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tc1917(at)bellsouth.net
Guest

Posted: Fri Apr 10, 2009 3:29 am Post subject: harmonics

Thanks people.  Got a lot of good ideas to work with.  I might mention here 

that I have talked to WD about this problem before and I decided that having 

them send a set of props out and having to send them back used, was not a 

good solution. (they did not volunteer to do it) If I had more PROOF that 

this was the problem I would do it in a heart beat.  My friend down in 

Panama City has a new set to put on his slingshot 912 when it gets installed 

so if I used his, it is already set up for him.  Good for him.  Good for me. 

Good are to test it too.  Nothing like a casual stroll above the beach.  I 

thought about changing the vibration dampers, there are only four but which 

way?  Harder, softer.  Dont think I want that 912 wandering around up there 

hither and throw.  The way the mounts are, there is not much option.  I 

misphrased the CG problem with a four inch spacer.  I should have said it 

changed the flying and landing characteristics of the plane.  If it had 

worked, I would have kept it but it made it squirely.  You have to remember, 

this SS is very short coupled  and it seemed the prop being back that little 

bit affected everything, including torque on take off.  The two inch 

actually improved it.  Didnt really need one but I spent so much money on it 

and the four incher going back to kolb that I decided to keep it on.  The 

idea of listening tubes taped up everywhere for run up is a good idea, going 

to try that.  I also like the idea of taping up the leading edge of the 

blades.  That I can do without going to Florida.  But having a good reason 

to fly to florida is always a good idea.  So, I will keep on trucking and 

see if I can figure this out.  Oh, yeah, according to the gear box plug, 

there is absolutely no metal being eaten in there and I have almost a 

hundred and fifty hours on the engine.  Hauck was concerned that the gear 

box spacers were not right.  He still may be correct.  I WILL find the 

answer someday.  I do know that there are many others out there making the 

noise I have.  I am also going to check the compression.  Another good idea. 

I wonder, if it has a different cylinder comp., what do I do then?  Ted

jimh474(at)embarqmail.com
Guest

Posted: Fri Apr 10, 2009 4:41 am Post subject: harmonics

Ted;



When you went from the 582 to the 912, did you use the same lord mounts that 

you used for the 582?



If so this may be your harmonic problem.



Jim Hauck

slyck(at)frontiernet.net
Guest

Posted: Fri Apr 10, 2009 5:07 am Post subject: harmonics

Which would be more likely to be a cause, too flexible or too firm?

BB



On 10, Apr 2009, at 8:40 AM, Jim Hauck wrote:



 	  Quote: 	
		   



 Ted;



 When you went from the 582 to the 912, did you use the same lord  

 mounts that you used for the 582?



 If so this may be your harmonic problem.



 Jim Hauck

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sat Apr 11, 2009 3:46 am Post subject: Re: harmonics

If the harmonic is coming from some airframe part and is a result of engine/prop vibrations, then the engine/prop vibrations being transmitted to this airframe part would be lessened if the mounts were a little softer. In any case a change in mount stiffness would change the natural harmonic frequency which might make the current troubling sound go away, go to a different pitch, go to a different part of the airframe or get worse. Difficult to predict.



Assuming the prop is statically balanced, blades pitched equally, and tracked properly, the next step I would consider is dynamic engine/prop balancing. Doing so may solve your problem at the source, which would be the best solution. Many class D and bigger airports with reasonably complete maintenance shops have the capability to do dynamic engine/prop balancing. Last time I checked local prices it was about $250.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Sat Apr 11, 2009 4:50 am Post subject: Re: harmonics

You mentioned that John H. mentioned the gear box spacers, this makes several different people that I have heard mention this.  The others were not on the Kolb list, but it seems to be something important with the 912.   I am not sure what the symptom is if the spacing is out of tolerance, but I will ask.  The SS seems like an interesting plane, it would probably leave all of us behind.  What speed and and RPM 's do you use for both long range and high speed cruise ?  What are you approach and landing speeds ?



