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Old Oct 26, 2014, 05:13 AM
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Ashford. Kent. England
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3DBiplane profile model

In my usual fashion I've been inspired by a number of biplane models, and wanting a model that is 3D capable I've combined a few ideas, shapes and build methods to produce a reasonable model..

The model can be produced with a lighter single layer wing for the smaller sizes or a KF wing when going larger..
or even the small models can be given a KFm2 wing

My first build has been a 23" span single layer wing type, it is definitely going to be more capable than I am once its all sorted ..

NOTE the 23" all now sorted is perfect... and this is the recommended one for indoor flight
Its well 3D capable and I am improving my skills using this design...
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Old Oct 26, 2014, 05:15 AM
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It is going well enough but needs some COG and thrust line adjustment
rates were at mid position..
full deflection is at about 60 degrees each way for all surfaces
.
23inch 3D mini Biplane (7 min 29 sec)
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Old Oct 26, 2014, 05:19 AM
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some more files...pdf plans

the only adjustments required are for the slot thickness... and that depends on your foams

on the 24/26/28 sizes the slots have not been corrected for the thickness of whatever foam you use.. they were simply a scale down from the 30" size

the 22 and 30 have been corrected for use with a 5mm thick EPP foam

NOTE.... servo locations have been altered.. the main wing servo is below the wings the rudder and elevator are fitted flat on the horizontal fuzz, just behind the rear of the top wing... the battery will be below the ailerons of the top wing
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Old Oct 26, 2014, 05:24 AM
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sketchup and dxf files
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Old Oct 26, 2014, 05:40 AM
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here are a few pictures
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Old Oct 26, 2014, 05:44 AM
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The construction methods and some of its looks are based on the crack pitts mini, but there are a lot of alterations to simplify it.. the fuse shape is similar to that of a yak 54 .. a read through the crack pitts threads will give you a good idea of the methods I used to put it together..

I particularly liked the idea of interlocking of wing spars and inter-wing struts, so I further improved on strength by adding more small ply plates at the fuse inter-wing joins
ailerons and control surfaces are all hinged with a tiny bead of UHU por put along the tip of the chamfers used at the hinge line
Horns were made from dental flossers.. Z bends are from paperclips lashed to CF rods..
By heating the Z bend wire holes are made through the flossers, perfect for the Z bends
The pushrod supports are from cable ties, also the U/C legs are cable ties , but now with an added axel and small wheels for better ground take offs
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Old Oct 26, 2014, 06:00 AM
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I am still messing with the setup, the motor now is a 15gm 2300kv turning an 8x3.8 prop.. which will give good vertical..
in the video it was a 2800kv turning a 6" prop, and the throttle response was not so good..
The COG is about on the front of the cut out on the top wing,
AUW heavier than wanted at 135gms + the battery, I am using a 500 2s lipo, but I used quite a lot of hot glue on the build , better to use CA .. keep it as light as possible for the best results...
note my other indoor biplanes are 250gms, so this one is ok, but it could easily be better...

Note Ive further improved the model by going to a hyperion motor.. the z1705-14 with an 8x4.3gws prop the vertical is again much improved...280 gms thrust on a 170gm model..is nice
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Old Oct 26, 2014, 06:03 AM
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Old Oct 26, 2014, 06:05 AM
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Old Oct 26, 2014, 06:46 AM
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Old Oct 26, 2014, 08:12 AM
Slipping the Surly Bonds
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Dave,
Looking really good here. I've been on a bipe kick lately and looks like I am going to give yours a whirl.


Thank you for sharing,
Ken
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Old Oct 26, 2014, 09:45 PM
Slipping the Surly Bonds
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Attica, MI
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Got the basic airframe together. That's always the easy part.

As pictured it is 71g. If she's a good flyer then I'll make one from 3mm Depron or maybe a pocket milled one. Also , I slightly resized the Dxf file to get the tabs close for MPF thickness making it 24.5" wingspan.

Ken
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Old Oct 27, 2014, 02:27 AM
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that was quick...

Is that 6mm depron? 71gms is good for a 24.5 that's lighter than my 23"EPP which was 75gms...
which makes me think a 22 size in the black/dark grey depron would be even lighter.. the grey is a lighter material.
perhaps a KFm2 version in 3mm black would be a good choice, with my micro gear..

My 23" flies well but my build is a bit heavy... I used a couple of glue sticks on mine which was +10gms, then a big 500 lipo, another +16gms extra, Ive added an UC with extra EPP support, and wheels...and a nose block for the motor mount..
it all adds up ..
and my EPP is quite heavy , there are lighter high quality sheets available from else where but they are a lot more expensive.. see robotbirds coloured EPP
so my weight now is 175gms which is about 40- 50gms more than I wanted..

my choices in gear also hasn't helped..
a so called 15gm motor = 20gms for motor and prop, 1x 5gms (nearer 6+gms)main servo , 2x 3.7 (nearer 5gms each)for the others and a 12A esc...

Ive got a couple of other small biplanes with all micro gear from hobbyking... 2gm rx 6A esc, <2gm servos and they are a fair bit lighter and fly well... one is at 125gms, one at 165gms... 125 is a good target but may be difficult when using heavier gear...

but overall this seems to fly just as slow as my others, and it does have far quicker responses, more power etc, so its showing more potential..
I do think that next time I should get very serious about keeping the wing loadings down

since the maiden, Ive changed the motor/prop combo out, for a setup that will spin an 8x3.8 SF prop and go vertical, the motor is another 15gm type, but the slow speed thrust from the big prop feels a lot better.. Ive also added a few degrees of down thrust.. and I added wheels to the cable tie main UC...
For me durability has more importance , our indoor sessions can get a bit damaging.. the lighter more fragile depron models fly well but often get chopped up... its a laugh but it gets frustrating..
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Old Oct 27, 2014, 03:03 AM
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Now I am torn between going up to a 30" for outside or going to a 22" light depron version.....lol.. knowing me it will be both

here are three more files the KF layer parts are now included for KFm2
a pdf for a 22" span for 3mm material with a grid added..slot size adjusted...the dxf for same ...and the sketchup file for same
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