> Paul,
>
> Nothing wrong with your idea, but who is going to make that for
> you? You have to pay someone to machine the needle and other
> parts. It's easier -- and maybe cheaper -- to just buy a valve
> off the shelf. Parker is part of Parker Hannifin which makes a
> lot of aircraft parts, so getting one is easy. (I don't think
> think this valve is meant for aircraft use though, but it is
> high quality.)
>
> http://www.parker.com/ead/cm2.asp?cmid=3092
>
> Regards,
>
> Gordon.
>
> Yes but nothing I have seen off the shelf so far is near
> as workable as this design. The cost is cheap. I'll front
> a bunch of SS needles made on an NC lath. Cost probably
> less than $5 each. Or people with lathes can make them
> themselves.
>
> The rest of it is made from SS tube and SS 37 degree flare 1/8th
> JIC fittings.
>
> There are no pivots or levers to add backlash or slop.
>
> Paul Lamar ...No rotor no motor.
>
> Paul,
>
> There is no slop or levers with the extension rod either. You just
> have a knob you turn for leaning. The Parker valve even has a panel
> nut -- you just drill a hole in the firewall, take off the knob
> and attach the valve to the firewall with the panel nut. Run the
> extension to the instrument panel and reattach the knob there. Done.
>
> How would you seal your needle valve? You have to have some way
> to keep fuel under pressure from squirting out the needle tube.
> Look at the drawing of the Parker valve -- it uses a packing
> gland, a packing washer and PTFE packing to accomplish the
> sealing. It would cost more than $5 to replicate all that from
scratch.
>
> Regards,
>
> Gordon.
-----------------------
> O rings.
> Paul Lamar
------------------------
Paul,
The moving valve could be made of larger diameter rod. On one side a
tapered flat 3 inches long could be ground such that the deepest end
of the flat would be towards the fire wall. (This can be made by
holding a brass rod in a steel vice at a slight angle to the
horizontal and using a hand held angle grinder, gently touching the
vice jaws) The tapered flat would work through the orifice. Pushing
the valve spindle in from the panel would then increase fuel flow.
Is an orifice needed? Fuel entering from the side of the tube would
be cut off by the valve rod, and only flow when the flat is in an
appropriate position. This is back to your original design of
tapered slot on the slide throttle. Colin Smith
----------------------------
I'll have to think about this for awhile. Can you work up
a sketch?
----------------------------------
Never mind about the sketch. I got the picture. Here is a slight
variation. No need to worry if the needle rotates
which would be the case if a flat was machined on it.
The needle is a slip fit inside the .5" OD .43" ID tube.
Fuel comes in at the top and goes out the bottom.
Works the right way. Saves about 2 inches in over all
length. The triple O ring end is drilled and taped
for the 10-32 leaning cable end. Only a slight taper
need be machined in the needle as the fuel goes around
both sides and down to the output port. The tube is about
.43 ID so the 10-32 jam nut will fit inside.
When the needle's left O ring is between ports and the needle
is all the way to the right fuel is totally
cut off. Once the left O-ring moves past the output
port fuel starts to flow. This is kind of a combination
barrel valve and needle valve.
This design has another subtle advantage. If the leaning knob
is suddenly pushed in an extra shot of fuel, stored
in the needle valve, will be forced into the intake
which is just what is needed when an engine is accelerated.
Paul Lamar ...No rotor no motor.
Paul,
Good. Seems to solve the problem.
Colin Smith
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