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Mark Landoll Harmonic Dampener question

OneTwoSierra

Well Known Member
A buddy loaned me a Mark Landoll Harmonic Dampener to try. I have a catto 3-blade prop, so I'm not really expecting a ton of benefit from vibration, but I it'll get me closer to forward CG. Maybe I'll get better idle or more static RPMs.

Is there anything I need to know before I just bolt this on and go flying? I haven't heard much about them lately, and I was just wondering if they've fallen out of favor for some reason.

I have scales, so I'll know exactly what the CG impact.

Thanks in advanced,
 
watching this one

Hope you get some replies on this one, I am wondering the same thing.. is the CG that bad ?


Danny..
 
Careful......

Brian,
We have a 6A with a three-bladed Catto and the CG is fine with two people, full gas and no baggage. You won't get any more static RPM because the pitch determines that but maybe a smoother idle. Ours idles smooth already and I don't want to add any more weight to the airplane (It came in at 1046 lbs unpainted). A slightly rearward cg will increase your speed since a little 'down' elevator supporting some of the airplane's total weight is taken OFF the wing for a lower angle of attack. I intentionally fly with an aft CG when I can for that reason and we get 202 MPH true with two aboard and full fuel.(205 solo). Wife and I weigh 190 and 135.

It's only when you have a very far aft CG with baggage that the CG will move even further aft as the fuel burns and the elevator will become more sensitive and lighter but that's not a biggie either, if you're still in the balance envelope

It seems to me that you think you have a problem when you really don't. Keep the airplane light and don't spend bucks on things like harmonic balancers if you don't need them. After all, how many other Lyc powered airplanes carry them around?

One caveat though. Don't go doing spins with a very far aft CG or any other maneuver that might cause a spin.
Regards,
 
godspeed said:
Hope you get some replies on this one, I am wondering the same thing.. is the CG that bad ?


Danny..

No, my CG isn't bad. I just want to really load her up for OSH. With my 220 lb. wife and my 125 ib. self (just kidding, Pierre cracked me up.), we can carry a ton, but just not a ton in the baggage compartment. If I had more weight up front, I could get away with over 100 lbs in the baggage compartment that I might need going to OSH.

So just so no one misunderstands, I'm really thinking about trying this thing just to see what it's like -- I really don't have any particular issue I need to solve.

And, to answer an earlier post, some have claimed 75 to 100 more static RPMs with these things due to the smoothing of the engine and absorbtion of the pulses. I have no way of knowing if that's true or not yet.
 
Let us know when you test it :)

I would love to know how things work out when or
if you test it, I don't plan on going over the 75lbs in the baggage, my plan is board shorts, superman teeshirt & flipflops headed to the keys :) maybe a hangin shirt for going out to eat at night :) 2 or 3 lbs
but thats just me dreaming, anyway hope ya'lls wife
doesn't see that post.. how old did you say they were :) just kidding.. I am divorced so I can tease like that.. after 20 years of marriage..

Danny..
 
I have a 7A with a Performance wood prop and a Landoll Dampener. My plane came in at 1067 w/o paint and interior. I flew 20 hrs w/o the damper and the prop / engine combo was smooth running. The only changes I saw when I put the damper on was the ability to idle at 650 RPM vs 700, smoother idle, and the prop does not "slam" to a stop on shut down. I haven't noticed much difference in cruise...

I weigh 265 and with a friend who is 220 the extra weight in front does help the CG loading when baggage is carried. I set my gross at 1900 since I have fat friends... :)

Are the changes worth the money? Probably not....
 
Would like to communicate with anyone who is or has used a Landoll Harmonic Dampener. Post, PM or phone.

Thanks.
 
Pierre,
Lucky you got that corrected.....

I see Larry came down with his damaged 9A... such a shame...to have a hanger door come down on the wing...

He like the RV4 with the UL.

Hope your doing well
Jack
 
Had Landoll on O-320 RV-4 with MT fixed pitch. The prop was very light. Landoll ring smoothed out power pulses, and made it idle smoother. Previously, I could feel every cylinder fire... I didn't figure that was good for the mount either...
I'd do it again...

DM

I have a 7A with a Performance wood prop and a Landoll Dampener. My plane came in at 1067 w/o paint and interior. I flew 20 hrs w/o the damper and the prop / engine combo was smooth running. The only changes I saw when I put the damper on was the ability to idle at 650 RPM vs 700, smoother idle, and the prop does not "slam" to a stop on shut down. I haven't noticed much difference in cruise...

I weigh 265 and with a friend who is 220 the extra weight in front does help the CG loading when baggage is carried. I set my gross at 1900 since I have fat friends... :)

Are the changes worth the money? Probably not....
 
But is there proof (not just theory) that the Landoll does anything extra special to smooth out the power pulses, compared to a solid ring of similar mass?

