X-CGP-ClamAV-Result: CLEAN X-VirusScanner: Niversoft's CGPClamav Helper v1.23.0 (ClamAV engine v0.103.0) From: "William Jepson wrjjrs@gmail.com" Received: from mail-lj1-f174.google.com ([209.85.208.174] verified) by logan.com (CommuniGate Pro SMTP 6.2.14) with ESMTPS id 1321337 for flyrotary@lancaironline.net; Thu, 18 Mar 2021 00:14:57 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.208.174; envelope-from=wrjjrs@gmail.com Received: by mail-lj1-f174.google.com with SMTP id 15so5920099ljj.0 for ; Wed, 17 Mar 2021 21:14:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=fXgbWoGy2zgyOfIYOLRPCZWxZusdCIxcMTIGS9CJluU=; b=HOP3ieDhJXI0rRSouLOkZ/LtIy9IJwuqOaVWBJRIAhMl8TxqXGxNIFQs2ZeoWnjaWY 3ORm0nbwMARd0R32mrGGvBSu8ukgVvZEE7i3i4D9dS/CuzTyd1J01Ysxx87eRgHNG51K uhErrbwptO4CaK2fTwxLvm3NGxm4IaPOgWuns25NR2UkHich9xDsKyz+g+VkFxMSRe0B j0W4BoOGQS6s/p+idPX2Ufk373qdevoHgo1z6mRzTvxuh0EDLZKVtFEmdSqeJ0FH9fFJ vb3pRz0xUFPHVoBIPXshioauP60TQGfdwJPBGVyB9ChAiWL1io1psWiXzRpvJbpe86Pc IMoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=fXgbWoGy2zgyOfIYOLRPCZWxZusdCIxcMTIGS9CJluU=; b=XIcMuOtyZJG4qL/pyZiw89QOwSn3pJip5Kcn82AmeOi88hyKjl/71e1mdt0IOS16l8 sgYuF24HTilT26YijwDLsfgV0WH+DEo4VgxMDCCbMYSBYHQcZObIJbvgAQKzvwrQX3gN Tglb1tTDSLHG7yDGnhTnwgfnaLLODU3bjThowQNUFVSyVBaPCTO4Vbm0iE0AaI8KWXGt FEezJTSQMQ/xwnTFcMg7gKQ5e8J1Pvt0zm+w2DgkU6lXUxjj9tbdNB9NyzNDmdaiRLxY rTRYHd5i3nKmi8CYwmc9Gzv8cVHqZV1L4s0XHEfEc2cbN+15g93pk0n3eQBdEoTakTqo INIg== X-Gm-Message-State: AOAM532PD3SAerNRgd0nDQYIblSzJFXWI0lI0Y/dgCb3XNF6EgluPr8q vqa+orzHXR8UxiIFz8um22u2iR5Toi7JXDKn5qSJ4oSD X-Google-Smtp-Source: ABdhPJxvJhqtONzCkziHrbX0RJgXe+TMiLKOJqfLqiAZnWbpJce06IIgFS5ICVrLuZQrUcndm/CSzBLaS6Su0pQou/o= X-Received: by 2002:a2e:9cce:: with SMTP id g14mr4107713ljj.136.1616040880503; Wed, 17 Mar 2021 21:14:40 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: Date: Wed, 17 Mar 2021 21:14:29 -0700 Message-ID: Subject: Re: [FlyRotary] Re: Balance prop To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary="0000000000009ffdac05bdc7d6d9" --0000000000009ffdac05bdc7d6d9 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Steven, It just so happens that in this weeks kitplanes weekly they were advertising hollow prop mount bolts that can be used on the heavy side for prop ballance. Bill Jepson On Wed, Mar 17, 2021 at 7:31 PM Stephen Izett stephen.izett@gmail.com < flyrotary@lancaironline.net> wrote: > Hi Steve B and Finn > > Appreciate learning from your minds. > I=E2=80=99m trying to understand your process. > I have a new prop and plan to balance engine at ring gear prior to > balancing prop as you are doing. > I=E2=80=99m fortunate to have access to a prop balancer but would like to > understand your process. > > I have some questions: > What device are you using to get your trigger sig from the aluminium tape > reference point? > Should the cro image look sinusoidal, period being equal to rpm and > amplitude proportional to imbalance at the particular angle of rotation > relative to the trigger position? > Should the X and Y signals from the ADLX335 (breakout board mounted on it= s > edge) be the same but 90deg out of phase? > I'm trying to remember my filter theory! Won=E2=80=99t a 100hz filter att= enuate > your signal at 6000rpm by some 3db, so your higher rpm readings may look > better/more balanced than lower rpm readings? > > Steve B. I=E2=80=99m trying to follow your logic. > Having taken 4 readings with a nut moved around the 4 cardinal positions, > if the nut is not way to small or large, and the system was not initially > at best balance, then 2 of the readings (adjacent positions) will show le= ss > amplitude than initial reading, and the other 2 higher amplitude. > > So after the 4 test readings, if the 4 signals are equal and higher > amplitude, wouldn=E2=80=99t this point to the initial balance being bette= r, and so > suggesting a smaller nut be used and retested? Is this what you are sayin= g? > Sorry