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Carbon Dragon Plans on ebay 09 Dec 2013 01:47 #447

The analysis tools I use are PATRAN, as a preprocessor, and NASTRAN as the FE solver. I can read in Step files (.stp), IGES files (.igs), or CATIA files. The step and IGES files are pretty common, and I think most CAD programs will probably write them out. TO do the analysis, I don't think the dimensions have to be super accurate -- that mostly affects the aerodynamics. If the dimensions are within 1/4 inch it's probably good enough. I can use wireframes or solids (if all goes well).




Having the pod down below, would help with some visibility (downward), but wouldn't the upward visibility be worse? It would also help the weight balance as well. What do you think about sweeping the leading edge forward until it's pretty much normal to the airplane axis? That would also solve the weight balance issue somewhat, no? I'm not agin it, just haven't given it that much though. I do like the swift as well, and having the pod below seems like it works OK...




Yeah, Old what's his name keeps yammering on about plywood like there isn't any other way of doing it, but I'm confident he ain't an engineer! I'm sure we can come up with something better, lighter, but most important stronger.




You probably have a good point about the aerodynamics at low speed. The carbon dragon is made for some pretty slow flying. It might be nice to have something that could be either open or closed. depending on the conditions, weather, goal for the flight etc.




You're from Ogden? Are you LDS?





Later, Kenny


--- On Sat, 3/3/12, This email address is being protected from spambots. You need JavaScript enabled to view it. <This email address is being protected from spambots. You need JavaScript enabled to view it.> wrote:


From: This email address is being protected from spambots. You need JavaScript enabled to view it. <This email address is being protected from spambots. You need JavaScript enabled to view it.>
Subject: Re: [Carbondragonbuildersandpilots] Carbon Dragon Plans on ebay
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Date: Saturday, March 3, 2012, 8:34 PM




Kenny,

I have access to SolidWorks I have modeled some ribs and the spar. It is hard to get the assembly to work out perfectly, as in I have not been able to get everything to fit together. I have not even started on the fuselage. I am not sure what the fuselage is doing for performance in the micro speed range. It looks cool and Jim's concept picture on the literature looked a lot lighter. Implementing the concept out of wood turned out to be harder and heavier. I followed the progress of the development and build, took vacation to go to Tehachapi CA and talk to Jim and look at the prototype. I was working in the filament winding advanced composites industry and flying hang gliders cross country. Seeing the prototype was a huge disappointment I was expecting to see a composite glider with a lot of carbon parts! All I could see was a big wooden glider that looked like it came out of the 40's and it was way over projected weight. I now know more about how the Skunk Works worked and have seen some early lifting body stuff under the skin. It was natural given Jim's background to make it look like a conventional sailplane but throws the foot launch static balance off. To me the Swift cage makes more sense and it would allow foot launch. Like a VJ-23 that you could recline in under the wing. The swift cage may be lighter than the wood fuselage. I flew an Ez-Riser for a while and flew a Magic IV hang glider 120 miles. Top end speed was a problem with the Ez-Riser with all the wires and round tubes. The Magic IV would go 50 mph with a decent glide and me in a pod harness. I like the 3 axis control and low sink rate rigid wing but would not mind sitting like a Super Floater a little in front or under the wing. I do not think the un-faired p[ilot would be much more drag at the slow thermalling speeds.

I have been working off of the 1/4 scale scanned pfd and using a steel scale to get non-dimensioned measurements. What kind of input files do you use? Solid models or centerline representations? Full sized plans would make accurate modeling a lot easier but the files I have may be close enough to do FEA on

Regards,

Charlie Johnson
Ogden, Ut

In a message dated 3/3/2012 8:18:36 A.M. Mountain Standard Time, This email address is being protected from spambots. You need JavaScript enabled to view it. writes:


I'm wishing someone would make them CAD files -- that way I could read them directly into the FEM building software I have. Else, I'll have to find time to do it, which means don't hold your breath! And changes for the increased pilot weight etc could be done electronically, which would be a MUCH better way to go about it...

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