Today's Message Index:
----------------------
1. 06:07 AM - Update on Jim's Rocket (Jim Stone)
2. 07:23 AM - Re: Update on Jim's Rocket (James Baldwin)
3. 09:46 AM - Re: Update on Jim's Rocket (nico css)
4. 10:43 AM - Jim's Rocket (Steve Irving)
5. 10:50 AM - Re: Update on Jim's Rocket (James Baldwin)
6. 06:22 PM - Re: Update on Jim's Rocket (Jim Stone)
7. 06:36 PM - Re: Jim's Rocket (Jim Stone)
Message 1
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| Subject: | Update on Jim's Rocket |
Rocketteers,
To update you on the rapid battery drain and high CHTs:
I did some starter circuit troubleshooting and found a couple of wire
segments with slightly high resistance and will work on those very soon.
I changed the timing to 20 deg bftdc and yesterday, all temps were
below 390, even in the climb. Leaning still causes #6 to run on up
towards 410 not sure why. Oil pressure adjusted up from 60 to 70 with
two washers. Oil temp still good at 190-200. The #4 cylinder runs
cool, 80 deg or so cooler than the hottest #6, I cleaned the injector
with an ultrasonic cleaner with no improvement. After flying to three
different fields to do a touch and go, and test work at altitude I am
starting to get more confident in the engine and actually did a few
rolls yesterday. I've got about 12 hours now. Following shutdown and a
15-20 minutes simulated fuel stop, I did a restart using the technique
that most guys recommended in the last few days. The trick is to get it
started quickly and with the right technique, that is possible now.
Thanks for all the advice guys.
Jim Stone
Louisville
Message 2
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| Subject: | Re: Update on Jim's Rocket |
Jim -
Has any one spoken to you about or have you read about the whole subject
of injector balance and its relation to an individual cylinder's
EGT/CHT? If not, say so and I'll get you started on an education which
most of the guys with an injection system are beginning to understand is
infinitely tunable. JBB
Jim Stone wrote:
> Rocketteers,
> To update you on the rapid battery drain and high CHTs:
>
> I did some starter circuit troubleshooting and found a couple of wire
> segments with slightly high resistance and will work on those very
> soon. I changed the timing to 20 deg bftdc and yesterday, all temps
> were below 390, even in the climb. Leaning still causes #6 to run on
> up towards 410 not sure why. Oil pressure adjusted up from 60 to 70
> with two washers. Oil temp still good at 190-200. The #4 cylinder
> runs cool, 80 deg or so cooler than the hottest #6, I cleaned the
> injector with an ultrasonic cleaner with no improvement. After flying
> to three different fields to do a touch and go, and test work at
> altitude I am starting to get more confident in the engine and
> actually did a few rolls yesterday. I've got about 12 hours
> now. Following shutdown and a 15-20 minutes simulated fuel stop, I
> did a restart using the technique that most guys recommended in the
> last few days. The trick is to get it started quickly and with the
> right technique, that is possible now. Thanks for all the advice guys.
> Jim Stone
> Louisville
> *
>
>
> *
Message 3
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| Subject: | Update on Jim's Rocket |
Wow, I guess we could all benefit from that, JBB, so would you consider this
"say so" as sufficient motive to go ahead?
-----Original Message-----
From: owner-rocket-list-server@matronics.com
[mailto:owner-rocket-list-server@matronics.com] On Behalf Of James Baldwin
Sent: Thursday, October 04, 2007 7:16 AM
Subject: Re: Rocket-List: Update on Jim's Rocket
Jim -
Has any one spoken to you about or have you read about the whole subject
of injector balance and its relation to an individual cylinder's
EGT/CHT? If not, say so and I'll get you started on an education which
most of the guys with an injection system are beginning to understand is
infinitely tunable. JBB
Jim Stone wrote:
> Rocketteers,
> To update you on the rapid battery drain and high CHTs:
>
> I did some starter circuit troubleshooting and found a couple of wire
> segments with slightly high resistance and will work on those very
> soon. I changed the timing to 20 deg bftdc and yesterday, all temps
> were below 390, even in the climb. Leaning still causes #6 to run on
> up towards 410 not sure why. Oil pressure adjusted up from 60 to 70
> with two washers. Oil temp still good at 190-200. The #4 cylinder
> runs cool, 80 deg or so cooler than the hottest #6, I cleaned the
> injector with an ultrasonic cleaner with no improvement. After flying
> to three different fields to do a touch and go, and test work at
> altitude I am starting to get more confident in the engine and
> actually did a few rolls yesterday. I've got about 12 hours
> now. Following shutdown and a 15-20 minutes simulated fuel stop, I
> did a restart using the technique that most guys recommended in the
> last few days. The trick is to get it started quickly and with the
> right technique, that is possible now. Thanks for all the advice guys.
