Today's Message Index:
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1. 01:56 PM - Re: CJ Mag #?? (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
2. 02:32 PM - Re: Re: Throttle setting at higher cruising altitudes (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
3. 11:36 PM - Re: Re: Throttle setting at higher cruising altitudes (Jan Mevis)
Message 1
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In the "for what it is worth" category, I have seen a couple of YAKS
(never a CJ) that had the wrong "P" lead on the "wrong" mag. I am
speaking here about is whether #1 is left or is #1 right? Based on that
history, I don't believe anything about which is which. I simply take
an ohm meter and see which "P" lead actually gets grounded when the
cockpit switch is in the position of interest. Just a cautious
suggestion by someone who has gotten bit by an error in this regard more
than once.
Mark Bitterlich
N50YK
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Jim
Sent: Saturday, December 01, 2007 1:13
Subject: Re: Yak-List: CJ Mag #??
Yes, sitting in the Plane it's the right side.
Jim
----- Original Message -----
From: KingCJ6@aol.com
To: yak-list@matronics.com
Sent: Friday, November 30, 2007 8:46 PM
Subject: Yak-List: CJ Mag #??
We have a dead #2 mag and no manual handy. To make sure we work
on the correct mag, # 2 is on the right side as viewed from the cockpit,
correct?
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Message 2
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| Subject: | Re: Throttle setting at higher cruising altitudes |
Walt,
I have no argument about it being highly inadvisable to have full RPM
and throttle set, and then yank the RPM to minimum while leaving the
throttle wide open. I also have no disagreement that when increasing
RPM, the prop control should be increased before the throttle.
The fact is, I don't believe any of this is what was being discussed.
If it was, then I am sorry, because I misunderstood what you were
saying. What I thought you were saying dealt with the inadvisability of
running manifold settings "too high" as compared to a fixed RPM. What I
said was that it is my belief is that you can set the throttle to full,
even at sea level, with the engine RPM reduced. For example, you said:
"There are varying RPM/manifold pressure limits for every engine with a
variable pitch propellor. Probably the easiest (but not recommended)
way to find the first one is to attempt a take-off with the prop control
at low RPM."
For an example of what *I* was talking about: See Yak 50 Operating
Manual: Pre-takeoff Engine Performance Test: "Decrease engine RPM to
70% with propeller control. Increase throttle to wide open. Check
engine instruments." By the way, this is a ground test. As you can see
from this test, the operating manual is telling you to run the engine
with the throttle at maximum manifold pressure with the engine RPM
reduced to 70% with the prop control. Further, it is very difficult to
get any stock M-14 with a standard 2 blade to do much less than 70% RPM
when the throttle is fully wide open. 65% maybe, but 59% is next to
impossible with the models I have flown.
I have no desire to take-off with the RPM reduced to 70%. However, I
often cruise around at sea-level with RPM set anywhere from 75%-85% and
the throttle set WIDE OPEN, and I do not believe I am operating the
engine in such a way as to damage it.
Be that as it may, I support you operating your engine anyway you see
fit.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Walter Lannon
Sent: Friday, November 30, 2007 19:24
Subject: Re: Yak-List: Re: Throttle setting at higher cruising altitudes
Mark;
I guess I am not explaining this properly. There are boost limits with
all engines, including the M14. They are a function of propellor
loading.
I did NOT say that the given cruise settings were the only ones allowed
for cruise. If you wish to burn the gas you may cruise at T/O for 5
mins. or at any setting between T/O and Cruise 1 ( or even lower if you
wish) but you should ensure that you balance the RPM and MP accordingly.
I doubt you would even consider low altitude cruise at full throttle
with the prop control at minimum RPM or attempt a take-off in the same
condition both of which you have stated are perfectly acceptable for
the M14 and I quote "-------there are no " boost limits" to this engine
at ANY RPM"
I refer you to the M14P Maintenance Manual, 072.00.00, Pg. 14, Para.
2.2.2, bottom of page which states "----- do not set the airscrew to
higher pitch before decreasing boost, otherwise the crank mechanism of
the engine may be heavily overloaded. To increase engine rating, first
increase its speed to the desired one (relieve the airscrew) and then
increase boosting." and rest my case.
Walt
----- Original Message -----
From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
<mark.bitterlich@navy.mil>
Sent: Thursday, November 29, 2007 8:48 PM
Subject: RE: Yak-List: Re: Throttle setting at higher cruising altitudes
Point,
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
>
>>I don't have the M14P manual to refer to but Steve has just posted the
> Cruise 1 setting of 64% and 735 mm/hg. This is a recommended limit.
>
> Walt, I am sorry... No it is not a recommended limit. It is
performance
> setting where you should get documented results. It is like a Vx or
Vy
> speed. You climb at those speeds at a given weight, and you should
> obtain a known end. These are not limits. Because the manual
documents
> a Cruise 1 setting and a Cruise 2 setting, that these are the only two
> places that you are allowed to cruise? No Sir. My manual clearly
> states that full throttle is available at ANY RPM SETTING. When I get
> home tonight, I will pull it out and find it and quote it.
>
>>Granted that as altitude increases the throttle must be opened to
> maintain the desired MP. Since these engines have a low blower ratio
> compared to an "altitude" engine the full throttle altitude will be
> reached very quickly.
> In fact it is actually sea level but only with the power settings
given
> in the manual.
> I absolutely agree with Steve's first post to use max. manifold
pressure
> for a given RPM. He has revised it a bit to a given power setting
rather
> than RPM but I think he means the same. The "power setting" is a
> combination of RPM and MP.
> I'm sure you would agree that at sea level a power setting of full
> throttle and 1450 (50%)RPM could be fairly described as over boosted.
