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Would this make a good model?


Martian
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  • 2 weeks later...
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now that the Lancair is finished time to patch up the yellow peril below how it ended up

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Ouch my nose

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cut out for motors (both sides)

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Cardboard tube from cooking foil and brushed motor plastic tube let in for wire route

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tube bonded to wing with epoxy

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motor wrapped in with a little pvc tabe then ca in to tube wires can be seen passing through to underside

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replacement nose in balsa still some work to do and the old bruised nose

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post more in day or two

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some more progress nose cone has been replaced and blended in and have decided to cut to elevators out of the separated tail unit its easier that way when complete will rejoin with splints,

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new nose and general mess

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separated tail section showing bamboo skewers these will be driven in when 2 halves are joined with epoxy I choose the bamboo for a few reasons 1 they were free 2 they are springy and 3 very strong. anyway here you can see the servo cut in to the poly there are now two balsa blocks hardened with ca to screw the servo to also the 2 elevator halves are visible as yet not sanded.the elevator cut outs are lined with 1.5 mm balsa as are the sides of the elevators the front face 4mmx6mm I think

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clearer view of elevator

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here you can see the elevator joiner it is made from softer steel rod than piano wire (its actually the wire support from a paper lamp shade) this is running through a piece of retrieved rc aerial tube as are the end pivot points , thanks to Simon Chaddock for the inspiration

elev cut out.jpg

elevator cut out sanded and painted up.in the middle you can see the white recess where the elevator assembly will slip in complete with the tube then this will be filled with balsa to keep it in place

hinge pin.jpg

Hinge pin at tip ca in place

hinge point at tip.jpg

the securing pin will go through tail tip thru tube the glued in place

joining wire.jpg

all bonded ready for finishing then fitting in to place you can also see servo horn which is made up of to layers of thin ply let into the elevator you can also see the brass ball joint that I am using it is lightweight small and secure (and free from my heli spares box )

more soon

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bit more progress and time to actually pay for some bits ;(

rear fuz repair.jpg

fuselage repair successful bonded with epoxy and reinforced with bamboo skewers ,they flex a little which is good they also grip against the poly very well ,after a little filler will touch up the paint

ae cutout.jpg

aileron cut out ,made a card template so both ae's will be same.the cut out faces in the wing will be faced with 1.5mm balsa but the hinge points will be 1/32 ply and the front face of the ae's will be faced with 6mm balsa and rounded

canopy cut out (1).jpg

canopy cut out this was a bit of a pig to line up but i can make up the discrepancies with balsa (good old balsa) this has weakened the fuz at this point but I still have some bamboo skewers,I had to cutout the canopy area to allow room for the rc gear and batt plus esc the batt will sit further forward towards nose in an area hollowed out to keep CG right,you can just see the outline of a hatch this is to add additional lead if needed.

canopy facing.jpg

canopy faced both sides now will make slight balsa infils to tighten the fit it will be held in place with neo magnets, best get sanding ,more later

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  • 2 weeks later...

Well this is the final stretch,

tail servo ext.jpg

fuselage slotted to take elev servo wire and visible extn

elev wire.jpg

slot for elev servo wire stops jujst short of canopy and a hole is drilled at an angle to exit in lower cockpit area,strips of balsa were pressed in to slot then lightweight filler covering once repainted it will not be seen only the extn connector will be that is covered in masking tape and painted over.

empty cockpit.jpg

servo wires visble elevater and left and right servo wires,same method was used to rout ae wires and power wires.

gear.jpg

gear connected up for control surfaces testing the sharp eyed will spot an orange stabilizer fitted for inital tests on a slope near me if ok will gradually turn down gain.

ae up.jpg

this image shows ae being tested it's about 20mm throw

full span.jpg

she overhangs 6ft table by a fair amount note the puny test motors again subject to a good test I will fit a pair of brushed 480 motors running 8x6 props with a 3s 1800mah .there is quite a bit of flex in the wings they are 80inch so no fancy flying.

hole for ply plate.jpg

this hole is for a softwood insert covered with a ply plate ,the hole exposes the connecting tube it is not very big and came from a helicopter boom,as originally I did not intend to go quite so far with the build.the plate is to accomodate a screw to pass through joining tube and rod to keep it in place 2 to each wing half.

ply horns.jpg

and lastly in keeping with diy bits ply control horns a sandwich of 1/32 plyx2 these are let into the balsa leading edges. A possible mod is to fit balsa leading edges on wing we will se

thanks to Tim Hooper for encouragement and advice yes and encouragement from Tony Bennet and all the clever tricks you guys demonstrate in this forum

now for the maiden when weather permits wish me luck

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  • 3 weeks later...

well the weather was fine low wind and sun so I thought why not, as I predicted the motors are to puny she tip stalled and rolled into the deck breaking a wing of near a motor where there is no support and back broke by the tail all fixable and some valuable lessons. It's clear when I get going with the Balsa model where I need to concentrate more support/strength on these identified weak areas . The all up weight with rc gear 2 motors and 3s 1800 mah lipo came out at 3 pounds and at 80 span I don't think thats to bad . Question is do I continue or do I retrieve all gear and concentrate on the balsa /ply model I can always give my little grandson the rest after mending. I have a feeling that 3lbs is the limit with a poly plane of this size ,the poly has no shear strength and requires to much reinforcing and thereby more weight I could end up going round in circles, what do you think ?

give up or continue

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  • 7 months later...

Well I never did let this go I got hold of a couple of brushed motors (480's ) and knocked up some nacelles not strictly scale like but a nod in the right direction the cable to the motors was totally unsuitable and melted no harm done got some 14swg cable and rewired I have also got a 2s lipo at 1800mah and fitted 8.4 prop ccw and cw and ran it up to full power loads of thrust and draws if I remember close on 400watts. each motor has it's own esc with the batt feed split between them a bit more to do then it will be time to test fly again

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  • 1 month later...

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