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

herbgh(at)nctc.com
Guest

Posted: Sat Apr 11, 2009 7:58 am Post subject: harmonics

I am Rebuilding a C box...I notice that the  input shaft and  prop 

shaft both have spacers/shims  ...They are important such that too 

much clearance  will allow hammering with throttle changes...This 

will result in an accelerated wear factor which will gradually affect 

the case...or enclosure.and bearings and gear lash.......Herb

At 07:50 AM 4/11/2009, you wrote:

 	  Quote: 	
		  



You mentioned that John H. mentioned the gear box spacers, this 

makes several different people that I have heard mention this.  The 

others were not on the Kolb list, but it seems to be something 

important with the 912.   I am not sure what the symptom is if the 

spacing is out of tolerance, but I will ask.  The SS seems like an 

interesting plane, it would probably leave all of us behind.  What 

speed and and RPM 's do you use for both long range and high speed 

cruise ?  What are you approach and landing speeds ?



Mike



--------

&quot;NO FEAR&quot; -  If you have no fear you did not go as fast as 

you could have !!!



Kolb MK-III Xtra, 912-S





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 38698#238698





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04/11/09 10:51:00

jbhart(at)onlyinternet.ne
Guest

Posted: Sat Apr 11, 2009 5:41 pm Post subject: harmonics

At 04:46 AM 4/11/09 -0700, you wrote:

 	  Quote: 	
		  



If the harmonic is coming from some airframe part and is a result of 

engine/prop vibrations, then the engine/prop vibrations being transmitted to 
	


this airframe part would be lessened if the mounts were a little softer. In 

any case a change in mount stiffness would change the natural harmonic 

frequency which might make the current troubling sound go away, go to a 

different pitch, go to a different part of the airframe or get worse. 

Difficult to predict.

 	  Quote: 	
		  

.........................
	


Just to add a few thoughts.  It all has to do with energy inputs.  The 

greater the HP and the lighter (less stiff) the air frame the greater the 

chance is for harmonic vibrations to develop.  Every air frame and or 

components will have some natural frequency.  But there is an energy input 

threshold that must be passed before the frame will resonate that is related 

to structural stiffness.   It is similar to unbalanced aileron flutter where 

a certain speed (energy level) must be reached before there is an onset of 

flutter.



So what is the driving energy force?  Well it is the engine and the 

propeller.  They cause a twisting in the mounts directly proportional to the 

average torque being developed.  Superimposed on top of the average torque 

is periodic torque variation that is caused by engine cylinder firing 

impulse.  The amplitude variation is dependent upon torque resistance 

(springiness) of the crank shaft and crankshaft load.  This load will be the 

gear box or propeller.  As one increases crankshaft load more and more of 

the torque variation must be transferred to the engine mounts and dissapated 

though the supporting structure.



So what are the choices?  One could add more cylinders for a given average 

torque, and this would reduce the torque variation component magnitude so 

that will not exceed the airframe threshold.  One can de couple the engine 

and propeller by moving to softer mounts.  One can back off the throttle a 

little and reduce the torque variation amplitude, and in doing so miss match 

frequencies.  This may also be accomplished by changing gear box ratios or 

changing the number of propeller blades.  



Another way to reduce the torque variation amplitude transmitted to the 

airframe is to add some kind of dampening in between the engine and the 

propeller.  Also one can reduce inertial load seen by the crankshaft (less 

twisting).  Just because an engine gear box or reduction unit can tolerate a 

certain level of propeller inertia does not mean that it is the correct or 

desired combination for all airframes.  By lowering propeller inertia for 

the same power output means lower energy dissipation to the air frame.  A 

more flexible the propeller will give further improvement, by absorbing some 

of the crank torque variation amplitude from the crank and there by not being

passed on to the airframe.



One last comment.  On the FireFly, I had some noise problems.  Streamlining 

the struts removed a constant bass strumming noise.  The Victor 1+ being a 

one cylinder engine, it shakes things a bit.  I found that it really excited 

the inboard aileron hinges.  When I took all the play from the aileron 

hinges and control system, things became quieter.  Also, I discovered the 

soft wing gap seal fluttered.  Tube stiffeners in the front and rear cross 

seams to care of it.



FWIW



Jack B. Hart FF004

Winchester, IN

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Sun Apr 12, 2009 5:38 pm Post subject: Re: harmonics

Perhaps this may be of interest. 

