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Old Jun 16, 2012, 04:13 PM
awrightbrother is offline
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Joined Nov 2007
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Hello all,
It looks like Sam started something interesting here.

The choice seems to be T38 or F5. At first glance the F5 seems to have more inlet area, but I would like to do some CAD measurements to confirm or dispel that.

The F5 does have Leading Edge Extensions, which would help in slow speed flight, more lift, and slower landings. However it also adds a small amount of additional drag. May not be a issue after I take a closer look at that.

The F5 is about 1 ft longer and wider (span) than the T38, and has 16 sq ft more wing area. Not a whole lot of difference when scaled down to 1/4 scale.

So let me study the 3 views that Andy was kind enough to post below and I will get back with my recommendations, shortly.

Meanwhile I would like to answer some of the questions you have asked below:

"AIR SALLY to fit a 90mm fan it has to be pretty bigto get a single fan in there...if your going T-38 you need it bigger as the inlets are very small on the 38,look at some pic of a 38 and a later model F-5 there is a big difference,also the nose ,canopy is diff on a 38.not sure you could do both planes,one or the other. the bigger the better,just scale the inlets to the fan. scale inlet ...what ever the size of the plane."

Doing both planes is a lot of work, so I would like for us to settle on one after I can get you the results of my study. Scaling the inlets to the fan FSA is one way to go, as you suggest, so I will also look at what length and wingspan we end up with if we do that.

"mike2663 Just curious are we talking construction along the "Wowplanes" line or more like what they did on the Falcon5 T-38 construction?"

The construction would be more along the "wowplanes" line. See my website at My A10 would be a good example to look at. The construction is not like a scratch build, where one starts with a block or a sheet of foam. Here we will have pre-cut parts, most already shaped. A few are profile pre-cut and need some minor sanding to get the final shape. The canopy is clear plastic and there may be some other parts in white plastic. The design is done in CAD and the parts are CNC cut by a computer. The quality of the cuts, the precision of the fit, the ease of assembly, is way better than manual foam cutting. I use white styrofoam because I can buy big blocks of it. That reduces the parts count and eliminates a whole lot of gluing that adds weight and failure points. The frame is also lighter and can be made just as strong, if not stronger, with strategic use of balsa, ply, and or carbon fiber.

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