Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
As Smooth as Possible
- Thread starter istrumit
- Start date
Carl Froehlich
Well Known Member
Porting will not make a measurable difference.
If you always run ROP, balancing the injectors will not make a big difference.
If you run LOP (as I do), then balancing is required. I changed out 4 of the 6 injectors - so a little over $100 to get a gami spread to go from 1.5 gph to 0.1 gph.
Prop balancing should be the first thing you do. Your cowl hinges will thank you as well.
Carl
If you always run ROP, balancing the injectors will not make a big difference.
If you run LOP (as I do), then balancing is required. I changed out 4 of the 6 injectors - so a little over $100 to get a gami spread to go from 1.5 gph to 0.1 gph.
Prop balancing should be the first thing you do. Your cowl hinges will thank you as well.
Carl
David Paule
Well Known Member
Prop balance first.
Dave
Dave
Carl Froehlich
Well Known Member
A lot of A&Ps do this, but many EAA chapters now own one of the new style prop balancing analyzers. Recommend you ask around.
Carl
Prop
If you strike out elsewhere the closest prop shop may do on aircraft balancing. I believe that Lycoming for quite a while now has been doing a better job of internally balancing the engine.
Almost all of the custom engine builders do a very precise job of balancing engine internal components.
If you strike out elsewhere the closest prop shop may do on aircraft balancing. I believe that Lycoming for quite a while now has been doing a better job of internally balancing the engine.
Almost all of the custom engine builders do a very precise job of balancing engine internal components.
Not likely to help. A 3-blade prop on a 6-cylinder engine beats like a 2-blade prop on a 4-cylinder engine. That's why 3-blade Catto's run so nicely on O-320's and O-360's, the number of blades isn't an integral multiple of the cylinders.
For a 6-cylinder engine, you'd need a 4-, or even better a 5-, blade prop to smooth out the prop-to-cylinder ratio. But by that point you're losing a lot of efficiency in your propulsion... Might look cool though...
SDS EFI/EI with individual fuel trim control. Available first week in October for 6 cylinder engines. Can get the same AFR in each cylinder at any rpm and MAP setting without flight testing, removing the cowling and trying different nozzles. All at the touch of a few buttons from in the cockpit with the EFI.
The idle is also noticeably smoother than mechanical injection due to superior fuel atomization and metering.
The high energy spark from the EI will reliably light mixtures leaner than 18 to 1 and with total advance adjustability, allows you to optimize the PCP for max fuel economy at any mixture setting.
The idle is also noticeably smoother than mechanical injection due to superior fuel atomization and metering.
The high energy spark from the EI will reliably light mixtures leaner than 18 to 1 and with total advance adjustability, allows you to optimize the PCP for max fuel economy at any mixture setting.
snopercod
Well Known Member
Lancair fleet with IO-550 engines had a generic vibration problem, or still has. The factory, LOBO, Hartzell, and Lord spent a lot of engineering hours trying to figure it out. To make a long story short, Lord came up with different mounts for the front and back that solved the problem. I have no idea is this information is applicable to your problem, but here it is:
The full story is available at the Lancair Owners and Builders website.
The full story is available at the Lancair Owners and Builders website.
istrumit
Well Known Member
On thing I thought I should say, after thinking about it.
The vibration is small...just enough to trip my OCD..
And, here is the key part...
I does *not* seem to change with RPM.
So, maybe I have a wheel pant fluttering ? I do have a wheel that vibrates on taxi, so maybe I have shaken the wheel pant loose a bit.
The vibration is small...just enough to trip my OCD..
And, here is the key part...
I does *not* seem to change with RPM.
So, maybe I have a wheel pant fluttering ? I do have a wheel that vibrates on taxi, so maybe I have shaken the wheel pant loose a bit.
Flying in a plane that hasn't had the prop balanced is like riding in a car that hasn't had it's tires balanced.
Also takes stress off of airframe and engine parts with reduction in vibration.
Best bang for the buck for a perceivable improvement in smoothness.
check out www.jimjeffriesairworks.com dynamic prop balancing.
He is located in Mississippi but travels all over the country and TN not that far away if you feel like a short hop or he may be traveling through your area. His credentials speak volumes and I can vouch for his work. Visit the web site if you want to see some sweet planes he has worked on.
Guess you could say I'm a fan.
Also takes stress off of airframe and engine parts with reduction in vibration.
Best bang for the buck for a perceivable improvement in smoothness.
check out www.jimjeffriesairworks.com dynamic prop balancing.
He is located in Mississippi but travels all over the country and TN not that far away if you feel like a short hop or he may be traveling through your area. His credentials speak volumes and I can vouch for his work. Visit the web site if you want to see some sweet planes he has worked on.
Guess you could say I'm a fan.
Last edited:
That's not correct in my experience
I've flown a number of planes and the three blade is always smoother. My three blade MT IO-540 is orders of magnitude smoother than my buddy's two blade Io-540.
Also it helps if Barrett Engines massages the engine first.
My IO-540 and three blade is so smooth that the guys on the airport say they can always tell it's my RV-10 because of the silky sweet smoothness.
I've flown a number of planes and the three blade is always smoother. My three blade MT IO-540 is orders of magnitude smoother than my buddy's two blade Io-540.
Also it helps if Barrett Engines massages the engine first.
My IO-540 and three blade is so smooth that the guys on the airport say they can always tell it's my RV-10 because of the silky sweet smoothness.
Not likely to help. A 3-blade prop on a 6-cylinder engine beats like a 2-blade prop on a 4-cylinder engine. That's why 3-blade Catto's run so nicely on O-320's and O-360's, the number of blades isn't an integral multiple of the cylinders.
For a 6-cylinder engine, you'd need a 4-, or even better a 5-, blade prop to smooth out the prop-to-cylinder ratio. But by that point you're losing a lot of efficiency in your propulsion... Might look cool though...
Last edited by a moderator:
I suppose I over-stated that a bit... On two otherwise identical setups, three blades will be smoother than two, yes, but you could get even smoother if you increased the blade count so the piston to blade ratio wasn't an integer.I've flown a number of planes and the three blade is always smoother. My three blade MT IO-540 is orders of magnitude smoother than my buddy's two blade Io-540.
Also it helps if Barrett Engines massages the engine first.
My IO-540 and three blade is so smooth that the guys on the airport say they can always tell it's my RV-10 because of the silky sweet smoothness.
As you confirmed, careful static balancing of the engine and prop separately, and then dynamic balancing of the entire system, will probably get you so close to smooth you wouldn't notice the improvement with more blades.
I use the Dynavibe balancer and routinely get down to .01-.03 IPS. My RV-10 with a 3 blade MT is at .01 IPS and it is noticeably smoother than 2 blade RV-10's I have flown. So much so that you start to notice other things making noises!
Vic
Vic
istrumit
Well Known Member
If the engine is very, very smooth, I will be able to hear/feel changes in the plane very easily, which is exactly what I am after ("other things making noises")