My o-320 wood propped RV-4 was originally built with a Landoll. The builder eventually removed it in favor of a solid 12 pound inertia ring. He perceived no difference, so stuck with the more simple solid ring.
 
Mine was the solid ring. He had both available, and my understanding (from Mr Landoll) was wood props only needed the low tech version. It just added a bit a mass to the prop arc, which smoothed it out. Without it, for example, the prop would stop instantly when shut down. (not specifically WHY I used it, but an indicator of how it reacted)
I installed it because I didn't like the "bang bang bang" of the power pulses at idle... Even in the pattern at idle it did it. (MT prop weighed almost nothing) Metal props would NOT have this issue...
It did not slow down engine acceleration or deceleration at all. (very fast response with light prop)
The hollow ring, with the material inside it, was for prop balance issues as well as the harmonic component.
I liked the product. It did exactly what he said it would.

Hope this helps...
 
Would like to communicate with anyone who is or has used a Landoll Harmonic Dampener. Post, PM or phone.

Thanks.

I installed one on my mustang ii not too long ago strictly for w&b reasons. It weighs 11 pounds and bolts to the flywheel. I did not notice any difference in vibration or smoothness but it allowed me to be able to carry baggage. The bolt heads are very close to the starter so if one ever comes loose, it's going to be a bad day for sure. Overall I am happy with it. My M2 has an o320 and sterba wood prop.
 
I also have a Catto 3 blade prop. Do you by any chance have instructions for installation? I know the dampener bolts to the ring gear but I also have a steel plate that seems to belong on the front of the dampener with the center against the ring gear. However, talked to Mark Landoll and he said it had something to do with the spinner. My guess is I wasn't communicating very clearly.

Wally
 
Do not exceed 100 lbs in baggage compartment.

No, my CG isn't bad. I just want to really load her up for OSH. With my 220 lb. wife and my 125 ib. self (just kidding, Pierre cracked me up.), we can carry a ton, but just not a ton in the baggage compartment. If I had more weight up front, I could get away with over 100 lbs in the baggage compartment that I might need going to OSH.

So just so no one misunderstands, I'm really thinking about trying this thing just to see what it's like -- I really don't have any particular issue I need to solve.

And, to answer an earlier post, some have claimed 75 to 100 more static RPMs with these things due to the smoothing of the engine and absorbtion of the pulses. I have no way of knowing if that's true or not yet.

Pretty sure Van's says not to go over 100 lbs in Baggage compartment regardless of CG. The baggage compartment floor is only designed for 100 lbs.
 
I also have a Catto 3 blade prop. Do you by any chance have instructions for installation? I know the dampener bolts to the ring gear but I also have a steel plate that seems to belong on the front of the dampener with the center against the ring gear. However, talked to Mark Landoll and he said it had something to do with the spinner. My guess is I wasn't communicating very clearly.

Wally

I did not have any extra plates, just the ring and handful of bolts and nuts.
 
Landoll Balancer

I have the harmonic balancer on an O-320 with Aymar-DeMuth wood prop. No extra plates, very smooth running, helps with 6 CG. Have about 60 hours, cannot compare, always had the balancer on.

Mike
 
Mine was the solid ring. He had both available, and my understanding (from Mr Landoll) was wood props only needed the low tech version. It just added a bit a mass to the prop arc, which smoothed it out. Without it, for example, the prop would stop instantly when shut down. (not specifically WHY I used it, but an indicator of how it reacted)
I installed it because I didn't like the "bang bang bang" of the power pulses at idle... Even in the pattern at idle it did it. (MT prop weighed almost nothing) Metal props would NOT have this issue...
It did not slow down engine acceleration or deceleration at all. (very fast response with light prop)
The hollow ring, with the material inside it, was for prop balance issues as well as the harmonic component.
I liked the product. It did exactly what he said it would.

Hope this helps...

I installed one on my mustang ii not too long ago strictly for w&b reasons. It weighs 11 pounds and bolts to the flywheel. I did not notice any difference in vibration or smoothness but it allowed me to be able to carry baggage. The bolt heads are very close to the starter so if one ever comes loose, it's going to be a bad day for sure. Overall I am happy with it. My M2 has an o320 and sterba wood prop.
Mark is an active member of our EAA chapter (EAA UL98). He discussed his dampener with me prior to my build completion once I told him I was installing a 3-blade Catto prop. He had mentioned all of the issues posted here and others as to why I would need a dampener. My prop weighed in at 12 lbs. the Sabre spacer weighed in at 8.5 lbs. I decided against adding the plate as it would have added additional weight on the nose of my 'A' model. The very place I could least afford to have more weight. Might I say the least of which anyone building an 'A' model could afford additional weight. in 5.5 years of flight I have never missed it. The Catto is extremely smooth. It does not BANG-BANG-BANG at shutdown. It idles smoothly with no noticeable pulsing. The prop/engine does not display any of the negative aspects that others have reported.

