Today's Message Index:
----------------------
1. 07:54 AM - Re: GT blades for V-530 (psb777)
2. 08:22 AM - Re: Whirl Wind Prop (psb777)
3. 09:43 AM - Re: Re: Whirl Wind Prop (Walter Lannon)
4. 10:57 AM - Re: Whirl Wind Prop (psb777)
Message 1
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| Subject: | Re: GT blades for V-530 |
How much? What diameter is the prop with these blades? More or less than original?
What are the overhaul hours/years on these blades? Are they legal to fit to
EASA (restricted-)CoA certified Yak-18T? Thanks!
--------
Paul Beardsell
HA-YAB http://beardsell.com/flying/ha-yab
Yak-18T http://beardsell.com/flying/yak18t
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329714#329714
Message 2
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| Subject: | Re: Whirl Wind Prop |
This over-square under-square stuff is just short hand for a rule of thumb that
works with some engines and with some systems of units. There is nothing that
says revs should be measured per minute (could be per sec or to be completely
wild, in % of max RPM), and nothing to say manifold pressure should be in inches
of mercury (could be in cm of cider). Always refer to the engine and aircraft
docs. Repeating this under/over square stuff is either patronising or it's
displaying ignorance. Either way, not helpful. As for this prop pushing the engine
stuff and for the car analogies who is to say what is 2nd gear and what
is a hill when it comes to the M14P? The engine manufacturer, again. So also not
helpful. That the M14P %RPM figure and cmHg figures are similar in some engine
running regimes is nothing but a happy accident of units.
--------
Paul Beardsell
HA-YAB http://beardsell.com/flying/ha-yab
Yak-18T http://beardsell.com/flying/yak18t
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329717#329717
Message 3
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| Subject: | Re: Whirl Wind Prop |
Agreed, every aircraft engine should be operated in accordance with the
manufacturers instructions. No question about that.
However, it appears you are suggesting that it is not helpful to understand
the reasons for those instructions.
In this community there are many new owners who have never operated a radial
engine, possibly never a variable pitch propellor or have any experience
with a supercharged aircraft engine.
Most want to understand how these things work.
BTW: It is mm/Hg not cm.
Walt
----- Original Message -----
From: "psb777" <matronics.com@beardsell.com>
Sent: Saturday, February 05, 2011 8:19 AM
Subject: Yak-List: Re: Whirl Wind Prop
>
> This over-square under-square stuff is just short hand for a rule of thumb
> that works with some engines and with some systems of units. There is
> nothing that says revs should be measured per minute (could be per sec or
> to be completely wild, in % of max RPM), and nothing to say manifold
> pressure should be in inches of mercury (could be in cm of cider). Always
> refer to the engine and aircraft docs. Repeating this under/over square
> stuff is either patronising or it's displaying ignorance. Either way, not
> helpful. As for this prop pushing the engine stuff and for the car
> analogies who is to say what is 2nd gear and what is a hill when it comes
> to the M14P? The engine manufacturer, again. So also not helpful. That the
> M14P %RPM figure and cmHg figures are similar in some engine running
> regimes is nothing but a happy accident of units.
>
> --------
> Paul Beardsell
> HA-YAB http://beardsell.com/flying/ha-yab
> Yak-18T http://beardsell.com/flying/yak18t
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=329717#329717
>
>
>
Message 4
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| Subject: | Re: Whirl Wind Prop |
I am unsure which of us trying to teach the other's grandmother to suck eggs. Whatever
the unit is it is not mm/Hg. It would be mmHg. That or cmHg. And this
refers to the height of the column in a mercury barometer. Hg is the chemical
symbol for mercury. The height is either 760mm (millimetres) Hg or 76cm (centimetres)
Hg at standard sea level atmospheric pressure. If you think it convenient
to have to have a number closer to the %RPM of your engine then it is the
cmHg figure you want. The manifold pressure gauge in my and other Yaks I've seen
is calibrated in neither of those units, they are calibrated in dm (decimeters)
Hg. The engine manual too: Cruise 1 is 64% engine speed at 7.35 dmHg (or
cmHg/10).
As for the Morris Minor put-putting up a hill in top gear full throttle, as long
as the term under or over square is not used, I'm happy.
--------
Paul Beardsell
HA-YAB http://beardsell.com/flying/ha-yab
Yak-18T http://beardsell.com/flying/yak18t
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329753#329753
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