3M Engines

[wgalligan]

Eric,

 I was paying some attention to how much these airplanes vibrate when i was at the Waco contest.  I have been observing many of the same things you have. 2-stroke vs 4-strokes.  The planes with 4-stroke I would pick up while they where running at idle really shake a plane a lot.  Of course the 2 strokes are much happier but still get that thump at lowest idles as you stated.  Something I was comparing was my plane vs others.  I Noticed the aileron thing also and have had to replace the cheap control horns already. Perhaps I should invest in the MK's to eliminate replacement or extend the life of the connectors there.  I have a very stiff fuse.  Made of coremat and c.fiber composite.  The fuse doesn't seem to vibrate a lot back to the tail but the canopy and wings seem to get a pounding but not near as much as other planes I noted over the weekend.   I could move my ailerons to 3/4+ deflection and you can hear the difference in the noise level thats created by the vibrations.  Next up now is changing these servos over to nylon gears.
 I just recieved my 3M and when I get it bench run-in I plan on putting it in this Aries.  Will let you know the difference between that and my O.S.

Wayne


 > There is a time when a 2-c idles so low that it "bounces" as much as a > 4-c at idle. Basically it is missing a beat so that it is firing at the > same frequency as a slow running 4-c. At around 2000-2500 rpm they both > smooth out. 
> 
> I have extensive time on 1.40, and now 1.60, 2-cycles that lets me > compare them with the big YS 4-c's and how they run and shake a plane. I > have run both engine types with and without nose rings. 
> 
> My goal was to get a plane that is shaken and "punished" the least! (Not > ignoring sound issues BTW). I have observed that the best set-up is a > non-nose ring Hydemount. All nose-rings add to airframe vibration. They > provide poor isolation and have to be set with no side pressures to be > iso-effective.
> 
> All my nose ring installations cause aileron-buzz at certain - read most > used in flight - rpm settings. This just kills the digital aileron > servo!  
> 
> The 4-c is the worst culprit by far. The DZ is a shaker and this may be > why the fuel foams and causes dead stick's at low rpms. The L is > smoother but the more nitro you use the more "bang" and thus the more > energy to dissipate. 
> 
> The smoothest set-up, by far, is a 2-c with no-nose ring. There appears > to be no problem with the engine and prop torquing/twisting. The newer > planes have room for a bigger hockey-puck-rear-plate. Planes with FG > cowls are much easier to install without Herculean engineering of a nose > ring support.
> 
> I have put 4 and 2-cycles in the same airframe on the same mounts and > same range of props and I have seen a distinctly better isolation when > the 2-c is installed. The current batch of Webra 1,45, OS 1.40 RX and FI > users can probably tell us what they are seeing.
> 
> The "Mintor-men" will soon be reporting as well - right guys? 
> 
> From a noise point of view my Hydeout with an L, is quieter that my > Temptation with an OS 1.60, that is quieter than my Hydeout with a > DZ.... Not by much however...
> 
> Regards,
> 
> E.
> 
> 
> 
>  
> 
> 

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