X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.3 cv=PbaBeRpd c=1 sm=1 tr=0 a=/8lhovTQVRG6fS2jihtHjg==:117 a=x7bEGLp0ZPQA:10 a=A-0mRrAPPO4A:10 a=_RQrkK6FrEwA:10 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=7g1VtSJxAAAA:8 a=l3eIExJTbgvDL0JvvUkA:9 a=nuKQNr3jDtpN4GKH:21 a=bV-XNLFJSrvOt_YW:21 a=c6zgrSap5pV9jhfa:21 a=QEXdDO2ut3YA:10 a=Qa1je4BO31QA:10 a=gvSQh4r-fQ0A:10 a=S0wkRrzPavQA:10 a=jLljAQx8vQdG9QTxYpYA:9 a=zoR1Sn2t7NHbb1FJ:21 a=juH4U19YFT0E7uAL:21 a=0p3I-1UprW0YK43k:21 a=Urk15JJjZg1Xo0ryW_k8:22 a=grOzbf7U_OpcSX4AJOnl:22 From: "Charlie England ceengland7@gmail.com" Received: from mail-io1-f51.google.com ([209.85.166.51] verified) by logan.com (CommuniGate Pro SMTP 6.2.14) with ESMTPS id 558319 for flyrotary@lancaironline.net; Thu, 23 Jul 2020 09:32:28 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.166.51; envelope-from=ceengland7@gmail.com Received: by mail-io1-f51.google.com with SMTP id v8so6239828iox.2 for ; Thu, 23 Jul 2020 06:32:29 -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=3tZob5XW57HvLfbJ15IPHuiy87/Dpfu1J/WNc6L8XdA=; b=uO+oyUUrusODZ3jNOOW/kMhIxYNNPdCezc+bdgN1Rvkq5Utu8qCtAeC5yP6hl0Uw8h lVxOh6QNcjfJIAone6nwR45xcYgyH/gr9gmfLjy96Qf5kRgjGQbl+inrlpEtnh1ewe1C 1LfK0bPVwzPgZdx7ereR9/OMPXf8h1/xVrVmgLmkvOSjl4u/SGc4yyXpVkJtZTF/Vcmb cxXPDrzAVsTIwKHmV57LfSceQxfliUs6trRc0oPJyyDIQsDWJoyD9sI3yclgv3H7eNZG yb7a+N20drFY3664OXHYcE4K/M7JEDdtK5tBTE3T0W779VOVJPCUX2TfNO2GwpK9lbSk plVg== 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=3tZob5XW57HvLfbJ15IPHuiy87/Dpfu1J/WNc6L8XdA=; b=rJJH4VxJmWHnLZubu3vlMCtRBJfCslmEv65HQVoV9fdIagMOTJlWe38pSeppMt+QsA 1pvmJmPQSZWnnc3jn0CRiLLPGBT81/XIa08aLCHxaNLGnsJKKGb4sSj+oU3dcn1zLXKw abk2ZIXgsN2kxxcDikE9F8mfwEMIeikqSDajrOElYG0Xb4Jt/GprzaaAEB8j7hAhB28n ZVVYvJoSY7bKt+w94CuHqIq1mvlh9/CUsdmGTN4jLJCHXEcuPyPW2FNYA+923WMW4J2U fb9Q0EAnTgMijLYOZABdNhTLHIci4AFSLykDmDXFEb+GrLYUGUb+jH1PjEz+R81Y14L9 pGWQ== X-Gm-Message-State: AOAM531E7f2gsXvMy5ncIabLbh0qJZBCLP5jRSaEUn7YxyPHouP5H+W2 mEHeI86+rh8JuQoGiPGK5ml1I0OUZJh8xjnlMGxlMy5T4ks= X-Google-Smtp-Source: ABdhPJyoLD/xKtyFiGE5D4w1iXO+DrliDzdlb0NBUhgcUl9t6t+6NFM5wfJTxG7sgnmSYpyZV+u8RBMCLFzY0SMhYMo= X-Received: by 2002:a02:c903:: with SMTP id t3mr4853682jao.30.1595511130738; Thu, 23 Jul 2020 06:32:10 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: Date: Thu, 23 Jul 2020 08:31:41 -0500 Message-ID: Subject: Re: [FlyRotary] Engine Mount specs To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary="0000000000002ed15105ab1be265" --0000000000002ed15105ab1be265 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, Jul 22, 2020 at 11:23 PM Le Roux Breytenbach breytenbachleroux@gmail.com wrote: > > Hi All members: > The 4130 chromemoly seamless pipe for the engine mount. > What is the appropriate size for building a engine frame, as the included > drawing of Paul L. ( copyright P.L ) > The outside diameter and wall thickness ? > 7/8 Inch OD x 0,069 =E2=80=9C Wall thickness ? > or 0.120 W > > 1 inch x OD ? > Cant find any specifications for such a design. > > > > Sent from my iPhone > Le Roux Breytenbach -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html For perspective, the RVs with up to an IO360 use 3/4" x 0.049" tubing. But as Bobby & Andrew pointed out, crippling is the most critical issue, and all of the RV's tubes that are loaded in compression are much shorter than the bottom-most tube in that pic. I'd be most concerned about that tube; the pair that are arrowed wouldn't concern me that much. Those aren't the only issues; you need to look at the load paths within welded joints, also. The strongest welds are the ones that are stressed along their length. A tension load perpendicular to a weld line is kinda 'worst case'. You obviously want to avoid loading tubes in bending, but there are situations where it *might* be acceptable, or even better. Ex: there are some 'bed mounts' (what that drawing effectively shows) for some Continental 6cyl engines that use a much larger horizontal member (left arrow in the pic), and attach the compression member (bottom most tube in the pic) near the mid point of the horizontal member. This loads the horizontal in bending (requiring upsizing), but shortens the bottom compression member a lot, reducing crippling loads on it. 'Everything is a compromise.' ;-) Be sure that your airframe's 'stock' motor mount doesn't include a horizontal member between the two upper firewall attach points. RVs don't need the tube, but some composite or wood designs might not have the compression strength across the top of the fuselage that's needed to resist those two points trying to come together under positive G loading. Something I *wish* I could have done with my mount is to incorporate a feature found on some radial engine mounts. They often have the 4 firewall attach points being a U shaped bracket bolted through the bottom of the U, to the firewall, and the motor mount termination a vertical tube at each corner. By pulling the bolts on the top & bottom of one side, the entire mount & engine can be swung to one side to service stuff on the firewall or the back side of the engine. Trickier to do with a mount like a taildragger RV, which has the gear leg sockets incorporated in the mount. I was fortunate enough to have two different engineers, both with structural experience, critiquing my design attempts, and one of them is also an excellent welder.... :-) If you can find an engineer or structures guy to look over your shoulder, it would be a good thing. Charlie --0000000000002ed15105ab1be265 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Wed, Jul 22, 2020 at 11:23 PM Le Roux Breytenbac= h breytenbachleroux@gmail.co= m <flyrotary@lancairo= nline.net> wrote:

