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Chris Williams 1/4 Scale T21**

Let us all watch your new project progress.
Sean Fitzgibbon
Posts: 66
Joined: 11 Oct 2017, 18:53
Location: Mitcheldean

Re: Chris Williams 1/4 Scale T21

Post by Sean Fitzgibbon »

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First two of the fuselage longeron doublers added, ensuring a handed pair!
Sean Fitzgibbon
Posts: 66
Joined: 11 Oct 2017, 18:53
Location: Mitcheldean

Re: Chris Williams 1/4 Scale T21

Post by Sean Fitzgibbon »

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Next step has been to dry fit the centre section formers and then think through how to go about the actual assembly.
I'm leaning towards building the rear section over the plan to create a straight, rigid structure before adding in the main formers and then pulling in the longerons to the nose area.
Sean Fitzgibbon
Posts: 66
Joined: 11 Oct 2017, 18:53
Location: Mitcheldean

Re: Chris Williams 1/4 Scale T21

Post by Sean Fitzgibbon »

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More progress this afternoon, all of the cross bracing done, this project is eating spruce and balsa strip!
Sean Fitzgibbon
Posts: 66
Joined: 11 Oct 2017, 18:53
Location: Mitcheldean

Re: Chris Williams 1/4 Scale T21

Post by Sean Fitzgibbon »

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I've found jigging the front end of the fuselage quite tricky, both physically and in terms of finding datums to work to because of the angled formers and large curves.
I've spent a session dry fitting and comparing to the plan and I think I'm happy with how I'm going to proceed.
The rear end is now clamped in the old trusty SLEC jig and the whole thing positioned over the plan to align the main centre formers.
I've glued in the lower keel and worked out it's vertical position at F1 to set it's height.
Once it's set I'll add in F1, F2 and F3 with the top keel to hopefully create a stable front end. Dry fitting did at least prove that slitting the front portion of the longerons eases the pressure required to form the bends significantly. I did find the lower keel is a little short which obviously puts F1 a tad out if position. I plan to compensate by making the nose block a little longer, more room for the inevitable lead! I also remade F4 in 1/4" ply, partly for strength and partly because the fit of the original wasn't great.
Sean Fitzgibbon
Posts: 66
Joined: 11 Oct 2017, 18:53
Location: Mitcheldean

Re: Chris Williams 1/4 Scale T21

Post by Sean Fitzgibbon »

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Took some time to pull in the longerons at the nose, one at a time laminating them together to hold the curve.
Now adding the ply sheeting, I've used epoxy for this more added strength, figuring the weight is forward of the centre of gravity.
When the side panels are in position, I'll cut and fit the strut brackets. Plan is to cut them from hard aluminium, but long enough to be one piece right through the fuselage and epoxied to the former.
User avatar
SedB
Posts: 98
Joined: 14 Nov 2019, 09:17
Location: Netherlands

Re: Chris Williams 1/4 Scale T21**

Post by SedB »

Forming the longerons I found the hardest part so far. I really had issues lining all out and forming them to a proper fit. Looks very promising so far Sean!
Wondering how I can add strength to the front part of the glider, I'm curious how yo'll be making those strut brackets!

Daniel
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