A fellow pilot friend of mine at our airport were talking this over the other day and he suggested that I try putting the plane into a slip to see what would happen. 



I finally got a small hole in the winds/storms today and went around the patch, I tried this on downwind a couple times in both directions. The rruurruurruurr part of the noise sure enough went away. With the pedal near the floor it was completely gone and there was just the higher frequency hum which I take to be the blades hitting the relative wind.



So in my case, I'm coming back to the conclusion more and more that I don't have a safety issue and it's probably ok. Fatigue, however, due to the increased thrumming I already know is an issue tho I may eventually get used to that too. But it's enough for me to keep working on it, I'm going to try a different prop type to see what happens.



PS I spoke to another owner of my model plane who runs the WD and he reports the same harmonics. He's running the 64" 3 blade taper tip (912ULS also) and is not concerned about it. 



So this may be a helpful diagnostic step to take in general (tho what exactly it tells you I'm not sure ). In my case, it smoothed out in a slip indicating there probably isn't any balance problem but it just has to do with that big ol airplane in front of it disturbing the airflow.



LS

_________________
LS
Titan II SS

tc1917(at)bellsouth.net
Guest

Posted: Mon Apr 13, 2009 5:47 am Post subject: harmonics

To answer a couple of questions:  I dont have any apparent slack in the prop 

to indicate a loose gear set or too much gear lash.  Might be a little too 

tight going around but not to the point it is grinding metal.  The motor 

mounts are the ones supplied by the Kolb Factory with the 912.  Took the 582 

ones off.    My normal cruise speed for the SS is around 82/85 indicated.  I 

can hit 90/95 in a heartbeat.  Been over a hundred a couple of times at only 

about 5400 rpm.  my set up and aproach is around 70 indicated with touch 

down somewhere around high 40s I think.  at 60 you are still pretty much 

flying although you have a sink rate.  My normal roll out is somewhere 

between 200 to 300 feet, close to take-off roll.  Once the feet are down, 

speed is lost very fast so there is not a lot of roll out.  If I go in slow, 

break it right away, I can stop in about 150 feet without even thinking of a 

nose over.  I love the tall landing legs and forward sweep.  Like I said, if 

it didnt make that awlful noise, I would have the perfect flying machine --  

although it looks a little strange!  When and if the wind and rain stops, I 

will get to work on those great suggestions.  I will let everyone know the 

results for the archieves.  Ted Cowan, Slingshot 912 ul.

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Mon Apr 13, 2009 6:21 am Post subject: Re: harmonics

 	  tc1917(at)bellsouth.net wrote: 	
		  To answer a couple of questions:  I dont have any apparent slack in the prop 

to indicate a loose gear set or too much gear lash.  Might be a little too 

tight going around but not to the point it is grinding metal.  The motor 

mounts are the ones supplied by the Kolb Factory with the 912.  Took the 582 

ones off.    My normal cruise speed for the SS is around 82/85 indicated.  I 

can hit 90/95 in a heartbeat.  Been over a hundred a couple of times at only 

about 5400 rpm.  my set up and aproach is around 70 indicated with touch 

down somewhere around high 40s I think.  at 60 you are still pretty much 

flying although you have a sink rate.  My normal roll out is somewhere 

between 200 to 300 feet, close to take-off roll.  Once the feet are down, 

speed is lost very fast so there is not a lot of roll out.  If I go in slow, 

break it right away, I can stop in about 150 feet without even thinking of a 

nose over.  I love the tall landing legs and forward sweep.  Like I said, if 

it didnt make that awlful noise, I would have the perfect flying machine --  

although it looks a little strange!  When and if the wind and rain stops, I 

will get to work on those great suggestions.  I will let everyone know the 

results for the archieves.  Ted Cowan, Slingshot 912 ul. 	




That sounds like about the same performance envelope as my titan - 95mph cruise, 60mph on final, TD about 40 with full flaps.



Have you tried a different prop type? My next attempt is going to be a powerfin F model which judging by my spare 68" that I have left over from my 2-stroke days, has a very different resonance to the blades than the WD. 

Doubt it'll have the same speed range as the WD but it may run smoother. It's worth a shot anyway especially if it runs smoother.

