PaulL Posted August 4, 2004 Share Posted August 4, 2004 I noticed that some canard cowlings have two round air exit ports and some simply have one large opening at rear. What are the pro's / con's of each. I have two holes. Will a single larger opening improve cooling? Quote Link to comment Share on other sites More sharing options...
Jon Matcho Posted August 4, 2004 Share Posted August 4, 2004 Paul, I asked the [C-A] group to give their $0.02 on this. We'll see what happens. I'm not going to hazard a guess on this one. Quote Jon Matcho Builder & Canard Zone Admin Now: Rebuilding Quickie Tri-Q200 N479E Next: Resume building a Cozy Mark IV Link to comment Share on other sites More sharing options...
Jon Matcho Posted August 5, 2004 Share Posted August 5, 2004 Paul, here's what Terry Schubert had to say on this: Dear Jon, My testing shows no difference. The round outlets are so large that there is no obstruction. If the outlets were down around 12 sq inches each then maybe the separate outlets might have an advantage in accelerating the outlet air and then recover some lost energy. The separate outlets may also offer increased stiffness. Good luck, Terry Schubert Central States Association Newsletter Editor I didn't even think about stiffness... Quote Jon Matcho Builder & Canard Zone Admin Now: Rebuilding Quickie Tri-Q200 N479E Next: Resume building a Cozy Mark IV Link to comment Share on other sites More sharing options...
Spodman Posted August 5, 2004 Share Posted August 5, 2004 I think the difference may be the type of Cozy you're looking at. The open-back one is a Cozy III with an O-320, the circles a Cozy IV with an O-360. This applies to the Featherlite cowl, build your own you can make it how you like, let alone if you have bolted on some automotive-hybrid monstrosity and can't use the Featherlite. Shipping costs mean I'll probably build my own. Somebody feel free to tell me I'm wrong. Quote Mark Spedding - SpodmanDarraweit Guim - AustraliaCozy IV #1331 - Chapter 09www.mykitlog.com/Spodmanwww.sites.google.com/site/thespodplane/the-spodplane Link to comment Share on other sites More sharing options...
ZUCZZ Posted February 4, 2008 Share Posted February 4, 2008 My question on this topic is "what is the airspeed" as it leaves the cowling? Does it create drag? if so how much? How can one get the best exit speed while maintaing the efficient cooling that the standard cowl gives. OK, I do have in cowl pipes & no more than 1/2" spacing anywhere to the motor. Just wondering. Quote I live in my own little world! but its OK, they know me here! Chris Van Hoof, Johannesburg, South Africa operate from FASY (Baragwanath) Cozy Mk IV, ZU-CZZ, IO-360 (200hp) 70x80 prop Link to comment Share on other sites More sharing options...
Aiman Posted February 4, 2008 Share Posted February 4, 2008 ....automotive-hybrid monstrosity..... Somebody feel free to tell me I'm wrong. You are wrong. Quote Link to comment Share on other sites More sharing options...
TMann Posted February 4, 2008 Share Posted February 4, 2008 OK, I do have in cowl pipes & no more than 1/2" spacing anywhere to the motor. Just wondering. I can't speak to the aircooled engine applications but for water cooled I learned the following:I spoke with a very savy engineer in St. Charles, MO about this and if memory serves me correctly, it goes like this. The duct work needs to expand by 400% (in reference to the inlet) by the time it gets to the radiator for a water cooled engine. The exit dimensions are 150% of the inlet dimensions. Quote T Mann - Loooong-EZ/20B Infinity R/G Chpts 18 Velocity/RG N951TM Mann's Airplane Factory We add rocket's to everything! 4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done Link to comment Share on other sites More sharing options...
