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2nd Kelly's opinion. the info I have said type 2 was for engines
with *extended hub* constant speed prop (~2 1/2" beyond a normal
constant speed), which moves the cg forward a lot. Van's no longer
even supplies type 2 mounts because they are so rare.
IMO, the only reason to do dynafocal at all is because the mounts
are so common. the old 'conical' style mount (4 parallel bolts)
would be just fine for a rotary with its inherently smooth
operation. The reason Lyc did the dynafocal was an attempt to damp
their flat 4's horrendous vibration pattern (not that effective...).
The conical mount Lyc motors can be converted to dynafocal by an
engine shop, implying that the bolt circle is virtually identical.
The downside to dynafocal is that the rubbers cost about a factor of
10-15 more money than conical mount rubbers. Less than $30 for a set
of conical; $300-$500 for dynafocal.
I still have available the dyna ring off my original RV motor mount,
if there's a scanning shop in Jackson MS. If you can find a shop,
let me know & I'll take it there for a scan.
To address the concern about attachment strength: with a new
housing, it should be relatively simple to add a piece to grab the
top of the middle iron or even the bellhousing flange top bolts if
you're really paranoid. I'm no engineer, but I'd think that there is
plenty of bolt & aluminum area to take the shear loads; the only
question in my mind would be the bolts at the top that will be in
tension in the cast iron casting. I have a hard time believing that
6 gs could stretch the 4 or 5 bolts across the top of the 'stack'
enough to affect the engine, at the relatively low power levels that
will be used in a/c. (I'm strictly talking about 2 rotor engines,
not the 3+ rotor versions.)
Charlie
On 4/26/2011 9:04 AM, Kelly Troyer wrote:
Jarrett,
The "Mistral" 13B engine (and their 20B) CG of 9.44
and 11.73 inches respectively was complete with
all accessories and redrive (which is heavier than
Tracy's RD1X re-drives of 44 lbs)................The addition
of a constant speed (with normal extension) would still
keep the Type 1, 30 degree focal point of 14.373"
in front of the 13B CG (IMHO)...........The 20B CG with
normal constant speed would have to be calculated
to see if it remained within the Type 1, 30 degree 14.373"
focal point..............The type 2,18 degree seems
to have been used only on a specific 0-320 model installed
in the twin Comanche (That does not keep your
Lancair from having this engine
installed)..................
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: H
& J Johnson <hjjohnson@sasktel.net>
To: Rotary
motors in aircraft <flyrotary@lancaironline.net>
Sent: Tue,
April 26, 2011 2:36:54 AM
Subject:
[FlyRotary] Re: Mistral 'Like' Intake
Interesting. I may very well be wrong but for some
reason I had it in my head [once it was jared by Bills
mention of Type 2] that the Type 2's were usually used for
engines w/ constant speed [due to weight] and the type 1's
were used mainly for fixed pitch. [old wives tale?] I
would think that due to our extra weight out front on the
nose a Type 2 would be more in order. Having said that, I
have no idea where the CofG on a 13B is located and how
that relates to the various focal points. In addition, how
adding a PSRU on the nose would impact the CofG [and or a
electricl pitch prop etc]. I'll have to do some reading
and see what I can dig up. Certainly a good place to
start w/ as far as a ground up design on the mounting
housing.
Lynn, re: Strength of the Connection.
I remember you stating some of those points a while
back. I'm wondering if, in our lower power state, these
are as much a concern as they are in the racing world?
It would certainly be possible to add extra parts to the
install [the thickened bottom plate, or perhaps some
form of a stiffener that locks the block from torque
related movement front to back { all just thoughts
flashing through my brain, RHRN}. I've not heard comment
about how Mistral addressed this [or if it was a concern
of theirs?].
Kelly, do you know of any additional connection points
[dowels or pins etc] that were needed for the instal of
a Mistral housing?
It certainly is not my first 'pick' to have a mounting
housing which needs modifications to a short block, to
allow it to be installed.
Jarrett Johnson
www.innovention-tech.com
Jarrett and Bill,
Here is the source of my "Dynafocal" mount
info...............
