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::: CO5 ::: ::: Higgin's T-38 Talon
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Plane: CO5
The purpose of this project is to produce an inexpensive high
performance plane that will fill the role of a light-med wind
inland sloper. Thermaling and DS performance will be of utmost
importance. I chose the CO5 for the following reasons: 1. Wings are fast for their wing-loading. 2. From my experience with the Razor1 wings DS very well,
and they both use the MH 45 airfoil. 3. Wings can be built cheap. 4. This is a proven design of Hans-Jurgen Unverferth. 5. Plans are readily availiable from Andy MacDonald's Flying
Wing Page at
http://www.cs.net.au/~andy/HJPAGE.HTM There are a couple of changes I'll be making to the plane.
This is not to second guess the designer, but to allow for ease
of construction. 1. The span will be reduced from 98.5" to 94". This
is the result of using T&G blue foam which yields a 23.5"
width. 2. There won't be any flaps. This plane won't be performing
spot landings and won't be so heavy that flaps will be needed
to slow it down. This will also keep the cost down, simplify
building and reduce the possibility of flutter. 3. Using the Panknin Twist spreadsheet and John Hazel's Lift
Distribution spreadsheet, I modified the amount of washout to
match the changes, weight and flying conditions of the plane.
Weight of the lay-up was calculated with Joe Wurt's lay-up spreadsheet
for a velocity of 150 mph. The spreadsheet is availible from
the US F3b homepage.      Lay-up Bottom - 1.4 FG bias, 4.7 CF uni full length Top - 1.4 FG bias, 4.7 CF uni full length, CF Root out to 30", CF Root out to 20", CF Root out to 12"  In the bag. There is a full length piece of angle iron under the TE. The aluminum angle on top of the wing is lightly weighted to hold the wing on the lower shucks and to make sure the reflex in the foil is true.     Flying impressions. At this point I have well over 30 hours on the plane in various conditions and at multiple wing loadings. At a 73 oz flying weight (12oz/ft^2), it is definately a floater. While it will climb nicely in thermals it is almost too light to cruise at an efficient glide. After adding 20 oz (15 oz/ft^2) of ballast the plane cruises very well and is flown at this weight in all but the lightest lift. The additional weight is appreciated by the CO5 and the plane can really cover some sky at this weight while still being able to pylon turn like a superball. With 48 oz (20 oz/ft^2) of ballast the plane is fine in front of the hill but the turning performance is compromised. Dsing is more pitch stable with the weight (20 oz). The added weight allows for larger circles. The plane flies well behind the hill but does'nt track as well as some of my other planes. If you pop up out of the line it takes quite a bit of work to get back into the line compared to the Nova. When you get spit out with the CO5 you tend to get way out of the line. With the Nova you don't get as far out of shape and can easily spiral back down into the groove. At 20 oz/ft^2 the plane undergoes spanwise oscillations when dropping into the dead air behind the hill. Not good. Another basic problem behind the hill at any wing loading is the tendency for the plane to drift into larger circles. You really have to work to maitain the same size circle as the speed builds. Overall the project is a success. I was hoping that the plane would perform better at the higher loadings, but that is what the Big Mother is going to do. The total cost of the airframe was $110, including mylars. Ready to fly at $300. It fills a valuable niche in the arsenal for a minimum amount of cash.
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All Content © Craig Toutolmin |
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