>> Hi Paul,
>> I was wandering how the slide throttle PP engine turned out? Since
>> the stock turbo turned out to be a big bust, I have removed it
and my >> plane still flies, >> but I'm considering building a PP
one. Please put me back on your >> list. Still don't know how I
dropped out in a first place? You were >> missing at this year's
Shady Bend Roundup? >> Bulent "Buly" Aliev >> FXE Ft Lauderdale,
FL >> http://tinyurl.com/dcy36 >> >> Well due to my own
stupidity I bought some expensive high temperature >> epoxy to bond
the p-ports tubes in and it was a disaster. >> It did not bond to
the aluminum and we had a pin hole leak. >> It did not show up
until after we ran it on the dyno and >> shipped it to Mark. When
Mark ran the engine he found water >> in the combustion chamber and
he took it apart shipped >> some of the parts back. We had first
thought that it >> froze the block being in the unheated hangar at
20 below. >> Right around that time Dave Leonard had froze his
engine >> leaving it outside at 30 below at Mammoth Mountain
airport >> while skiing without the proper antifreeze mix. He made
>> an excellent off airport landing on the freeway and Robin, >> I
and a dozen others helped him take the wings off and >> truck it
back to LA. I digress. >> >> We found out the epoxy was not mixed
correctly on one side >> of the rotor housings and that was causing
the problem. We "fixed" >> it with JB Weld and Mark put it back
together and tried it again. >> Better but not perfect. What I
should have done was pressurize >> the cooling system to 30 psi
without the e-shaft and rotors in >> the engine to check for
cooling system leaks BEFORE final >> assembly. Hind sight. >> >>
Mark and I met in the middle of Utah and I took the engine >> back
to LA see if I could fix it without taking it apart. >> After some
experimentation I was not comfortable doing that >> so Mazdtrix
took it apart again. I then chiseled out the high buck, >> high
temperature, hard as a rock epoxy from the other side of >> the
rotor housings and sure enough it had not bonded to the >>
aluminum. JB Weld bonds 1000 times better. I replaced it >> with JB
Weld and I am now confident we found the problem. >> >> Mark, to
his great credit persevered through it all and >> the engine is now
being put back together and will be pressure >> tested BEFORE it is
shipped back to Mark this week or next. >> >> Thank you Mark for
putting up with all this. I owe you. >> >> When Mark gets it
running again I will fly out and help >> him tune it. When we ran
it on the dyno we had trouble >> tuning it with Tracy's EFI because
the dyno load is >> so much different than prop load. It was
costing me $650 >> a day on the dyno fooling around so we did a
quick and dirty >> install of Weber 51 mm carb and got about 240 HP
at 6500 RPM >> right off the bat. The Mazdatrix guys were so sharp
tuning >> the Weber it took only one jet change and we were well within
>> the power ball park.
>>
>> Anyway check out the latest hot tip very simple low pressure
>> mechanical fuel injection on the web site.
>> http://www.rotaryeng.net/mech-fuel.html
>>
>>
>> Paul Lamar ...No rotor no motor.
>
> Thanks Paul,
> Very impressive performance from the engine on the first run.
I'll > start collecting the components for a PP port one. > The
low pressure system looks interesting, bit it is still an idea. >
It can get scary up there while experimenting :). > Buly > > True
but there are half a dozen low pressure fuel injection > slide
bodies on the the market very similar to this. The Ellison > is
widely used. It is very very simple and cheap. They all work >
pretty much the same. > > Geir's idea of using both is a good one
and easy to do. Klaus has > already done that. Used an Ellison and
EFI. Klaus is also flying > a Teflon slide throttle on his O-200
currently with EFI. See the > 3D jpg. > > If you have a low
pressure pump in your system already you are > 25% there. > >
http://www.sonex-ltd.com/Sonex_35_Hamburger.html >
http://www.ellison-tbi.com/ >
http://www.aeroconversions.com/carb_saying.html
> http://www.vansairforce.com/community/showthread.php?p=38120
>
http://www.revmasteraviation.com/products/revflow_injector_carburetor/index.h
tm
>
>
> The big advantage to our system is there are two $11 leaning valves.
> One for each rotor. Tony on here is going to try two $350 Ellison's.
> Tony is bucks up :)
>
> Paul Lamar ...No rotor no motor.
$350? Take a look at www.ellison-fluid-systems.com/order_form.htm
<http://www.ellison-fluid-systems.com/order_form.htm>.
The least expensive item listed is $825! The EFS-5 for a 240 HP 13B
PP is listed at $1,759! Maybe the street price is different?