I am happy with the decision I made in NOT installing additional weight on the nose with Mark's dampener. I personally think it a bit crazy to strive toward building as light as possible and then throw some chunk of metal or some such item to add weight and increase the weight and alter the C/G after carefully building light and balanced.

I also have a Catto 3 blade prop. Do you by any chance have instructions for installation? I know the dampener bolts to the ring gear but I also have a steel plate that seems to belong on the front of the dampener with the center against the ring gear. However, talked to Mark Landoll and he said it had something to do with the spinner. My guess is I wasn't communicating very clearly.

Wally
If you have not already flown with the Catto 3 blade prop I suggest you do so before installing Mark's dampener. As I attest above my experience with my 9A is that with the Catto 3 blade it is not needed.
 
May just do that. I bought from a friend who had a 4. He added not only the harmonic dampener but a 12 lb steel ring to get is CG where he could stay within envelope with a rear seat passenger. I also have the steel ring but do not plan to add that until and if it is deemed necessary. The steel plate I have is a total ?????

He sold his -4 to a guy who planned to use a metal prop so they removed it before sale. Unfortunately, he is now suffering from dementia so unable to answer my question.
 
Thanks Steve! I think I will go with your suggestion. My guess is that the CG on an A model is not as big an issue as on a 4.

Talked to Mark but he was not able to help with the steel plate. Could well have been my communication. Was great to talk to him! Met him at Oshkosh probably 15 years or so. Also talked to Inovators West, who manufactures them but they have never seen on installed on an aircraft. Big in racing engines.

Wally
RV-4 getting close!
 
My 6 was built with the solid ring and originally an Aymar-Demuth wood prop. I left the ring on when I installed the Sensenich GA prop because I need the weight up front for CG reasons. It sure is smooth with this prop, like "turbine smooth". I like it.
 
Thanks Steve! I think I will go with your suggestion. My guess is that the CG on an A model is not as big an issue as on a 4.

Talked to Mark but he was not able to help with the steel plate. Could well have been my communication. Was great to talk to him! Met him at Oshkosh probably 15 years or so. Also talked to Inovators West, who manufactures them but they have never seen on installed on an aircraft. Big in racing engines.

Wally
RV-4 getting close!
You may be surprised at how smooth Catto props are just bolting them on and flying. They are indeed a work of art!
 
Wally,

The steel plate you have is the "Aerobatic Plate".

I had a Landoll Harmonic Balancer with the aerobatic plate on my -4 which I flew for 10 yrs before selling.

The aerobatic plate attaches to the front of the balancer and behind the prop hub and will bolt to the ring around it's perimeter. I believe the point is to strengthen the balancer by sandwiching it that way.

I think it was a good addition but no scientific evidence.

Glenn
 
The -7 is a different story

I have the landoll ring and the sabre steel spacer with a Catto 3 blade prop on my -7 primarily for the CG reasons mentioned in this (and other threads)

The -7 tends toward aft CG with two up and 100lbs of baggage as the CG moved aft with fuel burn. The -7 was targeted for a typical Hartzell CS prop which weighs 40+ lbs and my original sensenich metal prop assembly weighted 42lbs. When I switched to the Catto which weighs about 12 lbs it made a big difference to the W&B calculations if fully loaded as the weight all came off the nose. In my case I went with the landoll and sabre crush plate rings to put the weight back on and I have not regretted the decision, the Catto is very smooth anyway but my motor also runs smoothly at 800 rpm at idle.

As far as the CG/W&B last year we had two big guys and full camping gear etc for oshkosh and we were good down to 10 gals inside the aft CG limit which is good for 4 hour legs (at which I would need a bio break anyway)

Like everything on the RV there are many choices and I am happy with mine.
Figs
 
Round disc needed?

I have a Landoll Balancer with the bolts and a round disc that seems to fit over the entire unit after it's bolted to the flywheel. The disc has small holes that correspond to the prop hub bolt pattern.

I seen pictures of Landoll installations that did not include this disc and another that did.

I don't have any instructions on the Landoll installation or the disc, can anyone help me understand it's purpose and if it's needed.

Thanks, Steve Briggs
 
Round disc needed

I have a Landoll Balancer with the bolts and a round disc that seems to fit over the entire unit after it's bolted to the flywheel. The disc has small holes that correspond to the prop hub bolt pattern.

I seen pictures of Landoll installations that did not include this disc and another that did.

I don't have any instructions on the Landoll installation or the disc, can anyone help me understand it's purpose and if it's needed.

Thanks, Steve Briggs
 
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