibration in the stick, and through my butt, was easily halved.

Step Three, again after hanging more weights at the prescribed locations, was the third run, where the balance is fine tuned.

The third run was...amazing. I just sat there, and nothing shook. Like, at all. It was just sound, and no motion. It was truly amazing.

According to Walt the initial run showed my prop at .018. Apparently .02 is the upper limit of vibration recommended, so our prop was close to the max vibration normally seen.

By the third run, Walt had it reduced to .007, close to perfect. It was an amazing change, night and day, really, and I couldn't be happier.

The flight home was remarkable. We climbed to 11,500', in typical RV fashion (quickly), without any vibration at all. It was almost creepy, but wonderful at the same time.

Best $175 I've ever spent on an airplane. Just do it.
 
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Walt is the best in the business, IMHO. I have called on his experience many times. I worked with him on the restoration of the RV-1.

Glad your balancing went so well! It is amazing to me that all plane owners don't spend the $$$ to make their plane more smooth, enjoyable, safer, less oil leaks, engine lasts longer, and the plane is FASTER! :yes: . Electronics last longer and so does the airframe! :eek:

(In theory a well balanced engine & prop is putting less energy into vibrating the airframe. ;))

.018 IPS is pretty rough, .007 IPS is amazing!

http://www.rpxtech.com/rpxweb/Dynavibe-WhyBalance.asp

If you own a plane, get it balanced. Would you drive on unbalanced tires? Then why would you fly an airplane with the prop & engine not balanced? :mad2:
 
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Agree with both Jay and Geico...........

Prop balancing is the fastest and cheapest way to enhance the quality of your plane...... My local head of maintenance , Todd@ JHA is a perfectionist and loves to balance props... And he is GOOD at it too.. I get the benefit as they use my plane for teaching sessions for new mechanics so I get the " cousin " rate...;):)..

Ps.. Any balance job will help, you can pick out the true experts as they are the ones who will use the split weight correction...

Pss... We can get my prop to within .01 if the wind is not blowing as that effects the balance job... I have never heard of the IPS going into the .007 range.... That guy must have some pretty fancy equipment...:yes:
 
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So for the faster claim, have there been any noticable differences changes in speed?
 
Ted DuPuis said:
So for the faster claim, have there been any noticable differences changes in speed?
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Not in my case, but I only have the single flight to use as comparison. The theory makes sense, but will it be noticeable?

Regardless, the plane is simply better, after balancing. The RV-8 is a joy to fly, and now it's even better.
 
I'd not exppect any change in speed that could be quantified. The amount of horsepower it takes to cause vibration is quite small. Where I'd expect to see the benefit is in fewer vibration-related maintenance items and, as you mention, more enjoyment in flying.
 
Jay Honeck said:
Not in my case, but I only have the single flight to use as comparison. The theory makes sense, but will it be noticeable?

Regardless, the plane is simply better, after balancing. The RV-8 is a joy to fly, and now it's even better.
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Not really. In theory more energy is going into thrust.
 
Ted DuPuis said:
I'd not exppect any change in speed that could be quantified. The amount of horsepower it takes to cause vibration is quite small. Where I'd expect to see the benefit is in fewer vibration-related maintenance items and, as you mention, more enjoyment in flying.
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Here's a real-life example of "faster", with this plane.

A climb to 11,500' in a piston single, in temps approaching 100 degrees, is arduous. On the flight to Dallas, before balancing, (and all previous flights) we retarded the prop RPMs soon after departure because the noise level was so high. (A bubble canopy is like putting your head inside one of those parabolic reflectors the networks use to pickup the quarterback's signals from the sidelines. It's LOUD, even with Zulu ANRs.)

On the flight home, I was busy dealing with ATC, and simply forgot to retard the blue lever. Trust me, before balancing, there was no way to "forget"! Thus, our climb to 11.5 was quicker, simply by virtue of being able to leave the prop in climb pitch all the way up.

So, in that regard, balancing has made the plane "faster".
 