Hi All members:
The 4130 chromemoly seamless pipe for the engine mount.
What is the appropriate size for building a engine frame, as the included d= rawing of Paul L. ( copyright P.L )
The outside diameter and wall thickness ?
=C2=A07/8=C2=A0 Inch OD x 0,069 =E2=80=9C Wall thickness ?
or 0.120 W

1 inch x OD ?
Cant find any specifications for such a design.



Sent from my iPhone
Le Roux Breytenbach --
Homepage:=C2=A0 http://www.flyrotary.com/
Archive and UnSub:=C2=A0 =C2=A0http://mail= .lancaironline.net:81/lists/flyrotary/List.html

For perspective,= the RVs with up to an IO360 use 3/4" x 0.049" tubing. But as Bob= by & Andrew pointed out, crippling is the most critical issue, and all = of the RV's tubes that are loaded in compression are much shorter than = the bottom-most tube in that pic. I'd be most concerned about that tube= ; the pair that are arrowed wouldn't concern me that much.

Those aren't the only issues; you= need to look at the load paths within welded joints, also. The strongest w= elds are the ones that are stressed along their length. A tension load perp= endicular to a weld line is kinda 'worst case'. You obviously want = to avoid loading tubes in bending, but there are situations where it *might= * be acceptable, or even better. Ex: there are some 'bed mounts' (w= hat that drawing effectively shows) for some Continental 6cyl engines that = use a much=C2=A0larger horizontal member (left arrow in the pic), and attac= h the compression member (bottom most tube in the pic) near the mid point o= f the horizontal member. This loads the horizontal in bending (requiring up= sizing), but shortens the bottom compression member a lot, reducing crippli= ng loads on it. 'Everything is a compromise.' ;-) Be sure that your= airframe's 'stock' motor mount doesn't include a horizonta= l member between the two upper firewall attach points. RVs don't need t= he tube, but some composite or wood designs might not have the compression = strength across the top of the fuselage that's needed=C2=A0 to resist t= hose two points trying to come together under positive G loading.

Something I *wish* I could have=C2= =A0done with my mount is to incorporate a feature found on some radial engi= ne mounts. They often have the 4 firewall attach points being a U shaped br= acket bolted through the bottom of the U, to the firewall, and the motor mo= unt termination a vertical tube at each corner. By pulling the bolts on the= top & bottom of one side, the entire mount & engine can be swung t= o one side to service stuff on the firewall or the back side of the engine. Trickier to do with a mount like a= taildragger RV, which has the gear leg sockets incorporated in the mount.<= /div>

=C2=A0I was fortunate eno= ugh to have two different engineers, both with structural experience, criti= quing my design attempts, and one of them is also an excellent=C2=A0welder.= ... :-)=C2=A0 If you can find an engineer or structures guy to look over yo= ur shoulder, it would be a good thing.

Charlie
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