Guys, I have to tell you! These airplanes we build are gorgeous creations, and give us lots of bang for the buck! Way back when, Bellanca used to crow about how it got 135 mph on 135 horsepower, and now here are -6s doing 193 mph on 150 HP; Augustus would be mightily impressed! But for all of that, with the go-fast streamlining on these planes, the cooling systems are reminiscent of something the Red Baron would have had on his Fokker! After going to all of the trouble to build this to-kill-for plane, and then totally ignoring the air flow in and out of the cowling is montstrous, to say the least. So many take the output of their oil cooler and just dump it in front of the firewall and hope it will find its way out. Basically the same can be said of the engine cooling air; just have an inlet and place some baffles so that most of the air will find its way through the fins on the cylinders, and then let it find its way out the back! Why bother putting fairings on the gear struts and pants on the wheels? Just use the same thing the venerable old J-3 did and don't even bother with a cowling. Just let the cylinders hang out in the air! If you're going to go to all of the work and time and effort to build this thing of beauty, please at least take the time to put in a low drag cooling system.
Do you know how a jet engine works? It takes in air at its inlet, heats the air up, and then takes this increased volume of air and exhausts it out the back. When you heat the cooling air with your engine and oil, you've created a jet engine, not a very efficient one, but one just the same. When you allow the cooling air to find its way out the back through struts and wires, you take a lot of energy out of it that increases your overall drag. Have you noticed those dropped, streamlined sections on the bottom of the cowling of the Malibu and Cessna Corvallis, nee Columbia 400, nee Lancair ES? That's a duct that takes the air right from the bottom of the cylinders and conducts it smoothly out into the airstream. Each 1% extra speed you get, say 2 mph, is like having 3% more power, 4.5-5 HP! So please, do some experimenting with your inlet and outlet ducting. Make youselves nice expander ducts on the inlet-side to take the air, slow it down to increase its pressure, and then guide it into the cylinders.
And also do some experimenting with the use of your exhaust with an augmenter to help propel the air out the back. I've come up with some very short augmenters that use the Coanda principle to get the air on its way, and I'd be happy to share the drawings with any of you for free. I'd like to see you guys come all the way into the 21st century with your planes. When one or more of you more-daring individuals puts one of these together, you're going to say "This thing will never work!" and then you'll be amazed when you see it, cause everyone who's ever made one had to put the output of the Shop-Vac into it to see if it would work or if they wasted their time.
Do you know how a jet engine works? It takes in air at its inlet, heats the air up, and then takes this increased volume of air and exhausts it out the back. When you heat the cooling air with your engine and oil, you've created a jet engine, not a very efficient one, but one just the same. When you allow the cooling air to find its way out the back through struts and wires, you take a lot of energy out of it that increases your overall drag. Have you noticed those dropped, streamlined sections on the bottom of the cowling of the Malibu and Cessna Corvallis, nee Columbia 400, nee Lancair ES? That's a duct that takes the air right from the bottom of the cylinders and conducts it smoothly out into the airstream. Each 1% extra speed you get, say 2 mph, is like having 3% more power, 4.5-5 HP! So please, do some experimenting with your inlet and outlet ducting. Make youselves nice expander ducts on the inlet-side to take the air, slow it down to increase its pressure, and then guide it into the cylinders.
And also do some experimenting with the use of your exhaust with an augmenter to help propel the air out the back. I've come up with some very short augmenters that use the Coanda principle to get the air on its way, and I'd be happy to share the drawings with any of you for free. I'd like to see you guys come all the way into the 21st century with your planes. When one or more of you more-daring individuals puts one of these together, you're going to say "This thing will never work!" and then you'll be amazed when you see it, cause everyone who's ever made one had to put the output of the Shop-Vac into it to see if it would work or if they wasted their time.