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Old Feb 03, 2009, 12:19 AM
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San Jose, CA
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CAD Design Started .....

The scratch build started from a virtual world ......

Step #1 - airfoil selection/simulation
Step #2 - main wing, elevator, rudder definition
Step #3 - fuselage construction
Step #4 - put all the parts together

This is a lot easier than building the real one.
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Old Feb 04, 2009, 12:00 AM
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Let the PC do all the works ......

A combination of airfoils and tilt angles for front and main wing examined.
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Old Feb 07, 2009, 03:31 AM
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Virtual world is quite different from real work perception. Planning on the 48" span but the fuselage is just unbelievably large. A 85% linearly scaled fuselage of 48" model seems to be a right size.
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Old Feb 07, 2009, 12:38 PM
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MG06, AG45c or Both ?

Two final contenders for airfoil selection. This pair seems to meet the following stability requirements from "The Text Book".

Two requirements are critical for stable flight:
- The front wing must stall before the main wing stalls
- The main wing must arrive at it's angle of zero lift before the foreplane achieves the zero lift

I'm also consider using the same airfoil for both front and main wings. Not sure how bad it will be on stability? Not sure which one will go faster in real world? MG06 or AG45c?

Geode
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Last edited by Geode; Feb 07, 2009 at 02:27 PM.
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Old Feb 07, 2009, 12:49 PM
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Here is the preliminary target

Mass - 800g / 28.3 oz (guestimation)
Span - 122 cm / 48 in
Front wing area - 13.55 dm2 / 210 in2
Main wing area - 14.40 dm2 / 223 in2
Wing loading - 9.4 oz/ft2
Front / Main Wing aspect ratio - 8.2 / 10

Hope it's not too heavy to fly on my home slope.
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Old Feb 07, 2009, 02:07 PM
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San Jose, CA
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Block Cutting

It's been raining for some time. Things start to get rusted on bolts and nuts

It's sunny and warm today in the sunroom/workshop. Time to warm up the machine and cut some EPP
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Last edited by Geode; Feb 08, 2009 at 01:09 AM.
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Old Feb 07, 2009, 09:53 PM
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Plan is ready and the CNC cut files generated for CNC hot wire foam cutting...... Ready for some real action.
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Old Feb 08, 2009, 10:22 AM
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Been scratch my head for fuselage in the past few days .....

Love the fuselage of commercial EPP kit. Simple to made, but a lot of carving and sanding to round up the fuselage after EPP cut.

Considering chop the fuselage into 4~5 sections (something like this Duo Discus, but not exactly) . Hot wire cut to rounded shapes for each section then join together. A lot less sanding work needed, better matching between left/right halves, but might need some extra work for EPP preparation.

Any other "quick and easy" way for EPP fuselage formation?

Thanks,
Geode
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Old Feb 08, 2009, 10:25 PM
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With something as sleek (and weak *tailsection*) as that, I'd lean to cutting the fuse outline onto blue foam, sanding it to shape and then doing a lost foam fuse. I think about me trying to get an epp block reinforced and shaped like that and I'd end up with a very heavy epp fuse. I think you'd want it light for crash survivability, and no need for a bounce-able fuse, just a bulletproof 'hedral joiner and bouceability for the forward/anhedral wing.
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Old Feb 09, 2009, 09:52 AM
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I agree. Got to keep it light for crash survivability. And yes, I really don't want to repair the fuselage or the wing join on a regular basis.

I was thinking about EPP fuselage with CF rod re-enforcement. Hope this will bail me out of the troubles. The wing joint is a real headache. But you got a great point. Flexible for the front wing joint (just like the regular landing wheel) and firm for the main wing joint. I like the idea. Will do.

Thanks.
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Old Feb 10, 2009, 12:49 PM
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Fuselage Template

Slice up the fuselage. A few hours later, templates are ready for fuselage shaping. Now, waiting for EPP shipment.
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Old Feb 12, 2009, 04:48 PM
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Last piece of template before EPP cutting.....

Front & main Wings - done
Vertical tail - done
Fuselage - done

I should have everything covered. Ready to set for the real work soon.
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Old Feb 13, 2009, 02:02 AM
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... Now the fun begins!

It looks GREAT ...

Bill
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Old Feb 13, 2009, 10:41 AM
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Thanks Bill.

Can't wait to get back home to see the Fedex man bring home the EPP.
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Old Feb 16, 2009, 04:01 PM
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Some EPP cutting action in progress ......
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Last edited by Geode; Feb 16, 2009 at 04:10 PM.
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