Today's Message Index:
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1. 03:18 AM - Re: Prop won't slow below 70% (Craig Payne)
2. 07:14 AM - Re: Re: Prop won't slow below 70% (Richard Kelley)
3. 10:59 AM - Re: Re: Prop won't slow below 70% (Walter Lannon)
4. 12:00 PM - Re: Re: Prop won't slow below 70% (Walter Lannon)
5. 09:43 PM - Re: Prop won't slow below 70% (glipaz)
Message 1
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| Subject: | Re: Prop won't slow below 70% |
I have seen differences in " dome pistons" used in V530 hubs (and Chinese).
The main thing to check is the amount of angular motion allowed by the
assembly. There is a "ring" on the base of the piston that is held in place
with cotter pins. The Thickness of that ring controls the amount of linear
piston movement, hence total angular movement in the blades. Also check
depth of the dome being used.
I have seen different ring thicknesses and by mixing Chinese and Russian
parts in my Yak-Chang or Nan-Yak, I could get 2900 RPM fine pitch and as
low as 1680 RPM at low MAP settings in coarse pitch. Once managed 520 NM on
46 gallons. With an aux tank of course!
Craig Payne
Message 2
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| Subject: | Re: Prop won't slow below 70% |
Dont know that one. 210-787-0327
Sent from my iPhone
> On Apr 21, 2019, at 3:17 AM, Craig Payne <yakman285@gmail.com> wrote:
>
> I have seen differences in " dome pistons" used in V530 hubs (and Chinese). The
main thing to check is the amount of angular motion allowed by the assembly.
There is a "ring" on the base of the piston that is held in place with cotter
pins. The Thickness of that ring controls the amount of linear piston movement,
hence total angular movement in the blades. Also check depth of the dome being
used.
>
> I have seen different ring thicknesses and by mixing Chinese and Russian parts
in my Yak-Chang or Nan-Yak, I could get 2900 RPM fine pitch and as low as 1680
RPM at low MAP settings in coarse pitch. Once managed 520 NM on 46 gallons.
With an aux tank of course!
>
> Craig Payne
Message 3
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| Subject: | Re: Prop won't slow below 70% |
Hi Gill;
If you were removing the prop. the first operation would remove the skull
cap then the safety wire, screw and lock plate that keeps the pitch change
cylinder in place on the hub.
Rotate and remove the cylinder complete with the piston from the hub.
Remove the piston from the cylinder for inspection.
This assembly is absolutely identical and interchangeable whether Chinese,
Russian or Polish with one important difference.
Looking at the piston you will see there is a ring on the fwd. side that is
held in place by 2 cotter pins. This is the coarse pitch stop ring that
contacts the inner fwd. surface of the cylinder and determines the coarse
pitch blade angle and therefor the pitch range of the prop. This is
adjustable by varying the ring thickness.
If the ring thickness is approx. 4 mm (5/32") it is Russian for a coarse
blade angle of approx. 35 deg. If approx. 8 mm it is Chinese (or Polish)
for a coarse angle of approx. 31 deg.
Let me know what you find,
Walt
-----Original Message-----
From: glipaz
Sent: Saturday, April 20, 2019 8:24 PM
Subject: Yak-List: Re: Prop won't slow below 70%
Hi Walt. Pitching forward causes RPM to increase.
Re pitch change piston, I assume you mean the piston in the hub. I bought
it with the hub and assume it is standard Russian.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488837#488837
---
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Message 4
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| Subject: | Re: Prop won't slow below 70% |
Gill;
In describing the piston/cylinder function I should have written "---------
and determines the maximum coarse pitch blade angle ---------".
Walt
-----Original Message-----
From: Walter Lannon
Sent: Sunday, April 21, 2019 10:59 AM
Subject: Re: Yak-List: Re: Prop won't slow below 70%
Hi Gill;
If you were removing the prop. the first operation would remove the skull
cap then the safety wire, screw and lock plate that keeps the pitch change
cylinder in place on the hub.
Rotate and remove the cylinder complete with the piston from the hub.
Remove the piston from the cylinder for inspection.
This assembly is absolutely identical and interchangeable whether Chinese,
Russian or Polish with one important difference.
Looking at the piston you will see there is a ring on the fwd. side that is
held in place by 2 cotter pins. This is the coarse pitch stop ring that
contacts the inner fwd. surface of the cylinder and determines the coarse
pitch blade angle and therefor the pitch range of the prop. This is
adjustable by varying the ring thickness.
If the ring thickness is approx. 4 mm (5/32") it is Russian for a coarse
blade angle of approx. 35 deg. If approx. 8 mm it is Chinese (or Polish)
for a coarse angle of approx. 31 deg.
Let me know what you find,
Walt
-----Original Message-----
From: glipaz
Sent: Saturday, April 20, 2019 8:24 PM
Subject: Yak-List: Re: Prop won't slow below 70%
Hi Walt. Pitching forward causes RPM to increase.
Re pitch change piston, I assume you mean the piston in the hub. I bought
it with the hub and assume it is standard Russian.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488837#488837
---
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https://www.avast.com/antivirus
Message 5
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| Subject: | Re: Prop won't slow below 70% |
Walt, thank you. I had not heard/known about this difference in piston ring size
and will look to see. If I open it and find that the ring is the Chinese 8mm
size, can I replace it or mill it down to 4mm or do I need a replacement piston?
I assume the cylinder does not need to be replaced.
Gil
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488854#488854
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