VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.

  #1  
Old 07-31-2019, 04:50 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 10,352
Default Nice Filtered Inlet

One of the best RV ideas I saw at OSH was this intake for an airbox with a large area K&N filter. The concept could probably be used with a modified Vans airbox for the vertical intake engines also.

The problem is how to put the lower cowl on the airplane while dealing with the connecting seals or ducts. Here the builder has fabricated an aluminum sleeve. It is inserted after the cowl is in place, slipping inside the orange duct leading to the airbox. It is then fixed into place in the cowl with two screws.

Am am deeply ashamed to say I can't remember whose airplane this was, despite talking with the builder for a few minutes. Claim it please, and kick me next time you see me

Great idea, and beautifully done.





__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #2  
Old 07-31-2019, 05:02 PM
snopercod's Avatar
snopercod snopercod is offline
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 2,122
Default

I did something similar using a K&N conical filter. I cut off that protrusion on the left end:



I glassed up a ram airr intake diffuser with a 2-3/4" opening, expanding at a 7 degree angle on either side, ending up at 4" dia. I think it's about 11" long. My calculations told me these dimensions would slow the air down from my usual cruise speed of 200 mph to more like what the engine was sucking in. You can sort of see how it all fits together in this photo. The intake diffuser is connected to the airbox with a 4" piece of scat tube. The fiberglass airbox itself transitions from 4" round to a 4" wide x 3" tall rectangle, where the carb heat flapper resides. It's a balanced teeter-totter flapper: Ram air from the front and carb heat from the rear:



The K&N filter slides into the airbox itself. This RTV job is "temporary" (yeah, fooling myself again). That 2" scat duct was the carb heat, but I've changed that installation. The heated air still enters the airbox from the rear, though.

__________________
(2020 dues paid)

Last edited by snopercod : 07-31-2019 at 05:21 PM.
Reply With Quote
  #3  
Old 07-31-2019, 05:45 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 10,352
Default

Well, not so similar...

The blue cowl is one piece. Slips on without airbox issues, after which the only remaining step is inserting the tube.

The 4" cone filter with limited pleat depth will be quite a lot more restrictive when compared to a large flat K&N with 7/8" pleats. Part of the appeal here is how well the builder enclosed the large airbox.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #4  
Old 07-31-2019, 09:03 PM
Ron77 Ron77 is offline
 
Join Date: Jul 2017
Location: Kemah, Texas
Posts: 115
Default

Looks like Kevin Taylors?s RV8 with DH inspired FAB.

Ron B
Reply With Quote
  #5  
Old 08-01-2019, 01:33 AM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,971
Default inlet diffuser?

Dan, How does the aluminum tube and orange rubber sleeve transition to the large face of the filter?

This is an area where the diffuser needs to be designed well. Short wide-angle diffusers can often perform better than a long shallow angle diffuser, but the curvature and expansion rate must be managed carefully.
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 700
also
1/4 share in 1959 C-182B (tow plane)
LS6-15/18W sailplane SOLD
bought my old LS6-A back!!
VAF donation Dec 2020
Reply With Quote
  #6  
Old 08-01-2019, 07:59 AM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 10,352
Default

Quote:
Originally Posted by Ron77 View Post
Looks like Kevin Taylors?s RV8 with DH inspired FAB.
That sounds familiar. Hope he checks in here and takes a bow.

Quote:
Originally Posted by scsmith View Post
Dan, How does the aluminum tube and orange rubber sleeve transition to the large face of the filter?

This is an area where the diffuser needs to be designed well. Short wide-angle diffusers can often perform better than a long shallow angle diffuser, but the curvature and expansion rate must be managed carefully.
The owner didn't remove the cowl, so I don't know the airbox shape. Nor did I note the tube diameter.

That said, the inlet velocity is probably low. For example, assume 3"D tube, 2400 RPM, 360 cu in displacement, and 0.95 VE. Velocity through the inlet would only be about 48 knots, thus diffusion at any practical cruise speed must be largely external, making the airbox entry shape not so critical. A 2"D would be about 68 knots.

Like the external shape at 3 and 9 o'clock? 6 o'clock is maybe a little sharp? Think there would there be a separation penalty there? The overall aesthetic is so attractive that I would be loathe to change it, regardless.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #7  
Old 08-01-2019, 10:31 AM
bkthomps bkthomps is offline
 
Join Date: Jan 2010
Location: Destin
Posts: 1,546
Default

just make sure you have an alternate air setup....that is a great ice collector
Reply With Quote
  #8  
Old 08-01-2019, 12:05 PM
KGT KGT is offline
 
Join Date: Feb 2018
Location: Rosemount MN
Posts: 21
Default Yes it?s mine!

Thanks for the nice comments Dan. Actually the silicone tube clamps to the aluminum tube and slides out a few inches to allow easy cowl removal. I made a DH inspired air box as well!

Kevin Taylor
N84KT
Reply With Quote
  #9  
Old 08-01-2019, 01:24 PM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,592
Default

I used the same conical K&N filter (Bendix injection on Superior forward facing cold air sump, James long cowl). I cut down the rubber flange on the large end until it fit nicely in the fiberglass cone and RTV'd it in place. The fiberglass cone is then screwed into the face of the Bendix injection.



The front side of the cone attaches to the snout on the James long cowl with a neoprene ring and band clamp, easy to access and remove in about 30 seconds with the top cowl removed. This shot is kinda hard to see, looking down from the top but you can make it out.

__________________
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2021 dues paid
N16GN flying 900 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, IFD440, G5
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
Reply With Quote
  #10  
Old 08-01-2019, 02:55 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 10,352
Default

Quote:
Originally Posted by KGT View Post
Actually the silicone tube clamps to the aluminum tube and slides out a few inches to allow easy cowl removal.
So the orange silicone tube slides into the airbox?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 04:47 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.