LS

_________________
LS
Titan II SS

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Mon Apr 13, 2009 8:19 am Post subject: Re: harmonics

Ted,



What kind of brakes did you put on your Slingshot ?  I have the Obrien hydraulic brakes, they are wonderful reliable, I have not had to touch them in over 2 years, they would be perfect on a lighter plane like a firestar, but I just need more stopping power... I could not induce a nose over with the brakes even if I tried.  There have been a couple times with long taxiing on pavement that I have overheated them and had them fade completely.  It really sucks having to shut the engine down on a taxiway to stop.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

mdnanwelch7(at)hotmail.co
Guest

Posted: Mon Apr 13, 2009 9:11 am Post subject: harmonics

>I just need more stopping power... > 

 	  Quote: 	
		   Mike

  
	


   All C 

  

   First C my apologies for the double send of the MIG aluminum reuqest.  Stupid Highesnet choked C and I pushed resend...  ( I miss DSL)

  

   Mike C

  

   Doesn't your brake reservior/master cylinders have options for various mounting holes.  It is likely the O'Brien brakes may not be the problem C just their mounting geometry.

   By moving the top mount closer to the pivot point C you should be able to exert more hydraulic pressure.  Just a thought.....

  

   How about a couple of close-up photos C so we can see what your options are??

  

 Mike Welch

 MkIII



Rediscover Hotmail®: Get quick friend updates right in your inbox.  Check it out.  [quote][b]

Dennis.Kirby(at)kirtland.
Guest

Posted: Mon Apr 13, 2009 9:11 am Post subject: harmonics

"Classification:  UNCLASSIFIED  

 

  

lucien" wrote: << … Fatigue, however, due to the increased thrumming I already know is an issue tho I may eventually get used to that too. >>  

   

Lucien –  

   

Although you’ve heard my story about fatigue failures already, I think it bears repeating, for the benefit of those on this Kolb List who might also benefit.  

   

I experienced a similar harmonic problem in the first year I began flying my Kolb.  I built my plane with a Verner engine (made in the Czech Republic – a 1400cc air cooled, 80 hp, twin cylinder boxer engine).  Like you are experiencing, I too was getting some sort of harmonic whose source I could not identify.  Engine ran smooth, blades tracked exactly, no severe vibration.  But consistently, after every 6 hours of operation, I was discovering BROKEN PROP BOLTS on my post-flight inspection!  Could not pinpoint specifically where the harmonic was originating – was most likely just my particular airframe/engine/prop combination.  I did not want to begin experimenting with different propellers to see if that would solve my problem.  Bottom line for me was, after three times of discovering broken prop bolts, I finally ditched the Verner and bought a used 912 to replace it.   I never discovered what was causing the bolts to break.  But I am happy with my 912 – have not had any reoccurrence of the damaging harmonic.    

   

And so my advice would be:  Don’t ignore those harmonics – you don’t wanna just “get used” to it!  Good for you (and you too, Ted C.), for your tenacious efforts in trying to discover and eliminate the source of your harmonic thrumming!  Eventually, those low-frequency harmonics will take their toll on some part of your airplane which could result is something else failing.  As my experience shows, these things do happen.  

   

Good luck in finding your gremlin(s) …  

   

Dennis Kirby  

Mark-3, 912ul  

New Mexico  

Do not archive  

      

Classification:  UNCLASSIFIED   

 

  [quote][b]

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Mon Apr 13, 2009 9:54 am Post subject: harmonics

The O'Brien brakes do not have sufficient capacity  for a 1,000 lb/100 hp airplane.  They were designed for light ULs.   Not sure what their max capacity is, but it is no where near the max gross of a  MKIII.

  

 Same goes for the MATCO UL brakes with 5/8"  axles.  However, the brakes have a max capacity of 600 lbs.  Little  5/8" ball bearings do not do a good job of carrying heavy loads for long.   Some folks go with dual calipers and get them to stop satisfactorily, but you  are still flying with a wheel that is not strong enough for the  job. 

  

  

 I used 5/8" MATCO's for a long time, then upgraded  to a 3/4" axle with taper roller bearings.  I can't remember the  designation or their max capacity off the top of my head, but it is about 1,000  or 1,200 lbs or more.  Now I have the capability to properly adjust bearing  load, something you can not do with a caged ball bearing.