> Jim Stone
> Louisville
> *
>
>
> *
Message 4
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Jim,
On your #6 cylinder you might want to make a very close inspection of the line
and fittings coming out of the flow divider going to the injector. I had a situation
just like you and after many flights trying to clean the injector, looking
for fod in the flow divider, etc. I discovered the stainless steel line
from the flow divider to the injector had a very small hole in it. Since the fuel
coming out of the flow divider is not under any pressure I didn't have any
of the usual signs of a leak. But the crack was enough to allow air in the system
which caused that injector to be lean. I would swap the line with another
line and see if the problem follows the line. I was able to find the defect in
my line but it took a magnifying glass to do it. The defect was located at the
joint where the end is braised on.
Steve
Message 5
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| Subject: | Re: Update on Jim's Rocket |
Hi Nico,
I will certainly share my knowledge with all the listers and this will
probably start a good general discussion on the subject. Having said
that, my basis of understanding is from my personal experience with
aircraft, my engineering background and, most importantly from people
like GAMI and Barrett Aircraft Engines as they really are the experts
with respect to internal combustion in these very simple normally
aspirated aircraft engines. Anyone who has used a dyno like these
people have are the ones who have documented the behavior we are
observing. I won;t have an rebuilt/new engine on my airplane that
hasn't been on a dyno/test cell.
All of the progress made in the last decade is mostly a result of the
vastly increased amount of digital information available through the
many different data acquisition systems available. Lean of peak
operation was never even considered in my experience before GAMI or with
carburetors. Others began teaching that each cylinder is really an
independent little expansion device all by itself (an internal
combustion engine is nothing more than a device which uses hydrocarbons
to create an expansion in the volume of a fluid which is mechanically
converted to rotational energy, i.e. torque). The inefficiencies were a
result of uneven airflow distribution which led to (AND HERE'S THE BIG
ONE!) each cylinder reaching its peak temperature during leaning
(increased efficiency) at different times. The number (EGT)
wasn't/isn't important, it's WHEN it happens. Who cares if one
cylinder doesn't get as much air as another or if its exhaust tract is
less efficient, it is contributing to the overall output of the engine
at the best level it can given its intake/exhaust tract efficiency with
an ideal amount of fuel for that cylinder. But, if it reaches its peak
of efficiency at a significantly different time than its brother or
sister cylinder then one or more of them will not be as efficient as the
reference cylinder. So, what we do is accept the fact that all are not
equal for whatever reason and match the fuel requirement to the specific
airflow capability of that cylinder. GAMI does this with a matched set
of injectors and Airflow Injection does it by supplying injectors with
different sized orifices in a similar way.
Jim Stone is noting that one cylinder is running at a higher CHT than
another and, all other things being equal, is really suffering from the
probable reality that all of his little engines aren't in lock step
mixture wise. We could take this to extremes by flow matching all of
the individual intake tract/cylinder head/exhaust tracts but the more
practical approach for us is usually to match the peak temp EGT point by
matching the flow nozzle to how much air is really going into each
cylinder. My guess is once he really ascertains his baffling is as
close to perfect as he can get it he will find he needs to log the
temperature peak for each cylinder with respect to overall fuel flow and
then adjust the nozzle for that cylinder until he can standardize it to,
probably somewhere around the .1 to .2 GPH flow rate. I am betting the
CHTs will be close and if not then there are other mechanical issues
(improper cyl/piston clearance, leaky valve seat, ignition issue,etc)
that might be looked at once the cooling airflow is assured. A new
engine during breakin complicates this whole process and should be
completed before embarking on an efficiency quest.
What is really wrong is needing to retard an already retarded ignition
event. The electronic ignitions show us at the higher altitudes the
factory fixed setting of 25 deg BTDC is way late and efficiencies are
easy to get by moving it to somewhere (variable) around 10-12 degress
earlier. Operation lean of peak requires even more time to get the
combustion event completed (or nearly so) with fewer molecules of fuel
to combust. Even at the low speeds we're talking about here (2000-3000
RPM) the ignition/combustion event is in the millisecond range and is
pretty darn quick.
I could say a lot more but this is a pretty basic and well known intro
to the subject and anyone who feels like it can jump in and
add/refute/ridicule or whatever. If the guys from Barrett chime in
you'll hear from the real experts. I haven't asked them a question they
didn't have an excellent answer for based on quite a bit of experience.
GAMI has classes you can attend. JBB
nico css wrote:
>
> Wow, I guess we could all benefit from that, JBB, so would you consider this
> "say so" as sufficient motive to go ahead?
