MAAC project (catapult/hand chuck)- the Sparrow

[mawz]

well, given my extensive (not) experience with hand-chuck gliders, I volunteered to build the Sparrow, the second of the two kits aimed at the younger set that Athol brought in from MAAC. Frank is of course building the rubber-powered Minnow. Dunno how he's going to fly it with so few watts ;-)

The Sparrow is a 12" span polyhedral hand/catapult launch glider. Included was a catapult for the launching with some lightweight rubber ideal for a small glider like this one.

I'm building entirely with some over-thickened Medium CA, as my experience is that when supervised, this is the best option for kids, as it builds quickly and gets them right into the air. SOGGI ran 2 builds with a JetCo Thermic 18 (upsized to 18" span) with the Air Cadets & at the Tesla Electric Festival, building around 120 Thermic 18's with kids over the course of 2 3-4 hour sessions. The youngest builder was 4 and the oldest around 16. They were quite successful, although the design has a couple weaknesses (largely the 2 stick fuselage tends to break at the leading or trailing edge due to stress risers).

Thermic 18 plans can be found here: https://outerzone.co.uk/plan_details.asp?ID=575

The plans:


the parts:


One of the neat things about this kit is the outer panels have pre-cut angles for the polyhedral joint, but are still attached to the centre section, allowing you to sand the airfoil in one piece and then glue up the dihedral.

The wing after sanding (showing airfoil and the still-attached tip)


The wing and horizontal stab had nice little cut marks to aid alignment on the fuselage.


The pre-cut polyhedral was a neat idea, but in practice the angles were too extreme, leaving large gaps. I'd rather just sand myself and get a better fit. As it is, thickened medium CA sufficed to fill the unsightly gaps.


The horizontal stab installed:


And the vertical stab, which was reversed as I feel this is better for trimming the glider for a mild turn.


By now the first polyhedral joint had dried, so time for the other one.


and finally the wing mounted to the fuselage (which has been rounded off-camera while I waited for glue to dry on the wing)


Just for comparison, here is a Thermic 18 from the kit cut for SOGGI by Marc Freeman.

[bweaver]

@mawz what big thumbs you have!   

Great build.  You are really going to have to beef up the fuselage if you are going put what ever size OS Max motor comes out of that box. 

[mawz]

Thanks Bruce.

That OS motor would be just about right for Franks build, as it's good for about 500W ;-)