Paul

Is a  brass bushing adequate for a throttle sleeve?  I am exploring the
possibility of horizonal 52 mm ID butterfly opening into the 50 mm ID
P-port insert.   To keep the cross sectional area and turbulence to a
minimum I am thinking of using a stainless 2 mm thick disc with  5mm
diameter shafts spot welded on. The short non protruding side shaft stub
is welded on before assembly and the long protruding shaft after
assembly.  8mm OD sleeves are inserted from the outside and the throttle
body is only 12mm thick so it is possible to assembly and TIG weld on
the long side shaft in situ.

This is a study in minimizing  cross sectional area reduction and
turbulence.  Ie no protruding shaft running across the opening but a
thicker plate to retain strength yet allow for  rounding of the leading
and trailing edges for aerodynamic improvement

This is only theory at this point but at WOT with the throttle plate
swinging into the port it might enhance flow  and channel the air as it
is coming into the throttle body after completing a curved path.

Can you model this for me?  Assume throttle unit is a 80mm OD , 52 ID,
12mm thick round tube, with 2mm thick flats milled on each side to
accept the throttle shaft sleeves.  Shaft is on center.  Axially
retaining machine screw positions are 90 degrees apart on  45 degree
radials.  M4 machine screws need a 4.5 mm dia. hole on a 36mm  radius.


Thanks

Doug in Japan

Butterfly? Watch like construction?

The shaft is too wimpy. Too many parts. Too many ball joints.

You will have many hours in this.

You have been living in Japan too long :)

Paul Lamar

Paul

Thanks, that picture will give the shop an idea of what I am looking for.
As for being wimpy, we will see when flow benched.

This is a Bucky Fuller approach (he learned from Henry Ford) where
system components are  purposely minimized to study failure points.
Frankly I think the throttle shaft dia. could be 20% smaller:) The main
stresses are on the bearing shaft junction and the deflection of the
inner plate.  Not shown on the inner plate is the whistle idling hole in
the middle that allows that relieves the disc bending moment and  high
vacuum forces when the throttle is shut.

Two units throttle shafts connect to a throttle cam and coil spring unit
mounted into  the intermediate housing which has to milled anyway. No
need for ball joints if properly made.  Thinner shaft are more flexible
and forgiving in minor misalignment.

But all of this is academic if the slide throttle exhibits stable flow
characteristics at partially closed throttle settings.  Unlike N/A
aircraft over 8,000ft.  I WILL be flying at partly closed throttle
settings. I suspect Dave does as well in his turbo powered RV.  The goal
is to find the throttle with the least turbulence and best flow, and be
mounted as close as possibly to the P ports.

OK I've heard you mutter that last comment many times now.  I am
changing my name:)

Mr. Tsu Rong in Japan