>
>
> -----Original Message-----
> From: owner-rocket-list-server@matronics.com
> [mailto:owner-rocket-list-server@matronics.com] On Behalf Of James Baldwin
> Sent: Thursday, October 04, 2007 7:16 AM
> To: rocket-list@matronics.com
> Subject: Re: Rocket-List: Update on Jim's Rocket
>
>
> Jim -
> Has any one spoken to you about or have you read about the whole subject
> of injector balance and its relation to an individual cylinder's
> EGT/CHT? If not, say so and I'll get you started on an education which
> most of the guys with an injection system are beginning to understand is
> infinitely tunable. JBB
>
> Jim Stone wrote:
>
>> Rocketteers,
>> To update you on the rapid battery drain and high CHTs:
>>
>> I did some starter circuit troubleshooting and found a couple of wire
>> segments with slightly high resistance and will work on those very
>> soon. I changed the timing to 20 deg bftdc and yesterday, all temps
>> were below 390, even in the climb. Leaning still causes #6 to run on
>> up towards 410 not sure why. Oil pressure adjusted up from 60 to 70
>> with two washers. Oil temp still good at 190-200. The #4 cylinder
>> runs cool, 80 deg or so cooler than the hottest #6, I cleaned the
>> injector with an ultrasonic cleaner with no improvement. After flying
>> to three different fields to do a touch and go, and test work at
>> altitude I am starting to get more confident in the engine and
>> actually did a few rolls yesterday. I've got about 12 hours
>> now. Following shutdown and a 15-20 minutes simulated fuel stop, I
>> did a restart using the technique that most guys recommended in the
>> last few days. The trick is to get it started quickly and with the
>> right technique, that is possible now. Thanks for all the advice guys.
>> Jim Stone
>> Louisville
>> *
>>
>>
>> *
>>
>
>
>
Message 6
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| Subject: | Re: Update on Jim's Rocket |
Hi James,
Randy Pflanzer has documented his experience on his website but I have not
yet had a close look at it.
I'll take any help I can get. I'm ready so fire away.
Jim
----- Original Message -----
From: "James Baldwin" <jamesbaldwin@dc.rr.com>
Sent: Thursday, October 04, 2007 10:15 AM
Subject: Re: Rocket-List: Update on Jim's Rocket
>
> Jim -
> Has any one spoken to you about or have you read about the whole subject
> of injector balance and its relation to an individual cylinder's EGT/CHT?
> If not, say so and I'll get you started on an education which most of the
> guys with an injection system are beginning to understand is infinitely
> tunable. JBB
>
> Jim Stone wrote:
>> Rocketteers,
>> To update you on the rapid battery drain and high CHTs:
>> I did some starter circuit troubleshooting and found a couple of wire
>> segments with slightly high resistance and will work on those very soon.
>> I changed the timing to 20 deg bftdc and yesterday, all temps were below
>> 390, even in the climb. Leaning still causes #6 to run on up towards 410
>> not sure why. Oil pressure adjusted up from 60 to 70 with two washers.
>> Oil temp still good at 190-200. The #4 cylinder runs cool, 80 deg or so
>> cooler than the hottest #6, I cleaned the injector with an ultrasonic
>> cleaner with no improvement. After flying to three different fields to
>> do a touch and go, and test work at altitude I am starting to get more
>> confident in the engine and actually did a few rolls yesterday. I've got
>> about 12 hours now. Following shutdown and a 15-20 minutes simulated
>> fuel stop, I did a restart using the technique that most guys
>> recommended in the last few days. The trick is to get it started quickly
>> and with the right technique, that is possible now. Thanks for all the
>> advice guys.
>> Jim Stone
>> Louisville
>> *
>>
>>
>> *
>
>
Message 7
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| Subject: | Re: Jim's Rocket |
Good one Steve,
I'll take a look.
Jim Stone
----- Original Message -----
From: Steve Irving
To: rocket-list@matronics.com
Sent: Thursday, October 04, 2007 1:42 PM
Subject: Rocket-List: Jim's Rocket
Jim,
On your #6 cylinder you might want to make a very close inspection of
the line and fittings coming out of the flow divider going to the
injector. I had a situation just like you and after many flights trying
to clean the injector, looking for fod in the flow divider, etc. I
discovered the stainless steel line from the flow divider to the
injector had a very small hole in it. Since the fuel coming out of the
flow divider is not under any pressure I didn't have any of the usual
signs of a leak. But the crack was enough to allow air in the system
which caused that injector to be lean. I would swap the line with
another line and see if the problem follows the line. I was able to find
the defect in my line but it took a magnifying glass to do it. The
defect was located at the joint where the end is braised on.
Steve
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