Today's Message Index:
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1. 08:26 AM - Revised Europa Specifications (Remi Guerner)
2. 08:47 AM - Revised Europa Specifications (Remi Guerner)
3. 09:30 AM - Re: Revised Europa Specifications (rparigor@suffolk.lib.ny.us)
4. 05:30 PM - Re: Revised Europa Specifications (rampil)
5. 06:05 PM - Re: Mod 73 - a safer approach (Brad Shafer)
Message 1
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| Subject: | Revised Europa Specifications |
Thanks Ira for your table. I believe it requires some explanation: what
do the colors mean? Are all figures at full throttle? If not, at least
one parameter (altitude or temperature) is missing.
Can you clarify please?
Remi
I think Rotax is using a sleigh of hand, inconsistently using a moving
target for power output. The engine is advertised as 100 hp, and
only in fine print does one see a 5 min max duration for the rated
power.
Therefore I was using the advertised power rating in my table, which
I enclose below. I can put 75% of max continuous power in fine
print on the table. The table is a simple model, but I find it useful
since
I lack a dyno to test with.
Message 2
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| Subject: | Revised Europa Specifications |
Ira,
I would love to have a mixture control system on my aircraft. However as
I understand how the HACman/Greensky mixture control works, I am afraid
it would unacceptably affect the reliability of the engine.
Up to now, I have not read anything such as reliability analysis,
experience in the field, etc... that would convince me that I am wrong!
Regards
Remi
>>>>>>For fun, here is some of my fight test data from June 2006
demonstrating the lack of altitude compensation of mixture in
the Bing 64 carb.
I keep hoping that someone will report (favorably) on the Greensky
manual mixture control for the 912s>>>>>>>>>>>
Message 3
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| Subject: | Re: Revised Europa Specifications |
Hi Remi
"I'd love to have a mixture control system on my aircraft. However as I
> understand how the HACman/Greensky mixture control works, I am afraid it
> would unacceptably affect the reliability of the engine.
> Up to now, I have not read anything such as reliability analysis,
> experience in the field, etc... that would convince me that I am wrong!"
N4211W not flying yet, but have and will install a mixture control on 914.
First off installed will be a Split Second mixture display that is driven
by a Bosch O2 sensor (will weld a bung on the muffler inlet just
downstream of turbo).
Slight different install on 914 because of Turbo compared to 912/s, but
will use a needle valve to leak pressure from normal airbox pressure side
of enrichment solenoid to manifold cross tube. The more I leak the leaner
the mixture will be.
This will require a run of hose to cockpit then to manifold cross tube, I
will use high temperature Viton tubing.
I will slight richen mixture on main jet and perhaps even jet needle, I
always like to run slight rich when you are making a lot of BTUs such as
100% power or in 914s case War emergency of 115%. It can also cool things
a little on a hot engine (including when stuck on ground).
Then will size a restriction on the controlled "leak" to manifold cross
tube so it will allow me to only lean to ~14.7 at 18K.
Then will have an emergency "rich" button that will allow me to activate
enrichment solenoid that could further richen mixture on less than War
emergency power if I wish. In addition the emergency "rich" button will
completely bypass all my additional plumbing.
For either a 912/S or 914 install, if you at cruise power if you pull
throttle without closing off your controlled leak, your engine is probably
going to quit. On the other hand, if you set mixture at lets say 60% power
and adjust mixture, if you increase power you will go richer than probably
desired.
Another problem is if you lean at altitude, when you come down things will
lean up further.
Having a Split Second display is a nice tool for this control, a EGT
(which I have one on each side of motor) is only semi useful.
HAC has or had a altitude adjusting bellows, I would rather have full
manual control.
I am a motorhead and feel very comfortable fiddling with carburation. If
you can't tune a lawnmower engine to perfection by ear, owned a hot 2
stroke cycle that you managed to run on the edge for long periods without
blowing up, probably not worth considering the controlled 'leak' method of
adjusting Type 64 constant depression carbs.
Ron P.
Message 4
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| Subject: | Re: Revised Europa Specifications |
Hi Remi,
The table is engine performance with a constant speed (AirMaster) prop.
All certificated manufacturers provide a table like mine which shows
the relationship between throttle, selected RPM, and power output.
Rotax does not. The graph is useful to select which combination
works best under specific circumstance, particularly when fuel flow
and TAS are added to the table. My data collection is unfinished for the
bigger version of the table. In this version of just engine, not airframe
performance, density altitude is unneeded. No matter what density
altitude, throttle sets manifold pressure, and obviously without a
turbocharger/supercharger, the maximum MP declines with altitude.
The desired rpm is set on your prop control. Green is the usual
operating range, the other colors are not important here.
Example: 75% power is obtained at 27.5" and 4800 rpm or
26" and 5000 or 24" and 5500 rpm. The "standard" cruise setting
on Continental or Lycomings of 25 squared (or 2500 rpm @ prop at
25" MP) doesn't work out for Rotax because 2500 rpm would be over
6000 engine rpm, but by extrapolation would be over 80% power.
Or, if you set your prop to 5000 rpm for cruise, then you get 75% at
26" (only possible up 4000' DA), and 65% at 23" MAP.
While there are small inaccuracies due my simple model of the Otto
cycle, so far as I know, this table I created is the only published
attempt to provide guidance for 912s drivers with a constant speed
prop.
Cheers,
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=221142#221142
Message 5
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| Subject: | Mod 73 - a safer approach |
It took me awhile but I just finished Mod 73 using Rob's technique and mand
rel. It worked well and without issue (Thanks Rob!). The mandrel is now ava
ilable if someone needs it. I'll cover any US shipping and we'll figure out
the non-US shipping. Just let me know.
Brad Shafer
A251
Chicago, IL
From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-serv
er@matronics.com] On Behalf Of Rob Housman
Sent: Tuesday, March 04, 2008 6:41 PM
Subject: Europa-List: Mod 73 - a safer approach
I'd like to think that I am not the only builder to have found a way to per
manently bond the tailplanes to the torque tubes.
After struggling to forcibly remove the tailplanes (which required both a l
arge pry bar and sufficient heat) after my first attempt at following the f
actory's procedure, I decided that there is a much safer way to do the job.
Substitute a mandrel for the torque tube and do the work on the work benc
h instead on the airplane. The attached drawings show how I did this.
The epoxy still bonded the tailplane to the mandrel, even with plenty of wh
eel bearing grease on the mandrel and frequent rotation of the mandrel whil
e the epoxy cured, but now I had a means to apply force against the rib via
a screw into the outer mandrel section and a closed end tube against the r
ib (not shown in the drawings).
In addition to using the mandrel instead of the torque tube I fabricated an
aluminum retainer rather than rely on the fiberglass-epoxy layup alone to
retain TP06, but this is probably unnecessary.
For anyone who wants to use this method I will provide my (no longer needed
) mandrel assembly at no cost - just pay the shipping charges.
Best regards,
Rob Housman
Irvine, CA
Europa XS Tri-Gear
A070
Airframe complete
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