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Apr 17, 2018, 04:30 AM
Registered User
Build Log

Thresher - twin pusher, swept back wing, Y-tail

Last year I built a ducted prop sweptback wing "jet" that turned out to have great handling qualities, but lackluster thrust from the ducted props.

This year I will build a new model with the same wing planform but twin pusher props behind the straight part of the TE to improve performance, slimmer fuselage and a large Y-tail inspired by the Focke-Wulf TA-183 for flavour.

Called the 'Thresher' for looking kinda like the shark.

A 1/3.5 scale chuck glider flies great!

Projected specs:

Wingspan 70cm
Motors 2 x RCX 1804 2400kv
Props 2 x 5x3x3
Battery 900mAh 3s
Weight: We'll see.... hoping for under 300g
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Apr 17, 2018, 12:05 PM
Scratch building addict
rotagen's Avatar
very unique design!
Apr 18, 2018, 06:43 AM
“There’s no place like Foam”
gpw's Avatar
Pretty Plane !!!
Latest blog entry: Lost plans
May 11, 2018, 10:27 AM
Registered User
I have made some progress, motors are mounted and I've started to glue ribs. Wing construction is 1.6 mm XPS sheets top and bottom, with balsa spar, XPS ribs and a thick XPS LE that will be sanded to shape. Flat bottom over the entire wing and flat top until about 6-7 cm before TE. Total wing thickness will be ~13mm.
May 11, 2018, 12:10 PM
Registered User
...and thanks for positive comments rotagen and gpw, I will try to make it pretty and unique Seriously contemplating adding a central split flap, with landing gear fairings acting as end plates to increase effect of the flap.
May 12, 2018, 07:21 PM
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Laminated the ailerons and began tail construction today. I made the tail swept 60 degrees, a wee bit more than the test glider. I don't want the tail to look so weirdly tall!

The tail is built using the same technique as the wing, but symmetrical. At 25mm thick is will almost be more an aft fuselage than a tail, as this is almost double the thickness of the wing.

So far AUW is 200g; that's without receiver, two 5g servos, split flap, front fuselage, landing gear, v-part of the tail, and some XPS sheeting. Hoping I'll make 300g when it's done!
May 14, 2018, 03:46 PM
Registered User
Some progress on the tail
May 14, 2018, 06:53 PM
If it flies - I want one!
Petem's Avatar
Excellent! I have always liked unusual layouts and that one is very attractive as well as practical.
With the wing structure, do you shape the ribs and centre layer before fitting the upper skin?
And will the tail have elevators fitted, or do you just use elevons for control?
Good to see you have plenty of wheels available for the project!
May 14, 2018, 11:33 PM
Registered User

The LE and the center part of the wing is completely flat when fitting the upper skin, the rearward part of the ribs aft of the spar are cut and sanded to a curve. Then the skin is glued on and let cure, after which the LE is shaped out of the front foam strip using a scalpel and sanding block.

The tail will have elevators / rudders in V-tail mixing, I'm currently deciding on wether or not to attempt to hide the control horns in the central fairing.

The wheels are for something a bit larger, for which I am to pick up a few kilos of wood later this week
May 29, 2018, 04:49 PM
Registered User
All four essential control surfaces are connected to servos, next step is sheeting the tail and install the split flap, then mount the tail assembly to the wing.
May 30, 2018, 08:41 AM
Registered User
Tail is sheeted, fairings around the Y-tail intersection have been smoothed out and the LE rounded. Now on to building the split flap, finish the nacelles and sheet the remaining part of the wing before mounting the tail and starting the fuselage!
May 30, 2018, 07:40 PM
If it flies - I want one!
Petem's Avatar
Moving along nicely, and looking good! Flight trials awaited with interest.
Jun 04, 2018, 03:27 PM
Registered User

Flap done

Installed the flap mechanism and glued on the tail. The geometry is chosen so the servo arm is parallel with the pushrod when the flap is deployed to minimise load on the servo.
Jun 13, 2018, 09:03 AM
Registered User
Fuselage taking shape!

I redid the flap to move the linkage towards the center as I realised that the fuselage width approaches the width of the vertical tail at the point where the flap is located. Now I don't have to make any cutouts in the fuselage sides for the servo arm or control horn, much better than the first installation!
Jun 13, 2018, 05:09 PM
Registered User
At least it looks fast

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