Some flames too. They admit it is sensitive to vapor: from Ellisons FAQ:
"A diaphragm controlled fuel metering device such as the Ellison
Throttle Body Injector ("TBI") .... is more susceptible to
operational difficulties due to vapor formation than a conventional float
carburetor." And "a bubble of vapor or air in the fuel line will
cause a momentary power loss." Momentary? Can you say "spin"?
See NTSB report SEA04LA062
www.ntsb.gov/ntsb/brief2.asp?ev_id=20040405X00421&ntsbno=SEA04LA062&akey=1
<http://www.ntsb.gov/ntsb/brief2.asp?
ev_id=20040405X00421&ntsbno=SEA04LA062&akey=1>
This report does not accuse the TBI as the cause. There was no evidence
of a physiological or mechanical problem. I note, however, that a
fuel vapor problem would not be in evidence after the wreckage had
time to cool. Another pilot witnessed the fatal accident; his
statement is in the report.
One way to avoid vapor problems is to use a high pressure fuel line.
This, of course, has its own risks. Another way is to design the fuel
delivery system for anti-vapor characteristics at the beginning. Easier
said than done. Ellison discusses some on their web site. A fundamental
problem with low pressure systems is that at high altitudes the
temperature at which vapor generation becomes a problem gets lower
and lower while the fuel flow in the lines gets less and less. Under
the cowl the temperatures can be quite toasty even when the OAT is -20.
Insulation helps, but the fuel has to carry away the heat unless
sufficient cool air is present. Of course, high altitude means that the
pilot has a chance at recovery. More dangerous is the "momentary
power loss" right after take off as reported the NTSB report. Here
the engine is developing full power and there is lots of heat under
the cowl with reduced cooling air: a prime situation for vapor
formation. And not much altitude so the pilot has little time to
manage the situation.
As with all systems not spraying fuel onto hot metal, induction
icing is a problem.
In all engineering decisions there are multiple compromises. You pays
your money and takes your choice.
Doc Custer
Retired software engineer and sometime Audiologist
Building RV9-A. Fuselage
For everybody that has problems with the Ellison
there are ten that don't. Many people that have
problems with a product bring it on themselves.
Almost all the experimental aircraft that I see
around SZP have Ellisons.
The vapor problems are exactly the same as an aircraft
carburetor up to the fuel bowl. The volume of fuel flowing in the
lines is EXACTLY the same. NO DIFFERENCE! If you use
fire shield insulation on the fuel lines and you keep
them away from the exhaust like you are supposed to do
you will have no problems. Carb ice is mostly triggered by
the carburetor venturi. When you lower air pressure it
cools off just like it heats up when you compress it.
Venturis lower the air pressure. We have no venturis. Yes it
is possible to get ice with a low pressure fuel system
so use alternate hot air like you do with any
carburetor system.
Cessna's are not falling out of the sky all over the
place due to their low pressure fuel systems.
Far more high pressure EFI systems are falling out of the sky
percentage wise due to electrical or EFI system failure of one
sort or another. I investigated a fatal for the FAA.
You want engine quitting? I'll give you engine quitting :)
Try an air bubble on the input to a high pressure EFI fuel pump.
High pressure fuel pumps have a real problem sucking
so they may not recover.
On the other hand your typical $40 Facet low pressure
solid state fuel pump has been sold in the millions and since
it is a positive displacement pump it sucks like a
vacuum cleaner without priming. It is so small,
light weight and cheap you can use four.
Paul,
There is a reduction in pressure after a slide throttle except at WOT. There
is also a reduction due to friction loss in the induction manifold. Both can
lead to ice formation. It's better to have the slide close to the PP.
The valve in a float bowl acts as an automatic vapor vent, a feature which
is missing in a direct feed low pressure fuel system. Maybe an AVV should be
incorporated.
Colin Smith
I agree about the reduction in pressure after a partially open
slide throttle but it is not as bad as a venturi that is always
in the system regardless of the throttle opening. People
takeoff at WOT anyway. With ram air from the prop it could be
an inch or so of Hg above atmospheric.
Also the distance from the slide throttle to the
hot rotary engine is two inches. In a typical Continental
aircraft engine it is 10 or 12 inches from the venturi
to the engine. Lycomings run their intake runners
through the oil pan to heat them.
If you keep the feed pipe cool you won't have vapor
until you want it. The entire system will be under
five psi pressure or 14.7 feet of head from the 2 psi
regulator near the leaning valve all the way back
to the Facit pump near the fuel tanks.
We got vapor lock in the old days because the fuel
tank was in the back of the car and the fuel pump
was on the engine. Also the fuel line sometimes ran
right next to the exhaust pipe. Vapor lock disappeared
when they started putting fuel pumps at the back of
the car or better yet in the fuel tank.
Paul Lamar ...No rotor no motor.
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