if I=E2=80=99m confused. > > Could you measure the required angular position of a correction weight > directly from the cro image? That being the angular distance between the > trigger position and the maximum amplitude of the signal minus 180deg? > > Appreciate you guys and the mental stimulation. > > Steve Izett > > > > > On 18 Mar 2021, at 1:23 am, Finn Lassen finn.lassen@verizon.net < > flyrotary@lancaironline.net> wrote: > > > > I'm now on day 5 (newly) trying to balance the engine with prop removed= . > > After a trip chasing a wild goose into the weeds with FFT, I'm now > trying the spreadsheet method: measure amplitude at these four points: > > Unbalanced > > Adding a 7.9g weight (nut) at one of the four bolts (reference) > > Move the nut +90 deg from the reference bolt > > Move the nut -90 deg from the reference bolt > > > > Tried it at 3000 RPM. > > Plugged the numbers into the spreadsheet, it told me to add 28g at 4.5 > deg. Seemed like a lot. The result was a lot worse vibration that I could > actually feel. > > > > Tried again at 4,500 RPM, this time using P-P voltages. > > Now wants me to add 183g at -143 deg. > > > > Very hard to get consistent readings. > > > > Really doesn't make any sense that the addition of a 8g weight > influences the amplitude of the scope curve so little. > > The big washers on each side of the rubber donuts are 30g each. > > > > I'm getting a good trigger signal from a piece of alum tape near rim of > flywheel. > > Using a ADLX335 accelerometer followed by a 100Hz low pass filter and > 300x amp. ADXL335 has sensitivity of 300mV/G. With 300x amp, that's 90V/G= . > > 0.7Vp is about 0.008 Gs or 0.005 ips at 6000 RPM if my math and circuit > is correct. > > V (ips) =3D A (Gs) * 3690 / RPM > > > > Is it possible that the near-sine curve I see on the scope is actually > the reaction (acceleration/de-acceleration of the rotor) to the combustio= n > event? > > > > Steve, how did you balance your engine? > > > > Finn > > > > On 1/28/2021 12:39 AM, Sboese sboese@uwyo.edu wrote: > >> Matt, > >> > >> One cannot balance the prop by placing the balance weights on the > flywheel due to the gear ratio of the psru. I chose to dynamically balan= ce > at the flywheel with the prop removed, then install the prop, and finally > dynamically balance at the prop. That appears to have given good results > for me. > >> > >> Steve Boese > >> > >> > >> > >>> On Jan 27, 2021, at 6:09 PM, Matt Boiteau mattboiteau@gmail.com < > flyrotary@lancaironline.net> wrote: > >>> > >>> =EF=BB=BF > >>> =E2=97=86 This message was sent from a non-UWYO address. Please exerc= ise > caution when clicking links or opening attachments from external sources. > >>> > >>> > >>> How does everyone balance their prop, do they gain access to the > flywheel and add bolts/washers there like a standard aircraft engine? I'm > looking to balance the prop around X60 (Williston, FL), and I forget who, > but someone said we could rent one nearby? > >>> > >>> > >>> Had a 301 ss slip joint bellow for the exhaust and it cracked, which > set me back a few months. The end of my exhaust must have too much > vibration, I will figure out more rubber mounts with the welder to stop t= he > end vibrating. Bought a 2.75" inconel split joint bellow from SPD exhaust > that should handle the heat. > >>> http://www.spdexhaust.com/pdfs/AccPDFs/Bellows.pdf > >>> > >>> > >>> - Matt Boiteau > > > > > > > > > > > > This email has been checked for viruses by Avast antivirus software. > > www.avast.com > > > > > > -- > > Homepage: http://www.flyrotary.com/ > > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > --0000000000009ffdac05bdc7d6d9 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Steven,=C2=A0
It just so happens t= hat in this weeks kitplanes weekly they were advertising hollow prop mount = bolts that can be used on the heavy side for prop ballance.
Bill Jepson=C2=A0