  

 I usually opt to go a little over the requirement  rather than below it.  Makes my cross country flying much more enjoyable  not to be bothered with preventable problems on the road.

  

 john h

 mkIII

  

  

  

  

  

  

    Doesn't your brake reservior/master cylinders have options for  various mounting holes.  It is likely the O'Brien brakes may not be the  problem, just their mounting geometry.

  By moving the top mount closer  to the pivot point, you should be able to exert more hydraulic pressure.   Just a thought.....

 

  How about a couple of close-up photos,  so we can see what your options are??

 

Mike Welch

MkIII

 

   [quote][b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

mdnanwelch7(at)hotmail.co
Guest

Posted: Mon Apr 13, 2009 10:23 am Post subject: harmonics

John & TNK Co C

  

   If Mike's brakes are not up to the task C does TNK sell a more appropriate C larger axle/wheel/brake C for the heavier MkIIIs and Slingshots?

   Since you went to a larger 3/4" axle C did you opt for a larger/stronger master cylinder?  I didn't see where you mention your present brake master cylinder manufacturer.

  

   I usually go for the "extra heavy duty" version of something C too.  It often proves it was worth it.

  

 Mike Welch

 

  From: jhauck(at)elmore.rr.com

To: kolb-list(at)matronics.com

Subject: Re: Kolb-List: Re: harmonics

Date: Mon C 13 Apr 2009 12:43:37 -0500



  .ExternalClass .EC_hmmessage P {padding-right:0px;padding-left:0px;padding-bottom:0px;padding-top:0px;} .ExternalClass BODY.EC_hmmessage {font-size:10pt;font-family:Verdana;}   The O'Brien brakes do not have sufficient capacity for a 1 C000 lb/100 hp airplane.  They were designed for light ULs.  Not sure what their max capacity is C but it is no where near the max gross of a MKIII.

  

 Same goes for the MATCO UL brakes with 5/8" axles.  However C the brakes have a max capacity of 600 lbs.  Little 5/8" ball bearings do not do a good job of carrying heavy loads for long.  Some folks go with dual calipers and get them to stop satisfactorily C but you are still flying with a wheel that is not strong enough for the job. 

  

  

 I used 5/8" MATCO's for a long time C then upgraded to a 3/4" axle with taper roller bearings.  I can't remember the designation or their max capacity off the top of my head C but it is about 1 C000 or 1 C200 lbs or more.  Now I have the capability to properly adjust bearing load C something you can not do with a caged ball bearing.

  

 I usually opt to go a little over the requirement rather than below it.  Makes my cross country flying much more enjoyable not to be bothered with preventable problems on the road.

  

 john h

 mkIII

  

  

  

  

  

  

    Doesn't your brake reservior/master cylinders have options for various mounting holes.  It is likely the O'Brien brakes may not be the problem C just their mounting geometry.

  By moving the top mount closer to the pivot point C you should be able to exert more hydraulic pressure.  Just a thought.....

 

  How about a couple of close-up photos C so we can see what your options are??

 

Mike Welch

MkIII

 

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John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Mon Apr 13, 2009 11:05 am Post subject: harmonics

I'll bet TNK can supply any part required.   The lighter brake is what comes standard with the kit.

  

 I use the same master cylinder I had with the UL  Matco's.

  

 I stuck with MATCO.  They had what I  wanted.

  

 john h

 MKIII

 [quote]      If Mike's brakes are not up to the    task, does TNK sell a more appropriate, larger axle/wheel/brake, for the    heavier MkIIIs and Slingshots?

  Since you went to a larger 3/4" axle,    did you opt for a larger/stronger master cylinder?  I didn't see    where you mention your present brake master cylinder    manufacturer.

 

 Mike Welch

 

[b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Mon Apr 13, 2009 7:24 pm Post subject: Re: harmonics

 	  Dennis.Kirby(at)kirtland. wrote: 	
		  

Good luck in finding your gremlin(s) â€¦  

   

Dennis Kirby  

Mark-3, 912ul  

New Mexico  

Do not archive  

      

	




FWIW, I did discover this afternoon that the harmonic goes virtually away at cruise. At 100mph the harmonic rrruurrrurrr part is practically gone. 



