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tonyplane(at)bellsouth.ne
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 Posted: Wed Jan 17, 2007 12:07 pm Post subject: Sensenich Composite Propeller |
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The Jabiru with a Bing Carb with automatic mixture control works fine going up or coming
down on my XL The max altitude I have flow has been 12, 500 ft. Engine purred
going up, going straight and level, and going down. Could have finer EGT
"tweeking" with manual control, which would be ok, but I consider the auto
feature acceptable. With the Jab "economy" carb needle (supplied on newer engines and retrofit on "older" ones)
economy cruising with higher EGT is achieved. I cruise at 4.8 GPM at 120 mph on my "draggy" XL. (bigger tires/wheels - no fairings) at about 6,000 ft. Do not have to worry about going too lean with full power with the Bing.
On the XL/Jab FWF, the air pressure is sensed in the airfilter box which is same as the air pressure going to the engine. Other Jab installations may have other pick up locations which may have some impact on the auto feature mixture control ((i.e. a friend of mine had had extended his carb bowl vent lines about 4 inches below the cowling. This evidently caused a vacuum in the lines when he picked up speed after leveling off, causing the low RPM problem. in his Rotax 912S (also Bings) powered 701. Scared the heck out of him when he leveled off, started picking up speed and then the engine had a dramatic drop in RPM))
Tony Graziano
601XL/Jab3300A; N493TG; 195 hrs
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"I have been reading about issues with the Bing carburetor supplied
with the Jabiru engine on this list and also other Jabiru specific
lists. It seems to me that the "Automatic" mixture control of this
carburetor is little more than an empty promise. While I think the
Jabiru is clearly the best choice for powering a Zodiac XL, I also
think the carburetor is a leading candidate for replacement with a
normal one."
[quote][b]
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p.mulwitz(at)worldnet.att
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| Posted: Wed Jan 17, 2007 5:32 pm Post subject: Sensenich Composite Propeller |
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Hi Terry,
I got the plans on the web and built the probe while waiting for my wing kit. I don't have the web site address handy, but I think you will find it easily enough if you just search on LRI. Also, I think there is a copy of the drawing on one of the big Zenith builder's sites.
The probe is a solid piece of aluminum 1/2" x 1" x 6" as best I can recall. You just need to drill a couple of deep holes and a couple of probe input holes at the other end. Then you need to tap the other end of each hole and install NPT thread hardware to attach the pneumatic tubes. It is all pretty straight forward and takes only an hour or two with a decent drill press - if you don't bother to polish the outside of the probe.
The drawing gives details of the differential pressure meter needed to complete the project. I bought a new one for around $50 from the manufacturer, but others have found them on Ebay for less.
I hope that is enough information. If you need any more just write and I will dig it up.
Paul
XL fuselage
At 10:55 AM 1/17/2007, you wrote:
[quote]Paul, I would be interested in the details of the LRI you built!
Terry Turnquist
60XL-Plans
St. Peters, MO
[b]
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amyvega2005(at)earthlink.
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| Posted: Wed Jan 17, 2007 6:07 pm Post subject: Sensenich Composite Propeller |
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Ed,
You are correct, Prop pitch effects RPm, But not the carborator. Pitch of the prop directly transfers the engergy of the plane into Thrust. Consider the Thrust as Mass of air handled. In these terms, thrust is equal to the mass of air handled times the slip stream velocity minus the velocity of the airplane.
Thus in a simpler term, Prop pitch governs the rpm which is a funtion of the engine working to convert the energy to thurst.
A controlable pitch prop is for requirement of climb or cruise and desired rpm at either. When you fly a plane with fully adjustable prop, you want to convert the energy to thrust, thus you fly the MP setting square to the rpm setting. ex: 2900 RPM AT TAKEOFF IS 29.00mp SETTING. Cruise rpm reduced to 2350 rpm at 75% power setting reduces the required prop setting to 23 to 24.00 MP setting. Thus the term, "fly the squares" The harder the engine works, the more fuel you consume, but you do not touch the mixture on the plane, unless Pressure altitude requires it.
The prop to a certain extent needs to be customized to the engine, that is why the Jabiru requires a certain diameter prop, if not the rpm can cause the tips to go SS, however the lower end torque suffers, so you need a prop that counters the torque reduction on the lower end due to diameter size constraint. A prop
is adjusted for performance desired in the plane , (climb, cruise, etc.).
Where you refer to EGT being effected is the energy not being converted to thrust but heat, the velocity of the plane becomes a factor in the air reaching the fins of the cooling heads, and the fuel going into the engintion chamber is not coling the piston enough. thus higher temps. If properly set between 2 and 4 degrees you will not get High CHT temps.
If you need some books to refer to I can recommend a few. A good read on the topic of props is
Aircraft Systems, By: Dale Demer, Ph.D, Jeppesen Sanderson Training Manuals, 1996.
Juan
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John Bolding
Joined: 23 May 2006
Posts: 281
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| Posted: Wed Jan 17, 2007 6:49 pm Post subject: Sensenich Composite Propeller |
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I have injection molded probes, new gauges and silk screened faces, email me off list if interested. jnbolding1(at)teleshare.net (jnbolding1(at)teleshare.net) John
[quote] ---
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zodierocket(at)hsfx.ca
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| Posted: Wed Jan 17, 2007 7:10 pm Post subject: Sensenich Composite Propeller |
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www.ch601.org builders resources section
Mark Townsend Alma, Ontario
Zodiac 601XL C-GOXL, CH701 just started
www.ch601.org / www.ch701.com/ www.Osprey2.com
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armyret(at)mchsi.com
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| Posted: Wed Jan 17, 2007 7:25 pm Post subject: Sensenich Composite Propeller |
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Paul-Terry- That web site that has the LRI details is www.snyder.on.ca/pages/lri.htm. Regards- Al Young
[quote] ---
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