F3A--Electric.

[Rcmaster199 at aol.com]

With the exception of the output gear which turns at relatively low rpm, the 
remaining parts of the gear box are turning much higher rpm. When it comes to 
transmitted energy, (either sound, electrical or optical),  the higher 
frequencies attenuate first. 

I think Earl alluded to that fact; Troy's statements are ringing true
 also. 
The large majority of the pressure fronts that create the noise
, is created by the prop.

But frankly, I don't understand why there is even an issue in regard to 
electrics. The technology is here, now, and batteries will only get better. Some 
very clever and innovative people have made this a fairly straight forward, plug 
and play technology. My hat's off to the inventors of this stuff

Gary Wright has already been flying the electric 12 lb Funtana for almost two 
years, as I reported in this forum last year, and Jason has simply tapped 
into it early also,  and has given it some serious name recognition. Joe Gross 
also. I would bet dollars to donuts that other World caliber pilots will quickly 
follow Jason's and Gary's lead, engine manufacturer sponsorships 
notwithstanding

I predict that within five years, 50% of  those in our midst will be flying 
electric. As far as cost, I don't believe it will be that prohibitive since the 
LiPol's can give a terrific service life. Consider what 1000 flights costs in 
terms of fuel consumed and the cost of same, for most of us who don't get 
their fuel for free.

There are other reasons that would make me want to make the switch, some of 
which have already been mentioned. Servo life, and general radio and airframe 
life are two keys, as is a cleaner plane aerodynamically. I'm not talking smoke 
and oil goop here

Matt K


> Subj:Re: Re:F3A--Electric. 
> Date:8/9/2003 10:44:07 PM Eastern Daylight Time
> From:<A HREF="mailto:troy_newman at msn.com">troy_newman at msn.com</A>
> Reply-to:<A HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A>
> To:<A HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A>
> Sent from the Internet 
> 
> 
> 
> I don't know for sure about the gear reduction drive....There may be some
> noise from the gear reduction drive yes.....I would bet the majority is
> still from the prop....I listened to the Carerra E setup that Quique has
> flown...To me the noise was from the prop....Now I know the setup that Jason
> is running is different from that in the Carerra E...but my belief is the
> noise we are getting is from the prop.....I just found it very telling
> running different props on the same model...same setup....and same
> RPM....those with tip speeds up near the 400mph mark were the noisy
> ones....if you busted the 400mph mark it busted the 94db(A) mark as well.
> 
> When the tip speeds were down in the 370-380 range the readings on the sound
> meter were significantly lower like in the 90db(A) range...Now remember that
> it is a log scale....so the level of the sound is exponentially higher at
> 93-94 than 90.....
> 
> Personally I think that the gear reduction unit is significant in the noise
> the department but I doubt its the noise (93db) the meter is seeing....Now I
> do understand what Earl has said regarding the frequency...and I would agree
> with it....
> 
> I just see it interesting that I found the main noise contributor on two
> different models as the prop noise.Compared that with other models guys were
> running where the numbers said yep he's too noisy and yep he was on the
> meter just by looking at the rpms and the prop used.......
> 
> Running the number on Jason's hearsay RPM of around 6000, and its a 22" prop
> that tells me the tip speed on the prop is the same as my setup with he
> 17-12 or the 16.5-12W on my 140DZ.....That being the case, its the same tip
> speed, is it coincidence that he is reading the same noise levels as what I
> am getting on my DZ setup?
> 
> Now there is no question in the air I bet he is much quieter....but we are
> not measuring anything that has number associated with it in the air.....its
> all 3 meters away and 30cm off the surface....meter is on the right side of
> the model (which is the opposite side of the YS exhaust header by the way)
> and the mic is pointed right at the model 90deg to the flightpath....So
> basically the meter is pointed right behind the prop....
> 
> I will concede that once you reduce prop noise there is another noise right
> behind it that takes over as the bully in the system and that is most likely
> the exhaust and or Vibration in the airframe.....And this is where as Earl
> stated the Woody was 2db lower consistently.....I think what has happened is
> if we tame the prop noise to say 370-380mph depending on the prop of
> course....the other sounds like vibration resonating in the hollow composite
> fuse and exhaust noise become the key noise makers to reduce next.
> 
> 
> I am curious to play with the electric setup....and see why the noise is
> where it is....But I think its really prop noise...the similar setup on the
> Carerra E,  I have heard in person sounds like a whoosh or a turbine
> sound.......its all prop noise to my un-calibrated ear. There is a whinny
> sound from the gear box but I don't know that this is really the culprit....
> 
> it will be interesting to tell.....the real test would be different gear
> boxes...I think the number I have heard is 6.7 to 1 or something...What
> happens when you change gear ratios and keep the same tip speeds..this would
> require different props for sure....but if the gear box is turning at
> different speeds and the noise meter bumped up or down significantly then I
> could assume it was the gear box...but if the noise stayed the same I would
> think it was still Prop noise....because the prop is still doing its
> 390-400mph thing....
> 
> Just some thoughts....I really no nothing about the electric setup and where
> the noise is coming from....I just thinks its a little ironic that the prop
> tip speeds are the same as my DZ and the noise meter is hitting the same
> values....
> 
> Troy
> 
> ----- Original Message ----- 
> From: "Bjorn Lehnardt" <blehnardt at att.net>
> To: <discussion at nsrca.org>
> Sent: Saturday, August 09, 2003 10:03 PM
> Subject: Re: Re:F3A--Electric.
> 
> 
> > Jason is getting a fair bit of his 93db from the belt reduction drive, no?

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