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Old Mar 11, 2014, 10:38 PM
OCD Flying Wing Surgeon
Joined Dec 2013
6 Posts
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Specter Variant - EPS Scratchbuild



I liked the look of the Specter but I wanted to have some different features and flight characteristics, so I hot wired an inspired-by variant with custom geometry and an inverted v-tail out of EPS foam. EPS is brittle, so in order to maintain some strength and rigidity, I used a combination of fiberglass arrow shafts, wood spars, low temp hot glue and various scotch tapes to seal and shell everything. The fuselage was 2x 2" chunks glued together (bay was precut with hot wire hand tools), run through a jig saw, and shaved with a belt sander (gotta love a buddy with a garage).

Flies like this:
New scratch built FPV plane raw clips (3 min 59 sec)


Materials:

- 2" EPS R-type insulafoam from Home Depot
- 3/8" DOW Bluecor (XPS)
- various scotch packing tapes
- 1/4" basswood rods
- fiberglass arrowshafts
- low temp hot glue

Geometry:

Total Length: 32"
Fuselage: 19" long x 4" wide x 3.5" tall
Tail length from end of fuselage: 13"
Nose length from LE: 10.5"

Airfoil: PW51 (1" max thickness)
Total Span: 48"
Inner Chord: 10.75"
Outer Chord: 6.5"
CoG: About 1-1.5" from the LE
Sweep: -2" (-4.5something degrees)
Aileron cuts (used to be elevons): 2" inside inner chord TE narrowing to 1.5"
Rounded tips were cut by stencil and hand sanded.

Boom distance: 10"
v-tail panels: 5" x 7.25"
v-tail control surface length: 1.5"
90 degree anhydral

All up weight: 1.9lbs w/ 2200mah 45C 3S Nanotech

Electronics package listed in the photos.

No OSD or RSSI yet (wish I had a Taranis), but it has room inside the fuselage for all of it and possibly an Orange RX3S flight stabilizer for extra windy days.

Overall, EPS gives it an excellent power to glide ratio. It's got tons of roll authority (high speed drill bit status). It's not Monkey Blunt fast due to its width and shallow forward sweep, but it'll hang like a vulture and get better flight times.






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Old Mar 12, 2014, 09:58 AM
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maurice076's Avatar
United States, MI, Warren
Joined Aug 2011
607 Posts
Nice work,I like how you have everything layed out.One of these days I'll think about getting the gear needed.
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Old Mar 12, 2014, 06:09 PM
All can fly...Launch stronger!
ttersu's Avatar
France, Centre, Romorantin-Lanthenay
Joined Oct 2013
742 Posts
Nice work and great vid!
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Old Mar 12, 2014, 09:30 PM
OCD Flying Wing Surgeon
Joined Dec 2013
6 Posts
Thanks!

I think the motor is pretty overkill on it, so I'm stepping it down to a lighter/smaller Turnigy Park480 1320kv motor for better efficiency.
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Old Mar 22, 2014, 04:31 PM
OCD Flying Wing Surgeon
Joined Dec 2013
6 Posts
Now that spring has finally arrived. I've been able to do some better testing. Conventional flights are getting a consistent 14 minute duration on a 2200mah 3S. Flights entirely made out of power climbs to 200-300 feet with power-off gliding lasted 45 minutes on a 2200mah 3S down to 11.2v.

I'm pretty sure a hot summer day will make it thermal for longer.
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