I now seem to only get it in climb modes of flight, I suppose with the slower airflow through the disk, high AoA of the wing dirties the air up and makes it do its thing.  At cruise, the AoA goes down, airflow is faster through the disk. I guess that's what cleans it up. Shows the prop is not a problem for sure.



BTW, that 100mph cruise is at only 5050 to 5090 rpm and slightly more than half throttle, which is simply spectacular performance. I couldn't get 100mph indicated with the IVO at those rpms no matter how I had it set.

I'm still shocked and amazed even tho I landed a couple hours ago...



LS

_________________
LS
Titan II SS

tc1917(at)bellsouth.net
Guest

Posted: Tue Apr 14, 2009 2:24 am Post subject: harmonics

I do appreciate all the imput on the harmonics.  I check all the bolts and 

as much of the frame and attachments before each flight I can.  I try not to 

miss anything.  I hate to take off and think, darn, I dont think I 

checked --?  I am very aware what vibration can do to objects.  I was a 

truck mech for thirty some years and welder all my life so I know about 

that.  I have MATCO brakes on my slingshot.  Came with manual one handle 

brakes.  Very inadequate.  I did donuts at thirty mph once on landing.  With 

castor wheels you need separate controls.  I bought a MATCO set from Haucks 

bro, had them on a jenny he was building.  Good price.  Good brakes.  Had to 

rig them myself which just required some ingenuity.  Never have had a 

moments problem with them.  Would use them again.  Hope this rain stops so I 

can work on my baby and get some air time.  Got gravity fever.  Glad I aint 

planning on going to sun-un-fun!!!  ted cowan, slingshot, 912ul

tc1917(at)bellsouth.net
Guest

Posted: Sun Apr 26, 2009 2:14 am Post subject: harmonics

Glad to see everyone is back safely from sun-un-fun.  So far this weekend it 

has been interesting.  Have a friend up from Mobile on his way to Florida, 

stopping to pick up a passenger.  They got as far as Eufaula, Alabama and 

lost power.  Seems it has been doing it recently.  After a long two day of 

searching for answers, changing fuel pumps, checking lines, filters, just 

about everything under the sun, I convinced him to pull a carb, (left bank 

went dead on landing).  HKS on a Gull.  We found a piece of rubber inside 

the carb, above the float needle valve, between the barb for the fuel hose. 

It was a big one, about 1/16 of an inch and didnt want to come out.  A flake 

of rubber.  When the power was on it would stop the gas; kicking on the 

elect. pump sometimes knocked it out of the way.  Seen a bunch of stuff 

happen but never an elusive little piece of flat rubber like that.  Kept 

sticking to the wall in there and sometimes you could see it, sometimes not.

Other than that, I finally got to try a new prop on my Slingshot.  Jim 

Holbrook sent me his new one for his 912 installation on his slingshot.  I 

put it on and set it and guess what?  NO HARMONICS!!!  I didnt even have my 

helmet on and it was really quiet.  I put my old one back on and wow, it is 

a noisy piece of crap.  back to the ole woo woo woo.  Tried that piece of 

tape on each blade.  I put it on the worse blade and it changed the tune but 

still noisy.  Put it on all the blades and it was really noisy.  I am going 

to put Jims blade back on this morning and tie it down and wring it out to 

make sure but I am positive I have found the problem.  Now, after all this 

and almost a year and a half of chasing the problem, I hope Warp Drive will 

make good and give me some replacement blades.  If not I will have to take 

them off and spend a lot of money for some other blades, like Kiev.  I just 

had to be able to PROVE what the problem was.  Now I can.  I want to thank 

everyone for all the help.  Take care and happy sailing.  Ted Cowan, 

Alabama, Slingshot 912 UL

NeilsenRM(at)comcast.net
Guest

Posted: Sun Apr 26, 2009 3:25 am Post subject: harmonics

Ted



So what make and size differences are there between your prop and the prop 

Jim lent you that doesn't make noise. Are the prop blades shaped 

differently, are they more or less flexible, also weight?????? Are you going 

to fly with the other prop to check out any performance differences?



Rick Neilsen

Redrive VW powered MKIIIC



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