Monday, 12 October 2015

Kwik Fli IV (5)

The Final Part...

Back on the cowl.

The engine has been temporarily fitted (and subsequently replaced with a SC61)

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Hardwood blocks added to locate the cowl

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Wrong sized spinner but currently it fits like this

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Managed to chip the glass when trimming down to size but that has subsequently been redone
Its not too bad - weighs 80g.

The next job was to get the wing to fit.
The chord is 1.5" wider at the root than the standard Kwik Fli III wing. The 2 pager out of RCM&E doesn't actually say how to make the change. The root wing section is also somewhat different to the mk III as well so a certain amount of trial and error and sanding etc. to get the wing to fit at the same time at getting the wing level with the tailplane.

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A thick ply wing plate has been fitted - using slow dry epoxy and the wing drilled for 2 M5 Nylon bolts. I then realised I cant measure.. and managed to displace one of the bolts by 5mm 

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I am so cross with myself over that stupid error. Its not too noticeable with the wing fitted though.
This morning, I started fitted out for the radio gear. 3mm Lite ply plates on 10mm sq Pine runners and cross beams.

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After the usual faffing around

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The receiver was replaced with an X8R


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So - this evening, the model assembled on the stand

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And another one, I like it when they are like this...

However, I need to check the wing incidence

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We already established that the tailplane is parallel with the datum. so put the phone on the tailplane and press the zero button

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Put the phone onto the incidence measuring jig platform

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0.4 degrees positive. The plan says for the MkIII it should be +0.5, so that is pretty close. Certainly close enough to risk flying it and then assess. To sanity check, reverse the jig. If the jig is accurate, the incidence should be exactly the same (it was).

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It looks aligned as well. No obvious tail tilt

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And it weighs this much so far. Probably looking at an AUW of 3Kg

The last couple of days have been spent adding detail, sanding down smooth and making a better job of the wing seat. Not much in the way of photos, so yesterday I decided to cover the model and now it looks like this.
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and

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A contrasting (and much simpler) colour scheme underneath

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It's been Tangoed!

This morning I completed the installation of the Radio Gear, everything appear to work in the right direction but it will get final checks before its let loose.

Conventional (if very short) 8G torque legs have been bent up. 8G is about 4mm dia, however, the orifice in the top of the oleo is 5mm so the leg (about 15mm long) was padded out with a length of 0.5mm wall brass tube, hammered into place. The lower set screw location now located in a slot ground into the leg. It seems quite sturdy, time will tell

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And that is the undercarriage done. Its actually not too heavy as the oleo and leg are manufactured from aluminium. Probably a bit more draggy though. If it doesn't work, its very easy to revert to conventional 8G piano wire legs. (Postscript - conventional legs have since been used, I couldn't get these to track consistently)

The cowl has been painted - KlassKote - thanks Andy Green - I painted (sprayed) it and the 'Magic' this morning (the white bits). Its a 2 pack epoxy paint and sets hard in about 6 hours on a warm day.
So now, with the undercarriage done, the cowl fitted and spinner fitted its ready for its maiden. I have a Taranis X8R receiver on order although currently it has a V8 fitted, I have decided to wait for the receiver that I want to use.

CG is a guess as no CG shown on the mods diagram. Currently set about 20mm in front of the main wheels.
The Canopy came from Vortex and sprayed Matt black on the inside after it was cut to fit. A small balsa former cut to the inside front and rear and this was used to glue it to the fuselage. The seam was sealed with Canopy Glue. Looks quite a neat installation.


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and

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and

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It's Ready to Crash.. Aurora 60 next....
3 weeks and 3 days since the first part was cut.. It really is an easy build

Postscript - the model flies well, the cowl seems to have survived but the tailplane needs additional reinforcement. It failed doing a snap roll - folding slightly - causing down elevator and a rather rapid decent. All repairable but the tailplane now has a spruce spar extending about 150mm into each half.