Paul,

I have a few nagging questions about Slide Throttles. Will the vacuum
leak on one end of the slide leak evenly between the two intakes? If the
slides are not air tight and are allowed to vacuum leak how do you
prevent dust and grime from galling and binding the slide? While flying
and descending with the throttle closed, will there be extra vacuum on
the slide caused by windmilling of the prop and will this make it
difficult to move your slide? The lack of dynamic balancing and sealing
concerns me.

Luc

I don't know the full answer to that yet. The EGT's were tracking within
about 40 or 50 F but so too was the carb set up. I suspect there is
a problem with the EGT probes we are using. I'll keep my
eye on that. At full throttle the pressure difference is very low
compared to the amount of air going through there so any leakage is minimal.
Most aircraft engines cruise at full throttle at any altitude above
8000 feet.

Dust and grime are taken into stride by the Teflon. Grit tends to embed
itself in the soft Teflon and does not cause sticking problems. It is a good idea
however for the sake of the rotor housing surface to filter
that stuff out.

Windmilling worst case is 15 psi or about 94.248 pounds of force on the
slide throttle. Since the coefficient of friction of Teflon on metal is
about .07 that means worst case force on the slide is 6.59 pounds.
We have no problems opening and closing the slide rapidly.
I checked that before I had the first one made. That is a classic problem
with slide throttles and why they usually have problems with sticking
unless they use ball bearings. It is also the main reason I used Teflon
and not something else. If you want to lower it further you can get
Teflon coated aluminum sheet for the front and back plates. In that
case you have Teflon on Teflon which is a slippery slope indeed :)

Paul Lamar

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