The Variant - another take on a twin-boom pusher

by jamesomega | May 15, 2014 | (13) Posted in Projects

I liked the look of IBCrazy's forward swept Specter but I wanted to have some different features and flight characteristics, so I hot wired an inspired-by variant with custom geometry out of EPS foam with an inverted v-tail. EPS is brittle and doesn't hold up well to crashes, 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" EPS blocks glued together (bay was precut with hot wire hand tools), ran through a jig saw, and shaved with a belt sander (gotta love a buddy with a garage). The ailerons are a bit crazy for this wing, but that's only because they used to be elevons for an Alulah style powered pusher glider (which also flew awesome, but that's for a different article).


Flies like this:

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

The motor in the photos turned out to be a touch overkill for the kind of flying that I wanted to do, so I ended up switching the motor out to a Turnigy Park480 1320kv with an 8x6 APC-E.

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

Electronics package listed in the photos.

No OSD or RSSI yet, 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). Flight times range from 12 minutes cruising around, or a boring 50 minutes of endurance testing entirely made up of power climbs and throttle off gliding in high winds.

 Here's some FPV practice footage from it side by side with footage from my friend's new twin engine fpv prototype under development:

 

COMMENTS

GB-air on May 29, 2014
Wow! That might be the best looking FPV plane I have ever seen! This article makes me want to make one, but I'm sure it won't turn out looking as beautiful as yours.
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jamesomega on May 29, 2014
Awe thanks! You totally should make one! I'm actually working on an article on how to make a better/finer resolution hot wire cutter power supply. If you've got easy access to EPS and a long table to cut on, you could be swimming in wings. :)
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GB-air on May 29, 2014
That sounds really cool! I have some two 30" sheets of EPS sitting in my garage, a long table, and a hotwire. Since I am just getting into FPV, a plane like this will be great for me. Let's hope the magic happens!
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GB-air on May 29, 2014
Oh, I just saw that you are in NoCal. I am just south of San Francisco. You anywhere near there?
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PabloJaime on May 29, 2014
Nice plane!!!!
But why to use a gopro as FPV cam?? that's is a nice search for problems...
And why to put a Filter in your VTX if you are flying with 2.4Ghz on control??
Have fun!!!
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jamesomega on May 29, 2014
I mainly use a GoPro because it's what I have. It also saves weight to carry one camera rather than two, but it's not an all weather camera outside of its case - it's not a good idea to fly in weather that's too hot or too cold or else it could shut down on your randomly. I've tried a few security cameras in the past but didn't like them.

The low pass filter on my VTX prevents the 1.2ghz signal from creating a harmonic on 2.4ghz. If you don't have a filter on your 1.2-1.3 system then it could/will interfere with your control signal and reduce your overall range. That's why most people like 5.8ghz because there's nothing above that frequency to interfere with your control over the craft.
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TehMaxwell on May 29, 2014
Awesome plane, perfect for FPV, from what you have described it does the whole package. Long Range and High Speed Close to home flying! And to top it all off it looks awesome!
Great Plane!
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jamesomega on May 29, 2014
Thanks, I think it worked out well although I do kinda wish it was a little bit faster. It's a good balance of efficiency and speed all around though, you should make yourself one! :)
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TehMaxwell on June 1, 2014
I may just do that! :D I currently fly a versa wing with FPV Gear on it, its fantastic and does the job very well, however flight times are short as I cannot fit very big battery's inside it. This may be the answer to my flight time problem!
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Piers283 on May 29, 2014
Nice annotations, looks professional. Nice Build.
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Willsonman on May 29, 2014
What is the music in the video?
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DBellhorn on May 29, 2014
Petrichor by Koven according to the video's description.
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jamesomega on May 29, 2014
Yep, you got it. Thanks for replying for me. :)
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Flying kid on June 2, 2014
Starting my own v tail hopefully posting something soon
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jamesomega on June 11, 2014
That's awesome! They're really fun to fly and very stable.
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HilldaFlyer on June 5, 2014
Great plane. I built an inverted "V" tail from scratch last year, but I didn't take any pictures of it while it was in one piece. I liked the way the inverted "V" produced roll when rudder input was given - made flying really smooth.

Keep your eyes open - I just finished a twin boom pusher using the FT Cruiser wing with the end goal of FPV. I'm in the process of making a build article.
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jamesomega on June 11, 2014
Coordinating turning on a v-tail is great, and I'll definitely keep my eyes peeled for your article. Sounds like an awesome plane you've got in the works.
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corsair pilotnatel on June 19, 2014
looks cool and flies cool as well
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The Variant - another take on a twin-boom pusher