Geico266 said:
Not really. In theory more energy is going into thrust.
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Sure, but that energy is so small relative to what's required to increase speed that I highly doubt if you'd see a speed improvement.

Jay Honeck said:
Here's a real-life example of "faster", with this plane.

A climb to 11,500' in a piston single, in temps approaching 100 degrees, is arduous. On the flight to Dallas, before balancing, (and all previous flights) we retarded the prop RPMs soon after departure because the noise level was so high. (A bubble canopy is like putting your head inside one of those parabolic reflectors the networks use to pickup the quarterback's signals from the sidelines. It's LOUD, even with Zulu ANRs.)

On the flight home, I was busy dealing with ATC, and simply forgot to retard the blue lever. Trust me, before balancing, there was no way to "forget"! Thus, our climb to 11.5 was quicker, simply by virtue of being able to leave the prop in climb pitch all the way up.

So, in that regard, balancing has made the plane "faster".
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Right, but that didn't actually increase horsepower available through the balance.

But you do raise an interesting noise point, which I wouldn't have thought about. So one more thing to look for when we get it done on the 310.
 
FYI: I posted this PIREP on the Van's site, and Walt replied with the following technical corrections to my story:

"Just a few minor corrections to your numbers, initial vibration was 0.180 IPS with an upper limit of 0.200 IPS @ 2400 RPM."

"Final vibration level came in at an amazing low (lower than most) at 0.007 IPS (Inches Per Second)."

Obviously my technical knowledge of the process can be summed up as : "Ug. Me push blue lever forward, engine no shakey." -- but I trust y'all get the idea.
:D
 
Ted DuPuis said:
Sure, but that energy is so small relative to what's required to increase speed that I highly doubt if you'd see a speed improvement.



Right, but that didn't actually increase horsepower available through the balance.

But you do raise an interesting noise point, which I wouldn't have thought about. So one more thing to look for when we get it done on the 310.
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Theoretically, the plane with a balanced prop is faster.
 
I was thinking of getting this done on the 150. Feels much smoother at 2400 then it does at 2500-2600 climb or level. I called one prop shop at LNS and I think they quoted around $350.
 
One of the things I had done soon after buying the 'kota (long before it was Franken-) was have the prop overhauled and then dynamically balanced. Prior to balance, I only ran at 2,400 rpm for cruise 'cause things shook too much otherwise. Afterward, run at just about any reasonable rpm and things are fine.

The really good thing about it is that if you feel vibration now it's time to look at the engine 'cause something is wrong. That concept is a little hard to get used to.
 
Mike5250 said:
I was thinking of getting this done on the 150. Feels much smoother at 2400 then it does at 2500-2600 climb or level. I called one prop shop at LNS and I think they quoted around $350.
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Tell them to pound sand. $200 or less is the going rate, even at the big shops.
 
52F is like 15 min from me.... next time you're up here, lemme know and we'll connect for food. Some good eats are not that far from the runway in Roanoke.
 
AggieMike88 said:
52F is like 15 min from me.... next time you're up here, lemme know and we'll connect for food. Some good eats are not that far from the runway in Roanoke.
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Dang, sorry we missed you. We hooked up with Jay Pratt (he's based at Hicks; we bought a retractable sunshade for the canopy from him, after lunch) and Dan Reeve, the guy who runs the Van's Air Force website. It was a fun day.

Just landed after a dusk flight over the island. Dang, this thing is SMOOTH.
 
Jay Honeck said:
Dang, sorry we missed you. We hooked up with Jay Pratt (he's based at Hicks; we bought a retractable sunshade for the canopy from him, after lunch) and Dan Reeve, the guy who runs the Van's Air Force website. It was a fun day.

Just landed after a dusk flight over the island. Dang, this thing is SMOOTH.
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Pretty sure you meant Doug Reeves. ;)

Jay! You made the front page of the VAF news with your prop balancing pirep! :goofy:
 
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the biggest factor of having a balanced engine/prop, is pilot fatigue. plus noise is a large factor in that too
 
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