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09-30-2014, 08:19 AM
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Join Date: Nov 2007
Location: Reno, NV
Posts: 2,125
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Quote:
Originally Posted by dpansier
Bob,
I noticed in one of your photos you have 300 ohm twin lead running down the engine mount, what's the purpose and how does it perform?
Regards
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Don,
That is a Howell Enterprises j-pole antenna for my APRS. It runs from there down the gear leg. I also have a bent-whip in my right wingtip for Comm 2, and have an MFG antenna switch under the panel which can switch Comm 2 and APRS between those antennae. The j-pole works surprisingly well there for APRS, even with the big titanium pole right there. The comm radio is fairly directional, and has some blank spots when using the j-pole in that location. Each does a little better when using the wingtip antenna. Always looking for ways to improve the hidden antenna program, if you have any thoughts!
Cheer,
Bob
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09-30-2014, 10:18 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by Walt
Sorry can't help myself but I have to ask: can someone please remind me what the ACTUAL benefit is to adding all this "stuff" to your engine that has the potential of causing some very serious problems  Please don't tell me to keep the belly clean.
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OK.
The logical reason is a reduction in case air density, and the consequent reduction of parasitic pumping losses. For example, my IO390 pumps 390 cu inches of air through the center main bearing case web with every revolution (195 from the front to the rear case volume, then 195 back again). A 10% reduction in air density requires less power to pump, and supports less aerosol oil.
Same reason your airplane has less drag at altitude.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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09-30-2014, 10:42 AM
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Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,687
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Quote:
Originally Posted by DanH
OK.
The logical reason is a reduction in case air density, and the consequent reduction of parasitic pumping losses. For example, my IO390 pumps 390 cu inches of air through the center main bearing case web with every revolution (195 from the front to the rear case volume, then 195 back again). A 10% reduction in air density requires less power to pump, and supports less aerosol oil.
Same reason your airplane has less drag at altitude.
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Great theory but has anyone proven that it actually increases power in an aircraft application?
The real question is, is the risk vs benefit worth it?
__________________
Walt Aronow, DFW, TX (52F)
EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
Last edited by Walt : 09-30-2014 at 11:03 AM.
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09-30-2014, 11:33 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by dpansier
Bob,
I noticed in one of your photos you have 300 ohm twin lead running down the engine mount, what's the purpose and how does it perform?
Regards
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Yeah! - - - I noticed that too, won't that big yagi be kinda draggy? I was thinking, that is REALLY old school.
Edit: Hey Bob I saw your answer after my post!. Interesting application.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
Last edited by BillL : 09-30-2014 at 11:45 AM.
Reason: added comment
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09-30-2014, 11:36 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by DanH
OK.
The logical reason is a reduction in case air density, and the consequent reduction of parasitic pumping losses. For example, my IO390 pumps 390 cu inches of air through the center main bearing case web with every revolution (195 from the front to the rear case volume, then 195 back again). A 10% reduction in air density requires less power to pump, and supports less aerosol oil.
Same reason your airplane has less drag at altitude.
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You are killn' me here 
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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09-30-2014, 01:01 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by Walt
Great theory but has anyone proven that it actually increases power in an aircraft application?
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Great question!
Mr. Nimmo has twice claimed HP improvement...
http://www.vansairforce.com/communit...9&postcount=17
...here 5 to 8 HP...
http://www.vansairforce.com/communit...5&postcount=35
...and we all want to see the dyno record. How about it Allan?
Heck, even Vic thought he saw a seat-of-the-pants gain:
http://www.vansairforce.com/communit...3&postcount=46
(Sorry buddy, the devil made me do it  )
There are experiments ongoing right now.
Quote:
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The real question is, is the risk vs benefit worth it?
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For some, clearly not. Others would like to pursue the matter, if it can be done with minimal risk, thus the safety valve.
Quote:
Originally Posted by BillL
You are killn' me here 
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How so?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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09-30-2014, 04:49 PM
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Join Date: Aug 2007
Location: Chico (KCIC) , CA
Posts: 264
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My buddy who is also a member here (McFly) added the unit to his plane and says that he got about 150 RPM more static or maybe it was take off, I don't remember, but I know he was conscious of accurately recording the before and after results. He did, however, say that he didn't notice any speed increase on the top end. I have installed the unit, as well, well actually two units - one on each pipe, but have nothing to compare it to as I installed it on a new motor. Before installing them we played with the angle and depth of the tap into the pipe using a water manometer and a shop back blowing through the exhaust pipe. I can't remember for sure but I think the most we could get at any particular angle And/or depth was about 1.5 inches of water which isn't much but then again I'm guessing a 360 exhaust may flow more than a 5hp shop vac.
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09-30-2014, 08:02 PM
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Join Date: Mar 2011
Location: Oregon
Posts: 125
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I highly recommend Anti Splat Aero's Air/Oil Seperator.
Currently installed on our RV6 with Lycoming 160 HP O-320 with constant speed prop.
Also the check valve that goes into one of the exhaust stacks.
Your oil consumption will go to almost zero and you will achieve extra horse power.
Also they have a unit for larger aircraft engines.
Check out their website videos.
AntiSplatAero.com
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10-01-2014, 10:31 AM
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Join Date: Jan 2010
Location: Destin
Posts: 1,543
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i play with big block fords on four wheels, and a common addition to these is a vacuum pump on the case, the idea being that the pistons do not have to push against anything on the power stroke
you gain about 5-10% horsepower with these (electric vacuum pumps)
maybe that's what you guys are experiencing with this?
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10-01-2014, 10:48 AM
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Join Date: May 2006
Location: Houston
Posts: 2,012
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Quote:
Originally Posted by bkthomps
i play with big block fords on four wheels, and a common addition to these is a vacuum pump on the case, the idea being that the pistons do not have to push against anything on the power stroke
you gain about 5-10% horsepower with these (electric vacuum pumps)
maybe that's what you guys are experiencing with this?
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I'm with you in theory. But what rpm are these auto engines turning?? Not certain of the exact relationship, but guessing the drag would be related exponentially to the rpm.
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