Kelly Troyer
"DYKE DELTA
JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: Kelly
Troyer <keltro@att.net>
To: Rotary
motors in aircraft
<flyrotary@lancaironline.net>
Sent: Mon,
April 25, 2011 10:37:25 PM
Subject:
[FlyRotary] Re: Mistral 'Like' Intake
Bill,
My info says the Type 2 ,18 degree was
introduced when O-320's were put in twin Comanches
with extra long constant speed prop extensions
(for a more streamlined cowl)............This then
put
the engine CG further forward so to keep the
Dynafocal mount "Focal" point slightly ahead of
the
engine CG the Dynafocal mount angle was reduced
from 30 degrees to 18 degrees.........
The Dynafocal type 1 focal point is
14.323 inches from the mounts..................The
"Mistral" 13B
engine CG is 9.44 inches from the mount so
should work well with the type 1, 30
degree Dynafocal
mount..............IMHO
Kelly Troyer
"DYKE
DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From:
Bill Bradburry
<bbradburry@bellsouth.net>
To:
Rotary motors in aircraft
<flyrotary@lancaironline.net>
Sent:
Mon, April 25, 2011 10:13:02 PM
Subject:
[FlyRotary] Re: Mistral 'Like' Intake
There is also a Type 2
Dynafocal that I think is in more common
usage. If I recall the angle on it is
17 degrees.
Bill B
From: Rotary
motors in aircraft
[mailto:flyrotary@lancaironline.net] On Behalf Of Kelly
Troyer
Sent:
Monday, April 25, 2011 4:57 PM
To:
Rotary motors in aircraft
Subject:
[FlyRotary] Re: Mistral 'Like' Intake
I
found the "Dynafocal"
info................Was on my
other computer
!!..................
Kelly Troyer
"DYKE DELTA
JD2" (Eventually)
"13B ROTARY"_
Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50
Turbo
From: H & J
Johnson
<hjjohnson@sasktel.net>
To:
Rotary motors in aircraft
<flyrotary@lancaironline.net>
Sent:
Mon, April 25, 2011 11:21:48 AM
Subject:
[FlyRotary] Re: Mistral 'Like'
Intake
The
scanning should give in the tens
of thousands [0.01"] or less
depending on what type of
equipement used etc. That in
conjunction w/ bolt hold
placement that I already have
[lots of collected data over the
years] I should be able to
duplicate the basic geometry.
From there it will become a new
product in that we want to make
it something that works for
everyone [or as many as
possible] to make it a viable
unit. That info, mixed w/
knowing what the 'Standard'
mount geometry is should get us
where we need to go.
Best
regards
Jarrett Johnson
www.innovention-tech.com
-----
Original Message -----
From:
Kelly Troyer <keltro@att.net>
Date:
Monday, April 25, 2011 10:03 am
Subject:
[FlyRotary] Re: Mistral 'Like'
Intake
>
Jarrett,
>
> I do not know
exactly what dimensions the
scanning give you
> such as bolt
> hole placement,
etc.........I presumed
> that the angles of the
mount ears needed for the
"Dynafoal" mounts
> would be
> "Dead" on though..........
>
>
> Kelly Troyer
> "DYKE DELTA JD2"
(Eventually)
> "13B ROTARY"_ Engine
> "RWS"_RD1C/EC2/EM2
> "MISTRAL"_Backplate/Oil
Manifold
> "TURBONETICS"_TO4E50 Turbo
>
>
>
>
>
________________________________
> From: H & J Johnson
<hjjohnson@sasktel.net>
> To: Rotary motors in
aircraft
<flyrotary@lancaironline.net>
> Sent: Mon, April 25, 2011
10:49:43 AM
> Subject: [FlyRotary] Re:
Mistral 'Like' Intake
>
> Excellent, now I just need
to get some Dynafocal dimensions
[I've
> seen it on
> the web in the past, just
gotta re-locate the dimensional
> 'standards']. That in
> conjunction w/ a few scans
& the picture will start to
really take
> shape!
>
> I love progress :)
> I can't say Thanks enough
Kelly, w/out the help of
yourself and
> others it would
> be a much steeper curve to
get it up to speed.
>
> Jarrett Johnson
> www.innovention-tech.com
> -- Homepage:
http://www.flyrotary.com/
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>
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>
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