Canard Community Forum  

Go Back   Canard Community Forum > Airframe Modifications
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #1  
Old 07-09-2009, 02:54 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Cowl drag reduction

Well, i been thinkin about this for a loooooong time and have finally come up to what i think is a solution.

i know from my trumpet of silence that i can convince the air in a scoop to expand 30% every 2.5 inches, for the outside of the plane i am going to use a curve that is 30% increase every 8 inches and see how that works.

First i'll cut the curve in a piece of cardboard to see how it looks, i've been talkin to experts and they tell me, just make it a true curve that looks good and that will be good enough.

Well, i'm a bean counter and need a reference point and this is what i'll try
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #2  
Old 07-21-2009, 01:38 AM
neverquit's Avatar
neverquit neverquit is offline
G.Norman
 
Join Date: Sep 2004
Location: Lathrup Village, MI
Posts: 1,481
Default Re: Cowl drag reduction

Well, ultimately without driving yourself nutty thinking about it, get the area in which you need to cool or whatever. That'll be your max expansion. Then go forward to your 30% reduction at intake or inlet.
Reply With Quote
  #3  
Old 10-13-2009, 08:36 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

i'm making progress, not on the internet, as usual, but off internet with real sources. A vari guy that has been improving his cowl for 10 years sent me a pic of perrrrrrfect oil lines on his lower cowl.

Talked to him an hour or so last evening and he said he will put a straight edge on and measure the drop every 5 or so inches. I can plot out the curve and run with it.
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #4  
Old 10-14-2009, 11:05 AM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

This is what i am talkin about, when the oil looks like this, you be near perfect
Attached Thumbnails
Click image for larger version

Name:	oiled cowl.jpg
Views:	150
Size:	87.3 KB
ID:	4582  
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #5  
Old 10-19-2009, 12:37 AM
neverquit's Avatar
neverquit neverquit is offline
G.Norman
 
Join Date: Sep 2004
Location: Lathrup Village, MI
Posts: 1,481
Default Re: Cowl drag reduction

check this out...
Attached Thumbnails
Click image for larger version

Name:	trumpet4.jpg
Views:	128
Size:	86.4 KB
ID:	4583  Click image for larger version

Name:	trumpet6.jpg
Views:	147
Size:	63.4 KB
ID:	4584  
Reply With Quote
  #6  
Old 11-09-2009, 12:24 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

Well, a few weeks ago the owner of the cowl sent me the measurements i requested, the drop from the plane of the underbelly to the cowl every 5 inches.

i will plot it out and use it.

So hard to come by real info in this plane building stuff, lots of experts, little real info
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #7  
Old 11-15-2009, 10:58 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

these are the measurments i have from the oiled cowl, have yet to draw them out

Quote:
The 0 point is at the split line of the cowl.
The + dimension is toward the Propeller.
The back of the firewall is at -1.13".
The bottom of the cowl starts up at X=-10.00".

These dimensions were taken as close to the centerline as I could get.
Some locations may be a little suspect like the x=30.00 and/or x=35.00 dim.
Code:
X dim         Y dim
-10.00         0.00
 -5.00         0.31
  0.00         0.75
  5.00         1.69
 10.00         3.31
 15.00         5.38
 20.00         7.50
 25.00        10.00
 30.00        13.12
 35.00        15.12
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #8  
Old 11-27-2010, 04:54 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

finally time to use these numbers! building lower cowl
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #9  
Old 11-29-2010, 10:57 AM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

well, best i can figure, my cowl has upcurve than the one pictured!

I was shocked, but best i can figure is that my intake manifold is on top and not on the bottom

not even really in pour foam yet, will post pics when further along
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #10  
Old 11-30-2010, 11:00 AM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

dam dis be hard, strugled with pour foam last evening, waste of time!

Tonight Steve is comin over, i'll cut 1 x 1/4 foam strips and try to hot glue them on.

It will probably work, hope so anyway
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #11  
Old 12-01-2010, 12:39 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

Cowl is a comin, thanks to steve, he took pics, wonder where they are.

It is ugly and FAST
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #12  
Old 12-02-2010, 01:54 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

http://canardcommunity.com/showpost....7&postcount=17


Hope my cowl tufts out like this one by Lynn
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #13  
Old 12-14-2010, 10:26 AM
neverquit's Avatar
neverquit neverquit is offline
G.Norman
 
Join Date: Sep 2004
Location: Lathrup Village, MI
Posts: 1,481
Default Re: Cowl drag reduction

We were discussing your laminar flow angle in the past and you had decided to keep things 11 degrees or less to keep the air attached. If you use the relationship for your xy dimensions at less than 20% rise to run (11 deg sin is 0.19) you'll keep it in that ballpark.

Just a note, its great to keep things straight and square but don't obscess on it too much to drive you nuts. There's hardly a time you won't have any crosswind component. So unless you're going supersonic, being a bit free on esthetics will be okay. Just my 2C
Reply With Quote
  #14  
Old 12-20-2010, 12:03 AM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: Cowl drag reduction

mmmmm, no crosswind at cruise, you are part of it.

Screw esthetics, fast is beautiful.

2 coats of setting type drywall compound today, then neverquit invited me over for early christmas dinner.

Slowly fine tuning the shape.

currently the right side looks like a camaro and the left side looks like a mustang
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #15  
Old 12-20-2010, 01:12 AM
David Clifford's Avatar
David Clifford David Clifford is offline
Member
 
Join Date: Apr 2004
Location: Howell, Michigan 48843
Posts: 587
Default Re: Cowl drag reduction

Quote:
Originally Posted by Dust View Post
Slowly fine tuning the shape.

currently the right side looks like a camaro and the left side looks like a mustang
So which one will it be,,,,,Camaro or Mustang ??? (you know MY preference!) The pics Steve posted looked awesome and you were gone from your hanger a couple weeks ago when I stopped by to take a look.
__________________
Dave Clifford
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
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 -4. The time now is 10:38 AM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.