Waiter Posted February 5, 2008 Share Posted February 5, 2008 while maintaing the efficient cooling that the standard cowl gives.Unfortunantly, the standard cowl sucks. It does a good job but isn't very efficient. The numbers TMann provided seem reasonable. The key is to find the intake area that will provide the desired pressure differential at the desired airspeed. In my downdraft design, I'm using 10 sq in per side for the cylinder plenums (20 sq in) and 4 sq in for the oil cooler. I'm providing about 35 sq inches for exit area. These may be to large, but I can always close them down later by placing "lips" on the intake ramps. A Gold Mine of reading on this subject is from the NACA Report documents. Hey, it was your tax dollars at work, so read up on the research. http://ntrs.nasa.gov/search.jsp Try searching "Cooling Drag" Enclosed is one I've been reading throught Waiter 19980214913_1998122345[1].pdf Quote F16 performance on a Piper Cub budget LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract visit: www.iflyez.com Link to comment Share on other sites More sharing options...
rviglierchio Posted February 5, 2008 Share Posted February 5, 2008 Great stuff Waiter! Really good sources. Much more helpful than: "You are wrong. " Found some good info on scoop drag that I've been looking for. Thanks again! Quote Link to comment Share on other sites More sharing options...
Aiman Posted February 5, 2008 Share Posted February 5, 2008 lol.. i was just saying that he was being a little closed minded about auto engine conversions by calling them 'monstrosities' Quote Link to comment Share on other sites More sharing options...
ZUCZZ Posted February 5, 2008 Share Posted February 5, 2008 Thank you for the link, will do the reading. Regards Quote I live in my own little world! but its OK, they know me here! Chris Van Hoof, Johannesburg, South Africa operate from FASY (Baragwanath) Cozy Mk IV, ZU-CZZ, IO-360 (200hp) 70x80 prop Link to comment Share on other sites More sharing options...
ZUCZZ Posted February 5, 2008 Share Posted February 5, 2008 This may not be the pertinent information that I am looking for. It deals with the flow as experienced by the "puller" type plane. An RV feller here in South Africa installed an air speed probe in an RV plane and measured 35 Mph at the cowling exit. This is my real question, what is our airspeed as it exits the cowling. Where would be the best position to measure this ... I am to install an airspeed probe & lead this to the front of the Cozy to take a reading. My first position is inside the cowl, facing forward between my exhausts & the flange. closer to the exhausts (may want to fix to that) Your suggestions welcome! Quote I live in my own little world! but its OK, they know me here! Chris Van Hoof, Johannesburg, South Africa operate from FASY (Baragwanath) Cozy Mk IV, ZU-CZZ, IO-360 (200hp) 70x80 prop Link to comment Share on other sites More sharing options...
Neverquit Posted February 5, 2008 Share Posted February 5, 2008 My first position is inside the cowl, facing forward between my exhausts & the flange. closer to the exhausts (may want to fix to that)I think Terry Schubert might have some good information on that. Great read Waiter. I can see hours and hours of reading pleasure in my future. Quote Link to comment Share on other sites More sharing options...
CBarber Posted February 5, 2008 Share Posted February 5, 2008 OMG, I AM SHOCKED!!!! A discussion on a topic supported by solid documented research and testing. What is this forum coming to? All the best, Chris Quote Christopher Barber Velocity SE/FG w/yoke. Zoom, zoom, zoom. www.LoneStarVelocity.com Live with Passion... Link to comment Share on other sites More sharing options...
ZUCZZ Posted February 5, 2008 Share Posted February 5, 2008 Cb, I obviously did not know, what with living in darkest africa & all. Quote I live in my own little world! but its OK, they know me here! Chris Van Hoof, Johannesburg, South Africa operate from FASY (Baragwanath) Cozy Mk IV, ZU-CZZ, IO-360 (200hp) 70x80 prop Link to comment Share on other sites More sharing options...
ZUCZZ Posted February 6, 2008 Share Posted February 6, 2008 The reading suggested above is not applicable to pusher type a/c, if I understand anything at all ... The Cafe Foundation does have a lot of info on their site, also mostly on tractor set-up planes ... cannot help but wonder why However, in the exhaust section at : http://www.cafefoundation.org/v2/pdf_cafe_reports/EPG%20PART%20IV.pdf the following interesting tidbit is extracted from page 11: 8. Exhaust jet thrust was measured and calculated for several exit sizes, RPM’s and fuel flows. It can produce significant thrust at high power settings, especially at cruising altitudes.6 But my question still stands ... what is the airspeed of the air as it leaves the cowling. Regards Quote I live in my own little world! but its OK, they know me here! Chris Van Hoof, Johannesburg, South Africa operate from FASY (Baragwanath) Cozy Mk IV, ZU-CZZ, IO-360 (200hp) 70x80 prop Link to comment Share on other sites More sharing options...
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