yet another scratchbuilt twin boom pusher - Page 3 - RC Groups
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Mar 30, 2012, 11:16 PM
400' ..... NOT
Martin Y's Avatar
What did you do with the twin* fus?
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Mar 31, 2012, 06:19 AM
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xatled99's Avatar
I never had it; I bought the wing a la carte.
Mar 31, 2012, 12:09 PM
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xatled99's Avatar
All dressed up and ready to go. 460W at 32A on 4s with an APC 11x6, 9500 rpm.
Last edited by xatled99; Apr 01, 2012 at 08:23 AM.
Mar 31, 2012, 01:09 PM
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TwoHeadsBrewing's Avatar
Very cool! Are you planning to add a nose cone to it?
Mar 31, 2012, 01:10 PM
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xatled99's Avatar
Yeah, eventually I'll either stick the camera turret up front or make a proper nose cone.
Apr 01, 2012, 03:00 PM
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xatled99's Avatar
scratchbuilt rq7a shadow maiden (2 min 11 sec)
Last edited by xatled99; May 04, 2012 at 05:56 AM.
Apr 02, 2012, 08:44 PM
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xatled99's Avatar
Flew about 5 times yesterday. Power consumption looked good and the plane should get nice long loiter times. Looked to be about a 1:1 thrust:weight ratio; AUW is around 80 (!) oz.

Overall, I'm pretty happy with how it flew. The lack of a proper nose probably didn't do it any favors in the wind. Comes down like a lead balloon at idle, but it didn't exhibit any bad tendencies. Rudder-only turns were a breeze. It didn't seem to like uncoordinated slipping turns.

I hadn't anticipated how much the foam wing would flex spanwise. I suspect it mostly happens on the ground, but I'm tempted to borrow an 808 camera to check it in flight to be sure.
Last edited by xatled99; Apr 03, 2012 at 06:13 PM.
Apr 06, 2012, 09:08 AM
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xatled99's Avatar
In the process of relocating the boom mounts to clean up the incidence angle. This should reduce the amount of up elevator trim required. Might add a thin CF rod to the inboard trailing edge to reduce wing flex. Also added some more plywood sheeting to prevent the trailing edge from bending around the edge of the fuselage.

Replaced the nosewheel steering arm with wheel collars to make the nose installation easier. Started laminating some foam. Undecided whether the nose will be fiberglass or foam or if I'll just use the camera turret after all.

Might pick up a mentor wing and trying using slow stick fuselages as tail booms. Would need to figure out the necessary tail area. I think the extra ~200 sq in would really improve the wing loading. Need to start figuring out ways to save weight.
Apr 06, 2012, 09:34 AM
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I started to build this:

Will update in the future.
Apr 07, 2012, 05:26 PM
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xatled99's Avatar
Next round of mods. Relocating the boom mounts improved the tail incidence. This will also lengthen the tail a little, which should help with stability. Hot glued the dome nose on.

The fuselage alone is about 2.8 lbs. Just the pvc and the motor should be about 1.6, so that leaves about 1.2 for the firewalls and landing gear and wheels. Time to find some fat to trim...
Apr 09, 2012, 06:22 PM
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xatled99's Avatar


I discovered today and realized that I grossly overpaid for that pvc tubing from amazon. 2.5" downspouts and 4" fence post sleeves seem more common and cheap, not to mention coroplast, but I'm not going there.

I also swiss-cheesed the fuselage with a 2.5" holesaw, which saved some weight.

Current totals:
fuselage+firewalls: 20oz
motor: 7oz
landing gear+tires: 10oz (oof!)
wing+tail: 20oz
lipo: 14oz
electronics: 4oz
total AUW: ~ 75oz

Needs some monokote and velcro but otherwise will be ready for remaiden this weekend, weather permitting.
Last edited by xatled99; Apr 12, 2012 at 06:15 PM.
Apr 11, 2012, 05:08 PM
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xatled99's Avatar
For posterity, should I ever build up another one of these, it would look like this:
  • mentor wing
  • Turnigy G10 810kv + APC-E 11x5.5
  • 3s 3000

Use swisscheesed 2.5" pvc downspout for the fuselage. Use slowstick fuselages as tailbooms. Cut channels in the wings and glue the tailbooms directly in for less drag. Should be close to 65oz. Tail sizing as follows.

CG  = 3.300
wing: span=65.000, chord=10.750, area=698.750, AR=6.047
stab: span=22.000, chord=6.000, area=132.000, AR=3.667
fin:                            area=80.000
tail: length=22.000, arm=25.562

V_h = 0.449
V_v = 0.045
NP  = 4.779
SM  = 0.135

equivalent vtail:
area                = 212.000
dimensions          = 35.333 x 6.000
true AR             = 5.889
dihedral angle      = 37.901
projected half span = 13.940
projected AR        = 4.647
projected height    = 10.853
Last edited by xatled99; Apr 11, 2012 at 05:51 PM.
Apr 11, 2012, 07:18 PM
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charlienofun's Avatar
Great work! The specs are much appreciated
Apr 12, 2012, 07:34 AM
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AirRecon's Avatar
Fantastic scratchbuild xatled99, you certainly know your planes!

I'd love to have a platform like this, but wouldnt really know where to start, let alone sourcing all the right components for the build, dimensions, plus fabricating it to completion like this!

Really enjoyed reading through this build, plus the pics and video on Page 3 are the excellent.

Well done. So are you turning this one into a fully featured FPV craft, or more for some AP work?

Very inspiring.
Apr 12, 2012, 06:16 PM
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xatled99's Avatar
Thanks! Yeah, the plan is to equip it for FPV once the kinks have been worked out of the airframe.

Monokoted the fuselage. While I had the gear off, it weighed in at 10 (!) oz; considering making some gear out of 5/32" music wire.
Last edited by xatled99; Apr 12, 2012 at 09:12 PM.

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