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02-17-2013, 05:52 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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K & N filters in heavy rain?
When we departed KEYW last Friday, I pointed out the Alt air knob to my buddy, not knowing how heavy or how long, we'd be in rain, nor do I know how much water the K & N filters in our RV's can handle.
As it turned out, we never needed alt air but I'm still curious as to how much rain they can endure before either A) collapsing, or B) closing off the air supply to the engine.
Ideas/information anyone?
Thanks,
__________________
Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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02-17-2013, 06:28 AM
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Join Date: Sep 2009
Location: St. Louis, MO
Posts: 1,788
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Pierre,
I sent the tech contact @ K&N an email regarding performance in rain. Let's see what they say Monday.
I too was concerned when I flew through some moderate rain a while back. I did notice a substantial decrease in airspeed in the rain (~8kts). This probably due to both airflow over lifting surfaces and high humidity air going into the engine.
__________________
Bill Peyton
RV-10 - 1125 hrs
N37CP
First Flight Oct 2012
Aviation Partners, LLC
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02-17-2013, 06:42 AM
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Join Date: Jan 2005
Location: Venice, Fl
Posts: 1,020
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Good Question
Pierre, Glad you had a good time in Key West.
I don't know the answer to your question but I will relate the following.
While doing IFR training (C-172) in the 70's I was in rain so heavy that I couldn't believe the engine could keep running. It was like several fireman with large hoses were flooding the aircraft/windscreen. The airport (Mansfield, Oh) we were shooting approaches at didn't have weather radar at the time but after we told them of the downpour they contacted KCLE who confirmed we were in the middle of a heavy thunderstorm. I suspect that the RV style filters can perform the same or better than 70's vintage air filters but judging from my experience I don't really want to find out.
__________________
Gary Palinkas - Gman.... VAF #161
Venice, Fl
RV-6 "Sassy" Flying 400 hrs since Oct 2011
Lycoming 0-360 A1A, FP Sensenich Prop
SARL #19 .... Van's Calendar March 2015
Although exempt several ways, =VAF= Dues paid to support this awesome site/family
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02-17-2013, 06:49 AM
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Join Date: Sep 2005
Location: Maple Grove, MN
Posts: 2,333
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Pierre - I'm not sure if the -10's alternate air is the same as my -6A's. If it is the same, closing it might only reduce a bit of the amount of rain coming into the FAB. While most airflow would be directed around the sides of the opening, I'm not sure what percent of the accompanying rain droplets would go with the air vs going straight into the FAB inlet. I suspect most snow flakes would follow the airflow, but rain I'm doubting would.
Good question! (DanH, are you in on this one?)
__________________
Alex Peterson
RV6A N66AP 1700+ hours
KADC, Wadena, MN
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02-17-2013, 07:10 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by pierre smith
Ideas/information anyone?
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Got a metal prop? Do a runup, have an assistant squirt you with a water hose. Start with a fine spray and slowly increase water volume.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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02-17-2013, 07:30 AM
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Join Date: Jan 2005
Posts: 1,009
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Interesting Question
On a couple of occasions, I've flown my normally aspirated 9 thru some of the "red" areas painted by NEXRAD. While the noise in the cockpit was significant, I never noticed a drop in RPM. On the other hand, when I've encountered precip at the freezing level, even in a shallow layer, it has quickly lead to a fall-off in RPM. While this was solved by immediate application of carb heat (shutting off the air box), there's also a corresponding drop in power as I decrease fuel flow to match airflow. Never good on a climbout.
More worrisome for us tip-up drivers is the seal on the front edge of the canopy. If water is dripping on my feet, it's the radios I'm worried about and not the engine. While the seal has been holding well in recent years, I still have my 396 always ready as a backup.
Terry, CFI
RV9A N323TP
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02-17-2013, 08:52 AM
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Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 335
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Quote:
Originally Posted by DanH
Got a metal prop? Do a runup, have an assistant squirt you with a water hose
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Look at a float plane prop and you'll see why that's a bad idea.
__________________
RV-8
Empennage Passed Pre-close Inspection
Wings mostly done
Fuselage is "in the mail"
83126
Dash 8 day job is financing the RV-8
Donation till September 2021
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02-17-2013, 10:51 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by David Z
Look at a float plane prop and you'll see why that's a bad idea.
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I know nothing about floatplane props. Water splash erodes metal or merely removes paint? And why is it different from heavy rain?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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02-17-2013, 11:53 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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Quote:
Originally Posted by AlexPeterson
Pierre - I'm not sure if the -10's alternate air is the same as my -6A's.
Good question! (DanH, are you in on this one?)
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The 10's alt air is in the middle of the air filter, on the bottom of the FAB and activating it doesn't close off the front of the FAB, like our -6A did. It just opens a big, round hole that's centered under the air filter.
Dan, I may just do the water hose trick but how do I relate that to either moderate, or heavy rain?
Best,
__________________
Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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02-17-2013, 01:34 PM
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Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 335
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Quote:
Originally Posted by DanH
I know nothing about floatplane props. Water splash erodes metal or merely removes paint? And why is it different from heavy rain?
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The airflow and vortex patterns in front of the prop at low speed (think taxiing with too much power, or beginning of take-off) suck large water drops into the bottom of the prop arc. They pit and open up the leading edge of the prop. Normally it's just small burrs, but if it's left to get bad, it looks like the metal is peeling apart.
The best picture I could find shows a prop that's already been repaired. The blade tips are no longer nice and round. They're angled off where a mechanic has filed away the damaged part.
http://www.airliners.net/photo/Pacif...e5aba05ba6b409
__________________
RV-8
Empennage Passed Pre-close Inspection
Wings mostly done
Fuselage is "in the mail"
83126
Dash 8 day job is financing the RV-8
Donation till September 2021
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