>
> I understand that we both understand how manifold pressure works and
are
> not disagreeing over nonsense. But actually no Walt I would not
> consider 55 or 60% RPM (mine simply will not go that low at full
> throttle) with full throttle to be "over-boosted". I honestly do not
> usually run it all the way down to 60% with full throttle, but I do it
> regularly at 70%. I have run for an hour at 1000 feet with 70% RPM
and
> full throttle. Sounds good, runs good.
>
> Consider if you will that some of the big blowers on some of the heavy
> iron birds out there are/were capable of well over 50 inches of
"boost".
> Some of them would go so high that water injection was used. Now we
> have an engine turning 2950 RPM developing a few thousand horsepower
in
> this condition. This was not considered "over-boosted".
>
> Then we have an engine which has a max horsepower of 360 that develops
> around 34 or so inches of manifold pressure at sea level (plus or
minus
> 2 inches or so), and we apply that to an engine turning say 1500 or so
> RPM, and this is suddenly over-boosted simply because it used the same
> manifold pressure at a higher RPM?
>
> Do I feel that there are no limits? Well, certainly there are with
some
> motors, but apparently not with the M-14P because the books that I
have
> read specifically says otherwise.
>
> This is a much better discussion than most lately by the way... It has
> serious bearing on how we all fly.
>
> Mark
>
>
> ----- Original Message -----
> From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
> <mark.bitterlich@navy.mil>
> To: <yak-list@matronics.com>
> Sent: Thursday, November 29, 2007 3:49 PM
> Subject: RE: Yak-List: Re: Throttle setting at higher cruising
altitudes
>
>
> Point,
>> MALS-14 64E" <mark.bitterlich@navy.mil>
>>
>> Really. Well Walt, I am not so sure you are right about that, but I
> am
>> always ready to stand corrected and learn something that I did not
> know
>> before.
>>
>> My M-14 Manual says that you can operate this engine at full throttle
>> with the engine reduced to the very minimum RPM setting available at
> ANY
>> altitude. And ... I've read every available operating manual on this
>> engine that I can find.
>>
>> So what is the limit you are speaking of with the M-14P ???
>>
>> Mark
>>
>>
>> -----Original Message-----
>> From: owner-yak-list-server@matronics.com
>> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Walter
> Lannon
>> Sent: Thursday, November 29, 2007 18:19
>> To: yak-list@matronics.com
>> Subject: Re: Yak-List: Re: Throttle setting at higher cruising
> altitudes
>>
>>
>> Mark Bitterlich wrote;
>>
>>> To the best of my knowledge Steve, there are no "boost limits" to
> this
>>
>>> engine at ANY RPM.
>>>
>>> Mark Bitterlich
>>
>> Mark;
>>
>> There are varying RPM/manifold pressure limits for every engine with
a
>> variable pitch propellor.
>> Probably the easiest (but not recommended) way to find the first one
> is
>> to attempt a take-off with the prop control at low RPM.
>>
>> Walt
>>
Message 3
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| Subject: | Re: Throttle setting at higher cruising altitudes |
Mark and Walt,
Now I am puzzled about the proper procedures. I would be obliged if you and
others could correct me about the following procedure (my fellow Yak 52
owners do this more or less in the same way):
1. before startup, we eventually heat the oil with a small electrical
"spiral" device (the things used for heating water in a cup). I personally
turn the prop AT LEAST 25 blades; prime left and right 4 times, pull the
prop 5 or 6 blades; prime again the cylinders 2 to 3 times; the engine
usually fires after I saw moving three to four blades (three-bladed prop).
2. at startup, the prop control is fully fine (governor control lever
completely to the front),
3. when engine started, I let it run at 42 % (with throttle control very
slowly up until 40 or 42 % is reached, prop all this time full fine) until
the proper temperatures are reached.
4. then I taxi to the holding point, prop still full fine, but reducing the
throttle a lot less than 40 %,just above idle, otherwise my Yak 50 rolls too
fast
5. run-up tests: check first if the engine still has the proper temperatures
(oil above 40 degrees, CHT at 150 degrees); then throttle up to 70 % for the
magneto checks, and then 3 times governor control by pulling back and forth
the prop lever; not too fast, but firmly (with the Extra 300 that I may fly,
the owner asked me to do this prop checks very quickly because they only
have to take away the air bubbles in the governor; he got this advise when
he bought his Extra 300 new from the factory; I suppose this makes sense for
his specific governor mechanism).
6. at take-off, my prop control is full fine, and I SLOWLY advance the
throttle to full power, so having the Yak 50 roll smoothly. I don't push the
stick forward, but keep it in the middle, slightly back, so that the plane
gets airborne from the three wheels at the same time. Then I lower the nose,
gear up, let speed go up; when at 500 feet, I reduce the RPM to 82 % but
leave the throttle full open. In cruise flight, I always have the
prop/throttle settings slightly "oversquare" i.e. 70 % prop, 75 throttle or
60/65.
7. in final approach, I have the prop control at 70 % and use the throttle
(and nose position and trim) to establish the correct speed (145 to 150
km/h, is what I need for a good three-pointer). I aim for the numbers, and
just above the numbers, I have the throttle completely idle.
8. for run-down, I advance the throttle a bit, I put the prop governor again
at fully fine, and the throttle to 65 %, have it scavenge the oil for 25
seconds, then I pull back the throttle to 43 %, shut down the magneto's and
immediately I advance the throttle fully. (in my experience this helps to
avoid big flames at the exhaust pipes; I've seen this on several engines).
Jan Mevis
YK50 RA2005K
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