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Author Topic: Nightmare  (Read 504 times)
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Jastafuhrer 13
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« on: January 14, 2020, 10:52:50 AM »

My latest project is the Nightmare by Al Casano. Plans found here https://outerzone.co.uk/plan_details.asp?ID=2257 I have a soft spot for twin fins, single blade folders, and odd models. I'm building by the plan with a couple of exceptions. The accompanying article states that a 25 degree sweep was used, however the plan is actually drawn at 30 degrees. I redrew the wing and stab plans for 25. Center ribs on the wing were canted 12 degrees to get the 3.25“ dihedral. I messed up a little by gluing the wing saddles on the fuselage before tissue, so I will add some light blocking inside the top longerons to catch the tissue. So far it's been a fun and straightforward build.
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Starduster
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« Reply #1 on: January 14, 2020, 11:38:11 AM »

I can't hardly wait for the flight reports!!!

Looks good, though...
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"We have done the impossible, and that makes us mighty..."
Jastafuhrer 13
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« Reply #2 on: January 17, 2020, 12:11:39 PM »

 The article states "Performance is unusually good" but my expectations are set low.  The wing is rather large at approximately 150 sq in for 28" wingspan.  The hair clips on the wing are to keep it from tipping forward while it's just sitting there.  The center of lift seems like it will be pretty far forward. 
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strat-o
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« Reply #3 on: January 17, 2020, 02:28:56 PM »

Initially I was thinking that even with the wing pretty far back it would be tail heavy but then I noticed the stabilizer area being so large, it would act more like a tandem surfaced airplane like the Mauboussin Hemiptere.  My interest is now piqued.

Marlin
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Jastafuhrer 13
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« Reply #4 on: January 17, 2020, 03:03:29 PM »

The is no CG shown on the plan so I entered the wing geometry into this calculator https://www.ecalc.ch/wingdesigner.htm to find where the approximate aerodynamic center of this configuration would be.  See attached picture.  In side view it's about where the letter "N" in Nightmare is on the plan above.   The center of the stab is farther back than it first appears on the plan.  It's no surprise that the wing saddle is oversized in length. 
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Jastafuhrer 13
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« Reply #5 on: January 27, 2020, 05:17:27 PM »

I carved a prop based on the plan dimensions and it just doesn't feel right.  It's 15" diameter on a 28" wingspan, with approximately 1.5 P/D.  The blade chord is nearly 2.5" at the widest station.  It really looks like a flyswatter up there (it's the prop sitting on the table below).  I held the prop from my Hep Cat up to the Nightmare and it looked about right and is 13.5" diameter with less pitch so I'm guessing that should work okay.  I used Barker's 2004 Hep Cat plan and carved the prop for the wire hub version (my HC uses the plywood hub version.) This is new territory for me so I spent a fair amount of time scratching my head over the compound angles of drilling the blank.  Seems like it turned out okay and folds nicely on a test prop shaft. I've been following Caley's SBF progress on the Baron Knight thread and I understand the frustrations.

I also got a plug in landing gear fitted and a pair of balsa/ply wheels turned. 
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Jastafuhrer 13
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« Reply #6 on: February 06, 2020, 04:34:48 PM »

The plans on this show a rudder tab hinged on soft iron wire in the edge of 3/32 sheet. I'm using a twist tie for wire and I'm having trouble gluing it in the holes. What kind of glue to use? And how?
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OZPAF
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« Reply #7 on: February 06, 2020, 09:12:40 PM »

As a suggestion I would use CA - possibly medium to give a bit more time. Glue the wires into the tab first and then insert them into the holes in the fin, placing a strip of clear tape between them. Add a small amount of CA to the wire - use a small wire applicator, and use it sparingly. This shouuld work but try it out on scrap first.

Nice work on the wings, tail and fuse.

Talking about the CG - the geometry of the wing and tail is interesting after you get used to the appearance Smiley as it provides good moments with a shortish fuselage.

It will be interesting to see how it performs.

happy flying

John
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