On Wed, Mar 17, 2021 at 7:31 PM Stephen Ize= tt stephen.izett@gmail.com &= lt;flyrotary@lancaironline.n= et> wrote:
Hi Steve B and Finn

Appreciate learning from your minds.
I=E2=80=99m trying to understand your process.
I have a new prop and plan to balance engine at ring gear prior to balancin= g prop as you are doing.
I=E2=80=99m fortunate to have access to a prop balancer but would like to u= nderstand your process.

I have some questions:
What device are you using to get your trigger sig from the aluminium tape r= eference point?
Should the cro image look sinusoidal, period being equal to rpm and amplitu= de proportional to imbalance at the particular angle of rotation relative t= o the trigger position?
Should the X and Y signals from the ADLX335 (breakout board mounted on its = edge) be the same but 90deg out of phase?
I'm trying to remember my filter theory! Won=E2=80=99t a 100hz filter a= ttenuate your signal at 6000rpm by some 3db, so your higher rpm readings ma= y look better/more balanced than lower rpm readings?

Steve B. I=E2=80=99m trying to follow your logic.
Having taken 4 readings with a nut moved around the 4 cardinal positions, i= f the nut is not way to small or large, and the system was not initially at= best balance, then 2 of the readings (adjacent positions) will show less a= mplitude than initial reading, and the other 2 higher amplitude.

So after the 4 test readings, if the 4 signals are equal and higher amplitu= de, wouldn=E2=80=99t this point to the initial balance being better, and so= suggesting a smaller nut be used and retested? Is this what you are saying= ?
Sorry if I=E2=80=99m confused.

Could you measure the required angular position of a correction weight dire= ctly from the cro image? That being the angular distance between the trigge= r position and the maximum amplitude of the signal minus 180deg?

Appreciate you guys and the mental stimulation.

Steve Izett



> On 18 Mar 2021, at 1:23 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironlin= e.net> wrote:
>
> I'm now on day 5 (newly) trying to balance the engine with prop re= moved.
> After a trip chasing a wild goose into the weeds with FFT, I'm now= trying the spreadsheet method: measure amplitude at these four points:
> Unbalanced
> Adding a 7.9g weight (nut) at one of the four bolts (reference)
> Move the nut +90 deg from the reference bolt
> Move the nut -90 deg from the reference bolt
>
> Tried it at 3000 RPM.
> Plugged the numbers into the spreadsheet, it told me to add 28g at 4.5= deg. Seemed like a lot. The result was a lot worse vibration that I could = actually feel.
>
> Tried again at 4,500 RPM, this time using P-P voltages.
> Now wants me to add 183g at -143 deg.
>
> Very hard to get consistent readings.
>
> Really doesn't make any sense that the addition of a 8g weight inf= luences the amplitude of the scope curve so little.
> The big washers on each side of the rubber donuts are 30g each.
>
> I'm getting a good trigger signal from a piece of alum tape near r= im of flywheel.
> Using a ADLX335 accelerometer=C2=A0 followed by a 100Hz low pass filte= r and 300x amp. ADXL335 has sensitivity of 300mV/G. With 300x amp, that'= ;s 90V/G.
> 0.7Vp is about 0.008 Gs or 0.005 ips at 6000 RPM if my math and circui= t is correct.
> V (ips) =3D A (Gs) * 3690 / RPM
>
> Is it possible that the near-sine curve I see on the scope is actually= the reaction (acceleration/de-acceleration of the rotor) to the combustion= event?
>
> Steve,=C2=A0 how did you balance your engine?
>
> Finn
>
> On 1/28/2021 12:39 AM, Sboese sboese@uwyo.edu wrote:
>> Matt,
>>
>> One cannot balance the prop by placing the balance weights on the = flywheel due to the gear ratio of the psru.=C2=A0 I chose to dynamically ba= lance at the flywheel with the prop removed, then install the prop, and fin= ally dynamically balance at the prop.=C2=A0 That appears to have given good= results for me.
>>
>> Steve Boese
>>
>>
>>
>>> On Jan 27, 2021, at 6:09 PM, Matt Boiteau mattboiteau@gmail.com <flyrotary@lancai= ronline.net> wrote:
>>>
>>> =EF=BB=BF
>>> =E2=97=86 This message was sent from a non-UWYO address. Pleas= e exercise caution when clicking links or opening attachments from external= sources.
>>>
>>>
>>> How does everyone balance their prop, do they gain access to t= he flywheel and add bolts/washers there like a standard aircraft engine? I&= #39;m looking to balance the prop around X60 (Williston, FL), and I forget = who, but someone said we could rent one nearby?
>>>
>>>
>>> Had a 301 ss slip joint bellow for the exhaust and it cracked,= which set me back a few months. The end of my exhaust must have too much v= ibration, I will figure out more rubber mounts with the welder to stop the = end vibrating. Bought a 2.75" inconel split joint bellow from SPD exha= ust that should handle the heat.
>>> http://www.spdexhaust.com/pdfs/AccPDF= s/Bellows.pdf
>>>
>>>
>>> - Matt Boiteau
>
>
>
>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0
> This email has been checked for viruses by Avast antivirus software. <= br> > = www.avast.com
>
>
> <Balancing.xls>--
> Homepage:=C2=A0 http://www.flyrotary.com/
> Archive and UnSub:=C2=A0 =C2=A0http:/= /mail.lancaironline.net:81/lists/flyrotary/List.html


--
Homepage:=C2=A0 http://www.flyrotary.com/
Archive and UnSub:=C2=A0 =C2=A0http://mail= .lancaironline.net:81/lists/flyrotary/List.html
--0000000000009ffdac05bdc7d6d9--