Message-ID: <012201c44029$b4b0a9d0$f18c1518@rv8>
Reply-To: "kevin lane" <n3773@comcast.net>
From: "kevin lane" <n3773@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-83705@logan.com>
Subject: Re: [FlyRotary] Re: engine mount geometry
Date: Sat, 22 May 2004 11:22:10 -0700
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thanks for the replies, quite valuable.  what I need to figure out now is if
the current mount is salvageable since I have reversed the engine rotation I
originally thought I needed. the rear rubber mounts are about an inch off
center(the wrong way now)  I guess I would end up with short ears and long
ears if I try to use it as is.  with all the triangles it appears that
modification means starting over again.  I'm guessing that when I get way
down the road and try to build exhausts, then the gotcha' will grab me.
looks like it's time to order a redrive so I have something to measure off
of (oww, nice grammar!).  mike, bring your redrive over, I got beer!
Kevin Lane  Portland, OR
e-mail-> n3773@comcast.net
web-> http://home.comcast.net/~n3773
(browse w/ internet explorer)
----- Original Message ----- 
From: <keltro@att.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, May 21, 2004 11:02 PM
Subject: [FlyRotary] Re: engine mount geometry


>   Kevin,
>
>     Ditto the advise from Marv! The Dyke Delta has its offset
>
>   at the firewall end of the engine keeping the prop flange
>
>   on the A/C centerline. FWIW
>
>   Kelly Troyer
>
> --
> Dyke Delta/13B/RD1C/EC2
>
>
>
>
>
>
> > "kevin lane" <n3773@comcast.net> wrote:
> >   > > >
> > I am fabricating the bed mount plate for my 20B in an rv-8.  my
> > understanding, from Tracy's advice, is to offset the engine about 1 1/2
> > degrees to the right if I use his 2.85 drive.  as I see it there is a
> > centerline of the fuselage and a centerline of the engine/redrive.  if I
> > mount them such that they are 1 1/2 degrees out of parallel, then those
> > centerlines will intersect.  my question is where? ...snip...   < < <
> >
> >
> > I'm not an RV builder, but I did have the same decision to make when I
was
> > fabricating the mount for the 13B in my Lancair LNC2.  I temporarily
installed
> > the cowling to the fuselage and found that in its normal position the
> > centerline of the fuselage aligned perfectly with the centerline of the
cowl.
> >  I also noticed that there was a tilt to the flat face that would mate
up with
> > the spinner, so I assumed that the c/l of the prop should match the c/l
of the
> > fuselage, consequently when I built the mount all the offset was at the
rear
> > of the engine.  The center of the prop hub is aligned with the c/l of
the
> > fuselage.  From an aerodynamic standpoint, I don't know that it makes
much
> > difference where the offset comes from, except that if you keep the
firewall
> > end of the engine centered on the firewall, the c/l of the prop will be
offset
> > to the left or right, as required.  This would impact how the cowling
fits up
> > to the fuselage and give you a convex surface on one side and a concave
> > surface on the other where the cowling meets the fuse (when viewed from
above
> > or below).  Personally, I'd prefer to keep the lines of the fuselage
nice and
> > smooth and symmetrical so aligned the prop hub's and fuselage's c/l's.
What
> > happens under the cowling has little impact on the final external
appearance,
> > ergo, I build in the offset back where it would be invisible.  Just my
2c.
> >
> >   <Marv>
> >
> > >>  Homepage:  http://www.flyrotary.com/
> > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html